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Home My WebLink AboutHMP 15-01; MARTIN RESIDENCE; PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER QUALITY MANAGEMENT PLAN (SWQMP); 2016-12-13------.. ---- --- ---- -------------- - TABLE OF CONTENTS Certification Page Project Vicinity Map . FORM E-34 Storm Water Standard Questionnaire Site Information FORM E-36 Standard Project Requirement Checklist Summary of PDP Structural BMPs Attachment 1: Backup for PDP Pollutant Control BMPs Attachment 1 a: OMA Exhibit Attachment 1 b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable) Attachment 1 e: Pollutant Control BMP Design Worksheets / Calculations Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit Attachment 2b: Management of Critical Coarse Sediment Yield Areas Attachment 2c: Geomorphic Assessment of Receiving Channels Attachment 2d: Flow Control Facility Design Attachment 3: Structural BMP Maintenance Thresholds and Actions Attachment 4: Single Sheet BMP (SSBMP) Exhibit -------------------------------------------------- ---«' ~ CITY OF CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov ----------------------------------------------------.. - 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 (BMP's) into the project design per the City's Standard Urban Stormwater Management Plan (SUSMP). To view the SUSMP, refer to the Engineering Standards (Volume 4, Chapter 2) at www.carlsbadca.gov/standards. Initially 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 Stormwater Requirements' or be subject to additional criteria called 'Priority Development Project Requirements'. Many aspects of project site design are dependent upon the storm water standards applied to a project. 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. - -.. - --- w --- - A separate completed and signed questionnaire must be submitted for each new development application submission. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. In addition to this questionnaire, you must also complete, sign and submit a Project Threat Assessment Form with construction permits for the project. Please start by completing Step 1 and follow the instructions. When completed, sign the form at the end and submit this with your application to the city . STEP1 TO BE COMPLETED FOR ALL PROJECTS To determine if your project is a priority development project, please answer the following questions: YES NO 1. Is your project LIMITED TO constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria: (1) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-erodible permeable areas; OR (2) designed and constructed to be hydraulically disconnected from X paved streets or roads; OR (3) designed and constructed with permeable pavements or surfaces in accordance with USEPA Green Streets auidance? 2. Is your project LIMITED TO retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in accordance with the USEPA Green Streets guidance? X If you answered "yes" to one or more of the above questions, then your project is NOT a priority development project and therefore is NOT subject to the storm water criteria required for priority development projects. Go to step 4, mark the last box stating "my project does not meet PDP requirements" and complete applicant information. If you answered "no" to both auestions, then go to Step 2. E-34 Page 1 of 3 Effective 6/27/13 -- --... ----.... ----- ----.. -- -.. -- - ---- «~' ~ CITY OF CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov STEP2 TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS To determine if your project is a priority development project, please answer the following questions: YES 1. Is your project a new development that creates 10,000 square feet or more of impervious surfaces collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, and public develooment oroiects on oublic or orivate land. 2. Is your project creating or replacing 5,000 square feet or more of impervious surface collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surface? This includes commercial, industrial, residential, mixed-use, and oublic develooment oroiects on oublic or orivate land. 3 . Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumotion. 4. