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Home My WebLink AboutCT 2018-0003; MAGNOLIA BRADY; STORM WATER QUALITY MANAGEMENT PLAN; 2024-09-24CITY OF CARLSBAD PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) FOR YOUNG RESIDENCE ADDENDUM TO MAGNOLIA-BRADY (PROJECT ID: GR2018-0047 / GR2019-0021) [PROJECT ID (CBR2024-1521)] [DRAWING No. (DWG ENGINEER OF WORK: ____________________________________ 9-24-24_______David Caron, RCE No. 70066 Date PREPARED FOR: Arti Amin and Greg Young 1657 Brady Circle Carlsbad, CA 92008 949-412-5432 PREPARED BY: Civil Landworks Corporation 110 Copperwood Way Suite P, Oceanside CA, USA 92058 760-908-8745 DATE:September 23, 2024 E-35 REV 04/23 STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) TEMPLATE E-35 (FOR PDP PROJECTS ONLY) D evelopm ent Services Land Development Engineering 1635 Faraday Avenue 442-339-2750 www.carlsbadca.gov CT 2018-0003 _ City of Carlsbad TABLE OF CONTENTS SECTION 1. PROJECT DESCRIPTION ........................................................................................................ 1 2. SITE ANALYSIS ...................................................................................................................... 1 2.1 Drainage Patterns .................................................................................................................. 1 2.2 Design Assumptions ............................................................................................................. 1 3. SUMMARY AND CONCLUSIONS ......................................................................................... 1 Attachments Attachment 1: PDP Pollutant Control BMPs Attachment 1a: DMA Exhibit Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Pollutant Control BMP Design Worksheets / Calculations Attachment 2: Approved Storm Water Quality Management Plan 1. PROJECT DESCRIPTION The purpose of this addendum is to analyze the effect that the proposed improvement will have on the existing BMP system on the approved Storm Water Quality Management Plan Title Magnolia-Brady Dated August 27, 2019. The current owner of Lot 1 of the Magnolia-Brady development, located at 1657 Brady Circle, is proposing to install a pool in the back yard. All existing drainage patterns and storm water facilities as shown on the approved plans and reports are to remain. 2. SITE ANALYSIS 2.1 Drainage Patterns The existing site topography of Lot 1 sheet flows east into multiple basin inlets which conveys the stormwater south towards a shared BMP bioretention basins which the other 6 lots. This addendum study will include removing landscape area in the back of Lot 1 to construct a pool with associated hardscape. The additional impervious areas will be analyzed to verify if the existing bioretention basin has sufficient design capture volume to accommodate the proposed improvements. The final point of discharge will remain the same as before, exiting the site through storm pipe and discharging to an existing storm system on Brady Circle. 2.2 Design Assumptions The project site discharges directly into an exempt underground storm drainage system. Therefore, hydromodification analysis is not required for this project. The following are design criteria and assumption for the storm water treatment calculations. • City BMP sizing spreadsheet was used • Hydrologic Soil Type “B” and “D” • 85th Percentile Rainfall Depth = 0.6 3. SUMMARY AND CONCLUSIONS This addendum was created to supplement an approved Storm Water Quality Management Plan for Lot 1 of Magnolia-Brady development in Carlsbad, California. The addendum was provided to reflect the change in impervious areas. The proposed new impervious areas will drain into an existing approved bioretention basin, which serves as treatment BMP and detention for hydrology. Current site drainage management areas have been updated, and Lot 1 impervious surfaces have been revised to include the proposed improvements. The newly proposed impervious areas will be incorporated into the sizing of the bioretention basin. Lot 1 originally had 4,300 SF of impervious areas, now has been updated to 5,454 SF of impervious areas. Per the city BMP sizing spreadsheet, the current site requires a design capture volume of 1,674 cubic feet, which results in a minimum BMP footprint of 1,005 SF. The approved bioretention basin has a footprint of 1,150 SF, therefore the existing approved bioretention basin is sufficient in accepting the additional impervious surfaces created from Lot 1. Lot areas have been updated from the approved plan. Upon reviewing the drainage management exhibit, each lot drainage management area has been slightly adjusted based on the final layout onsite. The impervious areas remain the same on each lot, with the exception of Lot 1, which has been discussed above. The changes are from landscape areas changing to pervious pavement, or pervious pavement changing to landscape areas. The self mitigation or self retaining areas of each lot will remain unaffected for treatment purposes. Attachment 1a DMA Exhibit Page intentionally blank 110 COPPERWOOD WAY, SUITE P, OCEANSIDE, CA 92058 PH: 760-908-8745 ● info@civillandworks.com~ ~ V ---- - 3 1 /8" MIN. THICKNESS PA'l£RS W/ MIN. 3/8' VOID BEDDING COURSE -1.5" THICK OF 1/8" TO 3/8" (N0.8) AGGREGATE 6" CLASS 2 AGGREGATE VOID FILLER -1/8" TO 3/8" (NO. 8) AGGREGATE IN VOIDS • •. CONCRETE FOOTING MIN. 12" IN SUBGRADE ' 0.5' •. 3" PERFORATED PIPE SCH 40, PVC PIPE AT 1" ABO',£ SUBGRADE 4.5" SOIL SUBGRADE PERMEABLE PAVERS DETAIL OR EQUIVALENT N.T.S. r. 6" MIN. FREEBOARD 48.80FG 24"X24" OVERFLOW RISER 12" WATER SURFACE 6" MIN. FREEBOARD 7 149.0DFG \ -----:3~--::;~~Laz!!ll!ic!lJ:,j:..._ RIPRAP PER PLAN IMPERMEABLE LINER* MIRAFI 140N OR EQUIV. 148.30TG ORIFICE PLATE ( 4.6" ORIFICE) SEE DETAIL RIGHT •IMPERMEABLE LINER TO BE PLACED ALONG THE SIDES OF THE BIORETIENTION BASIN 1 r:; TIERRA TEXN0.3 FIL TIER BLANKET T = 2 BLANKETS IMPERMEABLE LINER* MIRAFI 140N OR EQUIV. 10" TOTAL OF 3/8" GRAVEL PERVIOUS MICROFILTER FABRIC AROUND GRAVEL MIRAFI 140N "FILTRATION' OR EQUIVALENT 12" SD OUTLET 144.971E ••BIORETENTION 'ENGINEERED SOIL?LAYER SHALL BE MINIMUM 18?DEEP \SANDY LOAM?SOIL MIX 'MTH NO MORE THAN 5% CLAY CONTENT. THE MIX SHALL CONTAIN 50-60% SAND, 20-30% COMPOST OR HARDWOOD MULCH, AND 20-30% TOPSOIL DETAIL 1: BIOFILTRATION WITH PARTIAL RETENTION BASIN NTS LOT SUMMARY LOT 1 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA {SF) ROOF/PAVEMENT/POOL 5,454 LANDSCAPE-B 0 LANDSCAPE-0 2,824 PERVIOUS PAYERS 298 LOT 2 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA {SF) ROOF /PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE-0 4,164 PERVIOUS PAYERS 106 LOT 3 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA {Sf) ROOF/PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE-0 3,977 PERVIOUS PAYERS 295 LOT 4 DRAINS TO BIOFIL TRA TION BASIN SURFACE TYPE AREA (Sf) ROOF/PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE -0 2,803 PERVIOUS PAYERS 111 LOT 5 -DRAINS TO BIOFILTRATION BASIN SURFACE TYPE AREA (SF) ROOF /PA'l£MENT 4,300 LANDSCAPE -B 0 LANDSCAPE -0 2,619 PERVIOUS PAYERS 295 LOT 1 -SELF MITIGATING / SELF RETAINING LOT 6 -DRAINS TO BIOFIL TRA TION BASIN SURFACE TYPE AREA (SF) SURFACE TYPE AREA (SF) PERVIOUS PA'l£MENT -SELF RETAINING 790 ROOF /PA'l£MENT 4,300 LANDSCAPE -SELF MITIGATING 1,364 LANDSCAPE-B 1,086 LANDSCAPE-0 1,722 PERVIOUS PA'l£RS 106 LOT 2 -SELF MITIGATING / SELF RETAINING LOT 7 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA (SF) SURFACE TYPE AREA (SF) PERVIOUS PA'l£MENT -SELF RETAINING 655 ROOF /PAVEMENT 4,300 LANDSCAPE -SELF MITIGATING 1,501 LANDSCAPE-B 2,436 LANDSCAPE-□ 706 PERVIOUS PA'l£RS 312 LOT 3 -SELF MITIGATING / SELF RETAINING LOT 8 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA (Sf) SURF ACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 790 ROOF /PA'l£MENT 0 LANDSCAPE -SELF MITIGATING 1,365 LANDSCAPE -B 4,522 LANDSCAPE -D 2,517 LOT 4 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 558 LANDSCAPE -SELF MITIGATING 1,227 LOT 5 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA {SF) PERVIOUS PA'i£MENT -SELF RETAINING 695 LANDSCAPE -SELF MITIGATING 1,090 ' I :❖ \ I t I I f, I LOT 6 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 558 LANDSCAPE -SELF MITIGATING 1,227 LOT 7 -SELF MITIGATING / SELF RETAINING SURFACE TYPE PERVIOUS PAVEMENT -SELF RETAINING LANDSCAPE -SELF MITIGATING 20 0 20 GRAPHIC SCALE SCALE: 1" = 20' AREA {Sf) 693 1,121 40 ATTACHMENT 1A OMA EXHIBIT LANDSCAPE LEGEND ITEM SUBDIVISION BOUNDARY DMA-AREA HYDROLOGIC SOIL GROUP LINE HARDSCAPE/ROOF DMA BOUNDARY BIOFIL TRA TION BASIN PERVIOUS PAVEMENT FLOW DIRECTION NOTE: SYMBOL DMA-X I ' ' • • 'I i i i i i --) 1. GROUNDWATER WAS NOT ENCOUNTER WITHIN 12 FEET OF BORING EXPLORATION PER PRELIMINARY GEOTECHNICAL EVALUATION BY GEOCON INC. 2. SITE SOIL TYPE INCLUDES TYPE 'B" AND TYPE "D' 3. SEE DMA SUMMARY IN ATTACHMENT 1 B OMA SUMMARY DMA ID Type DMA-1A Roof/Pm,ement DMA-18 Landscape-B DMA-1 C Landscape-D DMA-1 D Pervious pa'vt11ent TOTAL DMA ID Type DMA-2A Pervious Pavement -Self Retaining DMA-28 Landscape-Self Mitigating TOTAL DMA ID Type DMA-3A Pervious Pavement -Self Retaining DMA-38 Landscape-Self Mitigating TOTAL DMA ID Type DMA-4A Pervious Pavement -Self Retaining DMA-48 Landscape-Self Mitigating TOTAL □MAID DMA-5A DMA-58 TOTAL □MAID DMA-6A DMA-68 TOTAL Type Pervious Pavement -Self Retaining Landscape-Self Mitigating Type Pervious Pavement -Self Retaining Landscape-Self Mitigating DMA ID Type DMA-7 A Pervious Pavement -Self Retaining DMA-78 Landscape-Self Mitigating TOTAL DMA ID Type DMA-8A Per.ious Pa..,ment -Self Retaining DMA-88 Landscape-Self Mitigating TOTAL Total Area SF 31,254 8,044 22,486 1,523 63,307 Total Area SF 790 1,364 2,154 Total Area SF 655 1,501 2,156 Total Area SF 790 1,365 2,155 Total Area SF 558 1,227 1,785 Total Area SF 695 1,090 1,785 Total Area SF 558 1,227 1,785 Total Area SF 693 1,121 1,814 Total Area Acres 0.717 0.185 0.516 0.035 1.453 Total Area Acres 0.018 0.031 0.049 Total Area Acres 0,015 0.034 0.049 Total Area Acres 0.018 0.031 0.049 Total Area Acres 0.013 0.028 0.041 Total Area Acres 0.016 0.025 0.041 Total Area Acres 0.013 0.028 0.041 Total Area Acres 0.016 0.026 0.042 °'~---------------------------------------------------------------------------------------------------------------------------------------------------~ Page intentionally blank Attachment 1b Tabular Summary of DMAs and Design Capture Volumes Page intentionally blank DMA SUMMARY DMA ID Type Total Area Total Area SF Acres DMA-1A Roof/Pavement 31,254 0.717 DMA-1B Landscape-B 8,044 0.185 DMA-1C Landscape-D 21,332 0.490 DMA-1D Pervious pavment 1,523 0.035 TOTAL 62,153 1.427 DMA ID Type Total Area Total AreaSFAcres DMA-2A Pervious Pavement - Self Retaining 790 0.018 DMA-2B Landscape-Self Mitigating 1,364 0.031 TOTAL 2,154 0.049 DMA ID Type Total Area Total AreaSFAcres DMA-3A Pervious Pavement - Self Retaining 655 0.015 DMA-3B Landscape-Self Mitigating 1,501 0.034 TOTAL 2,156 0.049 DMA ID Type Total Area Total Area SF Acres DMA-4A Pervious Pavement - Self Retaining 790 0.018 DMA-4B Landscape-Self Mitigating 1,365 0.031 TOTAL 2,155 0.049 DMA ID Type Total Area Total AreaSFAcres DMA-5A Pervious Pavement - Self Retaining 558 0.013 DMA-5B Landscape-Self Mitigating 1,227 0.028 TOTAL 1,785 0.041 DMA ID Type Total Area Total Area SF Acres DMA-6A Pervious Pavement - Self Retaining 695 0.016 DMA-6B Landscape-Self Mitigating 1,090 0.025 TOTAL 1,785 0.041 DMA ID Type Total Area Total Area SF Acres DMA-7A Pervious Pavement - Self Retaining 558 0.013 DMA-7B Landscape-Self Mitigating 1,227 0.028 TOTAL 1,785 0.041 DMA ID Type Total Area Total AreaSFAcres DMA-8A Pervious Pavement - Self Retaining 693 0.016 DMA-8B Landscape-Self Mitigating 1,121 0.026 TOTAL 1,814 0.042 Attachment 1c Pollution Control BMP Design Worksheets / Calculations Page intentionally blank Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1 DCV - DMA-1 185th percentile 24-hr storm depth from Figure B.1-1 d=0.6 inches 2 Area tributary to BMP (s)A=1.427 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.54 unitless 4 Tree wells volume reduction TCV=0 cubic-feet 5 Rain barrels volume reduction RCV=0 cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=1,674 cubic-feet Storm Water Standards January 2016 Edition B-10 Design Capture Volume Worksheet B.2-1 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs - DMA-1 1 1,674 cubic- feet 2 0.09 in/hr. 3 36 hours 4 3.24 inches 5 0.40 in/in 6 8.1 inches 7 1200 sq-ft 8 0.1 in/in 9 504 cubic- feet 10 1,170 cubic- feet 11 12 inches 12 18 inches 13 3 inches 14 0.2 in/in 15 5.00 in/hr. 16 6 hours 17 30.00 inches 18 16.8 inches 19 46.80 inches 20 1755.58 cubic- feet 21 450 sq-ft 22 877.78875 cubic- feet 23 627 sq-ft 24 62,153 sq-ft 25 0.54 26 1,005 sq-ft 27 1,150 sq-ft Allowable drawdown time for aggregate storage below the underdrain Depth of runoff that can be infiltrated [Line 2 x Line 3] Aggregate pore space Required depth of gravel below the underdrain [Line 4/ Line 5] Assumed surface area of the biofiltration BMP Option 1 – Biofilter "1.5" times the DCV Media retained pore storage Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 DCV that requires biofiltration [Line 1 – Line 9] BMP Parameters Surface Ponding [6 inch minimum, 12 inch