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Home My WebLink AboutPD 2021-0040; 786 PALM AVENUE; TRASH CAPTURE STORM WATER QUALITY MANAGEMENT PLAN (SWQMP); 2022-08-10 TRASH CAPTURE SWQMP OUTLINE [The following outline describes what is expected in the Trash Capture SWQMP. Do not include the following outline as a part of the Trash Capture SWQMP.] Section Content Description Title Page Table of Contents Certification Page This template contains suggested content for a certification page. This may be replaced by jurisdiction specific certification page Project Vicinity Map Placeholder for applicant to insert a vicinity map, required for all projects City Storm Water Standards Questionnaire Form E-34 i.e., is this project a development project subject to storm water requirements? which requirements apply? Site Information Checklist Base information about the project site that usually remains the same even as structural BMP designs evolve. 3B is not the place to put BMP information – BMP information goes in Forms 4, 5 and 6, and Attachments. City Standard Project Requirement Checklist Form E-36 Project applicant must acknowledge/answer each required source control BMP. Project applicant must acknowledge/answer each required site design BMP Summary of Trash Capture BMPs Project applicant to identify each structural BMP to be implemented, identify party responsible for certification following construction, future owner, and party responsible for on-going maintenance into perpetuity. BMP design information will be included in Attachments 1 and 2. Attachment 1: Backup for Trash Capture BMPs There are several required elements in this backup for pollutant control. The Attachment cover page lists the required elements as a checklist for what the applicant should include in the Attachment. Attachment 1a: DMA Exhibit A checklist of the minimum elements of the DMA Exhibit is provided at the back of the attachment 1 cover sheet. Attachment 1b: Tabular Summary of DMAs Attachment 1c: Trash Capture BMP Design Worksheets/Calculations Project applicant to insert all applicable trash capture BMP sizing calculations including sizing worksheets, hand calculations, custom spreadsheets created by the applicant, etc. Attachment 2: Trash Capture BMP Maintenance Thresholds and Actions Checklists for the contents of this attachment are provided – requirements for this information will vary depending on project status. Attachment 3: City standard Trash Capture BMP Exhibit A checklist of required elements to show on the plans is provided. This is a comprehensive site plan (24” x 36” size) of the project showing the type and locations of Trash Capture, Site Design, LID and Source Control BMP’s. Use the City’s template trash capture BMP plan, latest version. E-35A REV 09/21 TRASH CAPTURE STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) TEMPLATE E-35A D e v e l o p m e n t Services Land Development Engineering 1635 Faraday Avenue 760‐602‐2750 www.carlsbadca.gov 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 Trash Capture Structural BMPs Attachment 1: Backup for Trash Capture BMPs Attachment 1a: DMA Exhibit Attachment 1b: Tabular Summary of DMAs Attachment 1c: Trash Capture BMP Design Calculations Attachment 2: Trash Capture BMP Maintenance Thresholds and Actions Attachment 3: Single Sheet BMP (SSBMP) Exhibit PROJECT VICINITY MAP SITE INFORMATION CHECKLIST Project Summary Information Project Name 786 Palm Avenue Project ID PD2021-0040 Project Address 786 Palm Avenue Carlsbad, Ca 92008 Assessor's Parcel Number(s) (APN(s)) 204-171-10, 204-171-11 Project Watershed (Hydrologic Unit) Carlsbad 904 Parcel Area 0.16 Acres 6,993 Square Feet Description of Existing Site Condition and Drainage Patterns Select applicable Land Use Category: High Density Residential ☑R-23 (15-23 du/ac) R-30 (23-30 du/ac) Industrial  PI (Planned Industrial) Commercial  CF (Community Facilities)  GC (General Commercial)  L (Local Shopping Center)  R (Regional Commercial)  V-B (Village-Barrio)  VC (Visitor Commercial)  O (Office)  VC/OS (Visitor Commercial/Open Space) Mixed Urban  PI/O (Planned Industrial/Office)  Public Transportation Stations 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]: Storm flows affecting the site are limited to the rainfall that lands directly on the properties. In the existing condition, urban runoff sheet flows in a southwesterly direction from the northwest corner of APN 204-171-10 to Point of Compliance (POC 1) at the southwest corner of APN 204- 171-11. Description of Proposed Site Development and Drainage Patterns Project Description / Proposed Land Use and/or Activities: The 786 Palm Avenue Project proposes the construction of two (2) separate single-family two- story residential buildings with associated improvements on two (2) assessor’s parcel numbers (APN) APN 204-171-10 and APN 204-171-11. Additionally, an accessory dwelling unit is proposed on the second story of each residential building. Does the project include grading and changes to site topography?  