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a hillside development project? A hillside development X project includes development on any natural slope that is twenty-five percent or greater. 5. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a parking lot. A parking lot is a land area or facility for the temoorarv oarkina or storaae of motor vehicles used oersonally for business or for commerce. 6. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a street, road, highway freeway or driveway? A street, road, highway, freeway or driveway is any paved impervious surface used for the transportation of X automobiles, trucks, motorcycles, and other vehicles. 7. Is your project a new or redevelopment project that creates or replaces 2,500 square feet or more of impervious surface collectively over the entire site, and discharges directly to an Environmentally Sensitive Area {ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of 200 feet or less X from the project to the ESA, or conveyed in a pipe or open channel any distance as an isolated flow from the oroiect to the ESA (i.e. not comminales with flows from adjacent lands).* 8. Is your project a new development that supports an automotive repair shop? An automotive repair shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC) codes: 5013, 5014, 5541, 7532-7534, or 7536-7539. 9. Is your project a new development that supports a retail gasoline outlet {RGO)? This category includes RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily Traffic (ADT) of 100 or more vehicles per day. 10. ls your project a new or redevelopment project that results in the disturbance of one or more acres of land and are expected to generate pollutants post construction? 11. ls your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of impervious surface or (2) increases impervious surface on the property by more than 10%? NO X X X X X X X V If you answered "yes" to one or more of the above questions, you ARE a priority development project and are therefore subject to implementing structural Best Management Practices {BMP's) in addition to implementing Standard Storm Water Requirements such as source control and low impact development BMP's. A Storm Water Management Plan {SWMP) must be submitted with your application{s) for development. Go to step 3 for redevelopment projects. For new projects, go to step 4 at the end of this questionnaire, check the "my project meets PDP requirements" box and complete applicant information. If you answered "no" to all of the above questions, you ARE NOT a priority development project and are therefore subject to implementing only Standard Storm Water Requirements such as source control and low impact development BMP's required for all development projects. A Storm Water Management Plan {SWMP) is not required with your application{s) for development. Go to step 4 at the end of this questionnaire, check the "my project does not meet PDP requirements" box and complete applicant information. E-34 Page 2 of3 Effective 6/27/13 -.. -SITE INFORMATION CHECKLIST --Project Sum111pty tnl9tm~ticm •. I -Proiect Name Martin Residence Project ID HMP 15-01 -Project Address Adams Street -Carlsbad CA 92008 --Assessor's Parcel Number(s) (APN(s)) 206-200-03 -Project Watershed (Hydrologic Unit) Carlsbad 904.31 -Parcel Area 0.47 Acres (20,347 SQuare Feet) --Existing Impervious Area (subset of Parcel 0 Acres (0 Square Feet) Area) -Area to be disturbed by the project (Project 0.24 Acres (10,299 Square Feet) Area) -Project Proposed Impervious Area (subset of 0.20 Acres (8,415 Square Feet) Project Area) --Project Proposed Pervious Area ( subset of 0.04 Acres (1,884 Square Feet) Project Area) 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 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]: In the existing condition, the site generally drains over natural landscape to the South down a hillside with a slope of 4: 1 or less. The site drains directly to the Agua Hedionda Lagoon, and the Southerly boundary of the site extends roughly 47 feet South of the mean high tide line. There is no cross lot drainage to the West and minimal cross lot drainage to the East. There is onsite drainage from the North, over a slope in the Adams Street right-of-way. There is no onsite