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CT 12-01; Miles Pacific Subdivision; Storm Water Management Plan; 2015-06-26
fl: (Project No. CT 12-01/PUD12-08/CDP 12-15 - MILES- PACIFIC) A(^2> "^l^ CITY OF CARLSBAD ENGINEERING DIVISION PRIORITY DEVELOPMENT PROJECT STORM WATER MANAGEMENT PLAN NO. 14-10 FOR MiUi 7AC»FICS»^BP. CT 12-01/PUD 12-08/CDP 12-15 2373 PIO PICO DRIVE ENGINEER OF WORK ^t?^nald L. Holloway R.C.E 29271- EXP 3-31-17 Date ^''fj- 29271 PREPARED FOR: N£^ CAUV:5/SHEA HOMES LIMITED PARTNERSHIP 9990 Mesa Rim Road, Suite 200 San Diego, CA 92121 Phone: 858-526-6554 PREPARED BY: bhA, Inc. lantd planning, civil engineering, surveying 5115 Avenida Encinas, Suite L Carlsbad, CA 92008-4387 (760) 931-8700 W.O. 452-1224-600 MM May 24, 2012 Revised November 15, 2012 Revised June 11,2014 Revised May 5, 2015 Revised June 26, 2015 d O o < Q. TABLE OF CONTENTS Introduction I.A. Project Description I.B. Existing Site features and Conditions l.C. Proposed land use and anticipated activities affecting Stormwater l.D. Opportunities and constraints for Stormwater control and Treatment I.E. Nearby water bodies Applicable Stormwater Standards 11.A. Completed Stormwater Standards Questionnaire (SWSQ) II.B. HMP Applicability Determination III. Identification of Poiiutants of Concern III.A. Identification of Pollutants Generated by Land Use Type III.B. Project Hydrologic Location III.C. Identification of 303(d) Impaired Receiving Waters III.D. Beneficial uses of receiving water III.E. Identification of Primary Pollutants of Concern IV. Source Control Measures IV.A. Site activities and potential sources of pollutants IV.B. Permanent source controls, and operational source controls V. Low Impact Development (LID) Project Design Strategies V.A. Optimization of Site Layout V.A. 1. Limitation of development envelope V.A.I. Preservation of natural drainage features V.A.I. Setbacks of creeks, wetlands, and riparian habitats V.A. 1. Minimization of imperviousness V.A.I. Using drainage as design element CT 12-01, 2373 Pio Pico Drive bUlK, Inc. Project Number CDP 12-15 land planning, civil engineering, sun/eying Priority Development Storm Water Management Plan Page 1 TABLE OF CONTENTS (continued) V.B. Layout and use of permeable pavements or other pervious surfaces V.C. Dispersal of runoff from impervious areas to pervious areas V. D. Drain Impervious Surfaces to Engineered TCBMP's or IMP's VI. Integrated Management Practices (IMPs) VI. A. Selection process for IMPs targeting pollutants-of-concern VLB. Sizing factors for IMPs VI.B.l. Lower flow threshold determination VI.B.2. HMP Decision Matrix VI.C. Geotechnical recommendation on soil infiltration rates VI.D. Infiltration calculation (drawdown time) for any self-retaining areas serving as an IMP IX. Documentation of Stormwater Design IX.A. Drainage Management Areas IX.B. Print-outs from BMP sizing calculator IX.C. Tabulations IX.C. 1. Self-treating areas IX.C.2. Self-retaining areas IX.C.3. Areas draining to self-retaining areas IX.C.4. Areas draining to IMPs/TCBMPs IX.C.5. Sizing Calculations CT 12-01, 2373 Pio Pico Drive bh A, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 2 TABLE OF CONTENTS (continued) X. BMP Facility Maintenance Requirements X.A. Description of ownership and responsibility of maintenance X.B. Summary of maintenance requirements for each stomiwater Facility XI. SWMP Certification Statements XI.A. Preparer's statement XI.B. Owner's statement Attachments DMA/IMP sizing Exhibit Single sheet post-construction BMP Exhibit Single sheet post-construction DMA Exhibit "Preliminary Geotechnical Evaluation... 2375 Pio Pico Drive, Carlsbad" dated October 2012 by GeoSoils, Inc. CT 12-01, 2373 Pio Pico Drive bU^, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 3 Introduction This Storm Water Mitigation Plan (SWMP) is required under the City of Carlsbad ordinances. The purpose of this SWMP is to address the water quality impacts from the development of 2373 Pio Pico Drive, City of Carlsbad. The goal ofthe SWMP is to ensure that this project complies with the current Califomia Regional Water Quality Control Board's requirements. This goal will be achieved by developing and implementing practicable policies to ensure to the maximum extent practicable that redevelopment does not increase pollutant loads from the project site and considers urban runoff flow rates, durations, and velocities. Best Management Practices (BMPs) and Integrated Management Practices (IMPs) will be utilized to provide a long-term solution to water quality and flow control. This SWMP is intended to ensure the effectiveness of the BMPs through maintenance that is based on long-term planning. This SWMP is subject to revisions as needed to accommodate changes to the project design, or as required by the City and/or Engineer. I.A Project Description The project as proposed intends to develop the existing Single Family Residence, and existing greenhouse operations at 2373 Pio Pico Drive, City of Carlsbad (APN 156-351- 03, 07, and 08). The proposed development will consist of the demolition ofthe existing green houses, remedial grading, rough and fine grading, retaining walls, public street, storm drain, utility improvements construction, and the ultimate construction of 17 Single Family Residences. The redevelopment will create 95,983 square feet of impervious area. This value represents the curbs and gutters, street paving, driveways, and roof areas. Driveway areas are assumed to be 800 square feet for each lot, and the roof areas are assumed to be 2600 square feet each. See the next page for Vicinity Map. CT 12-01,2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 4 VICINITY MAP CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 5 I.B Existing Site features and Conditions The site is currently being used in greenhouse growing operations, and as a residential \7 l« y i ' J ^ I i r- \ t// site with one single family residential dwelling existing on site. f^'nik.i'^A'YV.M I ^ The existing improvements on the site consist of a 60'X^^©*^oncrete driveway, "" ' '"^ / '^"C approximately 2000 sq.ft. roof top, and dirt access dijvts to the shade cloth covered growing areas. For the purpose of the hydrologj^j^j^fi^ulations and this SWMP, the entire project area is considered developed to th^O DU/acp or less density. The slope ofthe land on the subject property and that of the surrounding properties is moderately sloping and generally flows from east to west. There are myriad storm drain pipes, drainage ditches and catch basins along Pio Pico that serve to intercept flows from the westerly sloping area east of Pio Pico, and convey them southerly toward Las Flores Drive. Interstate 5 borders the project on its westerly property line. The on-ramp to 1-5 North at Las Flores Drive is the nearest improvement to the west of the project. A concrete brow ditch runs along the top of the cut slope along the on-ramp that intercepts all westerly sfromwater flows and conveys them northerly toward Buena Vista Lagoon. All of the stormwater originating on the project site and other offsite tributary areas flow westerly to and are intercepted by this brow ditch. No signs of erosion or standing water were observed on the site during the field reconnaissance performed in March 2012. There are no contiguous natural weflands, watercourses, seeps, or springs. The Soil Type for the Project and the offsite-landscaped park is Type "B" with high permeability based on the Web Soil Survey Report (see Preliminary Drainage Study for this Proje^3tii^edJ[ictQfeaLl^8^ 2011 by National Rftsniiry^«; rnn«Prx/atinn Service (USDA). yroig) B soils having a moggimeiyiasr^ ratAvhen thoroughly wet. / .11-, • ! - jl "f\... „ '' CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 6 I.C Proposed land use and anticipated activities affecting Stormwater The proposed project proposes the development of 17 new single family residences including the requisite access roads, driveways, landscaping and treatment/detention basins. It is anticipated that these improvements will create 95,983 square feet of impervious area. The proposed disturbed area will be approximately 6.2 acres, which includes about 0.8 acres of offsite grading to provide cover over a proposed public sewer line extension. The proposed drainage pattem will be the same as the existing drainage pattem with some modifications to incorporate the Best Management Practices (BMPs) and Hydromodification into the project design to mimic the impacts on storm water quality and greatiy reduce quantities. The proposed runoff from the residential pads and sfreets will be captured and conveyed via storm drains to either Detention/Treatment Basin A or B. The bioretention sizing analyses are included in Section EX.B using the bioretention plus vault option. The bioretention basins have been designed with a minimum siuface depth of 2.7 feet in Basin A and 3.0 feet in Basin B. The IMPs are comprised of an 18-inch layer of amended soil (a highly