maximum] Allowable Routing Time for sizing Depth filtered during storm [ Line 15 x Line 16] Depth of Detention Storage [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] Total Depth Treated [Line 17 + Line 18] Media Thickness [18 inches minimum], also add mulch layer thickness to this line for sizing calculations Aggregate Storage above underdrain invert (12 inches typical) – use 0 inches for sizing if the aggregate is not over the entire bottom surface area Media available pore space Media filtration rate to be used for sizing (5 in/hr. with no outlet control; if the filtration is controlled by the outlet, use the outlet controlled rate) Baseline Calculations Simple Sizing Method for Biofiltration BMPs Worksheet B.5-1 Remaining DCV after implementing retention BMPs Partial Retention Infiltration rate from Form I-9 if partial infiltration is feasible Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x 0.03] Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Option 2 - Store 0.75 of remaining DCV in pores and ponding Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 Footprint of the BMP I Attachment 2 Approved Storm Water Quality Management Plan Page intentionally blank CITY OF CARLSBAD PRIORITY DEVELOPMENT PROJECT (PDP) FINAL STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) FOR Magnolia-Brady PROJECT ID: GR2018-0047 / GR2019-0021 DWG 515-3A / 515-3B ENGINEER OF WORK: ____________________________________________ David Caron, RCE No. 70066 Date PREPARED FOR: Magnolia A3, LLC 5 Hoya Street Rancho Mission Viejo, CA 92694 (914) 584-2041 PREPARED BY: Civil Landworks Corporation 110 Copperwood Way Suite P, Oceanside CA, USA 92058 760-908-8745 DATE: August 27, 2019 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 Attachment 1b: 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 1e: 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 CERTIFICATION PAGE Project Name: Magnolia-Brady Project ID: CT2018-0003 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. ________________________________________________________ Engineer of Work's Signature, RCE No. 70066, Exp 9-30-20 David Caron______________________________________________ Print Name Civil Landworks Corp.______________________________________ Company ____________________________ Date PROJECT VICINITY MAP I S ITE V IC I N ITY MAP MAGNOLIA AVE City’s Storm Water Standard Questionnaire (Form E-34) 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. 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and other vehicles. ,V\RXUSURMHFWDQHZRUUHGHYHORSPHQWSURMHFWWKDWFUHDWHVDQGRUUHSODFHVVTXDUHIHHWRUPRUH RILPSHUYLRXVVXUIDFHFROOHFWLYHO\RYHUWKHHQWLUHVLWHDQGGLVFKDUJHVGLUHFWO\WRDQ(QYLURQPHQWDOO\ 6HQVLWLYH$UHD(6$"“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). ,V\RXUSURMHFWDQHZGHYHORSPHQWRUUHGHYHORSPHQWSURMHFWWKDWFUHDWHVDQGRUUHSODFHVVTXDUH IHHWRUPRUHRILPSHUYLRXVVXUIDFHWKDWVXSSRUWVDQDXWRPRWLYHUHSDLUVKRS"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. ,V\RXUSURMHFWDQHZGHYHORSPHQWRUUHGHYHORSPHQWSURMHFWWKDWFUHDWHVDQGRUUHSODFHVVTXDUH IHHWRUPRUHRILPSHUYLRXVDUHDWKDWVXSSRUWVDUHWDLOJDVROLQHRXWOHW5*2"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. ,V\RXUSURMHFWDQHZRUUHGHYHORSPHQWSURMHFWWKDWUHVXOWVLQWKHGLVWXUEDQFHRIRQHRUPRUHDFUHVRIODQG DQGDUHH[SHFWHGWRJHQHUDWHSROOXWDQWVSRVWFRQVWUXFWLRQ" ,V\RXUSURMHFWORFDWHGZLWKLQIHHWRIWKH3DFLILF2FHDQDQGFUHDWHVVTXDUHIHHWRUPRUHRI LPSHUYLRXVVXUIDFHRU LQFUHDVHVLPSHUYLRXVVXUIDFHRQWKHSURSHUW\E\PRUHWKDQ"&0& ,I\RXDQVZHUHG³\HV´WRRQHRUPRUHRIWKHDERYHTXHVWLRQV\RXUSURMHFWLVDPDP,I\RXUSURMHFWLVDUHGHYHORSPHQW SURMHFWgo to step 4,I\RXUSURMHFWLVDQHZSURMHFWgo to step 5,FKHFNWKHILUVWER[VWDWLQJ³0\SURMHFWLVD PDP«´ DQGFRPSOHWHDSSOLFDQWLQIRUPDWLRQ ,I\RXDQVZHUHG³QR´WRDOORIWKHDERYHTXHVWLRQV\RXUSURMHFWLVDµSTANDARD PROJECT.¶Go to step 5FKHFNWKH VHFRQGER[VWDWLQJ³0\SURMHFWLVDµ67$1'$5'352-(&7¶«´DQGFRPSOHWHDSSOLFDQWLQIRUPDWLRQ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ 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 IrnpervIous calculation below: Existing impervious area {A)= 5,o31 sq. ft. □ [lJ Total proposed newly created or replaced ImpervIous area (8) = 30 100 sq. ft. Percent impervious area created or replaced (B/A}*100 = 636 % 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 statinQ ~~ project is a PDP ... " and comelete applicant information. STEP5 CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION !Z) 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. □ My project is a 'ST ANOARD 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· !A'!)utt{_ j);')tc{ /V f/20V/;_ 1 ~pplicant Title: ~ Applicant Sig~re. ~~ ~ Date 7/>/lr- • Environmentally Sens,!1ve Areas include but are not limited to all Clean Water Act Section 303td) 1mpa1red water bodies, areas designated as Areas of Special B1oiogical Significance by the State Water Resources Control Board (\Nater Qual:ty Comrol Plan for the San Diego Basin (1994) and amendmems), wat,,r bodies designated with the RAHE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments), areas designated as preseIves or their equivalent under the Multi Species Conservation Program within the Cities and Counly of San o;ego Habitat Management P!an and any other equivalent enviro,imentally sens:tIve areas ,vh1ch have been 1de11t1fied by the City This Box for C1tv Use Only YES NO City Concurrence: □ □ By: Date. Pro;ect ID : E.-34 Page 4 of4 REV 02/16 SITE INFORMATION CHECKLIST Project Summary Information Project Name Magnolia-Brady Project ID CT2018-0003 Project Address Brady Circle Carlsbad, California 92008 Assessor's Parcel Number(s) (APN(s)) 205-220-15 and 205-220-16 Project Watershed (Hydrologic Unit) Carlsbad 904 – Encinas 904.4 Parcel Area _1.740___ Acres (_75,786______ Square Feet) Existing Impervious Area (subset of Parcel Area) _0.115___ Acres (_5,031______ Square Feet) Area to be disturbed by the project (Project Area) _1.915___ Acres (_83,417____ Square Feet) Project Proposed Impervious Area (subset of Project Area) _0.691___ Acres (_30,100______ Square Feet) Project Proposed Pervious Area (subset of Project Area) _1.076___ Acres (_45,686______ Square Feet) Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the Project. This may be less than the Parcel Area. Description of Existing Site Condition and Drainage Patterns Current Status of the Site (select all that apply): ☒ Existing development Previously graded but not built out Agricultural or other non-impervious use Vacant, undeveloped/natural Description / Additional Information: Existing area consist of a single-family residence. Existing Land Cover Includes (select all that apply): ☒ Vegetative Cover ☒ Non-Vegetated Pervious Areas ☒ Impervious Areas Description / Additional Information: Existing site’s pervious area is covered with dirt, cobble, and grasses. Impervious area consists of building footprint and AC driveway. Underlying Soil belongs to Hydrologic Soil Group (select all that apply): NRCS Type A ☒ NRCS Type B NRCS Type C ☒ NRCS Type D Approximate Depth to Groundwater (GW): GW Depth < 5 feet 5 feet < GW Depth < 10 feet 10 feet < GW Depth < 20 feet ☒ GW Depth > 20 feet Existing Natural Hydrologic Features (select all that apply): Watercourses Seeps Springs Wetlands ☒ None Description / Additional Information: 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 site consists of a single-family residence with a partial paved AC driveway. The eastern portion of the site slopes westerly, and the northern portion of the site slopes southerly. All drainage onsite converges into an existing basin inlet at the middle of the site along the westerly property line. The basin inlet connects to an existing storm system on Brady Circle. There appears to be grading for the depression around the basin inlet. There is little offsite runon from the slopes belonging to the adjacent school property to the east of the site. Ultimately, all the stormwater onsite and runons from offsite are either captured via the basin inlets onsite then discharge to existing storm system on Brady Circle. The existing storm system empties into Agua Hedionda Lagoon which outlets to the Pacific Ocean. Description of Proposed Site Development and Drainage Patterns Project Description / Proposed Land Use and/or Activities: The proposed project will include subdividing the parcel into eight lots to construct seven single- family residences and one lot for storm water treatment and detention. List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features): The proposed impervious areas include building footprints and hardscape. List/describe proposed pervious features of the project (e.g., landscape areas): The proposed pervious areas include landscape areas, pervious pavement and a biofiltration basins. Does the project include grading and changes to site topography? ☒ Yes No Description / Additional Information: The project will change the existing slopes to create flat pads for the seven lots to incorporate the new buildings. However, the proposed site will minimize grading to the maximum extent possible to maintain similar topography and drainage as the existing condition. Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)? ☒ Yes No Description / Additional Information: The proposed development will maintain the same drainage pattern as the existing to the maximum extent possible. Drainage from all eight new lots will consolidate into one, where it will be treated and detained, then discharge into the existing storm system on Brady Circle. The front yard will be compose of landscaping and pervious pavement. The landscape, in the front of the residential lots and the pervious pavement will be considered self-retaining areas. Installation of brow ditches along the easterly property line will collect all offsite runons to prevent co-mingling with the onsite storm water. The offsite runons will be conveyed through the site via a proposed storm drain system and discharge to the existing storm system on Brady Circle. 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 Interior floor drains and elevator shaft sump pumps ☒ Interior parking garages Need for future indoor & structural pest control ☒ Landscape/Outdoor Pesticide Use ☐ Pools, spas, ponds, decorative fountains, and other water features ☐ Food service ☐ Refuse areas Industrial processes Outdoor storage of equipment or materials Vehicle and Equipment Cleaning Vehicle/Equipment Repair and Maintenance Fuel Dispensing Areas Loading Docks Fire Sprinkler Test Water ☐ Miscellaneous Drain or Wash Water ☐ Plazas, sidewalks, and parking lots 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): The storm water from the site and offsite runons will be captured via onsite basin inlet, then discharge to the existing public storm system on Brady Circle. The public storm system will discharge the storm water into Agua Hedionda Lagoon which outlet 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 Agua Hedionda Lagoon No Listings No Listings 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 Heavy Metals X X Organic Compounds X Trash & Debris X Oxygen Demanding Substances X Oil & Grease X Bacteria & Viruses X Pesticides X X Hydromodification Management Requirements Do hydromodification management requirements apply (see Section 1.6 of the BMP Design Manual)? ☐ 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): The project discharges into an existing storm drain system that outlets into Agua Hedionda Lagoon then the Pacific Ocean. The existing storm drain system is shown as an exempt system. See Attachment 2a for mapping of exempt areas. 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 ☒ 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: 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. The proposed project has one point of compliance located at the existing storm system on Brady Circle. All onsite storm water, after treatment and detention, and offsite runons will be directed toward this location. 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 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) 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. N/A 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. N/A 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: Magnolia-Brady CT2018-0003 DWG 515-3A ✔ ✔ ✔ No outdoor materials storage areas on proposed project. 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. ✔ No materials stored in outdoor work areas on project. ✔ No outdoor trash storage areas on project. ✔✔ ✔ ✔✔ ✔ ✔✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ On-ste storm drain inlets: Mark all inlets with the words "No Dumping! Flows to Bay" or similar. Interior parking garages: All interior floor drains will be plumbed to sanitary sewer. Landscape/Outdoor Pesticide Use: Use low irrigated or drought tolerant plants. □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ 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: ✔ ✔ ✔ Harvest and use is considered to be infeasible. See Appendix 1c for additional info. I ID ID ID ID ID ID ID ID ID 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. Harvest and use BMPs demand calculation are as follows: The estimate anticipated average wet season demand over a period of 36 hours. 