drainage from impervious areas. The project proposes to construct a single family residence and attached garage with an 'S' shaped driveway. Stairs and concrete walkways will provide access on the East and West sides of the residence to the lower level patio and pool on the South side of the residence. A multi-level pad will be cut into the hillside, with retaining walls to support the change in grade. The proposed development does not extend into the 100' wetland buffer. Grades along the North property line will be adjusted to eliminate any onsite drainage from the North, and a pervious concrete sidewalk will be constructed in the right-of-way to reduce the impervious footprint. Runoff from the proposed roof and hardscape will be diverted to various planters around the residence. These planters will be built to function as biofiltration basins, and runoff from all the biofiltration basins will be collected in a vault under the lower level patio. An outlet structure built into the vault will provide proper hydromodification and flood control of the treated waters. Output from the vault will be routed to a slotted PVC pipe laid level and surrounded by gravel to mimic sheet flow. Treated flow from the developed area will comingle with the wetland buffer area flow prior to flowing into the Agua Hedionda Lagoon. -- -·. ' , ldentificatitirfof Receivin'""FWater Pollutants·of.Qe>ncern I '.. .. .;"·, .. .,,, •• , • ••"• .u'.'', •·· ·••·''.•h•'•g••·''•••• '· '.h'"••-,,.,,.,., .•. ,, ,,· •••••=••• · Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or -reservoir, as applicable): -This site drains directly to the Agua Hedionda Lagoon. -.. 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 Indicator bacteria low Sedimentation/siltation -Pacific Ocean Coliform bacteria low --.. --Identification of Project Site Pollutants Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see -BMP Desion Manual Ap ::iendix B.6): -Also a Receiving Not Applicable to Anticipated from the Water Pollutant of -Pollutant the Project Site Project Site Concern X X -Sediment -X Nutrients -X Heavv Metals -X -Oroanic Compounds X -Trash & Debris -Oxygen Demanding X Substances -X -Oil & Grease -X X Bacteria & Viruses -X Pesticides ------ ------------------------ ----------- .·. . .. , • ttyg_rpmpdif!~oJMloJdiim,ot.::RiAYlim.ili~i,: .. I 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): Critical Coarse Sediment Yielg Area•* I *This Section only required if hyclromodific:atioh·managementreqJJirements 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 D 6.2.2 Downstream Systems Sensitivity to Coarse Sediment □ 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite D No optional analyses performed, the project will avoid critical coarse sediment yield areas identified based on WMAA maps If optional analyses were performed, what is the final result? □ No critical coarse sediment yield areas to be protected based on verification of GLUs onsite D Critical coarse sediment yield areas exist but additional analysis has determined that protection is not required. Documentation attached in Attachment 8 of the SWQMP. D Critical coarse sediment yield areas exist and require protection. The project will implement management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas are identified on the SWQMP Exhibit. Discussion I Additional Information: --. > .. soun;e cc.1ntrol. RealairemenHcont111uijdl . AooUed? -SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and □Yes □No Ill NIA Wind Dispersal -Discussion/justification if SC-4 not implemented: No outdoor work areas are proposed for this site. ----SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Ill Yes ONo 0 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 Quidance). -□ On-site storm drain inlets Ill Yes D No 0 N/A -□ Interior floor drains and elevator shaft sump pumps □Yes □No 111 N/A □ Interior parking garages □Yes □No 111 N/A -□ Need for future indoor & structural pest control ll)Yes □No 0 N/A -□ Landscape/Outdoor Pesticide Use ■Yes D No D NIA -□ Pools, spas, ponds, decorative fountains, and other water features ll)Yes □No 0 N/A D Food service □Yes □No 111 N/A □ Refuse areas □Yes 0 No Ill N/A -D Industrial processes □Yes □No 111 N/A -□ Outdoor storage of equipment