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AMEND 2018-0003; COASTLINE COMMUNITY CHURCH; STORM WATER QUALITY MANAGEMENT PLAN; 2023-01-01
STORM WATER QUALITY MANAGEMENT PLAN prepared for: Fuscoe Engineering, Inc. 6390 Greenwich Drive, Suite 170 San Diego, California 92122 858.554.1500 www.fuscoe.com Job # , CD2022-0024 FUSCOE ENGINEERING full circle th,nk ng® CITY OF CARLSBAD PRIORITY DEVELOPMENT PROJECT (PDP) PRELIMINARY STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) FOR COASTLINE COMMUNITY CHURCH PROJECT ID#AMEND2018-0003, SDP 02-16 DWG NO. 423-1C ENGINEER OF WORK: PREPARED FOR: COASTLINE COMMUNITY CHURCH 2215 CALLE BARCELONA CARLSBAD, CA 92009 (760) 753-0886 PREPARED BY: FUSCOE ENGINEERING, INC. 6390 GREENWICH DRIVE SAN DIEGO, CA 92122 858-554-1500 DATE: February 7, 2020 1 2 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 1a: DMA Exhibit/Hydromodification Management Exhibit · Existing Impervious Area Exhibit Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations (included on Attachment 1a) Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable) Attachment 1e: Pollutant Control BMP Design Worksheets / Calculations: · Worksheet B.5-1: BMP Sizing Worksheet · Worksheet B.5-3: County Alternate Minimum Biofiltration Footprint Ratio · San Diego County Rainfall 30 Year Annual Average Map · BMP Sizing Spreadsheet V2.0 for Hydromod Sizing · BMP-1 Volume Size Verification · BMP Drawdown Calculations Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit (included with Attachment 1a) 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 CERTIFICATION PAGE Project Name: Coastline Community Church Project ID: AMEND2018-0003 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. Eric Armstrong, PE Print Name Fuscoe En gineering, Inc. Company 02/07/2020 Date 3 4 PROJECT VICINITY MAP VICINITY MAP NOT TO SCALE CITY OF OCEANSIDE 78 CITY OF ENCINITAS ITY OF AN MARCOS PROJECT SITE 5 [Insert City’s Storm Water Standard Questionnaire (Form E-34) here] E-34 Page 1 of 4 REV 02/16 Development Services Land Development Engineering 1635 Faraday Avenue (760) 602-2750 www.carlsbadca.gov STORM WATER STANDARDS QUESTIONNAIRE E-34 INSTRUCTIONS: 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 INFORMATION PROJECT NAME: PROJECT ID: ADDRESS: APN: The project is (check one): New Development Redevelopment The total proposed disturbed area is: ________ ft2 (________) acres The total proposed newly created and/or replaced impervious area is: ________ ft2 (________) 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. C cityof Carlsbad □ □ E-34 Page 2 of 4 REV 02/16 STEP 1 TO BE COMPLETED FOR ALL PROJECTS To determine if your project is a “development project”, please answer the following question: YES NO 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)? 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): If you answered “no” to the above question, the project is a ‘development project’, go to Step 2. STEP 2 TO BE COMPLETED FOR ALL DEVELOPMENT PROJECTS 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: YES NO 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 guidance? 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? 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): If you answered “no” to the above questions, your project is not exempt from PDP, go to Step 3. □ □ □ □ □ □ □ □ E-34 Page 3 of 4 REV 02/16 STEP 3 TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS To determine if your project is a PDP, please answer the following questions (MS4 Permit Provision E.3.b.(1)): YES NO 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 public development projects on public or private 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 development projects on public or private 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 development project includes development on any natural slope that is twenty-five percent or greater. 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 transportation of automobiles, trucks, motorcycles, 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 project to the ESA (i.e. not commingled with flows from adjacent 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 (ADT) of 100 or more vehicles per day. 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) 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 stating “My project is a ‘STANDARD PROJECT’…” and complete applicant information. □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ STEP4 TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPMENT PROJECTS (PDP) ONLY Complete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)): YES NO 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) = 118•624 sq. ft. ~ □ Total proposed newly created or replaced impervious area (B) = 57,226 sq. ft. Percent impervious area created or replaced {B/A)*100 = 48·2 % 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 statina "Mv oroiect is a PDP ... " and complete aoolicant information. STEPS CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION ~ 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: Eric K. Arrfstrong f/ !l Applicant Title: Project Manager, Civil Engineer Applicant Signature: f 4-.~(~6 Date: 2 l !o {zoiv --) • Environmentally Sensitive Areas include but are not limited to all \Qe'an Water Act Section 303(d) Impaired water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (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 other equivalent environmentally sensitive areas which have been identified by the City. This Box for Citv Use Only YES NO City Concurrence: □ □ By: Date: Project ID: E-34 Page4 of4 REV 02/16 6 SITE INFORMATION CHECKLIST Project Summary Information Project Name Coastline Community Church Project ID SDP 02-16 Project Address 2215 Calle Barcelona Carlsbad, CA 92009 Assessor's Parcel Number(s) (APN(s)) 255-273-07-00 Project Watershed (Hydrologic Unit) Carlsbad 904 Parcel Area 6.430 Acres ( 280,090 Square Feet) Existing Impervious Area (subset of Parcel Area) 2.723 Acres (118,624 Square Feet) Area to be disturbed by the project (Project Area) 3.188 Acres ( 138,850 Square Feet) Project Proposed Impervious Area (subset of Project Area) 1.314 Acres ( 57,226 Square Feet) Project