sandy, organic rich compost with an infilfration capacity of at least 5 inches/hr) and a 40-inch layer of gravel in Basin A and a 42-inch layer of gravel in Basin B for additional detention to accommodate the French drain system. Below the gravel layer the basins are lined to prevent infilfration into the underlying soil. Flows will discharge from each basin via low flow orifice outlet from a 4-inch perforated pipe within the gravel layer to the receiving outlet storm drain pipe. The outlet pipes will discharge to a new catch basin that will be installed at the south-west comer of the property. The catch basin will connect to a storm drain system and discharge into the existing brow ditch within the Cal-Trans right of way. A riser structure will be constructed within the IMPs with a 3"-dia orifice set 6- inches above the bottom of the basin, and an emergency overflow set 29-inches (2.4 feet) above the bottom of the basin, such that peak flows can be safely discharged to the receiving storm drain system (see dimensions in the DMA/IMP Sizing Exhibit in Attachments). This system will control the discharge such that the peak flows will be substantially reduced. The treatment basins are designed as a bio-retention plus vault system with Hydromodification, and are sized using the HMP sizing factors from Table 4-10 of the County of San Diego SUSMP. The basins have been sized to accommodate 4% of the proposed impervious area in the basin area for a total of 4,279 square feet in Basin A and 5,352 square feet in Basin B, as well as 34% of the impervious area in Vi storage volume for a total of 15,918 cubic feet in Basin A and a total of 20,338 cubic feet in Basin B. The County of San Diego's Final HMP states that the ponding layer (surface volume) and gravel storage layer (subsurface volume) can be converted to volumes "so that the project designer can flexibly configure the ponding layer and storage layer to meet site constraints" (see excerpt in Attachments). This has been shown on the plans for the 2373 Pio Pico Project. For instance. Basin A will be configured with a 29-inch ponding layer above the CT 12-01,2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 7 surface for storage volume, and an 18-inch layer of amended soil plus a 40-inch gravel layer with a 40% void ratio below the surface for subsurface volume. Basin B will be configured with a 29-inch ponding layer above the surface for storage volume, and an 18- inch layer of amended soil plus a 42-inch gravel layer with a 40% void ratio below the surface for subsurface volume. The sum of the surface and subsurface storage volume meets the vault volume (Vi storage) requirements of 15,813 cubic feet for Basin A as well as 20,220 cubic feet for Basin B as illustrated in the DMA/IMP Sizing Exhibit (see Attachments). This sizing requirement creates basins that are vastly oversized for the purpose of Delta Q detention, but that is to the downstream properties advantage and benefit due to the overall reduction in storm water runoff quantity. The Storm Water quality is met to a high order by the use of the proposed bio-retention plus vault facilities with hydromodification. The treatment and hydromodification sizing for Basin A and Basin B were calculated using the BMP Calculator from Brown and Caldwell. The lower flow threshold of 0.1Q2 was selected. Both bioretention basins will release treated and detained runoff through a single pipe into the existing brow ditch along the top of slope at the on ramp from Las Flores Drive to 1-5 North. The runoff from the landscaped area at the back of Lots 13, 11, 10 and 9 flow directly into a brow ditch that bypasses the treatinent basins. For this reason, flow to these areas has been minimized and landscaping has been designed to eliminate the need for pesticides and fertilizers. These features will allow this area to be designated as a Self-Treating Area and allowed to bypass the treatment facility. This proposed system is our professional recommendation based on the City of Carlsbad SUSMP Section 2 to choose the bioretention plus vault system with hydromodification since it is the most effective and most cost efficient BMP that meets the requirements of the Carisbad SUSMP. (See Section VI.A. Selection process for IMPs for more details). CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 8 I.D Opportunities and constraints for Stormwater control and treatment The purpose ofthis section is to identify the constraints and opportunities that may affect the site design and selection of treatment and flow-control facilities. Constraints for this Proiect would be: The project proposes single family residential dwellings constructed on lots that range from 7,500 sf to 13,000 sf The space available to install suitable private bio-retention basins is very limited. The historic drainage pattems are overiand flow westeriy to a concrete brow ditch along the top of a cut slope for the Las Flores 1-5 North on-ramp. Special precautions must be taken to ensure that the capacity of this brow ditch is not exceeded. This project proposes to collect overflow from the bioretention basin in the upstream property, also known as MS 11-02. The detention basin has been sized to attenuate peak flows during the 100 year frequency storm event based on the City of Carisbad SUSMP requirements Althou^ the basin meets the required storage volume to detain 100 year storm flow, any overflow from the basin is allowed to discharge into a catch basin at the southwest comer of the MS 11-02 project site and be conveyed via storm drain pipe westerly around the perimeter of the CT 12-01 project site. The storm drain pipe connects to the proposed outlet pipe of Basin A. This will require drainage easements along the perimeter of the project for the benefit of the individual project lot owners. Although the MS 11-02 project bioretention basin meets the required storage volume to detain the 100 year storm flow, any increase in storm water discharges will not adversely affect the cumulative CT 12-01 peak flows. Opportunities for this proiect would be: The porous nature of the Type B soils encourages infiltration and the implementation ofa bio-retention type of treatment system. However, this design will include an impermeable liner and underdrain pipe system per specifications on page 46 of the Preliminary Geotechnical Evaluation from GeoSoils, Inc. dated October 31, 2012. The slope ofthe project property allows for the concentration and community treatment of the mnoff from the entire site prior to discharge into the downstream conveyance systems. These proposed BMPs can then be easily maintained through the implementation of a Storm Water BMP Maintenance Agreement, and managed by a Home Owners Association. The existing downstream storm drain system, consisting of a brow ditch has sufficient capacity to convey the post project storm flow discharge since the detention basins are of sufficient size as to reduce the historic discharge rate. Calculations are provided in the project Drainage Study. This project manages to both treat and detain storm flows so as to benefit downstream receiving systems by reducing overall discharge rates, and provide a inc. CT 12-01, 2373 Pio Pico Drive bhA, Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 9 level of treatment that meets the Maximum Extent Practicable standard set forth in the City of Carisbad SUSMP. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 10 I.E Nearby water bodies The nearest Municipal Separate Storm Sewer System (MS4) for this Project is the existing concrete brow ditch within and along the Caltrans right of way for the on-ramp to 1-5 North at Las Flores Drive. According to the Water Quality Control Plan for the San Diego Basin prepared by the San Diego Regional Water Quality Control Board, the receiving water for the proposed project is the Buena Vista Lagoon located in El Salto Hydrologic Subarea (904.21), which is within Buena Vista Creek Hydrologic Area (904.20), part of the Carisbad Hydrologic Unit (904.00). See the Nearest receiving water map next page. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 11 San Diego Hydrologic Basin Planning area excerpt: ON PROJECT LOCATION CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 12 Applicable Stormwater Standards This project is a redevelopment project, which creates 95,982 square feet of impervious area and because it is housing subdivision of more than 10 dwelling units, creates more than 5,000 square feet of new paved area for streets, highways and freeways, and disturbs more than one (1) acre of land it is considered as a Priority Development Project (PDP). See the completed Storm Water Standards Questionnaire (SWSQ) at next page. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 13 ^ CITY Of CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 FaradayAvenue 750-602-2750 www.carlsbadca .gov INSTRUCTIONS: To address post-development poiiutants that may be generated from development projects, the City requires that new deveiopment and significant redevelopment priority projects incorporate Permanent aorm Water Best Management Practices (BMPs) into the project design per the Cit/s Standard Urban Stormwater IVIanagement Plan (SUSMP), To view the SUSMP, refer to the Engineering Standards (Volume 4, Chapter 2) at www.cartsbadca.gov/standards. Initially this questionnaire must be completed by the applicant in advance of submitting for a developnnent application (subdivision, discretionary permits and/or construction permrts). The results of the questionnaire determine the level of storm water standards that must be applied to a proposed deveiopment or redevelopment project. Depending on the outconne, your project will either be subject to 'Standard Stormwater Requirements' or be subject to addrtional 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 devebpment application. If staff determines that the questionnaire wos incorrectly filled out and is subject to more stringent storm water standards than initially assessed by you, this will result in the return ofthe 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 separate completed and signed questionnaire must be submitted for each new devetopment application submission. Only one completed and signed questionnaire is required wtien multiple development applfcattons 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 P/ease start by completing Step 1 and follow the instructions. Wtien completed, sign the form at the end and submit this with your application to the city. • :— '"J ,' TO BE COIIW>I.Ena> FOR AU PROJECTS To determine if your project is a pnonty development project, please ansv«r the following questions YES NO 1, Is your project UMITED TO constructing new or retrofitting paved sidewalks, btoycle 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 paved streets or roads; OR (3) designed and constructed with permeable pavements or surfaces in accordance with USEPA Green Streets guidance? X 2. Is your project UMITED 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 thc last box stating "my projecf does not meet PDP requirements" and complete applicant infonnation. If you answered "no" to both questions, then go to Step 2, £•34 Page 1 of 3 Effective 6/27/13 CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 14 STORM WATER STANDARDS Development Services Land Development Engineering 1635 Faraday Avenue ^ CITY OF CARLSBAD QUESTIONNAIRE Development Services Land Development Engineering 1635 Faraday Avenue ^ CITY OF CARLSBAD E-34 760-602-2750 www.carlsbadca.gov STEP 2 To determine if your project is a priority development project, please ansvrer the following questions: YES NO 1. Is your project a new development that creates 10,000 square feet or more of impervreus surfaces collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, and public devetopment projects on public or private land. X 2. Is your project creating or replacing 5,000 square feet or more of impervious surface collectively over the ent re project site on an existing site of 10,000 square feet or more of impervious surface? This indudes commercial, industriai, residenHal. mixed-use, and public development projects on public or private tand. X 3. Is your project a new or redevelopment project that creates 5,000 square feet or more of impen/ious 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 seiting prepared foods and drinks for immediate consumption. X 4, Is your project a new or redevetopment project that creates 5,000 square feet or more of impervious surface collectively over tine entire project site and supports a hillside development project? A hillside development project includes development on any natural slope that is twenty-five percent or greater. X 5. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collecdvely over the entire project site and supports a parking tot A parking lot is a land area a- facility for the temporary parking or storage of motor vehKles used personally for business or for commerce. X 6. Is your project a new or redevelopment project that aeates 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 streel, road, highway, freeway or driveway Is any paved impervious surface used for the transporfation af automobiles, trucks, motorcycles, and other vehicles. X 1. Is your project a new or redevetopment project that creates or replaces 2,500 square feet or more of impervtous surface coltectvely over the entire site, and discharges directly to an Environmentally Sensitive Area (ESA)? 'Discharging Directly to' indudes flow that is conveyed overland a distance of 200 feet or less from the prefect to the ESA, or conveyed in a pipe or open channel eny distance as an isolated flow from the project to the ESA (i.e. not commingles with flows from adjacent lands).' X 8. Is your project a new devetopment that supports an automotive repair shop? An automotive repair shop is a facility that is categorized in eny one of the fdlowing Standard Industial Classification (SIC) codes- 5013 5014. 5541, 7532-7534, or 7536-7539. X 9. Is your project a new devetopment that supports a retail gasoline outtet (RGO)? This category includes RGO's thai meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily Tratfic (ADT) of 100 or more vehicles per day. X 10.1s your project a new or redevetopment project that results in the disturbance of one or more acres of land and are expected to generate pollutants post consti'uction? X 11.1s your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of impervtous surface or (2) increases imper/ious surface on the property by more than 10%? X 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 suoh as source control and low impact devetopment BMP's. A Storm Water Management Han (SWMP) must be submitted with your application(s) for deveiopment. 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 devetopment project and are therefore subject to implementing only Standard Storm Water Requirements such as source control and tow impact devetopment BMP's required for all development projects. A Storm Water Management Plan (SWMP) is not required with your appltoatton(s) for devetopment. Go to step 4 at the end of this questionnaire, check the "my project does not meet PDP requirements" box and complete applicant infonnation. E-34 Page 2 ot 3 Effective 6/27/13 CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 15 STORM WATER Development Services land DcMtopimiit EnflnMrlni STANDARDS Development Services land DcMtopimiit EnflnMrlni CITY OF CARLSBAD QUESTIONNAIRE 163S F«r<day Avenue CITY OF CARLSBAD E-34 760-fi02-27SO www.c*rhb«lca.^ Ooe> Ihe i«M«*lo|im(nt praiact ratuR in Ihe GmaiM er nplKW^ H you anaiwed >M.-lh* ilfuctunl BMP* nquirad for Priority 1^^ Impaivtou* MKtac* and not Ih* wilt* devalopiranL Oo to Mop 4, chock ttio *ny praiMt moon POP nqulfmioitlt'' box and coaipM* apfiHeant InfcraiaUon. lfyouan««iered-no,'the«lnicfaHalBMP*wquir«dlorPtiorityDe»lopin*MP> Ootoalap4, chacmtio 'IBy >wl«ct watt POP iMiilwiiiwm' Dox mtl fmHtm WMXaiiit Itaiiiniloh. 69 My pfojad mMtt PRIORITY OEVBLOPMENT PROJECT (PDP) nquimnwnia and muat compV Wth addMoiwI MomiMltr criteria per Iw SUSMP and I umttnland I mat pwiiara a Slam WMar Managam^ I undf»l»«>d(tewconmi(hydfomBd<ict»)n) taqulranwiu may apply >o iwy (WB)«et Rataflo SUSMP lor dataUt • MyprcJacido**aa(aMatPOPmqi*wnafMandinuatenlyooinplyviMi«TANaU^ Iho SUSMP. As pait of Ihese mpiinnieirta. I WiH incorporalB low kiipaot davMopi^ Apptcant Intofmation and SignMufo Box Aecaaaora Pareal Numbar(4: lS<-i51-03. 15g-i51-07 t 15<-381-08 AfipficwilTHlti OWHKR DalK 2373 PIO PICO DBIVE m$BoxloraiyUttOiily CityConcuiMneo: By: Proiactia * EmiionfnmMly SansMva Anas Im^uda hut ai* mil Ihnllad to al Claan Waiw dasignalad a* Aim a( Spaeial Biolagieal SignKoaiieo by fto SM* Walar Raaoufoas ConM Bo^ San Diago Baain airf aiMndiMnla): vaalarbodiaa daaisnaMwih •)* nAfffi ba«^^ Coi*ol Board AWalar Q«aRy CorM Plan lor •« SM Dlago Bailn (1«M) and ainandinania); araoa daalg^^ qiivalani andar Vw Multl Spaciac Cansanalon Pngiam wMNn Iho CIMaa and ominnmonlaly aanaillf* aroaa which hav* boan IdaMIRad by Mw CopomiUaos. E-34 Pago3of3 EHKllwtar/tS CT 12-01.2373 Pk) Pico Drive Project Number CDP 12-15 Priority Development Storm Waler Management Plan bhA, Irx:. land planning, civil engineering, surveying Page 16 II.B HMP Applicability Determination Priority Development Projects (PDP) are required to implement hydromodification mitigation measures so that post-project runoff flow rates and durations do not exceed pre- project flow rates and durations where such increases would result in an increased potential for erosion or significant impacts to beneficial uses. Hydromodification refers to changes in the magnitude and frequency of stream flows as a result of urbanization and the resulting impacts on receiving channels in terms of erosion, sedimentation, and degradation of in-stream habitat. The degree to which a channel will erode is a fiinction of the increase in driving force (shear