or materials □Yes □No 111 N/A □ Vehicle and Equipment Cleaning □Yes 0 No 111 NIA -D Vehicle/Equipment Repair and Maintenance □Yes ONo 111 NIA -D Fuel Dispensing Areas □Yes D No Ill N/A D Loading Docks □Yes □No Ill NIA -D Fire Sprinkler Test Water □Yes 0 No 0 N/A D Miscellaneous Drain or Wash Water Ill Yes □No D NIA □ Plazas, sidewalks, and parking lots □Yes □ No 111 NIA -For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No" answers. - -------E-36 Page 2 of 4 Revised 09/16 - ,, Site Design Realilrement (continued) I AoQUed? SD-6 Runoff Collection I ■Yes I □ No I□ NIA -Discussion/justification if SD-6 not implemented: -----SD-7 Landscaping with Native or Drought Tolerant Species I Ill Yes I □No I □ N/A Discussion/justification if SD-7 not implemented: -----SD-8 Harvesting and Using Precipitation I □Yes I □ No I III NIA Discussion/justification if SD-8 not implemented: The site area is too small to implement harvesting in a cost effective manner. -.., --- - - - ,_ ---- ,. --.... ---~-"IR P:,nA .4 nf .4 CIAuict:M n011 a: --------• ---.. - ---- --- ---- ------ - 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 Contents Checklist Sequence Attachment 1 a DMA Exhibit (Required) See DMA ■ Included Exhibit Checklist on the back of this Attachment cover sheet. (24"x36" Exhibit typically required) Attachment 1 b Tabular Summary of DMAs Showing ■ Included on DMA Exhibit in DMA ID matching DMA Exhibit, DMA Attachment 1 a Area, and DMA Type (Required)* □ Included as Attachment 1 b, *Provide table in this Attachment OR separate from DMA Exhibit on DMA Exhibit in Attachment 1 a Attachment 1 c Form 1-7, Harvest and Use Feasibility • Included Screening Checklist (Required unless tJ Not included because the entire the entire project will use infiltration project will use infiltration BMPs BMPs) Refer to Appendix B.3-1 of the BMP Design Manual to complete Form 1-7. Attachment 1 d Form 1-8, Categorization of Infiltration D Included Feasibility Condition (Required unless □ Not included because the entire the project will use harvest and use project will use harvest and use BMPs) Refer to Appendices C and D of BMPs the BMP Design Manual to complete Form 1-8. Attachment 1 e Pollutant Control BMP Design ■ Included Worksheets I Calculations (Required) Refer to Appendices B and E of the BMP Design Manual for structural pollutant control BMP design guidelines ---ATTACHMENT la -- • ---- - -------- --- ------- - ATTACHMENT le 11111 - ----- -- - ~ - - -- - ATTACHMENT ld ,.. --- ---.. -------- - ATTACHMENT le - 1 2 3 4 5 6 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV ., -. --· --- Design Capture Volume Worksheet B-2.1 85th percentile 24-b.r storm depth from Figure B.1 -1 d= 0,6 inches Area tributary to BMP (s) A= 0 .7..Lf acres Area weighted runoff factor (estimate using Appendix 0.75 B.1.1 and B.2.1) C= unitless Tree wells volume reduction TCV= 0 cubic-feet Rain barrels volume reduction RCV= (J cubic-feet Calculate DCV = (3630 x C x d x A) -TCV -RCV DCV= 3 ~2 cubic-feet B-10 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV IMP 1 Design Capture Volume Worksheet B-2.1 1 85th percentile 24-hr storm depth frotn Figure B.1-1 d= 0.60 inches 2 Area tributary to BMP (s) A= 0.014 acres Area weighted runoff factor (estitnate using Appendix 3 B.1.1 and B.2.1) C= 0.90 unitless 4 Tree wells volume reduction TCV= 0 cubic-feet 5 Rain barrels volume reduction RCV= 0 cubic-feet Calculate DCV = 6 (3630 x C x d x A) -TCV -RCV DCV= 27 cubic-feet B-10 February 2016 • Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs IMP 1 ~ IPAUll 19,'fi • •ni■n1.-,ili'I . a.t.ning DCV after implementing retention BMPs 27 cubic-feet Partial Retention 2 Infiltration rate from Form I-9 if partial infiltration is feasible 0 in/hr. 3 Allowable drawdowo time for aggregate storage bdow the uoderdrain 36 hours 4 Depth of runoff that can be infiltrated [Line 2 x Line 3] 0 inches 5 Aggregate pore space 0.40 in/in 6 Required depth of gravd below the underdrain [Line 4/ Line 5] 0 inches 7 Assumed surface area of the biofiltratioo BMP 44 sq-ft 8 Media retained pore storage 0.1 in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 8 cubic-feet 10 DCV that requires biofiltration [Line 1 -Line 9] 19 cubic-feet BMP Parameters 