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Home My WebLink AboutCT 14-06; AFTON WAY; AMENDED PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER QUALITY MANAGEMENT PLAN (SWQMP); 2017-07-18- - - .. .. .. .. - 111 - .. -• -----.. -------- r· RECORD COPY Tnitial cr/ry,J Date CITY OF CARLSBAD AMENDED PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) FOR PRECIOUS GRADING PLANS AFTON WAY TM CT 14-06 DWG 495-91, RELATED: DWG 495-9, 495-9A SWOMP NO. 16-2& ENGINEER OF WORK: DATE PREPARED FOR: PRESIDIO PEBBLE CREEK CARLSBAD 8, LLC 301 WEST 28TH STREET, SUITE A NATIONAL CITY, CA 91950 619-938-0312 PREPARED BY: bl-tA, I land planning, surveying 5115 AVENIDA ENCINAS, SUITE L CARLSBAD, CA 92008-4387 (760) 931-8700 DATE: JULY 18, 2017 ·r, t ~" LAND w.o. 1022-1326-600 ""'" -~~ _,,.' .,,. 1'"" ,.... , co,.., ... ' ..,...,. , . bl U''~.-<·:· _;) rt'.. ,., fl<,-'-~ r.::.:·,. ',1 -... .. .. .. .. 411 • .. ... .. .. • - - --- ----- ------ TABLE OF CONTENTS Certification Page Project Vicinity Map FORM E-34 Storm Water Standard Questionnaire Site Information FORM E-36 Standard Project Requirement Checklist Summary of PDP Structural BMPs Attachment 1: Backup for PDP Pollutant Control BMPs Attachment 1 a: DMA Exhibit Attachment 1 b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable) Attachment 1 e: Pollutant Control BMP Design Worksheets/ Calculations Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit Attachment 2b: Management of Critical Coarse Sediment Yield Areas Attachment 2c: Geomorphic Assessment of Receiving Channels Attachment 2d: Flow Control Facility Design Attachment 3: Structural BMP Maintenance Thresholds and Actions Attachment 4: Single Sheet BMP (SSBMP) Exhibit Attachment 5: "Technical Memorandum: SWMM Modeling for Hydromodification Compliance of Afton Way, City of Carlsbad, Revised June 17, 2015", prepared by Tory R. Walker Engineering. "Technical Memorandum: Determination of Pre-and Post-Developed 100-year Peak Flow, Afton Way, City of Carlsbad, June 17, 2015': prepared by Tory R. Walker Engineering. 2 .. .. • .. • .. .. - -... --- -• --.. ---- CERTIFICATION PAGE Project Name: 2200 Afton Way Project ID: CT 14-06 I hereby declare that I am the Engineer in Responsible Charge of design of storm water BMPs for this project, and that I have exercised responsible charge over the design of the project as defined in Section 6703 of the Business and Professions Code, and that the design is consistent with the requirements of the BMP Design Manual, which is based on the requirements of SDRWQCB Order No. R9-2013-0001 (MS4 Permit) or the current Order . I have read and understand that the City Engineer has adopted minimum requirements for managing urban runoff, including storm water, from land development activities, as described in the BMP Design Manual. I certify that this SWQMP has been completed to the best of my ability and accurately reflects the project being proposed and the applicable source control and site design BMPs proposed to minimize the potentially negative impacts of this project's land development activities on water quality. I understand and acknowledge that the plan check review of this SWQMP by the City Engineer is confined to a review and does not relieve me, as the Engineer in Responsible Charge of design of storm water BMPs for this project, of my responsibilities for project design . L R.C.E. 29271 Ex . 03/31/2019 Signature, PE Number & Expiration Date Ronald Holloway Print Name bl-IA, Inc land planning, civii engineering, surveyinfJ July 18, 2017 Date 3 .. - • • • • .. • • .. -... --- - -- --- --- PROJECT VICINITY MAP NO SCALE 4 .. .. • • • • • - - -.. .. - -------.. -- ------ Ccityof Carlsbad STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue {760) 602-2750 www.carlsbadca.gov To address post-development pollutants that may be generated from development projects, the city requires that new development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management Practices (BMPs) into the project design per Carlsbad BMP Design Manual (BMP Manual). To view the BMP Manual, refer to the Engineering Standards (Volume 5). This questionnaire must be completed by the applicant in advance of submitting for a development application (subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of storm water standards that must be applied to a proposed development or redevelopment project. Depending on the outcome, your project will either be subject to 'STANDARD PROJECT' requirements or be subject to 'PRIORITY DEVELOPMENT PROJECT' (PDP) requirements. Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City staff has responsibility for making the final assessment after submission of the development application. If staff determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than initially assessed by you, this will result in the return of the development application as incomplete. In this case, please make the changes to the questionnaire and resubmit to the city. If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the questions, please seek assistance from Land Development Engineering staff. A completed and signed questionnaire must be submitted with each development project application. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. PROJECT NAME: Afton Way PROJECT ID:CT 14-06, HDP 14-05, HMP 15-03 ADDRESS: 2200 Afton Way, Carlsbad, CA 92008 APN: 167-531-45, 167-250-06 The project is (check one):~ New Development D Redevelopment The total proposed disturbed area is: 146,606 ft2 ( 3.37 ) acres The total proposed newly created and/or replaced impervious area is: 62,947 tt2 ( 1.45 ) acres If your project is covered by an approved SWQMP as part of a larger development project, provide the project ID and the SWQMP # of the larger development project: Project ID _________________ SWQMP #: _________________ _ Then, go to Step 1 and follow the instructions. When completed, sign the form at the end and submit this with your application to the city. E-34 Page 1 of 4 REV 02/16 .. • - • - • .. .. • • -- .. ------.. ---.. - -- To determine if your project is a "development project", please answer the following question: Is your project LIMITED TO routine maintenance activity and/or repair/improvements to an existing building or structure that do not alter the size {See Section 1.3 of the BMP Design Manual for guidance)? YES NO □ 00 If you answered "yes" to the above question, provide justification below then go to Step 5, mark the third box stating "my project is not a 'development project' and not subject to the requirements of the BMP manual'' and complete applicant information. Justification/discussion: {e.g. the project includes only interior remodels within an existing building): To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.{3), please answer the following questions: Is your project LIMITED to one or more of the following: 1. Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria: a) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non- erodible permeable areas; b) Designed and constructed to be hydraulically disconnected from paved streets or roads; c) Designed and constructed with permeable pavements or surfaces in accordance with USEPA Green Streets uidance? 2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in accordance with the USEPA Green Streets guidance? 3. Ground Mounted Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual? YES NO □ 00 □ □ If you answered "yes" to one or more of the above questions, provide discussion/justification below, then go to Step 5, mark the second box stating "my project is EXEMPT from PDP ... " and complete applicant information. Discussion to justify exemption { e.g. the project redeveloping existing road designed and constructed in accordance with the USEPA Green Street guidance): E-34 Page2 of 4 REV 02/16 .. .. .. .. .. .. .. .. --------- ---- ---- To determine if your project is a PDP, please answer the following questions (MS4 Permit Provision E.3.b.(1 )): 1. Is your project a new development that creates 10,000 square feet or more of impervious surfaces collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, and ublic develo ment ro ·ects on ublic or rivate land. 2. Is your project a redevelopment project creating and/or replacing 5,000 square feet or more of impervious surface collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surface? This includes commercial, industrial, residential, mixed-use, and public develo ment ro ·ects on ublic or rivate land. 3. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial Classification SIC code 5812 . 4. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a hillside development project? A hillside develo ment ro·ect includes develo ment on an natural slo e that is twent -five ercent or reater . 5. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more of impervious surface collectively over the entire project site and supports a parking lot? A parking lot is a land area or facility for the temporary parking or storage of motor vehicles used personally for business or for commerce . 6. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more of impervious surface collectively over the entire project site and supports a street, road, highway freeway or driveway? A street, road, highway, freeway or driveway is any paved impervious surface used for the trans ortation of automobiles, trucks, motorc cles, and other vehicles. 7. Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more of impervious surface collectively over the entire site, and discharges directly to an Environmentally Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of 200 feet or less from the project to the ESA, or conveyed in a pipe or open channel any distance as an isolated flow from the ro ·ect to the ESA i.e. not commin led with flows from ac:facent lands . * 8. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square feet or more of impervious surface that supports an automotive repair shop? An automotive repair shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC) codes: 5013, 5014, 5541, 7532-7534, or 7536-7539. 9. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square feet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily Traffic 'AD of 100 or more vehicles er da . 10. Is your project a new or redevelopment project that results in the disturbance of one or more acres of land and are expected to generate pollutants post construction? 11. Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of impervious surface or (2) increases impervious surface on the property by more than 10%? (CMC 21.203.040 YES NO □ □ Iii □ □ □ Iii □ 1K] □ □ □ Iii □ □ If you answered "yes" to one or more of the above questions, your project is a PDP. If your project is a redevelopment project, go to step 4. If your project is a new project, go to step 5, check the first box stating "My project is a PDP ... " and complete applicant information. If you answered "no" to all of the above questions, your project is a 'STANDARD PROJECT.' Go to step 5, check the second box statin "M ro·ect is a 'STANDARD PROJECT' ... " and com lete a licant information. E-34 Page 3 of 4 REV 02/16 • .. • 41 .. • • • - ---.. 11111 ----... -.. -• -.. Complete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)): Does the redevelopment project result in the creation or replacement of impervious surface in an amount of less than 50% of the surface area of the previously existing development? Complete the percent impervious calculation below: Existing impervious area (A)= ___________ sq. ft. Total proposed newly created or replaced impervious area (B) = ___________ s.q. ft. Percent impervious area created or replaced (B/A)*100 = _____ % YES NO □ □ If you answered •yes", the structural BMPs required for PDP apply only to the creation or replacement of impervious surface and not the entire development. Go to step 5, check the first box stating "My project is a PDP ... • and complete applicant information. If you answered "no," the structural BMP's required for PDP apply to the entire development. Go to step 5, check the check the first box statin "M to' ect is a PDP ... • and com lete a Ii cant information. 00 My project is a PDP and must comply with PDP stormwater requirements of the BMP Manual. I understand I must prepare a Storm Water Quality Management Plan (SWQMP) for submittal at time of application. 0 My project is a 'STANDARD PROJECT' OR EXEMPT from PDP and must only comply with 'STANDARD PROJECT' stormwater requirements of the BMP Manual. As part of these requirements, I will submit a • Standard Project Requirement Checklist Form E-36" and incorporate low impact development strategies throughout my project. Note: For projects that are close to meeting the PDP threshold, staff may require detailed impervious area calculations and exhibits to verify if 'STANDARD PROJECT' stormwater requirements apply . D My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual. Applicant Information and Signature Box Applicant Name: Gary Arnold Applicant Title: _O~p_e_ra_ti_n=g_M_a_n_a_g~e_r ______ _ Applicant Signature: ~ °j_ L:J[} Date: -:f u'4C. z6'"' -z:.o, b • Environmentally Sensitive Areas lncllJde but are not limited to all Clean Water Act Section 303(d) impairecf water bodies; areas designated as Areas or Special Biological Significance by the State Water Resources Control Beard (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodies designated with the RARE beneficial use by the State water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994} and amendments); areas designated as preserves or their equivalent under the Multi Species conservation Program Within the Cities and County of San Diego; Habitat Management Plan: and any ether equivalent environmentally sensitive areas which have been identified by the City. This Box for Ci Use On/ YES NO City Concurrence: □ By: (), \ l 1-( Date: 'f p .... I -, Project ID: c:-r I -06 Page4 of 4 REV02/16 - .. • .. • .. • • -------.. -- • • • .. -- -.. SITE INFORMATION CHECKLIST Project Name Project ID Project Address Assessor's Parcel Number(s) (APN(s)) Project Watershed (Hydrologic Unit) Project Hydrologic Unit Hydrologic Area Parcel Area (total area of Assessor's Parcel(s) associated with the project) Area to be disturbed by the project (Project Area) Project Proposed Impervious Area (subset of Project Area) Project Proposed Pervious Area 2200 Afton Way CT 14-06 2200 Afton Way, Carlsbad, CA 167-531-45 and 167-250-06 IZI Carlsbad 904 Select One: D Loma Alta 904.1 IZI Buena Vista Creek 904.2 D Agua Hedionda 904.3 D Encinas 904.4 D San Marcos 904.5 D Escondido Creek 904.6 4.94 Acres ( 214,993 Square Feet) 3.37 Acres ( 146,655 Square Feet) 1.45 Acres ( 62,947 Square Feet) (subset of Project Area) 1.92 Acres 83,708 Square Feet) Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the Project. This may be less than the Parcel Area . 6 • • • .. • .. • ... • .. • -------------.. -.. ---- Current Status of the Site (select all that apply): C8] Existing development D Previously graded but not built out D Agricultural or other non-impervious use C8] Vacant, undeveloped/natural Description / Additional Information: The project site is divided by east and westbound Carlsbad Village Drive. The subject property located south of Carlsbad Village Drive, known as Parcel 1 for reference, is approximately 4.57 acres and currently contains a single family residential home, driveway, and detached garage. The remaining site is vacant and bordered by Carlsbad Village Drive to the north, and existing residential developments to the east, south, and west. Existing land-use is 1.00 DU/Ac . The subject property located north of Carlsbad Village Drive, Parcel 2, is approximately 0.37 acres and is bordered by Carlsbad Village Drive to the south, Rising Glen Way to the east, and a multi-story apartment complex to the north. Existing land-use is undisturbed natural terrain and proposes to remain undisturbed . Existing Land Cover Includes (select all that apply): D Vegetative Cover C8] Non-Vegetated Pervious Areas C8] Impervious Areas Description/ Additional Information: Parcel 1 includes an existing residential house, driveway, and detached garage in the northwestern portion of the site. The remaining site is undisturbed natural terrain with few scattered shrubs. Parcel 2 is an undeveloped hillside with few scattered shrubs. Underlying Soil belongs to Hydrologic Soil Group (select all that apply): 0 NRCSTypeA C8] NRCS Type B 0 NRCSTypeC C8] NRCS Type D 7 .. .. .. .. Approximate Depth to Groundwater (GW): • 0 GW Depth < 5 feet • D 5 feet < GW Depth < 1 0 feet • D 1 0 feet < GW Depth < 20 feet • ~ GW Depth > 20 feet • • • .. .. .. .. .. • .. • ------.. -• • • -----8 --- , _,..._ __ ,,,,. .... _. ~-"~~ -• .. • .. • • • .. .. • .. --.. --------• --- - -- Existing Natural Hydrologic Features (select all that apply}: D Watercourses D Seeps D Springs D Wetlands ~ None Description/ Additional Information: There are no existing natural hydrologic features . 9 • • • • • • • • --.. ----- .. -.. ---- Description of Existing Site Topography and Drainage [How is storm water runoff conveyed from the site? At a minimum, this description should answer (1} whether existing drainage conveyance is natural or urban; (2) describe existing constructed storm water conveyance systems, if applicable; and (3) is runoff from offsite conveyed through the site? if so, describe]: Parcel 1 is bordered by Carlsbad Village Drive to the north, and existing residential developments to the east, south, and west. Topographically, the property consists of gently sloping hillside terrain with elevations ranging from a high of approximately 280 feet Mean Sea Level (MSL} near the southwestern property line to a low of approximately 205 feet MSL at the property's northeastern comer. Currently, the property is occupied by one residential structure with two sheds. An existing crib wall, approximately 26 feet high and 300 feet long, is located along the north boundary of the site. Site drainage is presently accomplished through a generally northeasterly trending ravine and sheet flows southeasterly to drainage facilities along Carlsbad Village Drive. Existing brow ditches at the top of cut slopes along the southeastern project boundary direct runoff to existing catch basins, which ultimately discharge into the storm drain system underneath Carlsbad Village Drive. Existing brow ditches at the top of cut slopes along the crib wall direct runoff to sidewalk underdrain pipes at various locations along Carlsbad Village Drive and eventually enter the storm drain system underneath Carlsbad Village Drive via Type-B Curb Inlet at the east comer of the project boundary. Vegetation consists of native grasses and eucalyptus trees over the majority of the site. The on-site soil classification is Type-B and Type- D from USDA Web Soil Survey (see References}. Parcel 2 is bordered by Carlsbad Village Drive to the south, Rising Glen Way to the east, and a multi-story apartment complex to the north. Topographically, the property is a hillside dominated by an east to west trending ridge that rises approximately 50 feet above the lowest site terrain along the northwestern property line. Site terrain continues to support bare ground and scattered shrubs. The on-site soil classification is Type-D from USDA Web Soil Survey (see References}. The existing drainage area is divided into six basins and one POC, located east of the project site near Carlsbad Village Drive. The Existing Condition Hydrology Map shows the four drainage Basins labeled A through D for Parcel 1 and drainage Basins E and F for Parcel 2. Basin A sheet flows from the southwest side of the existing residence, across the existing driveway and into an existing brow ditch at the top of the cut slope along the southeasterly project boundary line. An existing catch basin at the east comer of the project boundary intercepts this runoff and connects to the existing storm drain system underneath Carlsbad Village Drive. Basin B sheet flows from the top of the southwesterly ravine and towards the easterly boundary of the subject property and into an existing brow ditch. The brow ditch conveys flow into an existing catch basin where it enters the storm drain system underneath Afton Way. This storm drain system connects with the existing storm drain system underneath Celinda Drive and eventually Carlsbad Village Drive. Basin C is limited to the storm flows that land on the existing driveway, with some flow-on from the ravine located between the neighboring properties and upstream of the driveway. Runoff is 10 .. • - • • • • • • • • • • - -- • -------- -.. -- carried through the existing curb and gutter along the driveway and discharges onto Afton Way and toward curb inlets on Celinda Drive . Basin D is north of Basin A and sheet flows from the top of the ridge west of the existing on-site property and towards Carlsbad Village Drive through a series of brow ditches and sidewalk underdrain pipes. Basin D also includes run-on coming from the highest point of Carlsbad Village Drive to the existing Type-B Curb Inlet at the southwest corner of the intersection of Celinda Drive and Carlsbad Village Drive. Basin E is in the northwest portion of Parcel 2. Runoff sheet flows from the top of the ridge and onto Carlsbad Village Drive, then discharges into an existing Type-B Curb Inlet at the northwest corner of Celinda Drive and Carlsbad Village Drive. Basin E also includes run-on coming from the highest point of Carlsbad Village Drive to the existing curb inlet. Basin F is located in Parcel 2 and sheet flows east from the top of the hill towards the existing parking lot in the back of the existing multi-story apartment complex. This area that acts in a sheet flow condition comprises of approximately 0.23 acres. Sheet flow analysis is not necessary for this area as the proposed project does not propose any new impervious area added to Basin F. In addition, no impervious contributing area is added to Basin E and therefore does not include a post-development hydrologic analysis . 11 .. .. • .. 111 • • .. .. • --.. --.. ---- .. ---.. -... Project Description / Proposed Land Use and/or Activities: The Afton Way Project proposes the development of 8 residential lots and grading of pads and driveways, and a new public cul-de-sac on Afton Way. The project also proposes drainage facility improvements consisting of minor concrete drainage channels, storm drain pipes, curb inlets, and two detention-biofiltration basins for storm water treatment and hydromodification. Storm water runoff from the project site is routed to one POC, located east of the project site near Carlsbad Village Drive. Runoff is drained to tow independent onsite receiving biofiltration LID IMPs called Basin 1 and Basin 2. The disturbed area is approximately 3.37 acres of the 4.94 acre site. Proposed land-use is 2.88 DU/Ac . List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features): The proposed impervious features of the project include the 8 proposed single-family residences and driveways and the new cul-de-sac on Afton Way . List/describe proposed pervious features of the project (e.g., landscape areas): The proposed pervious features of the project include landscape areas surrounding the proposed residences and the (2) proposed biofiltration basins on Lot 9 . Does the project include grading and changes to site topography? [8J Yes □ No Description/ Additional Information: Project grading will occur on approximately 3.37 acres of the project. Grading on the site has been minimized to the maximum extent possible. The existing residential house and sheds located on site will be removed as part of the project. The project as proposed will endeavor to maintain the existing cross lot drainage condition for both overall rate and flow conditions. See the DMA Exhibit for post-development drainage patterns. Impervious surfaces have been minimized where feasible. 12 .. • • • ,. • • ... • • -.. --- • ... -----.... --- -- Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)? [g!Yes □ No Description / Additional Information: The proposed drainage pattern will be similar to the existing drainage pattern with some modifications to incorporate the Best Management Practices (BMPs) into the project design to mimic the impacts on storm water runoff and quality. The proposed runoff from the project site is divided into five (5) Drainage Management Areas (DMAs): (1) OMA Draining to a Biofiltration IMP and (4) Self-Mitigating DMAs. One Point of Compliance (POC-1) has been identified at Node 105, which is the point at which the majority of the proposed site runoff will be discharge to the Carlsbad MS4 system (see Attachment 1 for Drainage Management Area (OMA) Exhibit). Only Basins A through D are being developed and will consider urban runoff flow rates, durations and velocities. The developed Basin A, or OMA 1, will encompass runoff from Lots 1-6, which will be directed to the front of each lot and onto the proposed cul-de-sac. Runoff will then travel via curb and gutter to a proposed Type-B Curb Inlet on the south side of Afton Way. Runoff from Lots 7 and 8 will be directed to the front of each lot and onto the proposed cul-de-sac, then travel via curb and gutter to a proposed Type-B Curb Inlet on the north side of Afton Way. The proposed curb inlets will connect to a proposed 18"-dia PVC storm drain pipe adjacent to the eastern project boundary. The 18"-dia storm drain pipe will discharge into a modified Type A-7 Clean Out (per SDRSD D-09). The cleanout will include (2) orifices to distribute flow. The size of the orifices are a function of the size of each basin divided by the area of the two basins combined. Once flows are routed via the proposed orifices, the flows are then conveyed via storm drain pipes to the receiving biofiltration LID I MPs called Basin 1 and Basin 2 for treatment and detention. Outflows from the basins will be conveyed via 12" -dia storm drain pipe to the existing Type-B Curb Inlet at POC-1. The majority of the off-site run-on from Basin B will be intercepted by a proposed brow ditch along the southern and eastern project boundary line and directed to a proposed catch basin on the south side of Afton Way. The catch basin will connect to a proposed 18"-dia storm drain system which will connect to the existing 18" -dia storm drain system underneath Afton Way and eventually Carlsbad Village Drive. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating OMA, SM 1, per Chapter 5 Section 5.2.1 of the City of Carlsbad BMP Design Manual (BMP OM). The off-site run-on from Basin C will be intercepted by a proposed brow ditch along the western project boundary line and directed to a proposed catch basin near the congruent property line of Lot 4 and Lot 5. The catch basin will outlet to a proposed 18"-dia PVC storm drain system which will travel under the proposed cul-de-sac and connect to the existing 18"-dia storm drain system underneath Afton Way and eventually Carlsbad Village Drive. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating OMA, SM 2, per the BMP OM. 13 .. -• .. .. -• - • • • • --.. --- ------- .. ---- The remaining runoff in Basin D is proposed to be intercepted by the existing brow ditches at the top of cut slopes along the crib wall and directed to the existing sidewalk underdrain pipes at various locations along Carlsbad Village Drive. The runoff will then enter the existing storm drain system underneath Carlsbad Village Drive as historically. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating DMA, SM- 3, per the BMP DM . The proposed drainage facility improvements will consist of minor concrete drainage channels, storm drain pipes, curb inlets, and two detention-biofiltration basins. The biofiltration basins proposed for the four main Drainage Basins A - D are designed so that increases in the drainage discharge rate and velocity will be mitigated up to the 100-year runoff. The proposed biofiltration basins will serve to detain the very minor calculated increase in runoff created by the proposed development, and to mitigate any concentration of storm water discharge that might cause erosion . 14 - • • • • • .. .. • .. ----.. ---.. - --- -- Identify whether any of the following features, activities, and/or pollutant source areas will be present (select all that apply): ~ On-site storm drain inlets D Interior floor drains and elevator shaft sump pumps D Interior parking garages ~ Need for future indoor & structural pest control ~ Landscape/Outdoor Pesticide Use D Pools, spas, ponds, decorative fountains, and other water features D Food service D Refuse areas D Industrial processes D Outdoor storage of equipment or materials D Vehicle and Equipment Cleaning D Vehicle/Equipment Repair and Maintenance D Fuel Dispensing Areas D Loading Docks D Fire Sprinkler Test Water D Miscellaneous Drain or Wash Water D Plazas, sidewalks, and parking lots 15 .. - - • • .. .. .. .. .. .. -- -.. -- .. • -• .. -- Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable): From the project site, runoff flows into a storm water conveyance system that discharges into Buena Vista Creek, which eventually discharges into Buena Vista Lagoon and the Pacific Ocean. List any 303(d) impaired water bodies within the path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the pollutant(s)/stressor(s) causing impairment, and identify any TMDLs for the impaired water bodies: 303(d) Impaired Water Body Pollutant( s )/Stress or( s) TMDLs Sediment Toxicity Buena Vista Creek 904.2 Selenium Indicator bacteria Buena Vista Lagoon 904.2 Nutrients Sedimentation/siltation Identify pollutants expected from the project site based on all proposed use(s) of the site (see BMP Design Manual Appendix B.6): Not Applicable to the Expected from the Also a Receiving Project Site Project Site Water Pollutant of Pollutant Concern Sediment □ ~ ~ Nutrients □ ~ ~ Heavy Metals □ ~ ~ Organic Compounds □ ~ ~ Trash & Debris □ ~ ~ Oxygen Demanding Substances □ ~ ~ Oil & Grease □ ~ ~ Bacteria & Viruses □ ~ ~ Pesticides □ ~ ~ 16 .. -• • .. • • • .. .. 41 .. • • .. - --... .. -.. • -• .. .. -- Do hydromodification management requirements apply (see Section 1.6 of the BMP Design Manual)? IZI Yes, hydromodification management flow control structural BMPs required . D No, the project will discharge runoff directly to existing underground storm drains discharging directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean. D No, the project will discharge runoff directly to conveyance channels whose bed and bank are concrete-lined all the way from the point of discharge to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean. D No, the project will discharge runoff directly to an area identified as appropriate for an exemption by the WMAA for the watershed in which the project resides. Description / Additional Information (to be provided if a 'No' answer has been selected above): Project is subject to hydromodificaiton management requirements. Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas exist within the project drainage boundaries? □Yes IZI No, No critical coarse sediment yield areas to be protected based on WMAA maps If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual been performed? D 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite D 6.2.2 Downstream Systems Sensitivity to Coarse Sediment D 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite D No optional analyses performed, the project will avoid critical coarse sediment yield areas identified based on WMAA maps If optional analyses were performed, what is the final result? D No critical coarse sediment yield areas to be protected based on verification of GLUs onsite D Critical coarse sediment yield areas exist but additional analysis has determined that protection is not required. Documentation attached in Attachment 8 of the SWQMP. D Critical coarse sediment yield areas exist and require protection. The project will implement management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas are identified on the SWQMP Exhibit. Discussion / Additional Information: Critical coarse sediment yield areas do not exist on site or upstream of the project. 17 • • • • • • .. • .. .. .. • - ---- -- .. .. • -.. List and describe point(s} of compliance (POCs} for flow control for hydromodification management (see Section 6.3.1 }. For each POC, provide a POC identification name or number correlating to the project's HMP Exhibit and a receiving channel identification name or number correlating to the project's HMP Exhibit. One Point of Compliance (POC-1} has been identified at the existing Type B curb inlet on the south side of Carlsbad Village Drive, which is the point at which the majority of the proposed site runoff will be discharge to the Carlsbad MS4 system (see Attachment 1 for Drainage Management Area (DMA} Exhibit}. A SWMM analysis has been prepared that describes the pre and post-development hydrologic analysis and ensures that post-development peak flow is less than or equal to pre-development peak flow for the 6-hour 100-yn ear storm event at the project's point of compliance (POC-1 }. See the HMP Exhibit and Attachment 2 for hydromodification control details. See Attachment 5 for copy of SWMM reports . Has a geomorphic assessment been performed for the receiving channel(s}? ~ No, the low flow threshold is 0.1O2 (default low flow threshold} D Yes, the result is the low flow threshold is 0.1O2 D Yes, the result is the low flow threshold is 0.3Q2 D Yes, the result is the low flow threshold is 0.5Q2 If a geomorphic assessment has been performed, provide title, date, and preparer: Discussion / Additional Information: (optional} 18 • • • • • • .. • • • • .. .. • • - -- .. ---.. -.. ----- When applicable, list other site requirements or constraints that will influence storm water management design, such as zoning requirements including setbacks and open space, or local codes governing minimum street width, sidewalk construction, allowable pavement types, and drainage requirements . The project proposes single family residential dwellings constructed on lots that range from 12,200 sf to 19,200 sf. The space available to install suitable private biofiltration basins is very limited . The Type-D soil existing on-site provides little opportunity for infiltration of storm water runoff into native soils. Storm water strategies that utilize infiltration are not suitable; therefore biofiltration basins will be lined with an impermeable liner to prevent infiltration of storm water. The site currently has a northerly-facing slope descending from the project site to Carlsbad Village Drive. An open space between the grading of pads and the northerly boundary line will remain untouched to protect the steep slope from failure and erosion. Special precautions must be taken while grading the pads so that the open space does not channel the flow in any way, but instead the pads display an even grade and distribute the runoff evenly to the proposed cul- de-sac . 19 • • • -.. - • .. • .. • .. • • • ---.. .. .. • -.. -- Cicy of Carlsbad Project Name: Afton Way STANDARD PROJECT REQUIREMENT CHECKLIST E-36 Project ID:CT 14-06, HDP 14-05, HMP 15-03 DWG No. or Building Permit No.: Development Services Land Development Engineering 1635 Faraday Avenue {760) 602-2750 www.carlsbadca.gov All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. See Chapter 4 and Appendix E.1 of the BMP Design Manual for information to implement source control BMPs shown in this checklist. Answer each category below pursuant to the following . • "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1 of the Model BMP Design Manual. Discussion/justification is not required . • "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion/justification must be provided. Please add attachments if more space is needed . • "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion/justification may be rovided. SC-1 Prevention of Illicit Discharges into the MS4 Discussion/justification if SC-1 not implemented: Irrigation water and vehicle and wash water will be directed away from impervious surfaces . SC-2 Storm Drain Stenciling or Signage i2J Yes □ No □ N/A Discussion/justification if SC-2 not implemented: Storm drains will be stenciled or stamped with anti-dumping message. See DMA Exhibit for location of storm drain inlets . SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Discussion/justification if SC-3 not implemented: No outdoor materials storage areas proposed . E-36 Page 1 of 4 □Yes □ No i21 N/A Revised 03/16 ---• -• • -• ---- -----.. - - ---- ', ' ~ ... • .-·=:::,-- SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and Wind Dis ersal Discussion/justification if SC-4 not implemented: No materials will be stored in outdoor work areas. SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal □Yes □ No ill N/A Discussion/justification if SC-5 not implemented: No trash areas proposed. SC-6 Additional BMPs based on Potential Sources of Runoff Pollutants must answer for each source listed below and identif additional BMPs. See Table in A endix E.1 of BMP Manual for uidance . ill On-site storm drain inlets □Yes □No □ N/A □ Interior floor drains and elevator shaft sump pumps □Yes □No ill N/A □ Interior parking garages □Yes □No ill N/A □ Need for future indoor & structural pest control i2J Yes □No □ N/A □ Landscape/Outdoor Pesticide Use i2J Yes □No □ N/A □ Pools, spas, ponds, decorative fountains, and other water features □Yes □No ill N/A □ Food service □Yes □No ill N/A □ Refuse areas □Yes □No ill N/A □ Industrial processes □Yes □No ill N/A □ Outdoor storage of equipment or materials □Yes □No ill N/A □ Vehicle and Equipment Cleaning □Yes □No ill N/A □ Vehicle/Equipment Repair and Maintenance □Yes □No ill N/A □ Fuel Dispensing Areas □Yes □No ill N/A □ Loading Docks □Yes □No ill N/A □ Fire Sprinkler Test Water □Yes □No ill N/A □ Miscellaneous Drain or Wash Water □Yes □No ill N/A For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No" answers. An Operation and Maintenance (O&M) Plan will be provided to future occupants that will acknowledge the potential pollutant sources and provide educational materials to prevent illicit discharges to the storm drain system. The following will discuss how source control requirements will be applied to the project: • Storm drain inlets and catch basins will be labeled with "No Dumping Drains to Waterways". See DMA Exhibit for structural BMP label. • Pest-resistant or well-adapted plant varieties such as drought tolerant and/or native plants will be planted in landscape areas. Integrated Pest Management (1PM) educational materials will be distributed to future occupants as a component of the O&M Plan that address physical pest elimination techniques such as relying on natural enemies to consume pests, weeding, pruning, and etc. E-36 Page 2 of 4 Revised 03/16 .. .. .. • • .. --.. - • ---- --- - -- All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual for information to implement site design BMPs shown in this checklist. Answer each category below pursuant to the following. • "Yes" means the project will implement the site design BMPs as described in Chapter 4 and/or Appendix E.2 thru E.6 of the Model BMP Design Manual. Discussion / justification is not required. • "No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must be provided. Please add attachments if more space is needed. • "N/A" means the BMPs is not applicable at the project site because the project does not include the feature that is addressed by the BMPs (e.g., the project site has no existing natural areas to conserve). Discussion/justification may be rovided. Discussion/justification if SD-1 not implemented: The overall drainage patterns of the site will be maintained SD-2 Conserve Natural Areas, Soils, and Vegetation i2I Yes □ No □ N/A Discussion/justification if SD-2 not implemented: Natural areas will exist on the project site due to minimized grading . SD-3 Minimize Im ervious Area i2I Yes □ No □ N/A Discussion/justification if SD-3 not implemented: Landscape buffers will be incorporated between sidewalks and Afton Way . SD-4 Minimize Soil Com action i2I Yes □ No □ N/A Discussion/justification if SD-4 not implemented: Soil compaction will be minimized in natural landscape areas. Disturbed slope soils will also be amended and aerated. SD-5 Impervious Area Dispersion i2I Yes □ No □ N/A Discussion/justification if SD-5 not implemented: Landscape will effectively receive and infiltrate, and treat runoff from impervious areas as much as possible. Roof drains will be directed to landscape areas prior to discharging to storm water conveyance. E-36 Page 3 of 4 Revised 03/16 - - • • • .. .. • • ---.. ----.. -.. .. ---.. - Discussion/justification if SD-6 not implemented: Although landscape areas will effectively receive and infiltrate runoff as much as possible into native soils, the landscape areas are not designed to retain runoff in a way that can be credited towards reducing the overall DCV . SD-7 Landsca in with Native or Drou ht Tolerant S ecies i2I Yes □ No □ N/A Discussion/justification if SD-7 not implemented: Slope soils will be amended, aerated, and planted with native or drought tolerant non-native plants. Other landscape or pervious areas will incorporate native or drought tolerant landscape design. □Yes iZ1 No □ N/A Discussion/justification if SD-8 not implemented: No rain-water harvesting strategies proposed. Harvest and use is considered to be infeasible for this project. See Form 6 in Attachment 1 c for Harvest and Use Feasibility Checklist. E-36 Page4 of 4 Revised 03/16 • • • .. ... • .. .. .. • • - --- - -• • • • --- SUMMARY OF PDP STRUCTURAL BMPS All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of the BMP Design Manual). Selection of PDP structural BMPs for storm water pollutant control must be based on the selection process described in Chapter 5. PDPs subject to hydromodification management requirements must also implement structural BMPs for flow control for hydromodification management (see Chapter 6 of the BMP Design Manual). Both storm water pollutant control and flow control for hydromodification management can be achieved within the same structural BMP(s) . PDP structural BMPs must be verified by the local jurisdiction at the completion of construction. This may include requiring the project owner or project owner's representative to certify construction of the structural BMPs (see Section 1.12 of the BMP Design Manual). PDP structural BMPs must be maintained into perpetuity, and the local jurisdiction must confirm the maintenance (see Section 7 of the BMP Design Manual) . Use this form to provide narrative description of the general strategy for structural BMP implementation at the project site in the box below. Then complete the PDP structural BMP summary information sheet (page 3 of this form) for each structural BMP within the project (copy the BMP summary information page as many times as needed to provide summary information for each individual structural BMP). Describe the general strategy for structural BMP implementation at the site. This information must describe how the steps for selecting and designing storm water pollutant control BMPs presented in Section 5.1 of the BMP Design Manual were followed, and the results (type of BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether pollutant control and flow control BMPs are integrated or separate. For the purpose of this SWOMP, the proposed site condition has been divided into (5) Drainage Management Areas (DMAs): (1) OMA Draining to a Biofiltration IMP and (4) Self-Mitigating DMAs. The DMAs have been delineated based on onsite drainage patters and BMP locations. Biofiltration basins (BF-1) were chosen as the structural BMP for DMAs draining to IMPs. Two biofiltration basins, Basin 1 and Basin 2, will be used for pollutant control and peak flow control for the project stormwater runoff. The outlet structure for Basin 1 and Basin 2 have been designed based on results from the Technical Memorandum: SWMM Modeling for Hydromodification Compliance for Afton Way, dated April 9, 2015 from Tory R. Walker Engineering under separate cover (see Attachments section of this Report for copy of Technical Memorandum). This SWMM Model demonstrates Hydromodification Compliance at the proposed basins for the 02 to 010 return periods as specified in the County of San Diego Hydromodification Plan (HMP). Based on the hydrologic model used in the technical memorandum titled above, a separate SWMM analysis has been prepared that describes the pre and post-development hydrologic analysis ensures that post- development peak flow is less than or equal to pre-development peak flow for the 6-hour 100- year storm event at the project's point of compliance (POC-1 ). See References for copy of Title Page, Technical Memorandum: Determination of Pre-and Post-Developed 100-year Peak Flow 21 • • • • .. • .. • • • ----.. - - • .. • ... -- from Tory R. Walker Engineering dated June 17, 2015. The Rational Method study provided in the associated Drainage Report for this project incorporates the outlet structure design in the Technical Memorandum, and is meant to enhance the study from Tory R. Walker Engineering, Inc. to show the site can sufficiently convey the 100 year storm event. The two I MPs are responsible for handling hydromodification requirements for the project site. In developed conditions, both Basins 1 and 2 will have a surface depth of 3 feet and 2.5 feet, and a riser spillway structure (see dimensions in the DMNIMP Sizing Exhibit in Attachments). Flows will discharge from the biofiltration cells via a low flow orifice outlet within the gravel layer or a surface slot with the riser structure. The top of the riser structure will act as a spillway, such that peak flows can be safely discharged to the receiving storm drain system . Beneath the invert of the basins' lowest surface discharge lies the proposed LID biofiltration portion of the drainage facility. This portion of the basins is comprised of 12 inches of surface storage, an 18-inch layer of amended soil (a highly sandy, organic rich composite with an infiltration capacity of at least 5 inches/hr.) and a 12-inch layer of gravel for additional detention and to accommodate the French drain system. These systems will treat storm water and convey flows to a small diameter lower outlet orifice. Once flows have been routed by the outlet structures, flows will then discharge independently from each basin to the receiving POC discharge location . The biofiltration basins were modeled using the biofiltration LID module within SWMM. Please refer to Appendix 1 of the Technical Memorandum: Determination of Pre-and Post-Developed 100-year Peak Flow for details explaining the biofiltration module . The DCV for DMA 1 has been calculated based on the proposed impervious roof and landscape areas draining to each BMP. Worksheet B.5-1 in Attachment 1d further demonstrates that the full DCV can be treated within the biofiltration BMPs. Based on recommendations from the Geotechnical report, infiltration from the biofiltration basins is not considered to be appropriate for the project. The bottom of the basins will be lined with an impermeable liner to prevent infiltration of storm water. See copy of Geotechnical report titled "Geotechnical Investigation, Proposed Afton Way Residential Development for 2200 Afton Way, Carlsbad, CA", by Leighton and Associates, Inc. in Attachments section. 