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CT 01-04; CALAVERA HILLS VILLAGE U; STORM WATER MGMT PLAN CALAVERA HILLS VILL U; 2003-09-16
STORM WATER MANAGEMENT PLAN for CALAVERA HILLS VILLAGE U City of Carlsbad, California Prepared for: Calavera Hills 11, LLC 2727 Hoover Avenue National City, CA 91950 w.o. 0553-0164 September 16, 2003 Amended August 3, 2004 Raymond L. Martin, R.C.E. Project Manager Hunsaker & Associates San Diego, Inc. JC:de h:\sw quality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills-Village U Storm Water Management Plan TABLE OF CONTENTS CHAPTER 1 - Executive Summary 1.1 Introduction 1.2 Summary of Pre-Developed Conditions 1.3 Summary of Proposed Development 1.4 Results and Recommendations CHAPTER 2 - storm Water Criteria 2.1 Regional Water Quality Control Board Criteria 2.2 City of Carlsbad SUSMP Criteria CHAPTER 3 - Identification of Typical Pollutants 3.1 Anticipated Pollutants from Project Site 3.2 Sediment 3.3 Nutrients 3.4 Trash & Debris 3.5 Oxygen-Demanding Substances 3.6 Oil & Grease CHAPTER 4 - Conditions of Concern 4.1 Receiving Watershed Descriptions 4.2 Pollutants of Concern in Receiving Watersheds CHAPTER 5 - Flow-Based BMPs 5.1 Design Criteria 5.2 Vortechs Treatment Units 5.3 Pollutant Removal Efficiency Table 5.4 Maintenance Requirements 5.5 Operations and Maintenance Plan 5.6 Schedule of Maintenance Activities 5.7 Annual Operations & Maintenance Costs CHAPTER 6 - Source Control BMPs 6.1 Landscaping 6.2 Urban Housekeeping 6.3 Automobile Use JC:de h;\sw quality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/04 12:52 PM Calavera Hills-Village U Storm Water Management Plan CHAPTER 7 - Site BMP Design 7.1 BMP Locations 7.2 Determination of Treatment Flows 7.3 Treatment Unit Selection CHAPTER 8 - References List of Tables and Figures Chapter 1 - Vicinity Map Chapter 1 - Watershed Map Chapter 3 - Pollutant Category Table Chapter 4 - Combined 1998 and Draft 2002 Section 303(d) Update Chapter 4 - Beneficial Uses of Inland Surface Waters Chapter 4 - Water Quality Objectives Chapter 5 - Pollutant Removal Efficiency Table (Flow-Based BMPs) Chapter 7 - Design Flow Determination Spreadsheet Chapter 7 - Low Flow Diversion Spreadsheet Chapter 7 - Vortechs Treatment Unit Capacity Table Chapter 7 - Vortechs System Data Attachments Developed Site Map JC:de li:\swqualily\0SS3\0164\swnip-03.di>c w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills-Village U Storm Water Management Plan CHAPTER 1 - EXECUTIVE SUMMARY This "Storm Water Management Pian for Calavera Hills Village U", addresses the treatment ofthe first flush runoff from the proposed development. The proposed storm drain design will utilize one stormwater treatment unit to treat the first flush flow from the proposed development. First flush design runoff calculations are provided in Chapter 7 of this report. The proposed stormwater treatment unit is a flow-based BMP (Best Management Practice) and has been specifically designed based on the runoff calculations. 1.1 - Introduction The Calavera Hills Village U, hereafter referred to as Proposed Project, proposed development is located in the City of Carlsbad, southeast of intersection of Carlsbad Village Drive and College Boulevard, as shown on the Vicinity Map below. The proposed project is bound by Carlsbad Village Drive to the north, College Boulevard to the west, steep natural hillside terrain to the east, and the proposed Village W to the south. Per the City of Carlsbad Storm Water Standards, the Calavera Hills Village U project is classified as a priority project and subject to the City's Permanent Storm Water BMP Requirements. PROJECT VICINITY MAP JC:de h:\5w qua(ity\05S3\0164\swmp-D3.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan This Storm Water Management Plan (SWMP) has been prepared pursuant to requirements set forth in the City of Carlsbad's Public works Department "Standard Urban Storm Water Mitigation Plan Storm Water Standards" (SUSMP). All calculations are consistent with criteria set forth by the Regional Water Quality Control Board's Order No. 2001-01, and the City of Carlsbad's Storm Water Standards. This SWMP recommends the location and sizing of site BMPs which include one treatment unit (see Developed Site Map for treatment unit location). Furthermore, this report determines anticipated project pollutants, pollutants of concern in the receiving watershed, peak flow mitigation, recommended source control BMPs, and methodology used forthe design of flow-based BMPs. 1.2 - Summarv of Pre-Developed Conditions The Proposed Project site drains to an unnamed tributary of the Calavera Creek, and ultimately into the Agua Hedionda Lagoon. The Regional Water Quality Control Board has identified the unnamed tributary of the Calavera Creek and Calavera Creek as part ofthe Carlsbad Hydrologic Unit (basin number 904.31) as shown in the Watershed Map on the following page. 1.3 - Summarv of Proposed Development Development of the Proposed Project will include the construction of attached multi- family condos, as well as the associated streets, sidewalks, landscaping and utilities. The "Hydrology Study for Calavera Hills Village U", prepared by Hunsaker & Associates and dated November 3, 2003, details the storm drain design for the proposed project. One flow-based BMP will be located just upstream ofthe southerly discharge location, priorto discharging into the existing storm drain system in College Boulevard. The first flush runoff from the Proposed Project site will be treated in the one proposed storm water treatment systems prior to discharging into the existing storm drain system. 1.4 - Results and Recommendations The one storm drain system has been proposed to drain the Proposed Project site. The storm drain system consists of nine (9) curb inlets, nine (9) cleanouts, and storm drain piping. This system will also incorporate a stormwater treatment system to treat the first flush runoff design flow. JC:de h:\sw quality\0553\0164\swmp-03.doc w.o. 05S3-0164 8/3/2004 12:49 PM CARLSBAD WATERSHED MAP FOR CALAVERA HILLS VILLAGE U crrr OF CARLSBAD, CALIFORNIA MBMIUMWI. III III llllltl i.iL Calavera Hills - Village U Storm Water Management Plan CHAPTER 2 - STORM WATER CRITERIA 2.1 - Regional Water Qualitv Control Board Criteria All runoff conveyed in the proposed storm drain systems will be treated in compliance with Regional Water Quality Control Board regulations and NPDES criteria prior to discharging to natural watercourses. California Regional Water Quality Control Board Order No. 2001-01, dated February 21, 2001, sets waste discharge requirements for discharges of urban runoff from municipal storm separate drainage systems draining the watersheds of San Diego County. Per the RWQCB Order, post-development runoff from a site shall not contain pollutant loads which cause or contribute to an exceedance of receiving water quality objectives or which have not been reduced to the maximum extent practicable. Post-construction Best Management Practices (BMPs), which referto specific storm water management techniques that are applied to manage construction and post-construction site runoff and minimize erosion, include source control - aimed at reducing the amount of sediment and other pollutants - and treatment controls that keep soil and other pollutants onsite once they have been loosened by storm water erosion. Post construction pollutants are a result ofthe urban development ofthe property and the effects of automobile use. Runoff from paved surfaces can contain both sediment (in the form of silt and sand) as well as a variety of pollutants transported by the sediment. Landscape activities by homeowners are an additional source of sediment. All structural BMPs shall be located to infiltrate, filter, or treat the required runoff volume or flow (based on the first flush rainfall) prior to its discharge to any receiving watercourse supporting beneficial uses. 2.2 - Citv of Carlsbad SUSMP Criteria Per the City of Carlsbad SUSMP, the Calavera Hills Village U project is classified as a Priority Project and subject to the City's Permanent Storm Water BMP Requirements. These requirements required the preparation of this Storm Water Management Plan. The Storm Water Applicability Checklist, which must be included along with Grading Plan applications, is included on the following page. JC:de ti:\sw quality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM storm Water Standards 4/03/03 VI. RESOURCES-& REFERENCES: APPENDIXA STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST Complete Sections 1 and 2 of the following checklist to determine your project's permanent and constmction storm water best management practices requirements This form must be completed and submrtted with your pemfiit application. Section 1. Permanent Storm Water BMP Requirements: If any answers to Part A are answered "Yes." your project is subject to the "Priority Project Permanent Storm Water BMP Requirements," and "Standard Permanent Storm- Water BMP Requirements" in Section III. "Permanent Storm Water BMP Selection Procedure" in the Stonn Water Standanis manual. If all answers to Part A are "No." and mi answers to Part B are "Yes." your project is only subject to the "Standard Pennanerit Storni Water BMP Requirements". If every question in Part A and B Is answered "No," your project is exempt from permanent storm water requirements. Does the project meet the definition of one or raore of the priority proiect categories?