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Home My WebLink AboutCT 02-23; VILLAGE OF LA COSTA GREENS NGHBD 1.08; STORM WATER MANAGEMENT PLAN; 2004-06-03I I I I I I I I I I I I I I I I :1 I. I PLANNING ENGINEERING SURVEYING IRVINE LOS ANGELES RIVERSIDE SAN DIEGO DAVE HAMMAR LEX WILLIMAN ALiSA VIALPANDO DAN SMITH RAY MARTIN 10179 Huennekens St. San Diego, CA 92121 (858) 558-4500 PH (858) 558-1414 FX www.Hunsaker5D.com Info@HunsakerSD.com HUNSAKER &ASSOCIATES 5 AND lEG 0, INC. STORM WATER MANAGEMENT PLAN . for LA COSTA GREENS NEIGHBORHOOD 1.08 City of Carlsbad, California Prepared for: Real Estate Collateral Management Company c/o Morrow Development 1903 Wright Place, Suite 180 Carlsbad, CA 92008 W.o. 0107-260 June 3,2004 Eric MO~'1f:ic Water Resources Department Manager Hunsaker & Associates San Diego, Inc. RECEIVED AUG 1 2 2004 ENGINEERING DEPARTMENT CTf.)2 ('~3 h'l< efF9 KT:kc H:IREPORTSI0107l2601SWMP01.doc w.o. 0107-260 614/2004 10:57 AM I I I I I I I I I I I I I I I I I I ,I La Costa Greens Neighborhood 1.08 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 1.5 Conclusion CHAPTER 2 -Storm Water Criteria 2.1 Regional Water Quality Control Board Criteria 2.2 City of Carlsbad SUSMP Criteria CHAPTER 3 -Identification of Typi.cal 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 3.7 Bacteria & Viruses 3.8 Pesticides 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 Schedule of Maintenance Activities 5.6 Annual Operations & Maintenance Costs KT: H:IREPORTSI23521057\SWMP01.doc w.o. 2352-67 6131<004 3:40 PM r-------------------------------------------------------------------------~-, I I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 6 -Source Control BMPs 6.1 Landscaping 6.2 Urban Housekeeping 6.3 Automobile Use 6.4 Site Design BMPs CHAPTER 7 -Site BMP Design (Vortechs Treatment Units) 7.1 BMP Locations 7.2 Determination of Treatment Flows 7.3 Vortechs Treatment Unit Selections CHAPTER 8 -References List of Tables and Figures Chapter 1 -Watershed Map Chapter 3 -Pollutant Category Table Chapter 4 -San Diego Region Hydrologic Divisions 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 6 -Pollutant Removal Efficiency Table (Flow-Based BMPs) Chapter 7 -85th Percentile Rainfall Isopluvial Map Chapter 7 -Neighborhood 1.08 BMP Location Map Chapter 7 -Design Runoff Determination Summary Table Chapter 7 -Vortechs Unit Treatment Capacity Table Chapter 7 -Vortechs System Data Attachments BMP Location Map KT:de H:IREPORTS\23521067ISWMP01.doc w.o. 2352-67 6/3/2004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 1 -EXECUTIVE SUMMARY 1.1 -Introduction Phase 1 of the La Costa Greens project site is located north of Alga Road, south of the proposed extension of Poinsettia Lane, and east of the La Costa Golf Course. Neighborhood 1.08 is located in the north of the development, bisected by Alicante Road, east of the golf course, north of Neighborhood 1.09 and south of Poinsettia Road. Neighborhood 1.08 is one of seven subdivisions within the La Costa Greens Phase I development. An exhibit showing the location of each treatment unit and the breakdown of the areas tributary to each treatment unit is included on the following page. All runoff from Neighborhood 1.08 will drain to a proposed storm drain outlet located adjacent to Alicante Road on the east side just no-rth of Neighborhood 1.08. In addition to the flow contributed by Neighborhood 1.08, a portion of Alicante Road and developed offsite areas to the east (totaling 14 acres) will also drain to the Alicante Road outlet. Runoff ultimately drains to an unnamed tributary of San Marcos Creek. Flow from this tributary eventually discharges into San Marcos Creek towards the Batiquitos Lagoon. Per the City of Carlsbad SUSMP, the La Costa Greens Neighborhoods 1.08 project is classified as a Priority Project and subject to the City's Permanent Storm Water BMP Requirements. VICINITY MAP NTS KT:de H:IREPORTSI235210671SWMP01.doc w.o. 2352-67 6/312004 3:40 PM I I I I I I I I I I .~ I I I I I I II I · LEGEND LA COSTA GREENS WATERSHED TRIBUTARY POST-CONSTRUCTION TO TREATMENT UNIT --~---BMP LOCATION EXHIBIT WATERSHED TRIBUTARY ~ TO TREATMENT UNIT . \ ~ / FLOW·BASED BMP FOR "7.011 .......... NEIGHBORHOOD 1.08 AND ALICANTE ROAD FLOW·BASED BMP FOR -__ NEIGHBORHOOD 1.09, 1.10, AND PORTION OF 1.12 FLOW·BASED BMP FOR NEIGHBORHOOD 1.11 FLOW·BASED BMP FOR -~~~"'~l?