The URL can be used to link to this page

Home My WebLink AboutPIP 05-03; PALOMAR FORUM LOT 6 & 7; STORM WATER MANAGEMENT PLAN - SWMP; 2005-08-16STORM WATER MANAGEMENT PLAN Keith Hansen For PALOMAR FORUM LOTS6 &7 Revised: August 16, 2005 Revised: July 5, 2005 Revised: May 2, 2005 Prepared: March 1, 2005 JN 011010-5 Prepared By: O'DAY CONSULTANTS 2710 Loker A venue West, Suite 100 Carlsbad, CA 92008 RCE 60223 Date Prepared by: JAJ -- • • • STORM WATER MANAGEMENT PLAN For PALOMAR FORUM LOTS 6 & 7 Revised: August 16, 2005 Revised: July 5, 2005 Revised: May 2, 2005 Prepared: March 1, 2005 JN 011010-5 Prepared By: O'DAY CONSULTANTS 2710 Loker A venue West, Suite 100 Carlsbad, CA 92008 o\f- Prepared by: JAJ • TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION .................................................................. 3 1. 1 Hydrologic Unit Contribution ........................................................ 3 1.2 Beneficial Uses .............................................................................. 4 2.0 CHARACTERIZATION OF PROJECT RUNOFF ............................ 5 2.1 Soil Characteristics ........................................................................ 5 2.2 Potential Discharges ....................................................................... 5 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY .... 5 3.1 Site Design BMP's ......................................................................... 5 3.2 Source Control BMP's ................................................................... 6 3.3 Treatment Control BMPs ............................................................... 6 3.4 Construction BMPs ........................................................................ 7 4.0 MONITORING, INSPECTION, AND REPORTING ........................ 8 Attachments: 1. Vicinity map • 2. Beneficial uses for the hydrologic unit 3. 303(D) list for impaired water bodies 4. Table 2: Anticipated and potential pollutants 5. Tablel: Storm Water BMP Requirements Matrix 6. Table 3: Numeric Sizing Treatment Standards 7. Summary SWMP & BMP Map 8. Source Control BMPs 9. Treatment Control BMPs 10. Insert Filters Calculations & Product Information • 2 I:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • • • STORM WATER MANAGEMENT PLAN Federal, state and local agencies have established goals and objectives for storm water quality in the region. The proposed project is a priority project as defined in Order No. 2001-01 by the San Diego Region of the California Water Quality Control Board. As a result, the project is subject to SUSMP requirements. In addition, prior to the start of construction activities, the project will comply with all federal, state and local permits including the Stormwater Management Plan (SWMP) required under the County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance (WPO) (section 67.871), the City of Carlsbad's Standard Urban Storm Water Mitigation Plan, and the National Pollution Discharge Elimination System (NPDES) from the Regional Water Quality Control Board (RWQCB). The purpose of this SWMP is to address the water quality impacts from the proposed improvements as shown on the Planned Industrial Permit. This project will provide guidelines in developing and implementing Best Management Practices (BMPs) for storm water quality during construction and post construction. Since the site is more than 1 acre, a Storm Water Pollution Prevention Plan (SWPPP) will be required. A SWPPP will be prepared and approved prior to issuance of a grading permit. The approved SWPPP shall be implemented during the construction phase. The SWPPP will consist of the selected BMPs, guidelines and activities to carry out actions, which will prevent the pollution of storm water runoff. The SWPPP will also include the monitoring and maintenance of the construction BMPs during the construction phase. 1.0 PROJECT DESCRIPTION Lots 6 & 7 of Palomar Forum are currently mass graded per approved grading plan drawing 399- 4A. A SWPPP prepared by O'Day Consultants dated June 2002 is being utilized for the construction phase of Palomar Forum. A planned industrial permit is currently being processed for Lots 6 & 7 which proposes the development of the site including buildings, parking areas, and landscape areas. 1.1 Hydrologic Unit Contribution The project is located in the Agua Hedionda Hydrologic Subarea (904.31) of the Carlsbad Hydrologic Unit in the San Diego Region. Under existing conditions, storm runoff is collected in a drainage system and conveyed into a lower canyon terrain and westerly into Agua Hedionda Creek. The proposed project will not alter the drainage discharge patterns on site. The proposed flows are consistent with those proposed in the Hydrology and Hydraulic Study for Palomar Forum, CT 99-06, dated February 3, 2003 by O'Day Consultants. (see Hydrology Study for Palomar Forum Lots 6 & 7, Developed Condition) 3 I:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • • • 1.2 Beneficial Uses The beneficial uses for the hydrologic unit are included in attachment 2, and the definitions are listed below. This information com.es from. the Water Quality Control Plan for the San Diego Basin. REC 1 -Contract Recreation: Includes uses of water for recreational activities involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, swim.ming, wading, water-skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs. REC 2 -Non-Contact Recreation: Includes the uses of water for recreational activities involving proximity to water, but not norm.ally involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, picnicking, sunbathing, hiking, cam.ping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities. MUN -Municipal and Domestic Supply: Includes uses of water for comm.unity, military, or individual water supply systems including, but not limited to, drinking water supply. COMM -Commercial and Sport Fishing: Includes the uses of water for com.m.ercial or recreational collection of fish, shellfish, or other organisms including, but not limited to, uses involving organisms intended for hum.an consumption or bait purposes. AQUA-Aquaculture: Includes the uses of water for aquaculture or m.ariculture operations including, but not limited to, propagation, cultivation, maintenance, or harvesting of aquatic plants and animals for hum.an consumption or bait purposes . SHELL -Shellfish Harvesting: Includes uses of water that support habitats suitable for the collection of filter-feeding shellfish (e.g./ clams, oysters, and mussels) for hum.an consumption, commercial, or sport purposes. IND -Industrial Service Supply: Includes uses of water for industrial activities that do not depend primarily on water quality including, but not limited to, mining, cooling water supply, hydraulic conveyance, gravel washing, fire protection, or oil well re-pressurization. EST -Estuarine Habitat: Includes the uses of water that support estuarine ecosystems including, but not limited to, preservation or enhancement of estuarine habitats, vegetation, fish, or wildlife (e.g., estuarine m.am.m.als, waterfowl, shorebirds). MAR -Marine Habitat: Includes uses of water that support marine ecosystems including, but not limited to, preservation or enhancement or marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mam.m.als, shorebirds). WILD-Wildlife Habitat: Includes uses of water that support terrestrial ecosystems including but not limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife, (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlife water food and sources. RARE -Rare, Threatened, or Endangered Species: Includes uses of water that support habitats necessary, at least in part, for the survival and successful maintenance of plant or animal species established under state or federal law as rare, threatened or endangered. MIGR -Migration of Aquatic Organisms: Includes uses of water that support habitats necessary for migration, acclimatization between fresh and salt water, or other temporary activities by aquatic organisms, such as anadrom.ous fish . 4 I:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • 2.0 CHARACTERIZATION OF PROJECT RUNOFF • • According to the CWA 2002 303(d)-list published by the RWQCB (attachment 3), Agua Hedionda Lagoon and Creek are impaired water bodies associated with the direct storm water discharge from this project. Agua Hedionda Lagoon has low priority impairment for bacteria indicators and low priority for sedimentation/siltation. Agua Hedionda Creek has low priority for total dissolved solids. 2.1 Soil Characteristics The project area consists entirely of soil group D. 2.2 Potential Discharges There is no sampling data available for the existing site condition. The project will contain some pollutants commonly found on similar developments that could affect water quality. The following list is taken from Table 2 of the City of Carlsbad's Storm Water Standards Manual (attachment 4). It includes anticipated pollutants for streets & parking lots. Streets Parking Lots • Nutrients from fertilizers • Nutrients from fertilizers • Heavy metals • Heavy metals • Organic compounds • Trash and debris • Trash and debris • Oxygen demanding substances • Oxygen demanding substances • Oil and grease from paved areas • Oil and grease from paved areas • Pesticides from landscaping • Pesticides from landscaping 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY To address water quality for the project, BMPs will be implemented during construction and post construction. Required BMPs are selected from Table 1: Storm Water BMP requirements Matrix, of the City of Carlsbad's Storm Water Standards Manual (attachment 5). 3.1 Site Design BMP's Control of post-development peak storm water runoff discharge rates and velocities is desirable in order to maintain or reduce pre-development downstream erosion. As part of the Palomar Forum mass grading plans and neighboring Raceway mass grading, a number of measures have already been taken to prevent downstream erosion. These include energy dissipators, a master detention basin, and a permanent pollution prevention basin. Rip rap energy dissipators have been placed at the outlet of all storm drains per the Forum and Raceway mass grading plans. (DWG 399-4A and DWG 409-lA, respectively) In order to control post-development peak storm water runoff discharge rates, flow from Palomar Forum will enter a detention basin adjacent to Melrose Dr. before entering Agua Hedionda Creek. The detention basin is part of the larger Rancho Carlsbad Channel & Basin Project being implemented by the City of Carlsbad. Lastly, a 5 I:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • • • permanent pollution control basin will be built as part of the Raceway project and will treat the low-flow runoff from Lots 6 & 7. T~e basin has been designed as a volume-based BMP and calculations can be found in the "Hydrology and Hydraulic Study for Carlsbad Raceway" dated June 20, 2003 by O'Day Consultants. 3.2 Source Control BMP's Source Control BMPs help minimize the introduction of pollutants into storm water in order to maintain or reduce pre-development levels of pollutants by applying the following concepts (see attachment 8 for details): Street Sweeping: Private parking lots will be swept monthly in order to reduce introduction of trash, debris, sediment and siltation into drainage systems. The HOA will be responsible for this maintenance. Also, the City of Carlsbad will sweep city streets on a routine basis. Trash Storage Areas to Reduce Pollution Introduction: Trash storage areas will be built according to the City of Carlsbad Standard Drawing GS-16. The areas will be paved with an impervious surface, graded to drain away from the enclosure, screened and walled to prevent off-site transport of trash. Trash containers will contain attached lids that exclude rain to minimize direct precipitation. Use Efficient Irrigation Systems & Landscape Design: Irrigation systems shall employ rain shutoff devices to prevent irrigation during precipitation and be designed to each landscape area's specific water requirements consistent with the Carlsbad Landscape Manual. Provide Storm Water Conveyance System Stenciling and Signage: All storm water conveyance inlets and catch basins shall provide concrete stamping, porcelain tile, inset permanent marking or equivalent as approved by the City of Carlsbad within the project area with prohibitive language satisfactory to the City Engineer. 3.3 Treatment Control BMPs As identified in Table 1 (Attachment 5), a combination of treatment control BMP's shall be incorporated into the project in order to minimize pollutants of concern from entering the storm drain system. Structural Treatment BMPs were selected by comparing a list of pollutants for which the receiving water bodies are impaired to a list of expected pollutants for each basin. Combinations of treatment BMP's that maximized priority pollutant removal were selected. The Structural Treatment BMPs selected for the site are discussed below and are shown in Attachment 9. Permanent Pollution Control Basin: As discussed in Section 3.1, a volume-based pollution control basin is currently being constructed per the Carlsbad Raceway grading plans. (DWG 409-lA) This basin will ultimately treat the high frequency storm event runoff from lots 6 & 7. 