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CT 02-20; LA COSTA GREENS NEIGHBORHOOD 1.10 & 1.12; STORM WATER MANAGEMENT PLAN; 2004-06-23
STORM WATER MANAGEMENT PLAN for LA COSTA GREENS NEIGHBORHOODS 1.10 & 1.12 City of Carlsbad, California Prepared for: Pulte Home Corporation 5993 Avienda Encinas, Suite 101 Carlsbad, CA 92008 W.O. 2350-13 June 23, 2004 Eric Mosolgo, R.CE. Water Resources Department Manager Hunsaker & Associates San Diego, Inc. KT:de H:\REPORTS\2350M3\SWMP01.doc w o. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhoods 1.10 & 1.12 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 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 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:\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 - 85**^ Percentile Rainfall Isopluvial Map Chapter 7 - Neighborhood 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:\REPORTS\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 1.10 is located roughly in the center of the development, west of Alicante Road, east of the golf course, north of Neighborhood 1.11 and south of Neighborhood 1.08. Neighborhood 1.12 is located to the east of Neighborhood 1.10, east of Alicante Road, north of Neighborhood 1.13 and the SDG&E easement, and south of Neighborhood 1.09. Neighborhood 1.10 & 1.12 are two (2) of seven (7) 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. Neighborhood 1.10 All runoff from Neighborhood 1.10 will drain to a proposed storm drain outlet located at the southwest corner of Neighborhood 1.10 (at the Street KK cul-de-sac). Storm drain runoff discharges from this location to the unnamed tributary of San Marcos Creek, which flows in a southerly direction along the west side of Neighborhood 1.10. Runoff from Neighborhood 1.09, the northern portion of Neighborhood 1.12, and the adjacent residential development east of La Costa Greens Phase 1 will also drain to this storm drain outlet location. All stormwater draining to this location will be treated in one treatment unit prior to discharge. Neighborhood 1.12 Runoff from the northern portion of Neighborhood 1.12 will drain to a proposed storm drain outlet located at the southwest corner of Neighborhood 1.10 (at the Street "KK" cul-de-sac). This runoff discharges from the storm drain to the unnamed tributary of San Marcos Creek, which flows in a southerly direction along the west side of Neighborhood 1.10. Runoff from Neighborhood 1.09, Neighborhood 1.10, and the adjacent residential development east of La Costa Greens Phase 1 will also drain to this storm drain outlet location. Runoff from the southern portion of Neighborhood 1.12 will drain to a proposed storm drain outlet located near the intersection of Goldstone Road and Street "GG" in Neighborhood 1.14. This runoff discharges an existing 42-inch RCP in the Alga Road storm drain system. Runoff from Neighborhood 1.13, Neighborhood 1.14 and the adjacent development east of La Costa Greens Phase 1 will also drain to this storm drain outlet location. KT:de H:\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM LEGEND WATERSHED TRIBUTARY TO TREATMENT UNIT • TREATMENT UNIT ^ OFFSITE RUN-ON LOCATION B LA COSTA GREENS POST-CONSTRUCTION BMP LOCATION EXHIBIT FLOW-BASED BMP FOR NEIGHBORHOOD 1.08, OFFSITE DEVELOPMEl AND ALICANTE ROAD I ; FLOW-BASBD BMP FOR NEIGHBORHOOD 1.09, 1.10, APOFTTION OF 1.12, AND OFFSfTE DEVELOPMENT / / I I FLOVJ-BASED BMP FOR NEIGHBORHOOD 1.11 V \ ) FLOW-BASED BMP FOR NEIGHBORHOOD 1.13,1.14, PORTION OF 1.12, ALICANTE ROAD, AND OFFSITE DEVELOPMENT R:\0329\8.Hyol\Site Location Mop 8.5x11-1128.110,dwgt 1275]Jun-24-2004:12iE6 La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan Runoff from both developments 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 1.10 & 1.12 projects are is classified as Priority Projects and subject to the City's Permanent Storm Water BMP Requirements. PROJECT SITE VICINITY MAP NTS 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 two (2) Vortechs treatment units (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 forthe design of flow-based and volume- based BMPs. KT:de H:\REPORTS\2350\13\SWMP01.dDc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan 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. Neighborhoods 1.10 & 1.12 are located centrally within the development, bisected by Alicante Road, east of the golf course, south 