< NEIGHBORHOOD 1.13,1.14, PORTION OF 1.12, AND AUCANTE ROAD R'\0326\&Hycl\Slte Loc:o.tlon Mo.p a.Sxll.clwg( 127SJJun-10-2003'lS,21 IL---------------------------~ __ ~ I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan This Storm Water Management Plan (SWMP) has been prepared pursuant to requirements set forth in the City of Carlsbad's "Standard Urban Storm Water Mitigation Plan (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 SUSMP. This SWMP recommends the location and sizing of site Best Management Practices (BMPs) which include a single Vortechs treatment unit (see BMP Location Map in this chapter). Furthermore, this report determines anticipated project pollutants, pollutants of concern in the receiving watershed, peak flow mitigation, recommended source control BMPs, and methodology used for the design of flow-based and volume- based BMPs. 1.2 -Summary of Pre-Developed Conditions - Phase 1 of the La Costa Greens project site is located north of Alga Road, south of the proposed extension of Poinsettia Lane, and east of the La Costa Golf Course. Neighborhood 1.08 is located in the north of the development, bisected by Alicante Road, east of the golf course, north of Neighborhood 1.09 and south of Poinsettia Road. Runoff from the site in natural conditions drains to the San Marcos Creek. The Regional Water Quality Control Board has identified San Marcos Creek as part of the Carlsbad Hydrologic Unit, San Marcos Hydrologic Area, and the Batiquitos Hydrologic Subarea (basin number 4.51). 1.3 -Summary of Proposed Development The La Costa greens Neighborhood 1.08 project will include construction of five (5) proposed roads, grading of the proposed site to make it suitable for construction of single-family residential dwellings, construction of underground utilities typically associated with residential developments, and the construction of 82 residences. The proposed project site consists of 82 residential lots and 6 open space lots, for a total area of 36.43 acres (22.44 acres and 13.99 acres respectively). Approximately 38% of the Neighborhood 1.08 proposed project site will remain undeveloped. The offsite developed areas, which will drain through Neighborhood 1.08 have been quantified in two hydrology studies; "Hydrology & Hydraulic Study -La Costa Greens Phase 1", prepared by O'Day ConSUltants May 25,2002, and "Tentative Map Drainage Study for La Costa Greens -Phase1 Neighborhoods 1.08 through 1.14," prepared by Hunsaker & Associates San Diego, Inc. April 17, 2003. The O'Day report identified a total of 14 acres of offsite developed area that contribute flow to the La Costa development in the vicinity of the Neighborhood 1.08. The Hunsaker & Associates report identified one run on location at the northeast corner Kl":de H:IREPORTS1235210S1\SWMP01.doc w.o.2352067 613/20043:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan of Neighborhood 1.08 consisting of 14 acres of area. The Quadrangle Map Watershed Exhibit for La Costa Greens illustrates the approximate extent of offsite areas draining to the La Costa Greens Phase I proposed development and has been included in the Attachment section of this report. Development of the site will not cause any diversion to or from the existing watershed to the storm drain system. . The proposed treatment unit will located offline from the main storm drain system and is proposed in the vicinity of Alicante Road north of Street "K" (see Ultimate Condition Site Map included in the pocket of the this report). 85th percentile runoff will be treated in a storm water BMP prior to discharge to the existing storm drain and detention basin. Flows in excess of the treatment flow will bypass the treatment unit. A runoff coefficient of 0.63 was assumed for the proposed single-family residential development, based on City of Carlsbad criteria. 1.4 -Results and Recommendations Using the 85th percentile rainfall of 0.67 inches (see Isopluvial Map in chapter 7) and assuming approximately 25 percent imperviousness in the contributing watershed Table 1 below summarizes rational method 85th percentile calculations for the proposed water quality treatment unit for the La Costa Greens Neighborhood 1.08 development. Table 1 -Developed Conditions 85th Percentile Calculations Drainage S5tn Rainfa" Percent Percentile Runoff Area Area Rainfall Intensity Coefficient Impervious (acres) (inches) (inches/hour) (%) West Storm 61.4 0.67 0.2 0.63 50 Drain Unit *Note: Includes area from Bressl developments Rational Method calculations predicted an 85th percentile runoff flow of roughly 7.7cfs for the area discharging to the storm drain. 85th percentile flows will be treated in the proposed Vortechs unit prior to discharging to the Alicante Road storm drain. The proposed Vortechs unit is an offline precast treatment unit. The 85th percentile design flow rate is forced into the treatment area by a diversion weir built in the upstream junction. Flows in excess of the design flow rate pass over the weir and proceed downstream. KT:de H:\REPORTS\23521067ISWMP01.doc w.o. 2352-67 613/2004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan A single Vortech Model 9000 unit (or approved equivalent unit) with a treatment flow capacity of 7.7 cfs is recommended for the unit located upstream of the receiving storm drain. 