Yes   No Description / Additional Information: Proposed changes to the site topography include grading of drainage swales to direct runoff around the proposed two residential buildings. Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)?  Yes   No Description / Additional Information: Proposed new storm water conveyance systems include a Bio Clean Curb Guard at the southwest corner of APN 171-141-10 and a small infiltration basin at the northwest corner of APN 171-141- 11. 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. SUMMARY OF TRASH CAPTURE BMPS Trash Capture BMPs All projects subject to trash capture requirements must implement trash capture BMPs (see Chapter 4 of the BMP Design Manual). Selection of trash capture BMPs must be based on the selection process described in Chapter 4. Trash capture 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 trash capture BMPs (see Section 1.12 of the BMP Design Manual). Trash capture 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 trash capture BMP implementation at the project site in the box below. Then complete the trash capture BMP summary information sheet for each trash capture BMP within the project (copy the BMP summary information page as many times as needed to provide summary information for each trash capture BMP). Describe the general strategy for trash capture BMP implementation at the site. This information must describe how the steps for selecting and designing trash capture BMPs presented in Section 4.4 of the BMP Design Manual were followed, and the results (type of BMPs selected). The trash capture BMP selected for APN 204-141-10 is a Bio CleanCurb Guard placed inside a Type A Curb Outlet per D-25 of the SDRSD. The trash capture BMP selected for APN 204-141-11 is an infiltration basin at the northwest corner of the property. The infiltration basin was selected because the lot drains towards an existing alley, with no adjacent curb to discharge runoff via a Type A Curb Outlet per D-25. [Continued from previous page – This page is reserved for continuation of description of general strategy for trash capture BMP implementation at the site.] Trash Capture BMP Summary Information BMP ID No. Type of Trash Capture BMP Permit No. Drawing No. 1 Bio CleanCurb Guard placed inside a Type A Curb Outlet per D-25 of the SDRSD. GR2021-0040 DWG 534-4A 2 Infiltration Basin GR2021-0040 DWG 534-4A ATTACHMENT 1 BACKUP FOR TRASH CAPTURE 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 Trash Capture BMP Design Worksheets / Calculations (Required) Refer to Appendices J of the BMP Design Manual for trash capture BMP design guidelines Included ATTACHMENT 1A DMA Exhibit: The DMA Exhibit must identify:  Site topography and impervious areas  Site drainage network and connections to drainage offsite  Proposed grading (if applicable)  Drainage management area (DMA) boundaries, DMA ID numbers, and DMA areas (square footage or acreage)  Trash Capture BMPs (identify location and type of BMP) SMH 51.19 FLSMH 48.10 FL UP UP RONALD L. HOLLOWAY NO. 29271 241,'%6%*#4#%6'4+56+%5 LEGEND SYMBOL 3" MULCH INFILTRATION BASIN DETAIL, BMP 2 18" 3/4" CRUSHED GRAVEL 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR 4" PEA GRAVEL K:\Civil 3D\1501\DWG\SWMP\1501_DMA EXHIBIT.dwg, 8/24/2022 9:15:06 AM RONALD L. HOLLOWAY NO. 29271 K:\Civil 3D\1501\DWG\SWMP\1501_DMA EXHIBIT.dwg, 8/24/2022 9:18:49 AM ATTACHMENT 1B TABULAR SUMMARY OF DMAS Surface Name Surface Type Area (ft 2) R1 Roof and Concrete Sidewalk 571 571 Surface Name Surface Type Area (ft 2) L1 Permeable Surfaces and Landscape 803 803 1,374 42% B 0.43 0.58 29Design Capture Volume (DVC) = (C)(I)(A) ⁄ 12 Total Impervious Area (ft2) DMA Pervious Area Tabulation Total Impervious Area (ft2) ⁄ Total DMA (ft2) = Percent Impervious Soil Type DMA Runoff Factor “C” per Appendix B.1 and B.2 85th Percentile Rainfall (I) Total Pervious Area (ft2) Total DMA (A) DMA Surface Tabulation to Support Biofiltration of Design Capture Volume (DCV) Determination DMA Name – DMA 1 DMA Impervious Area Tabulation Surface Name Surface Type Area (ft 2) R1 Roof and Concrete Sidewalk 571 571 Surface Name Surface Type Area (ft 2) L1 Permeable Surfaces and Landscape 1,041 1,041 1,612 35% B 0.38 0.58 30 Total Impervious Area (ft2) ⁄ Total DMA (ft2) = Percent Impervious Soil Type DMA Runoff Factor “C” per Appendix B.1 and B.2 85th Percentile Rainfall (I) Design Capture Volume (DVC) = (C)(I)(A) ⁄ 12 Total Pervious Area (ft2) Total DMA (A) Total Impervious