6 1:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • • • Vegetated Swale: A landscaped swale will run along the northern property line of lots 6 & 7 and treat roof runoff. A second swale to the south of buildings H and I will also treat roof runoff. Drain inlets will be placed throughout the swales to keep flow heights and velocities to a minimum. Two bio-swales will run along the top of slope along Eagle Drive. These bio-swales will pick up drainage from the parking areas and route the flows through the swale to a modified inlet with a side opening. The first bio-swale will run from the last parking space near the intersection of Eagle Drive and Palomar Airport Road north to the inlet located at the end of the parking area just south of the main entry drive. The second bio-swale picks up the drainage approximately 60 feet prior to entering the inlet located at the north end of the parking area north of the main entry drive (See Attachment 7). Storm Drain Inlet Baskets: Storm drainage inserts will be used for Structural Treatment BMPs. The drainage inserts will be catch basin and curb inlet baskets. The drainage inserts are Suntree Technologies Inc. products. (See Attachment 10 for manufacturer's information) 27 drainage inserts will be used for this project. 24 inserts will .be used in the catch basins and 3 inserts will be placed in the curb inlets located throughout the parking area. Based upon Table 3. Numeric Sizing Treatment Standards (See Attachment 6), we are using a flow-based BMP designed to mitigate (infiltrate, filter or treat) the maximum flow rate of runoff produced from a rainfall intensity of 0.2 inches of rainfall per hour for each hour of a storm event. Calculations found in Attachment 10 show the maximum amount of flow each size of insert will be required to treat. To check for adequate capacity of all the inserts on-site, the largest drainage basin for each size of catch basin/curb inlet insert was used (i.e. 18"x18", 24"x24" and 36"x36" catch basin). All three sizes of catch basin inserts and the Type B curb inlet inserts are capable of treating the maximum amount of flows produced, furthermore, the inserts are capable of treating all flows within the site. Hydrocarbon Booms: Hydrocarbon booms will be included in the catch basin inlet baskets in order to remove hydrocarbons from parking lot runoff. The booms are made of reclaimed paper products that store oils and grease, preventing leaching and draining of hydrocarbons. The booms shall be replaced yearly by the property owner or HOA. (See Attachment 10 for manufacturer's information) 3.4 Construction BMPs The following is a list of potential construction phase BMPs to be used. 1. Silt fence, fiber rolls, or gravel bag berms 2. Check dams 3. Street sweeping and vacuuming 7 I:\981022\SWMP\Lots 6 & ?\Storm Water Management Plan-rev3.doc • • 4. Storm drain inlet protection 5. Stabilized construction entrance/exit 6. Vehicle and equipment maintenance, cleaning, and fueling 7. Hydroseed, soil binders, or straw mulch 8. Material delivery and storage 9. Stockpile management 10. Spill prevention and control 11. Waste management for solid, liquid, hazardous and sanitary waste, contaminated soil. 12. Concrete waste management A SWPPP will be prepared and approved prior to issuance of a grading permit. Construction BMPs for this project will be selected, constructed, and maintained through the SWPPP to comply with all applicable ordinances and guidance documents. The approved SWPPP shall be implemented during the construction phase. 4.0 MONITORING, INSPECTION, AND REPORTING During construction, the BMPs will be monitored on a weekly basis, and observations-recorded on the included checklists (see next page). The Owner and Developer will be responsible for the monitoring and maintenance of the BMPs . 8 I:\981022\SWMP\Lots 6 & 7\Storm Water Management Plan-rev3.doc • • • BMP CHECKLIST (TO BE COMPLETED WEEKLY) DATE WEATHER INADEQUATE BMPs CORRECTIVE ACTION OBSERVATIONS G:\Accts\021040\BMP CHECKLIST.doc • • • BMP CHECKLIST (TO BE COMPLETED WEEKLY) DATE WEATHER INADEQUATE BMPs CORRECTIVE ACTION OBSERVATIONS G: \Accts\021040\BMP CHECKLIST .doc • Attachment 1 • • • Attachment 2 • Table 2=2. BENEFiCIAL USES OF INLAND SURFACE WATERS BENEFICIAL USE irniaind Surface Waters 1,2 Hydro logic M A I p G F p R R B w C w R s Unit Basin u G N R w R 0 E E I A 0 I A p Number N R D 0 R s w C C 0 R L L R w C H 1 2 L M D D E N San Diego County Coastal Streams -continued Buena Vista lagoon 4.21 See Coastal Waters-Table 2-3 Buena Vista Creek 4.22 + • • • • • • Buena Vista Creek 4.21 + • • • • • • • Agua Hedionda 4.31 See Coastal Waters-Table 2-3 Agua Hedionda Creek 4.32 • • • • • • • Buena Creek 4.32 • • • • • • • Agua Hedionda Creek 4.31 • • • • • • • Letterbox canyon 4.31 • • • • • • • Canyon de las Encinas 4.40 + 0 • • • San Marcos Creek Watershed Batiquitos lagoon 4.51 See Coastal Waters-Table 2-3 San Marcos Creek 4.52 + • • • • • unnamed intermittent streams 4.53 + • • • • • San Marcos Creek Waterslhed San Marcos Creek 4.51 + • • • • • Encinitas Creek 4.51 + • • • • • 1 Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries. • Existing Beneficial Use 0 Potential Beneficial Use 2 Beneficial use designations apply to all tributaries to the indicated waterbody, if not listed separately. + Excepted From MUN (See Text) TaDI<> 2.-2 BENEFICIAL USl:S • 2-27 September 8, 1994 • • Table 2-30 BENEFICIAL USES OF COASTAL WATERS BENEFICIAL USE Coastal Waters Hydrologic I N R R C B E w Unit Basin N A E E 0 I s I Number D V C C M 0 T L 1 2 M L D Pacific Ocean • • • • • • • Dana Point Harbor • • • • • • Del Mar Boat Basin • • • • • • Mission Bay • • • • • • Oceanside Harbor • • • • • • San Diego Bay 1 • • • • • • • • Coastal Lagoons Tijuana River Estuary 11.11 • • • • • • Mouth of San Diego River 7 .11 • • • • • Los Penasquitos Lagoon 2 6.10 • • • • • San Dieguito Lagoon 5.11 • • • • • Batiquitos lagoon 4.51 • • • • • San Elijo Lagoon 5.61 • • • • • Aqua Hedionda Lagoon 4.31 • • • • • • l11clud"5 the tidal prisms of the Otay and Sweetwater Rivers. L Fishing from shore or boat permitted, but other water contact recreational (REC-1) uses are prohibited. • Existing Beneficial Use TaLI" 2-3 8ENEFICIAL USES • 2-47 • R M A M s w s A A Q I p A H R R u G w R E E A R N M L L • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • September 8, 1 994 • • Attachment 3 • • • Attachment 4 • • • Attachment 5 • • • Attachment 6 • • • Attachment 7 • • 1 •-1~ l . d; Effici1ent Irrigation "'&1flMi"i ,.:EH41i£ji}-,:,:@/,f@ ............ +FE EE i-,.p;;.µ£i€«4AAAF?= 3? ~!-iN#t±e@ Rk'¥M.PR -6#1& ¾S • tSE-U 49i4;;a;+id,i.U t\l:Q:¥tNi llll Design timing and application methods of irrigation water to minimize the runoff of excess irrigation water into the storm water drainage system. ii Group plants with similar water requirements in order to reduce excess irrigation runoff and promote surface filtration. Choose plants with low irrigation requirements (for example, native or drought tolerant species). Consider·design features such as: Using mulches (such as wood chips or bar) in planter areas without ground cover to minimize sediment in runoff Installing appropriate plant materials for the location, in a,ccordance with amount of sunlight and climate, and use native plant materials where possible and/ or as recommended by the landscape architect Leaving a vegetative barrier along the property boundary and interior watercourses, to act as a pollutant filter, where appropriate and feasible -Choosing plants that minimize or eliminate the·use of fertilizer or pesticides to sustain growth .ploy other comparable, equally effective methods to reduce irrigation water runoff . .n.~veloping Existing Installations /arious jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of" redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be followed. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance .Manual for Stormwater Quality Control 1Ieasures, ,July 2002 . • . ::-.·..:.:.& .. ~.:--~Jc:~:.~~r.J~~.~ti .. ~;...,...a:._;r-~.r;,;:•c.;._,.:::.e<:i~t.l....._"'l'A', --•~s £'!j' ,,_..,, .:;:~..-."ii6~l.,'",~L"r.!.""..::r.-..z,.J:l.;l"Tt.~~\a .~ .1:t:....,..,.-: ... ,:_,,.1,.....,,..,...-,.u,-..l-o ........ 1]\.tD t-i .... 11-,dhr..-.l.,. _}....:i1:1.1_.~·~~~---------' • • Road and Street_ Maintenance SC-70 tE Develop paint handling procedures for proper use, storage, and disposal of paints. liil Transfer and load paint and hot thennoplmstic away from storm drain inlets. a Provide drop cloths and drip pans in paint mixing areas. 11 Propel'ly maintain application equipment. 11 Street sweep thermoplastic grindings. Yellow thermoplastic grindings may require special handling as they may contain lead. 11 Paints containing lead or tributyltin are considered a hazardous waste and must be disposed of properly. 11 Use wat~r based paints whenever possible. If using water based paints, clean the application equipment in a sink that is connected to the sanitary sewer. 11 Properly store leftover paints if they are to be kept for the next job, or dispose of properly. Concrete installation and repair 11 Schedule asphalt and concrete activities for dry weather . • Take measures to_protect any nearby storm drain inlets and adjacent watercourses, prior to breaking up asphalt or concrete (e.g. place san bags around inlets or work areas). 111 Limit the amount of fresh concrete or cement mortar mixed, mix only what is needed for the job. ~ Store concrete materials under cover, away from drainage areas. Secure bags of cement after they are open. 8e sure to keep wind-blown cement powder away from streets, gutters, storm drains, rainfall, and runoff. a Return leftover materials to the transit mixer. Dispose of small amounts of hardened excess c_oncrete, grout, and mortar in the trash. Ill Do not wash sweepings from exposed aggregate concrete into the street or storm drain. Collect and return sweepings to aggregate base stockpile, or dispose in the trash. iill When making saw cuts in pavement, use as little water as possible and perform during dry weather. Cover each storm drain inlet completely with filter fabric or plastic during the sawing operation and ,;!ontain the slurry by placing straw bales, sandbags, or :5i·avel dams around the inlets. After the liquid drains or evaporates, shovel 01~ vacuum the slurry residue from the pavement or gutter and remove from site . .Alternatively, a small onsite vacuum may be used to pick up the slurry as this will prohibit slurry from reaching storm drain il1lets. J '\Nash concrete trucks off site ot in designati.::d areas an site d~signcd to pr0clude discharge of ,,,;ash water to drainage sys~cm. ---------.......... -----=----------~-----·--~-... -·-----------·---"·-......:Z ;.-,n,~a,y '.003 C.;;;;·on11c:. SconWi,uC~1· 2,,11~ ,--lcJ11.:i'.J00i, 3 0i' 9 .·, :.'l'lv .(. 10,1·1 :J;i~ 111,.jbUuks .i.:0., 1 'C-74 Drainage System Maintenance t~ E ii s -i£i· ··-ri-HE vi?s+Wi?&--s++WESEA,ii&i~::z-tiii?+?e t:-{t ¥ i+ 31·9t··i& ·-Wtz -i-Pf?W+-~ -,-,,. ::,;H£-3P·1-+;w ™ e ?--½4•1£&9¥-44 ,4#?-&43% ·-.,s;W!I r111 Conduct inspections more frequently during the wet season for problem areas where sediment or trash accumulates more often. Clean and repair as needed. a Keep accurate logs of the number of catch basins cleaned. 11 Record the amount of waste collected. 11 Store wastes collected from cleaning activities of the drainage system in appropriate containers or temporacy storage sites in a manner that prevents discharge to the storm drain. • Dewater the wastes with outflow into the sanitacy sewer if permitted. Water should be treated with an appropriate filtering device prior to discharge to the sanitary sewer. If discharge to the' sanitary sewer is not allowe!i, water should be pumped or vacuumed to a tank and properly disposed of. Do not dewater near a storm drain or stream. 11 Except for small communities with relatively few catch basins that may be cleaned manually, most municipalities will require mechanical cleaners such as eductors, vacuums, or bucket loaders. Storm Drain Conveyance System . • Locate reaches of storm drain with deposit problems and develop a flushing schedule that • keeps the pipe clear of excessive buildup. ia Collect flushed effluent and pump to the sanitary sewer for treatment. Pump Stations iii Clean all storm drain pump stations prior to the wet season to remove silt and trash. £lJ Do not allow discharge from cleaning a storm drain pump station or other facility to reach the storm drain system. Ill Conduct quarterly routine maintenance at each pump station. ::1 Inspect, clean, and repair as necessary all outlet structures prior to the wet season. :il Sample collected sediments to determine iflandtill disposal is possible, or illegal discharges in the watershed are occm·ring. Open Channel ;.,1 Consider modification of storm channel characteristics to improve channel hydraulics, to increase pollutant removals, and to enhance channel/ creek aesthetic and habitat value. w1 Conduct channel modification/improvement in accordance with existing laws. Any person, government agency, or public utility proposing an activity that vviU change the natural (emphasis added) state of any dver, stream, or lake in Caiifornia, must enter into a steam or Lake Alteration Agreernent 'Nlth the Depaitment of Fish and Game. The davdop~r-applicant should also .::ontact local ;sovernm~nts (eity, county, s:Jccial disti.'icts), ui:hcr scate ,,_1}::11c:;::s ---••• _, ...... __ ..... -~ ----------'---·--=---·-·-·# ---· .. (:aii::an,:a Si:o.