sfress), the resistance of the channel (critical shear stress), the change in sediment delivery, and the geomorphic condition ofthe channel. Critical shear stress is the stress threshold above which erosion occurs. Not all flows cause erosion ~ only those that generate shear sfress in excess ofthe critical shear stress of the bank and bed materials. Urbanization increases the shear stress exerted on the channel by stream flows and can trigger erosion in the form of incision (channel down cutting), widening (bank erosion), or both. Increases in flow below critical shear sfress levels have littie or no effect on the channel. In accordance with the Municipal Permit and final HMP, in addition to satisfying LID and treatment control (numeric) requirements, projects subject to PDP requirements might be required to implement measures so that post-development runoff rates and durations do not exceed pre-project conditions up to 10-year storm event only (hydromodification controls). This Project is a: PDP project Which increase the impervious area, Does not directly discharge to any of the exempt systems or lagoon area, Its stabilized conveyance system does not directly discharge to exempt system. Does not discharge to highly urbanized watershed, Not an urban infill. So based on the Figure 2-1 of the City of Carlsbad SUSMP, revised January 14, 2011, this project is subject to hydromodification control requirements. See the Figure 2-1 at next page. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 17 II.B HMP Applicability Determination (continued) Go to FlQOt B-2 ofOcoston Mal^ Figure 2-1. HMP Applicability Determination CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 18 III. Identification of Pollutants of Concern This SWMP identifies pollutants of concem in accordance with Section 2 of City of Carisbad's Standard Urban Storm Water Mitigation Plan (SUSMP) dated January 14 2011. In general urban mnoff from a developed site has the potential to contribute pollutants, including oil and grease, suspended solids, metals, gasoline, pesticides, and pathogens to the storm water conveyance system and receiving waters. For the purposes of identifying pollutants of concem and associated storm water BMPs, pollutants are grouped in nine general pollutant categories; Sediments, Nutrients, Metals, Organic Compounds, Trash, Oxygen-Demanding Substances, Oil and Grease, Bacteria and Vimses, Pesticides. See the Section 2 of the City of Carisbad SUSMP January 14, 2011 for definitions and details on each of these categories. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 19 III.A Identification of Pollutants Generated by Land Use Type Table 2-1 of the City of Carlsbad SUSMP associates pollutants with the categories of Priority Development Projects; Project Categories General Pollutant Categories r-Ti Detached Residential Development Sediment Nutrients Trash & Debris Oxygen Demanding Substances Oil & Grease Bacteria & Viruses Pesticides 1—1 Attached Residential Development Sediment Nutrients Trash & Debris Oxygen Demanding Substances (if landscape exists on-site) Oil & Grease (if uncovered parking areas exist on-site) Bacteria & Viruses Pesticides r~l Commercial Development Sediment (if landscape exists on-site) Nutrients (if landscape exists on-site) Heavy Metals Organic Compounds (if uncovered parking areas exist on-site) Trash & Debris Oxygen Demanding Substances (includes solvents) Oil & Grease Bacteria & Viruses (if land use includes food or animal waste products) Pesticides (includes solvents) 1—1 Heavy Industry or Industrial Development Sediment Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil & Grease CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 20 in.A Identification of Pollutants Generated by Land Use Type (Continued) Project Categories General Pollutant Categories r~l Automotive Repair Shop Heavy Metals Organic Compounds (includes petroleum hydrocarbons solvents) Trash & Debris Oil & Grease 1 1 Restaurants Trash & Debris Oxygen Demanding Substances Oil &. Grease Bacteria & Viruses Pesticides (if landscape exists on-site) O Hillside Development Sediments Nutrients Trash & Debris Oxygen Demanding Substances Oil & Grease Pesticides 1 1 Parking Lots Sediments (if landscape exists on-site) Nutrients (if landscape exists on-site) Heavy Metals Trash & Debris Oxygen Demanding Substances (if landscape exists on-site) Oil & Grease Pesticides (if landscape exists on-site) O Retail Gasoline Outlets Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil & Grease ^ Streets, Highways & Freeways Sediments Nutrients (if landscape exists on-site) Heavy Metals Organic Compounds (including petroleum hydrocarbons) Trash & Debris Oxygen Demanding Substances (includes solvents) Oil & Grease Bacteria & Viruses Pesticides (if landscape exists on-site) CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 21 III.B Project Hydrologic Location According to the Water Quality Control Plan for the San Diego Basin prepared by the San Diego Regional Water Quality Control Board, the receiving water for the proposed project is Buena Vista Lagoon located in El Salto Hydrologic Subarea (904.21), which is within Buena Vista Creek Hydrologic Area (904.20), part of the Carisbad Hydrologic Unit (904.00). Hydrologic Unit Hydrologic Area Hydrologic Sub-Area • Santa Margarita 902.00 • Ysidora 902.10 • Lower Ysidora 902.11 • San Luis Rey 903.00 • Lower San Luis 903.10 • Mission 903.11 • Bonsall 903.12 1^ Carisbad 904.00 • Loma Alta 904.10 El Buena Vista Creek 904.20 Kl El Salto 904.21 • Vista 904.22 • Agua Hedionda 4.30 • Los Monos 904.31 CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 22 III.C Identification of 303(d) impaired Receiving Waters This section is based on the Section 303(d) of 2010 Clean Water Act List of Water Quality Limited Segments Requiring TMDLS. At this time no further TMDL's have been established within Carlsbad. Receiving Water Poliutant(s) Causing Impairment 1^ Buena Vista Lagoon ^ 90421000 (0.15 Miles) Indicator Bacteria Nutrients Sedimentation/Siltation CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 23 iil.D Beneficial uses of receiving water Beneficial Uses of Coastal Waters Beneficial Uses Inland Surface Waters Hydrologic Unit Basin Number I N D N A V R E C R E C c 0 M B I 0 E s T w I L R A R M A R A Q u M I G S P W W A R s H L V 1 2 M L 1 D E M A R A R N M L Buena Vista Lagoon 904.21 X X X P X X X X X Existing Beneficial Use; P Potential Beneficial Use Beneficial Uses of Ground Waters Ground Waters El Salto HSA* Hydrologic Unit Basin Number 904.21 Beneficial Uses M A I P R 0 C F R c G U G N P R 0 C F R c W N R D P R 0 C H R X X P X Existing Beneficial Use; P Potential Beneficial Use * These beneficial uses do not apply westerly of the easterly boundary ofthe right-of-way of Interstate 5 and this area is exempted from the sources drinking water policy. The beneficial uses for remainder of the hydrologic area are as shown. CT 12-01,2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 24 iii.E identification of Primary Poiiutants of Concern Any pollutants identified in Table 2-1 of the SUSMP, which are also causing impairment of the receiving waters, shall be considered primary pollutants of concem. Pollutants not identified as primary pollutants are categorized as secondary pollutants of concem. Primary Poiiutants of Concem Secondary Poiiutants of Concem ^ Sediment n Sediment K Nutrients r~| Nutrients Q Heavy Metals ^ Heavy Metals r~l Organic Compoimds ^ Organic Compounds l~l Trash & Debris ^ Trash & Debris [H Oxygen Demanding Substances ^ Oxygen Demanding Substances • Oil & Grease 13 Oil & Grease ^ Bacteria & Viruses n Bacteria & Viruses 1 1 Pesticides ^ Pesticides CT 12-01,2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 25 IV. Source Control Measures Source Control BMPs are comprised of land use, site planning, structural or nonstructural measures which are intended to prevent the introduction of urban mnoff pollution to the storm water conveyance system by reducing the potential for contamination at the source of pollution. Directly following is the source control measures specifically selected for this project. The full general list follows this specific one. Potential Sources of Runoff Pollutants Permanent Controls Operational BMPs On-site storm drain inlets Mark all inlets with the words "No Dumping! Flows to Bay" or similar. Maintain and periodically repaint or replace inlet markings. Provide Stormwater pollution prevention information to new site operators. See applicable operational BMPs in fact sheet SC-44, "Drainage System Maintenance", and SD-13 "Storm Drain Signage" in the CASQ Stormwater Quality Handbooks at www.cabmphandbooks.com A copy of these fact sheets is in the References Section of this report as well. Landscape/Outdoor Pesticide Use (For parts of landscaped area which will be disturbed due to installation the IMPs) Preserve existing native trees, shmbs, and ground cover to the maximum extent possible. Design landscaping to