* Yea a No 1. Detached residential develooment of 10 or more units 2. Attached residential develooment of 10 or more units / 3. Commercial develooment qreater than 100,000 square feet 4. Automotive reoalr shop y 5. Restaurant '. ~~ 6. Steep hillside development greater than 5,000 square feet / 7. Proiect dischanaino to receivinq waters within Environmentallv Sensitive Areas / a. parking lots greater than or equal to 5,000 or with at least 15 parking spaces, and potentially exoosed to urban runoff / 9. Streets, roads, highways, and freeways which would create a new paved surface ttiat is 5,000 square feet or qreater Refer to the definitions section in the Storm Water Standards fbr expanded definitions of ttie proiect cateqories. i prioril ty urrrtecf Exclusion: Trenching and resurfacing work associated witii utility projects are not considered priority projects. Paridng lots, buildings and other stiljctures associated with utility pnajeds are priority projects if one or more of ttie criteria In Part A is met if all answers to Part A are "No* continue to Part B. 30 PUNMNC WT/» Huamkm Sum ENONEDUNC Sir Oi«aCJ mn suBvtm: miasmsswioo- n«iM)ss<.i4i4 BMP LOCATION MAP FOR CALAVERA VILLAGE "U' CITY OF CARLSBAD, CALIFORNIA SHEET 1 OF 1 Ki\oa27\I,Hya\oa27«Hy(a-oa-BMP-DEVSITE:HAP.0.9t Ia751flu9-03-ao04il3a8 storm Water Standards 4/03/03 Part B: Determine Standard Permanent Storm Water Requirements. Does the project propose: Yes No 1. New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks? ^^ 2. New pen/ious landscape areas and iniqation systems? 3. Penmanent stmctures within 100 feet of any natural water body? y 4. Trash storage areas? y 5. Liquid or solid material loadinq and unloading areas? 6. Vehicle or equipment fueling, washinq, or maintenance areas? 7, Require a General NPDES Pemiit for Stomn Water Discharges /Associated with Industrial Activities (Except constuction)?* / 8. Commercial or industrial waste handling or storage, excluding typical office or household waste? / 9. Anv qradinq or qround disturbance during construction? \^ 10. Any new stonn drains, or alteration to existing storm drains? 'To find out if your project is required to obtain an individual General NPDES Pemiit for Storni Water Discharges Aissociated with Industrial Activities, visit ttie State Water Resources Control Board web site at, www.swrcb.ca.gov/stomiwtr/industiial.html Section 2. Construction Storm Water BMP Requirements: If the answer to question 1 of Part C is answered "Yes," your project is subject to Section IV, "Construction Stomn Water BMP Perfonnance Standards," and must prepare a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question 1 is "No," but the answer to any of the remaining questions is "Yes," your project is subject to Section IV, "Construction Stonn Water BMP Performance Standards," and must prepare a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No," your project is exempt from any construction storm water BMP requirements. If any of the answers to the questions in Part C are "Yes," complete the construction site prioritization in Part D, below. Part C: Determine Construction Phase Storm Water Requirements Would the project meet any of these criteria during construction? Yes No 1. Is tiie project subject to Califomia's statewide General NPDES Pemiit for Stonn Water Discharqes Assodated With Construction Activities? 2. Does the project propose grading or soil disturbance? • 3. Wouid storm water or urban runoff have ttie potential to contact any portion of Uie construction area, includinq washinq and staqinq areas? 4. Wouid tiie project use any construction materials Uiat could negatively affect water quality if discharged fnam the site (such as, paints, solvents, concrete, and stucco)? / 31 I I Storm Water Standards 4/03/03 PartD: Determine Construction Site Priority In accordance with the Municipal Permit, each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low This prioritization must be completed with this fonn, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of activities necessary to complete the construction and any other extenuating circumstances that may pose a threat to water quality. The City reserves the right to adjust the priority of the projects both before and during constmction. [Note: The constmction priority does NOT change constmction BMP requirements that apply to projects; all construction BMP requirements must be identified on a case-by-case basis. The constmction priority does affect the frequency of inspections that will be conducted by City staff. See Section IV.1 for more details on construction BMP requirements.] sf A) High Priority 1) Projects where the site is 50 acres or more and grading will occur during the rainy season 2) Projects 5 acres or more. 3) Projects 5 acres or more within or directly adjacent to or discharging directly to a coastal lagoon or other receiving water within an environmentally sensitive area Projects, active or inactive, adjacent or tributary to sensitive water bodies Q B) Medium Priority 1) Capital Improvement Projects where grading occurs, however a Stonn Water Pollution Prevention Plan (SWPPP) is not required under the State General Constmction Permit (i.e., water and sewer replacement projects, intersection and street re-alignments, widening, comfort stations, etc.) 2) Pennit projects in the public right-of-way where grading occurs, such as installation of sidewalk, substantial retaining wails, curb and gutter for an entire street frontage, etc., however SWPPPs are not required. 3) Permit projects on private property where grading permits are required, however, Notice Of intents (NOIs) and SWPPPs are not required. • , C; Low Priority 1) Capital Projects where minimal to no grading occurs, such as signal light and loop installations, street light installations, etc. 2) Permit projects in the public right-of-way where minimal to no grading occurs, such as pedestrian ramps, driveway additions, small retaining walls, etc. 3) Permit projects on private property where grading permits are not required, such as small retaining walls, single-family homes, small tenant improvements, etc. 32 Calavera Hills-Village U Storm Water Management Plan CHAPTER 3 - IDENTIFICATION OF TYPICAL POLLUTANTS 3.1 - Anticipated Pollutants from Proiect Site The following table details typical anticipated and potential pollutants generated by various land use types. The Calavera Hills Village U development will consist of attached multi-family residences. Thus, the Attached Residential Development category has been highlighted to clearly illustrate which general pollutant categories are anticipated from the project area. General Pollutant Categories Priority Project Categories Sediments Nutrients Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil & Grease Bacteria & Viruses Pesticides Detached Residential Development X X X X X X X Attached Residential Development X X X p(i) p(2) P X Commercial Development >100,000 ft^ pd) pd) p(2) X p(5) X p(3) p(5) Automotive Repair Shops X X('')(5) X X Restaurants X X X X Hillside Development >5,000 ft^ X X X X X X Parking Lots pd) p(1) X X p(1) X p(1) Streets, Highways & Freeways X pd) X X(4) X p(5) X Retail Gas Outlets X X(4) X X X = anticipated P = potential (1) A potential pollutant if landscaping exists on-site. (2) A potential pollutant ifthe project includes uncovered parking areas. (3) A potential pollutant if land use involves food or animal waste products. (4) Including petroleum hydrocarbons. (5) Including solvents. JC:de ti;\sw quality\0553\0164\swmp-03.dDC w o. 0553-0164 8/3/2004 12:49 PM Caiavera Hills-Village U Storm Water Management Plan 3.2 - Sediment Soils or other surface materials eroded and then transported or deposited by the action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills, reduce spawning habitat, smother bottom dwelling organisms, and suppress aquatic vegetative growth. 3.3 - Nutrients Inorganic substances, such as nitrogen and phosphorous, that commonly exist in the form of mineral salts that are either dissolved or suspended in water. Primary sources of nutrients in urban runoff are fertilizers and eroded soils. Excessive discharge of nutrients to water bodies and streams can cause excessive aquatic algae and plant growth. Such excessive production, referred to as cultural eutrophication, may lead to excessive decay of organic matter in the water body, loss of oxygen in the water, release of toxins in sediment, and the eventual death of aquatic organisms. 