·n1wdcJr dr•1.' :;a11ctou1, 1.:;,1u,1ty -~003 ,\fi1...t1iici!J•JJ /,VJW .,~~G1\1j)f'iCHiUbUU~'\S -~Ul~l • ion5 ' tmeni Control BMPs 5.3 fact Sheet Format A BMP fact sheet is a short document that gives all the information about a particular BMP. Typically each public domain and manufactured BMP fact sheet contains the information outlined in Figure 5-1. The fact sheets also contain side bar presentations with information on BMP design considerations, targeted constituents, and removal effectiveness (if known). Treatment BMP performance, design criteria, and other selection factors are discussed in 5.4 -5.6 below. BMP Fact sheets are included in 5.7. TCxx/MPxx Example Fad Sheet Description California Experience Advantag§ Limitations Design and Sizing Guidelines Performanc~ Siting Criteril) Design Guidelines Maintenanc~ ~ References and Sources of Additional Information Figure 5-1 Example Fact Sheet 5.4 Comparing-Performance of Treatment BMPs. With a myriad of stormwater treatment BMPs from which to choose, a question commonly -dis "which one is bestn. Particularly when considering a manufactured treatment system, r 9°:gineer wants to know if it provides performance that is reasonably comparable to the L:f p1cal public-domain BMPs like wet ponds or grass swales. With so many BMPs, it is not likely that they perform equally for all pollutants. Thus, the question that each localjurisdiction faces is which treatment BMPs will it allow, and under what circumstances. What level of treatment is desired or reasonable, given the cost? Which BMPs are the most cost-effective? Current municipal storm.water permits specify the volume or rate of stormwater that must be tre~ted, but not the specific level or efficiency of treatment: These permits usually require performance to the specific maximum extent practicable (MEP), but this does not translate to an easy to apply specific design criteria. Methodology for comparing BMP performance may need to be expanded to include more than removal effectiveness. Many studies have been conducted on the performance of stormwater treatment BMPs. Several publications have provided summaries of performance (ASCE, 1998; ASCE, 2001; Brown and Schueler, 1997; Shoemaker et al., 2000; Winter, 2001). These summaries indicate a wide variation in the performance of each type of BMP, making effectiveness comparisons betwe~n BMPs problematic. 5.4.1 Variation in Performance There are several reasons for the observed variation. The Variability ofStormwater Quality •"·water quality is highly variable during a storm, from storm to storm at a site, and between ven of the same land use. For pollutants of interest, maximum observed concentrations '·u1nmonly exceed the average concentration by a factor of 100. The average concentration of a corm, known as the event mean concentration (EMC) commonly varies at a site by a factor of 5. One aspect of stormwater quality that is highly variable is the particle size distribution (PSD) of WM IN TNZr-ea::wn:emr: a:eeerrsn , cmmms 1'WRS tY • •• Section 5 Treatment Control BMPs the suspended sediments. This results in variation in the settle ability of these sediments and the pollutants that are attached. For example, several performance studies of manufactured BMPs have been conducted in the upper Midwest and Northeast where deicing sand is commonly used. The sand, washed off during spring and summer storms, skews the PSD to larger sizes not commonly found in stormwater from California sites except in mountainous areas. Consequently, a lower level efficiency may be observed if the same treatment system is used in California. Most Field Studies Monitor Too Few Storms High variabiiity of stormwater quality requires that a large number of storms be sampled to discern if there is a significant different in performance among BMPs. The smaller the actual difference in performance between BMPs, the greater the number of storms that must be sampled to statistically discern the difference between them. For example, a researcher attempting to determine a difference in performance between two BMPs of 10% must monitor many more storms than if the interest is to define the difference within 50%. Given the expense ~nd difficulty, few studies have monitored enough storms to determine the actual performance with a high level of precision. Different Design Criteria Performance of different systems within the same group (e.g., wet ponds) differs significantly in part because of differing design criteria for each system. This in tum can make it problematic to compare different groups of treatment BMPs to each other (e.g., wet ponds to vortex separators). Differing Influent Concentrations and Analytical Variability With most treatment BMPs, efficiency decreases with decreasing influent concentration. This is illustrated in Figure 5-2. Thus, a low removal efficiency may be observed during a study not because the device is inherently a poorer performer, but possibly because the influent concentrations for the site were unusually low. Also, as the concentration of a particular constituent such as TSS approaches its analytical detection limit, the effect of the variability of the laboratory technique becomes more significant. This factor also accounts for the wide variability of observations on the left of Figure 5-2. The variability of the laboratory results as the TSS approaches its analytical detection limit may also account for negative efficiencies at very low influent concentrations (e.g., TSS less than 10 mg/L). However, some negative efficiencies observed at higher concentrations may not necessarily be an artifact of laboratory analysis. The cause varies to some extent with the type of treatment BMP. Negative efficiencies may be due to the resuspension of previously deposited pollutants, a change in pH that dissolves precipitated or sorbed pollutants, discharge of algae in the case of BMPs with open wet pools, erosion of unprotected basin side or bottom, and the degradation ofleaves that entered the system the previous fall . • n5 ment Control BMPs With equation shown below, it is possible using the data from Figure 5-4 to estimate different levels of loading reduction as a function of the fraction of stormwater that is infiltrated. EEC = (t=I)(EC) + (I)(GC) Where: EEC = the effective effluent concentration I = fraction of stormwater discharged by infiltration EC = the median concentration observed in the effluent GC = expected concentration of stormwater when it reaches the groundwater To illustrate the use of the equation above, the effect of infiltration is considered on the effective effluent concentration of TSS from swales. From Figure 5-4, the median effluent concentration for swales is about 30 mg/L. Infiltration of 50% is assumed with an expected concentration of 5 mg/L when the stormwater reaches the groundwater. This gives: • EEC= (1-0.5)(30) + (0.5)(5) = 17.5 mg/L . .1'he above value can be compared to other BMPs that may directly produce a lower effluent concentration, but do not exhibit infiltration, such as concrete wet vaults. 