3 (residents per home) x 7 (homes) x 9.3 (flushes per resident) = 195.3 gal or 26.1 cf. 2.8 (avg. evapotranspiration) x [(0.2 plant factor x 44,740 SF landscape area) / 90% irrigation efficiency] x 0.015 = 417 cf DCV per Worksheet B.2-1 = 1,660 cf. Is the 36-hour demand greater than or equal to the DCV? NO Is the 36-hour demand greater than 0.25DCV but less than the full DCV? NO Is the 36-hour demand less than 0.25DCV? YES Harvest and use is considered to be infeasible. The following are factors when considering retention or infiltration. According to the USGS web survey, the proposed development resides on soil Type “B” and Type “D”. Type “B” soil have moderate infiltration rates when thoroughly wet, while Type “D” soil have poor infiltration rates when thoroughly wet. The majority of the site sits on Type “D” soil. Per the Geotechnical Investigation performed by Geocon Inc. dated January 17, 2018, infiltration rates of 0.07 and 0.32 inches/hour were found on site, averaging to 0.20 inches/hour. Using a factor safety of 2, a recommended average infiltration rate of 0.10 infiltration rate can be used for the site. Due to the low infiltration rates, infiltration BMP are deemed infeasible for the proposed development. Per Table D.5-1 City of Carlsbad BMPDM, a factor of safety was calculated to be 2.19. The site, which resulted in an infiltration rate of 0.09 inches/hour. Due to such low infiltration rates, full infiltration basin is deemed infeasible. Biofiltration basin was chosen for this project. Since there is some appreciable rate of infiltration, the bottom of the biofiltration basins will be unlined. All site drainage will surface flow toward the biofiltration basins. The biofiltration basins will be equipped with a flow control structure that will allow for infiltration, treatment and detention during smaller storm event, while allowing larger storm events to bypass and discharge into the existing storm water system on Brady Circle. Permeable pavement for DMA -2A, 3A, 4A, 5A, 6A, and 7A are considered self-retaining permeable pavement per SW Section 5.2.3 and SD-6B. Therefore no DCV will be treated. 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 __515-3A____ Sheet No. __2________ 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) ☐ 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 ☐ Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP Other (describe in discussion section below) Discussion (as needed): Per BMP spreadsheet, the drawdown time of the surface has been met to comply with the DEH drawdown guidelines for vector control. 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 __515-3A____ Sheet No. __4,5________ 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) ☐ 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 ☐ Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP ☐ Other (describe in discussion section below) Discussion (as needed): Pervious pavers for driveways and walkways will be constructed for this project. Pervious pavers will be for pollutant control only. Attachment 1 BACKUP FOR PDP POLLUTANT CONTROL BMPS 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 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 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) Attachment 1a DMA Exhibit 110 COPPERWOOD WAY, SUITE P, OCEANSIDE, CA 92058 PH: 760-908-8745 ● info@civillandworks.com.,, ~ 20 APPROVED PERVIOUS PAVERS W/ MIN, 3/8" VOID BEDDING COURSE - 1.5" THICK OF 1/8" TO 3/8" (N0.8) AGGREGATIE 0 20 GRAPHIC SCALE SCALE: 1"= 20' 40 VOID FILLER -1/8" TO 3/8" (NO. 8) AGGREGA TIE IN VOIDS • CONCRETIE FOOTING MIN. 6" IN SUBGRADE r. 6" MIN. FREEBOARD 48,80FG 6" CLASS 2 AGGREGATIE 3" PERFORATED PIPE SCH 40, PVC 1: 1 EXCAVATIED SLOPE PIPE AT 1' ABOVE SUBGRADE SOIL SUBGRADE PERMEABLE PAVERS DETAIL OR EQUIVALENT N.T.S. MIN. 18" MEDIA ••WITH MIN. 5 IN/HR FILTRATION RATIE 3' OF 3/8' GRAVEL UNDER PERFORATIED PIPE 24"X24" OVERFLOW RISER 12" WA TIER SURFACE 11 rn rn TTT=ill, I 6" PERFORATED PIPE EXISTING UNCOMPACTIED SOILS ORIFICE PLA TIE ( 4.6" ORIFICE) SEE DETAIL RIGHT IMPERMEABLE LINER• MIRAFI 140N OR EQUIV. RIPRAP PER PLAN 10" TOTAL OF 3/8" GRAVEL PERVIOUS MICROFIL TIER FABRIC AROUND GRAVEL MIRAFI 140N 'FILTRATION" OR EQUIVALENT 12" SD OUTLET 144.97lE Civil D d k *IMPERMEABLE LINER TO BE PLACED ALONG THE SIDES OF THE BIORETIENTION BASIN an WO r S ••BIORETIENTION 'ENGINEERED SOIL?LAYER SHALL BE MINIMUM 18?DEEP \SANDY LOAM?SOIL MIX WITH NO MORE THAN 5% CLAY CONTIENT. THE MIX SHALL CONTAIN 50-60% SAND, 20-30% COMPOST OR HARDWOOD MULCH, AND 20-30% TOPSOIL. DETAIL 1: BIOFILTRA TION WITH -PARTIAL RETENTION BASIN NTS LOT SUMMARY LOT 1 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA (SF) ROOF/PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE-D 4,065 PERVIOUS PAVERS 450 LOT 2 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA (SF) ROOF /PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE-D 4,249 PERVIOUS PAVERS 262 LOT 3 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA {SF) ROOF /PAVEMENT 4,300 LANDSCAPE -B 0 LANDSCAPE-D 4,097 PERVIOUS PAVERS 414 LOT 4 DRAINS TO BIOFIL TRA TION BASIN SURFACE TYPE AREA (SF) ROOF /PAVEMENT 4,300 LANDSCAPE -B 0 LANDSCAPE -D 2,892 PERVIOUS PA VERS 263 LOT 5 -DRAINS TO BIOFILTRATION BASIN SURFACE TYPE AREA (SF) ROOF /PAVEMENT 4,300 LANDSCAPE-B 0 LANDSCAPE-D 2,710 PERVIOUS PAVERS 445 LOT 1 -SELF MITIGATING / SELF RETAINING LOT 6 -DRAINS TO BIOFIL TRA TION BASIN SURFACE TYPE AREA (SF) SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 630 ROOF/PAVEMENT 4,300 LANDSCAPE -SELF MITIGATING 1,285 LANDSCAPE-B 1,086 LANDSCAPE-D 1,807 PERVIOUS PAYERS 262 LOT 2 -SELF MITIGATING / SELF RETAINING LOT 7 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA (SF) SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 496 ROOF /PAVEMENT 4,300 LANDSCAPE -SELF MITIGATING 1,419 LANDSCAPE-B 2,436 LANDSCAPE-D 1,096 PERVIOUS PAYERS 465 LOT 3 -SELF MITIGATING / SELF RETAINING LOT 8 -DRAINS TO BILFIL TRA TION BASIN SURFACE TYPE AREA {SF) SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 494 ROOF /PAVEMENT 0 LANDSCAPE -SELF MITIGATING 1,421 LANDSCAPE -B 4,522 LANDSCAPE-D 2,518 LOT 4 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 400 LANDSCAPE -SELF MITIGATING 1,144 LOT 5 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 405 LANDSCAPE -SELF MITIGATING 1,139 LOT 6 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PERVIOUS PAVEMENT -SELF RETAINING 400 LANDSCAPE -SELF MITIGATING 1,111 LOT 7 -SELF MITIGATING / SELF RETAINING SURFACE TYPE AREA (SF) PER'IIOUS PAVEMENT -SELF RETAINING 401 LANDSCAPE -SELF MITIGATING 1,774 ATTACHMENT 1A OMA EXHIBIT LANDSCAPE LEGEND ITEM SUBDIVISION BOUNDARY OMA-AREA HYDROLOGIC SOIL GROUP LINE HARDSCAPE/ROOF DMA BOUNDARY BIOFIL TRA TION BASIN PERVIOUS PAVEMENT FLOW DIRECTION NOTE: SYMBOL DMA-X I ' ' • • 'I i i i i i --) 1. GROUNDWATER WAS NOT ENCOUNTER WITHIN 12 FEET OF BORING EXPLORATION PER PRELIMINARY GEOTECHNICAL EVALUATION BY GEOCON INC. 2. SITE SOIL TYPE INCLUDES TYPE 'B" AND TYPE "D' 3. SEE DMA SUMMARY IN ATTACHMENT 1 B DMASUMMARY DMAID DMA-1A DMA-1B DMA-1C DMA-1D TOTAL Type Roof/Pa1..ement Landscape-B Landscape-D Pervious pa'ulllent DMA ID Type DMA-2A Pervious Pavement -Self Retaining DMA-2B Landscape-Self Mitigating TOTAL DMA ID Type DMA-3A Pervious Pa1.ement -Self Retaining DMA-3B Landscape-Self Mitigating TOTAL DMA ID Type DMA-4A Pervious Pa1.ement -Self Retaining DMA-4B Landscape-Self Mitigating TOTAL DMAID DMA-5A DMA-5B TOTAL DMAID DMA-6A DMA-6B TOTAL DMAID DMA-7A DMA-7B TOTAL Type Pervious Pa1.ement -Self Retaining Landscape-Self Mitigating Type Pervious Pa1.ement -Self Retaining Landscape-Self Mitigating Type Pervious Pa1.ement -Self Retaining Landscape-Self Mitigating DMA ID Type OMA-BA Pervious Pa1.ement -Self Retaining DMA-8B Landscape-Self Mitigating TOTAL Total Area Total Area SF Acres 30,100 8,044 20,872 2,562 61,578 Total Area SF 630 1,285 1,915 Total Area SF 496 1,419 1,915 Total Area SF 494 1,421 1,915 Total Area SF 400 1,144 1,544 Total Area SF 405 1,139 1,544 Total Area SF 400 1,144 1,544 Total Area SF 401 1,774 2,175 0.691 0.185 0.479 0.059 1.414 Total Area Acres 0.014 0.029 0.044 Total Area Acres 0.011 0.033 0.044 Total Area Acres 0.011 0.033 0.044 Total Area Acres 0.009 0 026 0.035 Total Area Acres 0.009 0.026 0.035 Total Area Acres 0.009 0.026 0.035 Total Area Acres 0.009 0.041 0.050 00~---------------------------------------------------------------------------------------------------------------------------------------------------~ Page intentionally blank Attachment 1b Tabular Summary of DMAs and Design Capture Volumes Page intentionally blank DMA SUMMARY DMA ID Type Total Area Total Area Runoff Factor C*A C Factor SF Acres DMA-1A Roof/Pavement 30,100 0.691 1.0 30,100 DMA-1B Landscape-B 8,044 0.185 0.1 804 DMA-1C Landscape-D 20,872 0.479 0.1 2,087 DMA-1D Pervious pavment 2,562 0.059 0.1 256 TOTAL 61,578 1.414 C=33,248 0.54 DMA ID Type Total Area Total Area Runoff Factor C*A C FactorSFAcres DMA-2A Pervious Pavement - Self Retaining 630 0.014 0.1 63 DMA-2B Landscape-Self Mitigating 1,285 0.029 0.1 129 TOTAL 1,915 0.044 C=192 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C FactorSFAcres DMA-3A Pervious Pavement - Self Retaining 496 0.011 0.1 50 DMA-3B Landscape-Self Mitigating 1,419 0.033 0.1 142 TOTAL 1,915 0.044 C=192 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C FactorSFAcres DMA-4A Pervious Pavement - Self Retaining 494 0.011 0.1 49 DMA-4B Landscape-Self Mitigating 1,421 0.033 0.1 142 TOTAL 1,915 0.044 C=192 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C Factor SF Acres DMA-5A Pervious Pavement - Self Retaining 400 0.009 0.1 40 DMA-5B Landscape-Self Mitigating 1,144 0.026 0.1 114 TOTAL 1,544 0.035 C=154 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C FactorSFAcres DMA-6A Pervious Pavement - Self Retaining 405 0.009 0.1 41 DMA-6B Landscape-Self Mitigating 1,139 0.026 0.1 114 TOTAL 1,544 0.035 C=154 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C Factor SF Acres DMA-7A Pervious Pavement - Self Retaining 400 0.009 0.1 40 DMA-7B Landscape-Self Mitigating 1,144 0.026 0.1 114 TOTAL 1,544 0.035 C=154 0.10 DMA ID Type Total Area Total Area Runoff Factor C*A C FactorSFAcres DMA-8A Pervious Pavement - Self Retaining 401 0.009 0.1 40 DMA-8B Landscape-Self Mitigating 1,774 0.041 0.1 177 TOTAL 2,175 0.050 C=218 0.10 Attachment 1c Harvest and Use Feasibility Screening Page intentionally blank Harvest and Use Feasibility Screening The estimate anticipated average wet season demand over a period of 36 hours. 3 (residents per home) x 7 (homes) x 9.3 (flushes per resident) = 195.3 gal or 26.1 cf. 2.8 (avg. evapotranspiration) x [(0.2 plant factor x 44,740 SF landscape area) / 90% irrigation efficiency] x 0.015 = 417 cf DCV per Worksheet B.2-1 = 1,660 cf. Is the 36-hour demand greater than or equal to the DCV? NO Is the 36-hour demand greater than 0.25DCV but less than the full DCV? NO Is the 36-hour demand less than 0.25DCV? YES Harvest and use is considered to be infeasible. Page intentionally blank Attachment 1d Form I-8, Categorization of Infiltration Feasibility Condition Page intentionally blank Appendix I: Forms and Checklists I-7 February 2016 Factor of Safety and Design Infiltration Rate Worksheet Form I-9 Factor Category Factor Description Assigned Weight (w) Factor Value (v) Product (p) p = w x v A Suitability Assessment Soil assessment methods 0.25 Predominant soil texture 0.25 Site soil variability 0.25 Depth to groundwater / impervious layer 0.25 Suitability Assessment Safety Factor, SA = p B Design Level of pretreatment/ expected sediment loads 0.5 Redundancy/resiliency 0.25 Compaction during construction 0.25 Design Safety Factor, SB = p Combined Safety Factor, Stotal= SA x SB Observed Infiltration Rate, inch/hr, Kobserved (corrected for test-specific bias) Design Infiltration Rate, in/hr, Kdesign = Kobserved / Stotal Supporting Data Briefly describe infiltration test and provide reference to test forms: GEOTECHNICAL INVESTIGATION 1534 MAGNOLIA AVENUE CARLSBAD, CALIFORNIA PREPARED FOR ASTHON 3, LLC RANCHO MISSION VIEJO, CALIFORNIA JANUARY 17, 2018 PROJECT NO. G2192-52-01 Project No. G2192-52-01 January 17, 2018 Ashton 3, LLC 5 Hoya Street Rancho Mission Viejo, California 92694 Attention: Mr. Taylor Ashton Subject: GEOTECHNICAL INVESTIGATION 1534 MAGNOLIA AVENUE CARLSBAD, CALIFORNIA Dear Mr. Ashton: In accordance with your request, we performed this geotechnical investigation for the proposed 7-lot residential development in Carlsbad, California. The accompanying report presents the results of our study and our conclusions and recommendations regarding the geotechnical aspects of project development. The results of our study indicate that the site can be developed as planned, provided the recommendations of this report are followed. Should you have questions regarding this report, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED Matthew R. Love RCE 84154 Shawn Foy Weedon GE 2714 John Hoobs CEG 1524 MRL:SFW:JH:dmc (e-mail) Addressee (3) Mr. Robert C. Ladwig GEOCON INCORPORATED GEOTECHNIC Al ■ ENVIRONMENTAL ■ MATERIALS ~ )lrJL 6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone 858.558.6900 ■ Fax 858.558.6159 TABLE OF CONTENTS 1. PURPOSE AND SCOPE ................................................................................................................. 