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 Neighborhood 1.10 The La Costa Greens Neighborhood 1.10 project will include construction of four (4) 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 64 residences. The proposed project site consists of 64 residential lots and 5 open space lots, for a total area of 29.64 acres (20.33 acres and 9.31 acres respectively). Approximately 31% of Neighborhood 1.10 will remain undeveloped. Neighborhood 1.12 The La Costa Greens Neighborhood 1.12 project will include construction of two (2) 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 36 residences. The proposed project site consists of 36 residential lots and 5 open space lots, for a total area of 23.50 acres (12.19 acres and 11.32 acres respectively). Approximately 48% of Neighborhood 1.12 will remain undeveloped. The offsite developed areas, which will drain to the storm drain outlet located in Neighborhood 1.10 and 1.14 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 - Phasel Neighborhoods 1.08 through 1.14," prepared by Hunsaker & Associates San Diego, Inc. April 17, 2003. The O'Day report identified a total of 98 acres of offsite developed area that contribute flow to the La Costa development in the vicinity of the 1.09 and 1.12 Neighborhood. The Hunsaker & Associates report identified two run on locations: one at the southeast corner of Neighborhood 1.09 consisting of 19 acres of area; and one at the northeast corner of Neighborhood 1.12 consisting of 79 acres of area. KT:de H:\REPORTS\2350U3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM CARLSBAD ENONITAS WATERSHED MAP FOR LA COSTA GREENS 1.10 & 1.12 CfTY OF CARLSBAD, CALIFORNIA La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan The O'Day report identified a total of 13 acres of offsite developed area that contribute flow to the La Costa development in the vicinity of Neighborhood 1.12 and 1.13. The Hunsaker & Associates report identified one run on location near the southeast corner of Neighborhood 1.12 and the northeast corner of Neighborhood 1.13 consisting of 13 acres of area. The Quadrangle Map Watershed Exhibit for La Costa Greens illustrates the 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 sites will not cause any diversion to or from the existing watershed to the storm drain system. The proposed treatment units will be located offline from the main storm drain system and is proposed in the vicinity of Alicante Road north of Street "K" and also near the intersection of Goldstone Road and Street GG (see Ultimate Condition Site Map included in the pocket of the this report). 85'*^ percentile runoff will be treated in a storm water BMP prior to discharge. 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 developments, based on City of Carlsbad criteria. 1.4 - Results and Recommendations Using the 85'^ 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 85*'^ percentile calculations for the proposed water quality treatment units for the La Costa Greens Neighborhoods 1.10 and 1.12 developments. Table 1 - Developed Conditions BS**^ Percentile Calculations Treatment Area Drainage Area (acres) Percentile Rainfall (inches) Rainfall Intensity (inches/hour) Runoff Coefficient Neighborhoods 1.09, 1.10 & 1.12 North 196 0.67 0.2 0.53* Neighborhoods 1.13, 1.14& 1.12 South 76 0.67 0.2 0.4* *Nole: Weighted C coefficients inclusive of natural watershed. Rational Method calculations predicted 85'^ percentile runoff flows of roughly 20.8 cfs and 6.1 cfs discharging to the northern and southern treatment units respectively. KT;de H;\REPORTS\2350« 3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan Neighborhood 1.10 Priorto discharge into the open channel, storm water from Neighborhood 1.10 and northern section of Neighborhood 1.12 will pass though a proposed diversion structure that will divert the entire 85"^ percentile flow to a proposed storm water treatment unit. Flows in excess of the treatment flow will bypass the treatment unit. This analysis indicates that a Vortechs Model PCI 6x24 will be required to meet the water quality treatment requirements. The proposed Vortechs Model PCI6x24 will be located offline from the main storm drain system and is proposed in the vicinity of the Street KK cul-de-sac. Neighborhood 1.12 Prior to discharge into the existing storm drain in Alga Road, storm water from the southern section