1.5 -Conclusion The combination of proposed construction and permanent BMP's will reduce, to the maximum extent practicable, the expected project pollutants and will not adversely impact the beneficial uses of the receiving waters. KT:de H:\REPORTS\23521067\SWMP01.doc w.o. 2352·67 613/20043:40 PM I I I I I I I I I I I I I I I II I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 2 -STORM WATER CRITERIA 2.1 -Regional Water Quality 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 receivihg water quality objectives or which have not been reduced to the maximum extent practicable. Post-construction Best Management_Practices (BMPs), which refer to 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 of the urban development of the 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 85th percentile rainfall) prior to its discharge to any receiving watercourse supporting beneficial uses. 2.2 -City of Carlsbad SUSMP Criteria Per the City of Carlsbad SUSMP, the La Costa Greens Neighborhood 1.08 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. KT:de H:\REPORTS\235210671SWMP01.doc w.o. 2352·67 613/2004 3:40 PM I I I I I I I I I I I I I I :1 I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 3 -IDENTIFICATION OF TYPICAL POLLUTANTS 3.1 -Anticipated Pollutants from Project Site The following table details typical anticipated and potential pollutants generated by various land use types. The La Costa Greens Neighborhoods 1.08 development will consist of detached single-family residence. Thus, the Detached Residential Development categories have been highlighted to clearly illustrate which general pollutant categories are anticipated from the project area. Priority Project Categories Commercial x x Development p(1) p(1) >100 000 fe Automotive Repair Restaurants H Development X X >5000 fe Parking Lots p(1) p(1) Streets, Highways & X p(1) Retail Gas Outlets X = anticipated p = potential x p(2) X X X(4)(5) X X X X X x x X x (1) A potential pollutant if landscaping exists on-site. p(1) p(2) p X X X X X X X p(1) x p(5) x x (2) A potential pollutant if the 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. x p(5) X p(1) KT:de H:IREPORTS123521061\SWMP01.doc w.o. 2352·67 6/312004 3:40 PM I I I I I I I I I I I I I I I i'l I I I La Costa Greens Neighborhood 1.08 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 -Oxygen-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 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. KT:de H:IREPORTS123521067ISWMP01.doc w.o. 2352·67 6/3/2004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan 3.7 -Bacteria & Viruses Bacteria and viruses are ubiquitous microorganisms that thrive under certain environmental conditions. Their proliferation is typically caused by the transport of animal or human fecal wastes from the watershed. Water, containing excessive bacteria and viruses can alter the aquatic habitat and create a harmful environment for humans and aquatic life. Also, the decomposition of excess organic waste causes increased growth of undesirable organisms in the water. 3.8 -Pesticides Pesticides (including herbicides) are chemical compounds commonly used to control nuisance growth or prevalence of organisms. Excessive application of a pesticide may result in runoff containing toxic levels of its active component. KT:de H:IREPORTS\235210671SWMP01.doc w.o.2352·67 613/20043:40 PM I I I I I I I I I I I I I I· I I I :1 I La Costa Greens Neighborhood 1.08 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 La Costa Greens Neighborhoods 1.08 site drains to an unnamed tributary of San Marcos Creek which eventually discharges to the Batiquitos Lagoon within the San Marcos Creek watershed. Development of the site will not cause any diversion to or from the existing watershed to the storm drain system. The Regional Water Quality Control Board has identified San Marcos Creek as part of the Carlsbad Hydrologic Unit, San Marcos Creek Watershed, and the Batiquitos Hydrologic Subarea (basin number 4.51). 4.2 -Pollutants of Concern in Receiving Watersheds San Marcos Creek is not listed on the EPA's 303(d) List of endangered waterways (included in this Chapter). Per the "Water Quality Plan for the San Diego Basin", the beneficial uses for the Batiquitos Lagoon and San Marcos Creek includes agricultural supply, 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" (included at the end of this Chapter) lists water quality objectives for a variety of potential pollutants required to sustain the beneficial uses of the San Marcos hydrologic area. KT:de H:IREPORTSI2352\0871SWMP01.doc w.o.2352·67 613120043:40 PM -- - . ..,.~~ , ~ , 1 ;'" , . .. .. ~ ~ -' . . 