1 2. SITE AND PROJECT DESCRIPTION ........................................................................................... 1 3. GEOLOGIC SETTING .................................................................................................................... 2 4. SOIL AND GEOLOGIC CONDITIONS ........................................................................................ 2 4.1 Undocumented Fill (Qudf) .................................................................................................... 2 4.2 Old Paralic Deposits (Qop) .................................................................................................... 2 5. GROUNDWATER .......................................................................................................................... 3 6. GEOLOGIC HAZARDS ................................................................................................................. 3 6.1 Faulting and Seismicity ......................................................................................................... 3 6.2 Ground Rupture ..................................................................................................................... 5 6.3 Liquefaction ........................................................................................................................... 5 6.4 Seiches and Tsunamis ............................................................................................................ 6 6.5 Landslides .............................................................................................................................. 6 7. CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 7 7.1 General ................................................................................................................................... 7 7.2 Excavation and Soil Characteristics ...................................................................................... 8 7.3 Grading .................................................................................................................................. 9 7.4 Temporary Excavations ....................................................................................................... 10 7.5 Seismic Design Criteria ....................................................................................................... 10 7.6 Shallow Foundations ........................................................................................................... 12 7.7 Concrete Slabs-on-Grade ..................................................................................................... 13 7.8 Post-Tensioned Foundation System Recommendations ...................................................... 14 7.9 Concrete Flatwork ............................................................................................................... 16 7.10 Retaining Walls ................................................................................................................... 17 7.11 Lateral Loading .................................................................................................................... 18 7.12 Preliminary Pavement Recommendations ........................................................................... 19 7.13 Site Drainage and Moisture Protection ................................................................................ 22 7.14 Grading, Improvement and Foundation Plan Review.......................................................... 22 LIMITATIONS AND UNIFORMITY OF CONDITIONS MAPS AND ILLUSTRATIONS Figure 1, Vicinity Map Figure 2, Geologic Map Figure 3, Wall/Column Footing Dimension Detail Figure 4, Typical Retaining Wall Drain Detail APPENDIX A FIELD INVESTIGATION Figures A-1 – A-9, Exploratory Trench Logs TABLE OF CONTENTS (Concluded) APPENDIX B LABORATORY TESTING Table B-I, Summary of Laboratory Maximum Density and Optimum Moisture Content Results Table B-II, Summary of Laboratory Direct Shear Results Table B-III, Summary of Laboratory Expansion Index Test Results Table B-IV, Summary of Laboratory Water-Soluble Sulfate Test Results Table B-V, Summary of Laboratory Resistance Value (R-Value) Test Results Figure B-1, Gradation Curves APPENDIX C STORM WATER MANAGEMENT INVESTIGATION APPENDIX D RECOMMENDED GRADING SPECIFICATIONS LIST OF REFERENCES APPENDIX C STORM WATER MANAGEMENT INVESTIGATION FOR 1534 MAGNOLIA AVENUE CARLSBAD, CALIFORNIA PROJECT NO. G2192-52-01 - C-1 - APPENDIX C STORM WATER MANAGEMENT INVESTIGATION We understand storm water management devices will be used in accordance with the BMP Design Manual currently used by the City of Carlsbad. If not properly constructed, there is a potential for distress to improvements and properties located hydrologically down gradient or adjacent to these devices. Factors such as the amount of water to be detained, its residence time, and soil permeability have an important effect on seepage transmission and the potential adverse impacts that may occur if the storm water management features are not properly designed and constructed. We have not performed a hydrogeological study at the site. If infiltration of storm water runoff occurs, downstream properties may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other undesirable impacts as a result of water infiltration. Hydrologic Soil Group The United States Department of Agriculture (USDA), Natural Resources Conservation Services, possesses general information regarding the existing soil conditions for areas within the United States. The USDA website also provides the Hydrologic Soil Group. Table C-I presents the descriptions of the hydrologic soil groups. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. In addition, the USDA website also provides an estimated saturated hydraulic conductivity for the existing soil. TABLE C-I HYDROLOGIC SOIL GROUP DEFINITIONS Soil Group Soil Group Definition A Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. B Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. C Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. D Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high-water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. The property is underlain by natural materials consisting of undocumented fill and Old Paralic Deposits and should be classified as Soil Group D. Table C-II presents the information from the - C-2 - USDA website for the subject property. The Hydrologic Soil Group Map, provided at the end of this appendix, presents output from the USDA website showing the limits of the soil units. TABLE C-II USDA WEB SOIL SURVEY – HYDROLOGIC SOIL GROUP Map Unit Name Map Unit Symbol Approximate Percentage of Property Hydrologic Soil Group kSAT of Most Limiting Layer (inches/hour) Chesterton-Urban Land Complex, 2 to 9 percent slopes CgC 83 D 0.00 – 0.06 Marina Loamy Coarse Sand, 2 to 9 percent slopes MlC 17 B 0.57 – 1.42 In-Situ Testing The infiltration rate, percolation rates and saturated hydraulic conductivity are different and have different meanings. Percolation rates tend to overestimate infiltration rates and saturated hydraulic conductivities by a factor of 10 or more. Table C-III describes the differences in the definitions. TABLE C-III SOIL PERMEABILITY DEFINITIONS Term Definition Infiltration Rate The observation of the flow of water through a material into the ground downward into a given soil structure under long term conditions. This is a function of layering of soil, density, pore space, discontinuities and initial moisture content. Percolation Rate The observation of the flow of water through a material into the ground downward and laterally into a given soil structure under long term conditions. This is a function of layering of soil, density, pore space, discontinuities and initial moisture content. Saturated Hydraulic Conductivity (kSAT, Permeability) The volume of water that will move in a porous medium under a hydraulic gradient through a unit area. This is a function of density, structure, stratification, fines content and discontinuities. It is also a function of the properties of the liquid as well as of the porous medium. The degree of soil compaction or in-situ density has a significant impact on soil permeability and infiltration. Based on our experience and other studies we performed, an increase in compaction results in a decrease in soil permeability. We performed 2 percolation tests within Trenches T-2 and T-3 at the locations shown on the attached Geologic Map, Figure 2. The results of the tests provide parameters regarding the percolation rate and - C-3 - the saturated hydraulic conductivity/infiltration characteristics of on-site soil and geologic units. Table C-IV presents the results of the estimated field saturated hydraulic conductivity and estimated infiltration rates obtained from the percolation tests. The calculation sheets are attached herein. We used a factor of safety applied to the test results on the worksheet values. The designer of storm water devices should apply an appropriate factor of safety. Soil infiltration rates from in-situ tests can vary significantly from one location to another due to the heterogeneous characteristics inherent to most soil. Based on a discussion in the County of Riverside Design Handbook for Low Impact Development Best Management Practices, the infiltration rate should be considered equal to the saturated hydraulic conductivity rate. TABLE C-IV FIELD PERMEAMETER INFILTRATION TEST RESULTS Test Location Test Depth (feet) Geologic Unit Percolation Rate (minutes/inch) Field-Saturated Infiltration Rate, ksat (inch/hour) C.4-1 Worksheet Infiltration Rate1, ksat (inch/hour) P-1 (T-2) 6 Qop 187.5 0.07 0.04 P-2 (T-3) 6 Qop 106.0 0.32 0.16 Average: 146.8 0.20 0.10 1 Using a factor of safety of 2. Infiltration categories include full infiltration, partial infiltration and no infiltration. Table C-V presents the commonly accepted definitions of the potential infiltration categories based on the infiltration rates. TABLE C-V INFILTRATION CATEGORIES Infiltration Category Field Infiltration Rate, I (inches/hour) Factored Infiltration Rate1, I (inches/hour) Full Infiltration I > 1.0 I > 0.5 Partial Infiltration 0.10 < I < 1.0 0.05 < I < 0.5 No Infiltration (Infeasible) I < 0.10 I < 0.05 1 Using a Factor of Safety of 2. Groundwater Elevations We did not encounter groundwater or seepage during the site investigation. We expect groundwater exists at depths greater than 50 feet below existing grades. - C-4 - New or Existing Utilities Utilities will be constructed within the site boundaries. Full or partial infiltration should not be allowed in the areas of the utilities to help prevent potential damage/distress to improvements. Mitigation measures to prevent water from infiltrating the utilities consist of setbacks, installing cutoff walls around the utilities and installing subdrains and/or installing liners. The horizontal and vertical setbacks for infiltration devices should be a minimum of 10 feet and a 1:1 plane of 1 foot below the closest edge of the deepest adjacent utility, respectively. Existing and Planned Structures Existing residential and roadway structures exist adjacent to the site. Water should not be allowed to infiltrate in areas where it could affect the neighboring properties and existing adjacent structures, improvements and roadway. Mitigation for existing structures consists of not allowing water infiltration within a lateral distance of at least 10 feet from the new or existing foundations. Slopes Hazards Slopes are not currently planned or exist on the property that would be affected by potential infiltration locations. Therefore, infiltration in regards to slope concerns would be considered feasible. Storm Water Evaluation Narrative As discussed herein, the property consists of existing undocumented fill overlying Old Paralic Deposits (Qop). Water should not be allowed to infiltrate into the undocumented or compacted fill within the basins as it will allow for lateral migration to adjacent residences. We evaluated the infiltration rates within the Old Paralic Deposits within the proposed basin areas to help evaluate if infiltration is feasible. We performed the infiltration tests at location where the basins would be practical based on the topography of the property and discussions with the Client. We performed the percolation tests at the lower elevations of the property and adjacent to the existing storm drain system. Our in-place infiltration tests indicate an average of 0.10 inches/hour (including a factor of safety of 2); therefore, the site is considered feasible for partial infiltration. We do not expect geologic hazards to exist on the property. Therefore, partial infiltration may be considered feasible within the Old Paralic Deposits. Storm Water Management Devices Liners and subdrains should be incorporated into the design and construction of the planned storm water devices. The liners should be impermeable (e.g. High-density polyethylene, HDPE, with a - C-5 - thickness of about 30 mil or equivalent Polyvinyl Chloride, PVC) to prevent water migration. The subdrains should be perforated within the liner area, installed at the base and above the liner, be at