of Neighborhood 1.12 will pass though a proposed diversion structure that will divert the entire 85"^ percentile flow to a proposed storm water treatment unit. Flows in excess of the treatment flow will bypass the treatment unit. This analysis indicates that a Vortechs Model 7000 will be required to meet the water quality treatment requirements. The proposed Vortechs Model 7,000 will be located offline from the main storm drain system near the intersection of Goldstone Road and Street GG. 85**^ percentile flows will be treated in the proposed Vortechs units prior to discharging to the open channel or the existing storm drain in Alga Road. The proposed Vortechs units are offline precast treatment units. The 85'^ 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. 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\2350\13\SWMP01.doc W.O, 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 receiving 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 85"^ 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 1.10 & 1.12 projects are classified as Priority Projects 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\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM -^3 APPENDKA °nly subject to the IfaSi^J'S'"-^''-^^'^^^ . question In pit A Storm Water IMP ^2^' P^^Ject te Yea No iZpm^Si^^SMloli^ :?« Restanr^Dt = _ . Stormwater standards v7" New T i_i.. " T""'"^^"^r" areas ana ininatinn systems? Sg&g^malaial loading anri ,^inX., 1^^^'^^" .^1. handling or«,^. ex55TO^ M. w»w.wch ra.aov7stonriwMnrin..SlZi ' ^ Resource Coolral Board web ste SeoUon 2. ConstrucHon Storm Water BMP Requirements- prelect IS sui^jec to a Stomi Water PolluSn PmvTnflof P an ^P^^^^ ^"^ '""^ P-^^re but the answer to any of fte reraS Sonl' i,'^ f"^' ^ l"*^"" "N"-' prioritization in Part D, below ' construction site 31 Water standards Part D: Determine Construction Site Prioritv circumstanSf+IS'y *° cxjmplete the constmS P^°i«^' type of adjuTSrDriS,^iy£°^^^*fsattowa^^^^^ other extenuatng ' The const^fSnn"^^. t 5® P'^iects both befof^^ S^^^^^ ""^^^^ss the right to • to prdeS^lf'lj?^^^^^ NOT change consSctfen BSS construction. [Note: basis Thf' instruction BMP requjremenS mnS?, ?r^.i®^"''"e"ients that applv ^ A) High Priority 1) ^jec^^^e. the ste ie 50 acres or more and grading « oca.r during me 2) Projects 5 acres or more. 3) Proiects 5 nrme adjacent to or discharging directly to a cLtanL°^ ""^'^ °'" ^'^s^^ly . within an environmentaliy sensSJe aria ' ^ °" '"^^'^'"9 ^ateV Projects, acfive or inactive, adjacent or tributary to sensif ve water bodies • B) Medium Priority V Capital Improvement Projects where nrariin^ „ Pollution Prevention Plan (SWPPP?^T^"^'"^Stom Water Construction Pemiit (r.e.. vSter and sew2 S,"'^^ S<^« General ^"d*eetre^,IgnmeU;widenlna'c:SS&^^^ *=et frontage, eCh" s~V^S3m %re^^^ ^ 3) PemiS projects on private proper^ where 0^^^^' however, Noflce Of Intents (NS^ Spfam L^lX'" • • c; Low Priority 32 La Costa Greens Neighborhood 1.10 & 1.12 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 La Costa Greens Neighborhoods 1.10 & 1.12 developments 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. 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 \r /\ \' /\ /\ A X X^ m Attached Residential Development X X X p(1) p(2) P X Commercial Development >100,000 ft^ p(1) p(i) p(2) X p(5) X p(3) p(5) Automotive Repair Shops X X(4)(5) X X Restaurants X X X X Hillside Development >5,000 ft^ X X X X X X Parking Lots p(1) p(1) X X p{1) X p{1) Streets, Highvi/ays & Freeways X p(1) 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 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. KT:de H:\REPORTS\2350\13\SVl/MP01 .doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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-Demandinq 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:dB H:\REPORTS\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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:\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 1.10 & 1.12 sites 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 sites 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 watenways (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:\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM CARLSBAD ENQNITAS WATERSHED MAP FOR LA COSTA GREENS 1.10 & 1.12 crrv OF CARLSBAD, CALIFORNIA I I 26 Los Monos HSA (904.31) Agua