Proposed Pervious Area (subset of Project Area) 1.874 Acres ( 81,624 Square Feet) Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the Project. This may be less than the Parcel Area. 7 Description of Existing Site Condition and Drainage Patterns Current Status of the Site (select all that apply): x Existing development Previously graded but not built out Agricultural or other non-impervious use Vacant, undeveloped/natural Description / Additional Information: The project area currently consists of existing buildings, parking, and a playground. The site is currently zoned for religious purposes. Existing Land Cover Includes (select all that apply): x Vegetative Cover Non-Vegetated Pervious Areas x Impervious Areas Description / Additional Information: Existing pervious features of the site include landscape, vegetated areas, playground, and compacted native material. Impervious features of the site include buildings, sidewalks, roadway, and parking. Underlying Soil belongs to Hydrologic Soil Group (select all that apply): NRCS Type A NRCS Type B NRCS Type C x NRCS Type D The site consists mainly of Type D Soils, and a small portion of the northeast corner of the site consists of Type B Soils. Type D Soil will be used for design of the BMPs. Approximate Depth to Groundwater (GW): GW Depth < 5 feet 5 feet < GW Depth < 10 feet 10 feet < GW Depth < 20 feet x GW Depth > 20 feet Existing Natural Hydrologic Features (select all that apply): Watercourses Seeps Springs Wetlands x None Description / Additional Information: The site has been previously graded and developed, and there are no natural hydrologic features within the site. 8 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]: The existing (graded) topography slopes generally to the north and northeast. Runoff flows to the north via concrete brow ditches, swales, and a channel, and is collected in an existing desilting basin located at the northwest corner of the site. A portion of runoff flows via surface flow and gutter flow towards the northeast portion of the site, where it is collected by two catch basins. It flows slightly northwest via a 24” RCP storm drain pipe to a cleanout modified to serve as a low flow separator. Runoff then flows under Calle Barcelona via 24” and 36” RCP, and into the Arroya La Costa Tract development. Offsite runoff from the south flows into a brow ditch that flows east to west along the southern boundary of the site, and then flows north into the existing northwest detention basin, the flow is then collected and conveyed to the Arroya La Costa Tract development via the existing 24” RCP. 9 Description of Proposed Site Development and Drainage Patterns Project Description / Proposed Land Use and/or Activities: The project proposes to construct buildings for services and classrooms, and parking. The project will be completed in two phases, Phase 1 and Phase 2, and this study has been prepared to analyze the impacts of the ultimate buildout. Phase 1 of the proposed redevelopment consists of the construction of a new ministry building, playground, retaining walls, and parking stalls. Phase 2 of the proposed redevelopment consists of the expansion of the existing worship center, and the construction of a new maintenance building. Please refer to Attachment 1a for Phase 2 boundary. List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features): Proposed impervious features of the site include buildings, retaining wall, sidewalks, and parking. List/describe proposed pervious features of the project (e.g., landscape areas): Proposed pervious features of the site include permeable pavers, landscape, playground, and one of the proposed water quality basins. Does the project include grading and changes to site topography? x Yes No Description / Additional Information: The project will include grading for the parking lot and the new building, and proposed drainage will remain similar to the current drainage patterns. Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)? x Yes No Description / Additional Information: The project proposes to add storm drain, catch basins, biofiltration basins, and brow ditch modifications. 10 Identify whether any of the following features, activities, and/or pollutant source areas will be present (select all that apply): x On-site storm drain inlets Interior floor drains and elevator shaft sump pumps Interior parking garages x Need for future indoor & structural pest control x Landscape/Outdoor Pesticide Use Pools, spas, ponds, decorative fountains, and other water features Food service x Refuse areas Industrial processes Outdoor storage of equipment or materials Vehicle and Equipment Cleaning Vehicle/Equipment Repair and Maintenance Fuel Dispensing Areas Loading Docks x Fire Sprinkler Test Water Miscellaneous Drain or Wash Water x Plazas, sidewalks, and parking lots 11 Identification of Receiving Water Pollutants of Concern Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable): Runoff from the site flows to Batiquitos Lagoon, which then drains to 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)/Stressor(s) TMDLs Encinitas Creek Benthic Community Effects TMDL req’d Phosphorous, Selenium, Toxicity TMDL req’d for all Batiquitos Lagoon Toxicity TMDL req’d Identification of Project Site Pollutants Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see BMP Design Manual Appendix B.6): Pollutant Not Applicable to the Project Site Anticipated from the Project Site Also a Receiving Water Pollutant of Concern Sediment X Nutrients X X Heavy Metals X X Organic Compounds X Trash & Debris X Oxygen Demanding Substances X Oil & Grease X Bacteria & Viruses X Pesticides X 12 Hydromodification Management Requirements Do hydromodification management requirements apply (see Section 1.6 of the BMP Design Manual)? x Yes, hydromodification management flow control structural BMPs required. 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. 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. 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): Critical Coarse Sediment Yield Areas* *This Section only required if hydromodification management requirements apply Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas exist within the project drainage boundaries? Yes x 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? 