22 • • • .. • • • • .. .. • • 411 • --.. .. .. .. • .. - Structural BMP ID No. Basin 1 DWG Sheet No. Type of structural BMP: D Retention by harvest and use (HU-1) D Retention by infiltration basin (INF-1) D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3) D Partial retention by biofiltration with partial retention (PR-1 ) IZI Biofiltration (BF-1) D Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below) D Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below) D Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below) D Detention pond or vault for hydromodification management D Other (describe in discussion section below) Purpose: D Pollutant control only D Hydromodification control only IZI Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP D Other (describe in discussion section below) Discussion (as needed): Basin 1 will be used for pollutant control and peak flow control for the project stormwater runoff. The outlet structure for Basin 1 has been designed based on results from the Technical Memorandum: SWMM Modeling for Hydromodification Compliance for Afton Way, dated April 9, 2015 from Tory R. Walker Engineering under separate cover (see Attachments section of this Report for copy of Technical Memorandum). See Attachment 1 for DCV calculations. 23 ---------·--- • • • • - • • Ill - -.. • .. .. 41 .. .. --- Structural BMP ID No. Basin 2 DWG Sheet No. Type of structural BMP: D Retention by harvest and use (HU-1) D Retention by infiltration basin (INF-1) D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3) D Partial retention by biofiltration with partial retention (PR-1) !ZI Biofiltration (BF-1) D Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below) D Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below) D Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below) D Detention pond or vault for hydromodification management D Other (describe in discussion section below) Purpose: D Pollutant control only D Hydromodification control only !Z1 Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP D Other (describe in discussion section below) Discussion (as needed): Basin 2 will be used for pollutant control and peak flow control for the project stormwater runoff. The outlet structure for Basin 2 has been designed based on results from the Technical Memorandum: SWMM Modeling for Hydromodification Compliance for Afton Way, dated April 9, 2015 from Tory R. Walker Engineering under separate cover (see Attachments section of this Report for copy of Technical Memorandum). See Attachment 1 for DCV calculations. 24 -.. • - -• -• • • .. .. -.. .. -- .. -- • • -.. • .. .. • ATTACHMENT 1 BACKUP FOR PDP POLLUTANT CONTROL BMPS Check which Items are Included behind this cover sheet: Attachment Contents Checklist Seauence Attachment 1 a OMA Exhibit (Required) [8J Included Attachment 1 b See OMA Exhibit Checklist on the back of this Attachment cover sheet. (24"x36" Exhibit typically required) Tabular Summary of DMAs Showing OMA ID matching OMA Exhibit, OMA Area, and OMA Type (Required)* *Provide table in this Attachment OR on OMA Exhibit in Attachment 1a LJ Included on OMA Exhibit in Attachment 1 a [8J Included as Attachment 1 b, separate from OMA Exhibit Attachment 1c Form 1-7, Harvest and Use Feasibility ~ Included Attachment 1 d Screening Checklist (Required unless D Not included because the entire the entire project will use infiltration project will use infiltration BMPs BMPs) Refer to Appendix B.3-1 of the BMP Design Manual to complete Form 1-7 . Form 1-8, Categorization of Infiltration Feasibility Condition (Required unless the project will use harvest and use BMPs) Refer to Appendices C and D of the BMP Design Manual to complete Form 1-8. ~ Included D Not included because the entire project will use harvest and use BMPs Attachment 1 e Pollutant Control BMP Design ~ Included Worksheets / Calculations (Required) Refer to Appendices B and E of the BMP Design Manual for structural pollutant control BMP design guidelines 25 -- • • -.. • -.. • • ------- --.. ---- - -- Attachment 1 a DMA Exhibit 26 DMA SURFACE TABULATION TO SUPPORT BIOFILTRATION OF DESIGN CAPTURE VOLUME (DCV) DETERMINATION DMA Impervious Area Tabulation Surface Name Surface Ty e RI C:onYcntiona\ Roof and Patio l'CCl Concrete l)nYewav R2 ConYcnaoml Roof ,md Patio PCC2 Concrete DriYcway R3 C(Hwentional Roof and Patio PCC3 Concrete DnYew;iv R4 C:om·cntional Roof and Patio PCC4 Concrete D riYewav RS Conn:'ntional Roof and Patio recs R6 Cotwemioml Roof ,md Patio PCC:6 Concrete Dri\·cwa · R7 C:01wcntional Roof and Patio PCC7 Concrete DriYcwav RS C:oiwcntion;i.l Roof and Patio PCC:8 PCC9 rc:crn Concrete Street Total Im ervious Area (fl) OMA Pervious Area Tabulation Surface N rune Surface T , e L1 Land sea C 1,2 J .andsca e 1,3 J ,and sci e IA Land sea C 1.5 l.:1nd ::-rn e u, J ,andsrn C L7 LandsGt 1c LS J ,:1ndsc1 e Total Pervious Area (fl) Total DMA(A Total Im ervious Area (fi2) /Total DMA (ft2) = Percent Impervious Soil T, Area Weighted Runoff Factor ("C") per Appendix B.1 and B.2* 85th Percentile Rainfall I) / / / ! :PROPOSED BROW DITCH · SM 1 3,568 S \ -'PROPOSE. ·BROW DITC/-j \ ' ' ' ' ' ' L10 "' "' "' ' ---\ DMAl 2 Aiea (ft 2,505 1,663 2,804 775 3,833 6,815 3,856 2,398 2,568 2,}5:16 2,810 3,082 4,377 3,948 3,754 496 1,782 13,145 62,947 Area ft' r,, 115 8,950 7,930 9,301 7,302 10,(,07 9,958 20,915 81,078 144,025 B & D 0.45 U.6 ' . \ . \ ' , ' ' , \ PROJECT ' . , . '' i\ \BO~~DA '' ' ',) t 'i K:\Civil 3D\1326\PROD\DWG\HYDRO & SWMP\1326-DMA-HMP EXHIBIT.dwg, 7/18/2017 2:51:32 PM \ \ \ I \ ·~. ,1,....._.,,~~~1-... y I I • • ,,,_.'--, . ,-, .. ' . . . , -. ' • . ' ' ' ' \ EXIST._/ BROW DITCH ' ' ' ' ' ', , \\ l 'y \ 1.--,· -PROJECT' \ BOUNQARY., \ \ .\ \ \ ' i ) ·"---~-·-- L6 PRO OSED ( i:i~ [ID \ \ \ .L..--"'r"7 \ LOT6 R6 \ \ \ \ ~-~ DRAINAGE MANAGEMENT AREA EXHIBIT \ ~ AFTON WAY SUBDIVISION, CARLSBAD, CA \ \ / .,....-1 \ =Df<"--4"\ D-5 I SD-7! I 7 7 I , I L---1 • ' I ' ' ' ' '"°'--PROJECT , BOUNDARY I ' ' • ·- 1 L J __ ;_ ~ I I I I PROJECT CHARACTERISTICS SOIL TYPE B & D PROJECT AREA 4.94 ACRES DISTURBED AREA 3.37 ACRES PROPOSED IMPERVIOUS AREA 1.26 ACRES PROPOSED PER~OUS AREA 2.11 ACRES GENERAL NOTES 1. BIOFIL TRATION BASINS TO BE USED AS COMBIN ED POLLUTANT CONTROL AND FLOW CONTROL BMPS. 2. BIOFIL TRA TION BASINS TO INCLUDE A PERFORATED UNDERDRAIN PIPE WITH A LOW FLOW ORIFICE BELOW THE BOTTOM OF THE GROWING MEDIUM. BIOFIL TRATION BASINS TO 1,N CLUDE AN IMPERMEABLE LINER - BELOW THE GRAVEL LA YER TO RESTRICT INFILTRATION. 3. THE OUTLET STRUCTURE FOR BASIN 1 AND BASIN 2 HAVE BEEN DESIGNED BASED ON RESULTS FROM THE "TECHNICAL MEMORANDUM: SWMM MODELING FOR HYDROMODIFICATION COMPLIANCE FOR AFTON WAY, CITY OF CARLSBAD, RE~SED JUNE 17, 2015", PREPARED BY TORY R. WALKER ENGINEERING. SEE SWQMP FOR COPY OF REPORT. SOURCE CONTROL BMPS: I SC-1 I PREVENTION OF ILLICIT DISCHARGES IN TO THE MS4 1sc-21 STORM DRAIN STENCILIN G AND SIGNAGE !SC-6! [Al [ill [rJ [ID ADDITIONAL BMPS BASED ON POTENTIAL RUNOFF POI I UTANTS: ON-SITE STORM DRAIN INLETS NEED FOR FUTURE INDOOR & STRUCTUR AL PEST CON TROL LANDSCAPE/OUIDOOR PESTICIDE USE PLAZAS, SIDEWALKS, DRIVEWAYS, AND PARKING LOTS LID AND SITE DESIGN: !SD-1 ! MAINTAIN NATURAL DRAINAGE PATHWAYS AND HYD ROLOGIC FEATURES SD-2 SD-3 SD-4 SD-5 SD-7 CONSERVE NATURAL AREAS, SOILS, AND VEGETATION MINIMIZE IMPERVIOUS AREA MINIMIZE SOIL COMPACTION IMPER~OUS AREA DISPERSION LANDSCAPING WITH NATIVE OR DROUGH T TOLERANT SPECIES PROHIBITIVE DUMPING SIGNAGE LEGEND DMA DRAINING TO IMP SELF MIT/GA TING DMA POINT OF CONCENmA TION OMA LIMIT FLOW DIRECTION BIOFIL mA TION BASIN CONCRETE CUL -DE-SAC IMPERVIOUS DRIVEWAY RIP RAP ENERGY DISS/PATER PROJECT BOUNDARY BROW DITCH SOIL CLASS/FICA TION BOUNDARY DMA 1 SM 1 POC 1 [ ' . 'j I I ~ SELF-MITIGATING DMAS: VEGETATION IN THE NATURAL OR LANDSCAPE AREA IS NATIVE OR NON -NATIVE DROUGHT TOLERANT SPECIES. SOILS ARE UNDISTURBED NATIVE TOPSOIL, OR DISTURBED SOILS HAVE BEEN AMENDED AND AERATED TO PROMOTE WATER RETENTION CHARACTERISTICS EQUIVALENT TO UNDISTURBED NATIVE TOPSO IL. INCIDENTAL IMPERVIOUS AREAS ARE LESS THAN 5 PERCENT OF THE SELF-MITIGATING AREA. IMPER~OUS AREAS CALCULATED WITHIN THE SELF-MITIGATED AREA SHOULD NOT BE HYDRAULICALLY CONNECTED TO OTHER IMPER~OUS AREAS UNLESS IT IS A STORM WATER CONVEYANCE SYSTEM (SUCH AS BROW DITCHES). THE SELF-MITIGATING AREA IS HYDRAULICALLY SEPARATE FROM DMAS THAT CONTAIN PERMANENT STORM WATER POLLUTION CONTROL BMPS. TABULATION OF SELF-MITIGATING DMAS Surface Name Self-Miti ating DMA Name Aiea (ft') L IO SM-1 23,568 SM-2 45,9?i5 L12 5:l,791 1,13 SM -4 16,018 Total Sclf-l\litigating Areas 139,312 TYPE B BROW DITCH --ll PER SDRSD D-75 >ffl' 220' -.... DEEP ROOTED, DENSE, DROUGHT 50' SLOT ORIFICE TO ALLOW 100 YR PREDEVELOPMENT FLOW 18" ENGINEERED SOIL MIX -..._TOJ.fFIANT PLANTING SUITABLE ----..., FOR WEbL. DRAINED SOIL _ _ \ TYPE G-1 CATCH BASIN WITH GRATED INLET TW 215' BASIN 1 FOR POST DEVELOPMENT 100YR FLOW 214.25 RIM --.... EXIST GROUND TYPE G-1 CATCH BASIN -..JYITH GRATED INLET FOR POST DEITTOPMENT 100YR FLOW 7' V2 STORAGE LAYER --..., (2"-PEA GRAVEL OVER ..... 10"-J/4" CRUSHED ROCK) 212.5 ' ,n,-""',l_i.;~ 209.25' "-':::: 270' ..____ ~--- 6" PERFORATED PVC UNDERDRA IN PIPE PLACE PIPE WITH PERFORA T/ONS ATTHE INVERT BW 210 '---,-..,...,..,..-t, IMPERMEABLE LINER THROUGHOUT---__; RESTRICTOR PLATE TO LIMIT FLOW FROM V2 STORAGE AREA, 2.25" DRAIN DOWN HOLE 18" ENGINEERED SOIL MIX PER G.1.5.J.1 OF BMP DESIGN MANUAL---- STORM DRAIN CASING-~ 2075' . , 12" HOPE OUfLET PIPE FROM RISER/BASIN 1 IMPERMEABLE LINER THROUGHOUT SECTION· '½-A" BIOFILTRATION BASIN DETAIL 25' o· NOT TO SCALE 50' 100' 150' SCALE: 1" = 50' b~A,lnc. land planning, cMI engineering, survey!ng 5115 AVEN IDA ENCINAS SUITE "L" CARLSBAD, CA. 92008-4387 (760) 931-8700 DRAINAGE MANAGEMENT AREA EXHIBIT AFTON WAY SUBDIVISION CARLSBAD, CA - - -.. --.. .. - -... • .. -.. • .,. .. --• -----.... -... ---.. - • Attachment 1 b Tabular Summary of DMAs and Design Capture Volume Calculations 27 --.. -.. • -Surface Name R1 Conventional Roof and Patio 2,505 • PCC1 Concrete Drivewa 1,663 R2 Conventional Roof and Patio 2,S04 -PCC2 Concrete Driveway 775 • R3 Conventional Roof and Patio 3,S33 PCC3 Concrete Driveway 6,S15 -R4 Conventional Roof and Patio 3,S56 .. PCC4 Concrete Driveway 2,39S R5 Conventional Roof and Patio 2,56S .. PCC5 Concrete Drivewa 2,336 ... R6 Conventional Roof and Patio 2,S10 PCC6 Concrete Drivewa 3,0S2 -R7 Conventional Roof and Patio 4,377 .. PCC7 Concrete Drivewa 3,94S RS Conventional Roof and Patio 3,754 .. PCCS Concrete Drivewa 496 -PCC9 Concrete Drivewa 1,7S2 PCC10 Concrete Street 13,145 • • -.. L1 .. L2 L3 7,930 • L4 9,301 • LS 7,302 L6 10,607 .. L7 9,95S LS 20,915 .. --... -- .... --28 --... ••'• ~•~<••a---•---•"'""' .,,.-____ _... _____ .. ,.,a,.-·~-·, --.. ---- "' • ,. .. ... -.. -... --.. -.. • -• • ------ • -• -·• - """ * Note: Area weighted runoff factor calculated per Appendix B.1.1 of the BMP DM. Runoff factors for surfaces per Table B.1-1. See summary of runoff factors used below: Roof Concrete 0.9 Amended soils or Landsca e 0.1 29 - ··--- • • -- • • -... .. .. .. ... - • -• -- • • • 41' -... • -.. .. • • -30 • .. .... -- • • • - • .. • 111 .. -.. .. .. • .. .. -----.. • • .. .. ----.. • .. 31 111 -., .. .. • DMA Classification Subtotal DMA .. DMAs 139,312 0 0 0 Surfaces Dr .. DMAs 0 0 0 Bioretention IMPs 0 0 0 Flow Thro h Planter IMPs 2 144,025 3.31 • Infiltration IMP 0 0 0 • 0 0 0 0 0 0 0 0 0 Wet Pond 0 0 0 .. Constructed Wetland 0 0 0 0 0 0 -Inlet Filter 0 0 0 ... Areas Not Feasible to Treat 0 0 0 .. Total Pro·ect DMA 283,337 6.50 • Total Parcel Area 214,993 4.94 Comment • • • .. • -32 ... - ... .. • • • • ... • • .. • • • -.. .. .. • .. Attachment 1 c Form 1-7, Harvest and Use Feasibility Screening Checklist 1. Is there a demand for harvested water (check all that apply) at the project site that is reliably present during the wet season? ~ Toilet and urinal flushing ~ Landscape irrigation D Other: 2. If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours. Guidance for planning level demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section B.3.2 . Modified E1WU = ETowetX [!L(PF x HA)/IE] + SLA] x 0.015 Using an average value for HA over the 8 residential lots and Low Plant Water Use (per Table B.3-2); Modified E1WU = 2.7 x [[(0.2 x 83,708)/0.9] + O] x 0.015 Modified E1WU= 753 (Total pervious area= 83,708 sf) 3. Calculate the DCV using worksheet B-2.1. DCV = ~3_2=3=8 ___ (cubic feet) 3a. Is the 36 hour demand greater than or equal to the DCV? D Yes I C8] No -0, c::> Harvest and use appears to be feasible. Conduct more detailed evaluation and sizing calculations to confirm that DCV can be used at an adequate rate to meet drawdown criteria. 3b. Is the 36 hour demand greater than 0.25DCV but less than the full DCV? D Yes I C8] No -0, c::> Harvest and use may be feasible. Conduct more detailed evaluation and sizing calculations to determine feasibility. Harvest and use may only be able to he used for a portion of the site, or (optionally) the storage may need to be upsized to meet long term capture targets while draining in longer than 36 hours . 33 3c. Is the 36 hour demand less than 0.25DCV? C8] Yes -0, Harvest and use is considered to be infeasible . .. • • • • • • • --... -- .. • .. -- - .. -• • Is harvest and use feasible based on further evaluation? D Yes, refer to Appendix E to select and size harvest and use BMPs . C8J No, select alternate BMPs Harvest and use BMPs are considered infeasible. Drought tolerant landscape, as proposed in SD-7 in Form E-36, requires low plant water use. Project will implement other LID strategies such as impervious area dispersion. The full DCV can be treated in the proposed biofiltration basins. Property owners will be encouraged to use rain barrels after construction to reduce runoff volumes . 34 -- • • .. ---• .. ... • fl .. • .. ---... ... .. .. ... • 1 Attachment 1 d Form 1-8, Categorization of Infiltration Feasibility Condition Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D . Provide basis: No Percolation testing was performed in the location of the proposed biofiltration basins to evaluation suitability of the site for infiltration of storm water. According to the Geotechnica/ Investigation, 2200 Afton W ~, Carlsbad, CA by Leighton and Associates, Inc., "The results of the percolation test indicated that the site soils had a percolation rate of greater than 125 minutes per inch (mpi). Generally a percolation rate less than 120 mpi is considered necessary to consider a site suitable for onsite infiltration of storm water. Additionally the presence of shallow clayey sand and clay materials present in much of the site would be expected to impede infiltration and a 30-mil HDPE should be considered to line any proposed infiltration basin." 2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 . Provide basis: Yes According to the Geotechnical Investigation, "the presence of shallow clayey sand and clay materials present in much of the site would be expected to impede infiltration." Clayey sand and clay materials have a high shrink-swell potential, a high water table, a claypan or clay layer at or near the surface, and are shallow over nearly impervious material. These soils have a very slow rate of water transmission. It is also noted by geotechnical engineer that saturation of storm water into the proposed slopes can result in shallow slope failure. But provided that the recommendations contained in the geological report are incorporated into the final design, subsurface and surface water are not anticipated to affect site development. 35 -... -• • .. .. .. - -.. ----.. .. -- • - .. - .. • • • - 41 3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3 . Provide basis: No Although groundwater was not encountered within the geotechnical report, an infiltration rate greater than 0.5 inches per hour cannot be achieved. 4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: No Although there are no potential water balance issues or contaminated groundwater, an infiltration rate greater than 0.5 inches per hour cannot be achieved. Part1 Result * If all answers to rows 1 -4 are ''Yes" a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration If any answer from row 1-4 is ''No", infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a "full infiltration" design. Proceed to Part 2 36 No -... ---.. -.. • .. .. --- --.. • .. • • .. • --------- -- 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and AppendixD. Provide basis: Yes Per the Geotechnical Investigation, "percolation test indicated that the site soils had a percolation rate of greater than 125 minutes per inch (mpi). Generally a percolation rate less than 120 mpi is considered necessary to consider a site suitable for onsite infiltration of storm water." Additionally the presence of shallow clayey sand and clay materials present in much of the site would be expected to impede infiltration and a 30-mil HDPE should be considered to line any proposed infiltration basin." Therefore the soil will allow for a percolation rate greater than 125 mpi, although the rate is unacceptable for a suitable infiltration basin. See Attachment 8 of Technical Memorandum: SWMM Modeling for Hydromodificaiton Compliance of: Afton Way, Carlsbad, CA for copy of geotechnical study . 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 . Provide basis: No Based on recommendations from the geotechnical report, infiltration basins could "potentially create adverse perched ground water conditions both on-site and off-site. Therefore given the site geologic conditions, impermeable subsurface material, and project type, infiltration type LID measures are not considered to be appropriate for this site and project, 30 mil HDPE Liners should be used where detention areas are proposed near slopes or retaining walls, near buildings, or over utilities." 37 -... .. - • .. • .. .. .. .. - - • .. • • .. --.. ------... 7 Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: See comment to Criteria 6 . 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: No Yes The project will mimic existing drainage conditions. There are no downstream water rights applicable. If all answers from row 5-8 are yes then partial infiltration design is potentially Part 2 feasible. The feasibility screening category is Partial Infiltration . Result If any answer from row 5-8 is no, then infiltration of any volume is considered * to be infeasible within the drainage area. The feasibility screening category is No Infiltration . 38 No Infiltration -.. -.. • • .. .. • ... - .. .. • • .. • -.. • • -.. --.. -- - -.. Attachment 1e Pollutant Control BMP Design Worksheets / Calculations 39 --- • • • ... .. .. • .. .. .. • -.. -• .. .. -... -.. .. .. • BMP1 6 Required depth of gravel below the underdrain [Line 4 / Line 5] inches 7 Assumed surface area of the biofiltration BMP 2,290 sq-ft 8 Media retained pore space in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 cubic-feet 10 DCV that requires biofiltration [Line 1 -Line 9] 3,238 cubic-feet 17 18 endix B.1 and B.2 26 27 ine 21, Line 23 , Line 26 Used BMP Foot rint 40 .. ... .. .. .. • .. .. .. • • .. ... 1) The biofiltration basin has be designed in accordance with City of Carlsbad BMP Design Manual (BMP DM) sizing criteria, which includes minimum BMP footprint and draw down requirements. The OMA has been delineated based on onsite drainage patterns and BMP locations. Based on Chapter 3 Section 3.3.3 of the BMP DM, a single OMA may not drain to more than one BMP. Therefore the biofiltration BMP must be sized to treat the DCV from the total drainage area draining to the BMP. Used BMP Footprint= 2,290 sf= 1,805 sf (Basin 1) + 485 sf (Basin 2) 2) Since partial infiltration is considered infeasible, the infiltration rate in Llne 2 is set to 0 inches/hour. Therefore the volume retained by the BMP is essentially O cubic-feet and the DCV that requires biofiltration, Llne 10, is equal to Llne 1. 41 .. - • - - .. • • - - - - -.. - BlofHtration Criteria Checldist The applicant must provide documentation of compliance with each criterion in this checklist as part of the project submittal. The right column of this checklist identifies the submittal information that is recommended to document compliance with each criterion. Biofiltration BMPs that substantially meet all aspects of Fact Sheets PR-1 or BF-1 should still use this checklist; however additional documentation (beyond what is already required for project submittal) should not be required. 1. Biofiltration BMPs must be allowed to be used only as described in the BMP selection process based on a documented feasibility analysis. Intent: This manual defines a specific prioritization of pollut«nt treatment BMPs, where BMPs that retain water (retained includes evapotranspired, infiltrated, and/ or harvested and used) must be used before considering BMPs that have a biofiltered discharge to the MS4 or surface waters. Use of a biofiltration BMP in a manner in conflict with this prioritization (i.e., without a feasibility analysis justifying its use) is not permitted, regardless of the adequacy of the sizing and design of the system. ·············"·······--··········"·"····--•""'""''"""'""""'' .......................................................... . ............................... . The project applicant has demonstrated that it D £ 'bill' al • d findin • . . . . ocument east ty an ys1s an gs 1n 1s not technically feasible to retam the full DCV th SWQMP A dix C . e per ppen . ons1te . ----------•• --•-----------------•---•••••---•--M••---••• 00 2. Biofiltration BMPs must be sized using acceptable sizing methods . Intent: The MS4 Permit and this manual defines specific sizing methods that must be used to size biofiltration BMPs. Sizing of biofiltration BMPs is a fundamental factor in the amount of storm water that can be treated and also influences volume and pollutant retention processes. The project applicant has demonstrated that biofiltration BMPs are sized to meet one of the biofiltration sizing options available (Appendix B). Submit sizing worksheets (Appendix B) or other equivalent documentation with the SWQMP. 3. Biofiltration BMPs must be sited and designed to achieve maximum feasible infiltration and evapotranspiration. Intent: Various decisions about BMP placement and design influence how much water is retained via infiltration and evapotranspiration. The MS4 Permit requires that biofiltration BMPs achieve maximum feasible retention (evapotranspiration and infiltration) of storm water volume. -... .. • • • 1111 • -.. • • .. - • • --.. -- 111 - . ..... ·--·····················-·-··-····-···--·-···--~ . ····-·•···· ...... ,. ...... ,, ................................. ,. ............................ . □ □ □ Ix] The biofiltration BMP is sited to allow for maximum infiltration of runoff volume based on the feasibility factors considered in site planning efforts. It is also designed to maximize evapotranspiration through the use of amended media and plants (biofiltration designs without amended media and plants may be permissible; see Item 5) . ····--·--····-···················--·---••'-----•---------···--·--- For biofiltration BMPs categorized as "Partial Infiltration Condition," the infiltration storage depth in the biofiltration design has been selected to drain in 36 hours or an alternative value shown to maximize infiltration on the site. ........................ ······•·········"'''''''''"''""'''''"" ..... For biofiltration BMP locations categorized as "Partial Infiltration Condition," the infiltration storage is over the entire bottom of the biofiltration BMP footprint. For biofiltration BMP locations categorized as "Partial Infiltration Condition," the sizing factor used for the infiltration storage area is not less than the minimum biofiltration BMP sizing factors calculated using Worksheet B.5.3. ........................................................................................................ An impermeable liner or other hydraulic restriction layer is only used when needed to avoid geotechnical and/ or subsurface contamination issues in locations identified as "No Infiltration Condition." ..... ~---· ........ ,. .............. , .• _._,,,~--·· •.•.•..•.......•.... ·•••·•····••· •...• ,. ..... ,. .•• ",. .... ,.. .. --········--···----··· The use of "compact" biofiltration BMP design is permitted only in conditions identified as "No Infiltration Condition" and where site- specific documentation demonstrates that the use of larger footprint biofiltration BMPs would be infeasible. Document site planning and feasibility analyses in the SWQMP per Section 5.4. Included documentation of estimated infiltration rate per Appendix D; provide calculations using Appendix B.4 and B.5 to show that the infiltration storage depth meets this criterion. Note, depths that are too shallow or too deep may not be acceptable. .. ......................... . Document on plans that the infiltration storage covers the entire bottom of the BMP (i.e., not just underdrain trenches); or an equivalent footprint elsewhere on the site. Provide a table that compares the minimum sizing factor from Appendix B.5 to the provided sizing factor. Note: The infiltration storage area could be a separate storage feature located downstream of the biofiltration BMP, not necessarily within the same footprint. If using an impermeable liner or hydraulic restriction layer, provide documentation of feasibility findings per Appendix C that recommend the use of this feature. Provide documentation of feasibility findings that recommend no infiltration is feasible. Provide site-specific information to demonstrate that a larger footprint biofiltration BMP would not be feasible . "• ••••••"•'"".. •••••••••••••••••••-•••••••••••• •••••••••••••• •••••• • ••• ••••••••••••-•• ••••• ••••••••~•••• •• • ••••• •••••••••••••••••••••••••••-•••• 4. Biofiltration BMPs must be designed with a hydraulic loading rate to maximize pollutant retention, preserve pollutant control processes, and minimize potential for pollutant washout. Intent: Various decisions about biofiltration BMP design influence the degree to which pollutants are retained. The MS4 Permit requires that biofiltration BMPs achieve maximum feasible retention of storm water pollutants. - .. .. • .. • • • • • .. .. • .. --.. -----.. IK1 □ Media selected for the biofiltration BMP meets minimum quality and material specifications per 2016 City Storm Water Standards or County LID Manual, including the maximum allowable design filtration rate and minimum thickness of media . OR Alternatively, for proprietary designs and custom media mixes not meeting the media specifications contained in the 2016 City Storm Water Standards or County LID Manual, field scale testing data are provided to demonstrate that proposed media meets the pollutant treatment performance criteria in Section F.1 below. Provide documentation that media meets the specifications in 2016 City Storm Water Standards or County LID Manual. Provide documentation of performance information as described in Section F.1. ,,_,,_,_,_,.,,._. • .,c•••ere•»••--••--~•'s>•,-••-----•---------•,-•••""'"""'"•""'"'''""''''•••• IK1 To the extent practicable, filtration rates are outlet controlled ( e.g., via an underdrain and orifice/weir) instead of controlled by the infiltration rate of the media . The water surface drains to at least 12 inches 1K] below the media surface within 24 hours from the end of storm event flow to preserve plant health and promote healthy soil structure. If nutrients are a pollutant of concern, design Ix] of the biofiltration BMP follows nutrient- sensitive design criteria. ............... Media gradation calculations or geotextile Ix] selection calculations demonstrate that migration of media between layers will be prevented and permeability will be preserved. Include outlet control in designs or provide documentation of why outlet control is not practicable. . ......................... .. Include calculations to demonstrate that drawdown rate is adequate. Surface ponding drawdown time greater than 24-hours but less than 96 hours may be allowed at the discretion of County staff if certified by a landscape architect or agronomist . . ................... ··············•···············"·······"··•"''''''"'''''"''''''''''''''''''''''''••········ Follow specifications for nutrient sensitive design in Fact Sheet BF-2. Or provide alternative documentation that nutrient treatment is addressed and potential for nutrient release is minimized . Follow specification for choking layer or geotextile in Fact Sheet PR-1 or BF-1. Or include calculations to demonstrate that choking layer is appropriately specified . . s. Bi~filtratl~n·BMPs must i,e ·designed to promote.app~oprlite biological acti~ty t~ support and maintain treatment processes. Intent: Biological processes are an important element of bioftltration performance and longevity . -.. -.. .. ---------.. -- - • .. .. .. - .. --.. .. - --- 00 [x] □ ····-·······,. .... _,, _____ ............. ·• . ··············---···., Plants have been selected to be tolerant of project climate, design ponding depths and the treatment media composition. Provide documentation justifying plant selection. Refer to the plant list in Appendix E.20. Provide documentation describing irrigation Plants have been selected to minimize irrigation requirements for establishment and long term requirements. Plant location and growth will not impede expected long-term media filtration rates and will enhance long term infiltration rates to the extent possible. If plants are not part of the biofiltration design, other biological processes are supported as needed to sustain treatment processes (e.g., biofilm in a subsurface flow wetland). operation. Provide documentation justifying plant selection. Refer to the plant list in Appendix E.20. For biofiltration designs without plants, describe the biological processes that will support effective treatment and how they will be sustained. •••••-no•••••-•••»>••••"•••••-••••-••••••--••••-»•••• .. •••• 6. Biofiltration BMPs must be designed with a hydraulic loading rate to prevent [x] [xi □ erosion, scour, and channeling within the BMP. Intent: Erosion, scour, and/ or channeling can disrupt treatment processes and reduce biofiltration effectiveness. ------••--=•••w,-•mY•••<<>v,>••w_,, .. _ _,_, ___ , __ Scour protection has been provided for both sheet flow and pipe inflows to the BMP, where needed. Provide documentation of scour protection as described in Fact Sheets PR-1 or BF-1 or approved equivalent. •••••• •»•••• ............ • .. •••••••••••••••••••••••••••n--•o --••••• ••••••M••••M ..... eu ... •• ,>OWOO»o ..... , •--•••---••••••• • e OOOUOnOOO•<,>OO, -••••-••••••••• .. ••••••wM••• .. O>>Oo •••• .. •••»>• .. n•••••~••••••'""''' m<H''°><O•• • ,<,»>O<CH>Oo••noo•• 0 Where scour protection has not been provided, Provide documentation of design checks for flows into and within the BMP are kept to non-erosive velocities as described in Fact Sheets erosive velocities. PR-1 or BF-1 or approved equivalent. For proprietary BMPs, the BMP is used in a manner consistent with manufacturer guidelines and conditions of its third-party certification19 (i.e., maximum tributary area, maximum inflow velocities, etc., as applicable) . Provide copy of manufacturer recommendations and conditions of third-party certification. 19 Certifications or verifications issued by the Washington Technology Acceptance Protocol-Ecology program and the New Jersey Corporation for Advanced Technology programs are typically accompanied by a set of guidelines regarding appropriate design and maintenance conditions that would be consistent with the certification/verification ... - .. -• • • • • • .. • • • -... .. -.. • • • -- 7. Biofiltration BMP must include operations and maintenance design features and planning considerations for continued effectiveness of pollutant and flow control functions. Intent: Biofiltration BMPs require regular maintenance in order provide ongoing function as intended. Additionally, it is not possible to foresee and avoid potential issues as part of design; therefore plans must be in place to correct issues if they arise. The biofiltration BMP maintenance plan describes specific inspection activities, regular/periodic maintenance activities and specific corrective actions relating to scour, erosion, channeling, media clogging, vegetation health, and inflow and outflow structures. Include maintenance plan with the SWQMP as described in Chapter 7. •••• •••••••••••••••••••••••••••• ••~.-••-••••••~-... ••••••---••---••••• m••••os• -,•m••••••• """""""••••m•••••--•••" "'"" . ................... , ..... _.,. .... ,,,. ... ,, ..... ,, ....................... ,, .... ,, ..... ,, ..... ,, .. .. 1K] □ Adequate site area and features have been provided for BMP inspection and maintenance access . For proprietary biofiltration BMPs, the BMP maintenance plan is consistent with manufacturer guidelines and conditions of its third-party certification (i.e., maintenance activities, frequencies) . Illustrate maintenance access routes, setbacks, maintenance features as needed on project water quality plans. Provide copy of manufacturer recommendations and conditions of third-party certification. t I , I I t I I I I I a • I I I I I A I '-. • • • • a , ' . I I I t I I 1 Potential Sources of Runoff Pollutants 2 Permanent Controls-Show on Drawings 00 A. Onsite storm drain I 00 Locations of inlets. inlets □ Not Applicable 3 Permanent Controls-List in Table and Narrative 4 Operational BMPs-Include in Table and Narrative 00 Mark all inlets with the words "No 00 Maintain and periodically repaint Dumping! Flows to Bay" or similar. or replace inlet markings. See ste~cil template provided in 00 Provide storm water pollution Appendix 1-4 prevention information to new site owners, lessees, or operators. 00 See applicable operational BMPs in Fact Sheet SC-44, "Drainage System Maintenance," in the CASQA Storm Water Quality Handbooks at wvlw.casqa.org/resources/bmp-handbooks/municipal-bmp-handbook. 00 Include the following in lease agreements: "Tenant shall not allow anyone to discharge anything to storm drains or to store or deposit materials so as to create a potential discharge to storm drains." I I • • • • i • i I 1 Potential Sources of Runoff Pollutants □ B. Interior floor drains and elevator shaft sump pumps Iii Not Applicable □ C. Interior parking garages !xi Not Applicable !RI D1. Need for future indoor & structural pest control D Not Applicable I I l I I I i I t I 2 Permanent Controls-Show on Drawings I I ' ' • • • • • • I I I I I I I • 3 Permanent Controls-List in Table and Narrative □ State that interior floor drains and elevator shaft sump pumps will be plumbed to sanitary sewer. □ State that parking garage floor drains will be plumbed to the sanitary sewer. 4 Operational BMPs-Include in Table and Narrative □ Inspect and maintain drains to prevent blockages and overflow. □ Inspect and maintain drains to prevent blockages and overflow. !RI Note building design features that I !RI discourage entry of pests. Provide Integrated Pest Management information to owners, lessees, and operators. l I . ' • • • • t I 1 Potential Sources of Runoff Pollutants 00 D2. Landscape/ Outdoor Pesticide Use D Not Applicable i I I I a I I I • • I I I I l I I I l I 2 Permanent Controls-Show on Drawings 00 00 00 Show locations of existing trees or areas of shrubs and ground cover to be undisturbed and retained. Show self-retaining landscape areas, if any. Show storm water treatment facilities. 3 Permanent Controls-List in Table and Narrative State that final landscape plans will I 00 accomplish all of the following. 00 Preserve existmg drought tolerant I 00 trees, shrubs, and ground cover to the maximum extent possible. 00 Design landscaping to minimize irrigation and runoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to storm water pollution. 00 Where landscaped areas are used to retain or detain storm water, specify plants that are tolerant of periodic saturated soil conditions. 00 Consider using pest-resistant plants, especially adjacent to hardscape. 