least 3 inches in diameter and consist of Schedule 40 PVC pipe. The subdrains outside of the liner should consist of solid pipe. The penetration of the liners at the subdrains should be properly waterproofed. The subdrains should be connected to a proper outlet. The devices should also be installed in accordance with the manufacturer’s recommendations. Liners should be installed on the side walls of the proposed basins in accordance with a partial infiltration design. Storm Water Standard Worksheets The BMP Design Manual requests the geotechnical engineer complete the Categorization of Infiltration Feasibility Condition (Worksheet C.4-1 or I-8) worksheet information to help evaluate the potential for infiltration on the property. The attached Worksheet C.4-1 presents the completed information for the submittal process. The regional storm water standards also have a worksheet (Worksheet D.5-1 or Form I-9) that helps the project civil engineer estimate the factor of safety based on several factors. Table C-VI describes the suitability assessment input parameters related to the geotechnical engineering aspects for the factor of safety determination. TABLE C-VI SUITABILITY ASSESSMENT RELATED CONSIDERATIONS FOR INFILTRATION FACILITY SAFETY FACTORS Consideration High Concern – 3 Points Medium Concern – 2 Points Low Concern – 1 Point Assessment Methods Use of soil survey maps or simple texture analysis to estimate short-term infiltration rates. Use of well permeameter or borehole methods without accompanying continuous boring log. Relatively sparse testing with direct infiltration methods Use of well permeameter or borehole methods with accompanying continuous boring log. Direct measurement of infiltration area with localized infiltration measurement methods (e.g., Infiltrometer). Moderate spatial resolution Direct measurement with localized (i.e. small-scale) infiltration testing methods at relatively high resolution or use of extensive test pit infiltration measurement methods. Predominant Soil Texture Silty and clayey soils with significant fines Loamy soils Granular to slightly loamy soils Site Soil Variability Highly variable soils indicated from site assessment or unknown variability Soil boring/test pits indicate moderately homogenous soils Soil boring/test pits indicate relatively homogenous soils Depth to Groundwater/ Impervious Layer <5 feet below facility bottom 5-15 feet below facility bottom >15 feet below facility bottom - C-6 - Based on our geotechnical investigation and the previous table, Table C-VII presents the estimated factor values for the evaluation of the factor of safety. This table only presents the suitability assessment safety factor (Part A) of the worksheet. The project civil engineer should evaluate the safety factor for design (Part B) and use the combined safety factor for the design infiltration rate. TABLE C-VII FACTOR OF SAFETY WORKSHEET DESIGN VALUES – PART A1 Suitability Assessment Factor Category Assigned Weight (w) Factor Value (v) Product (p = w x v) Assessment Methods 0.25 2 0.50 Predominant Soil Texture 0.25 2 0.50 Site Soil Variability 0.25 2 0.50 Depth to Groundwater/ Impervious Layer 0.25 1 0.25 Suitability Assessment Safety Factor, SA = p 1.75 1 The project civil engineer should complete Worksheet D.5-1 or Form I-9 using the data on this table. Additional information is required to evaluate the design factor of safety. - C-7 - Categorization of Infiltration Feasibility Condition Worksheet C.4-1 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? 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. X Provide basis: Based on the USGS Soil Survey, the property possesses Hydrologic Soil Group D classifications. In addition, we encountered field infiltration rates of: T-2/P-1: 0.07 inches/hour (0.04 with a FOS of 2.0) T-3/P-2: 0.32 inches/hour (0.16 with a FOS of 2.0) This results in an average infiltration rate of 0.20 inches/hour (0.10 with an FOS of 2.0). 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X Provide basis: Undocumented fill and Old Paralic Deposits underlie the property. Water that would be allowed to infiltrate could migrate laterally outside of the property limits to the existing right-of-ways (located to the south and west) and toward existing and proposed structures (located to the north and east). However, we expect the basins would be setback a sufficient distance from the existing and proposed utilities and structures to help alleviate seepage and underground utility concerns. Additionally, the use of vertical cutoff walls or liners, as recommended herein, would prevent lateral migration of water. The bottom of the basins should expose Old Paralic Deposits. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. - C-8 - Worksheet C.4-1 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: We did not encounter groundwater during the drilling operations on the property. We anticipate that groundwater is present at depths of greater than 50 feet. Therefore, infiltration due to groundwater elevations would be considered feasible. Additionally, we understand that contaminated soil or groundwater has not been documented or identified at the property. Therefore, infiltration due to groundwater concerns would be considered feasible. 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: We do not expect full infiltration would cause water balance issues including change of ephemeral streams or discharge of contaminated water to surface waters. 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 Not Full 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 the City to substantiate findings. - C-9 - Worksheet C.4-1 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. X Provide basis: Based on the USGS Soil Survey, the property possesses Hydrologic Soil Group D classifications. In addition, we encountered field infiltration rates of: T-2/P-1: 0.07 inches/hour (0.04 with a FOS of 2.0) T-3/P-2: 0.32 inches/hour (0.16 with a FOS of 2.0) This results in an average infiltration rate of 0.20 inches/hour (0.10 with an FOS of 2.0). 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X Provide basis: Undocumented fill and Old Paralic Deposits underlie the property. Water that would be allowed to infiltrate could migrate laterally outside of the property limits to the existing right-of-ways (located to the south and west) and toward existing and proposed structures (located to the north and east). However, we expect the basins would be setback a sufficient distance from the existing and proposed utilities and structures to help alleviate seepage and underground utility concerns. Additionally, the use of vertical cutoff walls or liners, as recommended herein, would prevent lateral migration of water. The bottom of the basins should expose Old Paralic Deposits. 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. - C-10 - Worksheet C.4-1 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: We did not encounter groundwater during the drilling operations on the property. We anticipate that groundwater is present at depths of greater than 50 feet. Therefore, infiltration due to groundwater elevations would be considered feasible. Additionally, we understand that contaminated soil or groundwater has not been documented or identified at the property. Therefore, infiltration due to groundwater concerns would be considered feasible. 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 shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: We did not provide a study regarding water rights. However, these rights are not typical in the San Diego area. 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. Partial 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 the City to substantiate findings. Excavation Percolation Test Project Name:Date:9/27/2017 Project Number:By:JML Open-Pit Location: Test Hole Length (in.)14.0 Test Hole Width (in.)12.0 Test Hole Dia. (in.) Test Hole Depth (in.)10.5 Test Hole Area, A , (in.2)168.0 ∆t /∆D ∆v/∆t (Q/A)*60 Reading Time, t (min) Depth of Water, D (in.) ∆t (min) Cumulative Time, t (min) ∆D (in.) Wetted Area, Awet (in.2) Change in Volume, ∆v (in.3) Percolation Rate (min/in.) Flow Rate, Q (in.3/min) Infiltration Rate, I t (in./hr) 0.0 8.25 15.0 8.19 0.0 8.50 15.0 8.49 0.0 8.50 15.0 8.25 0.0 8.50 15.0 8.49 0.0 8.50 15.0 8.49 0.0 8.50 15.0 8.44 0.0 9.00 15.0 8.99 0.0 9.00 15.0 8.94 0.0 9.00 15.0 8.99 0.0 9.00 15.0 8.93 0.0 9.00 15.0 8.92 0.0 9.25 15.0 9.20 Percolation Rate (Minutes/Inch) =187.5 =0.07 2 15.00 1.68 1500.00 0.11 0.01 0.06 0.01 1534 Magnolia G2192-52-01 T-2 (P-1) 1 15.00 10.50 240.00 0.70 0.07595.38 609.74 or 15.00 30.00 3 15.00 42.00 60.00 2.80 0.28 4 15.00 1.68 1500.00 0.11 0.01 0.25 0.01 603.50 609.74 45.00 60.00 6 15.00 10.50 240.00 0.70 0.07 5 15.00 1.68 1500.00 0.11 0.010.01 0.06 609.74 608.38 75.00 90.00 8 15.00 10.50 240.00 0.70 0.07 7 15.00 1.68 1500.00 0.11 0.010.01 0.06 635.74 634.38 105.00 120.00 10 15.00 11.76 214.29 0.78 0.07 9 15.00 1.68 1500.00 0.11 0.010.01 0.07 634.18 635.74135.00 150.00 12 15.00 8.40 300.00 0.56 0.05 11 15.00 13.44 187.50 0.90 0.080.08 0.05 633.92 647.70 165.00 180.00 Soil Infiltration Rate (Inches/Hour) 14 13 0.00 0.50 1.00 1.50 2.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00 In f i l t r a t i o n R a t e (i n . / h r ) Time (min) ~GEOCON Excavation Percolation Test Project Name:Date:9/27/2017 Project Number:By:JML Open-Pit Location: Test Hole Length (in.)14.0 Test Hole Width (in.)12.0 Test Hole Dia. (in.) Test Hole Depth (in.)11.0 Test Hole Area, A , (in.2)168.0 ∆t /∆D ∆v/∆t (Q/A)*60 Reading Time, t (min) Depth of Water, D (in.) ∆t (min) Cumulative Time, t (min) ∆D (in.) Wetted Area, A wet (in.2) Change in Volume, ∆v (in.3) Percolation Rate (min/in.) Flow Rate, Q (in.3/min) Infiltration Rate, I t (in./hr) 0.0 8.50 15.0 8.00 0.0 8.50 15.0 8.44 0.0 8.50 15.0 8.38 0.0 8.50 15.0 8.49 0.0 8.50 15.0 8.00 0.0 8.19 15.0 8.00 0.0 8.50 15.0 8.06 0.0 8.50 15.0 8.44 0.0 8.75 15.0 8.44 0.0 8.75 15.0 8.25 0.0 8.25 15.0 8.19 Percolation Rate (Minutes/Inch) =106.0 =0.32 13 Soil Infiltration Rate (Inches/Hour) 240.00 0.70 0.07 12 11 15.00 165.00 0.06 595.38 10.50 14 10 15.00 150.00 0.50 610.00 84.00 30.00 5.60 0.55 9 15.00 135.00 0.31 614.88 52.50 48.00 3.50 0.34 34.29 4.90 0.49 8 15.00 120.00 0.06 608.38 10.50 240.00 7 15.00 105.00 0.44 598.63 73.50 0.70 0.07 6 15.00 90.00 0.19 588.88 31.50 80.00 2.10 0.21 5 15.00 75.00 0.50 597.00 84.00 30.00 5.60 0.56 4 15.00 60.00 0.01 609.74 1.68 1500.00 0.11 0.01 3 15.00 45.00 0.13 606.75 21.00 120.00 1.40 0.14 84.00 30.00 5.60 0.56 2 15.00 30.00 0.06 608.38 10.50 240.00 0.70 0.07 1534 Magnolia G2192-52-01 T-3 (P-2) or 1 15.00 15.00 0.50 597.00 0.00 0.50 1.00 1.50 2.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 In f i l t r a t i o n R a t e (i n . / h r ) Time (min) ~GEOCON t N NO SCALE HYDROLOGIC SOIL SURVEY GEOCON INCORPORATED GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS 6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121 -297 4 PHONE 858 558-6900 -FAX 858 558-6159 ML/CW DSK/GTYPD 1534 MAGNOLIA AVENUE CARLSBAD, CALIFORNIA DATE 01 -17 -2018 I PROJECT NO.G2192 -52 -01 I FIG. C-1 Plotted:01/17/2018 8:10AM I By:JONATHAN WILKINS I File Location:Y:\PROJECTS\G2192-52-011534 Magnolia Ave\DETAILS\G2192-52-01_HydrologicSoilSurvey.dwg Project No. G2192-52-01 January 30, 2019 Ashton 3, LLC 5 Hoya Street Rancho Mission Viejo, California 92694 Attention: Mr. Taylor Ashton Subject: RESPONSE TO CITY COMMENTS 1534 MAGNOLIA AVENUE CARLSBAD, CALIFORNIA References: 1. Geotechnical Investigation, 1534 Magnolia Avenue, Carlsbad, California, prepared by Geocon Incorporated, dated January 17, 2017 (Project No. G2192-52-01). 2. Preliminary Permeable Pavement Recommendations, 1534 Magnolia Avenue, Carlsbad, California, prepared by Geocon Incorporated, dated May 21, 2018 (Project No. G2192-52-01). 3. Grading Plans for Magnolia-Brady, 1534 Magnolia Avenue, Carlsbad, California, prepared by Civil Landworks, dated November 27, 2018 (Drawing No. 515-3A). 