3.4 - Trash & Debris Examples include paper, plastic, leaves, grass cuttings, and food waste, which may have a significant impact on the recreational value of a water body and aquatic habitat. Excess organic matter can create a high biochemical oxygen demand in a stream and thereby lower its water quality. In areas where stagnant water is present, the presence of excess organic matter can promote septic conditions resulting in the growth of undesirable organisms and the release of odorous and hazardous compounds such as hydrogen sulfide. 3.5 - Oxvgen-Demanding Substances Biodegradable organic material as well as chemicals that react with dissolved oxygen in water to form other compounds. Compounds such as ammonia and hydrogen sulfide are examples of oxygen-demanding compounds. The oxygen demand of a substance can lead to depletion of dissolved oxygen in a water body and possibly the development of septic conditions. 3.6 - Oil & Grease Characterized as high-molecular weight organic compounds. Primary sources of oil and grease are petroleum hydrocarbon products, motor products from leaking vehicles, oils, waxes, and high-molecular weight fatty acids. Elevated oil and grease content can decrease the aesthetic value of the water body, as well as the water quality. JC:de h:\swquality\0553\0164\swmp-03.doc w.o 0553-0164 8/3/2004 12:49 PM Calavera Hills-Village U Storm Water Management Plan CHAPTER 4 - CONDITIONS OF CONCERN 4.1 - Receiving Watershed Descriptions As shown in the watershed map on the following page, the pre-developed and developed condition Proposed Project site drains within the Carisbad watershed. In developed conditions, runoff from the project site drains through a proposed storm drain system that discharge near the southern project boundary into the existing storm drain system in College Boulevard. The Regional Water Quality Control Board has identified both the unnamed tributary of the unnamed tributary of Calavera Creek and Calavera Creek as part of the Carisbad Hydrologic Unit (basin number 904.31). 4.2 - Pollutants of Concern in Receiving Watersheds Neither the unnamed tributary of the Calavera Creek nor Calavera Creek are listed on the EPA's 303(d) List of endangered watenways (Table 4 included in this Chapter as evidence that Calavera Creek and the unnamed tributary are not listed). Per the "Water Quality Plan for the San Diego Basin" Table 2-2 (included at the end of this Chapter), the beneficial uses for the Agua Hedionda watenway includes municipal, agricultural and industrial service supply sources, as well as contact water recreation, non-contact recreation, warm freshwater habitat, and wildlife habitat. Table 3-2 from the "Water Quality Plan for the San Diego Basin" (also included at the end ofthis Chapter) lists water quality objectives for a variety of potential pollutants required to sustain the beneficial uses ofthe Agua Hedionda hydrologic area. JC:de h:\sw quamy\0553\0164\swmp-03.doc w.o. 0553-0ie4 8/3/2004 12:49 PM CARLSBAD WATERSHED MAP FOR CALAVERA HILLS VILLAGE U crry OF CARLSBAD. CALIFORNIA p I I I i I I I I I I I I I I I I I I Table 4 - Combined 1998'* and Draft 2002 Section 303(d) Update Hydrologic Descriptor Waterlaody Segment / Area ° Pollutant/ Stressor Extent of ImDafrment ^ Year Listed 21 Loma Aita HA (904.10) Pacific Ocean Shoreline at Loma Aita Creek Mouth Bacterial Indicators^ 1 mile 1998 22 Loma Alta HA (904.10) Loma /Mta Slough Bacterial Indicators^ Eutrophic 8 acres 1998 23 Buena Vista Greek at Buena Vista Creek Ropfartol 0.65 miles 1998 HA (904.20) Pacific Ocean Shoreline Carisbad City Beach at Carisbad Viilage Drive — DawiCi lal Indicators^ Carisbad State Beach at Pine Avenue "24 EI Salto HSA (904.21) Buena Vista Lagoon Bacterial Indicators^ Sedimentation / Siltation 350 acres 350 acres 1998 1998 Nuttients 150 acres 1998 25 Los Monos HSA (904.31) Agua Hedionda Lagoon Bacterial Indicators^ Sedimentation / Siltation 5 acres 1998 26 Los Monos HSA Agua Hedionda Creek lower portion Diazinon lower 2 miles 2002 (904.31) Agua Hedionda Creek Totai Dissolved Solids lower 8 miles 2002 27 San Marcos HA (904.50) Pacific Ocean Shoreline at Moonlight State Beach Bacterial Indicators^ 0.4 miles 1998 28 Escondido Creek Pacific Ocean Shoreline at San Elijo Lagoon tiactenal 0.8 miles 1998 HA (904.60) Pacific Ocean Shoreline at Solana Beach Indicators^ 29 San Elijo HSA (904.61) San Eiijo Lagoon Bacterial Indicators^ 150 acres 1998 Eutrophic 330 acres Sedimentation / Siltation 150 acres 30 San Dieguito HU (905.00) Pacific Ocean Shoreline at San Dieguito Lagoon Mouth Torrey Pines State Beach at Dei Mar (Anderson Canyon) -Bacterial Indicators^ 0.8 miles 1998 31 Del Dios HSA (905.21) Green Valley Creek Sulfate 1 mile 2002 32 Del Dios HSA Hodges Reservoir Entire Reservoir Color Entire 2002 (905.21) Hodges Reservoir Entire Reservoir Nitrogen Phosphoms Totai Dissolved Solids Reservoir *^ Felicita HSA (905.23) Felicita Creek Total Dissolved Solids lower 2 miles 2002 Felicita HSA (905.23) Kit Carson Creek Total Dissolved Solids 1 mile 2002 Highland HSA (905.31) Cloverdale Creek Phosphoms Total Dissolved Solids 1 mile 2002 * Sutheriand HSA _ (905.53^ Sutheriand Resen/oir Entire Reservoir Color Entire Resen/oir 2002 last updated »18/2003 S:\WQS\303dllstVSD Staff Report-2002\Za02 draft 303d list\ Table 4 • Combined 1998 and 2002 Updata.xlsVTabla 4 38 Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS 1.2 Inland Surface Waters Hydrologic Unit Basin Number M U N A G R I N D P R 0 C San Diego Coiirify Coastai Streams - continued 6 W R BENEFICIAL USE F R S H P O W R E C 1 R E C 2 B I O L W A R M C O L 0 W I L D R A R E S P W N Buena Wsfa Lagoon 4.21 See Coastal Waters- Table 2-3 Buena Vista Creek 4.22 Buena Vlsta Creek 4.21 Agua Hedionda 4.31 See Coastal Waters- Table 2-3 Agua Hedionda Creek 4.32 Buena Creek 4.32 Agua Hedionda Creek 4.31 Letterbox canyon 4.31 Canyon de las Encinas 4.40 San lUlarcos Creeic Watershed Batiquitos Lagoon 4.51 See Coastal Waters- Table 2-3 San Marcos Creek 4.52 unnamed Intemiittent streams 4.53 San lUlarcos Creeic Watershed San Marcos Creek 4.51 Encinitas Creek 4.51 * Existing Beneficial Use O Potential Berieficlal Use + Excepted From MUN (Ses Text) Waterbodies are listed multiple times if Ihey cross hydrologic area or sub area boundaries. Beneficial use designations apply to all tributaries to ttie indicated waterbody. Ifnot listed separately. Tabla 2-2 BENEFICIAL USES 2-27 March 12, 1987 Table 3-2. WATER QUALITY OBJECTIVES Concentrations not to be exceeded more than 10% of the tima during any ons one year period. Constitluent (mg/L or as noted) Ilnland Surface Waters Hydrologic Unit Basin Number TDS Cl SO 4 %Na N&P Fa Mn MBAS B ODOR Turb NTU Color Units F SAN LUIS REV HYDROLOGIC UNIT 903.00 , Lower San IOJIS HA 3.10 500 250 250 60 a 0.3 0.06 0.5 0.75 none 20 20 1.0 Monserat HA 3.20 500 250 250 60 a 0.3 0.05 0.6 0.76 none 20 20 1.0 Wamer Valley HA 3;30 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 CARLSBAD HYDROLOGIC UNIT 904.00 Loma Alta HA 4.10 none 20 20 1.0 Buena Vista Creek HA 4.20 500 260 250 60 a 0.3 0.06 O.B 0.75 nons 20 20 1.0 Agua Hedionda HA 4.30 500 260 250 60 a , 0.3 0,05 0.5 0.75 nona 20 20 1.0 Encinas HA 4.40 nons 20 20 1.0 San Marcos HA 4.50 500 250 260 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 Escondido Craek HA 4.60 500 250 250 60 a 0.3 0.05 0.5 0.75 nons 20 20 1.0 SAN DIEGUITO HYDROLOGIC UNiT 90S.00 Solana Beach HA 5.10 500 260 250 60 a 0.3 0.05 0.5 0.75 nons 20 20 1.0 Hodges HA 5.20 500 250 250 60 a 0.3 0.05 O.S 0.75 nons 20 20 1.0 San Pasqual HA 5.30 500 260 250 60 a 0.3 0.05 0.6 0.75 nons 20 20 1.0 Santa Maria Valley HA 6.40 500 250 260 60 a 0.3 0.06 0.5 0.76 nons 20 20 1.0 Santa Ysabel HA 5.50 500 260 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 PENASQUITOS HYDROLOGIC UNIT 906.00 Miramar Reservoir HA 6.10 500 250 260 60 a 0.3 0.05 0.5 0.75 nons 20 20 1.0 Poway HA 6.20 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 HA - Hydrologic Area HSA - HydroloQlc Sub Araa (Lowar case latter* indicate andnotea following the table.) Table 3-2 WATER QUAUTY OBJECTIVES Page 3-23 Septembers, 1984 Calavera Hills-Village U Storm Water Management Plan CHAPTER 5 - FLOW-BASED BMPS 5.1 - Design Criteria Flow-based BMPs shall be designed to mitigate the maximum flowrate of runoff produced from a rainfall intensity of 0.2 inch per hour. Such basins utilize either mechanical devices (such as vaults that produce vortex effects) or non-mechanical devices (based on weir hydraulics and specially designed filters) to promote settling and removal of pollutants from the runoff. Per the request of the City of Carisbad, first flush flow calculations were performed using the Rational Method. The basic Rational Method runoff procedure is as follows: Design flow (Q) = C * I * A Runoff Coefficient I - In accordance with the County of San Diego standards, the weighted runoff coefficient for all the areas draining to the treatment unit was determined using the areas analyzed in the final engineering hydrology report. The runoff coefficient is based on the following characteristics of the watershed: Land Use - Single Family Residential in Developed Areas Soil Type - Hydrologic soil group D was assumed for all areas. Group D soils have very slow infiltration rates when thoroughly wetted. Consisting chiefly of clay soils with a high swelling potential, soils with a high permanent water table, soils