00 To ensure successful establishment, select plants appropriate to site soils, slopes, climate, sun, wind, rain, land use, air movement, ecological consistency, and plant interactions. loo I I I I I I I I 4 Operational BMPs-Include in Table and Narrative Maintain landscaping using minimum or no pesticides. See applicable operational BMPs in Fact Sheet SC-41, "Building and Grounds Maintenance," in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources /bmp -handbooks/municipal-bmp-handbook. Provide 1PM information to new owners, lessees and operators. I I j • l I I I a I 1 Potential Sources of Runoff Pollutants □ E. Pools, spas, ponds, decorative fountains, and other water features. Iii Not Applicable □ F. Food service Iii Not Applicable l I □ □ □ I I ._ I • • • • 2 Permanent Controls-Show on Drawings Show location of water feature and a sanitary sewer cleanout in an accessible area within 10 feet. For restaurants, grocery stores, and other food service operations, show location (indoors or in a covered area outdoors) of a floor sink or other area for cleaning floor mats, containers, and equipment. On the drawing, show a note that this drain will be connected to a grease interceptor before discharging to the sanitary sewer. • I • • • j • • . , □ □ □ 3 Permanent Controls-List in Table and Narrative If the local municipality requires pools to be plumbed to the sanitary sewer, place a note on the plans and state in the narrative that this connection will be made according to local requirements. Describe the location and features of the designated cleaning area. Describe the items to be cleaned in this facility and how it has been sized to ensure that the largest items can be accommodated. • • I I I j I f 4 Operational BMPs-Include in Table and Narrative □ See applicable operational BMPs in Fact Sheet SC-72, "Fountain and Pool Maintenance," in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources/bm p-handbooks/municipal-bmp-handbook. t I A I I I I . a • I. • t I 1 Potential Sources of □ G. Refuse areas ll9 Not Applicable t • I f . , A t ._ I • • • • l I • • • j . , I I I I I t 2 Pennanent Controls-Show on Drawings □ Show where site refuse and recycled materials will be handled and stored for pickup. See local municipal requirements for sizes and other details of refuse areas. □ If dumpsters or other receptacles are outdoors, show how the designated area will be covered, graded, and paved to prevent run-on and show locations of berms to prevent runoff from the area. Also show how the designated area will be protected from wind dispersal. □ Any drains from dumpsters, compactors, and tallow bin areas must be connected to a grease removal device before discharge to sanitary sewer. 3 Pennanent Controls-List in Table and Narrative □ State how site refuse will be handled and provide supporting detail to what is shown on plans. □ State that signs will be posted on or near dumpsters with the words "Do not dump hazardous materials here" or similar. 4 Operational BMPs-Include in Table and Narrative □ State how the following will be implemented: Provide adequate number of receptacles. Inspect receptacles regularly; repair or replace leaky receptacles. Keep receptacles covered. Prohibit/ prevent dumping of liquid or hazardous wastes. Post "no hazardous materials" signs. Inspect and pick up litter daily and clean up spills immediately. Keep spill control materials available on-site. See Fact Sheet SC-34, ''Waste Handling and Disposal" in the CASQA Storm Water Quality Handbooks at www .casqa.org/resources /bmp-handbooks /municipal-bmp-handbook. I I • I t I i I I I 1 Potential Sources of Runoff Pollutants □ H. Industrial processes. IXI Not Applicable □ I. Outdoor storage of equipment or materials. (See rows J and K for source control measures for vehicle cleaning, repair, and maintenance.) IXI Not Applicable t I I I I I I I t I 2 Permanent Controls-Show on Drawings □ □ □ Show process area. Show any outdoor storage areas, including how materials will be covered. Show how areas will be graded and bermed to prevent run-on or runoff from area and protected from wind dispersal. Storage of non-hazardous liquids must be covered by a roof and/ or drain to the sanitary sewer system, and be contained by berms, dikes, liners, or vaults. □ Storage of hazardous materials and wastes must be in compliance with the local hazardous materials ordinance and a Hazardous Materials Management Plan for the site. I I t I I I t J • • 3 Permanent Controls-List in Table and Narrative □ If industrial processes are to be located onsite, state: "All process activities to be performed indoors. No processes to drain to exterior or to storm drain system." □ Include a detailed description of materials to be stored, storage areas, and structural features to prevent pollutants from entering storm drains. Where appropriate, reference documentation of compliance with the requirements of local Hazardous Materials Programs for: ■ Hazardous Waste Generation ■ Hazardous Materials Release Response and Inventory ■ California Accidental Release Prevention Program ■ Aboveground Storage Tank ■ Uniform Fire Code Article 80 Section 103(b) & (c) 1991 ■ Underground Storage Tank I I I I I I I I 4 Operational BMPs-Include in Table and Narrative Table and Narrative □ See Fact Sheet SC-10, ''Non-Storm Water Discharges" in the CASQA Storm Water Quality Handbooks at https: / /www.casqa.org/resou rces /bmo-handbooks. □ See the Fact Sheets SC-31, "Outdoor Liquid Container Storage" and SC-33, "Outdoor Storage of Raw Materials" in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources/bm p-handbooks/municipal-bmp-handbook. I I • I I I f I I I I I I I I I I t • • I t 1 Potential Sources of Runoff Pollutants □ J. Vehicle and Equipment Cleaning IXI Not Applicable 2 Permanent Controls-Show on Drawings □ Show on drawings as appropriate: (1) Commercial/industrial facilities having vehicle / equipment cleaning needs must either provide a covered, bermed area for washing act1V1t1es or discourage vehicle/ equipment washing by removing hose bibs and installing signs prohibiting such uses. (2) Multi-dwelling complexes must have a paved, bermed, and covered car wash area (unless car washing is prohibited onsite and hoses are provided with an automatic shut-off to discourage such use). (3) Washing areas for cars, vehicles, and equipment must be paved, designed to prevent run-on to or runoff from the area, and plumbed to drain to the sanitary sewer. ( 4) Commercial car wash facilities must be designed such that no runoff from the facility is discharged to the storm drain system. Wastewater from the facility must discharge to the sanitary sewer, or a wastewater reclamation system must be installed. I I ' • t • . , 3 Permanent Controls-List in Table and Narrative □ If a car wash area is not provided, describe measures taken to discourage onsite car washing and explain how these will be enforced. i I I I a I l I 4 Operational BMPs-Include in Table and Narrative Describe operational measures to implement the following (if applicable): □ Washwater from vehicle and equipment washing operations must not be discharged to the storm drain system. □ Car dealerships and similar may rinse cars with water only. □ See Fact Sheet SC-21, ''Vehicle and Equipment Cleaning," in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources/bm p-handbooks/municipal-bmp-handbook. i I i I I a • • I I 1 Potential Sources of Runoff Pollutants □ K. Vehicle/Equipment Repair and Maintenance !Kl Not Applicable I I l I ' . I I • • □ □ □ Permanent Controls-Show on Drawings Accommodate all vehicle equipment repair and maintenance indoors. Or designate an outdoor work area and design the area to protect from rainfall, run-on runoff, and wind dispersal. Show secondary containment for exterior work areas where motor oil, brake fluid, gasoline, diesel fuel, radiator fluid, acid-containing batteries or other hazardous materials or hazardous wastes are used or stored. Drains must not be installed within the secondary containment areas. Add a note on the plans that states either (1) there are no floor drains, or (2) floor drains are connected to wastewater pretreatment systems prior to discharge to the sanitary sewer and an industrial waste discharge permit will be obtained. I I I I • • ' I . , I I I I t I l I Permanent Controls-List in Table and Narrative Operational BMPs-lnclude in Table and Narrative □ State that no vehicle repair or I In the report, note that all of the following maintenance will be done restrictions apply to use the site: □ outdoors, or else describe the I □ required features of the outdoor work area. State that there are no floor drains or if there are floor drains, note the agency from I □ which an industrial waste discharge permit will be obtained and that the design meets that agency's requirements. □ State that there are no tanks, containers or sinks to be used for parts cleaning or rinsing or, if there are, note the I □ agency from which an industrial waste discharge permit will be obtained and that the design meets that agency's requirements. No person must dispose of, nor permit the disposal, directly or indirectly of vehicle fluids, hazardous materials, or rinsewater from parts cleaning into storm drains. No vehicle fluid removal must be performed outside a building, nor on asphalt or ground surfaces, whether inside or outside a building, except in such a manner as to ensure that any spilled fluid will be in an area of secondary containment. Leaking vehicle fluids must be contained or drained from the vehicle immediately. No person must leave unattended drip parts or other open containers containing vehicle fluid, unless such containers are in use or in an area of secondary containment. I I i I I I i I I I I I 1 Potential Sources of Runoff Pollutants I t I t I I I I 2 Permanent Controls-Show on Drawings I I I I l I I j 3 Permanent Controls-List in Table and Narrative □ L. Fuel Dispensing I □ Fueling areas16 must have impermeable floors (i.e., portland cement concrete or equivalent smooth impervious surface) that are (1) graded Areas Ill Not Applicable at the minimum slope necessary to prevent ponding; and (2) separated from the rest of the site by a grade break that prevents run-on of storm water to the MEP. □ Fueling areas must be covered by a canopy that extends a minimum of ten feet in each direction from each pump. [Alternative: The fueling area must be covered and the cover's minimum dimensions must be equal to or greater than the area within the grade break or fuel dispensing area 1.] The canopy [or cover] must not drain onto the fueling area. I I I I I I l I I I 4 Operational BMPs-lnclude in Table and Narrative □ The property owner must dry sweep the fueling area routinely. □ See the Business Guide Sheet, "Automotive Service-Service Stations" in the CASQA Storm Water Quality Handbooks at https: / /www.casqa.org/resources lb mp-handbooks. 16 The fueling area must be defined as the area extending a minimum of 6.5 feet from the comer of each fuel dispenser or the length at which the hose and nozzle assembly may be operated plus a minimum of one foot, whichever is greater. l I I I I l I I I I I I I I I I t I I I I I I I I I I I 1 Potential Sources of Runoff Pollutants M. Loading Docks IXI Not Applicable 2 Permanent Controls-Show on Drawings □ Show a preliminary design for the loading dock area, including roofing and drainage. Loading docks must be covered and/ or graded to minimize run-on to and runoff from the loading area. Roof downspouts must be positioned to direct storm water away from the loading area. Water from loading dock areas should be drained to the sanitary sewer where feasible. Direct connections to storm drains from depressed loading docks are prohibited. □ Loading dock areas draining directly to the sanitary sewer must be equipped with a spill control valve or equivalent device, which must be kept closed during periods of operation. □ Provide a roof overhang over the loading area or install door skirts ( cowling) at each bay that enclose the end of the trailer. 3 Permanent Controls-List in • I l I I I I I I I 4 Operational BMPs-Include in Table and Narrative i I □ Move loaded and unloaded items indoors as soon as possible. □ See Fact Sheet SC-30, "Outdoor Loading and Unloading," in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources /bmp-handbooks /municipal-bmp-handbook. I I i t I I a I I I I I I I t_ I I t I I I I I I I t t I I I I I I I l I l I 1 Potential Sources of Runoff Pollutants □ N. Fire Sprinkler Test Water Iii Not Applicable 0. Miscellaneous Drain or Wash Water □ Boiler drain lines □ Condensate drain lines □ Rooftop equipment □ Drainage sumps □ Roofing, gutters, and trim m Not Applicable 2 Permanent Controls-Show on Drawings 3 4 Permanent Controls-List in Table and Narrative Operational BMPs-Include in Table and Narrative □ Provide a means to drain fire sprinkler test water I □ to the sanitary sewer. □ Boiler drain lines must be directly or indirectly connected to the sanitary sewer system and may not discharge to the storm drain system. □ Condensate drain lines may discharge to landscaped areas if the flow is small enough that runoff will not occur. Condensate drain lines may not discharge to the storm drain system. □ Rooftop mounted equipment with potential to produce pollutants must be roofed and/ or have secondary containment. □ Any drainage sumps onsite must feature a sediment sump to reduce the quantity of sediment in pumped water. □ Avoid roofing, gutters, and trim made of copper or other unprotected metals that may leach into runoff. See the note in Fact Sheet SC-41, "Building and Grounds Maintenance," in the CASQA Storm Water Quality Handbooks at www.casqa.org/resources /bm p-handbooks/municipal-bmp-handbook 1 I l I A I • • I I 1 Potential Sources of Runoff Pollutants IXI P. sidewalks, parking lots. □ Not Applicable Plazas, and I I I I i a I I I I 2 Permanent Controls-Show on Drawings • I • J t I I I 3 Permanent Controls-List in Table and Narrative I I i I I I I I 1 I 4 Operational BMPs-lnclude in Table and Narrative Iii Plazas, sidewalks, and parking lots must be swept regularly to prevent the accumulation of litter and debris. Debris from pressure washing must be collected to prevent entry into the storm drain system. Washwater containing any cleaning agent or degreaser must be collected and discharged to the sanitary sewer and not discharged to a storm drain. I t • --ATTACHMENT 2 • BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES Indicate which Items are Included behind this cover sheet: --Attachment Contents Checklist Sequence Attachment 2a Hydromodification Management IX! Included Exhibit (Required) See Hydromodification Management Exhibit Checklist on the back of this Attachment cover sheet. Attachment 2b Management of Critical Coarse igj Exhibit showing project drainage Sediment Yield Areas (WMAA boundaries marked on WMAA Exhibit is required, additional Critical Coarse Sediment Yield Area analyses are optional) Map (Required) See Section 6.2 of the BMP Design Optional analyses for Critical Manual. Coarse Sediment Yield Area Determination D 6.2.1 Verification of Geomorphic Landscape Units Onsite D 6.2.2 Downstream Systems Sensitivity to Coarse Sediment D 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite Attachment 2c Geomorphic Assessment of IX! Not performed Receiving Channels (Optional) D Included .. See Section 6.3.4 of the BMP Design Manual. .. Attachment 2d Flow Control Facility Design and IX! Included Structural BMP Drawdown Calculations (Required) See Chapter 6 and Appendix G of .. the BMP Design Manual -----42 -- -- • • ------.. -• -------- -------.. -... -- Attachment 2a Hydromodification Management Exhibit 43 -------------·-·. ' . '. \v' .. . 'v L ,. ___ _ ' ' ' \\J . SM 1 7 \!23,568 SFI \\PROPOSED \BROW DI TCH K\Civil 3D\1326\PROD\DWG\HYDRO & SWMP\1326-DMA-HMP EXHIBIT.dwg, 7/18/2017 2:50:44 PM \ !. ,-. ?~/:< ' r : ~ ~~~-~-:~ --.,,ff ---- .1/1 I l,L _H. -+II:__~-'--~ .;"-"'/,'-c-// •: .. PROPOSED CONDITION HYDROMODIFICATION MANAGEMENT EXHIBIT \ -, \ '\' \ .. \ ' \; PRO OS~ ,,,,BRO . \ DITG -' ,,,,_ d, \ / ,., < -~ \.~ \-, ' \ ' \ ' ' ' ' ' ' I I I I I ' f ' ' ! j . ' I ~ AFTON WAY SUBDIVISION, CARLSBAD, CA ' EXIST. . c\) \ c;,· ·, ·' ' - \ !DEWALi< . , NDERDRAIN PP£, ! ; ' ! i \ \ /'<'~ \,, t:~~--~ i ' 1 ' ; __ ..,_J ' I PROJECT CHARACTERISTICS SOIL TYPE PROJECT AR EA DISTURBED AREA PROPOSED IMPER\/OUS AREA PROPOSED PERVIOUS AREA LEGEND OMA DRAINING TO IMP SELF MIT/GA TING OMA POINT OF CONCENTRATION OMA LIMIT FLOW DIRECTION BIOFIL TRA TION BASIN CONCRETE CUL-0£-SAC IMPERVIOUS DRIVEWAY RIP RAP ENERGY DISS/PATER PROPERTY LIN£ BROW DITCH B & D 4,94 ACRES 3,37 ACRES 1.26 ACRES 2,11 ACRES OMA 1 SM 1 POC 1 f+++++I ' ~ . 1 I I ~ SOIL CLASS/FICA TION BOUNDARY -----, ---- >JW 220' ---- HYDROLOGIC UNIT CONTRIBUTION (WATERSHED) WATERSHED HYDROLOGIC HYDROLOGIC DOWNSTREAM AREA SUB-AREA WA TERBODIES 903 CARLSBAD 904.2 (BUENA 904.21 (EL BUENA \/STA CREEK, \/STA CREEK) SAL TO) BUENA VI STA LAGOON IMPAIRED WATER BODIES IMPAIRED CONSTITUENTS OF CONCERN WATERBODY BUEN A \/STA CREEK SEDIMENT TOXICITY, SELENIUM BUENA \/STA INDICATOR BACTERIA, NUTIRIENTS, LAGOON SEDIMENTATION/SILTATION GENERAL NOTES 1. BIOFIL TIRA TION BASINS TO BE USED AS COMBINED POLLUTANT CONTIROL AND FLOW CONTIROL BMP. 2. BIOFIL TRA TION BASINS TO INCLUDE A PERFORATED UNDERDR AIN PIPE WITH A LOW FLOW ORIFICE BELOW THE BOTTOM OF THE GROWING MEDIUM. BIOFIL TRATION BASINS TO INCLUDE AN IMPERMEABLE LINER BELOW THE GRAVEL LAYER TO RESTRICT INFILTIRATION. 3. THE OUTLET STIRUCTURE FOR BASIN 1 AND BASIN 2 HAVE BEEN DESIGNED BASED ON RESULTS FROM THE "TECHNICAL MEMORANDUM: SWMM MODELING FOR HYDROMODI FIC ATION COMPLI AN CE FOR AFTON WAY, CITY OF CARLSBAD, REVI SED JUNE 17, 201 5", PREPARED BY TORY R. WALKER ENGINEER ING. SEE SWQMP FOR COPY OF REPORT. DEEP ROOTED, DENSE, DROUGHT TYPE B BROW DITCH -"'\l PER SDRSD 0 -75 -.___T~ANT PLANTING SUITABLE --........... FOR Wfil__ DRAINED SOIL _ _ \ SLOT ORIFICE TO ALLOW 700 YR PREDEVELOPMENT FLOW 78" ENGINEERED SOIL MIX 7' V2 STORAGE LA YER """' {2"-PEA GRAVEL OVER "'- 10"-3/4" CRUSHED ROCK) 212.5' 6" PERFORATED PVC UNDERDRAIN PIPE PLACE PIPE WITH PERFORATIONS ATTHEINVERT BW 270' IMPERMEABLE LINER THROUGHOUT----/ RESTRICTOR PLATE TO LIMIT FLOW FROM V2 STORAGE AREA, 2.25" DRAIN DOWN HOLE 78" ENGINEERED SOIL MIX PER G.1.5.3.1 OF BMP DESIGN MANUAL ---- STORM DRAIN CASING TW 215' BASIN 1 TYPE G-1 CATCH BASIN WITH GRATED INL ET FOR POST DEVELOPMENT 100YR FLOW 214.25 RIM - "'> BASIN 2 "' ---- 209.25' 207.5'~ EXIST. GROUND ~ TYPE G-1 CATCH BASIN -..______;yr TH GRATED INLET FOR POST D(VEi:.OPMENT IOOYR FLOW ~ 270' -------- "----. o·.\ 2.5' v "----. ==~:::.:,:_+---:::r-SLOT ORIFICE TO ALL0W_ C: 100 YR PREDEVELOPMENT FLOW FLOW FROM V2 STORAGE AREA, I. 00" DRAIN DOWN HOLE / "-:~:~:~---RESTRICTOR PLATE AT END OF ,_., PERF PIPE IN BASIN 2 TO LIM/ T i;2~oijJ.~7~6~fT=f=~~;:::::j 1' v2 STORAGE LAYER IE./E~O~U~T~l)~:;::::J-__:~~===203.07 (2 "-PEA GRAVEL OVER 203 BW IE OUT ournow I0"-3/4" CRUSHED ROCK) 203. 40 -18" HOPE 6" PERFORATED PVC UNDERDRAIN IE IN GUTT.ET PIPE PIPE PLACE PIPE WITH PERFORATIONS 12" HOPE GUTT.ET PIPE ATTHEINVERT FROM RISER/BASIN I IMPERMEABLE LINER THROUGHOUT SECTION· '~-A" BIOFILTRATION BASIN DETAIL NOT TO SCALE SUMMARY OF DEVELOPED DUAL PURPOSE IMP SUMMARY OF BIOFILTRATION BASIN RISER DETAILS BIOFIL TIRA TION BMP AR EA GRAVEL AM ENDED SURFACE LOWER DEPTH, DEP TH ORIFICE IMP (SF) (1) (IN) (2) SOIL (IN) (FT) (3) (IN) (4) BASIN 1 1,805 12 18 12, 30 1.25 BASIN 2 485 12 18 12, 30 1.25 NOTES: (1) AREA OF AMENDED SOIL AREA EQUAL TO AREA OF GRAVEL. (2) GRAVEL DEPTH NEEDED TO COMPLY WITH HYOROMODIFICA TION CONDITIONS . (3) FIRST NUM BER IS THE SURFACE DEPTH OF THE BMP UP TO THE SLOT INVERT. SECOND NUM BER IS THE TOTAL SURFACE DEPTH FROM BOTTO M OF SURFACE POND TO TOP OF POND WALL (4) DIAM ETER OF ORIFICE IN GRAVEL LAYER WITH INVERT AT BOTTOM OF LA YER; TIED WITH HYDROMOD MIN THRESHOLD (10%02). 50' 100' 150' SCALE: 1'' = 50' bJ.iA,lnc. land planning, cMI engineering, surveying 5115 AVENIDA ENCINAS SU ITE "L" CARLSBAD, CA. 92008-4387 (760) 931-8700 HMP SLOT DIMENSIONS SLOT WEIR LENGTH, DETENTION INVERT INVERT BSLOT ELEVATION BASIN H (IN) (IN) (IN) (1) ELEVATION (2) BASIN 1 3 2 4 12 8' @ 1.75' ELE V. BASIN 2 3 24 12 8' @ 1.75' ELE V. NOTES: (1) ALL ELEVATIONS MEASURED FROM TH E BOTTOM OF THE SURFACE BASIN. (2) ASSUMED 3' X 3' BOX RISER WITH INTERNAL 2' X 2' OPENING (8 FEET INTERNAL PERIMETER). PROPOSED CONDITION HYDROMODIFICATION MANAGEMENT EXHIBIT AFTON WAY SUBDIVISION CARLSBAD, CA ... .. -.. -... -... - ---.. -.. --- - -... - -------.. Attachment 2b WMAA Exhibit 44 Legend ~ 'f 2200 Mon Way 0 Yes Attachment 2d Flow Control Facility Design and Structural BMP Drawdown Calculations See ''Technical Memorandum: SWMM Modeling for Hydromodification Compliance of Afton Way, City of Carlsbad, Revised June 17, 2015", prepared by Tory R. Walker Engineering. See ''Technical Memorandum: Determination of Pre-and Post-Developed 100-year Peak Flow, Afton Way, City of Carlsbad, June 17, 2015", prepared by Tory R. Walker Engineering. 45 '--...... -:?-;----.... ....____ TYPE B BROW DITCH PER SDRSD D-75 SLOT ORIFICE TO ALLOW 100 YR PREDEVELOPMENT FLOW 18" ENGINEERED SOIL MIX 1' V2 STORAGE LA YER ---.._ {2"-PEA GRAVEL OVER "-, 10"-J/4" CRUSHED ROCK) 212.5 6" PERFORATED PVC UNDERDRAIN PIPE PLACE PIPE WITH PERFORATIONS DEEP ROOTED, DENSE, DROUGHT --::::::-rQJ.fRANT PLANTING SUITABLE ---....__ FOR---WEbL__DRAINED SOIL \ :TYPE G-1 CATCH BASIN WITH GRATED INLET TW 215' / FOR POST DEVELOPMENT 100YR FLOW ' 214.25 RIM ---.. BASIN 1 EXIST. GROUND TYPE G-1 CATCH BASIN -----.JV/TH GRATED INLET FOR POST Dtrla0f2!!._ENT 100YR FLOW -............. ./2101 _ _L_l, J tY -------~~~OT ORIFICE TOXi.Lmt_ ATTHEINVERT BW210' t•:L;~·jj ['--100 YR PREDEVELOPMENT FLOW IMPERMEABLE LINER THROUGHOUT---_.,/ RESTRICTOR PLATE TO LIMIT FLOW FROM V2 ,,1..,......:.....--RESTRICTOR PLATE AT END OF STORAGE AREA, 2.25" DRAIN DOWN HOLE 18" ENGINEERED SOIL MIX PER G.1.5.3.1 OF BMP DESIGN MANUAL ---6" PERFORATED PVC UNDERDRAIN PIPE PLACE PIPE WITH PERFORATIONS AT THE INVERT 203.40 IE IN 12" HOPE OUTLET PIPE FROM RISER/BASIN 1 IMPERMEABLE LINER THROUGHOUT SECTION· ':4-A" BIOFILTRATION BASIN DETAIL NOT TO SCALE PERF PIPE IN BASIN 2 TO LIMIT FLOW FROM V2 STORAGE AREA, 1.00" DRAIN DOWN HOLE 1' V2 STORAGE LA YER {2"-PEA GRAVEL OVER 10"-J/4" CRUSHED ROCK) 18" HOPE OUTLET PIPE TABLE 1-Summary Of Developed Dual Purpose IMP IMP DIMENSIONS Biofiltration BMPArea111 Gravel Amended Soil Surface Lower Orifice IMP (ft2) Depth121 (in) (in) Depth141 (in) D (in)131 Basin 1 1,805 12 18 12,30 1.25 Basin 2 485 12 18 12,30 1.25 Notes: (1): Area of amended soil equal to area of gravel. (2): Gravel depth needed to comply with hydromodification conditions. (3): Diameter of the orifice in the gravel layer with invert at bottom of layer, tied with HMP min. threshold {10%0i). (4): First number is the surface depth of the BMP up to the slot invert. Second number is the total surface depth from bottom of surface pond to top pond wall. SLOT INVEFO ELEV. HMP Detention Basin Basin 1 Basin 2 B Btof = BOX Ot!v1£t,JSION t l I NOT TO SCALE TABLE 2-Summary Of Biofiltration Basin Riser Details Slot Dimensions Slot Invert Elevationl11 (in) Hs (in) BsLOT (in) 3 24 12 3 24 12 Notes: (1): All elevations measured from the bottom of the surface of the basin. Hs Weir Length, Invert Elevation121 8'@ 1.75' Elev. 8'@ 1.75' Elev. (2): Assumed 3' x 3' box riser with internal 2' x 2' opening (8 feet internal perimeter). 48 ii .RISFH BOX W4// ,, FRENCH DHAIN, - P£RFORA TED PIP[ D D = 6" --LID OR!FiC[ ORIFICE DETAIL NOT TO SCAIF IMP D(in) d (in) 1 6 1.25 2 6 1.25 49 OUTLET 1r SD LINE 81 JNIET 18n ~•--·-1 SD UNE 8 B PLANVIBW -~ 16.59" 2'J" SECI'JON A-A OUll.ET tr SD UN£ 82 A 211.69 TOP wtiR - 275.33 IE IN. .215.1.9 IF OPFNING 215.00 1£ OUT SECI'J.ONB-B MODIFIED TYPEA-4 CLEAN OUT DETAIL NOT ro SCALE 50 .. .. --.. • .. .. - - - - - - - -... --- -... ---.. ATTACHMENT 3 STRUCTURAL BMP MAINTENANCE INFORMATION Indicate which Items are Included behind this cover sheet: Attachment Contents Checklist Sequence Attachment 3a Structural BMP Maintenance [8J Included Thresholds and Actions (Required) See Structural BMP Maintenance Information Checklist on the back of this Attachment cover sheet. Attachment 3b Draft Maintenance Agreement (when [8J Included applicable) D Not Applicable 51 • .. .. .. -- - - - --- ---------.. --- Attachment 3a Structural BMP Maintenance Thresholds and Actions 52 .. • .. • --- -----... - - ----- ------ PRIVATE TREATMENT CONTROL BMP OPERATION AND MAINTENANCE VERIFICATION FORM BIORETENTION FACILITIES, VEGETATED SWALES & HIGHER RATE BIOFILTERS 1. Transcribe the following information from your notification letter and make corrections as necessary: Permit No.: BMP Location: Responsible Party: Phone Number: Email: Responsible Party Address: Number Street Name & Suffix City/Zip D Check here for Address or phone number change 2. Using the Table below, please describe the inspections and maintenance activities that have been conducted during the fiscal year (July 1 -June 30), and date(s) maintenance was performed. Under "Results of Inspection," indicate whether maintenance was required based on each inspection, and if so, what type of maintenance. If maintenance was required, provide the date maintenance was conducted and a description of the maintenance. REFER TO THE BACK OF THIS SHEET FOR MORE INFORMATION DESCRIBING TYPICAL MAINTENANCE INDICATORS AND MAINTENANCE ACTIVITIES. ff no maintenance was required based on the inspection results, state "no maintenance required." Results of Inspection: Date Maintenance Completed and Date Work needed? Description of Maintenance Conducted What To Look For? Inspected (Yes/No} Accumulation of Sediment, Litter, Grease Standing Water Erosion Overgrown Vegetation Poor Vegetation Establishment Structural Damage 3. Attach copies of available supporting documents (photographs, copies of maintenance contracts, and/or maintenance records). 4. Sign the bottom of the form and return to: Signature of Responsible Party County of San Diego Watershed Protection Program Treatment Control BMP Tracking 5201 Ruffin Road, Suite P, MS 0326 San Diego, CA 92123 OR Email: Watersheds@sdcounty.ca.gov Print Name Date .. • .. • • • .. ----.... --------- - ---------- PRIVATE TREATMENT CONTROL BMP OPERATION AND MAINTENANCE VERIFICATION FORM BIORETENTION FACILITIES, VEGETATED SWALES & HIGHER RATE BIOFIL TERS-SIDE 2 This guide sheet provides general indicators for maintenance only and for a wide array of treatment control BMPs. Your developer prepared maintenance plans specifically for your treatment control BMP as an appendix to the Stormwater Management Plan. Also, if you have a manufactured structure, please refer to the manufacturer's maintenance instructions . Biofilters include the following : □ Vegetated Filter Strip/Swale □ Bioswale □ Bioretention Facility □ Planter Boxes □ Manufactered Higher-Flow-Rate Biofilters, such as Tree-Pit-Style Units. Routine maintenance is needed to ensure that flow is unobstructed, that erosion is prevented, and that soils are held together by plant roots and are biologically active. Typical maintenance consists of the following: Bioretention BMPs Inspection and Maintenance Checklist Typical Maintenance Indicators Typical Maintenance Actions Accumulation of sediment (over 2 inches deep or Remove and properly dispose of accumulated materials, covers vegetation), litter, or debris without damage to the vegetation. Confirm that soil is not clogging and that the area drains after a storm event. Till or replace soil as necessarv. Poor vegetation establishment Ensure vegetation is healthy and dense enough to provide filtering and to protect soils from erosion. Replenish mulch as necessary (if less than 3 inches deep), remove fallen leaves and debris, prune large shrubs or trees, and mow turf areas. Overgrown vegetation-woody vegetation not part Mow or trim as appropriate, but not less than the design of design is present and grass excessively tall height of the vegetation (typically 4-6 inches for grass). (greater than 10 inches) Confirm that irrigation is adequate and not excessive and that sprays do not directly enter overflow grates. Replace dead plants and remove noxious and invasive weeds. Erosion due to concentrated irriQation flow Repair/re-seed eroded areas and adjust the irriQation. Erosion due to concentrated stormwater runoff flow Repair/re-seed eroded areas and make appropriate corrective measures such as adding erosion control blankets, adding stone at flow entry points, or re-grading where necessary.Remove obstructions and sediment accumulations so water disperses. Standing water (BMP not draining) . If mosquito Where there is an underdrain, such as in planter boxes larvae are present and persistent, contact the San and manufactured biofilters, check the underdrain piping Diego County Vector Control Program at (858) 694-to make sure it is intact and unobstructed. Abate any 2888. Mosquito larvicides should be applied only potential vectors by filling holes in the ground in and when absolutely necessary and then only by a around the biofilter facility and by insuring that there are licensed individual or contractor. no areas where water stands longer than 96 hours following a storm . Obstructed inlet or outlet structure Clear obstructions. Damage to structural components such as weirs, Repair or replace as applicable. inlet, or outlet structures Before the wet season and after rain events: remove Where cisterns are part of the system sediment and debris from screens and overflow drains and downspouts; ensure pumps are functioning, where applicable; check integrity of mosquito screens; and; check that covers are properly seated and locked. For manufactured high-flow-rate biofilters, see manufacturer's maintenance guidelines - 411 .. 411 .. • • --- ------- - -------... - -- Attachment 3b Draft Maintenance Agreement I. Purpose and Scope This section was prepared based on the Chapter 7 of City of Carlsbad BMP Design Manual The goal is to insure that the Project proponent accepts responsibility for all facilities maintenance, repair, and replacement from the time they are constructed until the ownership and maintenance responsibilities is formally transferred to the new owner. Facilities shall be maintained in perpetuity and comply with the City's self-inspection, reporting, and verification requirements . II. Inspection, Maintenance Log and Self-Verification Forms Fill the forms on the following pages for each BMP using the maintenance schedule here and the inspection-maintenance checklists in Section VII. These forms shall be signed by the responsible party and retained for at least (5) years. Use the DMA Exhibit for the location of BMPs. (Make duplicate copies of these forms and fill out those, not the original ones.) Ill. Updates, Revisions and Errata This maintenance plan is a living document and based on the changes made by maintenance personnel, such as replacement of mechanical equipments, addition maintenance procedure shall be added and maintenance plan shall be kept up to date. Please add the revisions and updates to the maintenance plan to this section if any, these revisions maybe transmitted to the City at any time. However, at a minimum, updates to the maintenance plan must accompany the annual inspection report. IV. Introduction The 2200 Afton Way Project is located in the City of Carlsbad. The project site is divided by east and westbound Carlsbad Village Drive. The subject property located south of Carlsbad Village Drive, known as Parcel 1 for reference, is approximately 4.56 acres and is bordered by Carlsbad Village Drive to the north, and existing residential developments to the east, south, and west. Currently, the property is occupied by one residential structure with two sheds. The subject property located north of Carlsbad Village Drive, Parcel 2, is approximately 0.36 acres and is bordered by Carlsbad Village Drive to the south, Rising Glen Way to the east, and a multi- story apartment complex to the north. Existing land-use is undisturbed natural terrain and proposes to remain undisturbed. For the nature of this report, only Parcel 1 is proposing to be developed. The project site drains to one Point of Compliance (POC), located east of the project site near Carlsbad Village Drive. The project proposes the development of eight (8) residential lots and related drainage features . 53 - • • .. • • -.. - ----------------.. ------- The project also proposes (2) biofiltration basins for storm water treatment and detention. The biofiltration basins will discharge into a proposed storm drain system which will discharge at an existing Type B curb inlet on the south side of Carlsbad Village Drive, also shown as POC-1 on the DMA Exhibit. V. Responsibility for Maintenance A. General Presidio Pebble Creek Carlsbad 8, LLC will enter into a Stormwater Facilities Maintenance Agreement (SWFMA) with the City of Carlsbad to maintain designated facilities herein this section for the Afton Way Project. The SWFMA will serve as the mechanism to ensure that proper inspection and maintenance is done in an efficient and timely manner. Responsible Party Presidio Pebble Creek Carlsbad 8, LLC 301 West 28th Street, Suite A National City, CA 91950 Presidio Pebble Creek Carlsbad 8, LLC will have the direct responsibility for maintenance of Stormwater controls. A Home Owner's Association (HOA) shall be formed, or establish another mechanism to the satisfaction of the City. Funding for the maintenance activities shall be provided by Presidio Pebble Creek Carlsbad 8, LLC, the HOA, or other mechanism to the satisfaction of the City. Whenever the property is sold and whenever designated individual change, immediately the updated contact information must be provided to the City of Carlsbad. B. Staff Training Program Staff training and education program shall be carried out twice a year, once prior to the rainy season (October 1st) and once during the early dry season (April 30th). The inspection and maintenance training program consists of the operation and function of the biofiltration basins. Please refer to the sections VI and VII for fact sheets and checklists. It is the responsibility of Presidio Pebble Creek Carlsbad 8, LLC to convey the maintenance and inspection information to the employees. Maintenance personnel must be qualified to properly maintain stormwater management facilities. Inadequately trained personnel can cause additional problems resulting in additional maintenance costs . 54 -... - .. • .. .. .. -.... -... ----- - ------------ C. Records Presidio Pebble Creek Carlsbad 8, LLC shall retain education, inspection, and maintenance forms and documents for at least five (5) years . D. Safety Keep safety considerations at the forefront of inspection procedures at all times. Likely hazards should be anticipated and avoided. Never enter a confined space (outlet structure, manhole, etc) without proper training or equipment. A confined space should never be entered without at least one additional person present. If a toxic or flammable substance is discovered, leave the immediate area and contact the local Sheriff at 911. Potentially dangerous (e.g., fuel, chemicals, hazardous materials) substances found in the areas must be referred to the local Sheriffs Office immediately for response by the Hazardous Materials Unit. The emergency contact number is 911 . Vertical drops may be encountered in areas located within and around the facility. Avoid walking on top of retaining walls or other structures that have a significant vertical drop. If a vertical drop is identified within the pond that is greater than 48" in height, make the appropriate note/comment on the maintenance inspection form. VI. Summary of Drainage Areas and Stormwater Facilities A. Drainage Areas The proposed development consists of eight residential home pads, driveways, retaining walls, brow ditches, storm drain pipes, and two (2) biofiltration basins. The proposed improvements will disturb 3.37 acres. The proposed drainage pattern will be similar to the existing drainage pattern with some modifications to incorporate the Best Management Practices (BMPs) into the project design to mimic the impacts on storm water runoff and quality. The proposed runoff from the project site is divided into five (5) Drainage Management Areas (DMAs): (1) OMA Draining to a Biofiltration IMP and (4) Self-Mitigating DMAs. One Point of Compliance (POC-1) has been identified the existing Type B curb inlet on the south side of Carlsbad Village Drive, which is the point at which the majority of the proposed site runoff will be discharge to the Carlsbad MS4 system (see Attachment 1 for Drainage Management Area (OMA) Exhibit). Only Basins A through D are being developed and will consider urban runoff flow rates, durations and velocities. The developed Basin A, or OMA 1, will encompass runoff from Lots 1-6, which will be directed to the front of each lot and onto the proposed cul-de-sac. Runoff will then travel via curb and gutter to a proposed Type-B Curb Inlet on the south side of Afton Way. Runoff from Lots 7 and 8 will be directed to the front of each lot and onto the proposed 55 -... .. .. • .. .. • -... --- - --- - --.. ----.. - ---... cul-de-sac, then travel via curb and gutter to a proposed Type-B Curb Inlet on the north side of Afton Way. The proposed curb inlets will connect to a proposed 18"-dia PVC storm drain pipe adjacent to the eastern project boundary. The 18"-dia storm drain pipe will discharge into a modified Type A6 Cleanout (per SDRSD D-09). The cleanout will include (2) orifices to distribute flow. The size of the orifices are a function of the size of each basin divided by the area of the two basins combined. Once flows are routed via the proposed orifices, the flows are then conveyed via storm drain pipes to the receiving biofiltration LID IMPs called Basin 1 and Basin 2 for treatment and detention. Outflows from the basins will be conveyed via 12"- dia storm drain pipe to the existing Type-B Curb Inlet at POC-1 . The majority of the off-site run-on from Basin B will be intercepted by a proposed brow ditch along the southern and eastern project boundary line and directed to a proposed catch basin on the south side of Afton Way. The catch basin will connect to a proposed 18"-dia storm drain system which will connect to the existing 18"-dia storm drain system underneath Afton Way and eventually Carlsbad Village Drive. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating DMA, SM-1, per Chapter 5 Section 5.2.1 of the City of Carlsbad BMP Design Manual (BMP DM). The off-site run-on from Basin C will be intercepted by a proposed brow ditch along the western project boundary line and directed to a proposed catch basin near the congruent property line of Lot 4 and Lot 5. The catch basin will outlet to a proposed 18"-dia PVC storm drain system which will travel under the proposed cul-de-sac and connect to the existing 18"- dia storm drain system underneath Afton Way and eventually Carlsbad Village Drive. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating DMA, SM-2, per the BMP DM. The remaining runoff in Basin D is proposed to be intercepted by the existing brow ditches at the top of cut slopes along the crib wall and directed to the existing sidewalk underdrain pipes at various locations along Carlsbad Village Drive. The runoff will then enter the existing storm drain system underneath Carlsbad Village Drive as historically. The existing slopes will remain undisturbed and will drain directly offsite, therefore being considered a Self-mitigating DMA, SM-3, per the BMP DM. The proposed drainage facility improvements will consist of minor concrete drainage channels, storm drain pipes, curb inlets, and two detention-biofiltration basins. The biofiltration basins proposed for the four main Drainage Basins A - D are designed so that increases in the drainage discharge rate and velocity will be mitigated up to the 100-year runoff. The proposed biofiltration basins will serve to detain the very minor calculated increase in runoff created by the proposed development, and to mitigate any concentration of storm water discharge that might cause erosion. B. Treatment and Flow-Control Facilities All stormwater runoff will be treated by the biofiltration basins. Flows will discharge from the biofiltration cells via a low flow orifice outlet within the gravel layer or a surface slot within the riser structure. The top of the riser will act as a spillway, such that peak flows can be safely 56 .. -.. .. .. • ------... -... --- ----- - -------- discharged to the receiving storm drain system. A perforated under-drain pipe will be located at the bottom of the basins and will connect to the proposed storm drain system. The proposed storm drain system will outlet at the existing Type B curb inlet on Carlsbad Village Drive. See the DMA Exhibit for the location of BMPs. The biofiltration basins are designed to treat and detain runoff. Pollutants are removed as the runoff passes through the soil layer and the underlying layer of gravel or drain rock. A perforated underdrain pipe will convey flow to the proposed storm drain system. Infiltration of the storm water will not be allowed, and the basins will be lined with a 30-mil HOPE impermeable liner. There will be an overflow outlet, which will convey flows that exceed the capacity of the basins. The basins for this Project are sized for pollutant control and hydromodification control, based on the City of Carlsbad BMP Design Manual. VII. Facility Documentation Please see the following pages regarding the BMPs details and maintenance fact sheets. VIII. Maintenance Schedule and Checklist Fill out the Checklists in the following pages for each BMP. The Required Maintenance activities are at the end of this section. At the discretion of the Project proponent, a qualified Stormwater company may be hired to perform the required inspection and maintenance and provide necessary reports. 