5.4.2 Other Issues Related to Performance Comparisons A further consideration related to performance comparisons is whether or not the treatment BMP removes dissolved pollutants. Receiving water standards for most metals are based on the dissolved. fraction; the form of nitrogen or phosphorus of most concern as a nutrient is the dissolved fraction. The common practice of comparing the performance of BMPs using TSS may not be considered sufficient by local governments and regulatory agencies as there is not always a strong, consistent relationship between TSS and the pollutants of interest, particularly those identified in the 303d list for specific water bodies in California. These pollutants frequently include metals, nitrogen, nutrients (but often nutrients without specifying nitrogen or phosphorus), indicator bacteria (i.e., fecal coliform), pesticides, and trash. Less commonly cited pollutants include sediment, PAHs, PCBs, and dioxin. With respect to metals, typically, only the general term is used. In some cases, a specific metal is identified. The most commonly listed metals are mercury, copper, lead, selenium, zinc, and nickel. Less frequently listed metals a1e cadmium, arsenic, silver, chromium, molybdenum, and thallium. Commonly, only the general term "rra" is indicated for a water bo<ly without reference to a pmticufor metal. J~ 1Yesirable to know how each uf the trcatrn.ent D,\.IP'3 pf:rforrns wi(h respect tu the CL:moval of .te above pollut1nts. L't1fol·tunately, the perforrt"1<111c,~ (i:t1:=t ::m~ norh\Xi.st-:-nt oc ;i:-~ry limited for many nf the citecl n0llutants, u:;irtk.ulady i:rash, i>_-\Hs, ?CBs; diL)Xiil, mercmy, :;denium, anJ. pe.sticidcs. Fmther.non~, the conc~ntraticms t";f rhr;~:e c,)n.:,t;ti.i•~ni·s ;1rt ·;ery l1w,:, ,1tten b,2llHV the • • • Section 5 TreatmentCon~olBMPs detection limit. This prevents the detenninatio11 ofwMch BMPs are most effective. However, with the exception of trash and possibly dioxin, these poUntants readily sorb to sediments in stormwater and therefore, absent data at this time, can be considered to be removed in proportion to the removal ofTSS (i.e., sediment). Therefore, in general, those treatment systems that are most effective at removing TSS will be most effective at removing pollutants noted above. While there are little data on the removal of trash, those treatment BMPs that include a basin such as a wet pond or vault, or extended detention basin should be ~imilarly effective at removing trash as long as the design incorporates a means of retaining the floating trash in the BMP. Whether or not manufactured products that are configured as a basin (e.g.,.round vaults or vortex separators) are as effective as public domain BMPs is unknown. However, their ability to retain floating debris may be limited by the fact that many of these products are relatively small and therefore may have limited storage capacity. Only one manufactured BMP is specifically designed to remove tloating debris. There are considerable amounts of performance data for zinc, copper, and lead, with a less substantial database for nickel, cadmium, and chromium. An exception is high-use freeways where metals in general are at higher concentrations than residential and commercial properties. Lead sorbs easily to the sediments in stormwater, with typically only 10% in the dissolved phase. Hence, its removal is generally in direct propCJrtion to the removal of TSS. In contrast, zinc, copper, and cadmium are highly soluble with 50% or more in the dissolved phase. Hence, two treatment BMPs may remove TSS at the same level, but if one is capable of removing dissolved metals, it provides better treatment overall for the more soluble metals. 5.4.3 Comparisons of Treatment BMPs for Nitrogen, Zinc, Bacteria, and TSS Presented in Figures 5-5 through 5-8 are comparisons of the effluent concentrations produced by several types of treatment BMPs for nitrogen> zinc, and fecal coliform, respectively (TSS is represented in Figure 5-4). Graphs for other metals are provided in Appendix C. These data are from the Caltrans study previously cited. Total and the dissolved effluent concentrations are shown for zinc. (Note that while box-whisker plots are used here to compare BMPs, other methodologies, such as effluent cumulative probability distribution plots, are used by others.) • tion5 atment Control BMPs While a figure is provided for fecal coliform, it is i~portant to stress that the performance comparisons benveen BMPs is problemati'.:'. Some California BMP studies have shown excellent removal of fecal coliform through constructed!. wetlands and other BMPs. However, BMP comparisons are complicated by the fact that several BMPs attract wildlife and pets, thereby elevating bacteda levels. As bacteria sorb to the suspended sediments, a significant fraction may be removed by settling or filtration. A cautionary note regarding nitrogen: when comparing nitrogen re.moval between treatment systems it is best to use the parameter total nitrogen. It consi~ts of Total Kjeldahl Nitrogen -TKN(organic nitrogen plus ammonia) plus nitrate. Comparing TKN removal rates is misleading in that in some treatment systems the ammonia is changed to nitrate but not removed. Examination of the performance data of many systems shows that while TKN may decrease dramatically, the nitrate concentration increases correspondingly. Hence, the overall removal of nitrogen is considerably lower than implied from looking only at Kjeldahl Nitrogen. 