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite 6.2.2 Downstream Systems Sensitivity to Coarse Sediment 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite 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? No critical coarse sediment yield areas to be protected based on verification of GLUs onsite Critical coarse sediment yield areas exist but additional analysis has determined that protection is not required. Documentation attached in Attachment 8 of the SWQMP. 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: NO CCSYAs exist within the project drainage boundary. 13 Flow Control for Post-Project Runoff* *This Section only required if hydromodification management requirements apply 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. There will be two POCs for hydromodification management. POC-1 will be located at the northwest corner of the site. POC-1 is the discharge point of the proposed biofiltration basin to the existing 24” storm drain running north of the site. POC-2 will be located at the existing inlet located on the west side of the Church’s entrance drive, and will serve as the discharge point for BMP-2 and BMP-3. Has a geomorphic assessment been performed for the receiving channel(s)? No, the low flow threshold is 0.1Q2 (default low flow threshold) Yes, the result is the low flow threshold is 0.1Q2 Yes, the result is the low flow threshold is 0.3Q2 X Yes, the result is the low flow threshold is 0.5Q2 If a geomorphic assessment has been performed, provide title, date, and preparer: Hydromodification Screening for La Costa Valley School Site Development, July 8, 2014, prepared by Chang Consultants Discussion / Additional Information: (optional) The geomorphic assessment was prepared for the La Costa Valley School, located adjacent to the project site (immediately east of the site). Both projects discharge to the channel, and the results of the assessment indicate the low flow threshold is 0.5Q2. 14 Other Site Requirements and Constraints 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 City codes governing minimum street width, sidewalk construction, allowable pavement types, and drainage requirements. The area available for BMP-2 and BMP-3 is very constrained and will not fit a biofiltration with graded side slopes, and therefore BMP-2 and BMP-3 will consist of a biofiltration basin with retaining walls instead of 3:1 slopes. Optional Additional Information or Continuation of Previous Sections As Needed This space provided for additional information or continuation of information from previous sections as needed. 15 [Insert City’s Standard Project Requirement Checklist Form E-36 (here)] E-36 Page 1 of 4 Revised 03/16 Development Services Land Development Engineering 1635 Faraday Avenue (760) 602-2750 www.carlsbadca.gov STANDARD PROJECT REQUIREMENT CHECKLIST E-36 Project Information Project Name: Project ID: DWG No. or Building Permit No.: Source Control BMPs 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 provided. Source Control Requirement Applied? SC-1 Prevention of Illicit Discharges into the MS4 Yes No N/A Discussion/justification if SC-1 not implemented: SC-2 Storm Drain Stenciling or Signage Yes No N/A Discussion/justification if SC-2 not implemented: SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Yes No N/A Discussion/justification if SC-3 not implemented: C cityof Carlsbad □ □ □ □ □ □ □ □ □ E-36 Page 2 of 4 Revised 03/16 Source Control Requirement (continued) Applied? SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Yes No N/A Discussion/justification if SC-4 not implemented: SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Yes No N/A Discussion/justification if SC-5 not implemented: SC-6 Additional BMPs based on Potential Sources of Runoff Pollutants must answer for each source listed below and identify additional BMPs. (See Table in Appendix E.1 of BMP Manual for guidance). On-site storm drain inlets Yes No N/A Interior floor drains and elevator shaft sump pumps Yes No N/A Interior parking garages Yes No N/A Need for future indoor & structural pest control Yes No N/A Landscape/Outdoor Pesticide Use Yes No N/A Pools, spas, ponds, decorative fountains, and other water features Yes No N/A Food service Yes No N/A Refuse areas Yes No N/A Industrial processes Yes No N/A Outdoor storage of equipment or materials Yes No N/A Vehicle and Equipment Cleaning Yes No N/A Vehicle/Equipment Repair and Maintenance Yes No N/A Fuel Dispensing Areas Yes No N/A Loading Docks Yes No N/A Fire Sprinkler Test Water Yes No N/A Miscellaneous Drain or Wash Water Yes No N/A Plazas, sidewalks, and parking lots Yes No N/A For “Yes” answers, identify the additional BMP per Appendix E.1. Provide justification for “No” answers. □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ E-36 Page 3 of 4 Revised 03/16 Site Design BMPs 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 provided. Source Control Requirement Applied? SD-1 Maintain Natural Drainage Pathways and Hydrologic Features Yes No N/A Discussion/justification if SD-1 not implemented: SD-2 Conserve Natural Areas, Soils, and Vegetation Yes No N/A Discussion/justification if SD-2 not implemented: SD-3 Minimize Impervious Area Yes No N/A Discussion/justification if SD-3 not implemented: SD-4 Minimize Soil Compaction Yes No N/A Discussion/justification if SD-4 not implemented: SD-5 Impervious Area Dispersion Yes No N/A Discussion/justification if SD-5 not implemented: I ID ID ID ID ID ID ID ID ID ID ID ID ID ID ID E-36 Page 4 of 4 Revised 03/16 Source Control Requirement (continued) Applied? SD-6 Runoff Collection Yes No N/A Discussion/justification if SD-6 not implemented: SD-7 Landscaping with Native or Drought Tolerant Species Yes No N/A Discussion/justification if SD-7 not implemented: SD-8 Harvesting and Using Precipitation Yes No N/A Discussion/justification if SD-8 not implemented: I ID ID ID ID ID ID ID ID ID 16 SUMMARY OF PDP STRUCTURAL BMPS 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 City 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 City 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 