57 ... .. -Bio Retention Basin Inspection & Maintenance Checklist ... I Property: -Property Owner: .. Date of Inspection: lnspector(s) Name: Address: -Basin Location: DMA# __ Phone: --Type of Inspection □Monthly D pre-wet season OAtter heavy runoff -D End of wet season Oother: ( 1" or greater) --Y=Yes N=No MR=Maintenance Required NA= Not Applicable -Vegetation & Irrigation: -§Vegetation Is dead or diseased Vegetation & Irrigation systems in good condition Overgrown ONeat and orderly in appearance -Required Maintenance: - - -.. Soil: ... OToo deep or too shallow (the distance from the top of mulch to the top of riser pipe shall be 4") -Required Maintenance: --- -.... PaQe1of 3 - -... - -------- ----- - --- -------------- Mulch: §Missing or Patchy in Appearance Depth of mulch layer less than 3-in Areas of Bare earth Required Maintenance: ______________________ _ Sediment, Trash & Debris: □Accumulated sediment, trash,and debris present D Drain time exceeds 4 hours Required Maintenance: ----------------------- Clogs: §Soil too deep or too shallow accumulated sediment, trash and debris Drain time more than 5 days after rainfall Required Maintenance: ______________________ _ Structural Components: Flow to basin Is Impeded inflow pipes or downspouts are cloged/damaged damaged splash/rock blocks Over flow pipe in damaged or cloged Underdrain pipes cloged or damaged Planter is cracked, leaking or falling apart Pa e 2 of3 .. --.. --- - -... --------- - -------------- Required Maintenance: ----------------------- Inspector Signature: _________ _ Date: _______ _ Inspector Signature: _________ _ Date: _______ _ The basin shall be drained within 5 days after each storm event, standing water for more than 5 days will cause mosquito breeding, contact County of San Diego Vector Control Program at (858) 694-2888. ** The Responsible Party shall retail the maintenance/inspection records for a minimum of 5 years from the date of maintenance.The records shall be made available to the County of San Diego for ins action u on re uest at an time. Pa e 3of 3 - ---.. - -... -----... ----- --- -------.. ---- Stormwater Facility Operation and Maintenance Fact Sheet ► BIORETENTION FACILITIES These facilities remove pollutants primarily by filtering runoff slowly through aerobic, biologically active soil. Routine maintenance is needed to ensure that flow is unobstructed, that erosion is prevented, and that soils are held together by plant roots and are biologically active. Typical maintenance consists of the following: ■ Inspect Inlets for channels, exposure of soils, or other evidence of erosion. Clear any obstructions and remove any accumulation of sediment. Examine rock or other material used as a splash pad and replenish if necessary. ■ Inspect outlets for erosion or plugging. ■ Inspect side slopes for evidence of instability or erosion and correct as necessary. ■ Observe the surface of bioretention facility soil for uniform percolation throughout. If portions of the bioretention facility do not drain within 24 hours after the end of a storm, the soil should be tilled and replanted. Remove any debris or accumulations of sediment. ■ Confirm that check dams and flow spreaders are in place and level and that rivulets and channelization are effectively prevented. ■ Examine the vegetation to ensure that it is healthy and dense enough to provide filtering and to protect soils from erosion. Replenish mulch as necessary, remove fallen leaves and debris, prune large shrubs or trees, and mow turf areas. When mowing, remove no more than t/Jheight of grasses. Confirm that irrigation is adequate and not excessive and that sprays do not directly enter overflow grates. Replace dead plants and remove noxious and invasive vegetation. ■ Abate any potential vectors by filling holes in the ground in and around the bioretention facility and by insuring that there are no areas where water stands longer than 48 hours following a storm. If mosquito larvae are present and persistent, contact the San Diego County Vector Control Program for information and advice. Mosquito larvicides should be applied only when absolutely necessary and then only by a licensed individual or contractor. --- ATTACHMENT 4 -City standard Single Sheet BMP (SSBMP) Exhibit - -... --- ----- - ----.. .. - .. .. 58 -- 7T K:\Civil 3D\1326\PROD\DWG\HYDRO & SWMP\1326-DMA-HMP EXHIBIT.dwg, 7/18/2017 2:49:35 PM .\ -/\ 1/ -·~ -··'".\~-\. '\" '· • \ /: -!-.!../ • ' ,\ \ r,_, \ .. 1\) ', \ -· ' ' • " ' ,. '. ('. . ·,. \ ' ' ,i I i ' ' SWMP NO. ~1~6-=26~-- PARTY RESPONSIBLE FOR MAINTENANCE: NAME PRESIDIO PEBBLE CREEK CARLSBAD 8, LLC ADDRESS 301 WEST 28TH STREET SUITE A CONTACT GARY ARNOLD NATIONAL CITY CA 91950 PHONE NO. (619\ 938--0312 PLAN PREPARED BY: NAME RONALD HOLLOWAY COMPANY~B~H~A~l~NC~·------ ADDRESS 5115 AVENIDA ENCINAS SUITE L CARLSBAD. CA 92008 PHONE NO. (760\ 931-8700 BMP NOTES: CERTIFICATION ____ _ 1. THESE BMPS ARE MANDATORY TO BE INSTALLED PER MANUFACTURER'S RECOMMENDATIONS OR THESE PLANS. 2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 3. NO SUBSTITUTIONS TO THE MATERIAL OR TYPES OR PLANTING TYPES WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 4. NO OCCUPANCY WILL BE GRANTED UNTIL THE CITY INSPECTION STAFF HAS INSPECTED THIS PROJECT FOR APPROPRIATE BMP CONSTRUCTION AND INSTALLATION. 5. REFER TO MAINTENANCE AGREEMENT DOCUMENT. 6. SEE PROJECT SWMP FOR ADDITIONAL INFORMATION. BMP BMP ID# BMPTYPE SYMBOL CASQA NO. QUANTITY HYDROMODIFICATION & TREATMENT CONTROL CD BIOFILTRATION + + + + TC-32 --1.fill5_ SF. AREA ♦ ♦ ♦ ♦ ♦ ♦ + + ♦ 0 BIOFILTRATION + + + + TC-32 ~SF. AREA + + + + + + + ♦ + LOW IMPACT DESIGN (L.I.D.) (3_)-@) ROOF DRAIN TO • SD-11 BEA LANDSCAPING SOURCE CONTROL @-@ STENCILS NO DUMPING SD-13 DRAINS TO OCEAN * CHOOSE FROM THE LIST BELOW FOR COMPLETING THE FIELDS IN THE INSPECTIONS & MAINTENANCE FRENQUENCY COLUMNS: ANNUAL SEMI-ANNUALLY QUARTERLY BIMONTHLY MONTHLY AS NEEDED NONE WEEKLY 1 TIME PER YEAR 2 TIMES PER YEAR 3 TIMES PER YEAR 4 TIMES PER YEAR 0 GRAPHIC SCALE 50 1"=50' 100 150 ~~oYESS s, TABLE DRAWING NO. 495-9B 495-9B 495-9B RONALD L. HOLLOWAY NO. 29271 l'JV\\, FC SHEET NO.(S) 3,4 3,4 3,4 - INSPECTION * MAINTENANCE * FREQUENCY FREQUENCY QUARTERLY SEMI-ANNUALLY QUARTERLY SEMI-ANNUALLY ANNUALLY ANNUALLY -.!:'-' l 1-1-=============================================:=====:====~~====~~===:::: I SH1ET I CITY OF CARLSBAD I SH1ETS I l . I :;,__ ___________ -+-------+--+-------+-------< /j >-------------------------+----+----+-----+----1 I i i· I f ,L- /·/ I I // , I l , I DATE INITIAL DA TE INITIAL REVISION DESCRIPTION OTHER APPROVAL CITY APPROVAL ENGINEERING DEPARTMENT SINGLE SHEET BMP SITE PLAN AFTON WAY TM RECORD COPY PROJECT NO. CT 14-06 Qf:"fl-q/n. [p DRAWING NO, INITIAL 'iiATE mm 495-93 .. .. .. - .. - ... ◄ - - - -... - .. - -... ATTACHMENT 5 "Technical Memorandum: SWMM Modeling for Hydromodification Compliance of Afton Way, City of Carlsbad, Revised June 17, 2015': prepared by Tory R. Walker Engineering. "Technical Memorandum: Determination of Pre-and Post-Developed 100-year Peak Flow, Afton Way, City of Carlsbad, June 17, 2015': prepared by Tory R. Walker Engineering . 59 ECHNICAL MEMORANDUM: SWMM Modeling for Hydromodification Compliance of: Afton Way, Carlsbad, CA Prepared for: Presidio Mana Carlsbad 9, LLC April 9, 2015 (Revised June 5, 2015} Prepared by: +~~ 'Tory Walker, PE, CFM, LEED GA . . R.C.E. 45005 • WALKER ENGINEERING IQNS IN WATER RESOURCES - --- .. .. -... -... - - ---------.. .. • • -.. TO: FROM: DATE: RE: TORY R. WALKER ENGINEERING RELIABLE SOLUTIONS IN WATER RESOURCES TECHNICAL MEMORANDUM Presidio Mana Carlsbad 9, LLC Tory Walker, PE, CFM, LEED GA April 9, 2015 (Revised June 5, 2015) Summary of SWMM Modeling for Hydromodification Compliance for Afton Way, Carlsbad, CA. INTRODUCTION This memorandum summarizes the approach used to model the Afton Way project in the City of Carlsbad, CA, using the Environmental Protection Agency (EPA) Storm Water Management Model 5.0 (SWMM). SWMM analyses were prepared for the pre and post-developed conditions at the site in order to determine if the proposed LID biofiltration facilities meet the Hydromodification Management Plan (HMP) requirements from the San Diego Regional Water Quality Control Board (SDRWQCB) as established in the Final HMP Document dated March 2011, prepared by Brown & Caldwell for the County of San Diego Copermittees, which includes the City of Carlsbad. SWMM Model Development The Afton Way project proposes 8 single-family homes with associated landscaping and hardscape improvements on the property at 2200 Afton Way in Carlsbad, CA, which currently consists of an existing residential structure with two sheds, an access road and open space with native grasses and eucalyptus trees on most of the site. Two SWMM simulations were prepared for this study: the first for the pre-development and the second for the post-developed conditions. The project site drains to one Point of Compliance (POC). For both SWMM simulations, flow duration curves were prepared to determine if the proposed HMP facility is sufficient to meet the current HMP requirements. The inputs required to develop SWMM simulations include rainfall, watershed characteristics, and BMP configurations. The Oceanside Gage from the Project Clean Water website was used for this study, since it is the most representative of the project site precipitation due to elevation and proximity to the project site. Evaporation for the site was modeled using average monthly values from the County hourly dataset. The site was modeled with Type B/C and Type D hydrologic soils as determined from the "Geotechnical Investigation, Proposed Afton Way Residential Development, 2200 Afton Way Carlsbad, CA", by Leighton and Associates, Inc. (see Attachment 8). In existing conditions, soils have been assumed to be uncompacted for the pervious area, compacted for the impervious area of the site in the existing conditions, and fully compacted in the post developed conditions. Other SWMM inputs for the subareas are discussed in the attachments to this document and in Reference [1], where the selection of the parameters is explained in detail. WATERSHED, FLOODPLAIN e?STORM WATER MANAGEMENT· RIVER RESTORATION· FLOOD FACILITIES OESICN • SEDIMENT e? EROSION 122 CIVIC CENTER DRIVE, SUITE 206, VISTA CA 92084 • 760-414-9212 • TRWENGINEERINC.COM ... - -... - .. - - - .. -... - .. • .. .. ······TRWE·-··· Presidio Mana Carlsbad 9, LLC Afton Way HMP HMP MODELING DEVELOPED CONDITIONS Storm water runoff from the proposed project site is routed to one POC, located east of the project site near Carlsbad Village Drive. Runoff is drained to two independent onsite receiving biofiltration LID IMPs called Basin 1 and Basin 2. The area that drains to each basin is a function of the size of each basin divided by the area of the two basins combined (See Table 1). Once flows are routed via the proposed LID I MPs, the flows are then conveyed via storm drain to the aforementioned POC. TABLE 1-TRIBUTARY AREAS TO EACH BASIN 1 1,805 79% 2.83 79% 2 485 21% 0.76 21% Total 2,290 100% 3.59 100% (ll This area does not include the area of the biofiltration basin . The two IMPs are responsible for handling hydromodification requirements for the project site. In developed conditions, both Basins 1 and 2 will have a surface depth of 2.5 feet and a riser spillway structure (see dimensions in Tables 2 and 3). Flows will discharge from the biofiltration cells via a low flow orifice outlet within the gravel layer or a surface slot within the riser structures. The top of the riser structures will act as a spillway, such that peak flows can be safely discharged to the receiving storm drain system. Beneath the invert of the basins' lowest surface discharge lies the proposed LID biofiltration portion of the drainage facility. This portion of the basins is comprised of 12 inches of surface storage, an 18-inch layer of amended soil (a highly sandy, organic rich composite with an infiltration capacity of at least 5 inches/hr) and a 12-inch layer of gravel for additional detention and to accommodate the French drain system. These systems will treat storm water and convey flows to a small diameter lower outlet orifice. Once flows have been routed by the outlet structures, flows will then discharge independently from each basin to the receiving POC discharge location . The biofiltration basins were modeled using the biofiltration LID module within SWMM. The biofiltration module can model the underground gravel storage layer, underdrain with an orifice plate, amended soil layer, and a surface storage pond up to the elevation of the invert of the lowest surface discharge opening in the basins' riser structure. Ponding above the invert of the lowest surface discharge opening in the riser structures is modeled as a detention basin: elevation vs area and elevation vs discharge tables are needed by SWMM for Modified Puls routing purposes . It should be noted that detailed outlet structure location and elevations will be shown on the construction plans based on the recommendations of this study . 2 Job# 359-01 ... - - • • - - - - .. - .. • • • • .. .. • ·······TRWE······· Presidio Mana Carlsbad 9, LLC Afton Way HMP BMP MODELING FOR HMP PURPOSES Modeling of HMP IMP Two LID IMP biofiltration basins are proposed for hydromodification conformance for the project site. Basin dimensions are summarized in Table 2 below . TABLE 2-SUMMARY OF DEVELOPED DUAL PURPOSE IMP Basin 1 2.875 1805 12 18 12, 30 1.25 Basin 2 0.773 485 12 18 12, 30 1.25 Notes: (1): Area of amended soil equal to area of gravel. (2): Gravel depth needed to comply with hydromodification conditions. (3): Diameter of the orifice in the gravel layer with invert at bottom of layer, tied with HMP min. threshold (10%0:,). (4): First number is the surface depth of BMP up to the slot invert. Second number is the total surface depth from the bottom of surface pond to top of pond wall. Table 3 provides a summary of the proposed outlet structures' dimensions (a detailed sketch of the riser structure is provided in Attachment 5 of this memo) . TABLE 3-SUMMARY OF BIOFILTRATION BASIN RISER DETAILS 1 3 24 12 8'@ 1.75' Elev. 2 3 24 12 8'@ 1.75' Elev. Notes: (1): All elevations measured from the bottom of the surface of the basin. (2): Assumed 3' x 3' box riser with internal 2' x 2' opening (8 feet internal perimeter) . Drawdown Calculations To ensure compliance with the 72 hour drawdown requirements per Section 6.4.6 of the Final HMP dated March 2011, drawdown calculations are provided in Attachment 4 of this report. The calculated drawdown times for Basin 1 and 2 are 12 hours and 3.7 hours respectively . 3 Job# 359-01 .. ... -.. --.. • -.. -.. - - ---.... - - .. .. .. • -... ·······TRWE······· Presidio Mana Carlsbad 9, LLC Afton Way HMP FLOW DURATION CURVE COMPARISON The Flow Duration Curve {FDC) for the site was compared at the POC by exporting the hourly runoff time series results from SWMM to a spreadsheet. The Qi and 010 were determined with a partial duration statistical analysis of the runoff time series in an Excel spreadsheet using the Cunnane plotting position method (which is the preferred plotting methodology in the HMP Permit). As the SWMM Model includes a statistical analysis based on the Weibull Plotting Position Method, the Weibull Method was also used within the spreadsheet to ensure that the results were similar to those obtained by the SWMM Model. For this project, the low threshold for the range of analysis is 10% of Qi. The range between 10% of Qi and 010 was divided into 100 equal time intervals; the number of hours that each flow rate was exceeded was counted from the hourly series. Additionally, the intermediate peaks with a return period "i" were obtained (Cl; with i=3 to 9). For the purpose of the plot, the values were presented as percentage of time exceeded for each flow rate. FDC comparison at the POC is illustrated in Figures la and lb in both normal and logarithmic scale. Attachment 5 provides a detailed drainage exhibit for the pre-and post-developed condition. As can be seen in Figures la and lb, the FDC for the proposed condition with the HMP IMP is within 110% of the curve for the existing condition in both peak flows and durations for the POC. The additional runoff volume generated from developing the site will be released to the existing point of compliance at a flow rate below the 10% Qi lower threshold for the POC. Additionally, the project will also not increase peak flow rates between the Qi and the 010, as shown in the graphic and also in the peak flow tables in Attachment 1. SUMMARY This study has demonstrated that the proposed HMP I MPs provided for the Afton Way site are sufficient to meet the current HMP criteria if the cross-sectional areas and volumes recommended within this technical memorandum, and the respective low flow orifice, slots and outlet structure are incorporated as specified within the proposed project site . KEY ASSUMPTIONS 1. Soils Type B/C and Type Dare representative of the existing condition site . 4 Job# 359-01 Presidio Mana Carlsbad 9, LLC Afton Way HMP -TRWE- I a Afton Way -Flow Duration Curve 7 ·-·-·-·-·-·-·-·--·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-1-·-·-•-·-·-·-·-·-'-Q,o ·-·-·-·-·-·-·-·-l-.-·-•-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-•-·-·-·-·-·-·-·-·-·-Q, 2.25 1:"" =:~:=:~: ___ :-·-:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=~=t· ·-·-·-·-·~·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-•-~ ·-·-·-·-·-·::1-;·:·,-f-·-·-· ·-·-·-·-·-·-~-;-·-·-·-·-·-·-·-·1 =-=-= 1~-·-Q, .. ' . -·-•O,, . 2.00 1.7S ·-·-·-·-·-·-·-·-·-l..l·"C'"'-•-·-·-·-' 1.50 1.2S I ' -=J=-I-i 1.00 _____ ...;..... ______ --".-----~"-------'---...;.....--..;._---.. .. 0.75 ·-·-·-·-·-·-·-·--·-·-·-·-·-·-·-·-·-·' -.ir-·-·-·-·-·-· ,. t'l:5!C\a ,.~ ... -.--.-.---.---.-.-.--·-·-·-·--.-:.=.----.-, -· . L.-.J ·--·•""' ... .. 0.2S +---------+---+--,-----,--;----------+-----'....._,""".,..._....__-+-, I -0.1~-·-·-·-·~·-·-·-i-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·, ·-·-·-·-·-· •-r-·1e:1<q 0.00 +------------'---'----+-- 0.001 2.50 0.01 -----"'-•-1"1 Afton Way -Flow Duration Curve 0.1 J == ==J ==: ==:== '==,==:==: ==~== ;=====i===== I :1 1.75 -------+----+-----------+---+---+----+----+-, --+-----1 2.25 2.00 ·-·-·-·-·-·-·-·-·-·-·-·-·I·-·- -·-· ·-·-·-·-·-1 ____ 1 ____ , __ 1.00 o.50 O.JQz-·-·-· 1 ·-·-·-·-·-· --- 0.25 -~-·-·-·: ·-· -.--.-_ ...... -_-,_-_..,._-,_-,_-..J-_-,_-,---.--.--.----~--1-·--.- - -·-·-· --·-·-c·-·----·-1-·-·-·-·-·-·-·-·-· ---·-·~·-·-·11.3Qz --- 0.00 +----~----..--~-----..----------, 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 Figure la and lb. Flow Duration Curve Comparison for POC-1 (logarithmic and normal "x" scale) 5 Job# 359-01 - - .. .. .. .. -... - -... --- ------ .. • • .. • • ······TRWE··· Presidio Mana Carlsbad 9, LLC Afton Way HMP REFERENCES [1] -"Review and Analysis of San Diego County Hydromodification Management Plan (HMP): Assumptions, Criteria, Methods, & Modeling Tools -Prepared for the Cities of San Marcos, Oceanside & Vista", May 2012, TRW Engineering . [2] -"Final Hydromodification Management Plan (HMP) prepared for the County of San Diego", March 2011, Brown and Caldwell. [3] -Order R9-2007-001, California Regional Water Quality Control Board San Diego Region (SDRWQCB). [4] -"Handbook of Hydrology", David R. Maidment, Editor in Chief. 1992, McGraw Hill. ATTACHMENTS 1. Ui to Q10 Comparison Tables 2. FDC Plots (log and natural "x" scale) and Flow Duration Table. 3. List of the "n" largest Peaks: Pre-Development and Post-Development Conditions 4. Elevations vs. Discharge & Stage-Storage Curves to be used in SWMM 5. Post Development Maps, Project plan and section sketches 6. SWMM Input Data in Input Format (Existing and Proposed Models) 7. SWMM Screens and Explanation of Significant Variables 8. Geotechnical Report. 9. Summary files from the SWMM Model 6 Job# 359-01 - - -... • .. -.... - - --- --- - - • .. -• ATTACHMENT 1 Q 2 to Q10 Comparison Tables - - -ATTACHMENT 1 .. Qz to Q10 Comparison Table -POC-1 .. • Return Period Existing Condition (cfs) Mitigated Condition (cfs) Reduction, Exist - Mitigated (cfs) .. 2-year 1.569 0.959 0.610 3-year 1.901 1.275 0.627 .. • 4-year 2.040 1.565 0.474 -5-year 2.161 1.804 0.357 6-year 2.201 1.890 0.311 -7-year 2.292 1.961 0.331 - 8-year 2.348 2.109 0.239 --9-year 2.439 2.279 0.160 -10-year 2.605 2.291 0.315 -----.. ... --.. • .. • -.. -- """ - -... --.. .. .. - --- --------- - 11111 ... -----.. ATTACHMENT 2 FDC Plots (log and natural "x" scale) and Flow Duration Table .. ti .. 111 • • ... • - -... --- ---.. - - .. - .. .. -.. .. ATTACHMENT 2 FLOW DURATION CURVE ANALYSIS 1) Flow duration curve shall not exceed the existing conditions by more than 10%, neither in peak flow nor duration. The figures on the following pages illustrate that the flow duration curve in post-development conditions, after the proposed IMPs, is below the existing flow duration curve. The flow duration curve table following the curves shows that if the interval 0.10Q2 -Q10 is divided in 100 sub-intervals, then a) the post development divided by pre-development durations are never larger than 110% (the permit allows up to 110%); and b) there are no more than 10 intervals in the range 101%-110% which would imply an excess over 10% of the length of the curve (the permit allows less than 10% of excesses measured as 101-110%) . Consequently, the design passes the hydromodification test. It is important to note that the flow duration curve can be expressed in the "x" axis as percentage of time, hours per year, total number of hours, or any other similar time variable. As those variables only differ by a multiplying constant, their plot in logarithmic scale is going to look exactly the same, and compliance can be observed regardless of the variable selected. However, in order to satisfy the City of Carlsbad HMP example, % of time exceeded is the variable of choice in the flow duration curve. The selection of a logarithmic scale in lieu of the normal scale is preferred, as differences between the pre-development and post-development curves can be seen more clearly in the entire range of analysis. Both graphics are presented just to prove the difference. In terms of the "y" axis, the peak flow value is the variable of choice. As an additional analysis performed by TRWE, not only the range of analysis is clearly depicted (10% of Oi to Q10) but also all intermediate flows are shown (Oi, Cl], Q.i, Us, OG, Q7, Os and Qg) in order to demonstrate compliance at any range Ox -Ox+1• It must be pointed out that one of the limitations of both the SWMM and SOHM models is that the intermediate analysis is not performed (to obtain Qi from i = 2 to 10). TRWE performed the analysis using the Cunnane Plotting position Method (the preferred method in the HMP permit) from the "n" largest independent peak flows obtained from the continuous time series. The largest "n" peak flows are included in this attachment, as well as the values of Qi with a return period "i", from i=2 to 10. The Cli values are also added into the flow-duration plot . I t:J 2.75 'lio' -·-·-·-2.50 Qg'·--·-·-·-2.25 ~--· ·-·-.la.._. ·--et·-·-----t-·-·-·-·-I 2.00 ~--·-·-·~ ~--·-·-·-1.75 1.50 Oi'·-·-·-·-1.25 1.00 0.75 n c:.ft_• -· -· -· ... 0.50 o.3Qz-. - . -. 0.25 O.lQz-· -· -· 0.00 0.001 -·-·--·-·--·-·--·-·-·--·=-------·-·-..l, ___ .... .... , .. -·-·--·-·-· -·-·-· -·-·-.. Afton Way -Flow Duration Curve -·-· -·-·-· -· -· --. --·-·-·-·-· -·-·-· -·-· -·-·-· -· -· --· --·-·-·-·-· -·-·-· -·-· -·-·-· -· -· --. --·-·-·-·-· -·-·-· -·-· -·-·-· -· -· --. --·-·-·-·-· -·-·-· -·-· -·-·-· -· -·· --. --·-·-·-·-· -·-·-· -·-· -·-·-· -· -· --. --·-·-·-·-· -·-·-· ~--·-·-· -· -· --. --·-·-·-·-· -·-·-· ~ -·-· ·-· -· -· --. --·-·-·-·-· -·-......... ... ~ I ..,a.. __ -·--· -· --·-·-·-·-· -·-·-· \ ' Ir--,... I I\ l ' ' ~ r\...... ' .... ~ ' --------~ ' "'" . p,. ~--·-•·-· -·--·-·-. -..... ~--·-·· ' ' .... .... .... .... .... -·-·-~--· -·-•·-·-. -... -·-·-·-·-·· ~·->,C-,:,..· -·-·-.., ___ -·-... _ ·-. -... -·-·-·-·-·· --·-·-·· 0.01 Percentap of time exceeded f") -·-· ~---· -·--.. -~J I 'I r -·-· --·--·t· r· --·~ -·-· --·--· . -· :~ -·-· --·--·i ··-·· -·-· ~---·t=· ..... --~ -·-· ~---:L:·::· -· I -·-· --. -.,.. -Existing ~ -· --,~ - -Proposed -·-Ox -·-· --·--· --·· -· -q2 ,_ ____ -·-· -·-·-·-n,. n_ ... ~ :--'\" -·-· --·-·-·-o.~2 .... ~ .... "'-... -.... "' .... -·--·-· --. -Iii..-·-0.1 Q2 I 0.1 Afton Way -Flow Duration Curve 2.75 2.50 :J-· --·-· -·-· -·-·· ~--·-... _,_ ·-·-·-·- -·-· -·-· -·-· -·-·· ~--·-•·-·-·-·-·-QlO • 0 C -·--·-· -·-· -·-·· ..... -.. -·-·-·-·-·-·--·--·-· -·-· -·-·--·-·-·-·-·-·-·-Qg J 2.25 ~ -·--·-· -·-· -·-·· -·-·--·-·-·-·-·-·--·--·-· -·-· -·-·· ~--·-·-·-·-·-·-R! -·-· -·-· -·-· ~--·--·-·-·-·-·-·--·--·-· -·-· -·-·-~--·-··-·....J·-·-·-2.00 1.75 1.50 i a 1.25 1.00 0.75 0.50 0.25 Sif -·-· -·-· -·-· -·-·--·-·-·-·-·-·--·--·-· -·-· ~--·--·-·-·-·-·-·-·-at -·-· -·-· -·-· .... --·--·-·-·-·-·-·--·--·-· -·-· -·-·-~--·-·-·-·-·-·-Ot· -·-· -·-· -·-·· .,.., ___ -·-·-·-·-·-·--·--·-· -·-· -·-·-•·-·-·-·-·-·-·-n. ~,4 ~ -·-· -·-· ~--· -·-·--·-·-·-·-·-·--·--·-· i-•-· -·-·--·-·-·-·-·-·-·-Q3 \ ' )I __ I Qz·r -·-· -·-·· .... --·--·-·-·-·-·-·--·--·-· -·-· -·-·-~--·-··-·-·-·-·-Q2 \ '11 I I -Existing ' ~ --Proposed \ ~ -·-0,i . I -~ ' I ' nr:ft·-··-·-~-·--·-· -·-· -·-·· .... --·--·-·-~--·-·-·--·--·-· -·-· -·-·· -~---,............. --.... .... '--'I'-.... .............._ .... 0.3Qi • -·-·-·-·-·-·------:.; :: . -·-·· ~ -·-·-•·-·-·-·--·--·-· -·-· -·-·· -03Q2 ... -----. ----i-,...,.__ ----~ --0.00 0.11:ti -~--·-·-·-·-·--·--·-· -·-· .... --·--·-·-·-·-·-·-=-----~-· --· -·-·· -o:1"Q2 I 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 '-rcemap of time exuedff "') Flow Duration Curve Data for Afton Way, Carlsbad, CA Q2= 1.57 cfs Fraction 10% QlO= 2.61 cfs Step= 0.0247 cfs Count= 499679 hours 57.00 years ::.:1 E)(isting CQhdition ,;, :,i rn¾li:/fa;" Detention Optimized ,0Pass o~ ,, ;{'/''= :'/:· ,,, -·,;-·--:-:-.;,, Jn~erval 1 .Q(cfs) & Hou~,,21,A,. s:r %,iin:,e.,wJ;t ijqy~?Q.1llili;:l!(!Tu ,di1liThllUi"1e i1;1!1i( ,P,ost/f!c~ d\Wt 11i!l@wk f ail?,,,ltii:,. 1 0.157 310 6.20E-02 338 6.76E-02 109% Pass 2 0.182 300 6.00E-02 298 5.96E-02 99% Pass 3 0.206 287 5.74E-02 268 5.36E-02 93% Pass 4 0.231 274 5.48E-02 244 4.88E-02 89% Pass 5 0.256 265 5.30E-02 226 4.52E-02 85% Pass 6 0.281 257 5.14E-02 212 4.24E-02 82% Pass 7 0.305 249 4.98E-02 192 3.84E-02 77% Pass 8 0.330 237 4.74E-02 183 3.66E-02 77% Pass 9 0.355 217 4.34E-02 173 3.46E-02 80% Pass 10 0.379 195 3.90E-02 163 3.26E-02 84% Pass 11 0.404 194 3.88E-02 152 3.04E-02 78% Pass 12 0.429 189 3.78E-02 145 2.90E-02 77% Pass 13 0.454 186 3.72E-02 130 2.60E-02 70% Pass 14 0.478 180 3.60E-02 112 2.24E-02 62% Pass 15 0.503 175 3.50E-02 101 2.02E-02 58% Pass 16 0.528 168 3.36E-02 97 1.94E-02 58% Pass 17 0.553 159 3.18E-02 90 1.80E-02 57% Pass 18 0.577 149 2.98E-02 83 1.66E-02 56% Pass 19 0.602 135 2.70E-02 79 1.58E-02 59% Pass 20 0.627 132 2.64E-02 73 1.46E-02 55% Pass 21 0.652 127 2.54E-02 70 1.40E-02 55% Pass 22 0.676 125 2.S0E-02 64 1.28E-02 51% Pass 23 0.701 116 2.32E-02 57 1.14E-02 49% Pass 24 0.726 108 2.16E-02 56 1.12E-02 52% Pass 25 0.750 104 2.08E-02 54 1.08E-02 52% Pass 26 0.775 100 2.00E-02 51 l.02E-02 51% Pass 27 0.800 97 1.94E-02 48 9.61E-03 49% Pass 28 0.825 95 1.90E-02 46 9.21E-03 48% Pass 29 0.849 92 1.84E-02 43 8.61E-03 47% Pass 30 0.874 89 1.78E-02 40 8.0lE-03 45% Pass 31 0.899 85 1.70E-02 39 7.81E-03 46% Pass 32 0.924 85 1.70E-02 37 7.40E-03 44% Pass 33 0.948 83 1.66E-02 36 7.20E-03 43% Pass 34 0.973 79 1.58E-02 34 6.80E-03 43% Pass 35 0.998 79 1.58E-02 34 6.80E-03 43% Pass 36 1.022 75 1.50E-02 33 6.60E-03 44% Pass 37 1.047 68 1.36E-02 30 6.00E-03 44% Pass 11\l' ,/ Exlstirtg'Coi'lditlonll1~tl¾l11!b %' ,,"@ r>etentt'Sn'opt1mfz.;c1;1i1t'"11:i;wp \J®F~ass or ' Interval Q (cfs) Hours> Q %time Hoilrs'SQ <,%time Post/Pre i½t Fail? 38 1.072 66 1.32E-02 29 5.80E-03 44% Pass 39 1.097 53 1.06E-02 28 5.60E-03 53% Pass 40 1.121 52 1.04E-02 28 5.60E-03 54% Pass 41 1.146 51 1.02E-02 28 5.60E-03 55% Pass 42 1.171 49 9.81E-03 27 5.40E-03 55% Pass 43 1.196 45 9.0lE-03 25 5.00E-03 56% Pass 44 1.220 45 9.0lE-03 25 5.00E-03 56% Pass 45 1.245 45 9.0lE-03 24 4.80E-03 53% Pass 46 1.270 44 8.81E-03 23 4.60E-03 52% Pass 47 1.295 44 8.81E-03 23 4.60E-03 52% Pass 48 1.319 43 8.61E-03 22 4.40E-03 51% Pass 49 1.344 42 8.41E-03 22 4.40E-03 52% Pass so 1.369 42 8.41E-03 22 4.40E-03 52% Pass 51 1.393 42 8.41E-03 22 4.40E-03 52% Pass 52 1.418 39 7.81E-03 22 4.40E-03 56% Pass 53 1.443 37 7.40E-03 22 4.40E-03 59% Pass 54 1.468 34 6.80E-03 21 4.20E-03 62% Pass 55 1.492 34 6.80E-03 20 4.00E-03 59% Pass 56 1.517 34 6.80E-03 18 3.60E-03 53% Pass 57 1.542 34 6.80E-03 18 3.60E-03 53% Pass 58 1.567 33 6.60E-03 17 3.40E-03 52% Pass 59 1.591 32 6.40E-03 16 3.20E-03 50% Pass 60 1.616 32 6.40E-03 16 3.20E-03 50% Pass 61 1.641 32 6.40E-03 16 3.20E-03 50% Pass 62 1.665 32 6.40E-03 16 3.20E-03 50% Pass 63 1.690 31 6.20E-03 16 3.20E-03 52% Pass 64 1.715 30 6.00E-03 15 3.00E-03 50% Pass 65 1.740 29 5.80E-03 14 2.80E-03 48% Pass 66 1.764 28 5.60E-03 14 2.80E-03 50% Pass 67 1.789 28 5.60E-03 14 2.80E-03 50% Pass 68 1.814 26 5.20E-03 13 2.60E-03 50% Pass 69 1.839 23 4.60E-03 12 2.40E-03 52% Pass 70 1.863 23 4.60E-03 12 2.40E-03 52% Pass 71 1.888 22 4.40E-03 11 2.20E-03 50% Pass 72 1.913 22 4.40E-03 11 2.20E-03 50% Pass 73 1.938 21 4.20E-03 11 2.20E-03 52% Pass 74 1.962 21 4.20E-03 10 2.00E-03 48% Pass 75 1.987 20 4.00E-03 10 2.00E-03 50% Pass 76 2.012 20 4.00E-03 9 1.80E-03 45% Pass 77 2.036 17 3.40E-03 9 1.80E-03 53% Pass 78 2.061 17 3.40E-03 9 1.80E-03 53% Pass 79 2.086 16 3.20E-03 9 1.80E-03 56% Pass 80 2.111 15 3.00E-03 9 1.80E-03 60% Pass 81 2.135 15 3.00E-03 9 1.80E-03 60% Pass 82 2.160 14 2.80E-03 9 1.80E-03 64% Pass , th ' IIm'.:'tlii E,tlsi1nl Condltfon:lillf11;ti;,~!W "''i ... ;1)11 Det'entnit,"Optlrrif'zedjJ' ~;-'\twFpass or Interval Q(cfs) Hours>Q %time Hourssc.t 1w '%/".,%time Post/Pre "'Fail? ,, 83 2.185 12 2.40E-03 9 1.80E-03 75% Pass 84 2.210 10 2.00E-03 9 1.80E-03 90% Pass 85 2.234 10 2.00E-03 9 1.80E-03 90% Pass 86 2.259 10 2.00E-03 8 1.60E-03 80% Pass 87 2.284 8 1.60E-03 7 1.40E-03 88% Pass 88 2.309 8 1.60E-03 6 1.20E-03 75% Pass 89 2.333 7 1.40E-03 6 1.20E-03 86% Pass 90 2.358 7 1.40E-03 5 1.00E-03 71% Pass 91 2.383 7 1.40E-03 5 1.00E-03 71% Pass 92 2.407 6 1.20E-03 5 1.00E-03 83% Pass 93 2.432 6 1.20E-03 5 1.00E-03 83% Pass 94 2.457 6 1.20E-03 5 1.00E-03 83% Pass 95 2.482 6 1.20E-03 5 1.00E-03 83% Pass 96 2.506 6 1.20E-03 5 1.00E-03 83% Pass 97 2.531 6 1.20E-03 4 8.0lE-04 67% Pass 98 2.556 6 1.20E-03 4 8.0lE-04 67% Pass 99 2.581 6 1.20E-03 4 8.0lE-04 67% Pass 100 2.605 6 1.20E-03 4 8.0lE-04 67% Pass Peak Flows calculated with Cunnane Plotting Position 10 2.605 2.291 0.315 9 2.439 2.279 0.160 8 2.348 2.109 0.239 7 2.292 1.961 0.331 6 2.201 1.890 0.311 5 2.161 1.804 0.357 4 2.040 1.565 0.474 3 1.901 1.275 0.627 2 1.569 0.959 0.610 • .. • • .. .. .. .. .. • .. .. .. ... ---.. ... -• • ---- ATTACHMENT 3 List of the "n" largest Peaks: Pre-Development and Post-Development Conditions • .. .. 41 .. .. .. .. .. .. - ----- - .. .. .. .. -.. • .. ATTACHMENT 3 List of the "n" Largest Peaks: Pre & Post-Developed Conditions Basic Probabilistic Equation: R = 1/P R: Return period {years). P: Probability of a flow to be equaled or exceeded any given year {dimensionless) . Cunnane Equation: p = i-0.4 n+0.2 Weibull Equation: i P=-n+1 i: Position of the peak whose probability is desired {sorted from large to small) n: number of years analyzed. Explanation of Variables for the Tables in this Attachment Peak: Refers to the peak flow at the date given, taken from the continuous simulation hourly results of then year analyzed. Position: If all peaks are sorted from large to small, the position of the peak in a sorting analysis is included under the variable position. Date: Date of the occurrence of the peak at the outlet from the continuous simulation Note: all peaks are not annual maxima; instead they are defined as event maxima, with a threshold to separate peaks of at least 12 hours. In other words, any peak P in a time series is defined as a value where dP/dt = 0, and the peak is the largest value in 25 hours {12 hours before the hour of occurrence and 12 hours after the occurrence, so it is in essence a daily peak) . - .. - .. • • • .. • .. ---.. ---... - .. ... • - • -• -• List of Peak events and Determination of Q2 and Ql0 (Pre-Development) Afton Way, Carlsbad, CA T Cunnane Weibull Period of Return (Year) (cfs) (cfs) Peaks (cfs) (Years) 10 2.61 2.73 Date Posit Weibull Cunnane 9 2.44 2.52 1.046 11/24/1983 57 1.02 1.01 8 2.35 2.37 1.066 12/10/1965 56 1.04 1.03 7 2.29 2.31 1.073 3/8/1968 55 1.05 1.05 6 2.20 2.22 1.079 3/15/1952 54 1.07 1.07 5 2.16 2.17 1.08 2/23/2005 53 1.09 1.09 4 2.04 2.05 1.084 2/13/1992 52 1.12 1.11 3 1.90 1.91 1.086 9/18/1963 51 1.14 1.13 2 1.57 1.57 1.086 1/11/2005 50 1.16 1.15 1.088 2/18/1980 49 1.18 1.18 1.09 1/15/1978 48 1.21 1.20 Note: 1.091 12/24/1988 47 1.23 1.23 Cunnane is the preferred 1.092 2/4/1994 46 1.26 1.25 method by the HMP permit. 1.122 8/17/1977 45 1.29 1.28 1.15 2/6/1969 44 1.32 1.31 1.163 3/1/1991 43 1.35 1.34 1.178 2/22/1998 42 1.38 1.38 1.178 2/12/2003 41 1.41 1.41 1.179 12/2/1961 40 1.45 1.44 1.18 11/8/2002 39 1.49 1.48 1.251 3/2/1980 38 1.53 1.52 1.312 3/11/1995 37 1.57 1.56 1.336 2/14/1998 36 1.61 1.61 1.422 2/12/1992 35 1.66 1.65 1.422 1/18/1993 34 1.71 1.70 1.449 2/15/1986 33 1.76 1.75 1.457 1/29/1980 32 1.81 1.81 1.464 1/16/1978 31 1.87 1.87 1.565 2/17/1998 30 1.93 1.93 1.569 12/30/1991 29 2.00 2.00 1.679 2/23/1998 28 2.07 2.07 1.724 2/16/1980 27 2.15 2.15 1.756 11/22/1965 26 2.23 2.23 1.809 10/20/2004 25 2.32 2.33 1.811 1/29/1983 24 2.42 2.42 1.814 2/27/1983 23 2.52 2.53 1.828 2/3/1998 22 2.64 2.65 1.829 2/10/1978 21 2.76 2.78 1.872 10/27/2004 20 2.90 2.92 1.928 3/17/1982 19 3.05 3.08 1.971 1/16/1952 18 3.22 3.25 2.012 11/15/1952 17 3.41 3.45 2.019 12/19/1970 16 3.63 3.67 2.027 10/29/2000 15 3.87 3.92 2.071 3/1/1978 14 4.14 4.21 2.1 4/1/1958 13 4.46 4.54 2.157 1/14/1993 12 4.83 4.93 2.185 2/18/2005 11 5.27 5.40 2.197 2/20/1980 10 5.80 5.96 2.271 2/4/1958 9 6.44 6.65 2.323 9/23/1986 8 7.25 7.53 2.383 2/25/1969 7 8.29 8.67 2.641 2/25/2003 6 9.67 10.21 3.162 1/4/1995 5 11.60 12.43 3.29 1/15/1979 4 14.50 15.89 3.624 1/4/1978 3 19.33 22.00 3.636 10/1/1983 2 29.00 35.75 4.021 4/14/2003 1 58.00 95.33 .. - • .. • • • • • ... - -... -... -.. - ... - - • List of Peak events and Determination of Q2 and QlO (Post-Development) Afton Way, Carlsbad, CA T Cunnane Weibull Period of Return (Year) (cfs) (ds) Peaks (cfs) (Years) 10 2.29 2.33 Date Posit Weibull Cunnane 9 2.28 2.28 0.543 2/6/1969 57 1.02 1.01 8 2.11 2.20 0.554 1/29/1957 56 1.04 1.03 7 1.96 1.98 0.57 12/24/1971 55 1.05 1.05 6 1.89 1.90 0.586 1/13/1997 54 1.07 1.07 5 1.80 1.81 0.615 2/17/1998 53 1.09 1.09 4 1.57 1.60 0.615 2/26/2004 52 1.12 1.11 3 1.27 1.28 0.62 2/18/1980 51 1.14 1.13 2 0.96 0.96 0.624 9/23/1986 50 1.16 1.15 0.652 3/1/1991 49 1.18 1.18 0.666 11/22/1996 48 1.21 1.20 Note: 0.666 10/29/2000 47 1.23 1.23 Cunnane is the preferred 0.669 4/1/1958 46 1.26 1.25 method by the HMP permit. 0.693 1/25/1969 45 1.29 1.28 0.727 11/16/1965 44 1.32 1.31 0.737 1/14/1993 43 1.35 1.34 0.768 2/13/1992 42 1.38 1.38 0.771 9/18/1963 41 1.41 1.41 0.772 1/15/1993 40 1.45 1.44 0.778 3/11/1995 39 1.49 1.48 0.798 1/20/1962 38 1.53 1.52 0.82 10/20/2004 37 1.57 1.56 0.827 3/5/1995 36 1.61 1.61 0.833 3/1/1983 35 1.66 1.65 0.84 11/15/1952 34 1.71 1.70 0.867 1/13/1957 33 1.76 1.75 0.875 2/23/2005 32 1.81 1.81 0.92 1/12/1960 31 1.87 1.87 0.921 1/16/1993 30 1.93 1.93 0.959 12/5/1966 29 2.00 2.00 0.964 2/18/2005 28 2.07 2.07 1.004 1/15/1978 27 2.15 2.15 1.025 3/8/1968 26 2.23 2.23 1.03 1/9/2005 25 2.32 2.33 1.062 1/6/1979 24 2.42 2.42 1.18 8/17/1977 23 2.52 2.53 1.185 2/15/1986 22 2.64 2.65 1.234 12/19/1970 21 2.76 2.78 1.248 2/3/1998 20 2.90 2.92 1.299 12/30/1991 19 3.05 3.08 1.462 2/23/1998 18 3.22 3.25 1.474 1/29/1980 17 3.41 3.45 1.506 10/27/2004 16 3.63 3.67 1.51 1/16/1978 15 3.87 3.92 1.703 3/17/1982 14 4.14 4.21 1.733 1/16/1952 13 4.46 4.54 1.8 11/22/1965 12 4.83 4.93 1.826 2/10/1978 11 5.27 5.40 1.887 2/20/1980 10 5.80 5.96 1.941 3/1/1978 9 6.44 6.65 1.991 2/4/1958 8 7.25 7.53 2.275 2/25/1969 7 8.29 8.67 2.293 1/4/1978 6 9.67 10.21 2.521 2/25/2003 5 11.60 12.43 2.947 1/15/1979 4 14.50 15.89 2.949 10/1/1983 3 19.33 22.00 3.303 1/4/1995 2 29.00 35.75 4.161 4/14/2003 1 58.00 95.33 .. • • .. .. --------- - .. - • • ATTACHMENT 4 Elevation vs. Area Curves and Elevation vs. Discharge Curves to be used in SWMM -.. - - .. .. • • • --... ------- .. - • • • -• ATTACHMENT 4 AREA VS ELEVATION The area vs elevation curve in the SWMM model is calculated in Excel and imported into the model. The summary of elevations has been provided on the following page . The LID depth beneath the weir (w/ slots or orifices) is accounted for in the LID module as illustrated in Attachment 7. DISCHARGE VS ELEVATION The orifices have been selected to maximize their size while still restricting flows to conform to the required 10% of the Q2 event flow as mandated in the Final Hydromodification Management Plan by Brown & Caldwell, dated March 2011. While TRWE acknowledges that these orifices are small, to increase the size of these outlets would impact the basin's ability to restrict flows beneath the HMP thresholds, thus preventing the IMP from conformance with HMP requirements. In order to reduce the risk of blockage of the orifices, regular maintenance of the riser and orifices must be performed to ensure potential blockages are minimized. A detail of the orifice and riser structure is provided in Attachment 5 of this memorandum . --- • .. • • • • .. - .. • .. .. -.. • • DISCHARGE EQUATIONS 1) Weir: Qw = Cw · L · H312 (1) 2) Slot: As an orifice: Q5 = B5 • h5 ·cg· jzo (H -:s) (2.a) As a weir: Q5 =Cw• B5 • H312 (2.b) For H > hs slot works as weir until orifice equation provides a smaller discharge. The elevation such that equation (2.a) = equation (2.b) is the elevation at which the behavior changes from weir to orifice. 3) Vertical Orifices As an orifice: Q0 = 0.25 · n:D 2 • Cg • jzg ( H -~) (3.a) As a weir: Critical depth and geometric family of circular sector must be solved to determined Q as a function of H: Q~ A~r -=-; B Tcr Yer = ~ [1 -sin(O.S · «er)] (3.b.1, 3.b.2, 3.b.3, 3.b.4 and 3.b.5) There is a value of H (approximately H = 110% D) from which orifices no longer work as weirs as critical depth is not possible at the entrance of the orifice. This value of H is obtained equaling the discharge using critical equations and equations (3.b) . A mathematical model is prepared with the previous equations depending on the type of discharge. The following are the variables used above: Ow, Os, Oo = Discharge of weir, slot or orifice (ds) Cw, Cg: Coefficients of discharge of weir (typically 3.1) and orifice (0.61 to 0.62) L, B5, D, hs : Length of weir, width of slot, diameter of orifice and height of slot, respectively; (ft) H: Level of water in the pond over the invert of slot, weir or orifice (ft) Aw Tw Ye" ac,: Critical variables for circular sector: area (ft2), top width (ft), critical depth (ft), and angle to the center, respectively . -... -.. -.. .. • .. - • • .. • ... .. - - • -----• - ---- Stage-Area for Basin 1 Elevation (ft) Area (ft2) 0.00 1805 0.08 1809 0.17 1815 0.25 1822 0.33 1828 0.42 1834 0.50 1840 0.58 1847 0.67 1853 0.75 1860 0.83 1866 0.92 1873 1.00 1879 1.08 1886 1.17 1893 1.25 1899 1.33 1906 1.42 1913 1.50 1920 1.58 1926 1.67 1933 1.75 1940 1.83 1947 1.92 1954 2.00 1961 2.08 1969 2.17 1976 2.25 1983 2.33 1990 2.42 1997 2.50 2005 SUB SURFACE STORAGE BASIN BR-80 Elevation (ft) -1.50 -2.50 Gravel & Amended Soil TOTAL = Surface Total TOTAL = IMP TOTAL= Volume (ft3) 0 151 302 453 605 758 911 1065 1219 1373 1529 1684 1841 ~fil~f,t!g!f~ij{2J?•f•·•.·········· 1998 2155 2313 2472 2631 2790 2951 3112 3273 3435 3598 3761 3924 4089 4254 4419 4585 4752 Volume (ft3) 812.3 Amended Soil Base (CU voids) --1-22-.o---ij~~~t•ijaf!l~~4~~~;·•·•••·••·•••1·•··········•·•·······•··• 1534.3 (ft3) 4752.1 (ft3) 6286.4 (ft3) (1): The area at any surface elevation corresponds to the area of gravel and amended soil (Bio-retention layer) (2): Volume at this elevation coresponds with surface volume for WQ purposes (invert of lowest surface outlet) IEffective Depth: 12.24 in ... ---.... --- ---... -.... ----- --- -.. .. -- .. .. - -- Stage-Area for Basin 2 Elevation (ft) Area (ft2) 0.00 485 0.08 495 0.17 504 0.25 513 0.33 522 0.42 532 0.50 541 0.58 551 0.67 560 0.75 569 0.83 579 0.92 589 1.00 598 1.08 608 1.17 617 1.25 627 1.33 637 1.42 647 1.50 657 1.58 666 1.67 676 1.75 686 1.83 696 1.92 706 2.00 716 2.08 727 2.17 737 2.25 747 2.33 757 2.42 767 2.50 778 SUB SURFACE STORAGE BASIN BR-80 Elevation (ft) -1.50 -2.50 Gravel & Amended Soil TOTAL = Surface Total TOTAL = IMP TOTAL= Volume (ft3) 0 41 82 125 168 212 257 302 348 395 443 492 541 suttfj<*i9fll~t~)··•.!•••-•n•• 592 643 694 747 801 855 910 966 1023 1080 1139 1198 1258 1319 1381 1444 1507 1572 Volume (ft) __ 2_1_8_.3_-Amended Soil Base {0,3 voids) i..,__1_94_.o_~~r~v•i~ti'fq~j j~~li .. T·-••-•·· ..... 412.3 (ft3) 1571. 7 (ft3) 1983.9 (ft3) (1): The area at any surface elevation corresponds to the area of gravel and amended soil (Bio-retention layer) (2): Volume at this elevation cores ponds with surface volume for WQ purposes (invert of lowest surface outlet) !Effective Depth: 13.38 in -... -Outlet structure for Discharge of Biofiltration 1 and 2 Discharge vs Elevation Table Low orifice: 1.000" Lower slot Emergency weir: -Number: 0 Invert: 0.00 ft Invert: 0.75 ft Cg-low: 0.62 B 2.00 ft B: 8.00 ft -Middle orifice: 1" h,1ot: 0.250 ft number of orif: 0 Upper slot -Cg-middle: 0.62 Invert: 0.00 ft invert elev: 0.000 ft B: 0.00 ft -h,1ot: 0.000 ft -*Note: All elevations measure 1 feet above the ammended sol!. -h H/D-low H/D-mid Qlow-orlf Qlow-welr Qtot-low Qmld-orlf Qmid-welr Qtot-med Qslot Qslot-upp Qemerg Qtot (ft) --Ids) Ids! (cfs) Ids! Ids! (cfs) (cfs) (cfs) (ds) (cfs) -0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.042 0.500 0.500 0.000 0.000 0.000 0.000 0.000 0.000 0.053 0.000 0.000 0.053 -0.083 1.000 1.000 0.000 0.000 0.000 0.000 0.000 0.000 0.149 0.000 0.000 0.149 0.125 1.500 1.500 0.000 0.000 0.000 0.000 0.000 0.000 0.274 0.000 0.000 0.274 -0.167 2.000 2.000 0.000 0.000 0.000 0.000 0.000 0.000 0.422 0.000 0.000 0.422 0.208 2.500 2.500 0.000 0.000 0.000 0.000 0.000 0.000 0.590 0.000 0.000 0.590 -0.250 3.000 3.000 0.000 0.000 0.000 0.000 0.000 0.000 0.775 0.000 0.000 0.775 0.292 3.500 3.500 0.000 0.000 0.000 0.000 0.000 0.000 0.977 0.000 0.000 0.977 -0.333 4.000 4.000 0.000 0.000 0.000 0.000 0.000 0.000 1.117 0.000 0.000 1.117 0.375 4.500 4.500 0.000 0.000 0.000 0.000 0.000 0.000 1.224 0.000 0.000 1.224 -0.417 5.000 5.000 0.000 0.000 0.000 0.000 0.000 0.000 1.322 0.000 0.000 1.322 0.458 5.500 5.500 0.000 0.000 0.000 0.000 0.000 0.000 1.413 0.000 0.000 1.413 -0.500 6.000 6.000 0.000 0.000 0.000 0.000 0.000 0.000 1.499 0.000 0.000 1.499 0.542 6.500 6.500 0.000 0.000 0.000 0.000 0.000 0.000 1.580 0.000 0.000 1.580 -0.583 7.000 7.000 0.000 0.000 0.000 0.000 0.000 0.000 1.657 0.000 0.000 1.657 0.625 7.500 7.500 0.000 0.000 0.000 0.000 0.000 0.000 1.731 0.000 0.000 1.731 -0.667 8.000 8.000 0.000 0.000 0.000 0.000 0.000 0.000 1.801 0.000 0.000 1.801 0.708 8.500 8.500 0.000 0.000 0.000 0.000 0.000 0.000 1.869 0.000 0.000 1.869 -0.750 9.000 9.000 0.000 0.000 0.000 0.000 0.000 0.000 1.935 0.000 0.000 1.935 0.792 9.500 9.500 0.000 0.000 0.000 0.000 0.000 0.000 1.998 0.000 0.211 2.209 -0.833 10.000 10.000 0.000 0.000 0.000 0.000 0.000 0.000 2.060 0.000 0.597 2.657 0.875 10.500 10.500 0.000 0.000 0.000 0.000 0.000 0.000 2.120 0.000 1.096 3.216 -0.917 11.000 11.000 0.000 0.000 0.000 0.000 0.000 0.000 2.178 0.000 1.687 3.865 0.958 11.500 11.500 0.000 0.000 0.000 0.000 0.000 0.000 2.234 0.000 2.358 4.593 -1.000 12.000 12.000 0.000 0.000 0.000 0.000 0.000 0.000 2.290 0.000 3.100 5.390 1.042 12.500 12.500 0.000 0.000 0.000 0.000 0.000 0.000 2.343 0.000 3.906 6.250 -1.083 13.000 13.000 0.000 0.000 0.000 0.000 0.000 0.000 2.396 0.000 4.773 7.169 1.125 13.500 13.500 0.000 0.000 0.000 0.000 0.000 0.000 2.448 0.000 5.695 8.143 -1.167 14.000 14.000 0.000 0.000 0.000 0.000 0.000 0.000 2.498 0.000 6.670 9.168 1.208 14.500 14.500 0.000 0.000 0.000 0.000 0.000 0.000 2.548 0.000 7.695 10.243 -1.250 15.000 15.000 0.000 0.000 0.000 0.000 0.000 0.000 2.596 0.000 8.768 11.364 1.292 15.500 15.500 0.000 0.000 0.000 0.000 0.000 0.000 2.644 0.000 9.887 12.530 -1.333 16.000 16.000 0.000 0.000 0.000 0.000 0.000 0.000 2.691 0.000 11.049 13.740 1.375 16.500 16.500 0.000 0.000 0.000 0.000 0.000 0.000 2.737 0.000 12.254 14.990 1.417 17.000 17.000 0.000 0.000 0.000 0.000 0.000 0.000 2.782 0.000 13.499 16.281 1.458 17.500 17.500 0.000 0.000 0.000 0.000 0.000 0.000 2.826 0.000 14.785 17.611 -1.500 18.000 18.000 0.000 0.000 0.000 0.000 0.000 0.000 2.870 0.000 16.108 18.978 .. ---- -- -... -... - ---... -.. -.. -------.. --- .. • .. .. .. .. .. .. -- TORY R. WALKER ENGINEERING Project Name ...... . Project No ............ . Afton Way 359-01 6/5/2015 RELIABLE SOLUTIONS IN WATER RESOURCES Date ...................... . Drawdown Calculation for IMP 1 Total Drawdown Time: Underdrain Orifice Diameter: C: Amended Soil Depth: Gravel Depth: Surface Depth (ft) 1.75 1.67 1.58 1.50 1.42 1.33 1.25 1.17 1.08 1.00 0.92 0.83 0.75 0.67 0.58 0.50 0.42 0.33 0.25 0.17 0.08 0.00 12.0 hours 1.25 in 0,61 1.50 ft 1.00 ft Volume (cf) 0..-.(cfs) 3273 0.085 3112 0.085 2951 0.084 2790 0.083 2631 0.082 2472 0.081 2313 0.080 2155 0.079 1998 0.078 1841 0.077 1684 0.077 1529 0.076 1373 0.075 1219 0.074 1065 0.073 911 0.072 758 0.071 605 0.070 453 0.069 302 0.067 151 0.066 0 0.065 Note: Drawdown time is calculated assuming an initial water surface depth equal to the invert of the riser structure. 4T(hr) Total Time (hr) 0.000 0.0 0.527 0.5 0.531 1.1 0.534 1.6 0.538 2.1 0.542 2.7 0.546 3.2 0.550 3.8 0.555 4.3 0.559 4.9 0.564 5.4 0.569 6.0 0.574 6.6 0.580 7.2 0.586 7.8 0.592 8.3 0.598 8.9 0.605 9.5 0.612 10.2 0.619 10.8 0.627 11.4 0.636 12.0 .. - - --- --- --- -... --.. -... -.... .. .. .. .. --.. .. Surface Depth (ft) Volume (cf) Q..r111ce ( cfs) 4T(hr) Total Time (hr) .. .. - TORY R. WALKER ENGINEERING RELIABLE SOLUTIONS IN WATER RESOURCES Project Name ...... . Project No ............ . Date ...................... . Afton Way 359-01 6/5/2015 -Drawdown Calculation for IMP 1 ----,,. --- -... ---------.. • .. - - .. Total Drawdown Time: Underdrain Orifice Diameter: C: Amended Soil Depth: Gravel Depth: Surface Depth (ft} 1.75 1.67 1.58 1.50 1.42 1.33 1.25 1.17 1.08 1.00 0.92 0.83 0.75 0.67 0.58 0.50 0.42 0.33 0.25 0.17 0.08 0.00 3.7 hours 1.25 in 0.61 1.50 ft 1.00 ft Volume (cf) Q.,,lfke (ds) 1023 0.085 966 0.085 910 0.084 855 0.083 801 0.082 747 0.081 694 0.080 643 0.079 592 0.078 541 0.077 492 0.077 443 0.076 395 0.075 348 0.074 302 0.073 257 0.072 212 0.071 168 0.070 125 0.069 82 0.067 41 0.066 0 0.065 Note: Drawdown time is calculated assuming an initial water surface depth equal to the invert of the riser structure. 4T (hr} Total Time (hr) 0.000 0.0 0.185 0.2 0.185 0.4 0.184 0.6 0.183 0.7 0.182 0.9 0.181 1.1 0.181 1.3 0.180 1.5 0.179 1.6 0.178 1.8 0.178 2.0 0.177 2.2 0.176 2.3 0.176 2.5 0.175 2.7 0.175 2.9 0.174 3.0 0.174 3.2 0.173 3.4 0.173 3.6 0.172 3.7 .. - - - .. - - -... - --- - - ---• - -.. -.. -.. ATTACHMENT 5 Vicinity Map, DMA Map, Project Plan and Detention Section Sketches UM., ,S\;MFACl: TAKUI.ATION TO ~til'KII<,. 8Kf-1LTMA'MON Of' 1)1::'SIOI'( ('APll.'ltF. VOLIJ,.lf,trx·v, Of:Tl'.,.ll~A'fl~ 1.2._:: " , .... ~0-.... ,:1 ~--MN1t.,ol-1S-...-.. 11 DRAINAGE MANAGEMENT AREA EXHIBIT AFTON WAY SUBDIVISION, CARLSBAD, CA //1:-~;1{/r:: ,::;--,: ~ ; J f ,' ,,--. . . ,,,,,.,,.,, ... ~ ,, ◊""' ,,.,_,,,y ,,,.,.,-,,-<. "if ✓-f. -I ?, " j ! ~:·:, ...\~~,..,, _,_sr-ORJIORNN ► ~1,. .. CJOsr.i;ow, SroRMf:!!~ ·~ t 1 / r,.··it / : -$ _ -~.,~ s:~· -t~, :~ _ -~t __ r 1, "',:~,,,r,pf, --t '/1L ,.1-,/1 · ,,/\ ; -/"-· · · \. , .. ,...--. , -o1 I ~ ]·I,\ l '""" ..,,~ •· · /J J··-1 1 ; .,>-~ ... .,''~.r_.,.,.t.·--,:,.. ... ,, ~\.---\1'~-•fZ:~·L,'<}l f~.J 1i (" f '.' !~ 1~~ ,,l , .,_ , ' ✓ ~ -¥, ''-, I ' N..... , . --, , , ; ' , ', , • \ -, l 1 ., 1 J I, ,. , , : f' I , ) -,,): '<:~ V / < I ,,,,.., ' ~ f"'I ·---< , , --, , ) \\✓,,.. \ \_ \ ' 1 >1 ' , ,.__.---1 ":-..... I : I ✓ I ....... _l>.,; ' ,//'\~~<~ ">.. \\\~-............ : ;~.1' , "\, ',,, _"#"~ , -: " 4, ',._ '! 5 ,·: .. -. I" .. :~\\ \,,/.->-,\ , ., :✓ Lt,,_;. .... ,, .. ,. ,-l ·, '•-,~:.,-::!OJ { _t PROJECT CHARACTERISTICS PltG..€CT AACA 4.14ACRCS PROP0SCO IMPOf'AOUS AR[A I 1.26 AOl(5 GENERAL NOTES I. 910F'IL'mATION BASINS TO 8£ US£D A5 COM81HCD POLLUTANT CONTROL ANO "-OW CONTitOL 9MPS 2. BK.O.."m.-.TION 8ASINS TO INa..uoE A POl:F'ORATCO UNOOIOR/JN PIPE 'Mll-1 A LOW FLOW ORlfla: BELOW M 80TTOM Of' M CROWING WEOIIJV. 810F11.1'tATION BASINS TO IJICI.UOE AH MP(Rl,l(J.8L£ UNtfl 8ELOW THC CRA'.(l I.A'rOI TO RESTRICT Wk.T'RATl()N, J. 111[ OUTLET Sl!WC1\JR( rOR BASIN 1 ANO BASIN 2 HA\-£ BHH 0ESQE) BASED ON RESlJLTS fl!OM THE "T[QlNICAl. WEMORANDUM S'M,IM MOOEI.JffG FOR H'l'Ol'IOMOOITTCA TlON COMPUANa: FOR AF TOH WAY, CITY Of CAALSflAD, REVISED ..tJN( 17. 2015", PltEPAAED BY TORY R. W-'l.l(ER El'CilNEERING. sa SWOUP FOR COPY or R(P(JRT. SOURCE CONTROL BMPS: LEGEND {JM,I lJR,IJNIN(; 11)/1111' SE.lF l«T1CATINC (JI.IA PCINTorCOK:DITfl/l.00,,, """'' BKnlRATIOiBASM 7::::::l caocrr.a.t.-oc-S4C C5, U'CJNOt/Sll'!l'l{ll'AY ==:J llfPRAPCNCRr.YDISSJPATDl ~ ""°-£CT BWNDA/tY - - - -BROftlDITCH c:, c:> c:> do do SGlaASSflCA'flON """""" SELF-MITIGATING DMAS: VEGETATION ~ THE HATURM. OR l..NfOSCAPC AR[A tS NAn'-'£ OR HOH-NAn~ ~f Ta..£RAl'IT SP[OES. SOILS AR[ UtOSJ\Jff8E0 NATl'YE TOPSOIL. OR OISTURSED SOLS HAYE BEOI MIOIOEO AHO ACJltATEO TO PflOMOTE w.-.ru R(TIJ,JTION CHA.RACTERISTICS [OUIVAU'.HT TO UNOIST\JR8E'DNATl'A'..TIJPSOIL INODENTAL M'(IIVIOUS AREAS ARE LESS Tl-4.AN 5 P£RCEHT Of THE SClF-WtTICAllf\lG ARC.-.. IMPC.VIOUS AREAS CAlOJl.A!!D WITHIN THE S(lF-MITIGAT[D A.REA SH0UU> HOT 8E HYDRAUUCALLY CONNECTED TO OTHER IMPCR...OUS ARC.AS UNL.£SS IT IS A STOftM WA T£R CON'-(YANC( SYST(M (SU04 45 8AOW Ott<M:S}. TH[ SEU'-lillflC.Al'IHC -"'t.A tS HVDRAVUCALLY SEf>'-'lAT[ rROM OMAS il-lAT CONTAIN P(RMAM(t\lT STORM WA.TUI POUUTION CONTROL BMPS. ~tr•'' -~~: /~· OCCP ROOITD. !1CNS£. DINAl(;HT "•:,,rr:,p,.AHTl'f.NirwGSI.ITAIJLE roif'llnl..D!._~~~-1 C.'Tal~ tell>t QWED H.£.T rDR POSroevnOA1£NT roo-,;, n.ow ~ -~ ~ -100 I~ SC.t.LE. ,•.50· bliA.lnc. k'n1P?"::'f,cM•~ ... ~ 51154',t;HIOA[HClt,tA!. SUH[ "L' CARI.S8AO. CA 920Cle.--0&7 (760) 9]1-11700 2'4.2.5 R1'J -. '· mAlL61t'. lfl.O"Uf'NT '(JIIP(A1[,lr£N(J(Y PJ 8,1,SIN 2 IVtlAIII rv,sro,uGCAR!A. 100~/'IOU SfO/lACCL,Otl'I' '.AGl'10tl!MR · atusua, IIOCK} -""" DRAINAGE MANAGEMENT AREA EXHIBIT AFTON WAY SUBDIVISION CARLSBAD, CA ll'\CMlO\lU6WOO',OWG'IM:)IIO,,.S'Nt,!t'\lU..DhU,--l»ff11Tnw,.,,,eno1,u,1:N J"H X 24"W SLOT (SLOT WIDTH CAN BE DISTRIBUTED ON TWO SIDES TO TOTAL 24 ") EXIST. GROUND A1. RISER OUTLET STRUCTURE 18" AMENDED SOIL MIN. INFILTRATION RA TE 5'1/HR. BASIN TOP ELEV (2.50') RISER TOP ELEV (1. 75') BASIN INVERT (0. 00') .______,_ __ BOTTOM OF AMENDED SOIL (-1.50') LID INVERT-BOTTOM OF GRAVEL (-2.50') 1.25-INCH LID ORIFICE {UNDERDRAIN ORIFICE) Bl ORE TENTION AREA BIORETENTION AREA CROSS SECTION NOT TO SCALE IMP H(FT) Hmax (FT) Hg (FT) LID Orifice (IN) Ag (Fr) Abot (Fr) Atop (Fr) 1 1.00 2.50 1.00 1.25 1805 1805 2005 2 1.00 2.50 1.00 1.25 485 485 778 RISER BOX WALL-~ Ll <J RES TRIG TOR PLA TE FRENCH DRAIN __/ D ~LID ORIFICE <J L\ Ll -~ GRAVEL STORAGE LA YER . L\ D = 4" ORIFICE DETAIL NOT TO SCALE SLOT INVERT ELEV I-B ·I I• Bs •1 J_ H Hs T I• Btot = BOX DIMENSION • I OUTLET STRUCTURE DETAIL -SECTION (TYP) NOT TO SCALE OUTLET Bs (FT) SLOT Hs (FT) ELEV (FT) L (FT) 1 2.00 0.25 1.00 8.00 2 2.00 0.25 1.00 8.00 NOTE: L = TOTAL LENGTH OF WEIR {FT). AS RISER IS SQUARE, L=B FT 8s: THIS WIDTH OF THE SLOT CAN BE DISTRIBUTE ON TWO SIDES. WEIR H (FT) 1.75 1.75 ATTACHMENT 6 SWMM Input Data in Input Format (Existing & Proposed Models) [TITLE] [OPTIONS] FLOW UNITS INFILTRATION FLOW ROUTING START DATE START TIME REPORT START DATE --REPORT START TIME --END DATE END TIME SWEEP START SWEEP END DRY DAYS REPORT STEP WET STEP DRY STEP ROUTING STEP ALLOW PONDING INERTIAL DAMPING VARIABLE STEP LENGTHENING STEP MIN SURFAREA NORMAL FLOW LIMITED SKIP STEADY STATE FORCE_MAIN_EQUATION LINK OFFSETS MIN SLOPE [EVAPORATION] CFS GREEN AMPT KINWAVE 10/17/1948 00:00 :00 10/17/1948 00:00 :00 10/17/2005 23:00 :00 01/01 12/31 0 01:00 :00 00 :15:00 04:00:00 0:01:00 NO PARTIAL 0.75 0 0 BOTH NO H-W DEPTH 0 ;;Type Parameters ··--------------------,, PRE-DEVELOPMENT MONTHLY 0 .041 0.076 0.118 0.192 0.237 0 .318 0.308 0 .286 0.217 0.14 DRY ONLY NO [RAINGAGES] ;; Rain Time Snow Data ; ; Name Type Intrvl Catch Source ··--------------------------------- OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE [ SUBCATCHMENT S] Total Pent. Pent . ; ;Name Raingage Outlet Area Imperv Width Slope 0.067 0.041 Curb Snow Length Pack . ·------------------------------------------------------,, Compacted Uncompacted [SUBAREAS] ;;Subcatchment . ·--------------, , Compacted Un compacted [INFILTRATION] ;;Subcatchment ··--------------, , Compacted Uncompacted [LID CONTROLS] -; ; . ·-------------- LID Al LID Al LID Al LID Al LID Al [LID USAGE] - OCEANSIDE POC 0.19 OCEANSIDE POC 3 .45764 N-Imperv N-Perv S-Imperv S-Perv ---------------------------------------- .012 .05 .02 0.1 .012 .05 .02 0 .1 Suction HydCon IMDmax ------------------------------ 6.3 .075 0.31 6.3 .10 0.31 Type/Layer Parameters -------------------- BC SURFACE 16 0 0 SOIL 24 0. 4 0.2 STORAGE 18 0.67 0 .01875 DRAIN 0.1999 0.5 0 1 0 22 12 0 0 402 12 0 PctZero RouteTo PctRouted ------------------------------ 25 OUTLET 25 OUTLET 0 .1 5 0 .1 5 5 1.5 0 6 PRE-DEVELOPMENT ;;Subcatchment LID Process Number Area Width InitSatur Fromimprv ToPerv Report File ··--------------------------------------------------------------------------------------------------,, [OUTFALLS] ;; ; ;Name ··--------------,, Invert Elev. Outfall Type 0 FREE Stage/Table Time Series POC [TIMESERIESJ ; ;Name Date Time Value ··--------------,, OCEANSIDE FILE "OsideRain.prn" [REPORT] INPUT NO CONTROLS NO SUBCATCHMENTS ALL NODES ALL LINKS ALL [TAGS] [MAP] DIMENSIONS 2197.410 5592.134 2215.386 6341.510 Units None [COORDINATES] ; ;Node POC [VERTICES] ; ;Link ··--------------,, [Polygons] ;;Subcatchment Compacted Un compacted [SYMBOLS] ; ;Gage ,;-------------- OCEANSIDE X-Coord 2192.087 X-Coord X-Coord 2281. 812 2079.385 X-Coord 2193.697 Y-Coord 5869 .247 Y-Coord Y-Coord 6023.978 6020.009 Y-Coord 6097.010 Tide Gate NO 2 [TITLE] [OPTIONS] FLOW UNITS CFS INFILTRATION GREEN AMPT FLOW ROUTING KINWAVE START DATE 10/17/1948 START TIME 00:00:00 REPORT START DATE 10/17/1948 REPORT START TIME 00:00:00 --END DATE 10/17/2005 END TIME 23:00:00 SWEEP START 01/01 SWEEP END 12/31 DRY DAYS 0 REPORT STEP 01:00:00 WET STEP 00:15:00 DRY STEP 04:00:00 ROUTING STEP 0:01:00 ALLOW PONDING NO INERTIAL DAMPING PARTIAL VARIABLE STEP 0.75 LENGTHENING STEP 0 MIN SURFAREA 0 NORMAL FLOW LIMITED BOTH SKIP STEADY STATE NO - -FORCE_MAIN_EQUATION H-W LINK OFFSETS DEPTH MIN SLOPE 0 [EVAPORATION] ;;Type Parameters POST-DEVELOPMENT MONTHLY 0.041 0.076 0.118 0.192 0.237 0.318 0.308 0.286 0.217 0.14 0.067 0.041 DRY ONLY NO [RAINGAGES] ; ;Name OCEANSIDE [SUBCATCHMENTS] ;; Snow ; ;Name Pack AREA 1 LID 1 AREA 2 LID 2 [SUBAREAS] ;;Subcatchment . ·--------------'' AREA 1 LID 1 AREA 2 LID 2 [ INFILTRATION] ;;Subcatchment ··--------------'' AREA 1 LID 1 AREA 2 LID 2 [LID_CONTROLS] Rain Time Snow Data Type Intrvl Catch Source ------------------- INTENSITY 1:00 1. 0 TIMESERIES OCEANSIDE Raingage Outlet -------------------------------- OCEANSIDE LID 1 OCEANSIDE DIV 1 OCEANSIDE LID 2 OCEANSIDE DIV 2 N-Imperv N-Perv S-Imperv ------------------------------ 0.012 0.05 0.02 .012 .05 .02 0.012 0.05 0.02 .012 .05 .02 Suction HydCon IMDmax ------------------------------ 6.3 0.075 0.31 6.3 .10 0.31 6.3 0.075 0.31 6.3 .10 0.31 1 Total Area -------- 2.83366 0.041437 0.76140 0.011134 S-Perv ---------- 0 .1 .1 0.1 .1 Pent. Pent. Curb Imperv Widt h Slope Length -------------------------------- 34.7 239 5 0 0 10 1 0 34 .7 64 5 0 0 10 1 0 Pct Zero RouteTo PctRouted 25 25 25 25 OUTLET OUTLET OUTLET OUTLET - ;; Type/Layer Parameters . ·----------------------------------,, BMP 1 BC BMP 1 SURFACE 12.24 BMP 1 SOIL 18 BMP 1 STORAGE 12 BMP 1 DRAIN 0.2882 BMP 2 BC BMP 2 SURFACE 13.38 BMP 2 SOIL 18 BMP 2 STORAGE 12 BMP 2 DRAIN 1. 0727 POST-DEVELOPMENT 0.05 0 0. 4 0.2 0.67 0 0.5 0 .05 0 0.4 0.2 0.67 0 0.5 0 0 0.1 0 6 0 0.1 0 6 5 5 5 5 5 1.5 5 1.5 [LID_USAGE) ;;Subcatchment Report File LID Process Number Area Width InitSatur Fromimprv ToPerv LID 1 LID 2 [OUTFALLS) ; ; ; ; Name ;;-------------- POC [DIVIDERS) , , BMP 1 BMP 2 Invert Elev. ---------- 0 Invert 1 1 Outfall Type ---------- FREE Diverted 1805 485 Stage/Table Time Series 0 0 ---------------- Divider Tide Gate NO 0 0 ; ;Name Elev. Link Type Parameters . ·----------------------------------------, , DIV 1 0 0 DIV 2 0 0 [STORAGE) Invert ;;Name Elev. Infiltration Parameters BASIN 1 0 -BASIN 2 0 - [CONDUITS) ;; Inlet Init. Max. ; ;Name Node Flow Flow BYPASS 1 DIV 1 0 DUM 1 DIV 1 0 BYPASS 2 DIV 2 0 DUM 2 DIV 2 0 [OUTLETS) ;; Flap ; ;Name Qexpon Gate Inlet Node BYPASS BYPASS Max. Depth 1.50 1.50 . ·------------------------------,, 1 2 Init. Depth 0 0 Outlet Node BASIN 1 POC BASIN 2 - POC Outlet Node -------------------- CUTOFF CUTOFF Storage Curve TABULAR TABULAR 0.4102 .04102 Curve Params BR 1 BR 2 Lengt h 10 10 10 10 Outflow Height 0 0 Manning N 0 .01 0.01 0 .01 0.01 Outlet Type 100 100 0 0 Inlet Offset 0 0 0 0 0 0 Ponded Area 1805 485 0 0 Outlet Offset 0 0 0 0 Qcoeff/ QTable OUTLET 1 NO BASIN 1 POC 0 TABULAR/DEPTH Outlet 1 2 Evap. Frac. 1 0 0 0 0 0 OUTLET 2 NO [XSECTIONS] BASIN 2 POC POST-DEVELOPMENT 0 TABULAR/DEPTH Outlet 2 ;;Link Shape Geoml Geom2 Geom3 Geom4 Barrels ··-------------------------------------------------------------- --------------------,, BYPASS 1 DUMMY 0 0 0 0 1 OUM 1 DUMMY 0 0 0 0 1 BYPASS 2 DUMMY 0 0 0 0 1 OUM 2 DUMMY 0 0 0 0 1 [LOSSES] ; ;Link Inlet Outlet Average Flap Gate ··------------------------------------------------------, , [CURVES] ; ;Name Type X-Value Y-Value ··-------------------------------------------- Outlet 1 -Rating 0.000 0.000 Outlet 1 0.042 0.053 -Outlet 1 0.083 0.149 -Outlet 1 0.125 0.274 -Outlet 1 0 .167 0 .422 -Outlet 1 0.208 0.590 -Outlet 1 0.250 0.775 -Outlet 1 0.292 0.977 -Outlet 1 0.333 1.117 -Outlet 1 0.375 1. 224 -Outlet 1 0.417 1 .322 -Outlet 1 0 .458 1. 413 -Outlet 1 0.500 1. 4 99 -Outlet 1 0.542 1. 580 -Outlet 1 0.583 1.657 -Outlet 1 0.625 1.731 Outlet 1 0.667 1. 801 Outlet 1 0.708 1. 869 -Outlet 1 0.750 1.935 -Outlet 1 0.792 2.209 -Outlet 1 0.833 2.657 Outlet 1 0.875 3.216 -Outlet 1 0.917 3 .865 Outlet 1 0.958 4. 593 Outlet 1 1. 000 5.390 -Outlet 1 1. 042 6 .250 Outlet 1 1. 083 7.169 Outlet 1 1.125 8.143 Outlet 1 1.167 9 .168 -Outlet 1 1. 208 10.243 Outlet 1 1. 250 11.364 Outlet 1 1. 292 12.530 Outlet 1 1. 333 13.740 Outlet 1 1. 375 14.990 -Outlet 1 1. 41 7 16.281 Outlet 1 1. 458 17.611 -Outlet 1 1.500 18.978 - Outlet 2 -Rating 0 .000 0.000 Outlet 2 0 .042 0.053 -Outlet 2 0.083 0.149 -Outlet 2 0.125 0.274 -Outlet 2 0.167 0.422 Outlet 2 0.208 0.590 -Outlet 2 0.250 0.775 -Outlet 2 0.292 0.977 -Outlet 2 0.333 1.117 -Outlet 2 0.375 1. 224 -Outlet 2 0.417 1. 322 -Outlet 2 0.458 1. 413 Outlet 2 0 .500 1. 4 99 -Outlet 2 0.542 1. 580 Outlet 2 0.583 1. 657 - 3 POST-DEVELOPMENT Outlet 2 0 .625 1.731 -Outlet 2 0 .667 1. 801 -Outlet 2 0.708 1. 869 -Outlet 2 0.750 1.935 -Outlet 2 0. 792 2.209 -Outlet 2 0.833 2.657 -Outlet 2 0.875 3.216 -Outlet 2 0.917 3.865 -Outlet 2 0.958 4.593 -Outlet 2 1.000 5.390 Outlet 2 1. 042 6.250 -Outlet 2 1.083 7.169 -Outlet 2 1.125 8.143 -Outlet 2 1.167 9 .168 -Outlet 2 1. 208 10.243 -Outlet 2 1.250 11. 364 -Outlet 2 1. 292 12.530 -Outlet 2 1. 333 13.740 -Outlet 2 1. 375 14.990 -Outlet 2 1. 41 7 16.281 -Outlet 2 1.458 17 . 611 -Outlet 2 1. 500 18 .978 - BR 1 Storage 0.00 1879 BR 1 0.08 1886 BR 1 0 .17 1893 BR 1 0.25 1899 BR 1 0.33 1906 BR 1 0.42 1913 BR 1 0.50 1920 BR 1 0.58 1926 BR 1 0.67 1933 -BR 1 0 .75 1940 BR 1 0.83 1947 BR 1 0.92 1954 BR 1 1.00 1961 BR-1 1.08 1969 BR 1 1.17 1976 BR 1 1. 25 1983 BR 1 1. 33 1990 BR 1 1. 42 1997 BR 1 1.50 2005 BR 2 Storage 0.00 598 BR 2 0.08 608 BR 2 0.17 617 BR 2 0.25 627 BR 2 0.33 637 BR 2 0.42 647 BR 2 0.50 657 BR 2 0.58 666 BR 2 0.67 676 BR 2 0.75 686 BR 2 0.83 696 BR 2 0.92 706 BR 2 1.00 716 BR 2 1.08 727 BR-2 1.17 737 BR 2 1. 25 747 BR 2 1.33 757 BR 2 1. 42 767 BR 2 1.50 778 [TIMESERIES] ; ;Name Date Time Value ,,-------------------------------------------- OCEANSIDE FILE "OsideRain.prn" [REPORT] INPUT NO CONTROLS NO 4 POST-DEVELOPMENT SUBCATCHMENTS ALL NODES ALL LINKS ALL [TAGS] [MAP] DIMENSIONS 145.937 4732.028 1987.467 5730 .960 Units None [COORDINATES] ;;Node X-Coord Y-Coord POC 1153.425 4777.434 DIV 1 756.944 5245.370 DIV 2 1445.641 5269.489 BASIN 1 229.643 5244.981 BASIN 2 1903.761 5269.489 [VERTICES) ; ;Link . ·--------------,, [Polygons) ;;Subcatchment ··--------------,, AREA 1 AREA 1 LID 1 AREA 2 LID 2 [SYMBOLS) ; ;Gage . ·--------------,, OCEANSIDE X-Coord X-Coord 751.862 751.862 753.748 1446.285 1445.222 X-Coord 1104.408 Y-Coord Y-Coord 5682 .363 5682.363 5467.442 5685.554 5480.345 Y-Coord 5678. 592 5 ATTACHMENT 7 SWMM Screens and Explanation of Significant Variables ATTACHMENT 7 EPA SWMM FIGURES AND EXPLANATIONS Per the attached, the reader can see the screens associated with the EPA-SWMM Model in both pre-development and post-development conditions. Each portion, i.e., sub-catchments, outfalls, storage units, weir as a discharge, and outfalls (point of compliance), are also shown. Variables for modeling are associated with typical recommended values by the EPA-SWMM model and typical values found in technical literature (such as Maidment's Handbook of Hydrology). Recommended values for the SWMM model have been attained from the interim Orange County criteria established for their SWMM calibration. Currently, no recommended values have been established by the San Diego County HMP Permit for the SWMM Model. Soil characteristics of the existing soils were determined from the site specific Geotechnical Analysis (See Attachment 8). Some values incorporated within the SWMM model have been determined from the professional experience of TRWE using conservative assumptions that have a tendency to increase the size of the needed BMP and also generate a long-term runoff as a percentage of rainfall similar to those measured in gage stations in Southern California by the USGS. r· -Title/Notes -Options •--Climatok>Qy al-· Hydrology i; Eil Hydraulics ! : I""Tf~~· 1 '.··Storage Un ' rt ·· Links : !-·•·Transects ,.. •· I C? @ -e l=·=L=}{'.=W: ___ .f=)l=H:r=•·X=~:,.:..=i=• ==', @ j + -,(;i T ii-~ !i . Outfalls ············-························ Auto-Length: Off • i Offsets: Depth Name X-Coordinate 2192.087 Y-Coordinate 5869.247 Description Tag Inflows NO User-assigned name of outfall Flow Units: CFS • PRE-DEVELOPED CONDITION OCEANSIDE ~ Uncompacted .. Compacted II Zoom Level: 100~ ! X.Y: 2428.408. 6328.234 Name X-Coordinate 2193.697 Y-Coordinate 6097.010 _t Description Tag Rain Format INTENSITY ····"·····--·---------·---1 Time Interval 1:00 j Snow Catch Factor 1.0 f -Station ID -Rain Units IN User-assigned name of rain gage 2079.385 Y-Coordinate 6020.009 Tag Rain Gage OCEANSIDE Outlet POC Area 3.45764 Width 402 % Slope 12 % lmperv 0 N-lmperv .012 .......... , ····'··"· N-Perv .05 D store-I mperv .02 Dstore·Perv 0.1 %Zero-lmperv 25 Subarea Routing OUTLET Percent Routed 100 .......... , ....... Infiltration GREEN_AMPT Groundwater NO Snow Pack LID Controls 0 0 uildup NONE 0 User-assigned name of subcatch X-Coordinate Y-Coordinate escription Tag Rain Gage Outlet Area Width % Slope % lmperv N-lmperv Groundwater Snow Pack LID Controls gth 2281 .812 6023.978 OCEANSIDE POC 0.19 22 12 0.1 25 OUTLET 100 REEN_AMPT NO 0 0 NONE 0 ssigned name of subcatchment Value j63 l: ,. --------1'-"'-"1U-'-'1t,_._.ffM""M'''.._"t",'1JIMlll,.'1tOM,tOMOt,_._ .. ,,, . Conductivity .075 ,-------------------! Initial Deficit I 0.31 Ca.ta [Map ---·~; ~.--T-ile/N'==...,====a l!ig !.1. ; .. Qptions :-. Cimalq O H ~-Hydrology "v {,'_;i_. J1-Hyd,aulc, J:~Quality ◊!\ .-tl' Cu-ves Ej:: :-TimeSeriet ...... f _ Tine Patte,m :. Maplebels + -"' • i ti Tile/Nolet Name X-Coordinate Y-Coordinate Description Tag Inflows Treatment POST-DEVELOPED CONDITION BASlt~_1 BYPASS 1 i::nv_1 -------~---~ Zoornlevet100X X,Y; 1218.115,57:().960 1153.425 4777.434 NO NO X-Coordinate Y-Coordinate Description Tag Rain Format Time Interval AREA 2 Ill - LID 2 Ill - DIV _2 BYPASS 2 1104.408 5678.592 INTENSITY 1:00 1.0 IN er-assigned name of rain gage BASIN_2 t Tag ,,::, Rain Gage CEANSIDE Outlet LID_1 Area 2.83366 Width 239 % Slope 5 % lmperv 34.7 N-lmperv 0.012 N-Perv Dstore·lmperv Dstore-Perv %Zero-lmperv Subarea Routing Percent Routed 100 Infiltration GREEN_AMPT Groundwater NO Snow Pack LID Controls 0 Land Uses Initial Buildup NONE Curb Length 0 User-assigned name of subcatchment • Infiltration Method [ GREEN_AMPT Property Value Suction Head Conductivity 0.075 Initial Deficit 0.31 Description Tag Rain Gage Outlet % Slope % lmperv N-lmperv Percent Routed Infiltration AREA_2 .......... ~ ----_ ..... ., ..... ~~·•---""Fl 1446.285 5685.554 OCEANSIDE LID_2 0.76140 64 5 34.7 0.012 0.05 0.02 0.1 25 OUTLET 100 jGREEN_AMPT .... -----i>- Groundwater NO Snow Pack LID Controls 0 and Uses 0 nitial Buildup NONE urb Length 0 Infiltration parameters (click to edit) · Infiltration Method lGHEE~l .. }.MPT .............................. ,. .... ,~••••--·,. Property Value Suction Head 16. 3 11-----------:, .. , ._,__.,._, ____ .... .._ ..M Conductivity 0.075 Initial Deficit 0 .. 31 % Slope % lmperv 0 N-lmperv .012 N-Perv .05 D store-I mperv .02 '"·------.;.....------N Dstore-Perv .1 %Zero-lmperv Subarea Routing Percent Routed 25 OUTLET 100 4--------';·,,....,...,.,,.,wmwm .. ,mwmw..-w••w.. Infiltration Groundwater Snow Pack LID Controls Land Uses Initial Buildup Curb Length GREEN_AMPT NO Ja NONE 0 Infiltration parameters (click to edit) Infiltration Method [ GREEN_AMPT Property :Value Suction Head 6.3 Conductivity .10 Initial Deficit 0.31 '·"'"-"'""''""'""•"·""·•·"'"''''M"'"''''"''' Y-Coordinate Description Tag in Gage 5480.345 OCEANSIDE DIV_2 0.011134 Width 10 % Slope % lmperv 0 N-lmperv .012 N-Perv .05 .02 .1 %Zero-I mperv 25 Subarea Routing OUTLET ............................ ., ... , .. ,,,. Percent Routed 100 GREEN_AMPT ------,~---·""'-"·'""""'·'"'· NO Snow Pack LID Controls Land Uses 0 ........................................................................... , .... NONE 0 ation parameters (click to edit) Infiltration Method Property Suction Head · Conductivity .10 • initial Deficit 0.31 EXPLANATION OF SELECTED VARIABLES Sub Catchment Areas: Please refer to the attached diagrams that indicate the DMA and Biofiltration IMP {IMP) sub areas modeled within the project site at both the pre and post developed conditions draining to the POC. Parameters for the pre-and post-developed models include soil type B/C (an average of types B and C) and type D as determined from the Geotechnical Analysis (see Attachment 8). Suction head, conductivity and initial deficit corresponds to average values expected for these soils types, according to sources consulted, professional experience, and approximate values obtained by the interim Orange County modeling approach. For this particular project weighted values were used to model the site, as about 60% of the soils are Type B/C and 40% are Type D. Table 1 below shows the breakdown of the Soil types and Table 2 shows the weighted values that were used. TABLE 1-SUMMARY OF SOIL TYPES Areazfypi+, 4 •. ~rellltlifi):i: @., .. ;ki,;J~rea '"'' B/C 96109 60% D 62782 40% Total 158891 100% TABLE 2 -SUMMARY OF GREEN_AMPT VALUES Suction Head Undeveloped Conductivity Developed Conductivity Initial deficit ;:;:. Tyiiee 1 -.;::: ':ix:!'X?t~? 3 0.2 0.15 0.32 6 0.1 0.075 0.31 111 Typical Values used for SWMM modeling. 121 Average of Type Band Type C values. Type0 1 4.5 9 0.15 0.025 0.1125 0.01875 0.315 0.3 Weighted Values Used 6.3 0.100 0.075 0.31 TRWE selected infiltration values, such that the percentage of total precipitation that becomes runoff is realistic for the soil types and slightly smaller than measured values for Southern California watersheds. Selection of a Kinematic Approach: As the continuous model is based on hourly rainfall, and the time of concentration for the pre-development and post-development conditions is significantly smaller than 60 minutes, precise routing of the flows through the impervious surfaces, the underdrain pipe system, and the discharge pipe was considered unnecessary. The truncation error of the precipitation into hourly steps is much more significant than the precise routing in a system where the time of concentration is much smaller than 1 hour. Sub-catchment IMP: The area of each of the bio-filtration must be equal to the area of the development tributary to the bio- filtration facility (area that drains into the bio-filtration, equal external area plus bio-retention itself). Five (5) decimal places were given regarding the areas of the bio-retention to insure that the area used by the program for the LID subroutine corresponds exactly with this tributary. Control Name Number of Replicate Units fEI LID Occupies Full S ubcatchment Area of Each Unit (sq ft or sq m) % of Subcatchment Occupied Top Width of Overland Flow Surface of Each Unit (ft or m) % Initially Saturated % of Impervious Area Treated 1805 100.0 0 0 100 Control Name Number of Replicate Units [J LID Occupies Full Subcatchment Area of Each Unit (sq ft or sq m) % of Subcatchment Occupied Top Width of Overland Flow Surface of Each Unit (ft or m) % Initially Saturated % of Impervious Area Treated 485 100.0 0 0 100 Control Name: LID Type: Process Layers: Surf ace r •. S-oil-.-w 0 -h,.: ,-.5-J?r-.-<!98-. -..... -U_Qt'.t_er_.-'41-.ain-,· Storage Depth 12.24 [in. ormm) Vegetation Volume 0.05 Fraction Surf ace Roughness 0 (Mannings n) Surf ace Slope 0 (percent) LID Type: [ ~io;R~erition Cell Process Layers: i Surface .. SoJy• Storage \,und.ergiain! ==-='------, Height 12 [in. ormm) Void Ratio 0.67 (V aids / Solids) Conductivity 0 (in/hr or mm/hr) Clogging Factor 0 Note: use a Conductivity of 0 if the LID unit has an impermeable bottom. Control Name: LID Type: Stqrage . Underd!ai.n Thickness 18 [in. ormm) Porosity 0.4 [volume fraction) Field Capacity 0.2 ( volume fr action) Wilting Point 0.1 ( volume fr action) Conductivity 5 [in/hr or mm/hr) Conductivity Slope 5 Suction Head 1.5 (in. ormm) Control Name: '@IEill LID Type: Process Layers: ...................................... ;.fa!Yi/AA,. ,,SoiJw•· Sjoi~ Underdrain ~----~ Drain Coelficient [in/hr or mm/hr) Drain Exponent Drain Olfset Height (in. ormm) 0.2882 0.5 0 Note: use a Drain Coefficient of 0 if the LID unit has no underdrain. Control Name: LID Type: Process Layers: !----.--~,.....--~..., Surface Sqi,1t0 ,$torage; J.Jpdetdrain! 5 tor age Depth 13.38 (in. ormm) Vegetation Volume .05 Fraction Surface Roughness 0 (Mannings n) Surface Slope 0 (percent) Control Name: LID Type: Process Layers: ! Surface S.oii;n Stora;~; UnderdraiQ! ~---~----~ Height 12 [in. ormm) Void Ratio 0.67 [\/ aids / Solids) Conductivity 0 (in/hr or mm/hr) Clogging Factor 0 Nate: use a Conductivity of O ii the LID unit has an impermeable bottom. Control Name: LID Type: Process La_yers: :,?UJlj!§g1 Soil Thickness [in. ormm) Porosit_y (volume fraction) Field Capacity [volume fraction) Wilting Point (volume fraction) Conductivit_y [in/hr or mm/hr) Conductivity Slope Suction Head [in. or mm) Control Name: LID Type: Process Layers: Drain Coefficient [in/hr or mm/hr) Drain Exponent Drain Offset Height (in. or mm) 18 0.4 0.2 0.1 5 5 1.5 1.0727 0.5 0 Nate: use a Drain Coefficient of O if the LID unit has no underdrain. LID Control Editor: Explanation of Significant Variables Storage Depth: The storage depth variable within the SWMM model is representative of the storage volume provided beneath the engineered soil and mulch components of the biofiltration facilities. In those cases where the surface storage has a variable area that is also different to the area of the gravel and amended soil, the SWMM model needs to be calibrated as the LID module will use the storage depth multiplied by the IMP area as the amount of volume stored at the surface. Let AiMP be the area of the IMP (area of amended soil and area of gravel). The proper value of the storage depth So to be included in the LID module can be calculated by using geometric properties of the surface volume. Let Ao be the surface area at the bottom of the surface pond, and let Ai be the surface area at the elevation of the invert of the first row of orifices (or at the invert of the riser if not surface orifices are included). Finally, let hi be the difference in elevation between Ao and Ai. By volumetric definition: (1) Equation (1) allows the determination of So to be included as Storage Depth in the LID module. Porosity: A porosity value of 0.4 has been selected for the model. The amended soil is to be highly sandy in content in order to have a saturated hydraulic conductivity of approximately 5 in/hr. TRWE considers such a value to be slightly high; however, in order to comply with the HMP Permit, the value recommended by the Copermittees for the porosity of amended soil is 0.4, per Appendix A of the Final Hydromodification Management Plan by Brown & Caldwell, dated March 2011. Such porosity is equal to the porosity of the gravel per the same document. Void Ratio: The ratio of the void volume divided by the soil volume is directly related to porosity as n/(1-n). As the underdrain layer is composed of gravel, a porosity value of 0.4 has been selected (also per Appendix A of the Final HMP document), which results in a void ratio of 0.4/(1-0.4) = 0.67 for the gravel detention layer. Conductivity: Due to the natural soil and geotechnical conditions existing on site, infiltration is not considered a viable addition to the LID design. Clogging factor: A clogging factor was not used (O indicates that there is not clogging assumed within the model). The reason for this is related to the fairness of a comparison with the SOHM model and the HMP sizing tables: a clogging factor was not considered, and instead, a conservative value of infiltration was recommended. Drain (Flow) coefficient: The flow coefficient in the SWMM Model is the coefficient needed to transform the orifice equation into a general power law equation of the form: (1) where q is the peak flow in in/hr, n is the exponent (typically 0.5 for orifice equation), Ho is the elevation of the centroid of the orifice in inches (assumed equal to the invert of the orifice for small orifices and in our design equal to 0) and H is the depth of the water in inches. The general orifice equation can be expressed as: Q _ rr D2 z (H-Hv) -c -g -4 g 144 12 (2) where Q is the peak flow in cfs, D is the diameter in inches, Cg is the typical discharge coefficient for orifices (0.61-0.63 for thin walls and around 0. 75-0.8 for thick walls), g is the acceleration of gravity in ft/s2, and Hand Ho are defined above and are also used in inches in Equation (2). Detention Basin X-Coordinate 229.643 --··•--·•··-·•-·-••---+-------H Y-Coordinate Description Tag Inflows Treatment nvert El. aK Depth nitial Depth 5244.981 NO 0 0 1.50 0 OUTLET_1 ------.~•·''"·"'"'-"'"-'''"'''''•'''"-"''M'''•'•"''M''' BASIN_1 POC Curve Name BR_1 Description Depth (ft) 1 0.00 ,.,,..,,,,., .. ., .... ,,. .. .,,,.,,,... 2 0.08 -·····---·· 3 0.17 4 0.25 5 0.33 6 0.42 7 0.50 8 0.58 9 0.67 Curve Name Description Head (ft) 1 0.000 2 0.042 3 0.083 4 0.125 5 0.167 6 0.208 7 0.250 -··· ......... ....... _. ....... _,._,. 8 0.292 _ ... ., ·········· ...... 9 0.333 Area ,,. (ft2) [j 1879 .wtt·,·,,·,,,,,·,,, •••»•»·nn,»»» .-.. , 1886 '""·-· 1893 1899 ; ~ 1906 191 3 1920 1926 1933 ' .., J Outflow A (CFS) [j 0.000 0.053 0.149 0.274 0.422 i 0.590 0.775 0.977 1.117 "' Description Tag flows reatment Invert El. 0 Max. Depth 1.50 Initial Depth 0 Ponded Area E vap. Factor ser-assigned name of storage unit Inlet Node BASIN_2 Outlet Node POC ···········••>•········ Description Tag Inlet Offset 0 Flap Gate NO User-assigned name of outlet Curve Name BR_2 Description Depth (ft) Area (ft2) 1---+------,f--------! l 598 0.00 0.08 0.17 0.25 0.33 ' 608 617 ... _. ... _. .. ) ' ..... ···························t 627 637 ::·••;;··················1 0.58 666 0.67 Curve Name Outlet_2 Description Head (ft) 1 0.000 -, .. ,.. ... ,.. .. ,,. .. ,,,..,,,,. .. .,,. .. ., 2 0.042 3 0.083 4 0.125 ,m .. •••• ·······"····. 5 0.167 ~----"•-'W.••··· 6 0.208 -··-·····--=-----· 7 0.250 8 0.292 9 0.333 676 Outflow (CFS) 0.000 0.053 0.149 0.274 0.422 0.590 0.775 0.977 1.117 □ A □ . .... Note: The complete storage and rating curves and the respective explanation is shown at the end of Attachment 4. A variable area vs. elevation storage curve was used for the final model, and a discharge that is a function of the outlet structure in the surface was used also. ATTACHMENT 8 Geotechnical Report • .. • • - .. • • .. -- .. -- .. .. - -.. - GEOTECHNICAL INVESTIGATION, PROPOSED AFTON WAY RESIDENTIAL DEVELOPMENT 2200 AFTON WAY, CARLSBAD, CALIFORNIA Prepared for: PRESIDO MANA CARLSBAD 9, LLC 5927 Balfour Court Carlsbad, California 92008 Project No. 10690.002 September 29, 2014 ----Leighton and Associates 1 Inc. ----- A LEIGHTON GROUP COMPANY • .. • • • • -• .. .. .. -- - -... - -... .. .. .. .. ... .. - - Leighton and Associatesj Inc . A LEIGHTON GROUP COMPANY Presido Mana Carlsbad 9, LLC 5927 Balfour Court Carlsbad, California 92008 Attention: Mr. Orville Power September 29, 2014 Subject: Geotechnical Investigation Proposed Afton Way Residential Development, Project No. 10690.002 2200 Afton Way, Carlsbad, San Diego County, California In accordance with your request and authorization, we have conducted a geotechnical investigation of the property for the design and construction of the proposed residential development project. Based on the results of our study, it is our professional opinion that the site is suitable to receive the proposed improvements. The accompanying report presents a summary of our current investigation and provides geotechnical conclusions and recommendations relative to the proposed site development. 3934 Murphy Canyon Road, Suite B205 ■ San Diego, CA 92123-4425 858.292.8030 ■ Fax 858.292.0771 ■ www.leightongroup.com .. • • C • • • .. -... - -.. - --- 11 .. .. • .. If you have any questions regarding our report, please do not hesitate to contact this office. We appreciate this opportunity to be of service . Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. n;iebv-- Mike Jensen, CEG 2457 Project Geologist ,v.:IL. I.J.cf),L ____ _ William D. Olson, RCE 45283 Associate Engineer /~E=~~/Jf F_ ll~---•~' ~-,-// Bryan Voss, PG 8709 Project Geologist Distribution: (3) Addressee Leighton 11 .. .. • .. • .. .. • .. .. • ----... -... - -... • .. .. .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 TABLE OF CONTENTS Section Page 1.0 INTRODUCTION .............................................................................................. 1 1.1 PURPOSE AND SCOPE ............................. ········· .... ······ ................... ················ .......... 1 1.2 SITE LOCATION AND DESCRIPTION ............................................................................ 1 1.3 PROPOSED DEVELOPMENT ........... ··········· ................................................................ 2 2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING ......... 3 2.1 SITE INVESTIGATION································································································ 3 2.2 LABORATORY TESTING···························································································· 3 3.0 SUMMARY OF GEOTECHNICAL CONDITIONS ...................................... 4 3. 1 GEOLOGIC SETTING ................................................................................................ 4 3.2 SITE-SPECIFIC GEOLOGY ................... ······ .......... ········ ............................................. 4 3.2.1 Artificial Fill -Undocumented -(Afu) ............................................................. 4 3.2.2 Colluvium (Qc) ............................................................................................... 5 3.2.3 Slope Wash Deposits (Qsw) .......................................................................... 5 3.2.4 Very Old Paralic Deposits (Qvop) .................................................................. 5 3.2.5 Santiago Formation {Tsa) .............................................................................. 6 3.3 SURFACE AND GROUND WATER··············································································· 6 3.4 ENGINEERING CHARACTERISTICS OF ON-SITE SOILS .................................................. 6 3.4.1 Expansion Potential ....................................................................................... 7 3.4.2 Compressible Soils ........................................................................................ 7 3.4.3 Soil Corrosivity .............................................................................................. 7 3.4.4 Infiltration ....................................................................................................... 7 3.4.5 Excavation Characteristics ............................................................................ 8 3.5 SLOPE STABILITY···································································································· 8 3.6 EARTHWORK SHRINKAGE AND BULKING .................................................................... 9 4.0 SEISMIC AND GEOLOGIC HAZARDS ..................................................... 10 4.1 REGIONAL TECTONIC SETTING ............................................................................... 10 4.2 LOCAL FAUL TING ·································································································· 10 4.3 SEISMICITY ................. ········ ............................. ·········· ........................................... 10 4.4 SEISMIC HAZARDS ........ ····· ......................... ········· ········· ·············· .......................... 10 4.4.1 Shallow Ground Rupture ............................................................................. 11 4.4.2 Mapped Fault Zones ................................................................................... 11 4.4.3 Site Class .................................................................................................... 11 4.4.4 Building Code Mapped Spectral Acceleration Parameters .......................... 11 4.5 SECONDARY SEISMIC HAZARDS ............................................................................. 12 4.5.1 Liquefaction and Dynamic Settlement ......................................................... 12 4.5.2 Lateral Spread ............................................................................................. 13 4.5.3 Tsunamis and Seiches ................................................................................ 13 Leighton .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 - TABLE OF CONTENTS (Continued} • Section • • 4.6 LANDSLIDES ......................................................................................................... 13 4. 7 FLOOD HAZARD .................................................................................................... 14 .. 5.0 CONCLUSIONS .............................................................................................. 15 6.0 RECOMMENDATIONS .................................................................................. 17 -6.1 EARTHWORK ........................................................................................................ 17 6.1.1 Site Preparation ........................................................................................... 17 6.1.2 Removal of Compressible Soils ................................................................... 17 • 6.1.3 Cut/Fill Transition Mitigation ........................................................................ 18 • 6.1.4 Excavations and Oversize Material ............................................................. 18 6.1.5 Engineered Fill ............................................................................................ 19 .. 6.1.6 Import Soils ................................................................................................. 20 .. 6.1.7 Expansive Soils and Selective Grading ....................................................... 20 6.1.8 Buttress/Replacement Fill. ........................................................................... 20 6.2 FOUNDATION AND SLAB CONSIDERATIONS .............................................................. 21 6.2.1 Conventional Foundations ........................................................................... 21 ... 6.2.2 Foundation Setback .................................................................................... 23 -6.2.3 Settlement ................................................................................................... 24 6.2.4 Moisture Conditioning .................................................................................. 25 -6.2.5 Post-Tension Foundation Recommendations .............................................. 26 -6.3 LATERAL EARTH PRESSURES AND RETAINING WALL DESIGN .................................... 27 6.4 GEOCHEMICAL CONSIDERATIONS ........................................................................... 29 ... 6.5 CONCRETE FLATWORK .......................................................................................... 29 -6.6 PRELIMINARY PAVEMENT DESIGN ........................................................................... 29 6.7 CONTROL OF GROUND WATER AND SURFACE WATERS ............................................ 31 6.8 CONSTRUCTION OBSERVATION .............................................................................. 32 -6.9 PLAN REVIEW ....................................................................................................... 32 7 . 0 LI M IT AT I O NS ................................................................................................. 