11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches 12 Media Thickness [18 inches minimum], also add mulch layer thickness to 21 inches this line for sizing calculations 13 Aggregate Storage above uoderdrain invert (12 inches typical) -use 0 inches for sizing if the aggregate is not over the entire bottom surface area 6 inches 14 Media available pore space 0.2 in/in 15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control; 5 in/hr. if the filtration is controlled by the outlet, use the outlet controlled rate) Baseline Calculations 16 Allowable Rau ting Time for sizing 6 hours 17 Depth filtered during storm [Line 15 xLine 16] 30 inches 18 Depth of Detention Storage 12.6 inches [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 19 Total Depth Treated [Line 17 + Line 18] 42.6 inches Option 1-Biofilter 1.5 times the DCV 20 Required biofiltered volume [1.5 x Line 10] 29 cubic-feet 21 Required Footprint [Line 20/ Line 19] x 12 8 sq-ft Option 2 -Store 0.75 of rem<>; ... ;.,.0 DCV in pores and pon~ 22 Required Storage (surface+ pores) Volume [0.75 xLine 10] 14 cubic-feet 23 Required Footprint [Line 22/ Line 18] x 12 13 sq-ft Footprint of the BMP 24 Area draining to the BMP 616 sq-ft 25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.90 26 Minimwn BMP Footprint [Line 24 x Line 25 x 0.03] 17 sq-ft 27 Footprint of the BMP = Maximum(Minimum(Llne 21, Line 23), Line 26) 17 sq-ft Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area m Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) B-26 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV IMP2 Design Capture Volume Worksheet B-2.1 1 ssm percentile 24-hr storm depth from Figure B.1 -1 d= 0.60 inches 2 Area tributary to BMP ( s) A= 0.012 acres Area weighted runoff factor (estimate using Appendix 3 B.1.1 and B.2.1) C= 0.90 unitless 4 Tree wells volume reduction TCV= 0 cubic-feet 5 Rain barrels volume reduction RCV= 0 cubic-feet Calculate DCV = 6 (3630 x C x d x A) -TCV -RCV DCV= 24 cubic-feet B-10 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV IMP 3 -- Design Capture Volume Worksheet B-2.1 -.. 1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.60 inches 2 Area tributary to BMP (s) A= 0.034 acres Area weighted runoff factor (estimate using Appendix 3 B.1.1 and B.2.1) C= 0.86 unitless 4 Tree wells volume reduction TCV= 0 cubic-feet 5 Rain barrels volume reduction RCV= 0 cubic-feet Calculate DCV = 6 (3630 x C x d x A) -TCV -RCV DCV= 64 cubic-feet B-10 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV IMP4 il ;-·:--, ·-ri~~i,gp{:-;pt~i-v~,~~~~ -, -~ ·-.--,.~ . • ' -• 'I -· -. ~-:;----~-,. \ Worksheet-B-2.1 :,'f, ~ --.. ---• • ---~ ..._~----..: -·--'; ---.!.. -· ·-.. ~ , r•t_;;._..._~~----.... ! , ... ~.--'t "t..!.-~ 1 85th percentile 24-hr storm depth frotn Figure B.1-1 d= 0.60 inches 2 Area tributary to BMP (s) A= 0.086 acres Area weighted runoff factor ( estimate using Appendix 3 B.1.1 and B.2.1) C= 0.90 uoitless 4 Tree wells volume reduction TCV= 0 cubic-feet 5 Rain barrels volume :reduction RCV= 0 cubic-feet Calculate DCV = 6 (3630 x C x d x A) -TCV -RCV DCV= 169 cubic-feet B-10 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.2-1. DCV IMPS ------------------ Design Capt~re v_ olume Worksheet B-2.1 - 1 85th percentile 24-ht storm depth &om Figure B.1-1 d= 0.60 inches 2 Area tributary to BMP (s) A= 0.025 acres Area weighted runoff factor ( estitn.ate using Appendix 3 B.1.1 and B.2.1) C= 0.90 unitless 4 Tree wells volume reduction TCV= 0 cubic-feet 5 Rain barrels volume reduction RCV= 0 cubic-feet Calculate DCV = 6 (3630 x C x d x A) -TCV -RCV DCV= 49 cubic-feet B-10 February 2016 Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs IMP 5 ~ ll•:.iili111■-•I ..... , .. , •• _ :il~I • linlil• •• ·,,'-~ 1 Remaining DCV after implementing retention BMPs 49 cubic-feet Partial Retention 2 Infiltration rate from Form I-9 if partial infiltration is feasible 0 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] 0 inches 5 Aggregate pore space 0.40 in/in 6 Required depth of gravel below the underdrain [Line 4/ Line 5] 0 inches 7 Assumed surface area of the biofiltration BMP 38 sq-ft 8 Media retained pore storage 0.1 in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12) x Line 7 7 cubic-feet 10 DCV that requires