with clay pan or clay layer at or near the surface, and shallow soils over nearly impervious materials, Group D soils have a very slow rate of water transmission. Rainfall Intensity (I) - Regional Water Quality Control Board regulations and NPDES criteria have established that flow-based BMPs shall be designed to mitigate a rainfall intensity of 0.2 inch per hour. Watershed Area (A) - Corresponds to total area draining to treatment unit. 5.2 - Vortechs Treatment Units The Vortechs Storm Water Treatment System is designed to efficiently remove grit, contaminated sediments, metals, hydrocarbons and floating contaminants from surface runoff. Combining swiri-concentrator and flow-control technologies to eliminate turbulence within the system, the Vortechs System ensures the effective capture of sediment and oils and prevents resuspension of trapped pollutants for flows up to 25 cfs. JC:de h:\swquamy\0553\0164\svmip-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan Other features ofthe Vortechs Systems include the following: Large capacity system provides an 80 percent net annual Total Suspended Solids (TSS) removal rate Unit is installed below grade Low pump-out volume and one-point access reduce maintenance costs Design prevents oils and other floatables from escaping the system during cleanout Enhanced removal efficiencies of nutrients and heavy metals with offline configuration The tangential inlet to the system creates a swiriing motion that directs settleable solids into a pile towards the center ofthe grit chamber. Sediment is caught in the swiriing flow path and settles back onto the pile after the storm event is over. Floatable entrapment is achieved by sizing the low flow control to create a rise in the water level of the vault that is sufficient to just submerge the inlet pipe with the first flush flow. 5.3 - Pollutant Removal Efficiencv Table Pollutant of Concern BMP Categories Hydrodynamic Separation Devices*^' Vortechs'" Stormwater Treatment System Sediment M-H H Nutrients L-M L-M Heavy IVIetals L-M L-M Organic Compounds L-M L-M Trash & Debris M-H H Oxygen Demanding Substances L L Bacteria L L Oil & Grease L-H H Pesticides L L (1) The County will periodically assess the performance characteristics ofthese BMPs to update this table. (2) Proprietary Structural BMPs. Not all serve the same function. L (Low): Low removal efficiency (roughly 0-25%) M (Medium): Medium removal efficiency (roughly 25-75%) H (High): High removal efficiency (roughly 75-100%) U: Unknown removal efficiency, applicant must provide evidence supporting use Sources: Guidance Specifying Management Measures for Sources of Nonpoint Poiiution in Coastal Waters (1993), National Stonvwater Best Management Practices Database (2001), and Guide for BMP Selection in Urban Developed Areas (2001). JC:de h:\swquality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan 5.4 - Maintenance Reguirements Flow-based storm water treatment devices should be inspected periodically to assure their condition to treat anticipated runoff. Maintenance of the proposed stormwater treatment units includes inspection and maintenance 1 to 4 times per year. Maintenance ofthe Vortechs units involves the use of a "vactor truck", which clears the grit chamber ofthe treatment unit by vacuuming all the grit, oil and grease, and water from the sump. Typically a 3-man crew is required to perform the maintenance of the treatment unit. Properiy maintained Vortechs Systems will only require evacuation ofthe grit chamber portion ofthe system. In some cases, it may be necessary to pump out all chambers. In the event of cleaning other chambers, it is imperative that the grit chamber be drained first. Floatables should be removed and sumps cleaned when the sump storage exceeds 85 percent of capacity. At least once per year, the unit should be pumped down and the screen carefully inspected for damage and to ensure that it is properly fastened. Since the stormwater treatment unit is a confined space, properly trained personnel equipped with safety gear will be required to enter the unit to perform the detailed inspection. For proper maintenance to be performed, the storm water treatment facility must be accessible to both maintenance personnel and their equipment and materials. Proper inspection includes a visual observation to ascertain whether the unit is functioning properly and measuring the amount of deposition in the unit. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. Sediment removed during periodic, post-major rainfall event, and annual maintenance can be placed in a sanitary landfill or used for composting activities. If no basin maintenance takes places for a period of longer than 1 year, then trapped pollutants may be deemed hazardous and special requirements may apply to disposal activities. In such a case, removals would require testing prior to disposal in a sanitary landfill. 5.5 - Operations and Maintenance Plan The operational and maintenance needs of a Vortechs unit include: Inspection of structural integrity and screen for damage. Animal and vector control. Periodic sediment removal to optimize performance. Scheduled trash, debris and sediment removal to prevent obstruction. JC:de h:\5wqualily\0S53\0164\svmip-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills-Village U Storm Water Management Plan The facility will be inspected regulariy and inspection visits will be completely documented: Preventive maintenance activities for a flow-based treatment unit are: Trash and Debris Removal - trash and debris accumulation will be monitored during both the dry and wet season and after every large storm event (rainfall events in excess of 1 inch). Trash and debris will be removed from the Vortechs unit annually (at the end ofthe wet season). Trash and debris will also be removed when material accumulates to 85% ofthe unit's sump capacity, or when the floating debris is 12 inches deep (whichever occurs first). Sediment Removal - sediment accumulation will be monitored during both the wet and dry season, and after every large storm (1.0 inch). Sediment will be removed from the Vortechs unit annually (at the end of the wet season). Sediment will also be removed when material accumulates to 85% ofthe unit's sump capacity, or when the floating debris is 12 inches deep (whichever occurs first). Disposal of sediment will comply with applicable local, county, state or federal requirements. Corrective maintenance is required on an emergency or non-routine basis to correct problems and to restore the intended operation and safe function of a Cortechs unit. Corrective maintenance activities include: Removal of Debris and Sediment Structural Repairs - Once deemed necessary, repairs to structural components of a Vortechs unit will be completed within 30 working days. Qualified individuals (i.e., the manufacturer representatives) will conduct repairs where structural damage has occurred. 5.6 - Schedule of Maintenance Activities Target Maintenance Frequency - At a minimum, treatment unit should be cleaned annually. Maintenance Activity - Annual inspection and cleanout Clear grit chamber unit with vactor truck. Perform visual inspection Remove floatables JC:Oe h:\5w qua)ity\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan 5.7 - Annual Operations & Maintenance Costs The following costs are intended only to provide a magnitude ofthe costs involved in maintaining BMPs. Funding shall be provided by the Home Owners Association of the Calavera Hills Village U. Approximate annual maintenance costs for the proposed Vortechs unit are outlined below. Costs assume a 3 man crew: Maintenance for Vortechs model 3000: Periodic Inspection, Maintenance and Monitoring = $800 Annual Cleanout Cost = $1,000 Subtotal = $1,800 Contingency = $180 Total = $1,980 JC:de h;\sw quaiity\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills-Viliage U Storm Water Management Plan CHAPTER 6 - SOURCE CONTROL BMPS 6.1 - Landscaping Manufactured slopes shali be landscaped with suitable ground cover or installed with an erosion control system. Homeowners will be educated as to the proper routine maintenance to landscaped areas including trimming, pruning, weeding, mowing, replacement or substitution of vegetation in ornamental and required landscapes via HOA produced literature. Perthe RWQCB Order, the following landscaping activities are deemed unlawful and are thus prohibited: Discharges of sediment Discharges of pet waste Discharges of vegetative clippings Discharges of other landscaping or construction-related wastes. 