5.4.4 General·Performance of Man-ufactured BMPs An important question is how the performance of manufa~tured treatment BMPs compares to those hi the. public domain, illustrated previously in Figures 5-4 through 5-8. Figure 5-9 (and Figure 5-10 in log format) presents box-whisker plots of the removal of TSS for the • nufactured systems. Data are presented for five general types of manufactured BMPs: wet Its, drain inserts, constructed wetlands, media filters, and vortex separators. The figures indicate wide.ranges in effluent concentrations, reflecting in part the different products·and design criteria within each type. Comparing figures 5-4 and 5-9 suggests that manufactured products may perform as well as the less eff~ctive public-domain BMPs such as swales and extended detention basins (excluding the additional benefits of infiltration with the latter). Manufactured wetlands may perform as well as the most effective public-domain BMPs; howeve~. the plofpre~ented in Figure 5-9 for the manufactured wetlands represents only five data points. It should be noted that each type of BMP illustrated in Figure 5-9 contains data from more than one product. Performance of particular products within that grouping may not perform as well as even the lea,st effective public-domain BMPs. This observation is implied by the greater spread within some boxes in Figure ·5:.9, for example, manufactured wet vaults and vortex separators. Product performance within each grouping of manufactured BMPs vary as follows: • Filters -TSS effluent co0;centrations range from 2 to 280 rng/L, with a median value of 29 mg/L • Inserts -TSS effluent concentrations range from 4 to 248 mg/L with a median value of 27 mg/L ;:a Wetlands -TSS effluent concentrati9ns vary little, and have a median value of 1.2 mg/L • Vaults -TSS effluent concentrations range from 1 to -+67 mg/L, v...-ith a median value of :36 mg/L ;'J Vmtex -TSS effluent concentratiGns range from 13 t0""3!°)9 mg/L, ',\ith a median v:1lue of ::;2 mg; L • -.. ;m;,p;;;z,;:.q,rcem:mwr:WeE:sor--mt:Z 1esv;mtf5t?e:v::Jii:i5WlF1 rrtsminmaf3155r1rwee::i:zn;:::r:r::n::r-r:?l'nlfeJ::e;T3T175:CT1Zr::ns1 =n: Jtrm•siJQV:GE rtara=:;;;, '<;.;;:,.,., • -aea::a-srame w .n5 reatment Control BMPs As noted earlier, performance of particular products in a grouping may be due to different design criteria within the group. For example, wet vault products differ with respect to the volume of the permanent wet pool to the design event volume; filter products differ with respect to the type of media. 5a4a5 Technology CertificatRon This Handbook does not endorse proprietary products, although mariy are described. It is left to each community to determine which proprietary products may be used, and under what circumstances. When considering a proprietary product, it is strongly advised that the community consider performance data. b~t only performance data that have been collected following a widely accepted protocol. Protocols have been developed by the American Society of Civil Engineeing (ASCE BMP Data Base Program), and by the U.S. Environmental Protection Agency (Enviromental Technology Certification Program). The local jurisdiction should ask the manufacturer of the product to subniit a report that describes the product and protocol that was followed to produce the performance data. It can be expected that subsequent to the publishing of this Handbook, new public-domain tic nologies will be proposed (or design criteria for existing technologies will be altered) by : opment engineers. As with proprietary products, it is advised that new public-domain ' •-.;1.,; nologies be considered only if performance data are available and have been collected .Jllowing a widely accepted protocol. 5.5 BMP Design Criteria for Flow and Volume Many municipal stormwater discharge permits in California contain provisions such as Standard Urban Stormwater Mitigation Plans, Stormwater Quality Urban Impact Mitigation Plans, or Provision C.3 New and Redevelopment Performance Standards, commonly referred to as SUSMPs, SQUIMPs, or C.3 Provisions, respectively. What these and similar provisions have in common is that they require many new development and redevelopment projects to capture and then infiltrate or treat runoff from the project site prior to being discharged to storm drains. These provisions include minimum standards for sizing these treatment control BMPs. Sizing standards are prescribed for both volume-based and flow-based BMPs. A key point to consider when developing, reviewing, or complying with requirements for the sizing of treatment control BMPs for storm water quality enhancement is that BMPs are most efficient and economical when they target small, frequent storm events that over time produce more total runoff than the larger, infrequent storms targeted for design of flood control facilities. The reason for this can be seen by examination of Figure 5-11 and Figure 5-12. Figure 5-11 shows the distribution of storm events at San Jose, California where most storms produce less than 0.50 in. of total rainfall. Figure 5-12 shows the distribution ofrainfall , .sities at San Jose, California, where most storms have intensities ofless than 0.25 in/hr. 1 ~ ., patterns at San Jose, California are typical of other locations throughout the state. Figures .-11 and 5-12 show that as storm sizes increase, the number of events decrease. Therefore, \~hen B1[Ps are designed for increasingly larger storms (for ex:ample, storms up to 1 in. versus storms of up to 0.5 in.), the B:MP size and cost increase dramatically, ""hile the number uf additional • • Section 5 Treatment Control BMPs It is important to note that arbitrarily targeting large, infrequent storm events can actually reduce the pollutant removal capabilities of some BMPs. This occurs when outlet structuresp detention times, and drain down times are designed to accommodate unusually large volumes and high flows. When BMPs are over-designed, the more frequent, small storms that produce the most annual runoff pass quickly through the over-sized BMPs and therefore receive inadequate treatment. For example, a detention basin might normally be designed to capture 0.5 in. of runoff and to release that runoff over 48 hrs, providing a high level of sediment removal. If the basin were to be oversized to capture 1.0 in. of runoff and to release that runoff over 48 hrs, a more common 0.5 inch runoff event entering basin would drain in approximately 24 hrs, meaning the smaller, more frequent storm that is responsible for more total runoff would receive less treatment than if the basin were designed for the smaller event. Therefore, efficient and economical BMP sizing criteria are usually based on design criteria that correspond to the "knee of the c1:1rv~" or point of diminishing returns. 