biofiltration [Line 1 -Line 9] 42 cubic-feet BMP Parameters 11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches 12 Media Thickness [18 inches minimum], also add mulch layer thickness to 21 inches this line for sizing calculations 13 Aggregate Storage above underdrain invert (12 inches typical) -use 0 inches for sizing if the aggregate is not over the entire bottom surface area 6 inches 14 Media available pore space 0.2 in/in 15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control; 5 in/hr. if the filtration is controlled by the outlet, use the outlet controlled rate) Baseline Calculations 16 Allowable Routing Time for sizing 6 hours 17 Depth filtered during storm [ Line 15 x Line 16] 30 inches 18 Depth of Detention Storage 12.6 inches [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 19 Total Depth Treated [Line 17 + Line 18) 42.6 inches Option 1-Biofilter 1.5 times the DCV 20 Required biofiltered volume [1.5 x Line 10] 63 cubic-feet 21 Required Footprint [Line 20/ Line 19] x 12 18 sq-ft Option 2-Store 0.75 ofrem~•n~ ..... DCV in pores and ponding 22 Required Storage (surface+ pores) Volume [0.75 x Line 10] 32 cubic-feet 23 Required Footprint [Line 22/ Line 18] x 12 30 sq-ft Footprint of the BMP 24 Area draining to the BMP 1,086 sq-ft 25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.90 26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 29 sq-ft 27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 29 sq-ft Note: Line 7 is used to estimate the amount of volume retained by tbe BMP. Update a sumed surface area Ill Line 7 uotil its equivalent to tbe required biofiltratioo footprint (either Line 21 or Line 23) B-26 February 2016 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 Contents Checklist Sequence Attachment 2a Hydromodification Management ■ Included Exhibit (Required) See SWMMM Modeling Memorandum dated November 30, 2016 from Tory R. Walker Engineering for sizing and hydromodification calculations (included as a separate attachment) Attachment 2b Management of Critical Coarse ■ Exhibit showing project drainage Sediment Yield Areas (WMAA Exhibit boundaries marked on WMAA Critical is required, additional analyses are Coarse Sediment Yield Area Map optional) (Required) See Section 6.2 of the BMP Design Optional analyses for Critical Coarse Manual. Sediment Yield Area Determination □ 6.2.1 Verification of Geomorphic Landscape Units Onsite □ 6.2.2 Downstream Systems Sensitivity to Coarse Sediment D 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite Attachment 2c Geomorphic Assessment of Receiving ■ Not performed Channels (Optional) o Included See Section 6.3.4 of the BMP Design Manual. Attachment 2d Flow Control Facility Design and D Included Structural BMP Drawdown Calculations (Required) See Chapter 6 and Appendix G of the BMP Design Manual ATTACHMENT 2a ATTACHMENT 2b ATTACHMENT 3 Structural BMP Maintenance Information Use this checklist to ensure the required information has been included in the Structural BMP Maintenance Information Attachment: Preliminary Design/Planning/CEQA level submittal: Attachment 3 must identify: ■ Typical maintenance indicators and actions for proposed structural BMP(s) based on Section 7. 7 of the BMP Design Manual Final Design level submittal: Attachment 3 must identify: o Specific maintenance indicators and actions for proposed structural BMP(s). This shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect actual proposed components of the structural BMP(s) o How to access the structural BMP(s) to inspect and perform maintenance D Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds) D Manufacturer and part number for proprietary parts of structural BMP(s) when applicable □ Maintenance thresholds for BMPs subject to siltation or heavy trash(e.g., silt level posts or other markings shall be included in all BMP components that will trap and store sediment, trash, and/or debris, so that the inspector may determine how full the BMP is, and the maintenance personnel may determine where the bottom of the BMP is . If required, posts or other markings shall be indicated and described on structural BMP plans.) D Recommended equipment to perform maintenance □ When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management