33 - -----... -ii ... -Leighton .. .. .. • .. • .. .. ... - .. -.. - - .. -... ... ... .. ... - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 TABLE OF CONTENTS {Continued) TABLES TABLE 1 -EARTHWORK SHRINKAGE AND BULKING ESTIMATES-PAGE 9 TABLE 2-2013 CBC MAPPED SPECTRAL ACCELERATION PARAMETERS-PAGE 12 TABLE 3-MINIMUM FOUNDATION AND SLAB DESIGN RECOMMENDATIONS FOR CONVENTIONAL REINFORCED FOUNDATIONS-PAGE 22 TABLE 4-MINIMUM FOUNDATION SETBACK FROM SLOPE FACES-PAGE 24 TABLE 5-PRESOAKING RECOMMENDATIONS BASED ON FINISHED GRADE SOIL EXPANSION POTENTIAL -PAGE 25 TABLE 6-POST-TENSIONED FONDATION DESIGN RECOMMENDATIONS-PAGE 26 TABLE 7 -STATIC EQUIVALENT FLUID WEIGHT (PCF)-PAGE 28 TABLE 8-PRELIMINARY PAVEMENT SECTIONS -PAGE 30 FIGURE AND PLATES FIGURE 1 -SITE LOCATION MAP-REAR OF TEXT PLATE 1 -GEOTECHNICAL MAP -REAR OF TEXT PLATE 2-GEOLOGIC CROSS-SECTION A-A' -REAR OF TEXT APPENDICES APPENDIX A -REFERENCES APPENDIX B -TEST PIT LOGS AND BORING LOGS APPENDIX C-LABORATORY TESTING PROCEDURES AND TEST RESULTS APPENDIX D -GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH GRADING APPENDIX E-ASSOCIATION OF ENGINEERING FIRMS PRACTICING IN THE GEOSCIENCES iii Leighton .. .. .. • • • • - .. --.... -.. .. - ... .. .. .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 1.0 INTRODUCTION We recommend that all individuals utilizing this report read the preceding information sheet prepared by ASFE (the Association of Engineering Firms Practicing in the Geosciences) and the Limitations, Section 7.0, located at the end of this report . 1.1 Purpose and Scope This report presents the results of our geotechnical investigation for the site located at 2200 Afton Way in the City of Carlsbad, California (Figure 1 ). The intent of this report is to provide specific geotechnical conclusions and recommendations for the currently proposed project. 1.2 Site Location and Description The subject property encompasses approximately 3.92 acres of essentially undeveloped land located at 2200 Afton Way in Carlsbad, California (see Site Location Map, Figure 1 ). The site is bordered by Carlsbad Village Drive to the north, and existing residential developments to the east, south, and west. Topographically, the property consists of gently sloping hillside terrain with elevations ranging from a high of approximately 280 feet Mean Sea Level (MSL) near the southwestern property line to a low of approximately 205 feet (MSL) at the property's northeastern corner. Currently, the property is occupied by one residential structure with two sheds. An existing crib wall, approximately 26 foot high and 300 feet long, is located along the north of the boundary of the site and appears to have been constructed during the alignment of Carlsbad Village Drive. It should be noted that the existing cribwall may be impacted by the proposed improvements and require remedial grading activities. Site drainage is presently accomplished through a generally southeasterly trending ravine and ultimately through controlled drainage facilities along Carlsbad Village Drive. Vegetation consists of native grasses and eucalyptus trees over the majority of the site. Site Latitude and Longitude 33.1721°N 117.3268° w Leighton .. • • .. .. • • .. - -... .. -- .. .. .. .. -... - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 1.3 Proposed Development Based on our review of the provided preliminary grading plan by BHA, Inc. {BHA, Inc., 2014), the property will be developed with nine, one-or two-story single-family homes, with associated infrastructure and underground utility improvements. We further understand that the residential structures would utilize conventional continuous footings with slab-on-grade and/or post-tension systems. Building loads are assumed to be typical for these types of relatively light structures . Currently, no structural plans for the proposed buildings are available . Typical cut and fill grading techniques would be required to bring the site to design elevations. Based on our review, cut and fill slopes are proposed at inclinations of 2:1 {horizontal:vertical [H:V]), or flatter, with maximum planned slope heights of about 10 and 23 feet, respectively. Cuts and fills are currently proposed up to about 13 and 12 feet in thickness, respectively, (excluding remedial grading removals). Sewage disposal is understood to be accommodated by tying into the regional municipal system . 2 Leiqhton 'w .. ... .. • .. • .. .. .. -... - - <II .. <II Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 2.1 2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING Site Investigation Our exploration consisted of the excavation, logging, and sampling three large diameter borings (LD-1 through LD-3) and 6 test pit excavations (TP-1 through TP-6). Excavation depths ranging from of approximately 9 feet to 51 feet below the existing ground surface (bgs). The approximate locations of the explorations are shown on the Geotechnical Map (Plate 1 ). Subsequent to the subsurface investigation, the test pits were backfilled with tamped soils and the large diameter boring excavations were backfilled with spoils and layers of bentonite in accordance with the San Diego County DEH Boring Permit Wavier. During the exploration operations, a geologist from our firm prepared geologic logs and collected bulk and undisturbed samples for laboratory testing and evaluation. Logs of the explorations are presented in Appendix B . 2.2 Laboratory Testing Laboratory testing performed on soil samples representative of on-site soils obtained during the recent subsurface exploration included, expansion potential, grain size analysis, corrosion test, direct shear tests on drive samples, moisture test, and atterberg limits. A discussion of the laboratory tests performed and a summary of the laboratory test results are presented in Appendix C . 3 Leighton • - • • 41 .. • • .. --------- .. .. 11 .. - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 3.1 3.0 SUMMARY OF GEOTECHNICAL CONDITIONS Geologic Setting The project area is situated in the Peninsular Ranges Geomorphic Province. This geomorphic province encompasses an area that extends approximately 900 miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja California, and varies in width from approximately 30 to 100 miles (Norris and Webb, 1990). The province is characterized by mountainous terrain on the east composed mostly of Mesozoic igneous and metamorphic rocks, and relatively low-lying coastal terraces to the west underlain by late Cretaceous-age, Tertiary-age, and Quaternary-age sedimentary units. Most of the coastal region of the County of San Diego, including the site, occur within this coastal region and are underlain by sedimentary units. Specifically, the subject site is located within the coastal plain section of the Peninsular Range Geomorphic Province of California, which generally consists of subdued landforms underlain by sedimentary bedrock. 3.2 Site-Specific Geology Based on our subsurface exploration and review of pertinent geologic literature and maps (Appendix A), the geologic units underlying the site consist of localized undocumented artificial fill, colluvium, and slope wash deposits overlying terrace deposits (Quaternary-aged Very Old Paralic Deposits) and Tertiary-age Santiago Formation across the entire site area. A brief description of the geologic units encountered on the site is presented below. The general distribution of earth materials are shown on Plate 1. 3.2.1 Artificial Fill -Undocumented -(Afu) During our subsurface exploration, an approximately 2-to 10-foot thick layer of undocumented artificial fill soils was encountered at several of the exploration locations. The fill was apparently placed during the site's initial construction and isolated deeper fills may exist that were not observed during our exploration. An as-graded report was not available for our review, and it is assumed that no engineering observations of these localized fill soils were provided at the time of grading. These fill soils 4 Leighton .. • - -• • • .. • - -... --- --- -.. -... .. • -.. Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 generally consisted of a mixture of silty sand and sandy clay, are dry, loose and may settle appreciably under additional fill or foundation and improvement loading. Therefore, all undocumented fills (soil} should be removed and recompacted. These materials may be reused provided they are cleared of trash and debris. All trash and debris should be removed, and properly disposed offsite, prior to fill placement and/or remedial grading . 3.2.2 Colluvium (Qc) In general, the southern portion of the site is mantled by a relatively thin layer of colluvium. The colluvium was generally observed to be reddish brown to brown, dry, porous, loose, silty sand. Locally roots and rootlets were noted within these surficial soils. The colluvium was generally encountered ranging from approximately 2 to 4 feet in thickness. Due to the potentially compressible nature of these surficial soils, they are considered unsuitable for the support of structures and/or improvements in their existing state. Therefore, these soils will need to be removed and recompacted, if not removed during planned excavation, should settlement sensitive improvements be proposed within their influence. 3.2.3 Slope Wash Deposits (Qsw) The northern portion of the site is mantled by a layer of slope wash. The slope wash was generally observed to be orange brown to grayish brown, dry to moist, porous, loose, silty sand to clayey sand. The slope wash was generally encountered ranging from 9 to 10 feet in thickness. Due to the potentially compressible nature of these surficial soils, they are considered unsuitable for the support of structures and/or improvements in their existing state. Therefore, these soils will need to be removed and recompacted, if not removed during planned excavation, should settlement sensitive improvements be proposed within their influence. 3.2.4 Very Old Paralic Deposits (Qvop) Quaternary-aged Very Old Paralic Deposits (previously referred to as terrace deposits} underlie the colluvium soils at southern portion site. This unit primarily consists of massively bedded, reddish-to orange brown, 5 Leighton - -• - .. • - • • - -... -.. - - ... --... .. ... - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 oxidized, weakly to moderately cemented, dense to very dense, silty sandstone and clayey sandstone, and are locally weathered near the surface. The weathered near surface Very Old Paralic Deposits (upper 1 to 2 feet), where encountered, should be removed and recompacted, if not removed during planned excavation, should settlement sensitive improvements be proposed within their influence . 3.2.5 Santiago Formation {Tsa) Sandstone, clayey siltstone, and claystone sedimentary bedrock belonging to Eocene-age Santiago Formation, was encountered onsite. These deposits occur at depth within the property. Where unweathered, these rocks are considered suitable for structural support. Bedding structures observed in our large diameter explorations indicate a northwesterly trend with a southeasterly dip on the order of 10 degrees. 3.3 Surface and Ground Water The regional groundwater table was not encountered in the explorations, to a depth of 51 feet deep. Based on our review of the topographic quadrangle map (USGS, 1967), groundwater level are anticipated at least 200 feet below the site surface, which corresponds with Buena Vista Lagoon, north of the subject site. Therefore, we anticipate the lowest site foundations will be well above the existing static ground water table at the site. Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field study. However, seepage may occur locally (due to heavy precipitation or irrigation) in areas where fill soils overlie silty or clayey soils. Such soils may be encountered at the site. Mitigation of seepage may be necessary during site grading. 3.4 Engineering Characteristics of On-site Soils Based on the results of our laboratory testing of representative on-site soils, and our professional experience on similar sites with similar soils conditions, the engineering characteristics of the on-site soils are discussed below . 6 Leighton • .. .. .. .. .. • .. .. • .. • - - - -... - .. .. .. .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 3.4.1 Expansion Potential Laboratory testing was performed to evaluate the expansion index of materials characteristic of the site. The sample tested had an expansion index of 53. Based on our field observations, subsurface investigation, and laboratory testing, low to medium expansive soils are anticipated for this site. High expansive soils may be encountered during site grading in isolated layers. 3.4.2 Compressible Soils Based on our experience on similar projects in the Carlsbad and our site specific exploration, we expect that the upper 2 to 10 feet of the site is underlain by undocumented fill, colluvium, or slope wash deposits which are considered compressible. Recommendations for remedial grading of these soils are provided in the following sections of this report . 3.4.3 Soil Corrosivity A preliminary corrosive soil screening for the on-site materials was completed to evaluate their potential effect on concrete and ferrous metals. The corrosion potential was evaluated using the results of laboratory testing on one representative soil sample obtained during our subsurface evaluation. Laboratory testing was performed to evaluate pH, minimum electrical resistivity, and chloride and soluble sulfate content. The samples tested had a measured pH of 7.19, and a measured minimum electrical resistivity of 8,240 ohm-cm. Test results also indicated that the samples had a chloride content of 62.3 ppm, and a soluble sulfate content of less than 0.015 percent. 3.4.4 Infiltration We performed percolation testing in Percolation Holes P-1 and P-2 to evaluate suitability of the site for infiltration of storm water. The results of the percolation test indicated that the site soils had a percolation rate of greater than 125 minutes per inch (mpi). Generally, a percolation rate less 7 Leighton .. .. .. • • • ... .. .. .. .. Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 than 120 mpi is considered necessary to consider a site suitable for onsite infiltration of storm water. Additionally, the presence of shallow clayey sand and clay materials present in much of the site would be expected to impede infiltration and a 30-mil HOPE should be considered to line any proposed infiltration basins. Further evaluation of proposed LIDs is needed to determine potential down gradient impacts. 3.4.5 Excavation Characteristics The site is underlain by undocumented fill, colluvium, slope wash deposits, Very Old Paralic Deposits, and Santiago Formation generally consisting of silty to clayey sands and sandy claystone to clayey sandstone. With regards to the proposed project, it is anticipated these on-site soils can be excavated with conventional heavy-duty construction equipment. Oversize cobble material (typically over 6 inches in maximum dimension) is present locally in the Paralic Deposits. Oversize cobble material should be placed in non-structural areas or hauled off-site . 3.5 Slope Stability Based on the available data, it is anticipated that proposed fill slopes will be generally stable assuming proper construction and maintenance. Cut slopes, up to proposed heights of 10 feet, that are constructed in Very Old Paralic Deposits and earth materials belonging to Santiago Formation, are also anticipated to be generally stable assuming proper construction and maintenance. However, southeast-facing cut slopes constructed in the Santiago Formation may exhibit adverse (out of slope) bedding orientations and may require stabilization and buttressing. Cut slopes constructed to the anticipated heights in competent bedrock should perform adequately at gradients of 2: 1 (H:V), or flatter, and are considered to be generally stable assuming proper construction and maintenance. Additional site specific analysis may be warranted once final 40-scale grading plans have been developed. All cut slopes constructed will require observation during grading in order to verify the findings and conclusions presented herein . The cut slope in the northwestern portion of the site adjacent to Lot 4 will likely expose slope wash material which will require removal and construction of a buttress replacement fill with a key way at the toe of slope. Recommendations for the buttress/replacement fill is presented on the Geotechnical Map (Plate 1 ) . 8 Leighton • • ◄ • .. ., .. • • • • - .. .. ... ... Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 All slopes may be susceptible to surficial slope instability and erosion given substantial wetting of the slope face. Surficial slope stability may be enhanced by providing proper site drainage. The site should be graded so that water from the surrounding areas is not able to flow over the top of slopes. Diversion structures should be provided where necessary. Surface runoff should be confined to gunite- lined swales or other appropriate devices to reduce the potential of erosion. Slopes should be planted with vegetation that will increase the surficial stability . 3.6 Earthwork Shrinkage and Bulking The volume change of excavated on-site materials upon recompaction as fill is expected to vary with materials and location. Typically, the surficial soils and bedrock materials vary significantly in natural and compacted density, and therefore, accurate earthwork shrinkage/bulking estimate cannot be determined. We do not anticipate significant grading at the site where bulking and shrinkage estimates are necessary. However, if needed, the following factors (based on evaluation of our subsurface investigation, laboratory testing, geotechnical analysis and professional experience on similar sites) are provided on Table 1 as guideline estimates. If possible, we suggest an area where site grades can be adjusted be provided as a balance area. Table 1 Earthwork Shrinkage and Bulking Estimates Geologic Unit Estimated Shrinkage/bulking Colluvium/Undocumented fill 5 to 15 percent shrinkage Slope Wash Deposits 4 to 8 percent shrinkage Paralic Deposits and 2 to 10 percent bulking Santiago Formation 9 LeiQhton " • • - .. • • • - - --.. -- -... - .. .. .. .. • Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 4.1 4.0 SEISMIC AND GEOLOGIC HAZARDS Regional Tectonic Setting During the late Pliocene, several new faults developed in Southern California, creating a new tectonic regime superposed on the flat-lying section of Tertiary and late Cretaceous rocks in the San Diego region. One of these fault systems is the Rose Canyon Fault Zone. The principal known onshore faults in southernmost California are the San Andreas, San Jacinto, Elsinore, Imperial and Rose Canyon faults, which collectively transfer the majority of this deformation. The balance of the plate margin slip, is taken by the offshore zone of faults which include the Coronado Bank, Descanso, San Diego Trough, and San Clemente faults off of the San Diego and northern Baja California coastline. Most of the offshore faults coalesce south of the international border, where they come onshore as the Agua Blanca fault which transects the Baja California peninsula (Jennings, 2010). 4.2 Local Faulting Our review of available geologic literature (Appendix A) indicates that there are no known significant or active or potentially active faults transecting, or projecting toward the site. The nearest active fault is the Rose Canyon / Newport - Inglewood (offshore) fault zone located approximately 6.9 miles west of the site within the Pacific Ocean (Treiman, 1993). 4.3 Seismicity The site can be considered to lie within a seismically active region, as can all of Southern California. As previously mentioned above, the Rose Canyon fault zone located approximately 6.9 miles west of the site, is the 'active' fault considered having the most significant effect at the site from a design standpoint. 4.4 Seismic Hazards Severe ground shaking is most likely to occur during an earthquake on one of the regional active faults in Southern California. The effect of seismic shaking may 10 Leighton • -.. .. • -.. • .. • • .. .. • • --- ---... ---... .. • .. - Geotechnical Investigation. 2200 Afton Way. Carlsbad. California 10690.002 be mitigated by adhering to the California Building Code or state-of-the-art seismic design parameters of the Structural Engineers Association of California . 4.4.1 Shallow Ground Rupture As previously discussed, no faults are mapped transecting or projecting toward the site. Therefore, surface rupture hazard due to faulting is considered very low. Ground cracking due to shaking from a seismic event is not considered a significant hazard either, since the site is not located near slopes . 4.4.2 Mapped Fault Zones The site is not located within a State mapped Earthquake Fault Zone (EFZ). As previously discussed, the subject site is not underlain by known active or potentially active faults . 4.4.3 Site Class Utilizing 2013 California Building Code (CBC) procedures, we have characterized the site soil profile to be Site Class D based on our experience with similar sites in the project area and the results of our subsurface evaluation. 4.4.4 Building Code Mapped Spectral Acceleration Parameters The effect of seismic shaking may be mitigated by adhering to the California Building Code and state-of-the-art seismic design practices of the Structural Engineers Association of California. Provided below in Table 2 are the risk-targeted spectral acceleration parameters for the project determined in accordance with the 2013 California Building Code (CBSC, 2013a) and the USGS Worldwide Seismic Design Values tool (Version 3.1.0). 11 Leighton - .. .. .. "" .. • • .. ---... - - -.. --.. .. -.. - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 Table 2 2013 CBC Mapped Spectral Acceleration Parameters Site Class D Fa = 1.056 Site Coefficients Fv = 1.573 Mapped MCER Spectral Ss = 1.110 Accelerations S1 = 0.427 Site Modified MCER Spectral SMs = 1.172 Accelerations SM1 = 0.672 Sos = 0.781 Design Spectral Accelerations So1 = 0.448 Utilizing ASCE Standard 7-10, in accordance with Section 11.8.3, the following additional parameters for the peak horizontal ground acceleration are associated with the Geometric Mean Maximum Considered Earthquake (MCEG). The mapped MCEG peak ground acceleration (PGA) is 0.432g for the site. For a Site Class D, the FPGA is 1.068 and the mapped peak ground acceleration adjusted for Site Class effects (PGAM) is 0.461 g for the site. 4.5 Secondary Seismic Hazards In general, secondary seismic hazards can include soil liquefaction, seismically- induced settlement, lateral displacement, surface manifestations of liquefaction, landsliding, seiches, and tsunamis. The potential for secondary seismic hazards at the subject site is discussed below. 4.5.1 Liquefaction and Dynamic Settlement Liquefaction and dynamic settlement of soils can be caused by strong vibratory motion due to earthquakes. Granular soils tend to density when subjected to shear strains induced by ground shaking during earthquakes. Research and historical data indicate that loose granular soils underlain by a near surface ground water table are most susceptible to liquefaction, while the most clayey materials are not susceptible to liquefaction . Liquefaction is characterized by a loss of shear strength in the affected soil layer, thereby causing the soil to behave as a viscous liquid. This effect may be manifested at the ground surface by settlement and, 12 Leighton .. • .. • .. - .. - - -- - - - - --- -... - Geotechnical Investigation. 2200 Afton Way. Carlsbad, California 10690.002 possibly, sand boils where insufficient confining overburden is present over liquefied layers. Where sloping ground conditions are present, liquefaction-induced instability can result. The site is underlain at depth by moderately cemented sandstones and moderately well indurated siltstone and claystone. Since loose surficial fill and weathered Very Old Paralic Deposits are recommended for removal, the underlying dense character of the on-site formational deposits, and the lack of a shallow ground water table, it is our opinion that the potential for liquefaction and seismic related settlement across the site is nil. 4.5.2 Lateral Spread Empirical relationships have been derived (Youd et al., 1999) to estimate the magnitude of lateral spread due to liquefaction. These relationships include parameters such as earthquake magnitude, distance of the earthquake from the site, slope height and angle, the thickness of liquefiable soil, and gradation characteristics of the soil. The susceptibility to earthquake-induced lateral spread is considered to be low for the site because of the low susceptibility to liquefaction and relatively level ground surface in the site vicinity. 4.5.3 Tsunamis and Seiches Based on a site elevation of approximately 200 feet msl, and the distance the site is located from the Pacific coastline, there is no potential for flood damage to occur at the site from a tsunami or seiche. 4.6 Landslides Several formations within the San Diego region are particularly prone to landsliding. These formations generally have high clay content and mobilize when they become saturated with water. Other factors, such as steeply dipping bedding that project out of the face of the slope and/or the presence of fracture planes, will also increase the potential for landsliding. 13 Leighton 111 -... - -- - --- .... ---... - - - - .. .. - Geotechnical Investigation, 2200 Afton Wav, Carlsbad, California 10690.002 No landslides or indications of deep-seated landsliding were indicated at the site during our field exploration or our review of available geologic literature, topographic maps, and stereoscopic aerial photographs. Furthermore, our field explorations indicate the site is generally underlain by favorable oriented geologic structure, consisting of sandstone, claystone, and siltstone. Therefore, the potential for significant landslides or large-scale slope instability at the site is considered low. 4. 7 Flood Hazard According to a Federal Emergency Management Agency (FEMA) flood insurance rate map (FEMA, 2012); the site is not located within a floodplain. Based on our review of topographic maps, the site is not located downstream of a dam or within a dam inundation area. Based on this review and our site reconnaissance, the potential for flooding of the site is considered very low. 14 Leiqhton "' 41 -.. - .. .. .. .. .. .. .. .. ---.. ----- - 111 .. • .. - - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 5.0 CONCLUSIONS Based on the results of our geotechnical investigation of the site, it is our opinion that the proposed residential development is feasible from a geotechnical standpoint, provided the following conclusions and recommendations are incorporated into the project plans and specifications . • Generally, loose soils having depths of up to approximately 1 to 10 feet locally underlie the site and are considered compressible. Therefore, these soils are not considered suitable for the support of structural loads or the support of engineered fill soils and site improvements in their present condition. Section 6.1.2 of this report provides specific recommendations regarding mitigation of these soil materials . • The mapped MCEG peak ground acceleration (PGA) is 0.432g for the site, and for site Class D, the mapped peak ground acceleration, adjusted for Site Class effects (PGAM) is 0.461g . • Based on the results of our subsurface explorations and our experience with similar projects in the site area, we anticipate regional ground water to be at a depth of 200 feet or more. Therefore, ground water is not anticipated to be a constraint during site construction, and we do not anticipate that temporary dewatering will be necessary. • The underlying Very Old Paralic Deposits and Santiago Formation are not subject to liquefaction based on their age, generally dense character, and the lack of a shallow ground water table . • The cut slope adjacent to Lot 4 will likely require a buttress/replacement fill to stabilize slope wash material. • Due to the lack of adverse geologic conditions, landsliding and mass movement is considered to be unlikely. However, cut slopes should be evaluated during site grading to verify slope bedding is as anticipated. • Based on the results of our subsurface exploration, we anticipate that the onsite materials should be generally rippable with conventional heavy-duty earthwork equipment. The existing onsite soils are suitable for reuse as engineered fill provided they are relatively free of organic material, debris, and rock fragments larger than 6 inches in maximum dimension. In addition, unknown items such as buried concrete footings left from previous site development should be anticipated . 15 Leighton .. .. .. ... .. .. .. .. .. .. 41 " .. .. " .. .. - - ... .. .. .. .. ◄ .. " .. 11 .. • .. .. .. Geotechnical Investigation. 2200 Afton Way, Carlsbad, California 10690.002 • Based on laboratory testing and visual classification, materials derived from the on- site soil materials possess a low to medium expansion potential. • Although Leighton does not practice corrosion engineering, laboratory test results indicate the soils present on the site have a negligible potential for sulfate attack on normal concrete. However, the onsite soils are considered to be moderately corrosive to buried uncoated ferrous metals . • It should be noted that the existing cribwall at the north east property line may be impacted by the proposed improvements and require remedial grading activities. • The existing onsite soils were found to have a very low permeability and are not considered suitable for storm water management strategies that utilize infiltration . Additional investigation regarding the infiltration characteristics of the site soils will be required before recommendations for the use of infiltration type LID devices can be provided. The proposed infiltration basins should be lined with a 30-mil HDPE liner to prevent lateral migration of storm water. In addition, subsurface improvements down gradient could be affected by some proposed LID measures and should therefore be fully evaluated before being considered . 16 Leighton .. .. .. .. • .. .. ---... -.. • -.. .. .. - .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 6.1 6.0 RECOMMENDATIONS Earthwork We anticipate that earthwork at the site will consist of site preparation, shallow excavation and fill operations. We recommend that earthwork on the site be performed in accordance with the following recommendations and the General Earthwork and Grading Specifications for Rough Grading included in Appendix D. In case of conflict, the following recommendations supersede those in Appendix D . 6.1.1 Site Preparation Prior to grading, all areas to receive structural fill, engineered structures, or hardscape should be cleared of surface and subsurface obstructions, including any existing debris and undocumented, loose, compressible, or unsuitable soils, and stripped of vegetation. Removed vegetation and debris should be properly disposed off site. All areas to receive fill and/or other surface improvements should be scarified to a minimum depth of 8 inches, brought to optimum or above-optimum moisture conditions, and recompacted to at least 90 percent relative compaction based on ASTM Test Method D1557. 6.1.2 Removal of Compressible Soils Potentially compressible undocumented fill soils, colluvium, slope wash deposits, and weathered Paralic Deposits at the site may settle as a result of wetting or settle under the surcharge of engineered fill and/or structural loads supported on shallow foundations. Therefore, remedial grading is recommended across the entire site to remove undocumented fill, colluvium, slope wash deposits, and weathered Paralic Deposits. These soils should be removed to undisturbed Paralic Deposits ("Formation") and/or Santiago Formation and replaced as moisture conditioned engineered fill. In general, removal depths will range from 2 to 10 feet below the existing ground surface across the site. The removal depths should extend to a depth of at least 4 feet below finished building pad grade. The lateral limits of the removal bottom should extend at least 5 17 Leiqhton "' .. .. .. .. .. • 41 .. ----... ..., -.. - - ... .. .. Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 feet beyond the foundation limits. The bottom of all removals should be evaluated by a Certified Engineering Geologist to confirm conditions are as anticipated. In general, the soil that is removed may be reused and placed as engineered fill provided the material is moisture conditioned to at least 2 percent above optimum moisture content, and then recompacted prior to additional fill placement or construction. Soil with an expansion index greater than 70 should not be used within 5 feet of finish grade in the building pad. The actual depth and extent of the required removals should be confirmed during grading operations by the geotechnical consultant. 6.1.3 Cut/Fill Transition Mitigation Our review of the preliminary grading plans indicates that several lots may result in the creation of cut/fill transitions. The introduction of materials (fill compared to native sandstone) having differing permeability and density into the site may create a condition where surface infiltration of water may accumulate below grade. As such, overexcavation of the Paralic Deposits should be sloped at 1 percent toward the streets or deeper fills. To mitigate the impact of the underlying cut/fill transition condition beneath possible structures that are planned across existing or future cut/fill transitions, the cut portion should be over-excavated to at least 3 feet below the bottoms of proposed foundations. The overexcavation should laterally extend at least 5 feet beyond the building pad area and all associated settlement-sensitive structures. The over-excavated material should be replaced with properly compacted fill. Maximum to minimum fill thickness within a given lot should not exceed ratio of 3:1. As such, deeper over excavation will be necessary for fill lots with maximum fills in excess of approximately 9 feet. Final overexcavation depths should be determined and documented in the field based on site conditions. 6.1.4 Excavations and Oversize Material Excavations of the onsite materials may generally be accomplished with conventional heavy-duty earthwork equipment. Due to the generally friable nature of the fill and Paralic Deposits, temporary excavations, such as utility trenches with vertical sides, may slough over time . 18 Leighton .. .. .. .. .. -.. • .. ,.. .. -.. ---... .. ... ---.. .. .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 In accordance with OSHA requirements, excavations deeper than 5 feet should be shored or be laid back if workers are to enter such excavations . Temporary sloping gradients should be determined in the field by a "competent person" as defined by OSHA. For preliminary planning, sloping of fill soils at 1 :1 (horizontal to vertical) may be assumed . Excavations supporting structures or greater than 20 feet in height will require an alternative sloping plan or shoring plan prepared by a California registered civil engineer . 6.1.5 Engineered Fill In areas proposed to receive engineered fill, the existing upper 8 inches of subgrade soils should be scarified then moisture conditioned to moisture content at or above the optimum content and compacted to 90 percent or more of the maximum laboratory dry density, as evaluated by ASTM D 1557. Soil materials utilized as fill should be free of oversized rock, organic materials, and deleterious debris. Rocks greater than 6 inches in diameter should not be placed within 2 feet of finished grade. Fill should be moisture conditioned to at least 2 percent above the optimum moisture content and compacted to 90 percent or more relative compaction, in accordance with ASTM D 1557. Although the optimum lift thickness for fill soils will be dependent on the type of compaction equipment utilized, fill should generally be placed in uniform lifts not exceeding approximately 8 inches in loose thickness . In vehicle pavement areas, the upper 12 inches of subgrade soils should be scarified then moisture conditioned to a moisture content above optimum content and compacted to 95 percent or more of the maximum laboratory dry density, as evaluated by ASTM D 1557. Placement and compaction of fill should be performed in general accordance with current City of Carlsbad grading ordinances, California Building Code, sound construction practice, these recommendations and the General Earthwork and Grading Specifications for Rough Grading presented in Appendix D . 19 Leighton ... 111 .. .. - - .. -.... -.. .. -.... -------.. -.... -.. .. .. Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 6.1.6 Import Soils If import soils are necessary to bring the site up to the proposed grades, these soils should be granular in nature, environmentally clean, have an expansion index less than 50 (per ASTM Test Method D4829) and have a low corrosion impact to the proposed improvements. Import soils and/or the borrow site location should be evaluated by the geotechnical consultant prior to import. The contractor should provide evidence that all import materials comply with DTSC requirements for import materials. 6.1. 7 Expansive Soils and Selective Grading Based on our laboratory testing and observations, we anticipate the onsite soil materials possess a low to medium expansion potential (Appendix C). Should an abundance of medium to highly expansive materials be encountered, selective grading may need to be performed, such as placing these materials in the deeper portions of the planned fill areas. In addition, to accommodate conventional foundation design, the upper 5 feet of materials within the building pad and 5 feet outside the limits of the building foundation should have a very low to low expansion potential (El<70) . 6.1.8 Buttress/Replacement Fill Based on our subsurface exploration (Appendix B), we anticipate the cut slope in the north western portion of the site adjacent to Lot 4 may be surficially unstable and may require the construction of buttress or replacement fill. The replacement fill key should be constructed a minimum of 15 feet wide, at least 2 feet below the toe-of-slope grade, and have a minimum 2 percent into-the-slope inclination. The approximate location of the replacement fill key is presented on the Geotechnical Map (Plate 1.) A typical detail for stability fill construction is provided in the attached General Earthwork and Grading Specifications (Appendix D). 20 Leighton -.. - .. .. .. -.... ---... -... - ""' - -... - - .. Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 6.2 Foundation and Slab Considerations At the time of drafting this report, building loads were not known. However, based on our understanding of the project, the proposed residential buildings may be constructed with conventional foundations or post-tensioned foundations. In general foundations and slabs should be designed in accordance with structural considerations and the following recommendations. The foundation recommendations below assume that the all building foundations will be underlain by properly compacted fill. 6.2.1 Conventional Foundations Conventionally reinforced foundations should be designed and constructed in accordance with the recommendations contained in Table 3 based on a very low to low expansion potential. Residential structures placed on deep fill areas (considered to be greater than 40 feet in depth), underlain by differential fill thicknesses of 20 or more feet, and/or having moderate to highly expansive soils (an expansive potential greater than 51) at finish grade should be constructed with a post-tension foundation (as indicated in Section 6.2.5) instead of a conventional reinforced foundation. 21 Leighton .. -... -- -... - - - - -.... ---... --- .. ... .. .. .. .. - Geotechnical Investigation, 2200 Afton Way, Carlsbad. California 10690.002 Table 3 Minimum Foundation and Slab Desian Recommendations For Conventional Reinforced Foundations Design Criteria Minimal Fill Thickness, Minimal Fill Differential, and a Very Low to Low Expansion Potential (an Expansion Potential less than 50) I-Story Footings All footings 12 inches deep. Reinforcement for continuous footings: two (See Note 1) No. 5 bar top and bottom. 2-Story Footings All footings 18 inches deep. Reinforcement for continuous footings: two (See Note 1) No. 5 bar top and bottom. Minimum Footing Width Continuous: 12 inches for 1-story Continuous: 15 inches for 2-story Isolated column: 24 inches (18 inches deep minimum) Garage Door Grade Beam A grade beam 12 inches wide and 18 inches deep (SeeNote2) should be provided across the garage entrance. Living Area Floor Slabs Minimum 5 inch thick slab with No. 3 bars@ 18 inches on center, each (See Notes 3, 4 and 6) way (at mid-height) on 2 inches clean sand over moisture barrier over 2 inches clean sand. Garage Floor Slabs Minimum 5 inch thick concrete slab with No. 3 bars @ 18 inches on center, (See Notes 4, 5 and 6) each way (at mid-height) on 2 inches sand base over moisture barrier on pad. Slab should be quarter-sawn. Presoaking of Living Area 120 percent of the optimum moisture content to a depth of 12 inches. and Gara2e Slabs (see note) Allowable Bearing Capacity 2,000 pounds per square foot (one-third increase for short term loading) Expected Foundation Deflection: 1/2 inch in 50 feet Notes: (1) (2) (3) (4) (5) (6) (7) (8) Depth of interior or exterior footing to be measured from lowest adjacent finish grade or drainage swale flowtine elevation. The base of the grade beam should be at the same elevation as that of the adjoining footings. Living area slabs should be tied to the footings as directed by the structural engineer. 