6.2 - Urban Housekeeping Fertilizer applied by homeowners, in addition to organic matter such as leaves and lawn clippings, all result in nutrients in storm water runoff. Consumer use of excessive herbicide or pesticide contributes toxic chemicals to runoff. Homeowners will be educated as to the proper application of fertilizers and herbicides to lawns and gardens. The average household contains a wide variety of toxins such as oil/grease, antifreeze, paint, household cleaners and solvents. Homeowners will be educated as to the proper use, storage, and disposal of these potential storm water runoff contaminants. Per the RWQCB Order, the following housekeeping activities are deemed unlawful and are thus prohibited: Discharges of wash water from the cleaning or hosing of impervious surfaces including parking lots, streets, sidewalks, driveways, patios, plazas, and outdoor eating and drinking areas (landscape irrigation and lawn watering, as well as non-commercial washing of vehicles in residential zones, is exempt from this restriction) Discharges of pool or fountain water containing chloride, biocides, or other chemicals Discharges or runoff from material storage areas containing chemicals, fuels, grease, oil, or other hazardous materials JC:de h:\swquality\0SS3\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan - Discharges of food-related wastes (grease, food processing, trash bin wash water, etc.). 6.3 - Automobile Use Urban pollutants resulting from automobile use include oil, grease, antifreeze, hydraulic fluids, copper from brakes, and various fuels. Homeowners should be educated as to the proper use, storage, and disposal of these potential storm water contaminants. Per the RWQCB Order, the following automobile use activities are deemed unlawful and are thus prohibited: - Discharges of wash water from the hosing or cleaning of gas stations, auto repair garages, or other types of automotive service facilities. - Discharges resulting from the cleaning, repair, or maintenance of any type of equipment, machinery, or facility including motor vehicles, cement- related equipment, port-a-potty servicing, etc. - Discharges of wash water from mobile operations such as mobile automobile washing, steam cleaning, power washing, and carpet cleaning. The Homeowners Association will be responsible to make all homeowners aware of the aforementioned RWQCB regulations through a homeowners' education program. This program will consist of homeowner information literature packages provided by the HOA, inclusive of City requirements for stormwater quality concerns and informing the homeowners of their impact on the surrounding environment. JC:de h:\sw quality\0553\0164\swmp-03.doc w.o, 0553-0164 8/3/2004 12:49 PM Calavera Hills - Village U Storm Water Management Plan CHAPTER 7 - SITE BMP DESIGN VORTECHS TREATMENT UNITS 7.1 - BMP Locations The site design includes one storm water treatment unit (shown on the Developed Site Map included as an Attachment). The Vortechs treatment unit is an off-line treatment located near the southern tract boundary line, upstream of the connection with the existing storm drain system in College Boulevard. 7.2 - Determination of Design Treatment Flows The first flush design flow rates have been calculated using the Rational Method. Required input for the basin for the Rational Method treatment flow determination include the following: - Drainage Area (A) = 12.27 acres - Rainfall Intensity (I) = 0.20 inches per hour - Runoff Coefficient (C) = 0.71 The site's impervious percentage was derived based upon the total impervious area and the DU/Ac ratio, obtained by divided the total dwelling units by the total drainage area. In this case there were varying dwelling unit densities within the project site and a weighted average based on area was determined for each basin. Using the resultant dwelling units per acre ratio (DU/Ac) and the Table 3-1 from the San Diego County Hydrology Manual, the site's weighted average of impervious percentage was determined to be 43%. Based on the Rational Method calculations a peak first flush flow rate of 1.74 cfs was determined (calculations included at the end of this chapter). 7.3 -Treatment Unit Selection Per the "Vortechnics Engineered Stormwater Products" manual, dated November, 2001 (exceprts attached), the Vortechs Model 2000 has a design flow rate of 2.8 cfs. This unit (details attached), as proposed on the improvement plans, is an offline precast treatment unit, meaning that the design flow rate is forced into the treatment area through an in-line diversion structure, while flows in excess ofthe design flow proceed downstream untreated. JC:de h:\sw quality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM Calavera Hills-Village U Storm Water Management Plan Since the treatment unit is located offline there are no energy losses resulting from the treatment unit on the main storm drain line. However, the weir in the in-line diversion structure will create a restriction, which will raise the HGL upstream ofthe weir. This loss will be analyzed in the final engineering drainage study to ensure that the potential for flooding occurrences during high return rainfall events is minimized to an acceptable level. As discussed in section 7.2 the calculated first flush flow from Calavera Hills Village U was determined to be 1.74 cfs. The Vortechs Model 2000, with a peak treatment flow design capacity of 2.8 cfs, was selected because ofthe results ofthe Low Flow Diversion spreadsheet, included at the end of this chapter, show that during the 100- year storm event the diversion weir would divert 2.5 cfs through the treatment unit. Therefore the unit has been sized to handle the flow of 2.5 cfs JC:de h:\sw quality\0553\0164\swmp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM 85TH PERCEN I ILE PEAK FLOW AND VOLUME DETERMINAI IUN Modified Rational Method - Effective for Watersheds < 1.0 mi^ Hunsaker & Associates - San Diego Note: Only Enter Values In Boxes - Spreadsheet Will Calculate Remaining Values Project Name calavera Hills Village U | Work Order " 553-164 j Jurisdiction city of Carlsbad 1 BMP Location I Prior to discharge to the existing storm drain 85th Percentile Rainfall = (from County Isopluvial Map) I 0.67 I inches Developed Drainage Area = 12.3 acres Natural Drainage Area = 0.0 acres Totai Drainage Area to BMP = 12.3 acres Dev. Area Percent Impen/ious = 1 65 % Overali Percent impervious = 65 % Dev. Area Runoff Coefficient = 0.71 Nat. Area Runoff Coefficient = 0.35 Runoff Coefficient = 0.71 Time of Concentration = | 11.3 |minutes (from Drainage Study) RATIONAL METHOD RESULTS Q = CIA where V = CPA where Q = C = 1 = A = Q = C = P = A = Using tiie Total Drainage Area: C = 1 = P = A = 85th Percentile Peak Flow (cfs) Runoff Coefficient Rainfall Intensity (0.2 inch/hour per RWQCB mandate) Drainage Area (acres) 85th Percentile Runoff Volume (acre-feet) Runoff Coefficient 85th Percentile Rainfall (inches) Drainage Area (acres 0.71 0.2 inch/hour 0.67 inches 12.3 acres Q = V = 1.74 cfs 0.49 acre-feet Using Developed Area Oniy: C = 1 = P = A = Q = V = 0.71 0.2 inch/hour 0.67 inches 12.3 acres 1.74 cfs 0.49 acre-feet CALAVERA HILLS VILLAGE U HYDRAULIC ANALYSIS OF LOW FLOW DIVERSION & VORTECHS UNIT AT CLEANOUT (Node #) LOW FLOW ORIFICE (Q= I.74 cfg) Weir Formula for Orifices & Short Tubes (free & submerged) Q= Ca(2gh)''-5 (Eqn.1) Q= Ca(64.32h)"; C=0.56 Q= 4.491 a(h)''-^, where a = area of orifice opening, h = head (ft) above centeriine of orifice Orifice Size, L = 7 in., a = 0.29 sq ft. invert elevation = 100.00 ft. H= 6 in. HIGH FLOW (Q5o= 41.4 cfs) Weir Fonnula for Bypass Weir & Vortechs Weir Q = CLH^ "; C = 3.3 6.2 for Bypass for Vortechs (Eqn. 2) Bypass: L = 5.0 fL ©elevation 102.00 ft. ( 2.00 Vortechs: L = 1.0 fL ©elevation 105.00 ft. Lo Row CEq. 1) Weir Row (Eq. 2) ELEV. Orifice Vortechs Bypass TOTAL (feet) h(m Q(cfe) Hffl) Q(cfs) H(ft) Qfcfe) Q(cfe) 100.00 0.0 0.0 0.0 0.0 0.0 0.00 0.0 100.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.33 0.08 0.38 0.00 0.00 0.00 0.00 0.38 100.42 0.17 0.53 0.00 0.00 0.00 0.00 0.53 100.50 0.25 0.65 0.00 0.00 0.00 0.00 0.65 100.58 0.33 0.76 0.00 0.00 0.00 0.00 0.76 100.67 0.42 0.85 0.00 0.00 0.00 0.00 0.85 100.75 0.50 0.93 0.00 0.00 0.00 0.00 0.93 100.83 0.58 1.00 0.00 0.00 0.00 0.00 1.00 100.92 0.67 1.07 0.00 0.00 0.00 0.00 1.07 101.00 0.75 1.13 0.00 0.00 0.00 0.00 1.13 101.08 0.83 1.20 0.00 0.00 0.00 0.00 1.20 101.17 0.92 1.25 0.00 0.00 0.00 0.00 1.25 101.25 1.00 1.31 0.00 0.00 0.00 0.00 1.31 101.33 1.08 1.36 0.00 0.00 0.00 0.00 1.36 101.42 1.17 1.41 0.00 0.00 0.00 0.00 1.41 101.50 1.25 1.46 0.00 0.00 0.00 0.00 1.46 101.58 1.33 1.51 0.00 0.00 0.00 0.00 1.51 101.67 1.42 1.56 0.00 0.00 0.00 0.00 1.56 101.75 1.50 1.60 0.00 0.00 0.00 0.00 1.60 101.83 1.58 1.65 0.00 0.00 0.00 0.00 1.65 101.92 1.67 1.69 0XI0_ 0.00 goo . O.OO 1^£9 102.08 1.83 1.77 0.00 0.00 0.08 0.40 2.17 102.17 1.92 1.81 0.00 0.00 0.17 1.12 2.94 102.25 2.00 1.85 0.00 0.00 0.25 2.06 3.92 102.33 2.08 1.89 0.00 0.00 0.33 3.18 5.07 102.42 217 1.93 0.00 0.00 0.42 4.44 6.37 102.50 2.25 1.96 0.00 0.00 0.50 5.83 7.80 ft.) Lo Row (Eq. 1) Weir Row (Eq. 2) TOTAL ELEV. Orifice Vortechs Bypass TOTAL (feet) h(ft) Q(cfs) H(ft) Q(cfe) H(ft) Q(cfe) Q(cfe) 102.58 2.33 2.00 0.00 0.00 0.58 7.4 9.4 102.67 2.42 2.04 0.00 0.00 0.67 9.0 11.0 102.75 2.50 2.07 0.00 0.00 0.75 10.7 12.8 102.83 2.58 2.11 0.00 0.00 0.83 12.6 14.7 102.92 2.67 2.14 0.00 0.00 0.92 14.5 16.6 103.00 2.75 2.17 0.00 0.00 1.00 16.5 18.7 103.08 2.83 2.20 0.00 0.00 1.08 18.6 20.8 103.17 2.92 2.24 0.00 0.00 1.17 20.8 23.0 103.25 3.00 2.27 0.00 0.00 1.25 23.1 25.3 103.33 3.08 2.30 0.00 0.00 1.33 25.4 27.7 103.42 3.17 2.33 0.00 0.00 1.42 27.8 30.2 103.50 3.25 2.36 0.00 0.00 1.50 30.3 32.7 103.58 3.33 2.39 0.00 0.00 1.58 32.9 35.3 103.67 3.42 2.42 0.00 0.00 1.67 35.5 37.9 103.75 3.50 2.45 0.00 0.00 1.75 38.2 40.6 iWi aaiPii -•• ' 103.92 3.67 2.51 0.00 0.00 1.92 43.8 46.3 104.00 3.75 2.54 0.00 0.00 2.00 46.7 49.2 104.08 3.83 2.56 0.00 0.00 2.08 49.6 52.2 104.17 3.92 2.59 0.00 0.00 2.17 52.6 55.2 104.25 4.00 2.62 0.00 0.00 225 55.7 58.3 104.33 4.08 2.65 0.00 0.00 2.33 58.8 61.5 104.42 4.17 2.67 0.00 0.00 2.42 62.0 64.7 104.50 4.25 2.70 0.00 0.00 250 65.2 67.9 104.58 4.33 2.73 0.00 0.00 258 68.5 71.2 104.67 4.42 2.75 0.00 0.00 267 71.9 74.6 104.75 4.50 2.78 0.00 0.00 2.75 75.2 78.0 104.83 4.58 2.80 0.00 0.00 2.83 78.7 81.5 104.92 4.67 2.83 0.00 0.00 2.92 82.2 85.0 105.00 4.75 2.85 0.00 0.00 3.00 85.7 88.6 varteclis6lncti.xls 9/17/2003 APPROXIMATE VORTECHNICS TREATMENT AREAS ;C0MMg Model 1000 1.6 10 14 15 18 23 Model 3000 4.5 27 38 41 49 62 Model 4000 6.0 37 51 55 66 83 Model 5000 8.5 52 72 78 94 117 Model 7000 11.0 73 102 110 132 165 Model 9000 14.0 93 129 140 168 210 Model 11,000 17.5 117 162 175 210 263 Model 16,000 25.0 167 231 250 300 375 1) Iniiiol Wet Weather Phase During a b/irtHnonth storm event the water level begins, to rise above tha top of the inlet pipe. This influent cortxai featur*a reduces turbulence and avoids resuspension cf pollutants. 