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":.: ',I ... ~" ~ - - ------ -- -----=~-" '--- LA COSTA GREENS NEIGHBORHOOD 1.08 CITY OF CARLSBAD, CAUFORNIA - 1 I I 26 Los Monos HSA Agua Hedionda Bacterial (904.31) Lagoon IndicatorsE 6.8 acres 1998 I Sedimentation I Siltation 27 Los Monos HSA (904.31) Agua Hedionda I rt' Total Dissolved lower 7 miles 2002 C k ower po Ion Solids I ree 28 San Marcos HA Pacific Ocean at Moonlight State Beach Bacterial 0.4 miles (904.S0) Shoreline IndicatorsE 1998 I 29 Escondido Creek Pacific Ocean at San Elijo Lagoon Bacterial 0.44 miles HA (904.60) Shoreline IndicatorsE 1998 30 San Elijo HSA San Elijo Bacterial 150 acres I (904.61) Lagoon IndicatorsE 1998 Eutro~hic 330 acres Sedimentation I 1S0 I Siltation acres 31 San Dieguito HU Pacific Ocean at San Dieguito Lagoon Mouth Bacterial 0.86 miles (90S.00) Shoreline IndicatorsE 1998 I 32 Del Dios HSA Green Valley (905.21 and Sulfate 1 mile 2002 905.22) Creek 33 Del Dios HSA Hodges Entire Reservoir Color Entire 2002 I (905.21) Reservoir Nitrogen Reservoir Phosehorus (1104 acres) Total Dissolved I Solids 34 Felicita HSA (90S.23) Felicita Creek Total Dissolved lower 0.92 2002 I Solids miles 35 Felicita HSA Kit Carson Total Dissolved (905.23) Creek should in 905.21 HSA Solids 1 mile 2002 I 36 Highland HSA Phosphorus 1.2 miles 2002 (90S.32) Cloverdale Total Dissolved Creek 'I Solids 37 Sutherland HSA Sutherland Entire Reservoir Color Entire 2002 (905.S3) Reservoir Reservoir I 38 Miramar Reservoir Los Sedimentation I 469 HA (906.10) Penasquitos Entire Lagoon Siltation acres 1998 Laaoon I 39 Miramar Reservoir Pacific Ocean Torrey Pines State Beach at Del Bacterial 0.4 miles 2002 HA (906.10) Shoreline Mar (Anderson Canyon) IndicatorsE 40 Scripps HA La Jolla Shores Beach at EI Paseo 3.9 miles 1998 (906.30) Pacific Ocean Grande Bacterial I Shoreline La Jolla Shores Beach at Cam in ito IndicatorsE Del Oro La Jolla Shores Beach at I Vallecitos La Jolla Shores Beach at Ave de la Playa I last updated 9/23/2003 S:\WQS\303dlist\SD Staff Report-2002\FINAL VERSIONS\Listed Waterbodies-2002.xls\Table 4 (Sep03 page 3 of6 I Table 2-2. BENEFICIAL USES O,F INLAND SURFACE WATERS BENEFICIAL USE 1,2 M A I P G F P R R B W C W Inland Surface Waters Hydrologic Unit U G N R W 'R 0 E E I A 0 I Basin Number N R D 0 R S W C C '0 R L L C H 1 2 L M D D San'Diego County Coastal Streams -continued Buena Vista Lagoon 4.21 See Coastal Waters-Table 2-3 Buena Vista Creek 4.22 + • • • • • • Buena Vista 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 + 0 • • • San Marcos Creek Watershed Batiquitos Lagoon 4.51 See Coastal Waters-Table 2-3 San Marcos Creek 4.52 + • • • • • unnamed Intermittent streams 4.53 + • • • • • San Marcos Creek Watershed San Marcos Creek 4.51 + • • • • • Encinitas Creek 4.51 + • • • • • 1 Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries. • Existing Beneficial Use o Potential Beneficial Use 2 Beneficial use designations apply to all tributaries to the indicated waterbody, if not listed separately. + Excepted From MUN (See Text) Table 2-2 BENEFICIAL USES 2-27 R S A P R W E N • March 12, 1997 ------------------- Table 2-3. BENEFICIAL USES OF COAS·TAL WATERS --~-------------~ --- BENEFICIAL USE Coastal Waters Hydrologic I N R R C B E W Unit Basin N A E E .0 I S I Number 0 V C ·C M 0 T L 1 2 M L 0 Pacific Ocean • • • • • • • Dana Point Harbor • • •• • • • Del Mar Boat Basin • • • • • • Mission Bay I • • • • • • Oceanside Harbor • • • • • • San Diego Bay 1 • • • • • • • • Coastal Lagoons .-11. ; 1 • Tijuana River Estuary • • • • • Mouth of San Diego River 7.11 • • • • • Los Penasquitos Lagoon 2 6.10 • • • • • San Dieguito Lagoon 5.11 • • • • • Batiquitos. Lagoon 4.51 • • • • • San Elijo Lagoon . 5.61 • • • • • Aqua· Hedionda .Lagoon 4.31 • • • • • • Includes the tidal prisms of the Otay and Sweetwater Rivers. 2 Fishing from shore or boat permitted, but other water contact recre~tional (REC-1) uses are prohibited. • Existing Beneficial Use Table 2-3 BENEFICIAL USES 2-47 R A R E • • • • • • • • .. • • • • M A M S Wi S II A Q I P A H R. U G W R E A R N M L L • • • •• • • • • • • • • • • • •• • • • • • • • • • • .-• • • • • • • • • • • • • • • • • • • • • • • • • March 12, 1997 ------------------- ·' ."' .... /' Table 3-3. WATER QUALITY OBJECTIVES Concentrations not to be exceeded more than 10% of the time during anyone year period Constituent (mg/L or as noted) Ground Water Hydrologic Turb Color Basin Unit TOS CI S04 %Na NOs Fe Mn MBAS 8 ODOR NTU Units F Number Buena Vista Creek HA 4.20 EI Saito HSA a 4.21 3500 BOO 500 60 45 0.3 0.05 0.5 2.0 none 5 15 1.0 I 1000 b 400 b· 500 b Vista HSA a 4.22 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 5 15 1.0 Agua Hedionda HA a 4.30 1200 500 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Los Monos HSA aj 4.31 3500 800 500 60 45 0.3 0.05 0.6 2.0 none 5 15 1.0 Encinas' HA a 4.40 3500 b 800 b 500 b 60 45 b 0.3 b 0.05 b . 0.5 2.0 b none 5 15 1.0 San Marcos HA ae 4.60 1000 400 600 60 10 0.3 0.05 0.5 0.76 none 5 15 1.0 Batiquitos HSA aek .14..51 3500 800 500 60 45 0.3 0.05 0.5 2.0 none 5 15 1.0 Escondido Creek HA a 4.60 750 300 300 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 San Elijo HSA a 4.61 2800 700 600 60 45 0.3 0.05 0.5 1.0 none 5 15 1.0 Escondido HSA 4.62 1000 300 400 60 10 0.3 0.05. 