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 together or separate. The Coastline Community Church project proposes to limit the amount of impervious area that will be newly created or replaced, in order to reduce the footprint of the structural BMP. Biofiltration basins will be utilized to provide both pollutant control and flow control. Harvest and reuse of storm water is considered infeasible due to lack of indoor demand, and the infeasibility of modifying the existing irrigation system to integrate storm water reuse. Infiltration is partially feasible due to the low infiltration characteristics of Hydrologic Group D soils. Therefore the most effective and feasible BMP for this site is a biofiltration basin (BF-1), which will be shown as BMP-1, BMP-2, and BMP-3 on the plans. BMP-1 will be located at the northwest corner of the site, and will have lined sides and an open bottom to allow for partial infiltration. BMP-2 and BMP-3 are located near the center of the site, and the bottom and sides will be lined to prevent infiltration due to proximity to retaining walls.The BMPs have been sized using the BMP Sizing Spreadsheet V2.0, and shall be used to meet both pollutant control and hydromodification requirements. Additionally, the site creates and/or replaces less than 50% of the existing impervious area, therefore the BMP has been sized to treat only new and replaced impervious area. See Page 6 of this report for quantified area. 17 [Continued from previous page – This page is reserved for continuation of description of general strategy for structural BMP implementation at the site.] BMP-1 Strategy: BMP-1 has been sized to: 1) Meet hydromodification and pollutant control requirements for runoff generated by the new project, and 2) Store and treat 75% of the design capture volume (DCV) collected from existing areas which are: o a portion of existing roof runoff (DMA-1E), and o the area tributary to an existing 6” low-flow pipe (DMA-1D). Via the existing 6” low-flow pipe, BMP-1 receives runoff from approximately 3.67 acres of the existing project and all areas tributary to BMP-2 and BMP-3. The area tributary to the low-flow pipe is quantified as DMA-1D on the DMA Exhibit, and the existing roof runoff tributary to BMP-1 is quantified as DMA-1E. To reiterate, BMP-1 has been designed to store: 1) the hydromod volume generated by portions of the new project (DMA-1A, 1B, and 1C), as well as 2) 75% of the DCV of the existing runoff (DMA-1D and 1E) tributary to the basin, per Option 2 of Section B.5 of Carlsbad BMP Manual: Storage Calculations: 1) Per the Country BMP Sizing Spreadsheet in Attachment 1e, the required hydromod volume generated by the project for BMP-1 is: · 3024 cubic feet (1759 CF +1265 CF). 2) The pollutant control DCV generated from the existing roof runoff (DMA-1E) & 6” low-flow pipe (DMA-1D) is calculated using the DCV equation in Section B.1 of Carlsbad BMP Manual: DCV= 3630 x C x d x A For this project, C= 0.56 (Runoff factor per Section B.1.1, calculated below and shown in Attachment 1a/1b) d= 0.58 (85th Percentile, 24-hr storm depth in inches) A= 3.73 acres (DMA-1E and DMA 1-D) Existing Area Tributary to BMP-1 DMA- 1E DMA-1D Subtotal sf C Factor Weighted Area Weighted C Impervious (sf) 2,350 91,250 93,600 0.9 84240 0.56 Pervious (sf) 0 68,730 68,730 0.1 6873 Subtotal (sf) 2,350 159,980 Subtotal (acres) 0.054 3.673 Total Acres 3.73 The pollutant control DCV = 3630 x 0.56 x 0.58 x 3.73 =4398 CF , and 75% of the DCV is · 3299 cubic feet (0.75 x 4398 = 3299) Storage Required and Provided: As calculated above, the required hydromod volume plus 75% of the DCV is: 3,024 CF + 3,299 CF = 6,323 CF Thefore, the total required storage volume of BMP-1 is 6,323 CF. The total volume provided in BMP-1 is 7,013 cubic feet. Required and provided volume calculations are tabulated in Appendix 1e. Please see Attachment 1a/1b-DMA Exhibit, for area breakdowns and tabulated values. B.5 Biofiltration BMPs Biofiltration BMPs shall be sized by one of the following sizing methods: Option 1: Treat 1.5 times the portion of the DCV not reliably retained onsite, O R Option 2: Treat 1.0 times the portion of the DCV not reliably reL'lined onsite; and additionally check that the system has a total static (i.e., non-routed) storage volume, including pore spaces and pre-filter detention volume, equal to at least 0.75 times the portion of the DCV not reliably retained onsite. 18 [Continued from previous page – This page is reserved for continuation of description of general strategy for structural BMP implementation at the site.] BMP-3 Strategy: The impervious area of the garden chapel and stairs between the parking lot has been included in the stormwater analysis. The location of the garden chapel (DMA-6B) and stairs between the parking lots (DMA-6A) make hydromodification and treatment difficult, and therefore an equivalent amount of existing impervious area (DMA-3D, portion of existing parking lot) will be diverted to BMP-3 for treatment. Please see the DMA Exhibit in Attachment 1 for further information. 19 Structural BMP Summary Information [Copy this page as needed to provide information for each individual proposed structural BMP] Structural BMP ID No. BMP-1 DWG AMEND2018-0003 Sheet No. 3 Type of structural BMP: Retention by harvest and use (HU-1) Retention by infiltration basin (INF-1) Retention by bioretention (INF-2) Retention by permeable pavement (INF-3) X Partial retention by biofiltration with partial retention (PR-1) Biofiltration (BF-1) 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) Detention pond or vault for hydromodification management Other (describe in discussion section below) Purpose: Pollutant control only Hydromodification control only x Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP Other (describe in discussion section below) Discussion (as needed): 20 Structural BMP Summary Information [Copy this page as needed to provide information for each individual proposed structural BMP] Structural BMP ID No. BMP-2 DWG AMEND2018-0003 Sheet No. 4 Type of structural BMP: Retention by harvest and use (HU-1) Retention by infiltration basin (INF-1) Retention by bioretention (INF-2) Retention by permeable pavement (INF-3) Partial