3) Full Capacity Phase When the highflow outlet approaches fiJ disdiarge, slnrn drains are ffciwing at peak capaciiy The VfartEchs Sy^m is designed to match vour design storm fJcw and pravide treat- ment throughout the range of storm events without bypass- ing. To acconmodate very high flow rates, Vortechnics can assist deSl'nnPrS \iMft+1 mnfimrrinm « naQl/JIi-»«< K,...^^.. 2) Transition Phase As the inflow rate increases above the controlled outflow rate, the tank fills and the floatirig contaminarl: layer accu- mulated from past storms rises. Swirling acdon increases at this stage. whOe sednnent pile remains stable. 4) Storm Subsidence Phase/Cleaning Treated runoff is decanted at a controiied rats, restoring the water level to a low dryweatiier volume and reveafing a conical pile of sediment The iow water level feciBtatBS inspection and cleaning, and signilicantiy reduces maintenance costs. The system's central baflie prevents transfer of floatables to the Stormwater Treatment Systern Parfbraed Cn«rs INV.i TVpical V Seel / Plan View Tp begin the design of your Vortechs System, refer to the sizing chart below and com- plete a Specifier's Worksheet to provide details about your site and desicfn flows. Then simply . fax or mail the worksheet to Vortechnics with your site plan, and well produce detailed Vortechs System scale draw- ings free of charge. Bevation View -Vartechs"' .;• IVIadel.;' - Erie Chsmher • . OiamEtEr/ Ares: -• -• ft/ft? ; . , Feak- Oesigrr, . Flavj^ . Sediment' Staraqa^" " Apprax: Size?' Lx W' .-- • ft Vortechs System Inlet/Outlet Configurations Vortechs Systems can be configured to accommo- date various inlet and outlet pipe orientations. The inlet pipe can enter the end or side of the tank at right angles - outlet pipes can exit the end or the side of system at most angles. End Inlet 1 Side iniet Ta Poieh Ta Pretreatment o^t^ajf SECTION 02721 STORMWATER TREATMENT SYSTEM PART 1.00 QENFRAI, 1.01 DESCRIPTION A. Wori< included: The Contactor, and/or a manufacturer selected by the Contractor and approved by the Engineer, shafl furnish all labor, materials, equipment and Incidentals required and Install all precast concrete stormwater treatment systems and appurtenances in accordance wrth the Drawings and tiiese spedfications. B. . Related woric described elsewhere: 1. Unit Masonry 2. Miscellaneous Metals 3. Waterproofing 1.02 QUALITY CONTROL INSPgCTlQN A. The quality of materials, tfie process of manufacture, and the finished sections shall be subject to inspection by the Engineer. Such Inspection may be made at tiie place of manufacture, or on the wori< site after.delivery, or at botii places, and tiie sections shall be subject to rejection at any time if material conditions fail to meet any of the spedfication requirements, even tiiough sample sections may have been accepted as satisfactory at the place of manufactured Sections rejected after delivery to the site shall be marked tor identification and shall be removed from tiie site at once.' All sections which have been damaged beyond repair during deiivery wili be rejected and. if already installed, shall be repaired to ttie Engineer's acceptance level, if permitted, or removed and replaced, entirely at tiie Conti^ctor's expense. B. All sections shall be Inspected for general appearance, dimensions, soundness, eta The surface shall be dense, dose textured and free of blisters, cracks, roughness and exposure of reinforcement C. Imperfections may be repaired, subject to the acceptance of the Engineer, after demonsti^tion by ttie manufacturer tfiat strong and permanent repairs result Repairs shall be carefully inspected before final acceptance. Cement mortar used for repairs shall have a minimum compressive strengtii of 4,000 psi at tfie end of 7 days and 5,000 psi at ttie end of 28 days when tested In 3 Inch diameter by 6 inch long cylinders stored in tiie standard manner. Epoxy morter may be utilized for repairs. 4 1.03 SUBMITTAI .9 A. Shop Drawings utifee Se^d^Snl PL?"^"^^ ^ dlmen^(S2l d'rawings and. when spedfied. details fo7mn2^S^ ^ ^^'^ for preparation of shop drawings showing Shoo drawSnc H u • ^'"^rang. joints and any cast-ln-place appurtenances. apDlicaSnH^f," to Indicate aH materials to be used and all assumnf^^nc materials, required teste of materials and design brcSH t Si**^^^ analysis. Design calculations and shop drawings shall cnnt«^«., Pf^sssional Engineer retained by ttie system manufacturer or • draw^?« i"? i^®"^®"**e state where tfie system is to be instelled; Shop cS^c -1 prepared at a scale of not less ttian 1/4" per foot Six (6) hard ^pies CT said shop drawings shall be submitted to ttie Engineer for review and approval. B; Affidavit on patent Infiingement 7^®^"^ctor shall submit to ttie Engineer, prior to Instellation oftiie stomiwater treatment system, an affidavit regarding patent Infringement righte stating tiiat • f ^^^^ against flie Owner due to alleged Infiingement righte shall be defended by ttie Contractor who will bear all tiie coste, expenses and attomey's fees incun-ed tiiereof. 1 PART 2.00 PRODlJCT.<^ 2.01 MATERIALS AND PgRlflN " A. Concrete for precast stonnwater treatment systems shall conform to ASTM C 857 and C 858 and meet tiie following addrtional requiremente: 1. The wall tiiickness shall not be less tfian 6 inches or as shown on tiie dimensional drawings. In all cases ttie wall tfiickness shall be no less tfian tfie minimum tfiickness necessary to sustain HS20-44 loading requiremente as detemnined by a Licensed Professional Engineer. 2. Sections shall have tongue and groove or ship-lap jointe with a butyl mastic sealant confonning to ASTM C 990, 3. Cement shall be Type 111 Portland cement confonning to ASTM C150. • 4. Pipe openings shall be sized to accept pipes of ttie spedfied size(s) and material(s), and shall be sealed by ttie Conttactor witfi a hydraulic cement conformiiig to ASTM C 595M 5. Intemal metel componente shall be aluminum alloy 5052-H32 in accordance witti ASTM B 209. 6. Brick or masonry used to build tfie manhole frame to grade shall confonn to ASTM C 32 or ASTM C139 and tfie Masonry Section of these Spedfications. \\MDI\SYS\DATA\V0RTECHNOIAIL\STDETAILW0RTSPEC.DGC SECTION 02721 Page 2 7. Casting for manhole frames and covers shall fae in accordance witfi The Miscellaneous Metals Section of ttiese Specifications. 8. All sections shall be cured by an approved metiiod. Sections shall not be shipped until the concrete has attained a compressive strengtii of 4,000 psi or util 5 days after fabrication and/or repair, whichever is ttie longer. 