Hedionda Lagoon Bacterial Indicators^ 6.8 acres 1998 Sedimentation / Siltation 27 Los Monos HSA (904.31) Agua Hedionda Creek lower portion Total Dissolved Solids lower 7 miles 2002 28 San Marcos HA (904.50) Pacific Ocean Shoreline at Moonlight State Beach Bacterial Indicators^ 0.4 miles 1998 29 Escondido Greek HA (904.60) Pacific Ocean Shoreline at San Elijo Lagoon Bacterial Indicators^ 0.44 miles 1998 30 San Elijo HSA (904.61) San Elijo Lagoon Bacterial Indicators^ 150 acres 1998 Eutrophic 330 acres Sedimentation / Siltation 150 acres 31 San Dieguito HU (905.00) Pacific Ocean Shoreline at San Dieguito Lagoon Mouth Bacterial Indicators^ 0.86 miles 1998 32 Del Dios HSA (905.21 and 905.22) Green Valley Creek Sulfate 1 mile 2002 33 Del Dios HSA Hodges Entire Reservoir Color Entire 2002 (905.21) Reservoir Entire Reservoir Nitrogen Phosphorus Total Dissolved Solids Reservoir (1104 acres) 34 Felicita HSA (905.23) Felicita Creek Total Dissolved Solids lower 0.92 miles 2002 35 Felicita HSA (905.23) Kit Carson Creek should in 905.21 HSA Total Dissolved Solids 1 mile 2002 36 Highland HSA (905.32) Cloverdale Creek Phosphorus Total Dissolved Solids 1.2 miles 2002 37 Sutherland HSA (905.53) Sutherland Reservoir Entire Reservoir Color Entire Reservoir 2002 38 Miramar Reservoir HA (906.10) Los Penasquitos Lagoon Entire Lagoon Sedimentation / Siltation 469 acres 1998 39 Miramar Reservoir HA (906.10) Pacific Ocean Shoreline Torrey Pines State Beach at Del Mar (Anderson Canyon) Bacterial Indicators^ 0.4 miles 2002 40 Scripps HA (906.30) Pacific Ocean La Jolla Shores Beach at El Paseo Grande Bacterial 3.9 miles 1998 Shoreline La Jolla Shores Beach at Caminito Del Oro Indicators^ La Jolla Shores Beach at Vallecitos La Jolla Shores Beach at Ave de la Playa last updated 9/23/2003 S:\WQS\303dllst\SD Staff Report-2002\F1NAL VERSIONS\Usted Waterbodies-2002.xls\Table 4 (Sep03 page 3 of 6 Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS 1,2 Inland Surface Waters Hydrologic Unit Basin Number BENEFICIAL USE 1,2 Inland Surface Waters Hydrologic Unit Basin Number M U N A G R 1 N D P R 0 C G W R F R S H P 0 W R E C 1 R E C 2 B 1 0 L W A R M C 0 L D W 1 L D R A R E S P W N San Dieqo County Coastal streams - continued Buena Visfa Lagoon 4.21 See Coastal Waters- Tabie 2-3 Buena Vista Creek 4.22 + • • • • • • Buena Vista Creek 4.21 + • • • • • • • Agua l-ledionda 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 W aters-Table !2-3 San Marcos Creek 4.52 + • • • • • unnamed intermittent streams 4.53 + • • • • • San IVlarcos Creek Watershed San Marcos Creek 4.51 + • • • • • Encinitas Creek 4.51 + • • • • • • Existing Beneficial Use O Potential Beneficial Use + Excepted From MUN (See Text) Beneficial use designations apply to all tributaries to the indicated waterbody, if not listed separately. Table 2-2 BENEFICIAL USES 2-27 IVIarch 12, 1997 Table 2-3. BENEFICIAL USES OF COASTAL WATERS BENEFICIAL USE Coastal Waters Hydrologic Unit Basin 1 N N A R E R E C .0 B 1 E S W 1 R A M A A Q M 1 CO D-W A S H Hydrologic Unit Basin D V c C M 0 T L R R U G W R E Number D V 1 2 M L T D E A R N M L L Pacific Ocean • Dana Point Harbor • • • • • • • • • • Del Mar Boat Basin • • • • • • • 0 • • Mission Bay • • Oceanside Harbor • • • • • • • • • • • San Diego Bay ^ • Coastal Lagoons Tijuana River Estuary 11.il • Mouth of San Diego River 7.11 • 2 Los Penasquitos Lagoon 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 recreational (REC-1) uses are prohibited. © Existing Beneficial Use Table 2-3 BENEFICIAL USES 2-47 March 12, 1997 Table 3-3. WATER QUALITY OBJECTIVES Concentrations not to be exceeded more than 10% of the time during any one year period. Constituent (mg/L or as noted) Ground Water Hydrologic Basin Unit Number TDS CI S04 %Na N03 Fe Mn MBAS B ODOR Turb NTU Color Units F Buena Vista Creek HA 4.20 El Salto HSA a 4.21 3500 800 500 60 45 0.3 0.05 0.5 2.0 none 5 15 1.0 Vista HSA a 4.22 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 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 0.5 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 4.50 1000 400 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0 Batiquitos HSA aek 4.51 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 DIEGUITO 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 1-?> 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 S.