4. Grading Plans – Plancheck #1 for “Magnolia-Brady”, 1534 Magnolia Avenue, Carlsbad, California, prepared by City of Carlsbad, dated January 25, 2019 (City Project ID CT 2018-0003). Dear Mr. Ashton: We prepared this letter to address the referenced review comments provided by the City of Carlsbad for the subject development. The reviewer’s comments are listed herein with our response immediately following. Comment 1: Provide recommendations for permeable pavers. Response: We provided recommendations for permeable pavers in our letter dated May 21, 2018 for the proposed development (see Reference 2). A copy of that letter has been appended herein. Comment 2: Infiltration testing was conducted during outdated BMP layout. Provide a letter verifying infiltration design rate is still applicable. Response: Based on our review of the project plans and the information contained within the referenced geotechnical documents, we opine the plans and details have been GEOCON INCORPORATED GEOTECHNICAL ■ ENVIRONMENTAL ■ MATE RI ALS O 6960 Flanders Drive ■ San Diego, California 92121-297 4 ■ Telephone 858.558.6900 ■ Fax 858.558.6159 Project No. G2192-52-01 - 2 - January 30, 2019 prepared in substantial conformance with the recommendations presented in the referenced geotechnical reports. The recommendations and conclusions in the referenced investigation remain valid for the proposed improvements, including our recommendations regarding storm water BMP design. The design infiltration rate we provided in the geotechnical documents remains applicable for the design of the project. We limited our review to geotechnical aspects of project development and the review did not include other details on the referenced plans. Geocon Incorporated has no opinion regarding other details found on the referenced plans, structural or otherwise, that do not directly pertain to geotechnical aspects of site development. If you have any questions regarding this correspondence, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED Matt R. Love RCE 84154 Shawn Foy Weedon GE 2714 MRL:dmc Attachment: Preliminary Permeable Pavement Recommendations Letter, dated May 21, 2018 (e-mail) Addressee (e-mail) Mr. Dave Lother )iUL Attachment 1e Pollution Control BMP Design Worksheets / Calculations Page intentionally blank Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1 DCV - DMA-1 185th percentile 24-hr storm depth from Figure B.1-1 d=0.6 inches 2 Area tributary to BMP (s) A=1.452 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C=0.53 unitless 4 Tree wells volume reduction TCV=0 cubic-feet 5 Rain barrels volume reduction RCV=0 cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=1,676 cubic-feet Storm Water Standards January 2016 Edition B-10 Design Capture Volume Worksheet B.2-1 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs - DMA-1 1 1,676 cubic- feet 2 0.09 in/hr. 3 36 hours 4 3.24 inches 5 0.40 in/in 6 8.1 inches 7 1200 sq-ft 8 0.1 in/in 9 504 cubic- feet 10 1,172 cubic- feet 11 12 inches 12 18 inches 13 3 inches 14 0.2 in/in 15 5.00 in/hr. 16 6 hours 17 30.00 inches 18 16.8 inches 19 46.80 inches 20 1758.15 cubic- feet 21 451 sq-ft 22 879.07626 cubic- feet 23 628 sq-ft 24 63,234 sq-ft 25 0.53 26 1,005 sq-ft 27 1,150 sq-ft Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x 0.03] Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Option 2 - Store 0.75 of remaining DCV in pores and ponding Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 Footprint of the BMP Simple Sizing Method for Biofiltration BMPs Worksheet B.5-1 Remaining DCV after implementing retention BMPs Partial Retention Infiltration rate from Form I-9 if partial infiltration is feasible Option 1 – Biofilter "1.5" times the DCV Media retained pore storage Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 DCV that requires biofiltration [Line 1 – Line 9] BMP Parameters Surface Ponding [6 inch minimum, 12 inch maximum] Allowable Routing Time for sizing Depth filtered during storm [ Line 15 x Line 16] Depth of Detention Storage [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] Total Depth Treated [Line 17 + Line 18] Media Thickness [18 inches minimum], also add mulch layer thickness to this line for sizing calculations Aggregate Storage above underdrain invert (12 inches typical) – use 0 inches for sizing if the aggregate is not over the entire bottom surface area Media available pore space Media filtration rate to be used for sizing (5 in/hr. with no outlet control; if the filtration is controlled by the outlet, use the outlet controlled rate) Baseline Calculations Allowable drawdown time for aggregate storage below the underdrain Depth of runoff that can be infiltrated [Line 2 x Line 3] Aggregate pore space Required depth of gravel below the underdrain [Line 4/ Line 5] Assumed surface area of the biofiltration BMP I DRAW DOWN for Biofiltration Basin Infiltration rate 0.09 inches / hour Qout = AV = A acres * 43560 sf/Acre (infiltration rate in/hr) * 1ft/12in (1 hr/3600 sec) Orifice Flow: Q = C * A * sqrt(2gh) g= 32.20 sf/sec C= 0.60 Orifice-1 No. of openings 1 Elevation 100.67 diameter 4.6 inches 0.38 ft A= 0.12 sf Stage Storage Area of Effective Head Q cfs Q total Rate mediaWater Depth (ft)Volume (cf)Area (Ac.ft)Infiltration (ft)Q infilt.Orifice-1 Orifice-1 Q inf + Q orifice in/hr 100.00 0 0.000 N/A 0.000 N/A 0.00 0.000 0.00 102.50 47,150 1.082 1,150 0.002 1.64 0.71 0.714 27.19 103.83 120,443 2.765 1,150 0.002 2.97 0.96 0.960 36.56 Rate through Media = Q cfs * 12 in/ft * 3600 sec / hour / 1150 sf I 1- ------------ BLANK PAGE Attachment 2 BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES Page intentionally blank ATTACHMENT 2 BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES This is the cover sheet for Attachment 2. Indicate which Items are Included behind this cover sheet: Attachment Sequence Contents Checklist Attachment 2a Hydromodification Management Exhibit (Required) ☐ Included See Hydromodification Management Exhibit Checklist on the back of this Attachment cover sheet. Attachment 2b Management of Critical Coarse Sediment Yield Areas (WMAA Exhibit is required, additional analyses are optional) See Section 6.2 of the BMP Design Manual. ☒ Exhibit showing project drainage boundaries marked on WMAA Critical Coarse Sediment Yield Area Map (Required) Optional analyses for Critical Coarse Sediment Yield Area Determination 6.2.1 Verification of Geomorphic Landscape Units Onsite 6.2.2 Downstream Systems Sensitivity to Coarse Sediment 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite Attachment 2c Geomorphic Assessment of Receiving Channels (Optional) See Section 6.3.4 of the BMP Design Manual. ☒ Not performed Included Attachment 2d Flow Control Facility Design and Structural BMP Drawdown Calculations (Required) See Chapter 6 and Appendix G of the BMP Design Manual ☒ Included Use this checklist to ensure the required information has been included on the Hydromodification Management Exhibit: The Hydromodification Management 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 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 Point(s) of Compliance (POC) for Hydromodification Management Existing and proposed drainage boundary and drainage area to each POC (when necessary, create separate exhibits for pre-development and post-project conditions) Structural BMPs for hydromodification management (identify location, type of BMP, and size/detail) Attachment 2a Hydromodification Management Exhibit N/A Page intentionally blank CARLSBADCARLSBAD DELDELMARMAR ENCINITASENCINITAS ESCONDIDOESCONDIDO OCEANSIDEOCEANSIDE POWAYPOWAY S.D.S.D.COUNTYCOUNTY S.D.S.D.COUNTYCOUNTY S.D.S.D.COUNTYCOUNTY SANSANDIEGODIEGO SANSANMARCOSMARCOS VISTAVISTA S a n Marcos Cr e e k S a n t a M a r g a rita River Sa nMarcos C r e e k E s c o n d i d o C r e e k Ra t t l esnakeCree k Agua He dio n d a Creek S a n L u i s R e yRiver B u e n a Vist a C r e e k Lusardi Creek E n cinitas C re e k S a nt a Y sa b e l C r eek S a nDieguit o Rive r S an Diegu it oRiver Receiving Waters and Conveyance Systems Exemptfrom Hydromodification Management Requirements Exhibit Date: Sept. 8, 2014 Aerial Imagery Source: DigitalGlobe, 06/2012 NORTH Key Map (Not to Scale) Legend Municipal Boundaries Water Storage Reservoirs, Lakes,Enclosed Embayments, PacificOcean, Buena Vista Lagoon Reaches of San Luis Rey River, SanDieguito River, San Diego River,Forester Creek, Sweetwater River,Otay River 0 5 102.5 Miles Watershed Boundaries Regional WMAA Streams Exempt River Reaches: Existing underground storm drains orconveyance channels whose bedand bank are concrete-lined,discharging directly to exempt waterbodies, exempt rivers, or localizedareas of Agua Hedionda Lagoon andBatiquitos Lagoon Exempt Conveyance Systems: Exempt Bodies: Carlsbad Watershed Management AreaHU 904.00, 211 mi2 Wlloo.,,~ Ml1tnalti I emeeiJ Geosyntec t> consultants ,: SAN .J./<CIN'rO Mot!HrAINS Cah1,11la ln.d1111n FLuar,,at,an RICK ENGINEERING COMPANY 0co,~11-itr .... ~JC~la/ -1-• -, ' s.,1t Cil ,414 m ) '/ ! a Page intentionally blank Attachment 2b Management of Critical Coarse Sediment Yield Areas Page intentionally blank Page intentionally blank Attachment 2c Geomorphic Assessment of Receiving Channels N/A Page intentionally blank Attachment 2d Flow Control Facility Design N/A Page intentionally blank ATTACHMENT 3 Structural BMP Maintenance Thresholds and Actions Page intentionally blank Page 1 Operation and Maintenance Plan for the Stormwater Quality BMP Facilities for MAGNOLIA-BRADY – SWQMP May 2, 2019 I. PURPOSE The primary purpose of this Operations & Maintenance Plan (O&M Plan) shall be to provide a routine maintenance program that maintains the treatment facilities effectiveness. II. COVERAGE AREA This project will utilize 1 primary treatment facility type and a secondary treatment structure located on-site: 1. Biofiltration Basin – located along the easterly property line. 2. Pervious pavement – located in driveways for the 7 lots. The biofiltration basin will treat stormwater runoff from the site and outlet it into the public storm system on Brady Circle. The pervious pavement will treat any surface runoff and provide a little volume for water storage beneath the surface. A perforated pipe will be place below the pervious pavement to collect storm water and discharge it into Brady Circle via sidewalk underdrains. III. ROUTINE MAINTENANCE ACTIVITIES Primary maintenance activities include vegetation management, trash and sediment removal, irrigation maintenance and storm drain outlet inspections. The basins and swales are designed to fully drain within 24-72 hours and not include permanent pools or standing water. Routine maintenance activities, and the frequency at which they will be conducted, are shown in Table 1 below. NOTE: Landscape Maintenance Plan should also be reviewed for consistency with vegetation maintenance and any applicable needs for specific plants, shrubs or trees. Page 2 Table 1 Routine Maintenance Activities for Basins & Swales No. Maintenance Task Frequency of Task 1 Conduct annual vegetation management during the summer, removing weeds and harvesting vegetation. Remove all grass cuttings and other green waste. Once a year 2 Trim vegetation at beginning and end of wet season to prevent establishment of woody vegetation, and for aesthetics and mosquito control. Twice a year (spring and fall) 3 Evaluate health of vegetation and remove or replace any dead or dying plants. Remove all green waste and dispose of properly. Twice a year 4 If turf grass is included in basin/swale design, conduct regular mowing and remove all grass cuttings. Avoid producing ruts when mowing. As necessary to not allow grass over-growth 7 Remove accumulated trash and debris from the middle and end of the wet season and dispose of trash and debris properly. Twice a year (January and April) 8 Irrigate during dry weather. Per Landscape Plans 9 Inspect basins and swales using the attached inspection checklists. Quarterly, or as needed IV. PROHIBITIONS The use of pesticides and quick release fertilizers shall be minimized, and the principles of integrated pest management (IPM) followed: 1. Employ non-chemical controls (biological, physical and cultural controls) before using chemicals to treat a pest problem. 2. Prune plants properly and at the appropriate time of year. 3. Provide adequate irrigation for landscape plants. Do not over water. 4. Limit fertilizer use unless soil testing indicates a deficiency. Slow-release or organic fertilizer is preferable. Check with municipality for specific requirements. 5. Pest control should avoid harming non-target organisms, or negatively affecting air and water quality and public health. Apply chemical controls only when monitoring indicates that preventative and non-chemical methods are not keeping pests below acceptable levels. When pesticides are required, apply the least toxic and the least persistent pesticide that will provide adequate pest control. Do not apply pesticides on a prescheduled basis. 6. Sweep up spilled fertilizer and pesticides. Do not wash away or bury such spills. 7. Do not over apply pesticide. Spray only where the infestation exists. Follow the manufacturer’s instructions for mixing and applying materials. 8. Only licensed, trained pesticide applicators shall apply pesticides. Page 3 9. Apply pesticides at the appropriate time to maximize their effectiveness and minimize the likelihood of discharging pesticides into runoff. With the exception of pre-emergent pesticides, avoid application if rain is expected. 10. Unwanted/unused pesticides shall be disposed as hazardous waste. V. INSPECTIONS The attached Inspection and Maintenance Checklists shall be used to conduct inspections monthly (or as needed), identify needed maintenance, and record maintenance that is conducted. Page 4 Basin Inspection and Maintenance Checklist Property Address: Property Owner: Treatment Measure No.: Date of Inspection: Type of Inspection: Monthly ̀ Pre-Wet Season After heavy runoff ̀End of Wet Season Inspector(s): Other: ̀ Defect Conditions When Maintenance Is Needed Maintenance Needed? (Y/N)Comments (Describe maintenance completed and if any needed maintenance was not conducted, note when it will be done.) Results Expected When Maintenance Is Performed General Trash & Debris  Trash and debris accumulated in basin.  