retention by biofiltration with partial retention (PR-1) X Biofiltration (BF-1) 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) Detention pond or vault for hydromodification management Other (describe in discussion section below) Purpose: Pollutant control only Hydromodification control only x Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP Other (describe in discussion section below) Discussion (as needed): 21 Structural BMP Summary Information [Copy this page as needed to provide information for each individual proposed structural BMP] Structural BMP ID No. BMP-3 DWG _______ Sheet No. _______ Type of structural BMP: Retention by harvest and use (HU-1) Retention by infiltration basin (INF-1) Retention by bioretention (INF-2) Retention by permeable pavement (INF-3) Partial retention by biofiltration with partial retention (PR-1) X Biofiltration (BF-1) 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) Detention pond or vault for hydromodification management Other (describe in discussion section below) Purpose: Pollutant control only Hydromodification control only x Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP Other (describe in discussion section below) Discussion (as needed): 22 ATTACHMENT 1 BACKUP FOR PDP POLLUTANT CONTROL BMPS This is the cover sheet for Attachment 1. Check which Items are Included behind this cover sheet: Attachment Sequence Contents Checklist Attachment 1a DMA Exhibit (Required) See DMA Exhibit Checklist on the back of this Attachment cover sheet. (24”x36” Exhibit typically required) ☒ Included Also Included: · Existing Impervious Area Exhibit Attachment 1b Tabular Summary of DMAs Showing DMA ID matching DMA Exhibit, DMA Area, and DMA Type (Required)* *Provide table in this Attachment OR on DMA Exhibit in Attachment 1a ☒ Included on DMA Exhibit in Attachment 1a Included as Attachment 1b, separate from DMA Exhibit Attachment 1c Form I-7, Harvest and Use Feasibility Screening Checklist (Required unless the entire project will use infiltration BMPs) Refer to Appendix B.3-1 of the BMP Design Manual to complete Form I-7. ☒ Included Not included because the entire project will use infiltration BMPs Attachment 1d Form I-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 I-8. ☒ Included Not included because the entire project will use harvest and use BMPs Attachment 1e Pollutant Control BMP Design Worksheets / Calculations (Required) Refer to Appendices B and E of the BMP Design Manual for structural pollutant control BMP design guidelines ☒ Included: · Worksheet B.5-1: BMP Sizing Worksheet · Worksheet B.5-3: County Alternate Minimum Biofiltration Footprint Ratio · San Diego County Rainfall 30 Year Annual Average Map · BMP Sizing Spreadsheet V2.0 for Hydromod Sizing · BMP-1 Volume Size Verification · BMP Drawdown Calculations 23 Use this checklist to ensure the required information has been included on the DMA Exhibit: The DMA Exhibit must identify: ☒ Underlying hydrologic soil group ☒ Approximate depth to groundwater ☒ Existing natural hydrologic features (watercourses, seeps, springs, wetlands) ☒ Critical coarse sediment yield areas to be protected (if present) ☒ Existing topography and impervious areas ☒ Existing and proposed site drainage network and connections to drainage offsite ☒ Proposed grading ☒ Proposed impervious features ☒ Proposed design features and surface treatments used to minimize imperviousness ☒ Drainage management area (DMA) boundaries, DMA ID numbers, and DMA areas (square footage or acreage), and DMA type (i.e., drains to BMP, self-retaining, or self- mitigating) ☒ Structural BMPs (identify location and type of BMP) COASTLINE COMMUNITY CHURCH DMA AND HYDROMODIFICATION MANAGEMENT EXHIBIT 02/06/2020 SITE DATA UNDERLYING HYDROLOGIC SOIL GROUP: D DEPTH TO GROUNDWATER: >15 FEET EXISTING HYDROLOGIC FEATURES ONSITE: NONE CRITICAL COARSE SEDIMENT YIELD AREAS: NONE BMP-3: BIOFILTRATION BASIN BMP-2: BIOFILTRATION BASIN NOTES: TO COMPLY WITH COUNTY OF SD 2019 BMP WORKSHEET B.4 (REDUCED SIZE BMP MAINTENANCE INTERVAL WORKSHEET): A. BMP-1, BMP-2, AND BMP-3 SHALL HAVE VEGETATIVE COVER OF AT LEAST 75%. (TO SATISFY LOAD TO CLOG =3.0) B. MAJOR BMP MAINTENANCE SHALL BE ONCE EVERY 10 YEARS SEE APPENDIX 1e IN PROJECT SWQMP Attachment 1a/1b: BMP-1: BIOFILTRATION BASIN (FOR POLLUTANT CONTROL AND HYDROMODIFICATION) GNIREENE IGN 6390 Greenwich Dr., Suite 170, San Diego, California 92122 tel 858.554.1500 fax 858.597.0335 www.fuscoe.com LEGEND 18-INCH THICK LA YER OF B/OF/L TRA TION SOIL MIX (BSM) PER CITY OF CARLSBAD BMP DESIGN MANUAL 24 INCH THICK LA YER OPEN GRADED SUB-BASE COURSE, (157 STONE, 40% VOIDS WIDTH VARIES PER PLAN SF @ TOP OF PONDING PER PLAN HEADWALL PER PLAN c., . ;;; .... C) I~ I ~:=---SIDES OF BASIN TO BE J" NOT TO SCAL[ 2.25" ORIFICE PLATE 76.86 IE LINED WITH IMPERMEABLE LINER, 30 MIL THICK HOPE I 1- 7: 1 SLOPE (FOR -MEDIA LAYERS) ----~ 6-/NCH THICK LA YER OF "BIRDSEYE" WASHED PEA GRAVEL -CHOKER STONE LAYER DISCHARGE TO POC-1 (EXISTING 24" STORM DRAIN @ CALLE BARCELONA) ~ 50' o· 25' 50' SCALE: 1 " = 50' PROJECT BOUNDARY PROPOSED CONTOUR MAJOR PROPOSED CONTOUR MINOR EXISTING STORM DRAIN EXISTING IMPERVIOUS AREA TRIBUTARY TO BMP-2 PROPOSED IMPERVIOUS AREA PERMEABLE PAVERS PERVIOUS AREA PROPOSED RETAINING WALL BIOFILTRATION BASIN DMA BOUNDARY AREA TRIBUTARY TO LOW-FLOW PIPE EXISTING AREA TRIBUTARY TO BMP-1 PHASE 2 BOUNDARY EXISTING BROW DITCH PROPOSED BROW DITCH PROPOSED STORM DRAIN ------13u------- ------12'1------- ------- --------■■-■■-■■- =>·=>·=>·=>·=>·=> WIDTH VARIES PER PLAN 123.0 TW SF @ BgT BASIN PER PLAN 131.6 :a: "' :i ti • e:i "' l,J 123.0 TW c:: 122.5 TG R[lAINING-= 1 ~~==:~~=t-r WALL __ - - / //- 6-tlNCH THICK LA YER i BIRDSEYE" WASHED PE / GRAVEL -CHOKER m.3 STONE LA YER 12 INCH THICK LA YE OPEN GRADED SUB-BAS COURSE, #57 STONE, 40 m.4 VOIDS I BOTTOM AND SIDES OF BASIN TO BE LINED WITH IMPERMEABLE LINER, 30 MIL THICK HOPE NOT TO SCALE 132.7 DMA and BMP Table T DMA Total Area to BMP sf acres sf acres DMA-1A 55,179 1.27 DMA-1B 10,575 0.24 DMA-1C 9,642 0.22 DMA-1D (tributary to existing 6" low-159,980 3.67 237,726 546 flow) 1 DMA-1E (existing roof tributary to 2,350 0054 BMP-1/ DMA-2 4,570 0.10 DMA-3A 14,693 0.34 DMA-3B 3,760 0.09 DMA-3C 1,247 0.03 20,490 0.47 DMA-3D (existing . . 