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 6.20 750 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 indicate endnotes following the table.) Table 3-3 WATER QUALITY OBJECTIVES Page 3-29 October 13, 1994 La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan Chapter 5 - FLOW-BASED BMPs 5.1 - Design Criteria Flow-based BMPs sliall 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, 85"^ 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:\REPORTS\2350M3\SWMP01.doo W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 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 85"^ percentile flow. 5.3 - Pollutant Removal Efficiency Tabie Pollutant of Concern BMP Categories Hydrodynamic Separation Devices*^' Vortechs Stormv\/ater Treatment System Sediment M-H H Nutrients L-M L-M Heavy Metals L-M L-M Organic Compounds L-M L-M Trasli & 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 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 l\/lanagement Measures for Sources of Nonpoint Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database (2001), and Guide forBh/IP Selection in Urban Developed Areas (2001). KTrde H:\REPORTS\2350M3\SWMP01.doc w o, 2350-13 6/23/2004 2;46 PM La Costa Greens Neighborhood 1.10 & 1.12 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 Vortechs Model PC 16x24 Target Maintenance Date - March 15^*^ Maintenance Activity - Annual inspection and cleanout. Clear grit chamber of each unit with vactor truck. Perform visual inspection. Remove floatables. Vortechs Model 7000 Target Maintenance Date - March 15"" Maintenance Activity - Annual inspection and cleanout. Clear grit chamber of each unit with vactor truck. Perform visual inspection. Remove floatables. KT:de H:\REPORTS\2350\13\SWMP01.doo W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan 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 Neighborhoods 1.10 & 1.12 are members of. Approximate annual maintenance costs for each of the proposed Vortechs units are outlined below. Costs assume a 3 man crew: Maintenance for Model 7000: Periodic Inspection, Maintenance and Monitoring = $800 Annual Cleanout Cost = $2,000 Maintenance for Model PC 16x24: Periodic Inspection, Maintenance and Monitoring = $800 Annual Cleanout Cost = $4,000 Subtotal = $7,600 Contingency = $760 Total = $8,360 KT:de H:\REPORTS\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water IVIanagement 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 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 - Discharges of food-related wastes (grease, food processing, trash bin wash water, etc.). KT:de H.\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water l\/lanagement 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 Neighborhoods 1.10 & 1.12 developments, 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:\REPORTS\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan CHAPTER 7 - SITE BMP DESIGN VORTECHS TREATMENT UNITS 7.1 - BMP Locations The site design includes two (2) proposed Vortechs treatment units (shown on BMP Location Map located on the following page). The proposed treatment units will be located offline from the main storm drain system and is proposed in the vicinity of Alicante Road north of Street "K" and also near the intersection of Goldstone Road and Street GG. 7.2 - Determination of Design Treatment Flows The 85*^^ 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) - Rainfall Intensity (I) = 0.20 inches per hour - Drainage area to treatment unit (A) 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 Treatment Unit Runoff Coefficient (C) 85*^ Percentile Rainfall (inches/hour) Drainage Area (acres) 85*'' Pot. Design Flow (cfs) Vortechs PC 16x24 0.53* 0.2 196 20.8 Vortechs 7000 0.4* 0.2 76 6.1 *Note: Weighted C coefficients inclusive of natural watershed. KT:de H:\REPORTS\2350\13\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan 7.3 - Vortechs Treatment Unit Selection The proposed Vortechs units are offline precast treatment units. The 85"^ 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 units. VORTECHS UNIT TREATMENT CAPACITY TABLE Treatment Unit 85*" Pet. Design Flow (cfs) Recommended Vortechs Model Treatment Capacity (cfs) Model 7000 6.1 7000 11.0 PC 16x24 20.8 PC 16x24 CUSTOM The Vortechs Model 7000, with a peak treatment flow design capacity of 11.0 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 10.9 cfs through the treatment