Visual evidence of dumping. Trash and debris cleared from site and disposed of properly. Poisonous Vegetation and noxious weeds Poisonous or nuisance vegetation or noxious weeds, e.g., morning glory, English ivy, reed canary grass, Japanese knotweed, purple loosestrife, blackberry, Scotch broom, poison oak, stinging nettles, or devil’s club. Use Integrated Pest Management techniques to control noxious weeds or invasive species. Contaminants and Pollution Any evidence of oil, gasoline, contaminants or other pollutants. No contaminants or pollutants present. Rodent Holes If facility acts as a dam or berm, any evidence of rodent holes, or any evidence of water piping through dam, berm or into slopes via rodent holes. The design specifications are not compromised by holes. Any rodent control activities are in accordance with applicable laws and do not affect any protected species. Insects Insects such as wasps and hornets interfere with maintenance activities. Insects do not interfere with maintenance activities. Basin & Swales Inspection and Maintenance Checklist Date of Inspection: Property Address: Treatment Measure No.: Page 5 Defect Conditions When Maintenance Is Needed Maintenance Needed? (Y/N)Comments (Describe maintenance completed and if any needed maintenance was not conducted, note when it will be done.) Results Expected When Maintenance Is Performed Tree/Brush Growth and Hazard Trees  Growth does not allow maintenance access or interferes with maintenance activity.  Dead, diseased, or dying trees/shrubs.  Trees do not hinder maintenance activities.  Remove hazard trees as approved by the City. (Use a certified Arborist to determine health of tree or removal requirements). Drainage time Standing water remains in basin more than five days. Correct any circumstances that restrict the flow of water from the system. Restore drainage to design condition. If the problem cannot be corrected and problems with standing water recur, then mosquitoes should be controlled with larvicides, applied by a licensed pesticide applicator. Outfall structure Debris or silt build-up obstructs an outfall structure. Remove debris and/or silt build-up and dispose of properly. Side Slopes Erosion  Eroded over 2 in. deep where cause of damage is still present or where there is potential for continued erosion.  Any erosion on a compacted berm embankment. Cause of erosion is managed appropriately. Side slopes or berm are restored to design specifications, as needed. Storage Area Sediment Accumulated sediment >10% of designed basin depth or affects inletting or outletting condition of the facility. Sediment cleaned out to designed basin shape and depth; basin reseeded if necessary to control erosion. Sediment disposed of properly. Liner (If Applicable) Liner is visible and has more than three 1/4-inch holes in it. Liner repaired or replaced. Liner is fully covered. Emergency Overflow / Spillway and Berms Settlement Berm settlement 4 inches lower than the design elevation. Dike is built back to the design elevation. Basin & Swales Inspection and Maintenance Checklist Date of Inspection: Property Address: Treatment Measure No.: Page 6 Defect Conditions When Maintenance Is Needed Maintenance Needed? (Y/N)Comments (Describe maintenance completed and if any needed maintenance was not conducted, note when it will be done.) Results Expected When Maintenance Is Performed Tree Growth Tree growth on berms or emergency spillway >4 ft in height or covering more than 10% of spillway.  Trees should be removed. If root system is small (base less than 4 inches) the root system may be left in place. Otherwise the roots should be removed and the berm restored.  A civil engineer should be consulted for proper berm/spillway restoration. Emergency Overflow/ Spillway Rock is missing and soil is exposed at top of spillway or outside slope. Rocks and pad depth are restored to design standards. Debris Barriers (e.g., Trash Racks) Trash and Debris Trash or debris is plugging openings in the barrier. Trash or debris is removed and disposed of properly. Damaged/ Missing Bars Bars are missing, loose, bent out of shape, or deteriorating due to excessive rust. Bars are repaired or replaced to allow proper functioning of trash rack. Inlet/Outlet Pipe Debris barrier is missing or not attached to pipe. Debris barrier is repaired or replaced to allow proper functioning of trash rack. Fencing and Gates Missing or broken parts Any defect in or damage to the fence or gate that permits easy entry to a facility. Fencing and gate are restored to design specifications. Deteriorating Paint or Protective Coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Paint or protective coating is sufficient to protect structural adequacy of fence or gate. Flow Duration Control Outlet (if included in design to meet Hydromodification Management Standard) Risers, orifices and screens Any debris or clogging Restore unobstructed flow through discharge structure; to meet original design; dispose of debris properly. Drawdown time Noticeable ponding exceeding 72-hours after a design storm event Restore infiltration and ponded waters permeate. Scarification should only be performed when there are signs of clogging rather than on a routine basis. Always remove deposited sediments before scarification and use a hand-guided rotary tiller. Swales (in addition to general items listed above) Basin & Swales Inspection and Maintenance Checklist Date of Inspection: Property Address: Treatment Measure No.: Page 7 Defect Conditions When Maintenance Is Needed Maintenance Needed? (Y/N)Comments (Describe maintenance completed and if any needed maintenance was not conducted, note when it will be done.) Results Expected When Maintenance Is Performed Impeded Flow Twice annually at beginning and end of wet season. After heavy runoff. Visible blockage or impediments. Trash and debris cleared from swale and disposed of properly especially prior to mowing. Landscaping or Vegetative Overgrowth Twice annually at beginning and end of wet season or as needed for aesthetics. Maintained flow and healthy vegetation. Miscellaneous Miscellaneous Any condition not covered above that needs attention to restore infiltration basin to design conditions. Meets the design specifications. BF-1 Biofiltration BMP MAINTENANCE FACT SHEET FOR STRUCTURAL BMP BF-1 BIOFILTRATION Biofiltration facilities are vegetated surface water systems that filter water through vegetation, and soil or engineered media prior to discharge via underdrain or overflow to the downstream conveyance system. Biofiltration facilities have limited or no infiltration. They are typically designed to provide enough hydraulic head to move flows through the underdrain connection to the storm drain system. Typical biofiltration components include: • Inflow distribution mechanisms (e.g., perimeter flow spreader or filter strips) • Energy dissipation mechanism for concentrated inflows (e.g., splash blocks or riprap) • Shallow surface ponding for captured flows • Side slope and basin bottom vegetation selected based on climate and ponding depth • Non-floating mulch layer • Media layer (planting mix or engineered media) capable of supporting vegetation growth • Filter course layer consisting of aggregate to prevent the migration of fines into uncompacted native soils or the aggregate storage layer • Aggregate storage layer with underdrain(s) • Impermeable liner or uncompacted native soils at the bottom of the facility • Overflow structure Normal Expected Maintenance Biofiltration requires routine maintenance to: remove accumulated materials such as sediment, trash or debris; maintain vegetation health; maintain infiltration capacity of the media layer; replenish mulch; and maintain integrity of side slopes, inlets, energy dissipators, and outlets. A summary table of standard inspection and maintenance indicators is provided within this Fact Sheet. Non-Standard Maintenance or BMP Failure If any of the following scenarios are observed, the BMP is not performing as intended to protect downstream waterways from pollution and/or erosion. Corrective maintenance, increased inspection and maintenance, BMP replacement, or a different BMP type will be required. • The BMP is not drained between storm events. Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health, and surface ponding longer than approximately 96 hours following a storm event poses a risk of vector (mosquito) breeding. Poor drainage can result from clogging of the media layer, filter course, aggregate storage layer, underdrain, or outlet structure. The specific cause of the drainage issue must be determined and corrected. • Sediment, trash, or debris accumulation greater than 25% of the surface ponding volume within one month. This means the load from the tributary drainage area is too high, reducing BMP function or clogging the BMP. This would require pretreatment measures within the tributary area draining to the BMP to intercept the materials. Pretreatment components, especially for sediment, will extend the life of components that are more expensive to replace such as media, filter course, and aggregate layers. • Erosion due to concentrated storm water runoff flow that is not readily corrected by adding erosion control blankets, adding stone at flow entry points, or minor re-grading to restore proper drainage according to the original plan. If the issue is not corrected by restoring the BMP to the original plan and grade, the [City Engineer] shall be contacted prior to any additional repairs or reconstruction. BF-1 Page 1 of 11 January 12, 2017 BF-1 Biofiltration Other Special Considerations Biofiltration is a vegetated structural BMP. Vegetated structural BMPs that are constructed in the vicinity of, or connected to, an existing jurisdictional water or wetland could inadvertently result in creation of expanded waters or wetlands. As such, vegetated structural BMPs have the potential to come under the jurisdiction of the United States Army Corps of Engineers, SDRWQCB, California Department of Fish and Wildlife, or the United States Fish and Wildlife Service. This could result in the need for specific resource agency permits and costly mitigation to perform maintenance of the structural BMP. Along with proper placement of a structural BMP, routine maintenance is key to preventing this scenario. BF-1 Page 2 of 11 January 12, 2017 BF-1 Biofiltration SUMMARY OF STANDARD INSPECTION AND MAINTENANCE FOR BF-1 BIOFILTRATION The property owner is responsible to ensure inspection, operation and maintenance of permanent BMPs on their property unless responsibility has been formally transferred to an agency, community facilities district, homeowners association, property owners association, or other special district. Maintenance frequencies listed in this table are average/typical frequencies. Actual maintenance needs are site-specific, and maintenance may be required more frequently. Maintenance must be performed whenever needed, based on maintenance indicators presented in this table. The BMP owner is responsible for conducting regular inspections to see when maintenance is needed based on the maintenance indicators. During the first year of operation of a structural BMP, inspection is recommended at least once prior to August 31 and then monthly from September through May. Inspection during a storm event is also recommended. After the initial period of frequent inspections, the minimum inspection and maintenance frequency can be determined based on the results of the first year inspections. Threshold/Indicator Maintenance Action Typical Maintenance Frequency Accumulation of sediment, litter, or debris Remove and properly dispose of accumulated materials, without damage to the vegetation or compaction of the media layer. • Inspect monthly. If the BMP is 25% full* or more in one month, increase inspection frequency to monthly plus after every 0.1-inch or larger storm event. • Remove any accumulated materials found at each inspection. Obstructed inlet or outlet structure Clear blockage. • Inspect monthly and after every 0.5-inch or larger storm event. • Remove any accumulated materials found at each inspection. Damage to structural components such as weirs, inlet or outlet structures Repair or replace as applicable • Inspect annually. • Maintenance when needed. Poor vegetation establishment Re-seed, re-plant, or re-establish vegetation per original plans. • Inspect monthly. • Maintenance when needed. Dead or diseased vegetation Remove dead or diseased vegetation, re-seed, re-plant, or re-establish vegetation per original plans. • Inspect monthly. • Maintenance when needed. Overgrown vegetation Mow or trim as appropriate. • Inspect monthly. • Maintenance when needed. 