minimize irrigation and mnoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to Stormwater pollution. Where landscaped areas are used to retain or detain Stormwater, specify plants that are tolerant Maintain landscaping using minimum or no pesticides. See appHcable operational BMPs in Fact Sheet SC-41, "Building and Ground Maintenance", in the CASQA Storm Water Quality Handbooks at www. cabmphandbooks .com Landscape/Outdoor Pesticide Use (For parts of landscaped area which will be disturbed due to installation the IMPs) Preserve existing native trees, shmbs, and ground cover to the maximum extent possible. Design landscaping to minimize irrigation and mnoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to Stormwater pollution. Where landscaped areas are used to retain or detain Stormwater, specify plants that are tolerant A copy of these fact sheets is in the References Section of this report as well. Provide IPM information to new operators. CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 25 of saturated soil condition. (The appropriate plants for bioretention facility are herbaceous plants, shmbs and/or small trees) Consider using pre-resistant plants, especially adjacent to hardscape. To insure successful establishment, select plants appropriate to site soils, slopes, climate, sun, wind, and rain. Land Use, air movement, ecological consistency, and plant interactions. Fire Sprinkler Test Water Provide means to drain Fire Sprinkler Test Water to Sanitary Sewer. See the note in Fact Sheet SC-41, "Building and Grounds Maintenance," in the CASQA Stormwater Quality Handbooks at vmw.sabmphandbooks.com Condensate Drain Lines Roofmg, Gutters, and Trim Condensate Drain Lines may discharge to landscaped areas if the flow is small enough that mnoff will not occur. Condensate drain lines may not discharge to the storm drain system. Avoid roofmg, gutters, and trim made of copper or other unprotected metals that may leach into mnoff. Sidewalks Sidewalks shall be swept regularly to prevent the accumulation of litter and debris. Debris from pressure washing shall be collected to prevent entry into the storm drain system. Washwater containing any cleaning agent or degreaser shall be collected and discharged to the sanitary sewer and not discharged to a storm drain. CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 26 IF THESE SOURCES WILL BE ON THE PROJECT SITE ... Potential Sources of Runoff Pollutants - List in Table 9 THEN YOUR STORMWATER CONTROL PLAN SHOULD INCLUDE THESE SOURCE CONTROL BMPs Permanent Controls—Show on Source Control Exhibit, Attachment B Permanent Controls—List in Table 9 and Narrative Operational BMPs—Include Table 9 and Narrative A. On-site storm drain inlets Locations of inlets. Mark all inlets with the words "No Dumping! Flows to Bay" or similar where feasible. Maintain and periodically repaint ot replace inlet markings. Provide stormwater pollution prevention information to new site owners, lessees, or operators. See applicable operational BMPs in Fact Sheet SC-44, "Drainage Systerr Maintenance," in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Include the following in lease agreements: "Tenant shall not allo-w anyone to discharge anything to storm drains or to store or deposit materials so as to create a potential discharge to storm drains." CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land pianning, civil engineering, surveying Page 27 IF THESE SOURCES WILL BE ON THE PROJECT SITE ... Potential Sources of Runoff Poiiutants - List in Tabie 9 THEN YOUR STORMWATER CONTROL PLAN SHOULD INCLUDE THESE SOURCE CONTROL BMPs Permanent Controls—Show on Source Control Exhibit, Attachment B Permanent Controls—List in Table 9 and Narrative Operational BMPs—Include in Table 9 and Narrative D2. Landscape/ Outdoor Pesticide Use Note: Should be consistent with project landscape plan (if applicable). • Show locations of native trees or areas of shrubs and ground cover to be undisturbed and retained. • Show self-retaining landscape areas, if any. Show stormwater treatment facilities. State that final landscape plans will accomplish all of the following: Preserve existing native trees, shrubs, and ground cover to the maximum extent possible. Design landscaping to minimize irrigation and runoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to stormwater pollution. Where landscaped areas are used to retain or detain stormwater, specify plants that are tolerant of saturated soil conditions. Consider using pest-resistant plants, especially adjacent to hardscape. To insure successful establishment, select plants appropriate to site soils, slopes, climate, sun, wind, rain, land use, air movement, ecological consistency, and plant interactions. Maintain landscaping using minimum or no pesticides. See applicable operational BMPs in Fact Sheet SC-41, "Building and Grounds Maintenance," in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Provide IPM information to new owners, lessees and operators. CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 28 *^ N. Fire Sprinkler Test Water • • • O. Miscellaneous Drain or Wash Watet Boiler drain lines Condensate drain lines Rooftop equipment Drainage sumps Roofing, gutters, and trim. y Provide a means to drain fire sprinkler test water to the sanitary sewer. Boiler drain lines shall be directly or indirectly connected to the sanitary sewet system and may not discharge to the storm drain system. Condensate drain lines may discharge to landscaped areas if the flow is small enough that runofif will not occur. Condensate drain lines may not discharge to the storm drain system. Rooftop mounted equipment with potential to produce pollutants shall be roofed and/or have secondary containment. Any drainage sumps on-site shall featute a sediment sump to reduce the quantity of sediment in pumped water. Avoid roofing, gutters, and trim made of copper or other unprotected metals that may leach into runoff. See the note in Fact Sheet SC-41, "Building and Grounds Maintenance," in the CASQA Stormwater Quality Handbooks at vyww.cabmphandbooks.com P. Plazas, sidewalks, and parking lots. Plazas, sidewalks, and parking lots shall be swept regularly to prevent the accumulation of litter and debris Debris from pressure washing shall be collected to prevent entry into th< storm drain system. Washwater containing any cleaning agent or degreaser shall be collected and discharged to the sanitary sewer anr' not discharged to a storm drain. CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 29 V. Low Impact Development (LID) Project Design Strategies The LID Strategies for managing mnoff from paving can provide multiple, complementary benefits to the project. Pervious surface reduce heat island effects and temperature extremes. Landscaping improves air quality, create a better place to live or work, and upgrades value for rental or sale. LID drainage design can also conserve water and reduce the need for drainage infrastmcture. All the Integrated Management Practices (IMPs) are designed based on the Section 4 of City of Carisbad SUSMP dated January 14, 2011. V.A. Optimization of Site Layout The site proposes removing all of the existing horticulture stmcmres and shade cloth and completely re-grading the entire site. There are no opportunities to preserve natural features as most all of the natural aspects of the site are long since removed. The general drainage pattem along with the storm water discharge location are maintained in the proposed residential development. V.B. Layout and use of permeable pavements or other pervious surfaces There will be no permeable pavement or pervious surface proposed for this project. V.C. Dispersal of runoff from impervious areas to pervious areas There will be two drainage inlets located at the low point of the proposed improvements (west end cul-de-sac) which will intercept, contain and convey the storm flow and treatment flow to the bioretention/detention basins. V.D. Drain Impervious Surfaces to Engineered TCBMP's or IMP's The storm water generated on the proposed development will be captured, detained and treated by a bio-retention basins sized for hydromodification and peak storm flow detention. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 30 VI. Integrated Management Practices (IMPs) Integrated Management Practices (IMPs) will be utilized in this project to provide a long- term solution to water quality and flow control. Vi.A. Selection process for IMPs targeting pollutants-of-concern The primary pollutants of concem for this project are sediments, nutrients, bacteria & vimses. This project proposes the use of bioretention basins to mitigate the pollutants of concem to the maximum extent practicable. A bioretention facility over B-Type soil consists of a stirface ponding layer and a growing medium layer. The facility capmres ranoff in a surface ponding layer, filters it through plant roots and biologically active soil mix, percolates water from the growing medium into a under-drain pipe which connects to an outlet stmcmre. This outlet stmcture controls the outflow to below historical values. As described in Section I.D Oppormnities and Constraints of this report, the IMPs/TCBMPs which would be proposed is dependent upon the soil type and available area for the treatment facility. For this project, bio-retention basins were chosen as the system best able to treat the ranoff to the maximum extent practicable, and provide the necessary storm water detention volume to attenuate the peak flows while also making sure the low flows are mitigated to meet the Carlsbad SUSMP HMP requirements. VLB. Sizing factors for IMPs The proposed bioretention plus vault facilities shall be sized for water quality treatment and also for the purpose of flow confrol and hydromodification requirements. This project will use the sizing factors of Table 4-10 of the County SUSMP to size the required bioretention plus vault facilities. Sizing factors are developed through the use of continuous simulation hydrologic modeling. Sizing factors are the ratio of the required mitigation size (in area or volume) as compared to the contributing developed area. The sizing factors are determined based on the amount of lower flow threshold, soil group, slope, and location of the site in comparison with rain gauge. The results from the BMP Calculator from Brown and Caldwell are also included in this report. VI.B.L Lower flow threshold determination The field investigations will not be conducted, and the SCCWRP channel screening tools are not completed for this project. Based on the City of Carlsbad SUSMP Section 2; the CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 31 site must mitigate peak flows and durations based on a pre-project condition lower flow threshold of0.1Q2. VI.B.2. HMP Decision Matrix This project is not using the SCCWRP screening tools and does not include infiltration to native soil per the specifications of the Preliminary Geotechnical Evaluation from GeoSoils Inc. Based on the matrix the bioretention facility will be sized for flow range of 0.1Q2 to QIO. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 32 Consult witti Geotechnical Engineer 4. Size LID and BMP Facilities for Flow Range of 0.1 Qj to Q,^? Redesign LID or BMP End of Dedsion Matrix Figure 6-2. Of Final HMP Mitigation Criteria and Implementation CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, c vil engineering, surveying Page 33 VI.C. Geotechnical recommendation on soil infiltration rates The bottom of the bioretention facilities will be lined with an impermeable liner and an underdrain pipe to prevent infiltration into the native soils. The Preliminary Geotechnical Evaluation from GeoSoils, Inc., dated October 31, 2012, specifies an impermeable liner be incorporated into the basin design. VI.D. Infiltration calculation (drawdown time) for any self-retaining areas serving as an IMP No Self-retaining areas were proposed for this project. Drawdown calculations for bioretention facilities are provided in the Preliminary Drainage Smdy for this site. For 2.4 feet of ponded depth in the basins and a bottom basin area of 4,279 sq. ft. in Basin A and a bottom basin area of 5,352 sq. ft in Basin B, flow through orifice plate govems drain- down flow. From the BMP Calculator, the drawdown time for a 1.50"-dia orifice place in Basin A is 20.2 hrs., and the drawdown time for a 1.50"-dia orifice place in Basin B is 24.8 hrs. Drawdown Calculations: Maximum potential surface volume: Basin A: 10,270 cf Basin B: 12,845 cf Orifice Flow from BMP Calculator (see SWMP Report): Basin A: 0.141 cfs Basin B: 0.144 cfs Time = Volume / Flowrate: Basin A: 72,836 sec = 20.2 hours < 72 hours ^ Basin B: 89,201 sec = 24.8 hours < 72 tiours Note: See Drainage Report associated with this Report for basin storage and outflow calculations. CT 12-01,2373 Pio Pico Drive bhA, Inc Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 34 IX. Documentation of Stormwater Design The stormwater classification for this project includes only areas draining to IMPs. IX.A. Drainage Management Areas The project site is divided into (2) Drainage Management Areas (DMAs). The DMAs are designed to address the treatment component of the mitigation plan consistent with the unified LID design approach. Summary of Project DMIAs DMA Type Number or DiMAs per Type Self-Treating Areas 1 Self-Retaining Areas 0 Areas That Drain to Self-Retaining Areas 0 Areas That Drain to Integrated Management Practices (IMPs) 18 Areas That Drain to Stmcmral Treatment Control BMPs 0 Areas That Drain to Proprietary Treatment Control BMPs 0 Total Number of DMAs 19 CT 12-01,2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 35 "D "D O —1 /Tl —^ O CD < o "O 3 CD 13 CO o —, 3 DJ CD =3 O) CQ CD 3 CD 03 O o I cn CD Z! CO. T3 CU 13' CQ O CD CQ ZD' CD CD —1 cp cr 03 <Q CD CD CO tSJ I o CO oo 33 o TJ o' o O —^ <• CD > ZJ n BMP Sizing Spread*eet VLM Projecl Name: CT 1201, 2373 Pio Pico Drive Hydrologic Unit: Project Applicant: Rain Gauge: Oceanside Jurisdiction: Total Project Area: Parcel (APN): low ftow "nreshold: aiQ2 BMP Name: Basin A BMP Type: Bioretention PkisVaiilt BMP Native Soil Type: B SMPInBllratlon Sate (In/hr): 0.52 Areas Draining to BMP HMP Sizing Factors Minimum BMP Size OMA Mame Area(sf) Soil Type Slope Post Proiect Surfece Tvpe Runoff Factor (Table «) Bioretention Surface Area Vault Volume N/A Bioretention Surface Area (sf) Vault Volume (cf) N/A DMA A B Moderate Roof LO 0.01 0.34 N/A 1622 13784 N/A 59S67 B Moderate Landscape 01 aoi 034 N/A 239 2029 N/A Total BMP Area 100207 Minimuftr BMP Size 1860 268 1,S812 Proposed BMP Size" 4279 N/A N/A In Minimum Vault Deptfr N/A in Maximum Vault Depth N/A in Selected Vault Oepth 68.40 in Selected \^ult Volume 15918 cuNc feet Describe (he BMP'sin aiffiderrt detail in your SWMP to demonstrate the area, volume, and otber criteria can be met within theconstraintsof the site. BMP'smii^t be adapted and applied to the conditions specific to the development project such as unstable dopes or the laclc of available head. Des'gnsted Staff have final revie wand approval authority over the project desiga Tlii^Simg Cfllnilator hasbeen develoocd in compliance with the Cotinty^Mde Model SUSMP. For questions or concerns please contact the jurisdiction In which your project islocated X "t o o 3 ss 5' tro rs 2-n" c_ 5" O -v -D a> E M. zn. CD o CD < CD_ o 3 CD cn o —1 3 21 CD CU <o CD 3 CD 2 13 CZ 3 o- CD —t O o TJ cn o PO oo oo TJ o' Tl o' o O CM 3 Q. CU 3 3 3' CQ O <' CD 3 CQ 3' CD CD 3' CQ C/3 TJ != BMP Sizing Spreadsheet Vl.04 Project Name: 12-01, 2373 Pio Pico Dr Hydrologic Unit: Project Applicant: Rain Gauge: Oceanside Jurisdiction: Total Project Area: Parcel (APN): Low Flow Threshold: 0.1Q2 BMP Name Basin A BMP Type: Bioretention Plus Vault DfulA Name Rain Gauge Existing Condition C12 Sizing Factor (cfs/ac) DMA Area (ac) Orifice Flow - WQj (cfs) Orifice Area (in21 DfulA Name Rain Gauge Soil Type Cover Slope C12 Sizing Factor (cfs/ac) DMA Area (ac) Orifice Flow - WQj (cfs) Orifice Area (in21 DMA A Oceanside B Scrub Moderate 0.134 0.931 0.012 0.17 Oceanside B Scrub Moderate 0.134 1.370 0,018 0.26 0.031 0.43 0.74 Tot. Allowable Orifice Flow (cfs) Tot. Allowable Orifice Area (in2) Max Orifice Diameter (in) 0.141 1.77 1.50 Actual Orifice Flow (cfs) Actual Orifice Area (in2) Selected Orifice Diameter (in) I (Hrs) I ' CQ CD CD c>3 3" ^ CQ TJ "D O =3. CD o CD < O 3 CD =3 ro 3 o-CD —1 o o T) ro cn oo ~j oo TJ o' TJ o' o CJ <.' CD BMP Sizing Spread*eet VL04 Project Nsine: CT 12-01,2373 Pio Pico Drive Hydrologic Urit: Project Applicant: Rain Gauge: Oceanside Jurisdiction: Total Project Area: Parcel (APN): low Flow Threshold: 0.1Q2 BMP Name: Basin B BMPType: Bioretention Plus Vault BMP Native Soil Type: B BMPInfiltration Rate (In/hr): 0.52 Areas Draining to BMP HMP Sizing Factors Minimum BMP Size DMA Name Area(sf) Soil Type Slope Post Project Surfece Type Runoff Factor (Table 4-2) Bioretention Surface Area Vaull Volume N/A Bioretention Surface Area (sf) Vault Volume (cf) N/A DMAB 54118 B Moderate Roof 10 004 0.34 N/A 2165 18400 N/A 53521 \ B , Moderate landscape 0.1 0.04 0.34 N/A 214 1820 N/A Total BMP Area 107639 Minimum BMP Size 237a804 20220 Proposed BMP Size* 5352 N/A N,'A in Minimmn Vault Depth N/A in Maximum Vault Depth N/A in Selected Vault Deptti 70.80 in Selected Vault Volume 20338 cubic feet CO o CP CD Q3 to CD 3 CD r3 =3 03 3 Q. "g_ 03 3 3 3" CQ O <^ CD 3 CQ 3" CD CD 5' CD C/3 03 5 CD ^ CO 3" OO CQ cr 3 o Describe the BMP'sin sufficient detail in your SWMP lo demonstrate the area, volume, and olher criteria can be met within the constraints of thc site. BMP'! must bc adapted and applied to thc conditions specific to the development project such asunstable dopes or the lack of available head. Oeggnated Staff have Rnal review and approval authority overthe project design. This Sizing Calculator hasbeen developed in compliance with the Countywide Model SUSMP. For questions or concerns please contact the jurisdiction in v/hich your