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HomeMy WebLinkAboutCT 02-21; LA COSTA GREENS NEIGHBORHOOD 1.12; PRELIMINARY STORM WATER MANAGEMENT PLAN; 2003-08-17HUNSAKER ^ASSOCIATES SAN DIEGO, INC. RECEIVED AUG 2 8 2003 PLANNING ENGINEERING SURVEYING IRVINE LOS ANGELES RIVERSIDE SAN DIEGO CITY OF CARLSBAD PLANNING DEPT. PRELIMINARY STORM WATER MANAGEMENT PLAN for LA COSTA GREENS Neighborhood 1.12 City of Carlsbad, California City of Carlsbad Project # CT 02-21 Prepared for: Real Estate Collateral Management Company c/o Morrow Development 1903 Wright Place, Suite 180 Carlsbad, CA 92008 W.O. 2352-71 August 17, 2003 DAVE HAMMAR LEX WILLIMAN ALISA VIALPANDO 101 79 Huennekens St. San Diego, CA 92121 (858) 558-4500 PH (858) 558-1414 FX www.HunsakerSD.com lnfo@HunsakerSD.com Eric Mosolgo, R.C.E. Water Resources Department Manager Hunsaker & Associates San Diego, Inc. JC;smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:52 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan TABLE OF CONTENTS SECTION Executive Summary Introduction Vicinity IVlap Post Construction BMP Location Exhibit Summary of Results storm Water Treatment Criteria and IVIethodology Introduction Regional Water Quality Control Board Criteria Identification of Typical Pollutants Conditions of Concern Design Criteria and Examples of Treatment Control BMPs Maintenance of Treatment Control BMPs Source Control BMPs Site Design BMPs storm Water Quality Treatment Best Management Practice III structural Treatment BMPs Determination of Design Treatment Flow Rational Method Treatment Flow Determination Methodology Treatment Unit Selection Attachments IV - Design Flow Determination Spreadsheets (2) - Low Flow Diversion Spreadsheet - Flow Calculations provided by Vortechnics - Voi^echnics Treatment Flow and Treatment Area Spreadsheet - Vortechnics Specification, Features and Operation - San Diego County 85th Percentile, 24-Hour Rainfall Map Land Development Manual - Quadrangle Map Watershed exhibit for La Costa Greens Developed Condition Site Map (Pocket) JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan SECTION I EXECUTIVE SUMMARY JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan EXECUTIVE SUMMARY Introduction This Water Quality Technical Report has been prepared to show methodology and calculations used to determine the sizing of the required storm water treatment unit. All calculations are consistent with criteria set forth by the Regional Water Quality Control Board's Order No. 2001-01, and the "Model Standard Urban Storm Water Mitigation Plan for San Diego County, Port of San Diego, and Cities in San Diego County." 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 1.12 is located roughly in the center of the development, east of Alicante Road, north of Neighborhood 1.13 and the SDG&E easement, and south of Neighborhood 1.09. Development of La Costa Greens Phase I consists of several individual subdivisions located within the City of Carlsbad, CA. Neighborhood 1.12 is one of the subdivisions within the La Costa Greens 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. OF MARCOS THE GREENS 1.12 VICINITY MAP NTS JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM LEGEND WATERSHED TRIBUTARY TO TREATMENT UNIT • TREATMENT UNIT 0 OFFSITE RUN-ON LOCATION LA COSTA GREENS POST-CONSTRUCTION BMP LOCATION EXHIBIT FLOW-BASED BMP FOR NEIGHBORHOOD 1.08, OFFSITE DEVELOPMEN-0 AND ALICANTE ROAD FLOW-BASED BMP FOR NEIGHBORHOOD 1.09, 1.10, A PORTION OF 1.12, AND OFFSITE DEVELOPMENT FLOW-BASED BMP FOR NEIGHBORHOOD 1.11 FLOW-BASED BMP FOR NEIGHBORHOOD 1.13,1.14, PORTION OF 1.12, ALICANTE ROAD, AND OFFSITE DEVELOPMENT Ri\0329\8.Hyd\Slte Location Map S.SxU-Ug.dwgi: 1275]Jun-12-2003il4i53 La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan 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. 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. 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. 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 I. 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. The 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 II. 32 acres respectively). Approximately 48% will remain undeveloped. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Summary of Results For Neighborhood 1.12, stormwater will be treated in one of two treatment units. Prior to discharge into either the open channel or the storm drain system in Alga Road, all storm water will pass though a proposed diversion structure that will divert the entire 85'^ percentile flow into one of the two proposed storm water treatment units. Flows in excess of the treatment flow will bypass the treatment unit. The analysis performed in this report indicates that a Vortechs Model PCI 6x24 will be required to meet the water quality treatment requirements for the northern portion of Neighborhood 1.12. The proposed Vortechs Model PCI6x24 will be located offline from the main storm drain system and is proposed to be located in the vicinity of the Street KK cul-de-sac. All stormwater runoff, including the 85'^ percentile flow, from the southern portion of Neighborhood 1.12 will be diverted to a proposed storm water treatment unit prior to discharge to the existing storm drain system. 