9: A biitimen sealant in confomnance witti ASTM C 990 shall be utifized In affixing ttie aluminum swiri cdiamber to the concrete vault 2.02 PERFORMANCF Each stonnwater treatinent system shall adhere to tfie following performance specifications at the spedfied design flows, as listed below: able 2.02 Vortechs Model Swirl Chamber Diameter m) Design Treatment Capacity (cfe) Sediment Storage (ytf) 1000 3.67 2.3 1.00 • 2000 4 2.8 1.25 3000 5 4.5 1.75 4000 6 6.0 2.50 5000 7 8.5 3.25 7000 8 11.0 4.00 .9000 9 14.0 4.75 11000 10 17.5 5.50 16000 12 25.0 7.00 Each stormwater treatment system shall indude a drcular aluminum 'swiri crfiamber" (or "grit chambei') with a tangential Inlet to induce a swiriing flow pattem tfiat will accumulate and store settieable solids in a manner and a location that will prevent re-suspension cf previously captjred particulates. Each swiri diamber diameter shall not be less than ttie diameter listed in Table 2.02 (neglecting diamber wall ttiickness). Each stormwater tf-eattnent system shall be of a hydraulic design ttiat Indudes flow contixjls designed and certified by a professional engineer using accepted prindples of fluid mechanics that raise the water surface inside ttie tenk to a pre-detenmined level in order to prevent the re-entrainment of ttapped floating conteminante. Each stormwater treatinent system shall be capable of removing 80% of tiie net annual Totel Suspended Solids (TSS). Individual stonnwater treatinent systems shal! have ttie Design Treatment (^padty listed in Table 102, and shall not resuspend tapped sedimente or re- enfrain floating conteminante at flow rates up to and induding tiie spedfied Design Treatment Ciapadty. Individual stonnwater tteatinent systems shall have usable sediment storage capacity of not less tiian tiie conresponding volume listed in Table 2.02. The systems shall be designed such- \\MDI\SYS\DATA\V0RTECHN\EMAIL\STDETAIL\V0RTSPECI30C SECTION 02721 Pages I I I i tiiat tiie pump-out volume is less than % of tiie totel system volume. The systems shall be designed to not allow surcharge of tiie upsti-eam piping networic during dry weatiier conditions. A water-lock feature shafl be incorporated into tfie design ofthe stonnwater tteatinent system to prevent the infroduction of ttapped ofl and floatable contaminante to Uie downstream piping during routine maintenance and to ensure tiiat no oil escapes ttie system during tiie ensuing rain event Direct access shall be provided to ttie sediment and floatable conteminant storage chambers to fadlitete maintenance. There shall be no appurtenances or restrictions within tiiese chambers. The stonnwater tteatinent system manufacturer shafl fumish documentetion which supporte all product performance claims and features, storage capacities and maintenance requiremente. Stormwater treattnent systems shall be completely housed witiiin one rectengular sfructure. * • * 2.03 MANUFACTUR FT^ Each stonnwater freattnent system shall be of a type tiiat has been Instelled and used successfully for a minimum of 5 years. The manufacturer of said system shall have been regulariy engaged In tiie engineering design and production of systems for the physical treatment of stormwater runoff. Each stonnwater treatment system shall be a Vortechs™ System as manufadured by Vortechnics, Inc., 41 Evergreen Drive, Portiand, Maine 04103, phone: 207-878-3662, fax: 207-878-8507; and as protected under U.S. Patent # 5.759.415. PART 3.00 EXECUTION- . 3.01 INSTALLATION A. Each Stonnwater Treattnent System shall be constnjcted according to tiie sizes shown on the Drawings and as spedfied herein. insteU at elevations and locations shown on ttie Drawings or as ottierwise directed by the Engineer. B. Place the precast base unit on a granular subbase of minimum tiiic:kness of six inches after compaction or of greater tfildcness and compaction if specified elsewhere. The granular subbase shall be diecked for level prior to setting and ttie precast base section of ttie trap shall be checked for level at all four comers after It is set Jf the slope from any comer to any otiier ccsmer exceeds 0.5% flie base section shall be removed and the granular subbase material re-leveled. C. Prior to setting subsequent sections place butimen sealant In conformance witfi ASTM C990-91 along tihe construction joint in ttie sedion tiiat is already in place. D. After setting tiie base and wall or riser sections instefl tiie circular swiri chamber wall by bolting the swiri diamber to tiie side walls at tiie tfiree (3) tengent points and at tiie 3-inch wide Inlet teb using HILTI brand concrete anchors or equivalent 1/2-Inch diameter by 2-3/4" minimum lengtii at heighte of approximately tfiree inches (3") off ttie fioor and at ttie mid-height of ttie completed frap (at locations of pre-drilled holes in aluminum componente). Seal tfie bottom edge of tfie swiri WMDI\SYS\DATA\V0RTECHNOMlL\STDErAlL\V0RTSPECi30C SECTICN 02721 Page 4 diamber to tiie frap floor witti tiie supplied aluminum angte flange. Adhere %" tiiick by 1" wide neoprene sponge material to tiie flange witii half of if s width on tfie horizontei leg oftiie flange and half of Ifs widtii on ttie vertical leg. The aluminum angle flange shall be affixed to ttie floor witfi a minimum 3/8* diameter by 2-3/4" drop in wedge anchor at ttie location of tiie predrilled holes. Affix tiie swiri chamber to tfie flange witfi hex head VA X 1-1/2" zinc coated self- tapping screws at tfie location of tiie predrilled holes. Seal tiie vault sidewalls to tfie outeide of tfie swiri chamber fl-om tfie floor to tfie same height as the inlet pipe invert using butyl mastic or approved equaL i i E. Prior to setting tiie precast roof section, butimen sealant equal to ASTM C990 shafl be I placed along tfie top of tiie baffle wafl, using more tfian one layer of mastic if F. necessary, to a tfiickness at least one inch (1") greater ttian ttie nominal gap between ttie top of tiie baffle ahd tiie roof section. The iiominal gap shall be detennined eittier by field measurement or ttie shop drawings. After placement of ttie raof section has compressed ttie butyl mastic sealant in tiie gap, finish sealing the gap witti an approved non-shrink grout on botti sides of ttie gap using ttie butyl mastic as a backing material to which to apply ttie grout Also apply non-shrink grout to ttie jointe at ttie side edges of ttie baflle wafl. After setting ttie precast roof section of ttie stormwater freatment system; set precast concrete manhole riser sections, to the height required to bring the cast Iron manhole covers to grade, so that tiie sections are vertical and In true alignment witii a 1/4 inch maximum tolerance allowed. Backfill in a careful manner, bringing tiie fill up In 6" lifts on afl sides. If leaks ajapear, dean tiie Inside jointe and caulk wfth lead wool to the satisfaction of tiie Engineer. Precast sections shall be set In a manner tiiat wlll result In a watertight joint In afl Instences, instellation of Stonmwater Treatinent Systems shafl conform to ASTM specification (3891 "Stendard Practice For Installation of Underground Precast Utility Stijdures". G. Plug holes In the concrete sections made for handling or other purposes with a nonshrink grout or by using grout in combination witii concrete plugs, H. Where holes must be cut in tiie precast sections to accommodate pipes, do all cutting before setting the sections in place to prevent any subsequent janing which may loosen the morter jointe. The Confractor shall make all pipe connections. b \\MDl\SYS\DATA\V0RTECH|viOIAIL\STDETAlL\V0RTSPECJD0C SECTION 02721 Page 5 VORTECHS™ STORMWATER TREATMENT SYSTEM DESIGN AND OPERATION Basic Ooeratinn The Vortechs System Is sized on ttie basis of removing botii sediment and floating poflutente from stonnwater mnoff. When ttie system is operating at ite peak design capacity, ttie maximum sen/ice rate wifl be approximately 100 gallons-per-minute per square foot of grit chambei| area (gpm/sf). The Vortechs System has been tested for flows up to and Induding tiiis maximum rate and has been shown to produce, positive removal effidendes ttiroughout tfils range. The Vortechs System will pravide a net annual removal isffidency In excess of 80% removal of Totel Suspended SoBds as tiiey are typicafly encountered In runoff from urban envlronrnente. The Vortechs System will also effectively capture and contein floatebles in stormwater runoff. The tengential Inlet creates a swiriing motion thatdlrecte settieable soRds into a pile towards ttie center of tiie grit chamber. Sediment Is caught in tiie swiriing flow patti and setfles back onto tiie pfle after tiie stonn event is over. Floatebles enfrapment Is achieved by sizing ttie low flow confrol to create a rise In tfie water level In tiie tenk that Is suffident to just submerge tfie inlet pipe in tfie 2-montti storm. The Vcjrtechs System is designed to create a backwater condition witiiin tfie system In order to maximize removal effidendes. The amount of backwater varies and is detennined by tfie Vortechnics stefl'. To prevent flooding, the final design of tiie system Incorporates afl site conditions. Desian Process During ttie Vortechs System design process consideration is given to botti tfie physical constralnte oftfie site and tiie site-spedfic flows. Each system Is designed differentiy based on these characteristics, and ttie Intemal flow confrols are specifically designed to accommodate tiie expected fiows. The site engineer provides ttie Vortechs System rim and invert elevations, pipe sizes, design flow rate, and design storm recurrence interval. Anottier consideration is whetiier the system Is In an on-line or off-line (i.e. bypassed) configuration. If regulatory authorities allow treattnent of storni flows less than ttie conveyance capadty of ttie piping system, it may be possible to provide a Vortechs Systern in an off-line configuration which wfll result in a co^ savings witiiout a significant reduction in pollutant removal effidency. Sizinq the Svstent Each system is custom designed based on the design conditions provided. The weir, orifice, sump deptti, and height of tenk wfll vary depending on ttie site conditions and performance requiremente. The rim and invert elevations wfll impact tiie overall height of the unit tiie sump deptti, and the placement of tfie weir and orifice. Also affecting tine placement of ttie weir and VORTECHS™ STORMWATER TREATMENT SYSTEM orifice is ttie pipe size, ttie onentetion of tiie intemal walls, and tiie potential for teilwater. The ^ flow rates detemnine tiie size of tiie weir, orifice, and ttie baffle opening. Size: The size of ttie system depends on whettier or not ttie system Is on-line or off-Une. An orhiine system will be chosen such ttiat ttie design flow rate is equal to or less tiien ttie Vortechs rated design flow. For an off-flne system, ttie 2-montfi flow rate is detennmed and tiie model number Is chosen based on tiie grit diamber area sudi ttiat 24 gpm/sf of flow is realized tiirough tiie chamber. Sumo: Typically a ttiree-foot sump deptii is provided in Vortechs Systems. This deptti is inost common since H provides ampte sediment storage and keeps ttie excavation depth to a minimum. However, because each Vortechs. System is custom designed, ttie individual sump depttis may vary to balance maintenance coste with capitel coste. Orifice: The fundion of tfie orifice Is to raise ttie water level In tfie Vortedis Sy^m. This Ui^ses tfie area of ttie flow In ttie pipe, whidi decreases ttie veloaty of tfie water flowing Into tiie system. A redudion in tort)ulence is realized at tiie inlet; ttiis aids in keepjng ttiejbrepped sediment and floatebles conteined. In addition, ttie rise in water level causes tiie Aoatabl^ to rise above ttie inlet and away from ttie baffle opening, ttius preventing tiie floatebles from becoming re-enfrained and pulled under tiie baffle wafl. The orifice is designed to pass a flow " approximately equal to ttiat of a 2-montti stomn event Weir, Any event greater ttian ttie 2-inontfi event causes ttie water level In the Vortedis S^ern torise to ttie upper flow conttol. submerging ttie inlet The upper flow wnfrol Is nomna^y a Clppoletti weir. A Cippoletti weir Is a ttapezoidal weir witti 4 to 1 sloping sides, l^^e the onfice ttie weir also causes ttie water level In ttie system to nse. which prornotes sediment and floatebte removal. As ttie water rises, ttie volume of water In the system '"creases, ttius stebillzing ttie detention time and allowing sediment to settle out ^he swiri is main^^^^^ allowing continuous flow ttirough ttie system via ttie weir and onflce. The weir is sized to pass ttie design flow rate minus tiie oriflce flow at fufl head. Baffle: The baffle opening is designed to maintein a veiodty sudi. ^at ^"frai^^^^^^ fl^bles and re-suspenslon of sediment is minimized "Hie baffle opening te a^ '^^'5^1!^^^ to ensure against digging. The largest opening of 15 inches is *°^e" ^ ^^^^ distence betS^een ttie floateble layer and ttie baffie opening. This keeps ^e jloatab^ tapped and maintains ttie ofl storage vdume. In most appfications. ttie flow under ttie baffle wafl is approximately 1.0 foot per second. Bypass: For systems in an off-line configuration, a weir crest ^"9* an^.f^^^^^^^^ for ttie diversion sfructure tiiat wifl be installed upsfream of tiie speafied Vortechs System. T^^ goal is to achieve a water surface elevation during ttie 100-year stomi tha^^'s at tiie^me elevation as tiie top of tiie Vortedis Clppoletti weir, lhe area of flow over the bjjass w^^^^^^^ calculated based on tiie 100-year flow. From tills area, ttie height of flow's solved for a g^^^ weir length. Since tfie area of flow remains constent ttie height of flow over ttie weir vanes witti tiie bypass weir lengtti. See Technical Bulletin 3A for more infomiaton. VORTECHS" STORMWATER TREATMENT SYSTEM Flnw Cnntrnl raloni^tinni n Vortechs Model 5000 System The Vortechs System W.Q.S. 1 is a Model 5000 witii a 7.0-fcot diameter grit chamber. In tiiis appflcation, tiie mnoff rate for a rainfafl event witti a retum firequency of 10 years is 6.13 cubic feet per second (cfs). The system design flow is 2751 gpm (6.13 cfe). The surface area of the grit chamber is 38.5 square feet, therefore ttie peak operating rate is 2751 divided by 38,5 cr 72 gpm/sf. The low flow control is a trapezoidal orifice (Qonaa). Since ttie inlet is a 24-Inch diameter pipe, the orifice must raise tiie water level 24 inches, or 2.0 feet, in a 2-montii stonn to submerge ttie inlet pipe. According to Vortechnics Technical Bulletin *3. tiie 2-montii stonn flow rate is approximately equal to tfie 10-year flow rate divided by 7. The orifice calculation based on the-full design flow is as follows: Q2^nartfi=.Q?0j«ar+7 = 6,13 * 7 = 0.88 CfS Qori»fc.= C(A)(2Sr/7)" = 0.56(0,14)(2,0 x 32.2 x 2.0)" = 0.89 cfe 4 Where C = A- Orifice conttaction coeffident = 0.56 (based on Vortechnics laboratory testing) Orifice flow area, ft^ (calculated by Vortechnics technical staff) Design head, ff (equal to tiie inlet pipe diameter) A Clppoletti weir configuration Is utilized as ttie high flow confrol (QWA) which is consen/atively designed for-tiie system design flow (Qrfea^) of 6.13 cfs. The weir calculations, are as follows: 0*^=6.13 cfe Qmir = C(L)(«)^-» = 3,37(0.50)(Z42)^-' .= 6.34 cfe 4 Where C = Cippoletti Weir coefficient = 3.37 (based on Vortechnics laboratory testing) W = Avaflable head, ft (height of weir) ^ ~ Design weir crest lengtii, ft (calculated by Vortechnics technical steff) \0 VORTECHS™ STORMWATER TREATMENT SYSTEM MAINTENANCE i *i ^"''^s minimal routine maintenance. However It Is Imoortanf that *u system be .lnspeded at reguter intervals and deaned when to eS^^^^^ Inspection Inspection is ttie key to effective maintenance and it is easiTv nerfnrmpH \/«rf«^«- recommends ongoing quarteriy Inspedions of ttie acLLlatlfLme^^^^ unusual for sediment accumulation tS be relatively OghtTSe "f * fei new Stomi drainage systems tnay be diverted to dtah ba^n sumS P^l S dPr^Si!^'*^ transport may vanr firem year to ye^ and quarteriy InspedionS Xeto li^ure^i^ S^Sh^^i^"!."* "PP^'P^*^ '"^P«^°"s should be peSd r^i^o^n h^^nter monttis In dimates where sanding operations may lead to rapid accuLtetionf o?ln ^uin^^^^^ "^aX^JS^^^"^ *° ^ *^'®^"ed when Inspedion reveate ttiat It Is neariv ftjfl- S tevel" ™rH':'''"""V'P*' "^^"'^^^^ *° Indies Ttiie d^^S Sir m!Ly^ detemiination can be made by teking 2 measuremente witii a stadia rod or i ?nn nf "3 "^^^surement Is ttie distance from ttie manhole op^Sg to tiie ^ S^L VS"S* ^'^"^ fr^'" ^« '"^"hote opening to SwaTer shSw b/ri!ln5^T M^®^^^^ measuremente Is less tfian sbc Indils tfie sySm r^l«lrf!^!^ —• ^ ^"^^ underestimating ttie volume of sediment In ttie diSnber ritiS2TS?o^''5*T'^^?^'°'''^^*°*^*°P°^*^^ RneTs% Sav^lSt'^rJf^f where ttie risk of large pefroleum spifls Is small, liquid conteminante dSneS o!?^^^ •^f """iS^ ^ ^^"^^""^ ^ °» Sasofine spill should be i immediately. Oil or gas ttiat accumulates on a more routine basis should be • removed when an appredable layer has been captured. Cteaning S^pnlf n?L*»! ^""^ ^ ^^"^ 9®"e^'y the most effedive and SS!!? ^eanout should not occur wittiin 6 hours of a rain event te allow ttie entire "^"^^ P'^Pefiy maintained Vortedis Systems will only require nl!«f* ? •? *® P°^°" "^^ *® ^em. in which case only the manbote cover nearest to the system inlet need be opened to remove water and conteminante. Hcwever, all -nf^e^^P : u ^ ^^^'^ *° *® '"*®9^ ^ the system. In Instellations where a aamsneii is being utilized for sdids removal, prior to removing the grit, absoriDent pads or pillows can be placed in tiie ofl chamber to remove floating contaminante. Once tills is done, | sediment may ttien be easily removed witfi tfie damshell. ^ VORTECHS™ STORMWATER TREATMENT SYSTEM In some cases, it may be necessary to pump out all chambers. An Important maintenance i"^° Systems is tfiat floatebles remain frapped after a cSnT A pocSS of water between tfie grit diamber and tfie outiet panel keeps tfie bottom of "tiie b^e ?llp^nl • '2,^^* ^" *^PP®^ ^tem begins to fifl up ag Jn dSS• r °^ °'^^"'"S it's imperative tfiat tiie grit diamber be arawied first Manhde covers should be securely seated following cleaning activities, to ensure ttiat surface mnoff does not leak Into ttie unit from above. •V: Calavera Hills - Village U Storm Water Management Plan CHAPTER 8 - REFERENCES "Standard Urban Storm Water Mitigation Plan - Storm Water Standards", City of Carlsbad, April 2003. "San Diego Municipal Code Land Development Manual Storm Water Standards", City of San Diego, California; May 2003. "Hydrology Study for Calavera Hills - Village U", Hunsaker & Associates San Diego, Inc.; November 3, 2003. "San Diego County Hydrology Manual", County of San Diego Department of Public Works - Flood Control Section; June 2003. "Order No. 2001-01, NPDES No. CAS0108758 - Waste Discharge Requirements for Discharges of Urban Runoff from the Municipal Separate Storm Sewer Systems (MS4s) Draining the Watersheds ofthe County of San Diego, the Incorporated Cities of San Diego County, and San Diego Unified Port District", California Regional Water Quality Control Board - San Diego Region; February 21, 2001. "Water Quality Plan forthe San Diego Basin", California Regional Water Quality Control Board - San Diego Region, September 8, 1994. "Vortechnics Storm Water Pollution Control Technical IVIanual", Vortechnics Technologies, Updated November 2001. JC:de li;\sw quality\0553\0164\swinp-03.doc w.o. 0553-0164 8/3/2004 12:49 PM