unit. Therefore the unit has been sized to handle the flow of 10.9 cfs. The Vortechs Model PC 16x24 is a custom designed unit, due to the capacity of the flow it is required to treat. Supporting calculations supplied by Vortechnics show that this unit has been sized to handle the 20.8 cfs created by the 85^^ percentile flow. KT:de H:\REPORTS\2350M3\SWMP01.doc W.O. 2350-13 6/23/2004 2:46 PM VILLAGES OF LA COSTA NEIGHBORHOOD 1.09, 1.10 AND PORTION OF 1.12 (NORTH) Q=C*I*A TREATMENT AREA 196.05 ACRES RAINFALL INTENSITY 0.20 IN/HR WEIGHTED CURVE NUMBER 0.53 Q = 20.78 CFS 10:45 AM8/18/2003 Sheetl RM-TREATMENT FLOW.xls VILLAGES OF LA COSTA NEIGHBORHOOD 1.13, 1.14, AND PORTIONS OF 1.12 (SOUTH) Q=C*rA TREATMENT AREA 75.92 ACRES RAINFALL INTENSITY 0.20 IN/HR WEIGHTED CURVE NUMBER 0.40 Q = 6.07 CFS 12:43 PM8/18/2003 Sheetl RM-TREATMENT FLOW-12-13-14.xls Vortecils ™ Stormwater Treatment Systems TM Vortechnics FLOW CALCULATIONS La Costa Greens Village Neighborhood Carlsbad, CA PCI6X24 System 1.10 Vortechs Orifice Cd = A (ft') = Crest Elevation (ft) = 0.56 9.00 99.50 Vortechs Weir Cd = 0 Weir Crest Length (ft) = 0 Crest Elevation (ft) = 104.00 Bypass Weir Cd = 3.3 Weir Crest Length (ft) = 11 Crest Elevation (ft) = 101 Head Elevation Orifice Flow Weir Flow Bypass Flow Total Flow (ft) (ft) (cfs) (cfs) (cfs) (cfs) 0.00 99.50 0.00 0.00 0.00 0.00 0.25 99.75 1.69 0.00 0.00 1.69 0.50 100.00 4.77 0.00 0.00 4.77 0.75 100.25 8.76 0.00 0.00 8.76 1.00 100.50 13.48 0.00 0.00 13.48 1.25 100.75 18.84 0.00 0.00 18.84 1.50 101.00 24.76 0.00 0;00 24.76 1.75 101.25 31.21 0.00 4.54 35.74 2.00 101.50 38.13 0.00 12.83 50.96 2.25 101.75 45.21 0.00 23.58 68.78 2.50 102.00 49.52 0.00 36.30 85.82 First highlighted row indicates treatment of the 85th percentile flow (first flush) before bypass flow occurs. Second row indicates the elevation at which the 24 inch inlet pipe is submerged and thereby acting as the flow control into the unit. Flows greater than the 24 inch pipe capacity will most likely be bypassed. Calculated by: WSG 10/10/2003 IjChecked by: 104.5 Vortechs™ System Stage Discharge Curve c o 40.0 50.0 Discharge (cfs) 70.0 80.0 90.0 f:\data\vortechn\projects\4404ADSPC16X24.xls AP 10/10/2003 Vortechs ™ Stormwater Treatment Systems VQRTECHS SYSTEM ESTIMATED NET ANNUAL TSS REMOVAL EFFICIENCY Vortechnics La Costa Greens Village Neighborhood "^S^ Carlsbad, CA PC 16X24 • System 1.10 Design Ratio^ = (193.5 acres) x (0.53) x (449 aom/cfs) (201.1 sf) = 228.9 Bypass occurs at an elevation of 101' (at approximately 55 gpm/sf) Rainfall Intensity "/hr Ooeratinq Rate^ gpm/sf % Total Rainfall Volume' Rmvl. Effcv* (%) Rel. Effcy (%) 0.02 4.6 10.4% 98.0% 10.2% 0.04 9.2 10.1% 98.0% 9.9% 0.06 13.7 9.7% 98.0% 9.6% 0.08 18.3 8.1% 98.0% 8.0% 0.10 22.9 8.2% 98.0% 8.0% 0.12 27.5 8.6% 98.0% 8.4% 0.14 32.0 4.6% 98.0% 4.5% 0.16 36.6 4.9% 97.5% 4.7% 0.18 41.2 5.2% 96.0% 5.0% 0.20 45.8 3.6% 94.0% 3.4% 0.25 56.9 9.0% 89.0% 8.0% 0.30 64.6 5.3% 83.0% 4.4% 0.35 70.3 2.8% 78.5% 2.2% 0.40 76.1 2.7% 73.5% 2.0% 0.45 81.1 2.0% 69.0% 1.4% 0.50 85.5 0.0% 65.0% 0.0% 0.60 97.1 0.4% 52.0% 0.2% 0.70 103.4 1.6% 0.0% 0.0% 89.8% % rain falling at >0.7'7hr or bypassing treatment = Assumed removal efficiency for bypassed flows = Removal Efficiency Adjustment? = Net Annual TSS Removal Efficiency = 2.9% 0.0% 7.6% 82% 1 - Design Ratio = (Total Drainage Area) x (Runoff Coefficient) x (cfs to gpm conversion) / Grit Chamber Area - The Total Drainage Area and Runoff Coefficient is specified by the site engineer. - The conversion factor from cfs to gpm is 449. 2 - Operating Rate (gpm/sf) = intensity ("/hr) x Design Ratio. 3 - Based 10 Years of Hourly Precipitation Data From NCDC Station 7740, San Diego WSG Airport, San Diego County, CA 4 - Based on Vortechnics laboratory verified removal of 250 micron particles (see Technical Bulletin #1). 5- Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. Calculated by: WSG 10/10/2003 [Checked by: f:\data\vortechn\projects\4404ADSPC16X24.xls AP 10/10/2003 La Costa Greens Neighborhoods 1.12,1.13, and 1.14 HYDRAULIC ANALYSIS QF LOW FLOW DIVERSION & VORTECHS UNIT AT CLEANOUT LOW FLOW ORIFICE (Q= 6.07 cfs) Weir Formula for Orifices & Short Tubes (free & submerged) V—i". •/ Q= Ca(64.32h)°-^; C=0.56 Q = 4.491 a(h)''where a = area of orifice opening, h = head (ft) above centerline of orifice Orifice Size, L= 16 in. ,a= 1.33 sq.ft., invert elevation = 100.00 ft. H= 12 in. HIGH FLOW (Qioo= 130.7 cfs) Weir Formula for Bypass Weir & Vortechs Weir Q = CLH^-^ C •• 3.3 for Bypass 6.2 for Vortechs (Eqn. 2) Bypass: L = 10.0 ft. (g elevation 101.50 ft. ( 1.50 ft.) Vortechs L = 1.0 ft. @ elevation 105.00 ft. 1.50 ft.) ELEV. Lo Flow (Eq. 1) Weir Flow (Eq. 2) Lo Flow(Eq. 1) Weir Flow (Eq. 2) ELEV. Unfice Vortechs Bypass TOTAL ELEV. Orifice Vortechs Bypass TOTAL (feet) h(ft) Q (cfs) H(ft) Q (cfs) H(ft) Q (cfs) Q (cfs) (feet) h(ft) Q (cfs) H(ft) Q (cfs) J 1^ H (ft) Q (cfs) Q (cfs) 100.00 0.0 0.0 0.0 0.0 0.0 0.00 0.0 102.58 2.08 8.64 0.00 — -A L 0.00 ^ f 1.08 37.2 45.9 100.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.67 2.17 8.81 0.00 0.00 1.17 41.6 50.4 100.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.75 2.25 8.98 0.00 0.00 1.25 46.1 55.1 100.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.83 2.33 9.15 0.00 0.00 1.33 50.8 60.0 100.42 0.00 0.00 0.00 0.00 0.00 0.00 0.00 102.92 2.42 9.31 0.00 0.00 1.42 55.6 65.0 100.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 103.00 2.50 9.47 0.00 0.00 1.50 60.6 70.1 100.58 0.08 1.73 0.00 0.00 0.00 0.00 1.73 103.08 2.58 9.62 0.00 0.00 1.58 65.7 75.4 100.67 0.17 2.44 0.00 0.00 0.00 0.00 2.44 103.17 2.67 9.78 0.00 0.00 1.67 71.0 80.8 100.75 0.25 2.99 0.00 0.00 0.00 0.00 2.99 103.25 2.75 9.93 0.00 0.00 1.75 76.4 86.3 100.83 0.33 3.46 0.00 0.00 0.00 0.00 3.46 103.33 2.83 10.08 0.00 0.00 1.83 81.9 92.0 100.92 0.42 3.87 0.00 0.00 0.00 0.00 3.87 103.42 2.92 10.23 0.00 0.00 1.92 87.6 97.8 101.00 0.50 4.23 0.00 0.00 0.00 0.00 4.23 103.50 3.00 10.37 0.00 0.00 2.00 93.3 103.7 101.08 0.58 4.57 0.00 0.00 0.00 0.00 4.57 103.58 3.08 10.52 0.00 0.00 2.08 99.2 109.7 101.17 0.67 4.89 0.00 0.00 0.00 0.00 4.89 103.67 3.17 10.66 0.00 0.00 2.17 105.2 115.9 101.25 0.75 5.19 0.00 0.00 0.00 0.00 5.19 103.75 3.25 10.80 0.00 0.00 2.25 111.4 122.2 101.33 0.83 5.47 0.00 0.00 0.00 o.qo 5.47 103 s: 3r,2 ""10.93^ '•"O 00" "0.00 2 33 1176 12B 6 J0J_.42 0.92 5.73 0.00 0.00 0.00 0.00 5.73 103^92 .3.42 11'.07 0 00 0 00 2.42 124 0 130 U ""idT.'5b 5 99^ '•^6'od' ' ooo" " 0 oo' ' 0.00 '104700" 3.50 11.20 0.00 0.00 2.50 130.4 141.6 101.53 1.08 6.23 d.oo 0.00 0.08 0.79 7.03 104.08 3.58 11.34 0.00 0.00 2.58 137.0 148.4 101.67 1.17 6.47 0.00 0.00 0.17 2.25 8.71 104.17 3.67 11.47 0.00 0.00 2.67 143.7 155.2 101.75 1.25 6.70 0.00 0.00 0.25 4.13 10.82 104.25 3.75 11.60 0.00 0.00 2.75 150.5 162.1 101.83 1.33 6.91 0.00 0.00 0.33 6.35 13.27 104.33 3.83 11.72 0.00 0.00 2.83 157.4 169.1 101.92 1.42 7.13 0.00 0.00 0.42 8.88 16.00 104.42 3.92 11.85 0.00 0.00 2.92 164.4 176.2 102.00 1.50 7.33 0.00 0.00 0.50 11.67 19.00 104.50 4.00 11.98 0.00 0.00 3.00 171.5 183.4 102.08 1.58 7.54 0.00 0.00 0.58 14.70 22.24 104.58 4.08 12.10 0.00 0.00 3.08 178.7 190.8 102.17 1.67 7.73 0.00 0.00 0.67 17.96 25.69 104.67 4.17 12.22 0.00 0.00 3.17 186.0 198.2 102.25 1.75 7.92 0.00 0.00 0.75 21.43 29.36 104.75 4.25 12.35 0.00 0.00 3.25 193.3 205.7 102.33 1.83 8.11 0.00 0.00 0.83 25.10 33.21 104.83 4.33 12.47 0.00 0.00 3.33 200.8 213.3 102.42 1.92 8.29 0.00 0.00 0.92 28.96 37.25 104.92 4.42 12.58 0.00 0.00 3.42 208.4 221.0 102.50 2.00 8.47 0.00 0.00 1.00 33.00 41.47 105.00 4.50 12.70 0.00 0.00 3.50 216.1 228.8 SO USE MODEL 7000 vortechs 12inch-rm-02.xls Plan View • Grit: Chamber Oil Chamber/. Flow Control \ Baffle W^li: . Chamber 'A •••: BBvat:ioh .View: Dry-Weathep . . .M..u..tt.u:.j:*-.ij,..;4„. Grit Chamber The swirling motian created by tJie tangential inlet directs settleable solids toward the center of this . • chamber. Sediment is caught in the swirling flow path and settles' " back onto the pile after the storm •event is over. Oil ChamteV & Baffle Wail' "Tha center baffle traps floatables in .-,. - the oii chamber, even during ciean- • • • 'l^.'S^'y resistant to flow .surges. •.• - Flow Control Chaxabeif i ^ •; ....-The weir and oriffca flaw coniTol's^^'V .... Raise level and volurrie in the. u'.'" •• • ' systanh as flow rate increases;' aricj* •-. • 2]. gradually drain the'system' as"" v- ;.--. flow rate subsides.' .'.,'• .•, 'i. 'H ••^! I) Initial Wet Weather Phase During a two-month storm event the water level begins to rise above ths Cop of the inlet pipe. This influent control feature reduces turbulence and avoids resuspension of pollutants. 