0.5 0.75 none 5 15 1.0 SAN OIEGUITO HYDROLOGIC UNIT 905.00 Solana Beach .. HA a 5.10 1500 b 500 b 500 b 60 45 b 0.85 b 0.15 b 0.5 0.75 b none 5 15 1.0 Hodges HA 5.20 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 5 15 q~' San Pasqual HA 5.30 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 5 15 1.0 Santa Maria Valley HA 5.40 1000 400 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Santa Ysabel HA 5.50 500 250 250 60 5 0.3 0.05 0.5 0.75 none 5 15 1.0 PENASQUITOS HYDROLOGIC UNIT 906.00 Miramar Reservoir HA af 6.10 1200 500 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Poway HA 6.20 760 q 300 300 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Scripps HA 6.30 -- - - ------- -- Miramar HA 9 6.40 750 300 300 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Tecolote HA 6.50 -------------.. _. ~. ...... --.... ---.... ~--_ ... HA ' Hydrologic Area HSA -Hydrologic Sub Area (lower case letters indicata endnotes following the table.1 Table 3-3 WATER QUALITY OBJECTIVES Page 3-29 October 13, 1994 - - ---- - ------------ I I I I I I I I I I I I I I I I I II I La Costa Greens Neighborhood 1.08 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 Carlsbad, 85th percentile 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 (C) -In accordance with the City of Carlsbad 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 swirl-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. KT:de H:IREPORTS\23521067ISWMP01.doc w.o. 2352·67 613/2004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan Other features of the 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 swirling motion that directs settleable solids into a pile towards the center of the grit chamber. Sediment is caught in the swirling flow path and settles back onto the pile atter 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 85th percentile flow. 5.3 -Pollutant Removal Efficiency Table Pollutant of Concern BMP Categories Hydrodynamic Separation Devices(2) (1) The County will periodically assess the performance characteristics of these 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 Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database (2001), and Guide for BMP Selection in Urban Areas KT:de H:\REPORTSI23521067ISWMP01.doc w.o. 2352·67 6/3/2004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan 5.4 -Maintenance Requirements Flow-based storm water treatment devices should be inspected periodically to assure their condition to treat anticipated runoff. Maintenance of the proposed Vortechnics units includes inspection and maintenance 1 to 4 times per year. Maintenance of the Vortechs units involves the use of a "vactor truck", which clears the grit chamber of the 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. Properly maintained Vortechs Systems will only require evacuation of the grit chamber portion of the 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. Proper inspection includes a visual observation to ascertain whether the unit is functioning properly and measuring the amount of deposition in the unit. Floatables should be removed and sumps cleaned when the sump storage exceeds 85 percent of capacity specifically, or when the sediment depth has accumulated within 6 inches of the dry-weather water level. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. 5.5 -Schedule of Maintenance Activities Target Maintenance Date -March 15th Maintenance Activity -Annual inspection and cleanout. Clear grit chamber of each unit with vactor truck. Perform visual inspection. Remove floatables. 5.6 -Annual Operations & Maintenance Costs The following costs are intended only to provide a magnitude of the costs involved in maintaining BMPs. Funding shall be provided by the Master Home Owners Association for La Costa Greens, of which neighborhood 1.08 is a member of. Approximate annual maintenance costs for each ofthe·proposed Vortechs units are outlined below. Costs assume a 3 man crew: Maintenance for Model 9000: Periodic Inspection, Maintenance and Monitoring = $800 Annual Cleanout Cost = $2,000 Subtotal = $2,800 Contingency = $280 Total = $3,080 KT:de H:IREPORTS123521067\SWMP01,doc w.o.2352·67 613120043:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 6 -SOURCE CONTROL BMPS 6.1 -Landscaping Manufactured slopes shall be landscaped with suitable ground cover or installed with an erosion control system. Homeowners should 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. Per the 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 should 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 should 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 irr.igation 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 Discharges of food-related wastes (grease, food processing, trash bin wash water, etc.). KT:de H:IREPORTS1235210671SWMP01.dac w.o. 2352-67 6/312004 3:40 PM I I I I I I -I I I I I I -I -I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan 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 should make all homeowners aware of the aforementioned RWQCB regulations through a homeowners' education program. A monitoring program should also be implemented to insure compliance. 