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. In addition to the primary treatment facilitated by the proposed Vortechs Model PCI 6x24 and Model 7000, storm water treatment in excess of the Regional Water Quality Control Board requirements will be provided downstream of the storm drain outfalls. After discharge storm water from the northern portion of Neighborhood 1.12 will drain through an existing vegetated constructed channel en route to the Alga Road culverts. This vegetated channel will provide additional treatment for 85th percentile flow (by reducing the flow velocities in the channel and in turn settling out pollutants). Storm water from the southern portion of Neighborhood 1.12 will be treated in the Model 7000 then discharge into the existing Alga Road storm drain system. This system discharges into the unnamed tributary of San Marcos Creek south of Alga Road. The unnamed tributary south of Alga Road is also a vegetated channel that will provide additional treatment in the same manner as described previously in this paragraph. Since primary and additional treatment will be provided, a volume-based BMP will not be required. Maintenance of Vortechs units, which will be the responsibility of the Master Homeowners Association, is addressed in Section II of this report. The report replaces any post-construction BMP text included in the Preliminary SWPPP prepared along with the Master Tentative Map. SWPPP reports are typically required for storm water pollution prevention during interim construction activities. Desiltation basins previously designed for this project were intended only to collect sediment during the construction phase of the project and were not intended to be permanent facilities. This report specifies post-construction condition BMP treatment controls. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Anticipated pollutants of concern are included in Section II of this report. Tables included in Section II show that the proposed Vortechs system adequately treats the anticipated pollutants of concern to a degree previously determined acceptable by the Regional Water Quality Control Board. Treatment BMPs recommended for the project site are based on 85*^ percentile design flow calculations and are not based on quantitative pollutant loading analysis. Previous attempts to apply quantitative methods for estimating pollutant loading and removal efficiencies, such as in the 1993 Municipal Handbook, are no longer considered accurate for southern California. Section II also presents a listing of recommended non-structural source control BMPs, which include landscaping, urban housekeeping, etc. 85th percentile calculations included in this report were generated using the Rational Method. This method calculates the resultant 85"^ percentile flow rate based upon a peak rainfall intensity of 0.2 inches per hour. This is consistent with criteria set forth in the "Model Standard Urban Storm Water Management Plan for San Diego County, Port of San Diego, and Cities in San Diego County," JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan SECTION II STORM WATER TREATMENT CRITERIA & METHODOLOGY JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan STORM WATER TREATMENT CRITERIA & METHODOLOGY The purpose of this report is to address pollutants associated with residential developments, and to recommend techniques used to reduce the concentration of pollutant discharge into watenA^ays and bodies of water. Treatment BMPs recommended for the proposed project site are based on 85'^ percentile design flow calculations and are not based on quantitative pollutant loading analysis. Previous attempts to apply quantitative methods for estimating pollutant loading and removal efficiencies, such as in the 1993 Municipal Handbook, are no longer considered accurate for southern California. The La Costa Greens Village 1.12 project site is located in the Batiquitos watershed. After development, 85'^ percentile flow from the proposed project site will be collected in catch basins, curb inlets, and brow ditches and conveyed to one of the two proposed Vortechnics treatment units through proposed storm drain systems. After treatment, storm water from the northern portion of Neighborhood 1.12 will be discharged into a drainage swale, which will confluence with the unnamed tributary of San Marcos Creek, and ultimately into San Marcos Creek. After treatment, storm water from the southern portion of Neighborhood 1.12 will be discharged into an existing 42-inch RCP storm drain system located in Alga Road, which also discharges into an unnamed tributary of San Marcos Creek and ultimately into San Marcos Creek. San Marcos Creek is not listed as an impaired water body on the 2002 CWA Section 303(d) List of Water Quality Limited Segment 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 on^fte 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. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Most harmful pollutants accumulate within three feet of the curb. Many of these pollutants adhere to fine materials, thus avoiding removal by old-time street-sweepers. Harmful pollutants are also present in high concentrations in urban "hot spots" such as automotive, cleaning, or servicing shops. All structural BMPs shall be located to infiltrate, filter, or treat the required runoff volume or flow (based on 85'^ percentile rainfall) prior to its discharge to any receiving watercourse supporting beneficial uses. The BMPs will be designed to reduce toxin, nutrient and/or sediment loading of the 85'*^ percentile design flow from the proposed development. All grading operations for which a permit is required are subject to periodic inspection and monitoring. Flow-based BMPs shall be designed to mitigate the maximum flow rate of runoff produced from a rainfall intensity of 0.2 inch per hour. These BMPs 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. Identification of Typical Pollutants Urban runoff from a developed site has the potential to contribute pollutants, including oil and grease, suspended solids, metals, gasoline, pesticides, and pathogens to the storm water conveyance system and receiving waters. Treatment BMPs recommended for the proposed project site are based on 85 percentile design flow calculations and are not based on quantitative pollutant loading analysis. Previous attempts to apply quantitative methods for estimating pollutant loading and removal efficiencies, such as in the 1993 Municipal Handbook, are no longer considered accurate for southern California. Per the model SUSMP, this report identifies the removal efficiencies of the following pollutants using Vortechs Stormwater Treatment unit in terms of low, medium and high removal. For the purposes of identifying pollutants of concern and associated storm water BMPs, pollutants are grouped in the following general categories: Sediments are 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. Nutrients are inorganic substances, such as nitrogen and phosphorous. They commonly 6xfst 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. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Metals are raw material components in non-metal products such as fuels, adhesives, paints and other coatings. Metals of concern include cadmium, chromium, copper, lead, mercury, and zinc. At high concentrations, metals can be toxic to aquatic life. Organic Compounds are carbon-based and commonly found in pesticides, solvents, and hydrocarbons. Organic compounds can, at certain concentrations, constitute a health hazard. Dirt, grease, and grime retained in cleaning fluid or rinse water may also adsorb levels of organic compounds that are harmful or hazardous to aquatic life. Trash & Debris, such as paper, plastic, leaves, grass cuttings, and food waste, 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. Oxygen-Demanding Substances include 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. Oil and Grease are 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. JC:smm h:\sw quallty\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Table 1 below, details the typical anticipated and potential pollutants generated by various land use types, based on the draft model SUSMP prepared by the copermittees. The La Costa Greens Neighborhood 1.12 development will consist of detached single-family residences, and the Detached Residential Development category has been highlighted to cleariy illustrate which general pollutant categories are anticipated from the project area. TABLE 1 General Pollutant Categories Priority Project Categories Sediments Nutrients Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil& Grease Bacteria & Viruses Pesticides Detached Residential Development X X X X X X X Attached Residential Development x X X p(i) p(2) P X Commercial Development >100,000 ft^ p(i) 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(i) p(i) X X p(1) X p(1) Streets, Highways & Freeways X p{i) X X(4) X p(5) X Retail Gas Outlets X 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. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Conditions of Concern The Master Drainage Study for La Costa Greens addresses the City of Carisbad Standard Urban Storm Water Mitigation Plan requirements per Section III -1 C for identifying the conditions of concern. After treatment, storm water will be discharged into an unnamed tributary of San Marcos Creek and ultimately into San Marcos Creek. San Marcos Creek is not listed as an impaired water body on the 2002 CWA Section 303(d) List of Water Quality Limited Segment In order to meet water quality objectives, the pollutants that will be treated and addressed in this report are sediment, nutrients, trash and debris, oxygen demanding substances, oil and grease, bacteria and viruses, and pesticides. Design Criteria and Examples of Treatment Control BMPs Storm water quality treatment (pollutant removal) will be attained by flow-based methods. Treatment control (structural) BMPs are engineered system designs constructed to remove pollutants from urban runoff by simple gravity settling of particulate pollutants, filtration, biological uptake, media absorption, or any other physical, biological, or chemical process. Flow-based BMPs shall be designed to mitigate the maximum flow rate 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. Examples of flow-based BMPs include hydrodynamic separation devices, such as those designed by CDS Technologies, Vortechnics, HiL Technologies, etc.. For the La Costa Greens development, the storm drain system design incorporates the use of Vortechnics' Vortechs stormwater treatment units. The table on the following page compares the removal efficiencies of comparable hydrodynamic separation devices to the removal efficiencies of Vortechs stormwater treatment units. JC:smrn h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Treatment Control BMP Removal Efficiencies (1) Pollutant of Concern BMP Categories Hydrodynamic Separation Devices'^* Vortechs Stormwater Treatment System Sedinnent M-H H Nutrients L-M L-M Heavy Metals L-M L-M Organic Compounds L-M L-M Trash & Debris M-H H Oxygen Demanding Substances L L Bacteria L L Oil & Grease L-H H Pesticides L L (1) The County will periodically assess the performance characteristics 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 ofNonpoint Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database (2001), and Guide for BMP Selection in Urban Developed Areas (2001). 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 with the use of their precast treatment units. Vortechnics also provides design and system components that are cast-in-place (CIP). These CIP treatment units have the ability to treat much greater flows. 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 JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan The tangential inlet to the system creates a swiriing motion that directs settleable solids into a pile towards the center of the grit chamber. Sediment is caught in the swiriing flow path and settles back onto the pile after the storm event is over. Floatables 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. Maintenance of Treatment Control BMPs Maintenance of the site BMPs will be the responsibility of the Master Development Homeowners Association. A maintenance plan should be developed to include the following information: • Specification of routine and non-routine maintenance activities to be performed • A schedule for maintenance activities • Name, qualifications, and contact information for the parties responsible for maintaining the BMPs For proper maintenance to be performed, the storm water treatment facility must be accessible to both maintenance personnel and their equipment and materials. Amenities such as depressed curbs, hand and safety rails, gates, access roads and manholes expedite both inspection and maintenance efforts and help to reduce costs and improve efficiency. The use of strong, durable and non-corroding materials can greatly expedite maintenance efforts. These include strong, lightweight metals (orifice and weir plates), reinforced concrete for outlet structures and headwalls, disease resistant vegetation for channel bottoms and side slopes, and durable rock for gabions and riprap lining. A variety of contaminants that may be classified as hazardous or toxic may enter storm water management systems. These contaminants include heavy metals, petroleum hydrocarbons, pesticides, and a variety of organic chemicals. Federal and state laws may apply to the disposal of sediments that are captured in these storm water systems. Inlet cleaning, ditch clearing, and street sweeping are examples of other commonly used maintenance practices. Maintenancej)f Flow-Based Treatment Units Maintenance of Vortechnics units includes inspection and maintenance 1 to 4 times per year, and maintenance 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. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Flow-based storm water treatment devices should be inspected periodically to assure their condition to treat anticipated runoff. Soon after installation, the condition of the unit should be checked after every runoff event for the first 30 days. Proper inspection includes a visual observation to ascertain whether the unit is functioning properiy and measuring the amount of deposition in the unit. During the wet season, units should be inspected at least once every 30 days. Floatables should be removed and sumps cleaned when the sump storage exceeds 85 percent of capacity. The Vortechs System should be inspected at regular intervals and cleaned when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. During the wet season, units should be inspected at least once every 30 days. During construction, BMP inspections shall be performed before and after storm events and once each 24-hour period during extended storm events to identify BMP effectiveness. Inspection is the key to effective maintenance. Vortechnics recommends ongoing quarteriy inspections of the accumulated sediment. According to Vortechnics literature, the systems needs only to be cleaned when the inspection reveals that the system is neariy full - specifically, when the sediment depth has accumulated within 6 inches of the dry-weather water level. Cleanout of the Vortechs System with a "vactor truck" is generally the most effective and convenient method. 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 leaning other chambers, it is imperative that the grit chamber be drained first. The estimated annual maintenance cost associated with the Vortechs treatment unit proposed for Neighborhood 1.09, 1.10 and the northern portion of 1.12 is approximately $4,000. The estimated annual maintenance cost associated with the Vortechs treatment unit proposed for Neighborhood 1.13, 1.14, a portion of Neighborhood 1.12 is approximately $2,500. These costs will vary depending on site conditions and the frequency of runoff producing rainfall events. During the life span of the treatment unit, a record of maintenance should be kept current. This will aid in determining the frequency of maintenance activities, and therefore provide a more accurate approximation of the annual maintenance costs required to keep the unit functioning properiy. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Source Control BMPs Source controls, which are implemented to prevent or reduce the presence of pollutants and minimize the contact between pollutants and urban runoff, include the following: • 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. In the event that landscaping work requires materials such as fill, gravel, dirt, loam, mulch, etc. to be piled for more than a single day, the pile(s) should be securely covered in order to prevent suspension of the loose material in runoff from any storm event. Per the RWQCB Order, the following landscaping activities are deemed unlawful and are thus prohibited: - Discharges of sediment, pet waste, vegetative clippings, or other landscaping or construction-related wastes. • 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 impen/ious 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. JC:smm h:\sw quality\2352\71\wqtr-04.doc w.o. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan 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.). • 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. Site Design BMPs 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 the project site, 11.32 acres, will not be developed and will be preserved as open space. This will minimize the pollutant loads generated and potentially discharged from the site. Furthermore, while the project does not depend on this open space to provide treatment of potential pollutants, there will be a natural benefit derived from its existence, both as a natural buffer between the site and water bodies and as a cleansing mechanism. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan SECTION STORM WATER QUALITY TREATMENT BEST MANAGEMENT PRACTICE JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Structural Treatment BMPs The improvement design for the project site incorporates the construction of two stormwater treatment devices. Runoff from the northern portion of Neighborhood 1.12 will be treated by a Vortechs Model PC16x24 storm water quality unit, and runoff from the southern portion of Neighborhood 1.12 will be treated by a Vortechs Model 7000. The storm water quality treatment unit, treating runoff from the northern portion of the project site, has been sized to treat 85'^ percentile design flow from Neighborhood 1.09, 1.10, a portion of Neighborhood 1.12 and offsite areas to the east, all which drain through Neighborhood 1.10. The storm water quality treatment unit, treating runoff from the southern portion of the project site, has been sized to treat 85'^ percentile design flow from Neighborhood 1.13, 1.14, the southern portion of Neighborhood 1.12, and offsite areas to the east. Determination of Design Treatment Flow The 85*" percentile flow rate for the northern portion of Neighborhood 1.12 has been calculated using the Rational Method. Required data for the Rational Method Treatment flow