project islocated. T) TJ o' O —t CD' o CD c veil mb o CD •o 3 CD o TJ cn o tV3 ^ Z3 cn CD 03 Z3 0) CQ CD 3 CD Z! "D 03 =3 o o ro oo oo TI o' TJ o' O land pl cr lanni Inc 3 O <^ CD CQ ineeri 3 CQ surveyi Page CO CQ BMP Sizing Spreadsheet Vl.04 Project Name: 12-01, 2373 Pio Pico Dr Hydrologic Unit: Project Applicant: Rain Gauge: Oceanside Jurisdiction: Total Project Area: Parcel (APN): Low Ftow Threshold: 0.1Q2 BMP Name Basin B BMP Type: Bioretention Plus Vault DMA Name Rain Gauge Existing Condition Q2 Sizing Factor (cfs/ac) DMA Area (ac) Orifice Ftow-%Qj (cfs) Orifice Area (in2) DMA Name Rain Gauge Soil Type Cover Slope Q2 Sizing Factor (cfs/ac) DMA Area (ac) Orifice Ftow-%Qj (cfs) Orifice Area (in2) DMA B Oceanside B Scrub Moderate 0.134 1.242 0.017 0.23 Oceanside B Scrub Moderate 0.134 1.229 0.016 0.23 Drawdown (Hrs) 0.033 0.46 0.76 Tot. AHowable Orifice Row (cfs) Tot. Allowable Orifice Area (in2) Max Orifice Diameter (in) 0.144 1.77 1.50 Actual Orifice Ftow (cfs) Actual Orifice Area (inZ) Selected Orifice Diameter (in) IX.C. Tabulations IX.C. 1. Self-treating areas ST-1 (3907 SF) as shown on Post-Construction BMP Exhibit, will be designated as a Self- Treating area through Landscape design and runoff flow minimization. IX.C.2. Self-retaining areas N/A IX.C.3. Areas draining to self-retaining areas N/A IX.C.4. Areas draining to IMPs/TCBMPs The IMPs are sized using methods described in Section 4 of the City SUSMP. Areas draining to IMPs are multiplied by a sizing factor to calculate the required minimum size ofthe IMP. The identification of DMA surface types and runoff factors are enumerated in the following Tabulation of Areas Draining to DMAs. The locations and limits of all Areas Draining to IMPs are delineated on the DMA Exhibit. See DMA/IMP Sizing Exhibit in the Attachments section of this report for detailed calculations, IX.C.5. Sizing Calculations This project will use the BMP Calculator to size the required bioretention plus vault facility. See the printouts on the previous page for the results. From Table 4-10: Sizing Factors for Bioretention Plus Vault Facilities from the County SUSMP, lower flow threshold is 0.1 Q2, slope is moderate between 5% and 10%, and the most appropriate rain gauge for this project is Oceanside. See next page for excerpt from Table 4-10. See also DMA/IMP Sizing Exhibit in Attachments. Detention Basin outlet details and flowrates are available in the Preliminary Drainage Study. Please see that Study for design parameters and facility sizing determinations. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 40 r j Lower f^low Threshold Soil Group Siope Rain Gauge | VI y2 0.1Q2 A Flat Oceanside N/A N/A N/A 0.1Q2 A Moderate Oceanside N/A N/A N/A 0.1Q2 A Steep Oceanside N/A N/A N/A 0.1Q2 B Fiat Oceanside 0.040 0.4300 N/A 0.1Q2 B Moderate Oceanside 0.040 0.3400 N/A 0.1Q2 B Steep Oceanside 0.040 0.2400 N/A 0,1Q2 C Flat Oceanside 0.040 0.2600 N/A 0.1Q2 C Moderate Oceanside 0.040 0.2600 N/A 0.1Q2 C Steep Oceanside 0,040 0.2000 N/A 0.1Q2 D Flat Oceanside 0.040 0.2200 N/A 0.1Q2 D Moderate Oceanside 0.040 0.2200 N/A 0.1Q2 D Steep Oceanside 0.040 0.1600 N/A 0,1Q2 A Flat L Wohlford N/A N/A N/A 0.1Q2 A Moderate L Wohlford N/A N/A N/A 0.1Q2 A Steep L Wohlford N/A N/A N/A 0.1Q2 B Flat L Wohlford 0.040 0.4300 N/A 0.1Q2 B Moderate L Wohlford 0.040 0.3800 N/A 0.1Q2 B Steep L Wohlford 0.040 0.2800 N/A 0.1Q2 C Flat L Wohlford 0.040 0.2800 N/A 0.1Q2 C Mcxderate L Wohlford 0.040 0.2800 N/A 0.1Q2 C Steep L Wohlford 0.040 0.2000 N/A 0.1Q2 D Flat L Wohlford 0,040 0.2200 N/A 0.1Q2 D Moderate L Wohlford 0.040 0.2200 N/A 0.1Q2 D Steep L Wohlford 0,040 0.1400 N/A Q2 = 2-year pre-project flow rate based upon partial duration analysis of long-term hourly rainfall records Qio = 10-year pre-project flow rate based upon partial duration analysis of long-term hourly rainfall records A = Bioretention surfac^e area sizing factor Vl = Vault volume sizing factor TABLE 4-11. Sizing Factors foi Flow-Through Planters GT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 41 X. BMP Facility IVlaintenance Requirements This section was prepared based on the Section 5 of the City of Carlsbad SUSMP. The goal is to ensure that the Owner/Developer (Shea Homes Limited Partnership) accepts responsibility for all facility maintenance, repair, and replacement to maintain, repair, and replace facilities in perpetuity and comply with the City of Carlsbad staff conducted inspection findings, self-inspection, reporting, and verification requirements. Long-term maintenance of these facilities is intended to be conducted by a Home-owners Association to be determined (HOA TBD). Proper documentation and maintenance manuals will be submitted per City of Carlsbad requirements. X.A. Description of ownership and responsibility of maintenance The City of Carlsbad will enter into a Stormwater Facilities Maintenance Encroachment Agreement with access rights and covenants (SWFMA), with Shea Homes Limited Partnership to maintain designated IMPs herein SWMP Report for this proposed residential subdivision project. The SWFMA will serve as the mechanism to ensure that proper inspection and maintenance is done in an efficient and timely manner. These IMPs are considered as private facilities which will be granted within an easement to maintain the facilities as part of the municipal storm drain system. Responsible Partv Shea Homes Limited Partnership 9990 Mesa Rim Road, Suite 200 San Diego, CA 92121 The Shea Homes Limited Partnership shall maintain the facilities fi-om the time they are constructed in perpetuity and comply with its own staff conducted inspection findings, self- inspection, reporting, and verification requirements. This can be done with hiring a management company as an agent and execution of an agreement to maintain the facilities as well as an annual inspection fee. Once a permanent Home-owner's Association is established, these responsibilities will be transferred. X.B. Summary of maintenance requirements for each stormwater facility Inspection and maintenance requirements of bioretention facility, landscaping and irrigation system, and storm drain inlet marks will be done twice a year and after each storm. Inspection can be accomplished using the inspection and maintenance tables herein. Also, at the discretion of the Project proponent, a qualified stormwater company may be hired to perform the required inspection and maintenance and provide the necessary reports. See the Tables below for facilities inspection and maintenance requirements. CT 12-01, 2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 42 Inspection and Maintenance Table BMP Type Field Measurement Inspection Frequency Maintenance Indicator Maintenance Activity Bioretention Facilitv Visual observation for sediment, trash and debris accumulation. Visual observation for vegetation health. Greater than 50% damaged vegetation. Visual observation of the drain time, standing water for more than 24 hours test with garden hose. Monitor and record the water level periodically to ensure proper drainage through the basin. Abate any potential vectors by filling holes in the ground in and around the bioretention facility and by insuring that there are no areas where water stands longer than 48 hours following a storm.( See County of San Diego Vector Control home page: http://www.sdcounty.ca.gOv/deh/pests/v ector_disease.html. Areas of bare earth are ejqjosed, mulch layer less than 3 inches. Visual observation for structural integrity: if there is any erosion, cracking, spalling, deterioration. Twice per year, prior to October 15 (rainy season), during early dry season (April), and after each major storm event (0.75 in). Sediment accumulation and debris present at the bottom of basin (specially at the inflow points) by the bypass structure. Greater than 50% damage to vegetation. Dead or diseased vegetation. Standing water for more than 24 hours. Damaged inlet/outlet structures, erosion, cracking, spalling, and deterioration. Toxic concentration of pollutants and low permeability of the soil reduced cation exchange capacity of the soil. Abate any potential vectors by filling holes in the ground in and around the bioretention facility and by insuring that there are no areas where water stands longer than 48 hours following a storm. If mosquito larvae are present and persistent, Remove accumulated sediment, trash and debris in the basin and dispose of properly by vactor truck or equal. The sediment, debris, and trash removal shall take place when the basin is dry. Dispose of trash, debris, sediment and other waste materials shall be done at suitable disposal/recycling sites and in compliance with all applicable local, state, and federal waste regulations. Remove and replace all dead and diseased vegetation, replace vegetation with vegetation with similar growth requirements, treat vegetation using preventative and low-toxic measures to the extent possible. Reestablish in accordance with the original specification. Vegetation cover shall