6.4 -Site Design BMPs Priority projects, such as the La Costa Greens Neighborhood 1.08 development, shall be designed to minimize, to the maximum extent practicable the introduction of pollutants and conditions of concern that may result in significant impact, generated from site runoff to the storm water conveyance system. Site design components can significantly reduce the impact of a project on the environment. The following design techniques have been proposed to accomplish this goal. Implementing on-lot hydrologically functional landscape design and management practices; Additional detail regarding landscaping design is discussed in section 6.1. Minimizing project's impervious footprint. Methods of accomplishing this goal include constructing streets, sidewalks, and parking lots to the minimum widths necessary without compromising public safety. Another method for minimizing impervious area includes incorporating landscaped areas in the drainage system to encourage infiltration and reduce the amount of directly connected impervious areas. -Minimizing directly connected Impervious Areas. Where landscaping is proposed, drain rooftops into adjacent landscaping prior to discharging to the storm water conveyance system. KT:de H:IREPORTSI235210671SWMP01.doc w.o. 2352·67 61312004 3:40 PM I I ,I I I I I I I I I I I .1 I I ,I i II I La Costa Greens Neighborhood 1.08 Storm Water Management Plan Approximately 38% of the Neighborhood 1.08 proposed project site will remain undeveloped. KT:de H:IREPORTS\23521067ISWMP01.doc w.o. 2352·67 6/312004 3:40 PM I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER 7 -SITE BMP DESIGN VORTECHS TREATMENT UNITS 7.1 -BMP Locations The site design includes a single Vortechs treatment unit (shown on BMP Location Map located on the following page). The proposed treatment unit will located offline from the main storm drain system and is proposed in the vicinity of Alicante Road north of Street "K". 7.2 -Determination of Design Treatment Flows The 85th percentile design flow rate has been calculated using the Rational Method. Required data for the Rational Method treatment flow determination include the following: _ -Runoff Coefficient (C) = 0.63 -Rainfall Intensity (I) = 0.20 inches per hour -Drainage area to treatment unit (A) = 61.4 Ac. Runoff coefficients were derived based upon a weighted average of each area tributary to the treatment unit and the associated runoff coefficient. The following table summarizes the parameters used for determination of design flows to each of the Vortechs treatment units. DESIGN RUNOFF DETERMINATION SUMMARY TABLE Runoff 85m Percentile Treatment Unit Coefficient Rainfall (C) (inches/hour) Unit #1 0.63 0.2 Drainage 85th Pct. Area (acres) 61.4 Design Flow (cfs) 7.7 KT:de H:\REPORTS\235210671SWMP01.doc w.o. 2352·67 6/3/2004 3:40 PM I I I I I I I I I I I I I I I I I II I La Costa Greens Neighborhood 1.08 Storm Water Management Plan 7.3 -Vortechs Treatment Unit Selection The proposed Vortechs unit is an offline precast treatment unit. The 85th percentile design flow rate is forced into the treatment area by a diversion weir built in the upstream junction. Flows in excess of the design flow rate pass over the weir and proceed downstream. The following table shows the treatment capacities of the proposed Vortechs unit. VORTECHS UNIT TREATMENT CAPACITY TABLE Treatment Unit Unit #1 85m Pct. Design Flow (cfs) 7.7 Recommended Vortechs Model 9000 Treatment Capacity (cfs) 14.0 The Vortechs Model 9000, with a peak treatment flow design capacity of 14.0 cfs, was selected because of the results of the Low Flow Diversion spreadsheet, included in the Attachments section of this report, show that during the 100-yr storm the diversion weir would divert 13.5 cfs through the treatment unit. Therefore the unit has been sized to handle the flow of 13.5 cfs. KT:de H:IREPORTS1235210671SWMP01.doc w.o. 2352·67 613/2004 3:40 PM I I I I I I I I I I I I I I I I I II I VILLAGES OF LA COSTA NEIGHBORHOOD 1.08 TPI=ATIlnI=MT 1:'1 "'/\/ nCTI=CI\JlIMJlTlnr..l· •• ,,--' , •••• _ ........ "' ............. I ..... \,." ... ", \ I IV ..... Q=C*J*A TREATMENT AREA RAINFALL INTENSITY WEIGHTED CURVE NUMBER Q= 7.74 CFS 10:44 AM8/18/2003 61.41 ACRES 0.201N/HR 0.63 Sheet1RM-TREATMENT FLOW.xls I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 HYDRAULIC ANALYSIS OF LOW FLOW DIVERSION & VORTECHS UNIT AT CLEANOUT LOW FLOW ORIFICE (Q = 7.74 cfs) Weir Formula for Orifices & Short Tubes (free & submerged) n _ (""",),.."",0.5 /r-__ 04 \ """' -"'\-::;:1"1 \I...