3) Full Capacity Phase When the high-flow outlet approaches full discharge, stonn drains are flowing st peak capacto/. The Vortechs Systsm is designed to match your design storm flow and provide treat- ment throughout the range of storm events without bvpass- 2) Transition Phase • As the inflow rate increases above the controlled outflow rate, the tank fills and tha floating contaminant layer accu- mulated from past storms rises. Swirling action increases at this stage, while sediment pile remains stable. 4) Storm Subsidence Phase/Cleaning Treated runoff is decanted at a contralled rate, restoring the water level to a low dryweather volume and revealing a conical pile of sediment The low water level facilitates inspection and clasnino. and sinnifirantK/ PPHI irpd mnint-pnnnra rnci-c Thp ths Vortecri'ei'" Stormwater Treatment System Perforated Covers Plan View To begin the design of your •Vortechs System, refer to the si2ing chart below and com- plete a Specifier's Worksheet to provide details about your site and design flows. Then 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. Sevation View *M*.;VT-'7«'t''.y'^.s:' .... ' ',ii i;;s;,U;.58QO_,'-..-.; 3/7 .• 1.B • • • •'^^ 'i- '••••V':':v4/13 •• 2.8 . 1.25 '' j- /•;;\^^•.'5/20•' • 4.5 1-75-.- ••• .•••..6/aa 6.0 2.5 .;. ••;i2^'6;;t| 8.5 3,25 8/50 11.Q • . 4.0',;.:-... • : .. .. ... ...T fjft! ;^;;:;:;.;9/G4;,. -. .,• 14.0 • " 4.75 ~ : rr-rrl? ,•'•>•..T5.'.x GV'ifl^tifj • •A::!:IQ/73 •-••.'17.5 V.ne x.iiD;;Sk ;ii ^i:^^yA2/ilS'c^:'.:' • ..'25.0: !^'f;M^!ismM kmrnmrnm • .i _ "^^Engineering Nbtaa-' .-.^^ •,• ; „ ' A) Por iivllhB VartBcha Systania without a bypass,- sizing criteria ia'tiased on prm/iding'ona squara foot o'f grit' charrhar-aurfaca araa fop aach TOO gpm atpaBl< design stomi now rata (e.g.. 1&vaar storm). For mora ••,' , ' • .dataila about Vbrtachnica siang-critaria r«fer to Vortachnica Tachnical BollEtin'S: ^ • . H) SadifTiant stnraga volume assumes. 3'3 foot sump. .•• ,,• • • .' . • q- Construction detaila may'vary' depanding on the sjjedfio .applicatfoii'. Any altarationa to tha sizing chart specifi- ' , cations wiH appaar qn VortadinicsijJimensional and shop drawings. Please'call Vortachnica for tha weight of spe-. •'dfic'Vtirtacha systama if naadad., '. ' . ;' ^' .• Special Notat Oil storage oapaci£y,.whBn it is needed to. irieat'a specific-reqiiramant fop spill containment, can ha'.' 'sized to meet tha storaga raquirement-with-tha sBlectad model. \/ortachnic3 technical staff will optimiza system/ ' geometry to.rnaBt containment raquiramenta within a correctly sized Vortacha System-. . " /iWetrib SpBoffcation Chart au^ .• - . '• . ' , -. Vortechs System Inlet/Outlet Coniigurations • Vortechs Systems can be configured to accommo- date various inlet and outlet pipe orientations. The inlet pipe con 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 \ Side Inlet To Palish H Offline • U J Ta Pretreatment Q^^Taii LEGEND WATERSHED TRIBUTARY TO TREATMENT UNIT « TREATMENT UNIT ^ OFFSITE RUN-ON LOCATION LA COSTA GREENS POST-CONSTRUCTION BMP LOCATION EXHIBIT FLOW-BASED BMP FOR NEIGHBORHOOD 1.08, OFFSITE DEVELOPME: AND AUCANTE ROAD I / FLOW-BASBD BMP FOR NEIGHBORHOOD 1.09, 1.10, APOFTTION OF 1.12, AND OFFSfTE DEVELOPMEhH" / / I i 1 / I FLOVl'-BASED BMP FOR NEIG/HB0RH00D1.11 I FLOW-BASED BMP FOR NEIGHBORHOOD 1.13,1.14, PORTION OF 1.12, ALICANTE ROAD, AND OFFSITE DEVELOPMENTT R:\032g\8,Hyd\Si-te Locntion Mop 8.5xll-1128.n0.dwg[ 1275]Jun-24-2004-18:S6 Well r > ^a.€r U A ROAD • •. ,-',-1 /.' / ^ - • ^N^.^_v . 0 ::}^ { (r itA COSTA GOLF COURSE ( SOUTHWEST ^ - A aooo 4000 6000 SCALE l'=2000' HUNSAKER & ASSOCIATES SAN D I E C 0. INC PUNNING 10179 Huemekere Street ENONEKINC Sm Diego, Ca 92121 SURVtYiNC PH{858)SSM500. F3((8S8)S58-HM QUADRANGLE MAP WATERSHED EXHIBIT FOR LA COSTA GREENS CARLSBAD, CALIFORNIA OF 1 o 5 R'\0165\S.Hyci\0165*H09-QUABHAPS,d*ot E0B53Aug-15-2003il0i5a La Costa Greens Neighborhood 1.10 & 1.12 Storm Water Management Plan CHAPTER 8 - 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. "Master Drainage and Storm Water Quality Management Plan", City of Carlsbad, California; March 1994. "Tentative Map Drainage Study for La Costa Greens - Phasel Neighborhoods 1.08 through 1.14," Hunsaker & Associates San Diego, Inc. April 17, 2003. "Hydrology & Hydraulic Study-La Costa Greens Phase 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 Departnnent 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 Distnct", 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:\REPORTS\2350M3\SWMP01.lloc W.O. 2350-13 6/23/2004 2:46 PM