10-mil non-recycled plastic sheeting is acceptable. Equivalents are acceptable. All laps and penetrations should be sealed. Garage slabs should be isolated from stem wall footings with a minimum 3/8-inch expansion joint. Sand base should have a Sand Equivalent of 30 or greater ( e.g. washed concrete sand). Where the foundation is within 3 feet (horizontally) of adjacent drainage swales, the adjacent footing should be embedded a minimum depth of 12 inches below the swale flow line. The recommendations presented above assume that proper maintenance irrigation and drainage are maintained around the structure . The vapor barrier recommended in Table 2 should be sealed at all penetrations and laps. Moisture vapor transmission may be additionally reduced by use of concrete additives. Moisture barriers can retard but not eliminate moisture vapor movement from the underlying soils up through the slabs. We recommend that the floor covering installer test the moisture vapor 22 Leighton - ... ... -.. - .. .. - - .... -... --- - - -... -... - "' -.. • Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 flux rate prior to attempting applications of the flooring. "Breathable" floor coverings should be considered if the vapor flux rates are high. A slipsheet or equivalent should be utilized above the concrete slab if crack-sensitive floor coverings (such as ceramic tiles, etc.) are to be placed directly on the concrete slab. Our experience indicates that use of reinforcement in slabs and foundations will generally reduce the potential for drying and shrinkage cracking. However, some cracking should be expected as the concrete cures. Minor cracking is considered normal; in addition, it is often aggravated by a high water content, high concrete temperature at the time of placement, small nominal aggregate size, and rapid moisture loss due to hot, dry and/or windy weather conditions during placement and curing. Cracking due to temperature and moisture fluctuations can also be expected. The use of low water content concrete can reduce the potential for shrinkage cracking. The slab subgrade soils underlying the conventional foundation systems should be presoaked as indicated in Section 6.2.4 prior to placement of the moisture barrier and slab concrete. 6.2.2 Foundation Setback We recommend a minimum horizontal setback distance from the face of slopes for all structural foundations, footings, and other settlement- sensitive structures as indicated on the Table 4 below. The minimum recommended setback distance from the face of a retaining wall is equal to the height of the retaining wall. The distance is measured from the outside bottom edge of the footing, horizontally to the slope or retaining wall face, and is based on the slope or wall height. However, the foundation setback distance may be revised by the geotechnical consultant on a case-by-case basis if the geotechnical conditions are different than anticipated . 23 Leighton -.. - -... -... - - - - ------- - - .. -... -.. -... - Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 Table 4 Minimum Foundation Setback from Slope Faces Slope Height Setback less than 5 feet 5 feet 5 to 15 feet 7 feet Please note that the soils within the structural setback area possess poor lateral stability, and improvements (such as retaining walls, sidewalks, fences, pavements, etc.) constructed within this setback area may be subject to lateral movement and/or differential settlement. Potential distress to such improvements may be mitigated by providing a deepened footing or a grade beam foundation system to support the improvement. In addition, open or backfilled utility trenches that parallel or nearly parallel structure footings should not encroach within an imaginary 1: 1 (horizontal to vertical) downward sloping line starting 9 inches above the bottom edge of the footing and should also not be located closer than 18 inches from the face of the footing. Deepened footings should meet the setbacks as described above. Also, over-excavation should be accomplished such that deepening of footings to accomplish the setback will not introduce a cut/fill transition bearing condition. Where pipes cross under footings, the footings should be specially designed. Pipe sleeves should be provided where pipes cross through footings or footing walls and sleeve clearances should provide for possible footing settlement, but not less than 1 inch around the pipe. 6.2.3 Settlement Fill depths between 3 and 13 feet are anticipated beneath the proposed building foundations following final grading. For conventional footings, the recommended allowable-bearing capacity is based on a maximum total and differential static settlement of 3/4 inch and 1/2 inch, respectively. Since settlements are a function of footing size and contact bearing pressures, some differential settlement can be expected where a large 24 Leighton .. .. --- - --.. --- -... ------- - - .. ... .. .. - - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 differential loading condition exists. However for most cases, differential settlements are considered unlikely to exceed 1/2 inch. 6.2.4 Moisture Conditioning The slab subgrade soils underlying the foundation systems should be presoaked in accordance with the recommendations presented in Table 5 prior to placement of the moisture barrier and slab concrete. The subgrade soil moisture content should be checked by a representative of Leighton prior to slab construction. Presoaking or moisture conditioning may be achieved in a number of ways. But based on our professional experience, we have found that minimizing the moisture loss on pads that has been completed (by periodic wetting to keep the upper portion of the pad from drying out) and/or berming the lot and flooding for a short period of time (days to a few weeks) are some of the more efficient ways to meet the presoaking recommendations. If flooding is performed, a couple of days to let the upper portion of the pad dry out and form a crust so equipment can be utilized should be anticipated. Table 5 Presoaking Recommendations Based on Finish Grade Soil Expansion Potential Expansion Potential Presoaking Recommendations Very Low Near-optimum moisture content to a minimum depth of 6 inches Low 120 percent of the optimum moisture content to a minimum depth of 12 inches below slab suborade Medium 130 percent of the optimum moisture content to a minimum depth of 18 inches below slab subgrade High 130 percent of the optimum moisture content to a minimum depth of 24 inches below slab subgrade 25 Leighton .. --- - - ---... - --------.. - .. .. -... .. Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 6.2.5 Post-Tension Foundation Recommendations As an alternative to the conventional foundations for the buildings, post- tensioned foundations may be used. We recommend that post-tensioned foundations be designed using the geotechnical parameters presented in table below and criteria of the 2013 California Building Code and the Third Edition of Post-Tension Institute Manual. A post-tensioned foundation system designed and constructed in accordance with these recommendations is expected to be structurally adequate for the support of the buildings planned at the site provided our recommendations for surface drainage and landscaping are carried out and maintained through the design life of the project. Based on an evaluation of the depths of fill beneath the building pads, the attached Table 6 presents the recommended post-tension foundation category for residential buildings for this site. Table 6 Post-Tensioned Foundation Design Recommendations Category I Catego(l! 11 Catego(l! Ill Very Low to Medium High Low Design Criteria Expansion Expansion Expansion Potential Potential Potential (El 50 to 90) (El 90 to 130) (El Oto 50) Edge Center 9.0 feet 8.3 feet 7.0 feet Moisture Lift: Variation, Edge 4.8 feet 4.2 feet 3.7 feet em Lift: Center 0.46 inches 0.75 inches 1.09 inches Differential Lift: Swell, Ym Edge 0.65 inches 1.09 inches 1.65 inches Lift: Perimeter Footing 18inches 24inches 30inches Depth: Allowable Bearing 2,000 psf Capacity 26 Leighton .. • .. • -- .. • .. -------.. - • ... .. ... -.. - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 The post-tensioned (PT) foundation and slab should also be designed in accordance with structural considerations. For a ribbed PT foundation, the concrete slabs section should be at least 5 inches thick. Continuous footings (ribs or thickened edges) with a minimum width of 12 inches and a minimum depth of 12 inches below lowest adjacent soil grade may be designed for a maximum allowable bearing pressure of 2,000 pounds per square foot. For a uniform thickness "mat" PT foundation, the perimeter cut off wall should be at least 8 inches below the lowest adjacent grade. However, note that where a foundation footing or perimeter cut off wall is within 3 feet (horizontally) of adjacent drainage swales, the adjacent footing should be embedded a minimum depth of 12 inches below the swale flow line. The allowable bearing capacity may be increased by one-third for short-term loading. The slab subgrade soils should be presoaked in accordance with the recommendation presented in Table 5 above prior to placement of the moisture barrier. The slab should be underlain by a moisture barrier as discussed in Section 6.2.1 above. Note that moisture barriers can retard, but not eliminate moisture vapor movement from the underlying soils up through the slabs. We recommend that the floor covering installer test the moisture vapor flux rate prior to attempting applications of the flooring. "Breathable" floor coverings should be considered if the vapor flux rates are high. A slip- sheet or equivalent should be utilized above the concrete slab if crack- sensitive floor coverings (such as ceramic tiles, etc.) are to be placed directly on the concrete slab. Additional guidance is provided in ACI Publications 302.1 R-04 Guide for Concrete Floor and Slab Construction and 302.2R-06 Guide for Concrete Slabs that Receive Moisture-Sensitive Floor Materials. 6.3 Lateral Earth Pressures and Retaining Wall Design Table 7 presents the lateral earth pressure values for level or sloping backfill for walls backfilled with and bearing against fully drained soils of very low to low expansion potential (less than 50 per ASTM D4829) . 27 LeiQhton "" .. .. • .. .. • • .. .. .. .. ----.. "" - -... .. .. .. .. .. ... --- Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 Table 7 Static Equivalent Fluid Weight (pcf) Conditions Level 2:1 Slope Active 35 55 At-Rest 55 65 Passive 350 150 (Maximum of 3 ksf) (sloping down) Walls up to 10 feet in height should be designed for the applicable pressure values provided above. If conditions other than those covered herein are anticipated, the equivalent fluid pressure values should be provided on an individual case-by-case basis by the geotechnical engineer. A surcharge load for a restrained or unrestrained wall resulting from automobile traffic may be assumed to be equivalent to a uniform lateral pressure of 75 psf which is in addition to the equivalent fluid pressure given above. For other uniform surcharge loads, a uniform pressure equal to 0.35q should be applied to the wall. The wall pressures assume walls are backfilled with free draining materials and water is not allowed to accumulate behind walls. A typical drainage design is contained in Appendix D. Wall backfill should be compacted by mechanical methods to at least 90 percent relative compaction (based on ASTM D1557). If foundations are planned over the backfill, the backfill should be compacted to 95 percent. Wall footings should be designed in accordance with the foundation design recommendations and reinforced in accordance with structural considerations. For all retaining walls, we recommend a minimum horizontal distance from the outside base of the footing to daylight as outlined in Section 6.2.2. Lateral soil resistance developed against lateral structural movement can be obtained from the passive pressure value provided above. Further, for sliding resistance, the friction coefficient of 0.35 may be used at the concrete and soil interface. These values may be increased by one-third when considering loads of short duration including wind or seismic loads. The total resistance may be taken as the sum of the frictional and passive resistance provided that the passive portion does not exceed two-thirds of the total resistance . To account for potential redistribution of forces during a seismic event, retaining walls providing lateral support where exterior grades on opposites sides differ by more than 6 feet fall under the requirements of 2013 CBC Section 1803.5.12 28 Leighton ---... - -.. ... • • .. .. .. • --- - .. - .. -... - - - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 and/or ASCE 7-10 Section 15.6.1 and should also be analyzed for seismic loading. For that analysis, an additional uniform lateral seismic force of 8H should be considered for the design of the retaining walls with level backfill, where H is the height of the wall. This value should be increased by 150% for restrained walls . 6.4 Geochemical Considerations Concrete in direct contact with soil or water that contains a high concentration of soluble sulfates can be subject to chemical deterioration commonly known as "sulfate attack." Soluble sulfate results (Appendix C) indicated negligible soluble sulfate content. We recommend that concrete in contact with earth materials be designed in accordance with Section 4 of ACI 318-11 (ACI, 2011 ). Based on our experience in the site vicinity and laboratory tests, the site soils have a moderately corrosion potential to buried uncoated metal conduits. We recommend measures to mitigate corrosion be implemented during design and construction. 6.5 Concrete Flatwork Concrete sidewalks and other flatwork (including construction joints) should be designed by the project civil engineer and should have a minimum thickness of 4 inches. For all concrete flatwork, the upper 12 inches of subgrade soils should be moisture conditioned to at least 3 percent above optimum moisture content and compacted to at least 90 percent relative compaction based on ASTM Test Method D1557 prior to the concrete placement. 6.6 Preliminary Pavement Design The preliminary pavement section design below is based on an assumed Traffic Index (Tl), our visual classification of the subject site soils, experience with other projects in the area, and our limited laboratory testing. Actual pavement recommendations should be based on R-value tests performed on bulk samples of the soils that are exposed at the finished subgrade elevations across the site at the completion of the mass grading operations. Flexible pavement sections have been evaluated in general accordance with the Caltrans method for flexible 29 Leighton ... .. ---... ----- - ------- - ---... -.... -.. - --- Geotechnical Investigation. 2200 Afton Way, Carlsbad. California 10690.002 pavement design. Based on an assumed R-value of 10, preliminary pavement sections for planning purposes is given in Table 8 below: Table 8 Preliminary Pavement Sections Assumed Traffic Asphalt Concrete Aggregate Base Index {Tl) (inches) (inches) 4.5 4.0 5.0 5.0 4.0 6.0 6.0 4.0 13.0 Prior to placement of the aggregate base, the upper 12 inches of subgrade soils should be scarified, moisture-conditioned to at least optimum moisture content and compacted to a minimum 95 percent relative compaction based on American Standard of Testing and Materials (ASTM) Test Method D1557. Class 2 Aggregate Base or Crushed Aggregate Base should then be placed and compacted at a minimum 95 percent relative compaction in accordance with ASTM Test Method D1557. The aggregate base material (AB) should be a maximum of 6 inches thick below the curb and gutter and extend a minimum of 6 inches behind the back of the curb. The AB should conform to and placed in accordance with the approved grading plans, and latest revision of the Standard Specifications Public Works Construction (Greenbook). The Asphalt Concrete (AC) material should conform to Caltrans Standard Specifications, Sections 39 and 92, with a Performance Grade (PG) of 64-10, and the City of Carlsbad requirements. The placement of the AC should be in accordance with the approved grading plans, Section 203-6 of the "Greenbook" Standard Specifications for Public Works Construction, and the City of Carlsbad requirements. AC sections greater than 3-inches thick, should be placed in two lifts. The 1st lift should be a 2-inch minimum base course consisting of a 3/4-inch maximum coarse aggregate. The 2nd lift should be a 2-inch minimum surface capping course consisting of a 1/2-inch maximum coarse aggregate. No single lift shall be greater than 3 inches. If pavement areas are adjacent to heavily watered landscaping areas, we recommend some measures of moisture control be taken to prevent the subgrade 30 Leighton ... --- ---... ---.. -.. .. ----- - ... - - - - Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 soils from becoming saturated. It is recommended that the concrete curbing, separating the landscaping area from the pavement, extend below the aggregate base to help seal the ends of the sections where heavy landscape watering may have access to the aggregate base. Concrete swales should be designed if asphalt pavement is used for drainage of surface waters. 6.7 Control of Ground Water and Surface Waters Regarding Low Impact Development (LID) measures, we are of the opinion that bioswales, infiltration basins, and other onsite storm water retention and infiltration systems can potentially create adverse perched ground water conditions both on- site and off-site. Therefore, given the site geologic conditions, impermeable subsurface material, and project type, infiltration type LID measures are not considered to be appropriate for this site and project. 30 mil HOPE Liners should be used where detention areas are proposed near slopes or retaining walls, near buildings, or over utilities . Surface drainage should be controlled at all times and carefully taken into consideration during precise grading, landscaping, and construction of site improvements. Positive drainage (e.g., roof gutters, downspouts, area drains, etc.) should be provided to direct surface water away from structures and improvements and towards the street or suitable drainage devices. Ponding of water adjacent to structures or pavements should be avoided. Roof gutters, downspouts, and area drains should be aligned so as to transport surface water to a minimum distance of 5 feet away from structures. The performance of structural foundations is dependent upon maintaining adequate surface drainage away from structures. Water should be transported off the site in approved drainage devices or unobstructed swales. We recommend a minimum flow gradient for unpaved drainage within 5 feet of structures of 2 percent sloping away. The impact of heavy irrigation or inadequate runoff gradient can create perched water conditions, resulting in seepage or shallow ground water conditions where previously none existed. Maintaining adequate surface drainage and controlled irrigation will significantly reduce the potential for nuisance-type moisture problems. To reduce differential earth movements such as heaving and shrinkage due to the change in moisture content of foundation soils, which may cause distress to a structure and improvements, moisture content of the soils surrounding 31 Leighton .. .. .. -.... -----• • ------ ---.. .. .. -- Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 the structure should be kept as relatively constant as possible. Below grade planters should not be situated adjacent to structures or pavements unless provisions for drainage such as catch basins and drains are made . All area drain inlets should be maintained and kept clear of debris in order to function properly. In addition, landscaping should not cause any obstruction to site drainage. Rerouting of drainage patterns and/or installation of area drains should be performed, if necessary, by a qualified civil engineer or a landscape architect. All area drain inlets should be maintained and kept clear of debris in order to function properly. In addition, landscaping should not cause any obstruction to site drainage. Rerouting of drainage patterns and/or installation of area drains should be performed, if necessary, by a qualified civil engineer or a landscape architect. 6.8 Construction Observation The recommendations provided in this report are based on preliminary design information and subsurface conditions disclosed by widely spaced excavations. The interpolated subsurface conditions should be checked by Leighton and Associates, Inc. in the field during construction. Construction observation of all onsite excavations and field density testing of all compacted fill should be performed by a representative of this office. We recommend that all excavations be mapped by the geotechnical consultant during grading to determine if any potentially adverse geologic conditions exist at the site. 6.9 Plan Review Final project grading and foundation plans should be reviewed by Leighton and Associates as part of the design development process to ensure that recommendations in this report are incorporated in project plans. 32 Leighton • ---... --- • • --- -- ----- - - -.. ---- Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 7.0 LIMITATIONS The conclusions and recommendations presented in this report are based in part upon data that were obtained from a limited number of observations, site visits, excavations, samples, and tests. Such information is by necessity incomplete. The nature of many sites is such that differing geotechnical or geological conditions can occur within small distances and under varying climatic conditions. Changes in subsurface conditions can and do occur over time. Therefore, the findings, conclusions, and recommendations presented in this report can be relied upon only if Leighton has the opportunity to observe the subsurface conditions during grading and construction of the project, in order to confirm that our preliminary findings are representative for the site. 33 Leighton - --- --- ----- -------• -.. - -.. - --- Figure and Plates Project: 10690.002 Eng/Geol: BEV/MOJ Scale:1 ""' 2,000' Date: September 201◄ Base Map: ESRI ArcGIS OnNne 201◄ Thematic Information: Leighton A&Jhor: (mmurphy) Map Saved 1s P:'dr1fting\10690'002'GIS'<>f_2014-09-1t'Flgure1.mlld on t/HU2014 8:15:17 AM SITE LOCATION MAP 2200 Afton Way Carlsbad, California Figure 1 Leighton , ... · .... ~ ~-. -~~ -==:::: X (lllJ)JIIOU.•.-.Jll ! ! _i 2 < N i---------'---------1-____L_----L--,--:i~ I --t--'r I : .. /; 2 f :' I I -i- <I ' ........ H ... , . I, T: I : I '. (=J T ' ,i l: ; . ·t······· · 1!· ... J : ' ........ , : . .I.. 0 : ~ ..... f -----t---I ,-i-,---~---·-·1-···. I : I l -··~·-·· t--·~·-ij_·1- ' ,I I : I ------I· -11+ I t ' ' .. 'l.i ..... , ...... i ji ' ~ ----~ ' -I ····-t .. ' ,c(r----r-'--t--r---ir--+---l ! w .. $. ~ ! i I 3 I l ~ ;;: ~ f i z s 0 s fi f ~ n t ,1, ! i -~ i .. ~~ w Q o•· i ~~i ii ! " ~ I 0 ~ .. C lil . " • r r. ,; ... .. .. • .. .. -... ... .. .. ... .. Appendix A References ... .. .. .. • • --... - • .. • -... -... .. • .. • • --- - .. ... .. .. - .. ... -... - .,. ... -- - -... - - -... - -- Geotechnical Investigation, 2200 Afton Way. Carlsbad, California APPENDIX A REFERENCES 10690.002 California Geologic Survey {CGS), 2007, Fault Rupture Hazard Zones in California, Special Publication No. 42, Revised 2007 (Interim Version). California Building Standards Commission (CBSC), 2013, California Building Code, Volumes 1 and 2. FEMA, 2012, Flood Insurance Maps, Panel 1035 of 2375, dated May 16 . Jennings, C.W., 2010, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, California Geologic Map Series, Map No. 6 Kennedy, M.P., and Tan, S.S., 2007, Geologic Map of the Oceanside Quadrangle, California, California Geologic Survey, 1:100,000 scale . Kennedy, M.P. and Tan, S.S., 2005, Geologic Map of the San Diego 30' X 60' Quadrangle, California Compiled by Michael P. Digital Preparation by Kelly R. Bovard, Anne G. Garcia and Diane Burns, California Geological Survey. Tan, S.S., and Kennedy, M.P, 1996, Geologic Maps of the Northwestern Part of San Diego County, California, Plate 1, Scale 1 :24,000 . Treiman, J.A., 1993, The Rose Canyon Fault Zone, Southern California: California Division of Mines and Geology, Open File Report 93-02, 45p. United States Department of Agriculture, 1953, Aerial Photographs, Flight AXN-8M, Numbers 75 and 76, scale approximately 1 :24,000, dated March 31. A-1 ... - - ... • .. • .. .. - -.. - .. .. .. All - - -- Appendix B Test Pit and Boring Logs 11 l I It a I 11 1 I lit ii I 11 Al al al ill t 1 1 I 11 i I 1 j LOG OF TRENCH: .L.1 Project Name: Afton Way Logged by: ___ B""-1..V ____________ , ENGINEERING PROPERTIES Project Number: 10690 002 Elevation-254 feet mean sea level Equipment: Baci<boe Location/Grid: _ __._.$0 ... , .... 1tb .... e ... m..__ ________ _ uses Sample Moisture Density GEOLOGIC DATE· 6/12/14 DESCRIPTION· GEOLOGIC No. {%) (pcf) ATTITUDES · · UNIT COLLUVIUM Qc @ 0-2': Silty SAND, brown, dry, loose; roots and rootlets, porous, fine to SM medium grained, weakly cemented VERY OLD PARALIC DEPOSITS Qvop @ 2'-11 ': Silty SAND, orang-brown, dry, medium dense to very dense with SM 8-1 depth; massive @ 0'-4' GRAPHICAL REPRESENTATION: SCALE: 1°=5' SURFACE SLOPE: 2-4°NE TREND: \!t_,) ' :t , ½ -~) 4· / \ .d---f-_·{;_._1-· *\ ' \ \ ,.. >,. .... r-~-. _.,,. ', • i , ' . \ Total Depth= 11 Feet \ . /,\ I , ,;· No Ground Water Encountered ('\ . • : Backfilled: 6112/14 \ ! :f r I . K. ti &I 11 ti ii 11 11 1 I l I 11 ti I It I ti ti al 1 I 11, a LOG OF TRENCH: _ _.T=-2...._ __ _ Project Name: &flea Way_ Logged by: RV ENGINEERING PROPERTIES Project Number: 10890 002 Elevation· 242 feet mean sea level Equipment: Backhoe Location/Grid: Middle S011tb Sample Moisture Density uses GEOLOGIC DATE: 6/12/14 DESCRIPTION: GEOLOGIC No. (%) (pcf) ATTITUDES UNIT COLLUVIUM Qc @ 0-2': Silty SAND, dark brown, dry, loose SM B-1 Qvop @ VERY OLD PARALIC DEPOSITS 0'-4' @ 2'-4': Silty SAND, orange brown to reddish brown, dry, medium dense to SM dense with depth; massive, grades into clayey sand at 4 feet TSA 8-2 SANTIAGO FORM,6 TION @ 8'-12' @4'-12': Clayey SANDSTONE, light brown, moist, very stiff, massive, caliche SC strings along fractures GRAPHICAL REPRESENTATION: SCALE: 1 "=5' SURFACE SLOPE: 2-4°NE TREND: J ---------~i -~ ·. </ 2 )l...r \.~. \ L---t \ ' ' ' ' ' ' < , 1// .. 1/i '· / ~,,-</~'/ ·/ \ //~ ,,,,,,/ ~1/ Total Depth= 12 Feet k2j No Ground Water Encountered ' 0 Backfilled: 6/12/14 .. 1 I i I t I a t • I a I l I i I s I 1 I • I • I t I t • • I 11 I l I t t .t t LOG OF TRENCH: I=3 Project Name: AftQD Way_ Logged by: RV ENGINEERING PROPERTIES Project Number: 10690 002 Elevation-256 feet mean sea level Equipment Backhoe Location/Grid: Middle West Sample Moisture Density uses GEOLOGIC DATE: 6/12/14 DESCRIPTION: GEOLOGIC No. (%) (pcf) ATTITUDES UNIT COLLUVIUM Qc @ 0-2': Silty SAND, dark brown, dry, loose; roots and rootlets, porous SM VERY OLD PARALIC DEPOSITS Qvop @2'-7': Silty SAND, reddish brown, dry, dense SM 8-1 @ 7': Gravel lense @ 2'-3' @7'-12': Silty SAND, orange-brown, dry to moist, very dense GRAPHICAL REPRESENTATION: SCALE: 1 ~=5' SURFACE SLOPE: 2-3°NE TREND: ~ l ./ ····-=..-., . ...,_ .... _ ••"'•'•"•" h"'"" ·0 '' {• • i ' J • ~ ) • ·5 ) .. ' . . / I -/ \ \ : \ . \-\\ \·\ \JL w \ \ ' ~ -\ . ' \h~~' ,:;. \ \' \ I ~; • i . ,, '. ' -~ 1 < '!. ... ~ 1 .y·. \Y . ' Total Depth • 12 Feet \ \'· '. No Ground Water Encountered Backfilled: 6/12/14 l I t I • I • t • I • I ;. I i I i I I I • I a I • I • I • I i I i I i I J I Project Name: Afton Way Logged by: RV Project Number: 1Q690 002 Elevation: 254 feet mean sea level Equipment BacJcboe Location/Grid: Soutbero GEOLOGIC ATTITUDES I DATE: 6/12/14 DESCRIPTION: COLLUVIUM @0-4': Silty SAND, brown, dry, loose, roots and rootlets VERY_OLD PARALIC DEPOSITS @ 4'-8': Silty SAND, orange-brown, dry, dense, massive @ 8'-1 O': Becomes very dense LOG OF TRENCH: _....,.T....,--4....._ __ _ ENGINEERING PROPERTIES GEOLOGIC I uses I Sample I Moisture I Density UNIT No. (%) (pcf) QC I SM I Qvop I SM GRAPHICAL REPRESENTATION: SCALE: 1 "=5' SURFACE SLOPE: 1-2°NE TREND: \-'x ~<}{" V ~ 1 l , r 1 ~ \ .\ i -.\-1 ·\. ~1· ·•v·· -* ; ..., , : \~, lJ -Total Depth = 10 Feet No Ground Water Encountered Backfilled: 6/12/14 t I l I A I a I i j A f I I j I l I i I i I 6 I A t A I ll I l I i I 1 t l I LOG OF TRENCH: _...,I=-5...__ __ _ Project Name: AttoaWa'f,. Logged by: RV ENGINEERING PROPERTIES Project Number: 10690 002 Elevation-264 feet mean sea level Equipment Backbce Location/Grid: S011thPm GEOLOGIC uses Sample Moisture Density DATE:v6/12/14 DESCRIPTION: GEOLOGIC No. (%) (pcf) ATTITUDES UNIT ARTIFICIAL FILL-undocumented Afu @ 0-2.5': Silty SAND, brown, dry, loose SM B-1 @ SLOPE WASH Qsw 4'-6' SC @2.5'-9': Clayey SAND, grayish-brown, moist, loose SANTIAGO FORMATION Tsa B-2 @ @9'-12': Silty CLAYSTONE, olive-gray to light brown, moist, medium stiff CL 9'-10' GRAPHICAL REPRESENTATION: SCALE: 1 "=5' SURFACE SLOPE: 0-1°NE TREND: r r-\ J.·I, -~-·t·"--., ··-~·-:-·r-:-i I . ~, , I !• I-. ,, 1 ! f '· / I I · I i' " f . ½ / _/,.. ., _,.f ,,··, ~ ✓-. -./ -/,..•-i. ,• --;;/' . ,. // \(. / _./ / , ./.://; . . \· \~ ,,/· -. . V ~· / Total Depth = 12 Feet ~~:··_ , I 1 / / No Ground Water Encountered ' l / Backfilled: 6/12/14 I J\,, ' . I / I ,. -·· .t I t t 1. I i t J. I .a t t t 1 I a I I I • I 6 I • t tt f • I 1 I 1 I l t il I LOG OF TRENCH: _....,.T.,..-6,..__ __ _ Project Name: Aftoa Way_ Logged by: RV ENGINEERING PROPERTIES Project Number: 10690 002 Elevation-224 feet mean sea level Equipment: Backboe Location/Grid: Soutbem Sample Moisture Density uses GEOLOGIC DATE: 6/12/14 DESCRIPTION: GEOLOGIC No. (%) (pcf) ATTITUDES UNIT ARTIFICIAL FILL-undocumented Afu @0-10': Sandy CLAY, brown to yellowish brown, moist, loose to stiff with CL 8-1 depth; trash 2 6'; asphalt debris at 8' @ 0'-6' SANTlAGO FORMATION Tsa @ 10'-12': Sandy CLAYSTONE, light brown, moist, stiff to very stiff GRAPHICAL REPRESENTATION: SCALE: 1 "=5' SURFACE SLOPE: 5-8°NE TREND: I \ V r"•;-----_,,,."' --... 1·····•, .. ,,, .. , ........... ,,, .. ,,_~--.... . , .. / .. , ·•-•,=ww=• =• .,....,_=~ ././ ,,,,.,,-_. \\ ./ // \/"' \ \ ' Total Depth= 12 Feet \ 1//·"· No Ground Water Encountered ~-Backfilled: 6112/14 >:(,:· :~// GEOTECHNICAL BORING LOG KEY Project No. Project KEY TO BORING LOG GRAPHICS Date Drilled Logged By Drilling Co. Drilling Method Location ci II) ~ C: II) QI 0 .c_ -~ QI z 11).C II) ·--.C Cl "C .!! 3: CJ c:--QI -QI Ill QI a.QI a.o .a o .= QI CJ ~u. ~u. f!..J a. ca. :.:; E mco jjj (!) -~ < Ill ... ti) QI C 0.. N s 0--- ~~::~~=~~- ~ V ,/'.,, ) ) ) s ~~ le .... ..... IO'-'U c 0 (\o a 10 Kl ~tL' 0 0 ~ 0 . . 0 0 IS ~ ~ -,7 -~ -B-1 20-C-l -G-1 0 -R-1 -SH-I -S-1 25 -PUSH - - - - SAMPLiPTYPES: TYPE OF TESTS: B BULK SAMPLE -200 % FINES PASSING C CORE SAMPLE AL ATTERSERG LIMITS G GRAB SAMPLE CN CONSOLIDATION R RING SAMPLE co COLL.APSE s SPLIT SPOON SAMPLE CR CORROSION T TUBE SAMPLE cu UNDl>&INED TRIAXIAL Q)~ .... :::s-.... C: II) QI ·--0 C: ::!!:0 (.) OS El H MD pp RV ui--:--(/)ti) Ill . -(.) (.) . =Cl.! o::::::, rn- CL CH OL ML l\1H ML~CL GW GP GM GC SW SP SM SC Hole Diameter Ground Elevation Sampled By SOIL DESCRIPTION This Soil Description applies only to a location of the exploration at the time of sampling. Subsurface conditions may differ at other locations and may change with time. The description is a simplification of the actual conditions encountered. Transitions between soil types may be gradual. Asphaltic concrete Portland cement concrete Jnorf.anicday of low to medium plasticity; gravelly clay; sandy c ay· silty clay; lean clay Inorganic clay; high plasticity, fat clays Organic clay; medium to plasticity, organic silts Inorganic silt; clayey silt with low plasticity Inorganic silt; diatomaceous fine sandy or silty soils; elastic silt Clayey silt to silty clay Well-graded gravel; gravel-sand mi>..1ure, little or no fines Poorly graded gravel; gravel-sand mixture, little or no fines Silty gravel; gravel-sand-silt mixtures Clayey gravel; gravel-sand-clay mixtures Well-i,>raded sand; gravelly sand. little or no fines Poorly graded sand; gravelly sand, little or no fmes Silty sand; poorly graded sand-silt mixtures Clayey sand; sand-day mixtures Bedrock Grow1d water encmmtered at time of drilling Bulk Sample Core Sample Grab Sample Modified California Sampler (3" O.D., 2.5 J.D.) Shelby Tube Sampler (3" O.D.) Standard Penetration Test SPT (Sampler (2" O.D., 1.4" I.D.) Sampler Penetrates witl10ul Hammer Blow DIRECT SHEAR SA SIEVE ANALYSIS EXPANSION INDEX SE SAND EQUIVALENT HYDROMETER TR THERMAL RESISTIVITY MAXIMUM DENSITY UC UNCONFINED COMPRESSIVE STRENGTH POCKET PENETROMETER RVALUE ***This log is a part of a report by Leighton and should not be used as a stand-alone document *** .!!l II) QI I--0 QI a. >, I- ~ Page 1 of 1 GEOTECHNICAL BORING LOG LD-1 Project No. 10690.002 Date Drilled 7-1-14 Project Afton Way_ Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 274' Location Sampled By FJW/BEV C 0 ·---<11 n, <II >u. .!! w 270 ci Ill >, O)~ Ill <II -.c_ .!:2 <II z ,n.C 'iii ... - .C Cl "C <II ;_:U c,._ ::i--<II _c 0..(11 c..o ::, ii o-= <IIU 11)(11 ~LL. f!..J -cc. ·--:.:; E mco oc (!) -~ c( n, ... :::eo Cl) <II C (.) c.. N s 0 B-l -@,-0-5' - ~4-i-+-~--------------- 5- - R-1 B-2 @5'-8' 7 JI ui--:" SOIL DESCRIPTION IIICI) n, . This Soil Description applies only to a location of the exploration at the -(.) (.) . _Cl) time of sampling. Subsurface conditions may differ at other locations ·o::::i and may change with time. The description is a simplification of the en-actual conditions encountered. Transitions between soil types may be gradual. SM tX)LL!.)VflJM @ 0-3': Silty SAND, reddish brown, dry, loose SJ\1 ,_ VERY OLD PARALIC .DEP()S.lTS (Qvop) @ 3': Silty SAND, reddish brown, dry to moist, medium dense @ 8': Sil1y SAND, reddish brown to orange, dry to moist, medium 265 R-2 -+-+-,-+---1-- - -.13-.3._ ---,__ __ I----1----r--_dense _______________________ ./' 10- B:N40-S(E, @8'-15' ,8SE - 260 15- - -, 255 -· 20- - - - 250 - 25- - -. -· 245 -· JO . SAMP[E TYPES: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RINGSAMPLE · B:N50E, SSE S SPLIT SPCXJN SAMPLE T TUBESAMPLE R-3 10/10" l l I 8 @15'-16 R-4 .12 114 9 B-4 @20'-25 TYPE OF TESTS: -200 % FINES PASSING OS AL ATTERBERG LIMITS El CN CONSOLIDATION H CO COLLAPSE MD CR CORROSION PP CU UNDRAINED TRIAXIAL RV SM TERTIARY SANTIAGO FORMATION (Tsa) @ 9': Silty SAN'DSTONE, pale, olive-gray, moist, medium dense (aJ 15': Silty SANDSTONE with gravel, gray to olive, damp, dense, -fine to medium grained, very little to no bedding @ 20': Silty SANDSTONE with gravel, gray to olive, damp, dense, fine to medmm gramed, very httle to no beddmg @ 24': l/4 inch gypsum layer, horizontal @ 25': Silty SANDSTONE, gray to olive, moist, fme grained sands, dense DIRECT SHEAR EXPANSION INDEX HYDROMETER SA SIEVE ANALYSIS SE SAND EQUIVALENT SG SPECIFIC GRAVITY MAXIMUM DENSITY POCKET PENETROMETER RVALUE UC UNCONFINED COMPRESSIVE STRENGTH * * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * * Ill -Ill <II I--0 <II 0.. >, I- Page 1 of 2 GEOTECHNICAL BORING LOG LD-1 Project No. 10690.002 Date Drilled 7-1-14 Project Afton Way_ Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 274' Location Sampled By FJW/BEV C .!:2 _g_ .c_ -ai -ai .CCJ C'(I Q) 0.ai 0.0 ~LI. ~LI. f!..J w (!) 30 240 235 230 45 225 50 220 55 215 SAMPL,WTYPEs: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RJNG SAMPLE Ill Q) "C ::, -:;:; < S SPLIT SPOON SAMPLE T TUBE SAMPLE ci z G) ii E C'(I t/J R-5 B-5 (qj30'•35 R-6 Ill Q) 11).C ;r:u o.E mc.o ... Q) 0. 25 18 TYPE OF TESTS: ~ Ill c,._ G) u co. ~ C -200 o/o FINES PASSING AL ATTERBERG LIMITS CN CONSOLIDATION CO COLLAPSE CR CORROSION CU UNDRAINED TRIAXIAL Cl)~ .... ::s--c Ill Gl ·--oc ::!!0 (.) ui--:-SOIL DESCRIPTION 1/lt/J C'(I • This Soil Description applies only to a location of the exploration at the -(.) (.) . ::~ time of sampling. Subsurface conditions may differ at other locations and may change with time. The description is a simplification of the o::::, ttJ-actual conditions encountered. Transitions bell/Ileen soil types may be gradual. CL @ 30': Sandy CLAYSTONE, gray, dry to moist, hard @ 30': Grades to silty SANDSTONE CL-SM @ 30': Contact between SANDSTONE and CLA YSTONE, horizontal @ 33'-34': Contact between CLAYSTONE and SANDSTONE, horizontal SC-SM @ 40': Silty to clayey SAND, gray to olive, dry to moist, medium grained Geologically Logged = 40.5 Feet Total Depth = 43.5 Feet No groundwater encountered at time of drilling Bacldillcd with bentonite and soil on 7/1/14 DS DIRECT SHEAR SA SIEVE ANALYSIS SE SAND EQUIVALENT SG SPECIFIC GRAVITY El EXPANSION INDEX H HYDROMETER MD MAXIMUM DENSITY PP POCKET PENETROMETER RV RVALUE UC UNCONFINED COMPRESSIVE STRENGTH * * * This log is a part of a report by Leighton and should not be used as a stand-alone document * * * Ill -Ill Q) I-... 0 (I) 0. >, I- Page 2 of 2 GEOTECHNICAL BORING LOG LD-2 Project No. 10690.002 Date Drilled 7-1-14 Project Afton Way_ Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 263' Location Sampled By FJW/BEV C: 0 ·---Cl) lllci, ~LL. jjj 260 255 .!:1 .c_ .c C) -Cl) Q.CI) c.o ~LL. E!..J c., ci II) Cl) z "C Cl) .a Q. :.:; E -< Ill en Ill s 0 - - ---+-'4------<----+-----i ------ 5- - - fR·N30\' ·90 .. ' R-l B-l @51-10' II) Cl) 11).C ;,: CJ o-= jjiw ~ Cl) c.. 10 >, SOIL DESCRIPTION Q)~ ui-:-~ II) ~ -ll)U, c:,._ ::,-Ill • This Soil Description applies only to a location of the exploration at the Cl) CJ .. c: -u ca. ll)CI) (.). time of sampling. Subsurface conditions may differ at other locations ·--_en 0 C: ~ ·c5::; and may change with time. The description is a simplification of the :ED C (.) en-actual conditions encountered. Transitions between soil types may be gradual. SM COLL]JVJVM @ 0-3': Silty SAND, reddish bro,\11, dry, loose S\1 -VERY QLD PAR.ALIC .DEP()S.lTS (Qvop) @ 3': Silty SAND, reddish-bro\\11, dry to damp, medium dense l 15 8 @ 5': Silty SAND, light brown, damp, mediW11 dense 10 ---R.-2 -12-f--126 --9-SM >--TERTLAAYSANTIAGOFORMATION(Tsa) - - 250 - - 15- - - 245 - -· 20-·. - - 240 - 25- - 235 -. SAMPL~TYPES: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RING SAMPLE S SPLIT SPOON SAMPLE T TUBE SAMPLE R-3 I JO/I()" 129 TYPE OF TESTS: -200 % FINES PASSING AL ATTERBERG LIMITS CN CONSOLIDATION CO COLLAPSE CR CORROSION CU UNDRAINED TRIAXIAL @ I 0': Silty SANDSTONE, light bro\\11, moist, mediw11 dense to dense, massive 8 SM @ 20': Silty SANDSTONE, light brown, moist, dense, massive DS DIRECT SHEAR El EXPANSION INDEX H HYDROMETER MD MAXIMUM DENSITY PP POCKET PENETROMETER RV RVALUE SA SIEVE ANALYSIS SE SAND EQUIVALENT SG SPECIFIC GRAVITY UC UNCONFINED COMPRESSIVE STRENGTH * * * This log is a part of a report by Leighton and should not be used as a stand-alone document * * * II) -II) Cl) I-.... 0 Cl) Q. >, I- Page 1 of 2 GEOTECHNICAL BORING LOG LD-2 Project No. 10690.002 Date Drilled 7-1-14 Project Afton Way Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 263' Location Sampled By FJW/BEV ci C/) ~ SOIL DESCRIPTION C/) ca,~ ui--:---C: C/) QI C/) 0 .r._ -~ QI z C/).r. C/) '--C/)(1) QI ·--.r. Cl 'C ..9:! 3: u c:-:::i-111· This Soil Description applies only to a location of the exploration at the I--QI -QI _ c: -u 111 QI a.QI a.o .a o.E QI u C/) QI (.) . ->u. ~u. E..J a. ca. ·--_(/) time of sampling. Subsurface conditions may differ at other locations 0 :.:; E mco 0 C: ..9:! (!) -~ ·o::i and may change with time. The description is a simplification of the QI w <( 111 ... :::!EO a. (/) QI C (.) (I)-actual conditions encountered. Transitions between soil types may be >, D.. gradual. I- Ill !, 30 R-4 29 SM ({i), 30': Silty SANDSTONE, light bro'wn, moist, dense, massive - -. 230 -. - 35-Geoloy;cally loJf ed to 30.5 Feet Total epth = : .5 Feet -No tnjndwater encountered at time of drilling Bae ed with bentonite and soil on 7/1/14 - 225 - - 40- - - 220 - - 45- - - 215 - - 50- - - 210 - - 55- - - 205 - - SAMPLi6TYPES: TYPE OF TESTS: B BULK SAMPLE -200 °lo FINES PASSING OS DIRECT SHEAR SA SIEVE ANALYSIS C CORE SAMPLE AL ATTERBERG LIMITS El EXPANSION INDEX SE SAND EQUIVALENT G GRAB SAMPLE CN CONSOLIDATION H HYDROMETER SG SPECIFIC GRAVITY R RING SAMPLE co COLLAPSE MD MAXIMUM DENSITY UC UNCONFINED COMPRESSIVE STRENGTH S SPLIT SPOON SAMPLE CR CORROSION pp POCKETPENETROMETER T TUBE SAMPLE cu UNDRAINED TRIAXIAL RV RVALUE * * * This log is a part of a report by Leighton and should not be used as a stand-alone document * * * Page 2 of 2 GEOTECHNICAL BORING LOG LD-3 Project No. 10690.002 Date Drilled 6-30-14 Project Afton Way_ Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 264' Location Sampled By FJW/BEV Cl) >, SOIL DESCRIPTION Cl) ci (J)~ ui-:---c:: Cl) 0, ~ Cl) 0 .c_ -~ 0, z Cl).C Cl) '--Cll(/) 0, ·--.Cc, "C 0, :it u c::-:::,-cg . This Soil Description applies only to a location of the exploration at the I--o, -o, _c:: -u cg 0, O.o, c.o :::, a. o.f: 0, u C/)0) (.) . time of sampling. Subsurface conditions may differ at other locations -~LL ~LL f!..J -cc. ·--_Cl) 0 :;; E ffico oc:: (!) -~ ·c5::; and may change with time. The description is a simplification of the 0, w < cg '-:EC C. Cl) 0, C (.) cn-actual conditions encountered. Transitions between soil types may be >, 0.. gradual. I-N s 0 SM ARTIFI(;LA..L FILL-undocumented (Afi.t) -(ill, 0-2': Silty SAND, brown, dry, loose @0-5': Fill, roots to rootlets -@ 2"-5': Silty SAND, light brown, moist, medium dense - 260 - 5 -----1---------r--R.-1 6 107 2 SM -Ol 'ATERNARY SLOPE WASH fOsw) -B-1 @ 5': Silty SAND, orange-brown, dry, medium dense, porous, @j,5'-10' loose, roots and rootlets 3-9% orgaitics - - 255 - 10 1---------f--------------------------------B:N3o-=-sc E R-2 10 118 7 SM TERTIARY SANTIAGO FORMATJQN (Tsa) ' -· JOSE @ I 0': Silty SANDSTONE, light bro~n, damp, medium dense - -@ l 3'-18': Manganese staining vertical 250 - 15-R-3 I0/10" 124 8 @ 15': Silty SAND. light brown, moist, medium dense to dense - - -B-2 245 -· @l8'20' 20-·. R.4 11 124 9 @ 20': Silty SAND, light brown, moist, medium dense to dense - - - 240 - 25-. B:N55E, R-5 20 J 14 13 @25': Sandy SILTSTONE, olive-gray, moist, hard -JOSE @ 26': Silty SANDSTONE over sandy SILTSTONE - - 235 -· SAMPL1TYPES: TYPE OF TESTS: ~ B BULK SAMPLE -200 % FINES PASSING DS DIRECT SHEAR SA SIEVE NW. YSIS C CORE SAMPLE AL ATTERBERG LIMITS El EXPANSION INDEX SE SAND EQUIVALENT G GRAB SAMPLE CN CONSOLIDATION H HYDROMETER SG SPECIAC GRAVITY R RING SAMPLE co COLL.APSE MD MAXIMUM DENSITY UC UNCONFINED COMPRESSIVE STRENGTH s SPLIT SPOON SAMPLE CR CORROSION pp POCKETPENETROMETER T TUBE SAMPLE cu UNDRAINED TRIAXIAL RV RVALUE ***This log is a part of a report by Leighton and should not be used as a stand-alone document * * * Page 1 of 2 GEOTECHNICAL BORING LOG LD-3 Project No. 10690.002 Date Drilled 6-30-14 Project Afton Way_ Logged By FJW Drilling Co. Alro Hole Diameter 26" Drilling Method Bucket Auger -0-24=2,400lb Ground Elevation 264' Location Sampled By FJW/BEV C -~ Ill 0 .c_ Cl) ·--.C Cl 't:J -Cl) -Cl) n, Cl) a.Cl) a.o ::, >1.1. ~LI. e!..J -; ~ (!) ~ w N s 30 - -+,..