\.fll. I J Q = Ca(64.32h)o.5; C = 0.56 Q = 4.491 a(h)O.5, where a = area of orifice opening, h = head (ft) above centerline of orifice Orifice Size, L = 24 in. , a = 1.67 sq. ft., invert elevation = 100.00 ft. H = 10 in. HIGH FLOW (Q100 = 105.0 efs) Weir Formula for Bypass Weir & Vortechs Weir Q = CLH1•5; C = 3.3 for Bypass (Eqn. 2) 6.2 for Vortechs Bypass: L = 9.0 ft. @ elevation 101.50 ft. (1.50 ft.) Vortechs: L = 1.0 ft. @ elevation 105.00 ft. La Flow (Eq. 1) Wl!!ir Flow (Eq. 2) EL:!=V~ Orifice \;Iorteehs Bypass (feet) h (ft) Q (efs) H (ft) Q (efs) H(ft) 0.0 102.58 2.17 11.02 0.00 0.00 1.08 100.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.67 2.25 11.23 0.00 0.00 1.17 100.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.75 2.33 11.43 0.00 0.00 1.25 100.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.83 2.42 11.64 0.00 0.00 1.33 1'00.42 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.92 2.50 11.84 0.00 0.00 1.42 100.50 0.08 2.16 0.00 0.00 0.00 0.00 2.16 103.00 2.58 12.03 0.00 0.00 1.50 100.58 0.17 3.06 0.00 0.00 0.00 0.00 3.06 103.08 2.67 12.22 0.00 0.00 1.58 100.67 0.25 3.74 0.00 0.00 0.00 0.00 3.74 103.17 2.75 12.41 0.00 0.00 1.67 100.75 0.33 4.32 0.00 0.00 0.00 0.00 4.32 103.25 2.83 12.60 0.00 0.00 1.75 100.83 0.42 4.83 0.00 0.00 0.00 0.00 4.83 103.33 2.92 12.78 0.00 0.00 1.83 100.92 0.50 5.29 0.00 0.00 0.00 0.00 5.29 103.42 3.00 12.96 0.00 0.00 1.92 101.00 0.58 5.72 0.00 0.00 0.00 0.00 5.72 103.50 3.08 13.14 0.00 0.00 2.00 103.58 ~l17 13.32 0.00 0.00 2.08 ~ ~G~' 't~"1~ ~1Il ~ ,t ~.. ;::! t l! t 103.75 3.33 13.67 0.00 0.00 2.25 101.08 0.67 6.11 0.00 0.00 0.00 0.00 6.11 101.17 0.75 6.48 0.00 0.00 0.00 0.00 6.48 101.25 0.83 6.83 0.00 0.00 0.00 0.00 6.83 101.33 0.92 7.17 0.00 0.00 0.00 0.00 7.17 103.83 3.42 13.84 0.00 0.00 2.33 103.92 3.50 14.00 0.00 0.00 2.42 104.00 3.58 14.17 0.00 0.00 2.50 .58 1.17 8.09 0.00 0.00 0.08 O. 8.80 104.08 3.67 14.33 0.00 0.00 2.58 101.67 1.25 8.37 0.00 0.00 0.17 2.02 10.39 104.17 3.75 14.50 0.00 0.00 2.67 101.75 1.33 8.64 0.00 0.00 0.25 3.71 12.36 104.25 3.83 14.66 0.00 0.00 2.75 101.83 1.42 8.91 .0.00 0.00 0.33 5.72 14.63 104.33 3.92 14.81 0.00 0.00 2.83 101.92 1.50 9.17 0.00 0.00 .. 0.42 7.99 17.16 104.42 4.00 14.97 0.00 0.00 2.92 102.00 1.58 9.42 0.00 0.00 0.50 10.50 19.92 104.50 4.08 15.13 0.00 0.00 3.00 102.08 1.67 9.66 0.00 0.00 0.58 13.23 22.90 104.58 4.17 15.28 0.00 0.00 3.08 102.17 1.75 9.90 0.00 0.00 0.67 16.17 26.07 104.67 4.25 15.43 0.00 0.00 3.17 102.25 1.83 10.14 0.00 0.00 0.75 19.29 29.43 104.75 4.33 15.58 0.00 0.00 3.25 102.33 1.92 10.36 0.00 0.00 0.83 22.59 32.96 104.83 4.42 15.73 0.00 0.00 3.33 102.42 2.00 10.59 0.00 0.00 0.92 26.07 36.65 104.92 4.50 15.88 0.00 0.00 3.42 102.50 2.08 10.80 0.00 0.00 1.00 29.70 40.50 105.00 4.58 16.03 0.00 0.00 3.50 so USE A MODEL 9000 vortechs121nch-rm-03.xIs TOTAL Q (efs) Q (efs) 33.5 44.5 37.4 48.7 41.5 52.9 45.7 57.4 50.1 61.9 54.6 66.6 59.2 71.4 63.9 76.3 68.8 81.4 73.7 86.5 78.8 91.8 84.0 97.1 89.3 102.6 ~~~-~~~ .~ .~I ";,111 100.2 113.9 105.9 119.7 111.6 125.6 117.4 131.6 123.3 137.7 129.3 143.8 135.4 150.1 141.6 156.5 147.9 162.9 154.3 169.5 160.8 176.1 167.4 182.8 174.0 189.6 180.7 196.5 187.6 203.4 194.5 210.5 8/1812003 ------------------- APPROXIMATE VORTECHN·ICS TREATMENT AREAS Model 1000 1.6 .. 10 . 14 ·15 18 23 Model 2000 2.8 17 24 26 31 39 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 Moc;te17000 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 I ( .... I I I I' I, I I I ( ... : I I I I I I I Plan View Grit Chamber The SWirling motion created by the tangential inlet directs settleable solids toward the center of this chamb~r:. Sediment is !taught in .. " . ; the swirling flow path and settles . : back onto the pile after the storm .' ~ . event is over. . ',.... ...,' . '.1 .... .,', t: ;..: .... to '0 :. • '0 • • ", '.' '. , ....... t '. i .' Grit Chamb~r 011 Chamber/: .FloW Control Oil Chamber &: BciffIe Wall' ,', i .. . :-..... ", : ... Batfl~ Wall.. . Chamber 'The center baffle traps floatables in : .j .' ~~I§~iifi;~~~',"E'~ .: .': .'" ·:the oil chamber, 'even during clean:. .::.;.j r; . .:.out. Highly resistaflt to f1ow.surges. ".! '::: 0°' •• '0· •...... t' •• : • ""::'::::'~ " ... ''':po{ ...... . ... ,,'" Flow Control Chamber ~~,.:.! i::::?i'.1 . ;' .: ... :The weir and orifice flmV'contioi~;:~: ':d ,~:. :,;.~ ,: :.1) Rai~e 'Ievel,~nd V~lume ir. ~~. r;: :.~.:.J ' '... ' system as flaw rate Increases' and : ;;;'1 ~ .. :::.~ .. ,. '. '. . '". 2} gradually drain the:system:~s-';':;~:"::':i .'~ :':'; .. :-:. Eleva~iol))~i~w.: ~l'Y:'vy~.athe~.. " ....... flow rate subside!3: .';' .. : ";,w:.',;.. ;.:, i':~"&~~:"l ·~~~l~:~u:.~~ ... !.: ....•• :. ": ': !~ .• _.: •• ·H ....... , '0. • d' •••• _: ':':~.I.'" '::.":';: . .:.::::.!~~, .:!