determination is as follows: - Drainage Area (A) = 196.05 acres (Neighborhoods 1.09, 1.10, northern portion of 1.12, and offsite areas) Rainfall Intensity (I) = 0.20 inches per hour Runoff Coefficient (C) = 0.53 The northern portion of the site's overall runoff coefficient was derived based upon a weighted average of each area tributary to the treatment unit and the associated runoff coefficient. Using this method, the site's runoff coefficient was estimated to be 0.53. Bases on this data the treatment flow for the storm water treatment unit was determined to be 20.78 cfs. The 85^^ percentile flow rate for the southern portion of Neighborhood 1.12 has been calculated using the Rational Method. Required data for the Rational Method Treatment flow determination is as follows: - Drainage Area (A) = 75.92 acres (Neighborhoods 1.13, 1.14, the southern portion of 1.12, and offsite areas) Rainfall Intensity (I) = 0.20 inches per hour Runoff Coefncient (C) = 0.40 The site's overall runoff coefficient was derived based upon a weighted average of each area tributary to the treatment unit and the associated runoff coefficient. Using this method, the site's runoff coefficient was estimated to be 0.40. Bases on this data the treatment flow for the storm water treatment unit was determined to be 7.12 cfs. JC:snim h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Rational Method Treatment Flow Determination Methodology As stated in the Introduction of Section II, 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. The basic Rational Method runoff procedure is as follows: Design flow (0) = (C) * (I) * (A) Runoff Coefficient (C) - In accordance with the County of San Diego standards, the weighted runoff coefficient for all the areas tributary to the treatment unit was determined using the areas analyzed in the hydrology report. A runoff coefficient of 0.63 was used for this analysis. 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 neariy 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. Water Shed Area (A) - Project Area - Neighborhood 1.12 north totaling an area of 196.05 acres; Neighborhood 1.12 south totaling an area of 75.92 acres. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan Treatment Unit Selection Per the "Vortechnics Engineered Stormwater Products" manual, dated November, 2001 (excerpts attached), the Vortechs Model 9000 has a design flow rate of 14.0 cfs, and per the special design prepared by Scott Gorneau of Vortechnics included in a fax, dated May 20, 2003 (excerpts attached), the Vortechs Model PCI 6x24 has a design flow rate of 40.0 cfs. These units (details attached), as proposed on the improvement plans, are both configured as offline precast treatment units, meaning that the design flow rate is forced into the treatment area through a diversion structure, while flows in excess of the design flow rate pass over an inline weir and proceed downstream. The weir in the diversion structure will create a restriction, which will raise the HGL upstream of the weir. These losses will be analyzed in the Hydrology study to ensure that the potential for flooding occurrences during high return rainfall events is minimized to an acceptable level. As discussed in the Stmctural Treatment BMP section the design flow using the Rational Method was calculated to be 30.9 cfs. The Vortechs Model PCI 6x24, with a peak treatment flow design capacity of 40.0 cfs, was selected because of the results of the Flow Calculation spreadsheet, provided by Vortechnics and included in the Attachments section of this report, show that during the 100-yr storm the diversion weir would divert 39.5 cfs through the treatment unit. Therefore the unit has been sized to handle the flow of 39.5 cfs. For the southern portion, 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 11.7 cfs through the treatment unit. Therefore the unit has been sized to handle the flow of 11.7 cfs. JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM La Costa Greens - Neighborhood 1.12 Preliminary Stormwater Management Plan SECTION IV ATTACHMENTS JC:smm h:\sw quality\2352\71\wqtr-04.doc W.O. 2352-71 8/18/03 10:57 AM VILLAGES OF LA COSTA NEIGHBORHOOD 1.09, 1.10 AND PORTION OF 1.12 (NORTH) TREATMENT FLOW DETERMINATION: 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.xIs VILLAGES OF LA COSTA NEIGHBORHODD 1.13, 1.14, AND PORTIONS OF 1.12 (SOUTH) TREATMENT FLOW DETERMINATION: Q=C*I*A 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 \tirtedinics FLOW CALCULATIONS La Costa Greens Village Neighborhood Carlsbad, CA PCI6X26 System 1.10 Vortechs Orifice Cd = 0.