+,--r,...,.....,.--,--- - 230 - 35- - -+...L...-j=-1,,,,.j---vvvv 225 -vvv V v ci z Cl) Q. E n, Cl) R-6 Ill Cl) 11).C ~ (J o.E iij<D ... Cl) a. 27 >, ~ Ill c-CII IJ ca. ~ C Q)~ ... -::,-.... c 1/lCII ·--cc :EC (.) ---f---I--- ui---:-1/lCI) co . -(.) (.) . ==~ c::::::, Cl)- SOIL DESCRIPTION This Soil Description applies only to a location of the exploration at the time of sampling. Subsurface conditions may differ at other locations and may change with time. The description is a simplification of the actual conditions encountered. Transitions betvveen soil types may be gradual. SM-ML W O': Clayey SANDSTONE, light olive-gray, moist. dense ,a). 30': Sandy SILTSTONE, gray, mmst, iknse @ 30'-32': Clayey SANDSTONE, sandy SILTSTONE, gray, moist. __ ,-___dense _______________________ _.,. CL @ 32': CLA YSTONE, laminated, polished surfitces, discontinuous, hard @ 35': Grades into CLA YSTONE, olive-gray, moist, hard Si\-1 -@ 361: Grades into silty SANDSTONE, olive-gray, mojst, dense SM-CL f-@ 38': fntcrbedded CLA YSTONE and SANDSTONE 40 --+-.....--,...._,..._._ -- - - --29-~ --~ ---SM ~ @ 40': Silty SANDSTONE, gray, moist, ve1y dense, friable - -. -. 220 - 45- - - -. 215 -· so-·. - - 210 - 55- - - - 205 SAMPL'iPTYPEs: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RING SAMPLE S SPLIT SPOON SAMPLE T TUBE SAMPLE R-7 R-8 50/10" TYPE OF TESTS: -200 o/a FINES PASSING AL ATTERBERG LIMITS CN CONSOLIDATION CO COLLAPSE CR CORROSION CU UNDRAINED TRIAXIAL SM @ 50': Silty SANDSTONE, gray, moist, very dense, friable Geologically Logged = 48 Feet Total Depth = 51 Feet No groundwater encountered at time of drilling Backfilled with hentonite and soil on 6/30/14 OS DIRECT SHEAR El EXPANSION INDEX H HYDROMETER MD MAXIMUM DENSITY PP POCKET PENETROMETER RV RVALUE SA SIEVE ANALYSIS SE SAND EQUIVALENT SG SPECIAC GRAVITY UC UNCONFINED COMPRESSIVE STRENGTH * * * This log is a part of a report by Leighton and should not be used as a stand-alone document*** !l Ill ~ 0 Cl) a. >, ... Page 2 of 2 Appendix C Laboratory Testing Procedures and Test Results Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 APPENDIX C Laboratory Testing Procedures and Test Results Moisture Tests: Moisture content determinations were performed on disturbed samples obtained from the test borings. The results of these tests are presented in the boring logs. Atterberg Limits: The Atterberg Limits were determined in accordance with ASTM Test Method D4318 for engineering classification of the fine-grained materials and presented in the table below: Liquid Limit Plastic Limit Plasticity Index uses Soil Sample Location (%) (%) (%) Classification B-1 at 30 to 35 45 18 27 CL feet Particle Size Analysis (ASTM D6913): Particle size analysis was performed by mechanical sieving methods according to ASTM D6913. Plots of the sieve results are provided on the Figures in this appendix. Direct Shear Tests: A direct shear test (ASTM D 3080) was performed on selected sample which was soaked for a minimum of 24 hours under a surcharge equal to the applied normal force during testing. After transfer of the sample to the shear box and reloading of the sample, the pore pressures set up in the sample (due to the transfer) were allowed to dissipate for a period of approximately 1-hour prior to application of shearing force. The samples were tested under various normal loads utilizing a motor- driven, strain-controlled, direct-shear testing apparatus at a strain rate of 0.0025 inches per minute. After a shear strain of 0.2 inches, the motor was stopped and the sample was allowed to "relax" for approximately 15 minutes. The stress drop during the relaxation period was recorded. It is anticipated that, in a majority of samples tested, the 15 minutes relaxing of the samples is sufficient to allow dissipation of pore pressures that may have set up in the samples due to shearing. The drained peak strength was estimated by deducting the shear force reduction during the relaxation period from the peak shear values. The shear values at the end of shearing are considered to be ultimate values and are presented on the attached figure. The samples were either remolded to 90% relative compaction, undisturbed, or the samples were tested in a torsional shear machine to C-1 Geotechnical Investigation, 2200 Afton Way, Carlsbad, California 10690.002 APPENDIX C (Continued) evaluate the remolded clay seam properties. The test results are provided on the Figures in this appendix. Chloride Content: Chloride content was tested in accordance with Caltrans Test Method CT 422. The results are presented below: Sample Location Sample Description Chloride Content (ppm) T-1 @ 0.0-4.0 Brown Silty Sand 62.3 feet Minimum Resistivity and pH Tests: Minimum resistivity and pH tests were performed in general accordance with California Test Method 643. The results are presented in the table below: Sample Location pH Minimum Resistivity (ohms-cm) T-1 @ 0.0-4.0 feet 7.19 8,240 Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods (Caltrans Test Method CT417). The test results are presented in the table below: Sample Location Sample Description Sulfate Potential Degree Content(%) of Sulfate Attack* T-1 @0.0 to 4.0 Brown Silty Sand <0.015 Negligible feet * Based on the 2005 edition of American Concrete Institute (ACI) Committee 318R, Table No. 4.3.1. C-2 Geotechnical Investigation, 2200 Afton Way. Carlsbad, California 10690.002 APPENDIX C (Continued) Expansion Index Tests: The expansion potential of selected materials was evaluated by the Expansion Index Text, ASTM Test Method 4829. A specimen is molded under a given compactive energy to approximately 50 percent saturation. The prepared 1-inch thick by 4-inch diameter specimen is loaded to an equivalent 144 psf surcharge and is inundated with water until volumetric equilibrium is reached. The result of this test is presented in the table below: Sample Location Description Expansion Expansion Index Potential TP-3@0.5 to Brown Clayey Sand 53 Medium 3.0 feet C-3 !;XRl5 I I CD:~[ I COARSE I ~RI:~ I FINE MEDIUM I FINE SILT I Q.AY U.S. STANDARD SIEVf OPENING U.S. STANDAAD SIM NUMBER HYDROMETER 3.o· 111r 3W 3/8. I◄ 18 #16 130 ISO 1100 1200 100 ----,--~ ---~ 90 ' \ 80 ' 70 ' \ 60 \ j I 50 \ \ 40 ~ '~ '-30 -......... ... ,..le 0.. i 20 0 w t-10 ~ e I m 0 ~ 100.000 10.000 1.000 0.100 0.010 0.001 IU e PARTICLE -SIZE (mm) % ... Project Name: AFTON WAY Project No.: 10690aQQZ Exploration No.: 8:.1 Sample No.: B:J Depth (feet): 8,D-1.5,D Soll Type: SM -PARTICLE -SIZE tlf Leighton Soil Identification: SM: SILJY SAND, Grayjsh-Yenow DISTRIBUTION ASTM D6913 GR:SA:FI: (~) 0 . 75: 25 JUl-1'+ . I "R~~ I co:~ I COARSE! SANr5 I FINE MmnJM I FIN£ SILT I Q.AY U.S. STANDARD SIEV£ OP£NING U.S. STANCWtD SIEVE~ HYDROMETER 3.o· 111r 314• 3/8" #4 #8 #16 #30 ISO #100 #200 100 -----,--,-------~ 90 ~ ......... r--.... "-1 ............. ........ -80 -............. .... 70 60 50 40 30 CL I 20 (.) w 1-10 I&. I! I m 0 3 100.000 10.000 1.000 0.100 0.010 0.001 w PARTICLE · SIZE (mm) e ::z: I-Project Name: AFTON WAY Exploration No.: B:1 Sample No.: B:S Project No.: 10690.QQZ Depth (feet): 3Q,Q-3S,Q Soil Type: (CJ.\ -PARTICLE -SIZE t/1 Leighton Soff ldenttflcation: (a,}s: LEAN Q,AY WITH SANO, Yellowish-Brown DISTRIBUTION ASTM D6913 GR:SA:FI: (~} 0 . 21: 74 Ju1-1q . I ~~[ I COARSE I SANr5 I J!!RI:~ I FINE MEDIUM I FINE SILT I a.AV U.S. STANDARD SIM OPENING U.S. STANDARD SIM MJMl!Bl HYDROMETER 3.0" 11/T 314• 3/r #4 #8 #16 #30 #50 #100 #200 100 ---------' 90 '\ \ 80 \ 70 ' 60 ' 50 i\ \ 40 \. . ---,---\ \ 30 " A. '-I 20 " 0 'r--w • t-10 "' • I m 0 ~ 100.000 10.000 1.000 0.100 0.010 0.001 w PARTICLE • SIZE (mm) e % ... Project Name: AFTON WAY Exploration No.: I:S Sample No.: .6:1 Project No.: 10690.00Z Depth (feet): 1,ll:6,C Soil Type: SC ct Leighton PARTICLE -SIZE Soil Identification: SC; CLAVEY SAND, Grayish-Brown DISTRIBUTION ASTM D6913 GR:SA:FI : (tM.) 0 . 15: 15 Jun-1<t . I ~~ I OOMSE I SANO I "Al:!; I FINE MEDIUM I FM SILT I a.AV U.S. STANDARD SIEVE OPENING U.S. STANDMD SIEVE NUMIIER ~R J.o· 11rr 3/~· 3~ ,~ Ill 116 130 ,so 1100 1200 100 ----. . . -~ -~ ---.... ~I'-'N ~ 90 ...... ,.,......._ ~ ~19 80 70 60 50 4'0 30 A. I 20 CJ I .,_ 10 IL .: I m 0 ~ 100.000 10.000 1.000 0.100 0.010 0.001 w PARTICLE -SIZE (mm) e ::z: ... Project Name: AFTON WAY Exploration No.: li Sample No.: 8:1 Project No.: 10690.002 Depth {feet): 12.12:::6.D Soff Type: s(W -PARTICLE -SIZE t/1 Leighton Soil Identification: sCW; SNl>Y LEAN WY. YefkMisb-Bmwo DISTRIBUTION ASTMD6913 GR:SA:FI : (~) 1 . 15: 14 Jun-1q . ~ 4.00 -t-------~.,....._____,f----------+-----------f ~ It) j 3.00 +--+-------'l~--------+--------i J 2.00 T""t--.::::;:---------t-------;-------- 1.00 0.00 _______ ____, _______________ ..... 0 0.1 0.2 0.3 Horizontal Deformation (in.) 5.0 ,------,---..-----r---.....---. 0.0 ------------------1 0.0 1.0 2.0 3.0 4.0 5.0 Normal StrMI (ksf) B-1 Normal Stress (kip/ft2) 1.000 2.000 4.000 R-5 Peak Shear Stress {kip/ft2) • 1.270 ■ 1.943 A4.769 30-31 Shear Stress O End d Test (ksf) o 1.236 D 1.311 A 2.405 RING Deformation Rate (in./mln.} 0.0017 0.0017 0.0017 Soil Identification: Initial Sample Height {In.) 1.000 1.000 1.000 CL: LEAN CLAY'STONE', Olive Diameter (in.) 2.◄15 2.◄15 2.◄15 InltNtl Moisture Content (%) 10.16 10.16 10.16 Dry Density (pcf) 111.6 11◄.6 120.5 C Saturation(%) 53.7 58.3 68.8 Peak -143.0 50.2 Soil Height Before Shearing (in.) 0.9958 0.9845 0.9848 Ultimate 689.0 22.4 Final Moisture Content (%) 22.3 20.0 18.1 • Project No.: 10690.002 fll Leighton DIRECT SHEAR TEST RESULTS Conaolldatecl Drained -ASTM D 3080 AFTON WAY 07-1◄ ~ 2.00 +----.f----------,f---~------+----------1 ~ .,, j 1.50 -----------,f-----------+--------t j 1.00 -t-f'-r-------.i:a::;;;::------t-----------1 "' 0.00 -------------le----------+----------1 0 0.1 0.2 0.3 B-1 No. R-2 ft 10-11 Sample IYPC; RING Soff Idcfji(jgrtion: SC: CLAYEY SANO'STONE', Pale Olive Peak 185.0 51 .2 Ultimate 112.0 38.2 Horizontal Deformation (in.) 4.0 ....----.....------------. I ---3.0 _______ _,_ ______ L----1 --,, -· ,, 0.0 +-----+----+-----+--~ 0.0 1.0 2.0 Normal S11911 (kif) Normal Stress (klo/ft2) Peak Shear Stress (kip/ft2) 3.0 Shear Stress O End cl Test (ksf) Deformation Rate (ln./min.) Initial Sample Height (In.) Diameter (In.) Initial Moisture Content(%) Ory Density (pd) Saturation(%) Soil Height Before Shearing (In.) Final Moisture Content(%) 4.0 0.500 • 0.858 o 0.538 0.0025 1.000 2.◄15 8.19 113.1 ◄5.1 0.9982 16.5 1.000 2.000 ■ 1.355 .A 2.701 D 0.852 61.704 0.0025 0.0025 1.000 1.000 2.415 2.◄15 8.19 8.19 115.3 11◄.5 47.9 ◄6.9 0.9942 0.9886 15.6 15.2 ~ tlJI Leighton Project No.: 10690.002 DIRECT SHEAR TEST RESULTS Consolidated Drained • ASTM D 3080 AFTON WAY 07-14 - .. .. .. .. -... -Appendix D General Earthwork and Grading Specifications for Rough Grading .. .. -,.. .. .. .. -.. .. • .. .. ... -.. .. .. ... .... - - - - - .. .. .. .. .. .. - --.. .. .. -- LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications 1.0 General 1.1 Intent 1.2 These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnical report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the recommendations in the geotechnical report(s). The Geotechnical Consultant of Record Prior to commencement of work, the owner shall employ the Geotechnical Consultant of Record (Geotechnical Consultant). The Geotechnical Consultants shall be responsible for reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencement of the grading . Prior to commencement of grading, the Geotechnical Consultant shall review the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to perform the appropriate level of observation, mapping, and compaction testing . During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required. Subsurface areas to be geotechnically observed, mapped, elevations recorded, and/or tested include natural ground after it has been cleared for receiving fill but before fill is placed, bottoms of all "remedial removal" areas, all key bottoms, and benches made on sloping ground to receive fill . The Geotechnical Consultant shall observe the moisture-conditioning and processing of the subgrade and fill materials and perform relative compaction testing of fill to determine the attained level of compaction . The Geotechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis. -1- -... - - - - - - - -... -... --- -.. - .. - --- LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications 1.3 The Earthwork Contractor The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moisture-conditioning and processing of fill, and compacting fill. The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for performing the grading in accordance with the plans and specifications. The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of "spreads" of work and the estimated quantities of daily earthwork contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate observations and tests can be planned and accomplished. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations. The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified. 2.0 Preparation of Areas to be Filled 2.1 Clearing and Grubbing Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant. -2- - -.. ... - ----- .... -... - - - - -.. .. .. .. .. ... -.. -.. -- LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). No fill lift shall contain more than 5 percent of organic matter. Nesting of the organic materials shall not be allowed. If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to continuing to work in that area. As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be allowed. 2.2 Processing Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until soils are broken down and free of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction. 2.3 Overexcavation In addition to removals and overexcavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be overexcavated to competent ground as evaluated by the Geotechnical Consultant during grading . 2.4 Benching Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical -3- -... ... - .... ---... --- --.. • -.. - ---.... - -.. -.. - - - - LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications Consultant. Fill placed on ground sloping flatter than 5: 1 shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill. 2.5 Evaluation/Acceptance of Fill Areas All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches. 3.0 Fill Material 3.1 General Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soils to achieve satisfactory fill material. 3.2 Oversize Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction. 3.3 Import If importing of fill material is required for grading, proposed import material shall meet the requirements of Section 3.1. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed. -4- ... - - ------- - ---... .. --- ... ... ... - -.. ---.. LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications 4.0 Fill Placement and Compaction 4.1 Fill Layers Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout. 4.2 Fill Moisture Conditioning Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557). 4.3 Compaction of Fill After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test Method D1557). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity. 4.4 Compaction of Fill Slopes In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D1557 . 4.5 Compaction Testing Field-tests for moisture content and relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to -5- - - - -... -... --- -- -... -.. -... .. -... -.. .. LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications inadequate compaction (such as close to slope faces and at the fill/bedrock benches). 4.6 Frequency of Compaction Testing 4.7 Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met. Compaction Test Locations The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 5 feet apart from potential test locations shall be provided. 5.0 Subdrain Installation Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys. 6.0 Excavation Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only. The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant. -6- .. ... -.. -.. - .. • .. .. .. - -.. ---... ... --- "" - - -- LEIGHTON AND ASSOCIATES, INC. General Earthwork and Grading Specifications 7 .0 Trench Backfills 7.1 Safety The Contractor shall follow all OSHA and Cal/OSHA requirements for safety of trench excavations. 7 .2 Bedding and Backfill All bedding and backfill of utility trenches shall be performed in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over the top of the conduit and densified. Backfill shall be placed and densified to a minimum of 90 percent of relative compaction from 1 foot above the top of the conduit to the surface . The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill. 7 .3 Lift Thickness Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method. 7.4 Observation and Testing The densification of the bedding around the conduits shall be observed by the Geotechnical Consultant. -7- FILL SLOPE PROJECTED PLANE 1: 1 (HORIZONTAL: VERTICAL) MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND ALL-OVER-CUT SLOPE PAC TED:-:-:-::. -'ff -.-.·-·.:..-:f:..:..:C EXISTING .-::::-·· GROUND SURFAC.E ') -' ,,....,_~ !!~·' BENCH HEIGHT /----( 4 FEET TYPICAL) ----·----------~CMll'i:::. ,,..,, __,,, -----,15 FEET MIN., __,,, __,,, -" LOWEST ..-2. FEET BENCH (KEY) -m!ffe'~T~EY CUT FACE REMOVE UNSUITABLE MATERIAL SHALL BE CONSTRUCTED PRIOR TO / _,, Fill PLACEMENT TO ALLOW VIEWING /'/ OF GEOLOGIC CONDITIONS /' / // EXISTING / CUT--OVER-FLL SLOPE GROUND SURFACE _---.- UT FACE SHALL BE CONSTRUCTED PRIOR TO FILL PLACEMENT PROJECTED PLANE 1 TO 1 MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND OVERBUILD AND...----"'% TRIM BACK ---.....=:r..-. REMOVE DESIGN SLOPE--,,:,£X UNSUITABLE MATERIAL LBENCH HEIGHT ( 4 FEET TYPICAL) 115 FEET MIN.1 BENCHING SHALL BE DONE WHEN SLOPE'S 2 FEET MIN. ' LOWEST ' ANGLE IS EQUAL TO OR GREATER THAN 5: 1. KEY DEPTH BENCH (KEY) MINIMUM BENCH HEIGHT SHALL BE 4 FEET AND MINIMUM Fill WIDTH SHALL BE 9 FEET. KEYING AND BENCHING GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAI L A F\NISH GRADE --------·--------· .. .., ................. ... SLOPE FACE OVERSIZE WINDROW • OVERSIZE ROCK IS LARGER THAN 8 INCHES IN LARGEST DIMENSION. • EXCAVATE A TRENCH IN THE COMPACTED FILL DEEP ENOUGH TO BURY ALL THE ROCK. • BACKFILL WITH GRANULAR SOIL JETTED OR FLOODED IN PLACE TO FILL All THE VOIDS. • 00 NOT BURY ROCK WITHIN 10 FEET OF FINISH GRADE. • WINDROW OF BURIED ROCK SHALL BE PARALLEL TO THE FINISHED SLOPE. GRANULAR MATERIAL TO BE DENSIFIED IN PLACE BY FLOODING OR JETTING. DETAIL JETTED OR FLOODED ----- GRANULAR MA TERI AL TYPICAL PROFILE ALONG WINDROW OVERSIZE ROCK DISPOSAL GENERAL EARTHWORK AND GRADING SPECI FICATIONS STANDARD DETAIL B BENCHING CALTRANS CLASS 2 PERMEABLE 6 .. MIN. OVERLAP FILTER FABRIC (MIRAFI 140N OR APPROVED EQUIVALENT)• OR #2 ROCK (9Fr3/FT) WRAP • • IN FILTER FABRIC • : • . . . . . . . . .~ IJI /s ,. --.:'-a..i 4" MIN. BEDDING t COLLECTOR PIPE SHALL BE MINIMUM 6 .. DIAMETER SCHEDULE 40 PVC PERFORATED PIPE. SEE STANDARD DETAIL D FOR PIPE SPEC!FICA Tl0NS SUBPRAIN DETAIL DESIGN FINISH GRADE .., __ ,.. .. ____ _ __ ._._:_:_:_:_:_:_:_:_:_:_:_ 10' MIN, --, ------• ----• -• BACKFILL -:::::~: -.-:•:COMP,\CT£0: FILL:.:~:.-:-:-:-:-.:~. FILTER FABRIC (M!RAFI 140N OR APPROVED EQUIVALENT) :·:::::::::::::::··-· •.. -. . • ." • • . • ." • • · • --CALTRANS CLASS 2 PERMEABLE .-.-.---.·-·-·-· • • •. • ·• • •• ; : :· • • • •. •. : • •• OR 12 ROCK (9Fr3/f"T) WRAPPED I-• • • . • . IN FILTER F ASRIC I 20' MIN. 5· MIN. I PERFORATED · • • 6" 0 MIN. PIPE NONPERFORATED 6 .. 0 MIN. DETAIL PE CANYON SUBPRAIN OUTLET CANYON SUBDRAINS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAIL C OUTLET PIPES 4" 0 NONPERFORATED PIPE. 1 oo· MAX. o.c. HORIZON TALLY. 30' MAX 0.C. VERTICALLY 15' MIN. TRENCH _-:=:=:=:=:=:=:=:=:=: {:::::::: -:=:=:=::: :: ·:://·: .-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:::-:-:-:-:•I .-:::::::::::t<5flPAC1'1:".0-riLl.:•::::::::::::-" . - ----············--------·-····/=-.l_ cj.::. LOWEST SUBDRAIN SHOULD BE SITUATED AS LOW AS POSSIBLE TO ALLOW SUITABLE OUiLET -...................... -............ -... ----.... -..... _ .. _ .. _ .. _ ..................... ._-_ .. _ -_-_-_ .. _-,. ... . . .--::::::::::::::::::::::::::::~2% !-4IN .•::::::::::::::::::::_::·--r · -'--mrri711!!5":··-.. -.~--.. -....... · ... -.. · ... -.. · ... --· ... ---------.. -.w ............... _-.... _.._ ... _ .. _ .. _ .. _ .. _ :-:-:-:-:-:-:-:-:-:-:-:-2~ MIN.-:-:-:-:-:-:-:-:-:-:-:-:•:•:•· -r--r·::···:~:::·~y G~~~:,~::::.·.' LKEY DEP TH (15' MIN) 1 r MIN. OVERLAP FROM THE TOP HOG RING TIED EVERY (2' MIN.) . 6 FEET T-CONNECTION FOR COLLEC TOR CAL TRANS CLASS II PERMEABLE OR 112 ROCK (3 FTA3/FT) WRAPPED IN FILTER PIPE TO OUTLET PtPE 6" MIN. FABRIC COVER 4" 0 ON-PERFORATED UTLET •~ -;;:::--::::::;:.-::;§:.£.'.:: 4"0 PERFORATED PIPE ----. ~--4" MIN. PROVIDE POSITIVE FILTER FABRIC SE AL AT THE ENVELOPE (MIRAFI JOINT 140 OR APPROVED EQUIVALENT) SUBDRAIN lRENCH DETAIL BEDDING SUBDRAIN INSTALLATION -subdrain collector pipe sholl be installed with perforation down or. unless otherwise designoted by the geotechnicol consultant. Outlet pipes shall be non-perforated pipe. The subdroin pipe shall hove at least 8 per·forations uniformly spaced per foot. Perforation shall be 1/4" to 1/2" if drill holes ore used. All subdroin pipes shall hove o gradient of ot leos I 27. to words the ou tlel. SUBDRAIN PIPE -Subdroin pipe slloll be ASTM D2751, SOR 23.5 or ASTM D1527. Schedule 40, or ASTM 0.3034, SOR 2.3.5. Schedule 40 Folyvin)i Chloride Plastic (PVC) p)pe. All outlet pipe shall be pieced in a trench no wider than twice the subdrain pipe. BUTTRESS OR REPLACEMENT FILL SUBDRAINS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAIL D CUT-FILL TRANSITION LOT OVEREXCAVATlON --------- REMOVE UNSUITABLE GROUND \_ ..--_ ---------- -----------5' --------------------------· -.----=== -------COMPACTED Ff!± ---_ _.,. ------·--,,,,z>-->;~~,,..;,a,.__;c:_~~...l<C:l->:::::.:1..4--~~ . -------------------------------------~---_-_-_:,.-----::=_-_-_-_-_-_-..,;:::.,..:-:..-_-_-_ ·•··· -. ..... .... ·-· ··-· .... ..,,,,. "=-~=-r-......-,;,-,,---' ~--------------------::_::-' ,<.~1/' . ---? ..:-:_ --~ TYPICAL <~1/' BENCHING OVEREXCAVA TE AND RECOMPACT UNWEATHERED BEDROCK OR MATERIAL APPROVED ,----· --- .... -... ~ BY THE GEOTECHNICAL CONSUL TANT~------ TRANSITION LOT FILLS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAIL E RETAINING WALL WALL WATERPROOFING ~ PER ARCHITECT'S SPECIFICATlONS f'INISH GRADE SOIL BACKFILL, COMPACTED TO 90 PERCENT RELATIVE COMPACTION BASED ON ASTI-A D1557 ------------~ -*-· -~ ~---~-----··········-- ;:;:;:;:;:;:::::;:;:;:;:;:; ; ;: : ;~~;;:;:;:;;.:. -. -----·----~---· --------- 1 I 6" Ml~• I.I =~:~:~:~:~=~=t::~:--1' OVERLA.P I=:=:=:=:=:=:=·· FILTER F'ASRIC ENVELOPE • o• :::::::-:-·. (MIRAf'I 140N OR APPROVED lo O o • 0 1 =:::::{ EQUIVALENT) .. 0 _,..,. .... • • 0 0 :=:=:=:=: I~~· ~IN ... l ~.3/4" TO 1-1/2" CLEAN GRAVE.l I· .0 ~-===::_: o , • • •• ::::::; _ ___......-4" (MIN.) DIAMETER PERFORATED l, 0 ,-:~ PVC PIPE (SCHEDULE 40 OR I • o0 ' :::::::~ EQUIVALENT) WITH PERFORATIONS 0 -:-:-:-:• ORIENTED DOWN AS DEPICTED I I::::::::: MINIMUM 1 PERCENT GRADIENT ~ ::::::::: TO SUITABLE OUTLET L -• ·:·:·:•:• J" MIN. COMPETENT BEDROCK OR MATERIAL AS EVALUATED BY THE GEOTECHNICAL CONSULTANT NOT£; UPON REVIEW BY THE GEOTECHNICAL CONSUL TANT. COMPOSITE DRAINAGE PRODUCTS SUCH AS M!RADRAIN OR J-DRAIN MAY BE USED AS AN ALTERNATIVE TO GRAVEL OR CLASS 2 PERMEABLE MATERIAL. INSTALLATION SHOULD BE PERFORMED IN ACCORDANCE WITH MANUFACTURER'S SPECIFICATIONS. RETAINING WALL DRAINAGE GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAIL F FILTER FABRIC ~--,r._:lf ::•i[rn j:L111~[~• ___ ,,.-§',!. : : : REINFORCED •;::::.;;: ·•:: RETAINED /· _.· ZONE ~ , ' , ~ ' , , ;~: > , < .~ >' • : ·: ~' : . • ' . : "~' , , ; ., : . ' , ,. ' ,. ' , ~ ' , > ' , ' , , ' , ,. ~ , , .• , ' < , .. , ' ' , ~ ' , ' I I , ; ' V ; < , ' , ' , ' ,.. , ., , ' , 'f'"1J " ,-.,7;~"""'--::--:-:---7°•~;""°:-,-: L ------r-----l./*t I '•\'<,,<'-.<.ff./(, •. • •.• W~L SUBD~N •••• • •••• : •• ff( a, REAR SUBDRAIN: ACTIVE ZONE I BACKDRAIN TO70%OF WALL HEIGHT GRAVEL DRAINAGE FILL MIN 6" BELOW WALL MIN 12" BEHIND UNITS I FOUNDATION SOILS! 4" (MIN) DIAMETER PERFORATED PVC PIPE (SCHEDULE 40 OR EQUIVALENT) WITH PERFORATIONS DOWN. SURROUNDED BY NOTES: 1) MATERIAL GRADATION AND PLASTICITY REINFORCED ZONE· SIEVE SIZE 1 INCH NO.4 N0.40 NO. 200 % PASSING 100 20-100 0-60 0-35 FOR WALL HEIGHT< 10 FEET, PLASTICITY INDEX< 20 FOR WALL HEIGHT 10 TO 20 FEET, PLASTICITY INDEX< 10 FOR TIERED WALLS, USE COMBINED WALL HEIGHTS 1 CU. FT/FT OF 3/4" GRAVEL WRAPPED IN FILTER FABRIC (MIRAFI 140N OR EQUIVALENT) OUTLET SUBDRAINS EVERY 100 FEET, OR CLOSER, BY TIGHTLINE TO SUITABLE PROTECTED OUTLET GRAVEi DRAINAGE FILL" SIEVE SIZE % PASSING 1 INCH 100 3/4 INCH 75-100 NO.4 0-60 NO.40 0-50 NO. 200 0-5 WALL DESIGNER TO REQUEST SITE-SPECIFIC CRITERIA FOR WALL HEIGHT> 20 FEET 2) CONTRACTOR TO USE SOILS WITHIN THE RETAINED AND REINFORCED ZONES THAT MEET THE STRENGTH REQUIREMENTS OF WALL DESIGN . 3) GEOGRID REINFORCEMENT TO BE DESIGNED BY WALL DESIGNER CONSIDERING INTERNAL, EXTERNAL, AND COMPOUND STABILITY. 3) GEOGRID TO BE PRETENSIONED DURING INSTALLATION. 4) IMPROVEMENTS WITHIN THE ACTIVE ZONE ARE SUSCEPTIBLE TO POST-CONSTRUCTION SETTLEMENT. ANGLE 0'=45+<1>/2, WHERE <I> IS THE FRICTION ANGLE OF THE MATERIAL IN THE RETAINED ZONE. 5) BACKDRAIN SHOULD CONSIST OF J-DRAIN 302 (OR EQUIVALENT) OR 6-INCH THICK DRAINAGE FILL WRAPPED IN FILTER FABRIC. PERCENT COVERAGE OF BACKDRAIN TO BE PER GEOTECHNICAL REVIEW. SEGMENTAL RETAINING WALLS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAIL G Appendix E Geotechnical Engineering Report Important Information about Your Geotechnical Engineering Report Geoteclmical Services Are Performed for Specific Purposes, Persons, 1111 Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, preparPrl solelyfor the client. No one except you should rely on your geotechnica1 engineering report without first conferring with the geotechnical engineer who prepared it. And no one -not even you -should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotecbnical Engineering R8118rl II Based on A ~ique Set of Project-Speclflc Factors Geotechnical engineers consider a number of unique, project-specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical engineering report that was: • not prepared tor you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes-even minor ones-and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions C• Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineering report whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Andings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ-sometimes significantly- from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report's Recommendations Are Not Anal Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotachnical Engineering Report Is Subject to Misinterpretation Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Enlli•er's Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac- tors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled "limitations' many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvtronmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoenvi- ronmental information, ask your geotechnical consultant for risk manage- ment guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services per- fanned in connection with the geotschnical engineer's study were designed or conducted for the purpose of mold preven- tion. Proper Implementation of the recommendations conveyed in this report will not of itseff be sufficient to prevent mold from growing in or on the structure involl!Bd. Rely on Your ASFE-Member Geotecbnical Engineer for Additional Assistance Membership in ASFE/The Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk management techniques that can be of genuine benefit tor everyone involved with a construction project. Confer with your ASFE-member geotechnical engineer for more information. A -=~e THE GEOPROFESSIONAL .;;;ar-BUSINESS ASSOCIATION 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565 2733 Facsimile: 301/589-2017 e-mail: info@asfe org www.asfe.org Copyright 2004 by ASFE. Inc. Duplication, reproduction, or copying of /his document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE's specinc written pennission. Excerpting, quoting, or otherwise extracting wording from this cfocumer1t Is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotfl(;hnical engineering report. Any other firm, indiVidual, or other entity that so uses this document without being an ASFE member r:auld be committing negligent or intentional (fraudulenQ misrepresentation. IIGER01115,0MRP ATTACHMENT 9 Summary Files from the SWMM Model PRE-DEVELOPMENT EPA STORM WATER MANAGEMENT MODEL -VERSION 5.0 (Build 5.0.022) ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES Snowmelt ............... NO Groundwater ............ NO Flow Routing ........... NO Water Quality .......... NO Infiltration Method ...... GREEN AMPT Starti ng Date ............ OCT-17-1948 00:00:00 Ending Date .............. OCT-17-2005 23:00:00 Antecedent Dry Days ...... 0.0 Report Time Step ......... 01:00:00 Wet Time Step ............ 00:15:00 Dry Time Step ............ 04:00:00 ************************** Runoff Quantity Continuity ************************** Total Precipitation ..... . Evaporation Loss ........ . Infiltration Loss ....... . Surface Runoff .......... . Final Surface Storage ... . Continuity Error (%) ************************** Volume acre-feet 197.669 1. 864 181.427 15.685 0.000 -0.662 Depth inches 650 .290 6.132 596.859 51.602 0 .000 Volume Flow Routing Continuity Volume acre-feet 10'6 gal ************************** Dry Weather Inflow Wet Weather Inflow ...... . Groundwater Inflow ...... . RDII Inflow ............. . External Inflow ......... . External Outflow ........ . Internal Outflow ........ . Storage Losses .......... . Initial Stored Volume ... . Final Stored Volume ..... . Continuity Error (%) *************************** Subcatchment Runoff Summary *************************** Subcatchment Compacted Un compacted Total Precip in 650 .29 650.29 0.000 15 .685 0.000 0.000 0.000 15.685 0.000 0.000 0.000 0.000 0.000 Total Runon in 0.00 0.00 Analysis begun on: Wed Apr 08 15:20:10 2015 Analysis ended on: Wed Apr 08 15:20:30 2015 Total elapsed time: 00:00:20 0.000 5 .111 0.000 0.000 0.000 5 .111 0.000 0.000 0.000 0.000 Total Evap in 8.13 6.02 1 Total Infil in 585.78 597.47 Total Runoff in 61. 79 51. 04 Total Runoff 10'6 gal 0.32 4.79 Peak Runoff CFS 0.21 3.81 Runoff Coeff 0.095 0.078 POST-DEVELOPMENT EPA STORM WATER MANAGEMENT MODEL -VERSION 5.0 (Build 5.0.022) ********************************************************* NOTE : The summary statistics displayed i n this report are based on results found at every computational t i me step, n ot just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES Snowrnel t . . . . . . . . . . . . . . . NO Groundwater ............ NO Flow Routing ........... YES Ponding Allowed ........ NO Water Quality .......... NO Infiltration Method GREEN AMPT Flow Routing Method ...... KINWAVE Starting Date ............ OCT-17-1948 00:00:00 Ending Date .............. OCT-17-2005 23:00:00 Antecedent Dry Days ...... 0 .0 Report Time Step ......... 01:00:00 Wet Time Step ............ 00:15:00 Dry Time Step ............ 04:00:00 Routing Time Step ........ 60.00 sec WARNING 04: minimum elevation WARNING 04: minimum elevation WARNING 04: minimum elevation WARNING 04: minimum elevation ************************** Runoff Quantity Continuity ************************** Total Precipitation ..... . Evaporation Loss ........ . Infiltration Loss ....... . Surface Runoff .......... . Final Surface Storage ... . Continuity Error (%) ************************** Flow Routing Continuity ************************** Dry Weather Inflow Wet Weather Inflow Groundwater Inflow RDII Inflow ............. . External Inflow ......... . External Outflow ........ . Internal Outflow ........ . Storage Losses .......... . Initial Stored Volume ... . Final Stored Volume Continuity Error (%) drop used drop used drop used d rop used Volume acre-feet 197 .668 12.216 114. 868 72. 522 0.008 -0.984 Volume acre-feet 0.000 72. 518 0.000 0.000 0.000 72. 506 0.000 0.004 0.000 0.000 0.010 ******************************** Highest Flow Instability Indexes ******************************** for for for for Conduit BYPASS Conduit DUM 1 Conduit BYPASS Conduit DUM Depth inches 650 .290 40.188 377.894 238.582 0 .025 Volume lOA6 gal 1 0.000 23.631 0 .000 0.000 0.000 23.627 0.000 0.001 0.000 0 .000 2 1 2 - All links are stable. ************************* Routing Time Step Summary ************************* Minimum Time Step Average Time Step Maximum Time Step Percent in Steady State Average Iterations per Step *************************** Subcatchment Runoff Summary *************************** --------- Total Peak Runoff Runoff Coeff Subcatchment CFS AREA 1 3.27 0.375 LID 1 3.29 0.953 AREA 2 0 .88 0.375 LID 2 0.88 0.959 Precip in 650.29 650.29 650.29 650.29 *********************** LID Performance Summary *********************** ------------------- Final Pent. Storage Error Subcatchment LID Control in LID 1 BMP 1 1. 77 -0.50 LID 2 BMP 2 1. 76 -1. 03 ****************** Node Depth Summary ****************** Node Type POC OUTFALL DIV 1 DIVIDER DIV 2 DIVIDER BASIN 1 STORAGE -BASIN 2 STORAGE POST-DEVELOPMENT 60.00 sec 60 .00 sec 60 .00 sec 0.00 1.00 Total Runon in 0.00 16692.33 0.00 16691.23 Total Inflow in Total Evap in 27. 72 892.95 27.73 890.58 Evap Loss in Total Infil in 383.42 0.00 383.43 0 .00 Infil Loss in Total Runoff in 244.09 16534.16 244 .08 16627 .64 Surface Outflow in Total Runoff l0A6 gal 18.78 18.60 5 .05 5.03 Drain Outflow in 17342.62 17341.52 892.98 890.60 0.00 0.00 3638 .67 12896.06 1979.60 14648.55 Average Depth Feet 0.00 0.00 0.00 0.00 0.00 Maximum Maximum Time of Max Depth HGL Occurrence Feet Feet days hr:min 0.00 0.00 0 00:00 0.00 0.00 0 00:00 0.00 0 .00 0 00:00 0.85 0.85 19902 17:03 0.26 0.26 19902 17 :04 2 Init. Storage in 0.00 0.00 ******************* Node Inflow Summary ******************* Node Type POC OUTFALL DIV 1 DIVIDER DIV 2 DIVIDER BASIN 1 STORAGE BASIN 2 STORAGE ********************** Node Surcharge Summary ********************** POST-DEVELOPMENT Maximum Maximum Lateral Total Time of Max Inflow Inflow Occurrence CFS CFS days hr:min 0.00 4.18 19902 17:03 3.29 3.29 19902 17:00 0.88 0.88 19902 17:00 0.00 2.88 19902 17:00 0.00 0.84 19902 17:00 Lateral Inflow Volume 10A6 gal 0.000 18.603 5.027 0.000 0.000 Total Inflow Volume 10A6 gal 23.625 18.603 5 .027 1. 510 0.565 Surchargi ng occurs when water rises above the top of the highest conduit. Node DIV 1 DIV 2 BASIN 1 BASIN 2 ********************* Node Flooding Summary ********************* Type DIVIDER DIVIDER STORAGE STORAGE No nodes were flooded. ********************** St orage Volume Summary ********************** Storage Unit BASIN 1 BASIN 2 Average Volume 1000 ft3 0.000 0.000 *********************** Outfall Loading Summary *********************** Outfall Node POC System ******************** Link Flow Summary ******************** Flow Freq . Pent. 4.26 4.26 Hours Surcharged Max. Height Above Crown Feet 499679.02 499679.02 499679.02 499679.02 Avg E&I Pent Pent Full Loss Avg. Flow CFS 0.04 0.04 0 0 0 0 Max. Flow CFS 4 .18 4.18 3 0.000 0.000 0.850 0.264 Maximum Volume 1000 ft3 1.627 0.162 Total Volume 10A6 gal 23.625 23.625 Min. Depth Below Rim Feet 0.000 0.000 0.650 1. 236 Max Pent Full 56 16 Time of Max Occurrence days hr:min 19902 17:02 19902 17:03 Maximum Outflow CFS 2.89 0.84 Link Type BYPASS 1 DUMMY OUM 1 DUMMY BYPASS 2 DUMMY OUM 2 DUMMY OUTLET 1 DUMMY OUTLET 2 DUMMY ************************* Conduit Surcharge Summary ************************* POST-DEVELOPMENT Maximum IFlowl CFS 2 .88 0.41 0 .84 0.04 2.89 0.84 Time of Max Occurrence days hr:min 19902 17:00 1186 11: 49 19902 17:00 10671 14:56 19902 17:03 19902 17:04 Maximum IVelocl ft/sec Max/ Full Flow Max/ Full Depth Conduit ---------Hours Full-------- Both Ends Upstream Dnstream Hours Above Full Normal Flow Hours Capacity Limited BYPASS 1 OUM 1 BYPASS 2 OUM 2 0 .01 0 .01 0.01 0.01 0 .01 0.01 0.01 0.01 Analysis begun on: Wed Apr 08 16:33:36 2015 Analysis ended on: Wed Apr 08 16:34:19 2015 Total elapsed time: 00:00:43 4 0.01 499679.02 0.01 499679.02 0.01 499679 .02 0.01 499679.02 0 .01 0 .01 0.01 0.01 ATTACHMENT 10 Response to Comments 1 Job# 359-01 Response to Comments from SWMM Review for Afton Way 1. Page 1 comment: Explain why an area sizing factor of 0.035 was used. Does the required V1+V2 result from the area x the orifice I.E. to F.S. height? The basins were sized based on a volumetric calculation. The 0.035 sizing factor is not related to the volume calculations. 2. Page 2, 1st comment: Is there a flow thru planter LID model to account for impervious liner? The LID module in SWMM allows for the user to set it for no infiltration. 3. Page 2, 2nd comment: Puls? The Modified Puls routing is a common method used to route flows through a basin. 4. Page 5 comment on Figure la and lb: There is only one POC. Yes, there is only one POC. Please see updated report. 5. Attachment 1 comment on Q2 to QlO comparison: Q does not match (E) condition Q's in Table 7 of drainage report. Please clarify discrepancy. The Qs on Table 7 from the drainage study are based on a synthetic rainfall event, whereas the ones in Attachment 1 are based on the continuous hourly precipitation data from the Oceanside rain gage. 6. Attachment 2 comment on FDCs: Use dash or other means other than color to distinguish. Please see updated report. 7. Attachment 4 comment on Stage Storage: Gravel volume not correct. Please see updated report. 8. Attachment 4 comment on Stage Discharge Low Orifice: Low orifice 1.25" per table 1 pg.SO. The LID orifice is modeled in the LID module in SWMM. The 1.0 inch orifice on the stage-discharge table is not used, as the number of orifices is set to zero. Additionally, this Low Orifice refers to a surface orifice not LID orifice. 9. Attachment 4 comment on Stage Discharge: Explain what height this represents. Catch basin (emergency weir) is 1.75" from basin surface. "Lower" slot is 1.0' from surface. The elevations are measured 1.0 feet above the top of the amended soil layer, where the first surface discharge is located. Please see updated report. 2 Job# 359-01 10. Attachment 4 comment on Drawdown: Why doesn't Q discharge rate drop as head drops? The drawdown calculations have been updated. Please see revised report. 3 Job# 359-01 TORY R. WALKER ENGINEER1NG REL I ABLE SOLUT IO NS IN WATER RESOURCES Response to Comments Date of review: October 11, 2016 November 9, 2016 Job# 445-01 Re: REVIEW OF THE TECHNICAL MEMORANDUM: SWMM MODELING FOR HYDROMODIFICATION COMPLIANCE OF AFTON WAY. CITY OF CARLSBAD, CA. PREPARED FOR PRESIDIO MANA CARLSBAD 9, LLC, BY TRWE, APRIL 9, 2015. REVISED JUNE 17, 2015. 1. (Page 1) Apparent inconsistency between SWQMP and TRWE's HMP technical memorandum (TM) regarding nature of the soils: from our TM -"The site was modeled with Type B/C and Type O hydrologic soils ... ". Clarify why soils were modeled as B/C. TRWE Response: As noted in the HMP technical memorandum, our determination was based on our assessment of the more detailed "Geotechnical Investigation, Proposed Afton Way Residential Development, 2200 Afton Way Carlsbad, CA", by Leighton and Associates, Inc. (see Attachment 8). The apparent discrepancy is not a true discrepancy; rather, it is appropriate to utilize more site-specific and detailed soils data for the continuous simulation modeling, when available; it is likewise appropriate to, at the same time, use more general NRCS/County Hydrology Manual soils for typical hydrologic and/or water quality calculations. They do not need to be perfectly aligned. 2. (Pages 2 and 3) Surface depth of 2.5 feet (30 inches) in Basins 1 and 2 is inconsistent with plans and detail on OMA exhibit. TRWE Response: Plans and detail on DMA exhibit will be revised to be consistent with HMP technical memorandum. 3. (Attachment 4) Comment: Match detail on plans and OMA Exhibit. TRWE Response: Please refer to the note just above the table header that states "all elevations measure 1 foot above the amended soil." For calculation purposes, the spreadsheet emergency weir invert elevation must be 0.75 feet. Therefore, the 0.75-foot invert elevation corresponds to a 1.75-foot invert elevation on the plans and DMA exhibit. Both exhibits have been revised to reflect these specifications. WATERSHED, FLOODPLAIN f? STORM WATER MANAGEMENT • RIVER RESTORATION • FLOOD FACILITIES DESIGN • SEDIMENT 6--EROSION 122 CIVIC CENTER DRIVE, SUITE 2.06, VISTA CA 92084 · 760-414-9212 · TRWENCINEERING.COM -TRWE- Afton Way HMP Response to Comments November 9, 2016 4. (Attachment 6) Comment: Clarify how diversion structure is modified. TRWE Response: Please see details on revised plans. The diversion structure simply divides the flow in direct proportion to the square footage of the split-level BMP {21% to the smaller basin, 79% to the larger basin), thus ensuring proportional water quality treatment and hydromodification management. The total proposed project area has been divided proportionally into two separate subcatchments (21% and 79%, respectively) in order to model the diverted flow into each basin. 5. (Attachment 7) Comment: Reference City of Carlsbad BMP Design Manual. TRWE Response: Noted; due to the fact that this minor oversight would be the only reason to revise the report, and that it would not in any way change any conclusions or results, we request the missed reference be left as is. 6. Comment: Invert on plan details appears to be 1' -match. TRWE Response: The draft outlet structure rating curve spreadsheets in question had been inadvertently added to the report; please remove and refer to the spreadsheet titled "Outlet structure for Discharge of Biofiltration 1 and 2." 2 Job# 445-01