~~;~~j .. ..;' ... .: 1) Initial Wet Weather Phase 2) Transition Phase During a two-month storm event the water level begins to . rise above the top of the inlet pipe. This influent control feature reduce;s turbulence and avoids resuspension of pollutants. As the inflow rate increases above the controlled outflow rate, the tank fills and the floating contaminant layer accu- mulated from past storms rises. Swirling action increases at this stage, 'while sediment pile remains stable. r--~ , : I (1' 3) Full Capacity Phase , When the high-flow outlet approaches full discharge, slIJrm 4) Storm Subsidence Phase/Cleaning I drains are ffavving at peak capacil¥ The Vortechs System is designed to match your design storm flow and provide treat· ment throughout the range of storm events without bvoass- Treated runoff is decanted at a controlled rate, restoring the water level to a low dryweather volume and revealing a conical pile of sediment. The low water level facilitates inspection and dF!l'!ninn ::Inri ~innifir"I'\t1\l ... "'rlll"''''~''' ,...,~1..,""," ... " ... ", ...... ~ .... j'T.. ... I I I I I I I .. ·· . (. I I I I 1 . the Stormwater Treatment 11-41-----0 Plus 6' Typical ------;~~I Plan View To 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 design flows. Th~n simply fax or mail the worksheet to Vortechnics with your site plan, and we'll produce detailed Vortechs System scale draw· ings free of charge. 1 ~b::I5' IN\l.l -t- 3'b::I4' ~ T= Elevation View · . :; •. ,. '; :: .. : \ t, :".'::'.' :.:; ':: ... : . ;;: En9ine~rlng .:: ':'.::: .;.~.: '. .:'.' .::. : ..... ••.. AJ Fcr.in-liiie Vortech!l Sv~ms withQut it bil!l~s" sfzinQ criteria ls'lia~ed an providing ane square fact of 9ri~' .. . chambel"surtac:a area fIlr each 100 gpm of. pee~ design sb::Irm nqw rata (e.g., 1Q.year sterm], Feu: mora ".: I • • < details about Vtlrtechnlcil slzing·criteria refer to 'lcJrcachniCli TechnicaI8uUetln'3:, .' . . '. ' •• :.::';.' · : B)' Sediment s~e Y\liurl]iJ assumes. a. 3 fi,~t sump •• : • .'. . .• ::' :' .:' • :. ;. -.• ,' • • . '.~ • . " . :. ' · ~'. q. Con~tlc~ detans ·mey-wi·} d'ependirig on~the ~pecifla ;ppn~ai:ron. A~' eitara~o~ to the sfzing chart specifl-. · ':" C!llIians will appear 'Qn ~artechnic:r ~ dl~.el]~on~1 .~d :!hcP. ~ings. Pi~a~e' cell VortechnJcs far the w~lgi1t p! :sP,e-. . · .:.cific·Vortechs .system:' Ifn~~ded ••...• )' ..... ~.; •• ;' ".: .,', . , •. , ...• ' ..... ~.' . '. •. • .1.'.' ' .. , Special NDp!I:. on sb::Irsge capecity,. wh!'lO It Is. needed to..i!teet a specific' requirement fOr spill ccntainmen~, can be • •• sized to meet the sb::Irage requk'emen~'Wi~' tile selected madel. Vcrtechnics tsqhnicai staff will op.timlm systerr:\' • · ... geqrnerry to 'f!1~et cc~~inment ~equirementa witli\n II correctly .~lzed V?rtechs 6'istem, .'. .' -'. . .: :.~ .. , .. ' .. : . .... ..:. .... ; .. ,.' " ..... :. .: " .. ". .. ;~:.'N!~~ia.l?Pecm~~a~ .I?!!~r::. ~~~l~~!~ .~y .~!/~~ .. ~Qr.t~~nlc:tat (2D7] 87S~~S2 •• · :',-':':..': .... .' . 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. IJli k End Inlet To Palish Pretreatment - To aut/all I I I I I I . ~JT~_ I.' I I I I I I I . I I I· I I I I I I I I I I I I I I I I I I I I I La Costa Greens Neighborhood 1.08 Storm Water Management Plan CHAPTER8-REFERENCES "Standard Urban Storm Water Mitigation Plan -Storm Water Standards", City of Carlsbad, April 2003. "Standards for Design and Construction of Public Works Improvements in the City of Carlsbad", City of Carlsbad, California; April 1993. llMaster Drainage and Storm Water Quality Management Plan'~ City of Carlsbad, California; March 1994. "Tentative Map Drainage Study for La Costa Greens -Phase1 Neighborhoods 1.08 through 1.14," Hunsaker & Associates San Diego, Inc. April 17, 2003. "Hydrology & Hydraulic Study-La Costa GreensPhase 1", O'Day Consultants; May 25,2002 "Preliminary Storm Water Management Plan for La Costa Greens Neighborhood 1.7", Hunsaker & Associates San Diego, Inc.; May 2004. "Hydrology Manual", County of San Diego Department of Public Works -Flood Control Division; Updated April 1993. "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 of the 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 for the San Diego Basin'~ California Regional Water Quality Control Board -San Diego Region, September 8, 1994. "Vortechnics Storm Water Treatment System Manual", Vortechnics; Revised May 2000. KT:de H:\REPORTSI23521067\SWMP01.doc w.o. 2352·67 6/3/2004 3:40 PM ______________ ~-_--l V? o ~ r JTI ~ ~ II I\l Q o o , ~ Q Q Q (J\ Q o Q rORTEC:HSMODEL 9000 STORMWATER TREATMENT UNIT 7i~W--4ffU: [! tJ /,~1 , / LEGEND WATERSHED BOUNDARY OFFSITE WATERSHED -------- BOUNDARY BROW DITCH ;> ;> ;> ;> ;> OR"""" , , : 'to .~ , • I , , , :28 , mnl I , , , HUNSAKER & ASSOCIATES SAN DIEGO, INC. PlANNING 10179 Huennekens Street ENGINEERING San Diego, Ca 92121 SURVFlING PH(8S8)558·4500· FX(8S8)S58·1414 r' ) ;~'-,:;r . } .. 14 ACRES OF OFFSITE DEVELOPMENY / / / , / / / / / ~ .... / / / . ~ .... o 10~0~~~~2,0~0 ...... ~300 ~ I SCALE 1'-100' ULTIMATE CONDITION SITE MAP FOR LA COSTA GREENS NEIGHBORHOOD 1.08 CITY OF CARLSBAD, CALIFORNIA SHEET 1 OF 1