2 790 002 1mperv1ous) DMA-4 34,400 0.79 DMA-5 3,900 009 DMA-6A2 250 0.01 DMA-6B2 505 0.01 DMA-7A 99 0.00 DMA-7B 166 ODO Total 301,316 6.92 3• 18-INCH THICK LAYER OF B/OF/L TRA TION SOIL MIX (BSM) PER CITY OF CARLSBAD BMP DESIGN MANUAL J EX/STING 6" CURB EXISTING PARKING LOT --------- IE PER PLAN SIDEWALK UNDER DRAIN PIPE PER D-27 0. 5" ORIFICE PLATE 118.75 IE Pervious Area Pervious Area New or existing 3 (Permeable (Landscape) Weighted Impervious Area (C factor Pavers or Area (C factor= 0.9) =0.1) Turf) (C factor =0.31 sf sf sf 37,689 17,490 0 35,669 0 10,575 3,173 0 0 9,642 2,893 91,250 68,730 88,998 2.350 0 2,115 3,976 594 3,638 10,955 3,738 10,233 3,342 418 3,050 1,247 0 1,122 790 0 71 1 0 34,400 3,440 0 3,479 348 250 0 225 505 0 455 99 0 89 166 0 149 58,229 128,849 20,217 156,307 RETAIN/NG_..:;Uf~ftl::;:;:tf WALL 6-INCH THICK LA YER 0 "BIRDSEYE" WASHED PE GRAVEL -CHOKER STONE LAYER 12 INCH THICK LA YE OPEN GRADED SUB-BAS COURSE, #57 STONE, 40 VOIDS WIDTH VARIES PER PLAN SF @ BOT BASIN PER PLAN 113.3 TG BOTTOM AND sI0Es oF~?+t,=t"'.:::5 W BASIN TO BE LINED WI TH IMPERMEABLE LINER, 30 MIL THICK HOPE Weighted C (Water 4 Treatment Quality) Method unitless unitless uniUess 0.55 BMP-1 0.56 056 (Biofiltration, BF- 1) 0.56 090 BMP-2 0.80 (Biofiltration, BF- 1) BMP-3 0.74 (Biofiltration, BF- 1) 0.10 Se~-Mitigating 009 Se~-Mitigating 0.90 An equivalent amount of existing runoff 0.90 (DMA-3D) is direc ted to BMP- ' 0.90 De Minimis 090 De Minimis 1.2" ORIFICE PLATE 109.55 IE NOT TO SCALE Size Reau1red Pollutant Hydromodi Control ficati on sf cf 3042 2825 - 105 289 455 1201 - - -- -- - Pollutant Control ocv5 cf - 4,398 - - . - - J EX/STING 6" CURB I 1f I~ ~:;['IT ...fX/STING_f'ARKIN/i. LOT =111=111= --18-INCH THICK LA YER OF :B/OFIL TRA TION SOIL MIX =(BSM) PER CITY OF -111:CARLSBAD BMP DESIGN -·f.1.A,NUAL 11 I' I I I I I II I ill 11 OUTLET PIPE, IE PER PLAN Size Provided Pollutant Hydro mod Control ification sf cf 2825 7013 1 240 456 915 1710 -- -- - - - - -- 12" HOPE ULTIMATELY DISCHARGES TO POC-2 (EXISTING 36" STORM DRAIN @ CALLE BARCELONA) 7 O rifice Drawdown Diameter Time ,n hr 225 79 0.50 13.7 1.20 9.0 - - -- -- - 1 . . . . . . BMP-1 has been s ized to capture the hydromod volume generated by DMA-1A, 18 , and 1C (3042 CF) as well as store 0.75 x DCVentenng BMP-1 v,a DMA-1E (ex1st1ng roof runoff) and DMA-1D (runoff from the 6" low -flow pipe). (4398'0.75= 3299 CF). See Page 16-17 "Summary of PDP Structural BMPs" in Project SWQMP for supporti ng calculations 2 . . . . . . . . . . Note: Dlv1A-6A and DIVlA-6B (garden chapel and parking lot stairs) are difficult to treat ons1te due to their location. Therefore, the City of Carlsbad has allowed for an equal volume of runoff from an area not im pacted by the project, to be treated by a proposed BMP. To com ply with this allowance, DMA-3D (portion existing parking lot) has been routed to BMP-3. 3 Existing and numbers in red indicate that the area 1s existing area. Existing 1mpeivious area is not included in the total impervious area quantity. 4 5 Weighted Runoff calculated per Appendix B, Section B.1 of Carlsbad BMP 1\/lanual: B.1.1 Runoff Fac tor Estimate the area weighted runoff factor for the tributary area to the BMP using runoff factor (from Tabk 8 .1-1) anJ ~1rt:a uf ed.th surfac..:c Lypcc in t.hc ccibutary arc11 a11J Lhe folluwin.g t.x-1uation: C = Runoff factor for area X t\,. = Tributa ry area X (acres) L C,A, C = --=--,--L Ax DCV calculated per /lj)pendix B, Section B.1 of Carlsbad BMP Manual: l l NOTES: 1. THE TOTAL CREATED AND/OR REPLACED IMPERVIOUS AREA IS LESS THAN 50% OF THE EXISTING IMPERVIOUS AREA. (1.314 ACRES/ 2.723 ACRES =48.3%). THEREFORE, THE PROJECT QUALIFIES FOR THE 50% RULE PER SECTION 1.7 OF THE BMP MANUAL (CARLSBAD BMP DESIGN MANUAL, 2016) AND IS THEREFORE TREATING ONLY THE IMPERVIOUS AREA CREATED/REPLACED. SEE PROJECT SWQMP FOR SUPPORT CALCULATIONS. EXISTING IMPERVIOUS AREA = CREATED/REPLACED IMPERVIOUS AREA - 1.316/2.723= 48.2% 2.723 ACRES 1.314 ACRES 0 0 0 m 0 0 w 0 0 "-" m u 0 0 ., " 0 " I 0 N I 0 t 0 0 0 0 ~ I / 0 0 / c- c;/ ;) 2 u m -~ "-/ ~----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------~'- COASTLINE COMMUNITY CHURCH DMA AND HYDROMODIFICATION MANAGEMENT EXHIBIT 02/06/2020 SITE DATA UNDERLYING HYDROLOGIC SOIL GROUP: D DEPTH TO GROUNDWATER: >15 FEET EXISTING HYDROLOGIC FEATURES ONSITE: NONE CRITICAL COARSE SEDIMENT YIELD AREAS: NONE BMP-3: BIOFILTRATION BASIN BMP-2: BIOFILTRATION BASIN NOTES: TO COMPLY WITH COUNTY OF SD 2019 BMP WORKSHEET B.4 (REDUCED SIZE BMP MAINTENANCE INTERVAL WORKSHEET): A. BMP-1, BMP-2, AND BMP-3 SHALL HAVE VEGETATIVE COVER OF AT LEAST 75%. (TO SATISFY LOAD TO CLOG =3.0) B. MAJOR BMP MAINTENANCE SHALL BE ONCE EVERY 10 YEARS SEE APPENDIX 1e IN PROJECT SWQMP Attachment 1a/1b: BMP-1: BIOFILTRATION BASIN (FOR POLLUTANT CONTROL AND HYDROMODIFICATION) GNIREENE IGN 6390 Greenwich Dr., Suite 170, San Diego, California 92122 tel 858.554.1500 fax 858.597.0335 www.fuscoe.com LEGEND 18-INCH THICK LA YER OF B/OF/L TRA TION SOIL MIX (BSM) PER CITY OF CARLSBAD BMP DESIGN MANUAL 24 INCH THICK LA YER OPEN GRADED SUB-BASE COURSE, (157 STONE, 40% VOIDS WIDTH VARIES PER PLAN SF @ TOP OF PONDING PER PLAN HEADWALL PER PLAN c., . ;;; .... C) I~ I ~:=---SIDES OF BASIN TO BE J" NOT TO SCAL[ 2.25" ORIFICE PLATE 76.86 IE LINED WITH IMPERMEABLE LINER, 30 MIL THICK HOPE I 1- 7: 1 SLOPE (FOR -MEDIA LAYERS) ----~ 6-/NCH THICK LA YER OF "BIRDSEYE" WASHED PEA GRAVEL -CHOKER STONE LAYER DISCHARGE TO POC-1 (EXISTING 24" STORM DRAIN @ CALLE BARCELONA) ~ 50' o· 25' 50' SCALE: 1 " = 50' PROJECT BOUNDARY PROPOSED CONTOUR MAJOR PROPOSED CONTOUR MINOR EXISTING STORM DRAIN EXISTING IMPERVIOUS AREA TRIBUTARY TO BMP-2 PROPOSED IMPERVIOUS AREA PERMEABLE PAVERS PERVIOUS AREA PROPOSED RETAINING WALL BIOFILTRATION BASIN DMA BOUNDARY AREA TRIBUTARY TO LOW-FLOW PIPE EXISTING AREA TRIBUTARY TO BMP-1 PHASE 2 BOUNDARY EXISTING BROW DITCH PROPOSED BROW DITCH PROPOSED STORM DRAIN ------13u------- ------12'1------- ------- --------■■-■■-■■- =>·=>·=>·=>·=>·=> WIDTH VARIES PER PLAN 123.0 TW SF @ BgT BASIN PER PLAN 131.6 :a: "' :i ti • e:i "' l,J 123.0 TW c:: 122.5 TG R[lAINING-= 1 ~~==:~~=t-r WALL __ - - / //- 6-tlNCH THICK LA YER i BIRDSEYE" WASHED PE / GRAVEL -CHOKER m.3 STONE LA YER 12 INCH THICK LA YE OPEN GRADED SUB-BAS COURSE, #57 STONE, 40 m.4 VOIDS I BOTTOM AND SIDES OF BASIN TO BE LINED WITH IMPERMEABLE LINER, 30 MIL THICK HOPE NOT TO SCALE 132.7 DMA and BMP Table T DMA Total Area to BMP sf acres sf acres DMA-1A 55,179 1.27 DMA-1B 10,575 0.24 DMA-1C 9,642 0.22 DMA-1D (tributary to existing 6" low-159,980 3.67 237,726 546 flow) 1 DMA-1E (existing roof tributary to 2,350 0054 BMP-1/ DMA-2 4,570 0.10 DMA-3A 14,693 0.34 DMA-3B 3,760 0.09 DMA-3C 1,247 0.03 20,490 0.47 DMA-3D (existing . . 