2/3 of mulch has decomposed, or mulch has been removed Remove decomposed fraction and top off with fresh mulch to a total depth of 3 inches. • Inspect monthly. • Replenish mulch annually, or more frequently when needed based on inspection. *“25% full” is defined as ¼ of the depth from the design bottom elevation to the crest of the outflow structure (e.g., if the height to the outflow opening is 12 inches from the bottom elevation, then the materials must be removed when there is 3 inches of accumulation – this should be marked on the outflow structure). BF-1 Page 3 of 11 January 12, 2017 BF-1 Biofiltration SUMMARY OF STANDARD INSPECTION AND MAINTENANCE FOR BF-1 BIOFILTRATION (Continued from previous page) Threshold/Indicator Maintenance Action Typical Maintenance Frequency Erosion due to concentrated irrigation flow Repair/re-seed/re-plant eroded areas and adjust the irrigation system. • Inspect monthly. • Maintenance when needed. Erosion due to concentrated storm water runoff flow Repair/re-seed/re-plant eroded areas, and make appropriate corrective measures such as adding erosion control blankets, adding stone at flow entry points, or minor re-grading to restore proper drainage according to the original plan. If the issue is not corrected by restoring the BMP to the original plan and grade, the [City Engineer] shall be contacted prior to any additional repairs or reconstruction. • Inspect after every 0.5-inch or larger storm event. If erosion due to storm water flow has been observed, increase inspection frequency to after every 0.1-inch or larger storm event. • Maintenance when needed. If the issue is not corrected by restoring the BMP to the original plan and grade, the [City Engineer] shall be contacted prior to any additional repairs or reconstruction. Standing water in BMP for longer than 24 hours following a storm event Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health Make appropriate corrective measures such as adjusting irrigation system, removing obstructions of debris or invasive vegetation, clearing underdrains, or repairing/replacing clogged or compacted soils. • Inspect monthly and after every 0.5-inch or larger storm event. If standing water is observed, increase inspection frequency to after every 0.1-inch or larger storm event. • Maintenance when needed. Presence of mosquitos/larvae For images of egg rafts, larva, pupa, and adult mosquitos, see http://www.mosquito.org/biology If mosquitos/larvae are observed: first, immediately remove any standing water by dispersing to nearby landscaping; second, make corrective measures as applicable to restore BMP drainage to prevent standing water. If mosquitos persist following corrective measures to remove standing water, or if the BMP design does not meet the 96-hour drawdown criteria due to release rates controlled by an orifice installed on the underdrain, the [City Engineer] shall be contacted to determine a solution. A different BMP type, or a Vector Management Plan prepared with concurrence from the County of San Diego Department of Environmental Health, may be required. • Inspect monthly and after every 0.5-inch or larger storm event. If mosquitos are observed, increase inspection frequency to after every 0.1-inch or larger storm event. • Maintenance when needed. Underdrain clogged Clear blockage. • Inspect if standing water is observed for longer than 24-96 hours following a storm event. • Maintenance when needed. BF-1 Page 4 of 11 January 12, 2017 BF-1 Biofiltration References American Mosquito Control Association. http://www.mosquito.org/ California Storm Water Quality Association (CASQA). 2003. Municipal BMP Handbook. https://www.casqa.org/resources/bmp-handbooks/municipal-bmp-handbook County of San Diego. 2014. Low Impact Development Handbook. http://www.sandiegocounty.gov/content/sdc/dpw/watersheds/susmp/lid.html San Diego County Copermittees. 2016. Model BMP Design Manual, Appendix E, Fact Sheet BF-1. http://www.projectcleanwater.org/index.php?option=com_content&view=article&id=250&Itemid=220 BF-1 Page 5 of 11 January 12, 2017 BF-1 Biofiltration Page Intentionally Blank for Double-Sided Printing BF-1 Page 6 of 11 January 12, 2017 BF-1 Biofiltration Date: Inspector: BMP ID No.: Permit No.: APN(s): Property / Development Name: Responsible Party Name and Phone Number: Property Address of BMP: Responsible Party Address: INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 1 of 5 Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted Accumulation of sediment, litter, or debris Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Remove and properly dispose of accumulated materials, without damage to the vegetation ☐ If sediment, litter, or debris accumulation exceeds 25% of the surface ponding volume within one month (25% full*), add a forebay or other pre-treatment measures within the tributary area draining to the BMP to intercept the materials. ☐ Other / Comments: Poor vegetation establishment Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Re-seed, re-plant, or re-establish vegetation per original plans ☐ Other / Comments: *“25% full” is defined as ¼ of the depth from the design bottom elevation to the crest of the outflow structure (e.g., if the height to the outflow opening is 12 inches from the bottom elevation, then the materials must be removed when there is 3 inches of accumulation – this should be marked on the outflow structure). BF-1 Page 7 of 11 January 12, 2017 I I I BF-1 Biofiltration Date: Inspector: BMP ID No.: Permit No.: APN(s): INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 2 of 5 Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted Dead or diseased vegetation Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Remove dead or diseased vegetation, re- seed, re-plant, or re-establish vegetation per original plans ☐ Other / Comments: Overgrown vegetation Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Mow or trim as appropriate ☐ Other / Comments: 2/3 of mulch has decomposed, or mulch has been removed Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Remove decomposed fraction and top off with fresh mulch to a total depth of 3 inches ☐ Other / Comments: BF-1 Page 8 of 11 January 12, 2017 BF-1 Biofiltration Date: Inspector: BMP ID No.: Permit No.: APN(s): INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 3 of 5 Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted Erosion due to concentrated irrigation flow Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Repair/re-seed/re-plant eroded areas and adjust the irrigation system ☐ Other / Comments: Erosion due to concentrated storm water runoff flow Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Repair/re-seed/re-plant eroded areas, and make appropriate corrective measures such as adding erosion control blankets, adding stone at flow entry points, or minor re-grading to restore proper drainage according to the original plan ☐ If the issue is not corrected by restoring the BMP to the original plan and grade, the [City Engineer] shall be contacted prior to any additional repairs or reconstruction ☐ Other / Comments: BF-1 Page 9 of 11 January 12, 2017 BF-1 Biofiltration Date: Inspector: BMP ID No.: Permit No.: APN(s): INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 4 of 5 Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted Obstructed inlet or outlet structure Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Clear blockage ☐ Other / Comments: Underdrain clogged (inspect underdrain if standing water is observed for longer than 24-96 hours following a storm event) Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Clear blockage ☐ Other / Comments: Damage to structural components such as weirs, inlet or outlet structures Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Repair or replace as applicable ☐ Other / Comments: BF-1 Page 10 of 11 January 12, 2017 BF-1 Biofiltration Date: Inspector: BMP ID No.: Permit No.: APN(s): INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 5 of 5 Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted Standing water in BMP for longer than 24-96 hours following a storm event* Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Make appropriate corrective measures such as adjusting irrigation system, removing obstructions of debris or invasive vegetation, clearing underdrains, or repairing/replacing clogged or compacted soils ☐ Other / Comments: Presence of mosquitos/larvae For images of egg rafts, larva, pupa, and adult mosquitos, see http://www.mosquito.org/biology Maintenance Needed? ☐ YES ☐ NO ☐ N/A ☐ Apply corrective measures to remove standing water in BMP when standing water occurs for longer than 24-96 hours following a storm event.** ☐ Other / Comments: *Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health, and surface ponding longer than approximately 96 hours following a storm event poses a risk of vector (mosquito) breeding. Poor drainage can result from clogging of the media layer, filter course, aggregate storage layer, underdrain, or outlet structure. The specific cause of the drainage issue must be determined and corrected. **If mosquitos persist following corrective measures to remove standing water, or if the BMP design does not meet the 96-hour drawdown criteria due to release rates controlled by an orifice installed on the underdrain, the [City Engineer] shall be contacted to determine a solution. A different BMP type, or a Vector Management Plan prepared with concurrence from the County of San Diego Department of Environmental Health, may be required. BF-1 Page 11 of 11 January 12, 2017 Attachment 4 City Standard Single Sheet BMP (SSBMP) Exhibit Page intentionally blank 110 COPPERWOOD WAY, SUITE P, OCEANSIDE, CA 92058 PH: 760-908-8745 ● info@civillandworks.com 20 0 20 GRAPHIC SCALE SCALE: 1"= 20' 40 I I 6' MIN. FREEBOARD 6" MIN. FREEBOARD - i----------5.0D'--------- 24'X24" OVERFLOW ~ RISER I 148·~0FG 12" WATER SURFACE -----..._ "'-.._ -3~--.....,__ 'v 148.30TG ~~1 "' IMPERMEABLE LINER* ijll 147.30FG MIRAFI 140N OR EQUIV.~ ,l~f 1//#~////~1//(/1/ ~ /j 1:1 EXCAVATED u-I El · SLOPE ·~111~11111 11~~111~111~1 I IL,llf11J.t 1-~111"-I _!_I 7=- MIN. 18" MEDIA **WITH 6, PERFORATED FIL :~TliN 1~; PIPE • / , EXISTING 3 OF 3 8 GRAVEL UNCOMPACTED SOILS UNDER PERFORATED PIPE ~ ORIFICE PLATE (4.6" ORIFICE) 148.BOFG RIPRAP PER PLAN 148.75FG ~ TERRA TEXN0.3 FILTER BLANKET T; 2 BLANKETS IMPERMEABLE LINER* MIRAFI 140N OR EQUIV. 10' TOTAL OF 3/8" GRAVEL PERVIOUS MICROFIL TER F AIBRIC AROUND GRAVEL MIRAFI 140N "FILTRATION" OR EQUIVALENT 12" SD OUTLET 144.971E SEE DETAIL RIGHT *IMPERMEABLE LINER TO BE PLACED ALONG THE SIDES OF THE BIORETENTION BASIN **BIORffiNTION 'ENGINEERED SOIL"LAYER SHALL BE MINIMUM 18"DEEP 'SANDY LOAM"SOIL MIX 1'11TH NO MORE THAN 5% CLAY CONTENT. THE MIX SHALL CONTAIN 50-60% SAND, 20-30% COMPOST OR HARDWOOD MULCH, AND 20-30% TOPSOIL INFLOW PIPE 7 ~ VOID FILLER - 1 /8" TO 3/8" (NO. 8) 3 1 /8' MIN. THICKNESS ~ AGGREGATE IN VOIDS PAYERS W/ MIN. 3/8" VOID . ""' BEDDING COURSE -1.5' ----... _ -" THICK OF 1/8' TO 3/8" ...., ~-. -mr---:_• -CONCRETE FOOTING MIN. 12" IN SUBGRADE {N0.8) AGGREGATE , • •• --• 0.5' ~ ~ .. , • . 3' PERFORATED PIPE 6' CLASS 2 AGGREGATE Ii" • SCH 40, PVC .• I a l~I I ~ PIPE AT 1" __/ 1• \_ AIBOVE SUBGRADE 4•5 SOIL SUBGRADE PERMEABLE PAVERS DETAIL OR EQUIVALENT ORIFICE PLATE: MIN SQUARE DIMENSIONS 1.0 FT. GREATER ~ THAN PIPE DIA. HOT-DIP GALVANIZED PLATE AFTER HOLES HAVE BEEN DRILLED NQlE:. N.T.S. BMP ID# BMPTYPE SYMBOL TREATMENT CONTROL 0 BIOFILTRATION + • • • AREA ••••• + ••• 0 PERVIOUS PAVEMENT Q) BMPSIGN -0- PARTY RESPONSIBLE FOR MAINTENANCE: NAME_~MA=GN=O=LIA=A=3=LL~C __ ADDRESS 5 HOYA STREET CONTACT BEN RYAN RANCHO MISSION VIEJO CA -----"~"-=-- PHONE NO. /8581794-1900 PLAN PREPARED BY: NAME_~D=AV=ID~C~AR=O~N __ _ COMPANY CIVIL L,ANDWORKS CORP ADDRESS 110 COPPERWOOD WAY SUITE P OCEANSIDE CA 92058 PHONE NO. (760) 908-8745 SIGNATURE BMPNOTES: 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. CONSTRUCTION NOTES: (D CONSTRUCT BIOFILTRATION BASIN PER DETAIL 1 SHEET 3 OF DWG. 515-3A @ INSTALL PERMEABLE PAYERS PER DETAIL SHEET 6 OF DWG. 515-3A Q) INSTALL BMP SIGN & DETAIL PER THIS SHEET PERMANENT WATER QUALITY TREATMENT FACILITY KEEPING OUR WATER WAYS CLEAN MAINTAIN 1'11TH CARE -NO MODIFICATIONS WITHOUT AGENCY APPROVAL DETAIL WATER QUALITY SIGN -PLACED AT EACH BIOFIL TRATION BASIN CASQA NO. TC-32 TC-10 NOTE: ALL BIOFIL TRA TION AREAS WILL HAVE A SIGN POSTED TO BE VISIBLE AT ALL TIMES. BMP TABLE QUANTITY DRAWING NO. SHEET NO.(S) ..!..1§Q_ SF. 515-3A 2 6,507 SF. 515-3A 4,5 1 EA. 515-3A 3 INSPECTION * MAINTENANCE * FREQUENCY FREQUENCY QUARTERLY SEMI-ANNUALLY SEMI-ANNUALLY ANNUALLY SEMI-ANNUALLY ANNUALLY 1. ORIFICE PLATE & FLANGE CONNECTION TO CONCRETE SHALL BE FlffiD WITH 30 DUROMETER NEOPRENE RING. f"sHml CITY OF CARLSBAD I SHE3ETS I t-----+----+--------------+----+-----t---+----t L...:_J ENGINEERING DEPARTMENT l-----+----+--------------+----+------l---+-----1 1-----+----+--------------+----+------1---+-----1 GRADING PLANS FOR: 2. MAINTENANCE ACCESS FROM 24"X24' RISER. 3. CLEARING OF ORIFICE TO BE CLEANED 'MTH WATER JET OR EQUIVALENT METHODS \._ORIFICE 4.6" DIAMETER (DIA) MAGNOLIA -BRADY GR2018-0047 SINGLE SHEET BMP SITE PLAN APPROVED: JASON S. GELDERT Civil nandworks t-----+----+-11~\-------------+--+---+----+----t :::;C::::::ITY::::::::EN=Gl=NE=E==R ==~RC;:::E:::::6=3=91=2=EX=P=IR=ES=9=/=:3::::o:::;/:2';:o===D=ATE=::::: DETAIL 1: BIOFILTRATION WllH WAIL DWN BY: PN PROJECT NO. DRAWING NO. "' PARTIAL RETENTION BASIN FLOW CONJROL QRIF)CE PLAJE DATE INITIAL REVISION DESCRIPTION DATE INITIAL DATE INITIAL CHKD BY: --CT2018-0003 515-3A ~ ... ________ .... ________________________________________ ...;,N~TS;_ _____________________________ N_TS;_ _______________ .;;;EN;;Gl;;NEE;;R~OF;;WO~RK;:;;~~~~~~~~~~~~~;;:;O;;TH;;ER~AP;;PR;;OV;;A;;L;:;;C;;ITY~Af>;;P;;RO;;V;;AL;;;;;RVWD~~BY;;:~~~~~~~~~~~~~~~~ 11,\j)RA .... FUS\1111.E SHEE!S\ORADINO 1111.E SHEET.DWO RE\OSED,02/10/17