be reestablished to the 85%. Confirm that no clogging will occur and that the basin will drain within 24 hours. Drain facility. Check over flow structure and unclog it. Check permeability of the planting soil and if it is less than 5 inch per hour then remove the top 2 to 3 inches of the soil and replace it with a fresh soil mix. CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 43 BMP Type Field Measurement Inspection Frequency Maintenance Indicator Maintenance Activity Lab test shall be done for the soil PH( PH shall be between 5.5 to 6.5), and toxic concentration (Pollutants load). Repair or replace any damaged or disconnected components. Prune and weed to maintain the bioretention area's appearance. Replenish mulch to 3 inches. Spot mulch when bare spots appear. The entire surface area of the bottom of the basin shall be remulched every 2 to 3 years. Mulch replacement shall be done prior to the start of the wet season. Generally soil may need to be replaced within 5-10 years of construction. $50.00each Annual Maintenance Cost CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 44 XI. SWMP Certification Statements XI.A. Preparer's statement The selection, sizing, and design of stormwater treatment and other control measures in this Report meet the requirements of Regional Water Quality Control Board Order R-9-2007-0001 and subsequent amendments. Ronald L. Holloway Registered Civil Engineer Date CT 12-01,2373 Plo Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 45 XI.B. Owner's statement We hereby acknowledge that this project is subject to the stormwater quality regulations ofthe City of Carlsbad and certify that this project will provide satisfactory stormwater quality measures both during the construction process and afterwards. If this project is designated as a Priority or a Standard Project, we further acknowledge our understanding that flie pennanent stormwater treatment features must remain in place, be inspected at least once annually, and be maintained in good working order. Removal or modification of these features without prior City authorization is prohibited. We certify fliat we have reviewed tiie infonnation contained in this form and voified tiiat it is both complete and correct. Owno- Signature Date 'Dwner Signature / Date Printed Name of OWUCT Pnnted Name of Owner CT12-01.2373 Pk) Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, Inc. land planning, civil engineering, suveying Page 46 I Attachments DMA/IMP sizing Exhibit Single sheet post-construction BMP Exhibit CT 12-01, 2373 Plo Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 47 DMA/IMP sizing Exhibit DMA DMA Area (sq Post- Project surface DMA Runoff DMA Area X runoff Soil Type Slope Rain Gauge Low-Flow Threshold DMA DMA Area (sq Post- Project surface DMA Runoff DMA Area X runoff Name ft) type Factor factor B Moderate Oceanside 0.1Q2 Lotl 3,400 imp 1.0 3400 Bioretention Plus Vault Lotl 8,812 Idsp 0.1 881.2 A VI V2 Lot 2 3,400 imp 1.0 3400 0.04 0.34 N/A Lot 2 10,382 idsp 0.1 1038.2 Lots 3,400 imp 1.0 3400 Lots 8,S78 Idsp 0.1 8S7.8 Lot 4 3,400 imp 1.0 3400 Lot 4 7,966 Idsp 0.1 796.6 Lots 3,400 imp 1.0 3400 Lots 6,8S0 Idsp 0.1 68S Lots 3,400 imp 1.0 3400 Lots 6,814 Idsp 0.1 681.4 Lot? 3,400 imp 1.0 3400 Lot? S,728 Idsp 0.1 572.8 ' Lots 3,400 imp 1.0 3400 ' Lots 4,547 Idsp 0.1 454.7 Street, 13,340 imp 1.0 i3340 IMP Sizing Factor, Al Proposed Area IMP Name 18 0 Idsp 0.1 0 IMP Sizing Factor, Al Min Area Proposed Area IMP Name Total 46507.7 0.04 1,860 4,279 Basin A IMP Sizing Min Proposed Factor, VI Volume Volume Total 46507.7 0.34 15,813 15,918 Basin A Volume Calculations: Basin A Depth (ft) Void Ratio Surface Area (sf) Volume (cf) Gravel Storage 3.3 0.4 4279 5648.3 Surface Storage 2.4 1.0 4279 10269.6 Total Proposed: 15917.9 (1) Proposed volume = (Proposed area * depth of gravel area * 40% void ratio) 4 (proposed area * depth of ponding layer) Proposed volume = (4,279 ft^ * 3.3 ft * 0.40) + (4,279 ft^ * 2.4 ft) = 15,918 ft^ CT 12-01,2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 48 Post- DMA DMA Project DMA Area x DMA Area (sq surface Runoff runoff Name ft) type Factor factor Lot 9 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 9 6,677 Idsp 0.1 667.7 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area LotlO 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area LotlO 6,740 Idsp 0.1 674 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lotll 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lotll 6,790 Idsp 0.1 679 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 12 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 12 5,752 Idsp 0.1 575.2 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 13 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 13 5,911 Idsp 0.1 591.1 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 14 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 14 6,171 Idsp 0.1 617.1 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 15 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 15 6,011 Idsp 0.1 601.1 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 16 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 16 4,295 Idsp 0.1 429.5 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 17 3,400 imp 1.0 3400 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Lot 17 5,174 Idsp 0.1 517.4 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Street, 18 23,518 imp 1.0 23518 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Street, 18 0 Idsp 0.1 0 IMP Sizing Proposed ,MPName Factor, Al MIn Area Area Total 59470.1 0.04 2,379 5,352 Basin B Total IMP Sizing Min Proposed Factor, VI Volume Volume 59470.1 0.34 20,220 20,338 Basin B Volume Calculations: Basin B Depth (ft) Void Ratio Surface Area (sf) Volume (cf) Gravel Storage 3.5 0.4 5352 7492.8 Surface Storage 2.4 1.0 5352 12844.8 Total Proposed: 17343.6 (2) Proposed volume = (Proposed area * depth of gravel area * 40% void ratio) + (proposed area * depth of ponding layer) Proposed volume ^ (5,352 ft^ * 3.5 ft * 0.40) + (5,352 ft^ * 2.4 ft) = 20,338 ft' I I CT 12-01,2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 49 CATCH BASIN TYPE F PER D- X=4', Y=4', V=8.33', T=e MANHOLE FRAME AND COVER PER M-2 3" ORIFICE TO ALLOW 100 YR PREDEVELOPMENT FLOW DEEP ROOTED, DENSE. DROUGHT TOLERANT PLANTING SUITABLE FOR WELL DRAINED SOiL 70' FREEBOARD TW 88.10 12" PVC OUTLET PIPE 12 PVC INLET PIPE FROM CATCH BASIN RESTRICTOR PLATE TO LIMIT FLOW FROM VI STORAGE AREA, 1.5" DRAIN DOWN HOLE 100 YR WSE ENGINEERED SOIL MIX 40" VI STORAGE LAYER, 3/4" CRUSHED ROCK 4" PERFORATED PVC UNDERDRAIN PIPE TF 78.05 PLACE PIPE WITH PERFORATIONS AT THE INVERT IMPERMEABLE BOTTOM LINER THROUGHOUT (MIRAFI 30 MIL) -ENCAPSULATE STORAGE AREA WITH MIRAFI UON OR EOUIVALENT BIORETENTION SECTION DETAIL: BASIN A NOT" ro SCALE CATCH BASIN TYPE F PER D-7 X=4', Y=4', V=8.52', 7=6" MANHOLE FRAME AND COVER PER M-2 TW 85.53 3" ORIFICE TO ALLOW 100 YR PREDEVELOPMENT FLOW 12" PVC OUTLET PIPE 12 PVC INLET PIPE FROM CATCH BASIN RESTRICTOR PLATE TO LIMIT FLOW FROM VI STORAGE AREA, 1.5" DRAIN DOWN HOLE DEEP ROOTED, DENSE, DROUGHT TOLERANT PLANTING SUITABLE FOR WELL DRAINED SOIL |— 2.?fi' FREEBOARD TW 86.87 83.20 WO YR WSE 18" ENGINEERED SOIL MIX 42" VI STORAGE LAYER, 3/4" CRUSHED ROCK 4" PERFORATED PVC UNDERDRAIN PIPE TE 77 49 PLACE PIPE WITH PERFORATIONS AT THE INVERT BIORETENTION IMPERMEABLE BOTTOM LINER THROUGHOUT (MIRAFI 30 MIL) ENCAPSULATE STORAGE AREA WITH MIRAFI MON OR EQUIVALENT SEOTION DETAIL: BASIN B wor TO SCALE CT 12-01, 2373 Pio Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 50 2 SACK CEMENT SLURRY 6" THICK ABOVE/BELOW 4" PVC STORM DRAIN PIPE RISER WALL - 3/8"xI6" STAINLESS ANCHOR BOLTS WITH WING TYPE NUTS (TYP. OF 4) RESTRICTOR PLATE BOTTOM OF BASIhf 2 SACK CEMENT SLURRY 12" BELOW TYPE 'G' BASIN AND AROUND 10" OUTFLOW PIPE .GRAVEL STORAGE LAYER PERFORATED PVC PIPE MIRAFI UON OR EOUIVALENT 30 MIL MIRAFI LINER (EACH SIDEWALL/BOTTOM) 1/4" GALVANIZE: STEEL PLATE 4" PVC PIPE- LLLLL LLLLLLC LLLLLLLLI LLLLLiJ-LLLL LlTJijgfcXLLLI ,_LLLt^Bk_LLL ?&e.LiliBEllLt£M 150" ORIFICE 3/8"xl6" STAINLESS ANCHOR BOLTS WITH WING TYPE NUTS (TYP. OF 4) NOTE- ORIFICE PLATE AND FLANGE CONNECTION TO CONCRETE SHALL BE FITTED WITH 30 DUROMETER NEOPRENE RING. STEEL PLATE TO SET ON BOTTOM OF CATCH BASIN 4" PVC PIPE FROM BASIN 1/4" GALVANIZED STEEL PLATE 50 DIA DRAIN DOWN HOLE RESTRICTOR PLATE TO LIMIT FLOW FROM STORAGE AREA RESTRICTOR PLATE DETAIL NTS CT 12-01,2373 Plo Pico Drive Project Number CDP 12-15 Priority Development Storm Water Management Plan bhA, lnc land planning, civil engineering, surveying Page 51 Single sheet post-construction BMP Exhibit Single sheet post-construction DMA Exhibit CT 12-01,2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 52 "Preliminary Geotechnical Evaluation... 2375 Pio Pico Drive, Carlsbad" dated October 2012 by GeoSoils, Inc. CT 12-01,2373 Pio Pico Drive bhA, Inc. Project Number CDP 12-15 land planning, civil engineering, surveying Priority Development Storm Water Management Plan Page 53