2 790 002 1mperv1ous) DMA-4 34,400 0.79 DMA-5 3,900 009 DMA-6A2 250 0.01 DMA-6B2 505 0.01 DMA-7A 99 0.00 DMA-7B 166 ODO Total 301,316 6.92 3• 18-INCH THICK LAYER OF B/OF/L TRA TION SOIL MIX (BSM) PER CITY OF CARLSBAD BMP DESIGN MANUAL J EX/STING 6" CURB EXISTING PARKING LOT --------- IE PER PLAN SIDEWALK UNDER DRAIN PIPE PER D-27 0. 5" ORIFICE PLATE 118.75 IE Pervious Area Pervious Area New or existing 3 (Permeable (Landscape) Weighted Impervious Area (C factor Pavers or Area (C factor= 0.9) =0.1) Turf) (C factor =0.31 sf sf sf 37,689 17,490 0 35,669 0 10,575 3,173 0 0 9,642 2,893 91,250 68,730 88,998 2.350 0 2,115 3,976 594 3,638 10,955 3,738 10,233 3,342 418 3,050 1,247 0 1,122 790 0 71 1 0 34,400 3,440 0 3,479 348 250 0 225 505 0 455 99 0 89 166 0 149 58,229 128,849 20,217 156,307 RETAIN/NG_..:;Uf~ftl::;:;:tf WALL 6-INCH THICK LA YER 0 "BIRDSEYE" WASHED PE GRAVEL -CHOKER STONE LAYER 12 INCH THICK LA YE OPEN GRADED SUB-BAS COURSE, #57 STONE, 40 VOIDS WIDTH VARIES PER PLAN SF @ BOT BASIN PER PLAN 113.3 TG BOTTOM AND sI0Es oF~?+t,=t"'.:::5 W BASIN TO BE LINED WI TH IMPERMEABLE LINER, 30 MIL THICK HOPE Weighted C (Water 4 Treatment Quality) Method unitless unitless uniUess 0.55 BMP-1 0.56 056 (Biofiltration, BF- 1) 0.56 090 BMP-2 0.80 (Biofiltration, BF- 1) BMP-3 0.74 (Biofiltration, BF- 1) 0.10 Se~-Mitigating 009 Se~-Mitigating 0.90 An equivalent amount of existing runoff 0.90 (DMA-3D) is direc ted to BMP- ' 0.90 De Minimis 090 De Minimis 1.2" ORIFICE PLATE 109.55 IE NOT TO SCALE Size Reau1red Pollutant Hydromodi Control ficati on sf cf 3042 2825 - 105 289 455 1201 - - -- -- - Pollutant Control ocv5 cf - 4,398 - - . - - J EX/STING 6" CURB I 1f I~ ~:;['IT ...fX/STING_f'ARKIN/i. LOT =111=111= --18-INCH THICK LA YER OF :B/OFIL TRA TION SOIL MIX =(BSM) PER CITY OF -111:CARLSBAD BMP DESIGN -·f.1.A,NUAL 11 I' I I I I I II I ill 11 OUTLET PIPE, IE PER PLAN Size Provided Pollutant Hydro mod Control ification sf cf 2825 7013 1 240 456 915 1710 -- -- - - - - -- 12" HOPE ULTIMATELY DISCHARGES TO POC-2 (EXISTING 36" STORM DRAIN @ CALLE BARCELONA) 7 O rifice Drawdown Diameter Time ,n hr 225 79 0.50 13.7 1.20 9.0 - - -- -- - 1 . . . . . . BMP-1 has been s ized to capture the hydromod volume generated by DMA-1A, 18 , and 1C (3042 CF) as well as store 0.75 x DCVentenng BMP-1 v,a DMA-1E (ex1st1ng roof runoff) and DMA-1D (runoff from the 6" low -flow pipe). (4398'0.75= 3299 CF). See Page 16-17 "Summary of PDP Structural BMPs" in Project SWQMP for supporti ng calculations 2 . . . . . . . . . . Note: Dlv1A-6A and DIVlA-6B (garden chapel and parking lot stairs) are difficult to treat ons1te due to their location. Therefore, the City of Carlsbad has allowed for an equal volume of runoff from an area not im pacted by the project, to be treated by a proposed BMP. To com ply with this allowance, DMA-3D (portion existing parking lot) has been routed to BMP-3. 3 Existing and numbers in red indicate that the area 1s existing area. Existing 1mpeivious area is not included in the total impervious area quantity. 4 5 Weighted Runoff calculated per Appendix B, Section B.1 of Carlsbad BMP 1\/lanual: B.1.1 Runoff Fac tor Estimate the area weighted runoff factor for the tributary area to the BMP using runoff factor (from Tabk 8 .1-1) anJ ~1rt:a uf ed.th surfac..:c Lypcc in t.hc ccibutary arc11 a11J Lhe folluwin.g t.x-1uation: C = Runoff factor for area X t\,. = Tributa ry area X (acres) L C,A, C = --=--,--L Ax DCV calculated per /lj)pendix B, Section B.1 of Carlsbad BMP Manual: l l NOTES: 1. THE TOTAL CREATED AND/OR REPLACED IMPERVIOUS AREA IS LESS THAN 50% OF THE EXISTING IMPERVIOUS AREA. (1.314 ACRES/ 2.723 ACRES =48.3%). THEREFORE, THE PROJECT QUALIFIES FOR THE 50% RULE PER SECTION 1.7 OF THE BMP MANUAL (CARLSBAD BMP DESIGN MANUAL, 2016) AND IS THEREFORE TREATING ONLY THE IMPERVIOUS AREA CREATED/REPLACED. SEE PROJECT SWQMP FOR SUPPORT CALCULATIONS. EXISTING IMPERVIOUS AREA = CREATED/REPLACED IMPERVIOUS AREA - 1.316/2.723= 48.2% 2.723 ACRES 1.314 ACRES 0 0 0 m 0 0 w 0 0 "-" m u 0 0 ., " 0 " I 0 N I 0 t 0 0 0 0 ~ I / 0 0 / c- c;/ ;) 2 u m -~ "-/ ~----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------~'- LEGEND COASTLINE COMMUNITY CHURCH EXISTING IMPERVIOUS AREA EXHIBIT 10/3/2019 GNIREENE IGN 6390 Greenwich Dr., Suite 170, San Diego, California 92122 tel 858.554.1500 fax 858.597.0335 www.fuscoe.com EXISTING IMPERVIOUS AREA TABLE 131.0 ~< ?' . ,/' = ,,-, PROJECT BOUNDARY ~;~~:G IMPERVIOUS DITCH) AREA EXISTING IM (VARIOUS H:;i:1ous AREA PATTERNS) Descript' 10n Walkwav Walkway Building, Parking Walkway ' Building W lk . , a way Driveway p k. , ar 1ng Driveway Pa k. , r 1ng Walkwav Browditch C urb To tal SF Total Acres -- - lmpe • rv1ous Area (sf) 5,00 2 3,78 9 31,040 14,705 5,985 53,082 l ,95 7 2,894 170 l l 8,624 2.72 SCALE: 1 " 0 0 25' 50' 50' 0 rn 0 C © © 0 Appendix H: Guidance for Investigation Potential Critical Coarse Sediment Yield Areas Storm Water Standards Part 1: BMP Design Manual January 2016 Edition I-3 Harvest and Use Feasibility Checklist Form I-7 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 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. [Provide a summary of calculations here] 3. Calculate the DCV using worksheet B-2.1. DCV = __________ (cubic feet) 3a. Is the 36 hour demand greater than or equal to the DCV? Yes / No 3b. Is the 36 hour demand greater than 0.25DCV but less than the full DCV? Yes / No 3c. Is the 36 hour demand less than 0.25DCV? Yes 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. Harvest and use may be feasible. Conduct more detailed evaluation and sizing calculations to determine feasibility. Harvest and use may only be able to be 