^ A (ft^) = 6.31 Crest Elevation (ft) = 100.00 Vortechs Weir Cd = 0 Weir Crest Length (ft) = 0 Crest Elevation (ft)= 104.00 Bypass Weir Cd = 3.3 Weir Crest Length (ft)= 16 Crest Elevation (ft)= 101.5 Head Elevation Orifice Flow Weir Flow Bypass Flow Total Flow (ft) (ft) ids) (cfs) (cfs) (cfs) 0.00 100.00 0.00 0.00 O.IM o.m 0.25 100,25 1.34 0.00 Q.m 1.34 0.50 100,50 3.78 0.00 0.00 3.78 0.75 100.75 6.94 0.00 o.m 6.94 1.00 101,00 10.68 0.00 0.00 10.58 1.25 101.25 14.93 0,00 om 14.93 1.50 101.50 19.63 0.00 0.00 19,63 1,75 101.75 24.73 0.00 6.60 31.33 2,00 102.00 30.08 0,00 18.67 48.75 2,25 102.25 33.26 0.00 34.29 67.55 2.50 102,50 36.15 0.00 52.80 88,95 2.75 102.75 38.84 0.00 73.79 112.63 3.00 103,00 41.34 0.00 97.00 138,34 3.25 103,25 43.71 0.00 122.23 165.94 3.50 103,50 45,95 0.00 149.34 195,29 4.34 104,34 52,82 0.00 253.18 306.00 Calculated by: WSG 5/20/2003 iciiecked by: 105.0 104.5 104.0 103.5 103.0 102.S 102.0 101.5 101.0 100.5 100.0 99.5 Vortechs™ System Stage Discharge Curve / / ( 0,0 50.0 1CX),0 150.0 200.0 250.0 300.0 350.0 Discharge (cfs) La Costa Greens Neighborhoods 1.12,1.13, and 1.14 HYDRAULIC ANALYSIS OF LOW FLOW DIVERSION & VORTECHS UNIT AT CLEANOUT LOW FLOW ORIFICE (0= 6.07 cfs) Weir Formula for Orifices & Short Tubes (free & submerged) Q = Q = Q = Orifice Size, L = H = Ca(2ghf= Ca(64.32h)°-=; C 4.491 a(h)° =, where 16 12 in. in. 1.33 (Eqn. 1) 0.56 a = area of orifice opening, h = head (ft) above centerline of orifice sq.ft., invert elevation = 100.00 ft. HIGH FLOW (Q100 = 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. ©elevation 101.50 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. Onfice 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) 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 0.00 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 0.00 5.47 103.83 3.33 10.93 0.00 0.00 2.33 117.6 128.6 mi A'j n Qo 0.00 0.00 0.00 5.73 103.92 3.42 11.07 0.00 0.00 1 u 1.4*1 u.y^ o./o 0.00 0.00 0.00 0.00 5.73 103.92 3.42 11.07 0.00 0.00 2.42 124.0 135.0 101.50 1.00 5.99 0,00 0.00 0,00 0.00 5.99 104.00 3.50 11.20 0.00 0.00 2.50 130.4 141.6 101.58 1.08 6.23 0.00 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 vortechs12inch-rm-02.xls APPROXIMATE VORTECHNICS TREATMENT AREAS 1 Q treatment AR EA (ACR ES) " • . _ • iVIUUcL (CFS) CONDO. mm 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 Model 7000 11.0 73 102 110 132 165 Model 9000 14.0 93 129 140 168 210 Model 11,000 17.5 117 162 175 210 263 Model 16,000 25.0 167 231 250 300 375 : mm Plan View Flew Control (3iamber ;' Bevation View: Dry-Weather Grit Chamber The swirling motion created by the tangential inlet directs settleabie solids toward the center of this • chamber. Sediment is caught in . the swiriing flow path and settles "' • back onto the pile after the storm • i •event is oven • .i. Oil Chamber & Baffle Wall ' ' The center baffle traps floatables in ' 1 •the oil chamber, even during clean- . .out. Highly resistant to flow.surges. •• ! Flow Control Chambeif 1 .. •The weir and oriffca flow controis^^'-;' \ ; 1) Raise level and volume in the. ;:"•.:..;] systenh as flow r^te increasies; and V"^! 2\ gradually drain the. system, as"'', v- '-' -'i •, flow rate subsides.' ,'.. ' • .- i' i 1) Initial Wet Weather Phase During a twcmnonth storm event the water level begins to rise above the top 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, storm drains are flowing at peak capacity. The Vortechs System is designed to match your design storm flow and provide treat- ment throughout the range of storm events without bypass- "TVi orT'rtmn-ii-iWaf-Q Kl/tU \f i I : 2) Transition Phase As the inflow rate increases above the controlled outflow rate, the tank fills and the floating contaminant layer accu- mulated from past storms rises. Swiriing action increases at this stage, while sediment pile remains stable. 4) Storm Subsidence Phase/Cleaning 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 cleaning, and significantly reduces maintenance costs. The Stormwater Treatmln&lte'^' Perforatsd Covers INV B'to 9- Typical / Seal Plan View To begin the design of your Vortechs System, refer to the si2dng chart below and com- plete a Specifier's Worksheet to provide details about your site and design flows. Then simply fax or mcril the worksheet to Vortechnics with your site plan, and we'll produce detailed Vortechs System scale draw- ings free of charge. Bevation View , Engineering Notes' I'J^ir s^r^^c^Tafal fH^h TOT a'o^fe '^""^ °" Priding'cna squara foot of 'grit: , .'devils a^cuCV^IS^ni^^^g^^^S^^^^^^^^ :B)Sadlrrentstoraga\ralijni'9asaurnea.a.3footsump..• • • . ' '•, , ' ••2tiSSJ^3tSL2t^ T"**^ ^PP"""""- Arry'altoraaona to tha'Uing chart specifi- ' ••^ISSi'L^SSS^fS^^^^ to,.maat a spadflcraquirimant for apffl colttinn-ni'^'b. : 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. ry — End Inlet \ Offline \ Side Inlet ) To Pretreatment To : ncpAjvJSiDE CAJILSHAD HUNSAKER & ASSOCIATES SAN D I E C a INC PUNNING 10179 h^uemekens Sueet ENCINEERJNC San Diego, a 92121 SURVEYING PH(e5e)5SMS00- FX(BS8)55«-HH QUADRANGLE MAP WATERSHED EXHIBIT FOR LA COSTA GREENS CARLSBAD, CALIFORNIA SHEET Ri\0165\&Hyd\0165*H09-QUADMAPS,dvigC 2085:Aug-15-S003ilOi58