Area (ft2) DMA Pervious Area Tabulation DMA Surface Tabulation to Support Biofiltration of Design Capture Volume (DCV) Determination DMA Name – DMA 1 DMA Impervious Area Tabulation ATTACHMENT 1C TRASH CAPTURE BMP DESIGN WORKSHEETS/CALCULATIONS BMP 1 Up Node Total Area (ac) C1 A1 (AC) C2 A2 (AC) CCOMP DMA 1 0.032 0.25 0.013 0.90 0.018 0.63 COEFFICIENT RUNOFF Q=CIA C I (in/hr) A (ac)Q (cfs) 0.63 0.47 0.032 0.009 HYDROLOGY AND HYDRAULICS (1 YEAR - 1 HOUR STORM EVENT) Use a flat mounted Bio Clean Curb Guard with Connector Pipe Screen attached to opening of D-25 Curb Outlet per SDRSD. See grading plan DWG 534-4A for details. ATTACHMENT 2 BMP 2 1 Remaining DCV after implementing retention BMPs 30 cubic-feet 2 Infiltration rate from Worksheet D.5-1 if partial infltration is feasible 0.2 in/hr. 3 Allowable drawdown time for aggregate storage below the underdrain 36 hours 4 Depth of runoff that can be infiltrated [Line 2 x Line 3] 7.2 inches 5 Aggregate pore space 0.4 in/in 6 Required depth of gravel below the underdrain [Line 4 / Line 5] 18 inches 7 Assumed surface area of the biofiltration BMP 25 sq-ft 8 Media retained pore space 0.1 in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 19 cubic-feet 10 DCV that requires biofiltration [Line 1 - Line 9] 11 cubic-feet 11 Surface Ponding [6 inch minimum, 12 in maximum] 3 inches 12 Media Thickness [18 inches minimum] 18 inches 14 Media available pore space 0.2 in/in 15 Media filtration rate to be used for sizing 5 in/hr. 16 Allowable Routing Time for sizing 6 hours 17 Depth filtered during storm [Line 15 x Line 16] 30 inches Depth of Detention Storage [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 19 Total Depth Treated [Line 17 + Line 18] 43.8 inches 20 Required biofiltered volume [1.5 x Line 10] 11 cubic-feet 21 Required Footprint [Line 20 / Line19] x 12 3 sq-ft 28 Used BMP Footprint 25 sq-ft Biofilter the DCV Baseline Calculation 18 13.8 inches 13 Aggregate Storage above underdrain invert (12 inches typical - use 0 inches for sizing if aggregate is not over the entire bottom surface area 18 inches BMP Parameters Simple Sizing Method for Biofiltration BMPs- BMP 1 Worksheet B.5-1 Partial Retention Up Node Total Area (ac) C1 A1 (AC) C2 A2 (AC) CCOMP DMA 1 0.097 0.25 0.024 0.90 0.013 0.34 COEFFICIENT RUNOFF Q=CIA C I (in/hr) A (ac)Q (cfs) 0.34 0.47 0.097 0.015 HYDROLOGY AND HYDRAULICS Use a 2 inch deep by 5 foot by 5 foot Infiltration Basin for Trash Capture. See grading plan DWG 534-4A for details. Flows greater than the trash capture peak flow of 0.015 cfs will overflow onto the alley. ATTACHMENT 3 Trash Capture BMP Maintenance Information Typical Maintenance Indicator(s) for Vegetated BMPs Maintenance Actions Accumulation of sediment, litter, or debris Remove and properly dispose of accumulated materials, without damage to the vegetation. Poor vegetation establishment Re‐seed, re‐plant, or re‐establish vegetation per original plans. Overgrown vegetation Mow or trim as appropriate, but not less than the design height of the vegetation per original plans when Erosion due to concentrated irrigation flow Repair/re‐seed/re‐plant eroded areas and adjust the irrigation system. Erosion due to concentrated storm water runoff flow Repair/re‐seed/re‐plant eroded areas, and make appropriate corrective measures such as adding erosion Standing water in vegetated swales used for pretreatment and/or site design BMPs Make appropriate corrective measures such as adjusting irrigation system, removing obstructions of debris or Standing water in bioretention, biofiltration with partial retention, or biofiltration areas, or flow‐through planter Make appropriate corrective measures such as inspecting/unclogging orifice opening, adjusting irrigation Damage to structural components such as weirs, inlet or outlet structures Repair or replace as applicable. MAINTENANCE INDICATORS AND ACTIONS FOR INFILTRATION BASINS Accumulation of sediment, litter, or debris Remove and properly dispose accumulated materials. Obstructed inlet or outlet structure Clear obstructions. Clogged filter media Remove and properly dispose filter media, and replace with fresh media. Damage to components of the filtration system Repair or replace as applicable. MAINTENANCE INDICATORS AND ACTIONS FOR TRASH CAPTURE BMPS ATTACHMENT 4 City Standard Trash Capture BMP Exhibit SMH 51.19 FLSMH 48.10 FL UP UP RONALD L. HOLLOWAY NO. 29271 241,'%6%*#4#%6'4+56+%5 LEGEND SYMBOL 3" MULCH INFILTRATION BASIN DETAIL, BMP 2 18" 3/4" CRUSHED GRAVEL 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR 4" PEA GRAVEL K:\Civil 3D\1501\DWG\SWMP\1501_TRASH CAPTURE EXHIBIT.dwg, 8/24/2022 9:20:03 AM RONALD L. HOLLOWAY NO. 29271 K:\Civil 3D\1501\DWG\SWMP\1501_TRASH CAPTURE EXHIBIT.dwg, 8/24/2022 9:21:08 AM