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. Harvest and use is considered to be infeasible. Is harvest and use feasible based on further evaluation? Yes, refer to Appendix E to select and size harvest and use BMPs. No, select alternate BMPs. □ □ □ c::> ~ ~ i i Appendix I: Forms and Checklists I-3 February 26, 2016 Categorization of Infiltration Feasibility Condition Form I-8 Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated? Note that it is not necessary to investigate each and every criterion in the worksheet if infiltration is precluded. Instead a letter of justification from a geotechnical professional familiar with the local conditions substantiating any geotechnical issues will be required. Criteria Screening Question Yes No 1 Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. Appendix I: Forms and Checklists I-4 February 26, 2016 Form I-8 Page 2 of 4 Criteria Screening Question Yes No 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. Part 1 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 *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings Appendix I: Forms and Checklists I-5 February 26, 2016 Form I-8 Page 3 of 4 Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Appendix I: Forms and Checklists I-6 February 26, 2016 Form I-8 Page 4 of 4 Criteria Screening Question Yes No 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Part 2 Result* If all answers from row 1-4 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. 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. *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings Appendix I: Forms and Checklists I-3 February 26, 2016 Categorization of Infiltration Feasibility Condition Form I-8 Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated? Note that it is not necessary to investigate each and every criterion in the worksheet if infiltration is precluded. Instead a letter of justification from a geotechnical professional familiar with the local conditions substantiating any geotechnical issues will be required. Criteria Screening Question Yes No 1 Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. Appendix I: Forms and Checklists I-4 February 26, 2016 Form I-8 Page 2 of 4 Criteria Screening Question Yes No 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. Part 1 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 *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings Appendix I: Forms and Checklists I-5 February 26, 2016 Form I-8 Page 3 of 4 Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Appendix I: Forms and Checklists I-6 February 26, 2016 Form I-8 Page 4 of 4 Criteria Screening Question Yes No 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 must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question must be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Part 2 Result* If all answers from row 1-4 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. 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. *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings BMP-1 BMP-2 BMP-3 Units Tributary area 5.47 0.47 0.10 acres Adjusted runoff factor for drainage area 0.56 0.74 0.8 85th percentile, 24-hr storm even rainfall depth 0.58 0.58 0.58 inches 1 Remaining DCV after implementiong retention BMPs1 6,449 732 168 cubic-feet 2 Infiltration rate if partial infiltration is feasible - - - in/hr. 3 Allowable drawdown time for aggregate stoarage below the undredrain 36 36 36 hours 4 Depth of runoff that can be infiltrated [Line 2 x Line 3]- - - inches 5 Aggregate pore space 0.40 0.40 0.40 in/in 6 Required depth of gravel below the underdrain [Line 4 x Line 5]- - - inches 7 Assumed surface area of the biofiltration BMP 2,825 915 240 sq-ft 8 Media retained pore space 0.1 0.1 0.1 in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 423.75 137.25 36.00 cubic-feet 10 DCV that requires biofiltration [Line 1- Line 9]6,026 595 132 cubic-feet 11 Surface Ponding (6"-12")24 12 12 inches 12 Media Thickness (18" min) Add mulch layer thickness 18 18 18 inches 13 Aggregate Storage above underdrain invert (12" typ)2 21 9 9 inches 14 Freely drained pore storage 0.2 0.2 0.2 in/in 15 Media filtration rate to be used for sizing 0.37 0.05 0.01 in/hr. 16 Allowable Routing Time for sizing 6 6 6 hours 17 Depth filtered during storm [Line 15 x Line 16]2.22 0.30 0.06 inches 18 Depth of Detention Storage [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]36.00 19.20 19.20 inches 19 Total Depth Treated [Line 17 + Line 18]38.22 19.50 19.26 inches 20 Required biofiltered volume [1.5 x Line 10]9,038 893 199 cubic-feet 21 Required Footprint [Line 20/ Line 19] x 12 2,838 549 124 sq-ft 22 Required Storage (surface + pores) Volume [0.75 x Line 10]4,519 446 99 cubic-feet 23 Required Footprint [Line 22/ Line 18] x 12 1,506 279 62 sq-ft 24 Area draining to the BMP 238,274 20,473 4,356 sq-ft 25 Adjusted Runoff Factor for drainage area 0.56 0.74 0.80 27 Minimum BMP Footprint [Line 24x Line 25 x 0.03]3 4,003 455 105 sq-ft 28 Footprint of the BMP= Maxium (Minimum(Line 21, 23), Line 27)4,003 455 105 sq-ft 1 DCV Calculated per Appendix B, Section B.1 of Carlsbad BMP Manual: C=___ (Runoff factor per Section B.1.1. Please see DMA Exhibit in Attachment 1a for C calculations) d=0.58 (85th Percentile, 24-hr storm depth in inches) A=___ (Tributary Area in Acres) 2 Aggregate storage above underdrain does not include the 6" choker stone layer DCV=3630 x C x d x A, where: 3 BMP-1 has been sized with an alternative footprint, by utilizing County of San Diego Automated Stormwater Pollutant Control Worksheets B.1- B.4 . For footprints less than 3%, Version 2.0 of the County Worksheets no longer provide an alternative minimum footprint ratio, and instead provide a BMP maintenance interval based on the proposed BMP size (given that the BMP is meeting all other stormwater requirements). Please see Worksheet B.4 in SWQMP Attachment 1e for supporting calculations. Option 1 - Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Footprint of the BMP Baseline Calculations Attachment 1e Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.5-1 Simple Sizing Method for Biofiltration BMPs Simple Sizing Method for Biofiltration BMPS Partial Retention BMP Parameters Page 1 of 1