5.5.1 Volume-Based BMP Design Volume-based BMP design standards apply to BMPs whose primary mode of pollutant removal depends on the volumetric capacity of the BMP. Examples of BMPs in this category includes detention basins, retention basins, and infiltration. Typically, a volume-based BMP design criteria calls for the capture and infiltration or treatment of a certain percentage of the runoff from the project site, usually in the range of the 75th to 85th percentile average annual runoff volume. The 75th to 85th percentile capture range corresponds to the "knee of the curve" for many sites in California for sites w}:iose composite runoff coefficient is in th~ 0.50 to 0.95 range. The following are eJCamples of volume-based BMP design standards from current municipal stormwater permits. The permits require that volume-based BMPs be designed to capture and then to infiltrate or treat stormwater runoff equal to one of the following: • : · • Eighty (Bo)% of the volume of annual runoff, determined in accordance with the methodology set forth in Appendix D of the California Storm Water Best Management Practices Handbook (Stormwater Quality Task Force, 1993), using local rainfall data. • The maximized storm water quality capture volume for the area, based on historical rainfall records, determined using the formula and volume capture coefficients set forth in Urban Runoff Quality Management (WEF Manual of Practice No. 23/ ASCE Manual of Practice No. 87, (1998), pages 175-178). The reader is referred to the municipal stormwater program manager for the jurisdiction processing the new development or redevelopment project application to determine the specific requirements applicable to a proposed project. California Stormwater Bi\-IP Handbook Approach The volume-based B:vIP sizing methodology included in the first edition of the California Storm Water Best Management Practice ffcmdbook (Stormwater Quality Task Force, 1993) has been included in this second ellitinn 1)f the handbook and is the mdhcd recommen1.led for use. • on5 tmant Control BMPs In the third example, the Uniform Intensity Approach, the rainfall intensity is specified directly, and is not a function of the location or time of concentration of the area draining to the BMP. This approach is very simple to apply, but it is not reflective oflocal conditions. The three example flow-based BMP design criteria are easy to apply and can be used in conjunction with the Rational Formula, a simplified, easy to apply formula that predicts flow rates based on rainfall intensity and drainage area characteristics. The Rational Formula is as follows: Q=CiA where Q = flow in fta/s i = rain intensity in in/hr A = drainage area in acres ! • C = runoff coefficient .a.ne Rational Formula is widely used for hydrologic calculations, but it does have a number of limitations. For stormwater BMP design, a key limitation is the ability of the Rational Formula to predict runoff from undeveloped areas where runoff coefficients are highly variable with storm intensity and antecedent moisture conditions. This limitation is accentuated when predicting runoff from frequent, small storms used in storm water quality BMP design because many of the runoff coefficients in common use were developed for predicting runoff for drainage design where larger, infrequent storms are of interest. Table 5-3 provides some general guidelines on use of the Rational Equation. Table 5-3 Use of Rational Formula for Stormwater BMP Design Composite Runoff Coefficient, "C" BMP Drainage Area o.ooto 0.25 o.26too.5O 0.51 to 0.75 0.76 to 1.00 (Acres) Oto25 Caution Yes Yes Yes 26 to 50 High Caution Caution Yes Yes 51 to 75 Not High Caution Caution Yes Recommended 76 to 100 Not High Caution Caution Yes Recommended -7. summary, the Rational Formula, when used with commonly tabulatt3d runoff coefficients in ,1developed drainage areas, will likely result in predictions higher than will be experienced under actual field conditions. However, given the simplidty of the equation, its use n~rnains • • Section 5 TreatmentConuolBMPs practical and is often the standard method specified by local agencies. In general, use of alternative formulas for predicting BMP design flows based on the intensity criteria above is acceptable if the formula is app.roved by the local flood control agency or jurisdiction where the project is being developed. The following steps describe the approach for application of the flow-based BMP design criteria: 1. Identify the "BMP Drainage Area" that drains to the proposed BMP. This includes all areas that will contribute runoff to the proposed BMP, including pervious areas, impervious areas, and off-site areas, whether or not they are directly or indirectly connected to the BMP. 2. Determine rainfall intensity criteria to apply and the corresponding design rainfall intensity. a. Factored Fl.ood Flow Approach: Determine the time of concentration for "BMP Drainage Area" using procedures approved by the local flood control agency or using _ standard hydrology methods. Identify an Intensity-Duration-Frequency Curve representative of ~e drainage area (usually available from the local flood control agency or climatic data center). Enter the Intensity-Duration-Frequency Curve with the time of concentration and read the rainfall intensity corresponding the 50-yr return period rainfall event. This intensity is the "Design Rainfall Intensity." b. CaliforniaStormwater BMP Handbook Approach: Select a rain intensity cumulative fr~quency curve representative of the "BMP Drainage Area." See Appendix D. Read the rainfall intensity corresponding to the cumulative probability specified in the criteria, usually 85%. Multiply the intensity by the safety factor specified in the criteria, usually 2, to get the "Design Rainfall Intensity." c. Uniform Intensity Approach: The "Design Rainfall Intensity'' is the intensity specified in the criteria, usually 0.2 in/hr. 3. Calculate the composite runoff coefficient" "C" for the "BMP Drainage Area" identified in Step 1. 4. Apply the Rational Formula to calculate the "BMP Design Flow" a. Factored Flood Flow Approach: Using the "BMP Drainage Area" from Step 1, the "Design Rainfall Intensity" from Step 2a, and "C" from Step 3, apply the Rational Formula and multiply the result by 0.1. The result is the "BMP Design Flow." b. California Stormwater B.1.vlP Handbook Approach: Using the "BMP Drainage Area" from Step 1, the "Design Rainfall Intensity" from Step 2b, and "C" from Step 3, apply the Rational Formula. The result is the "BMP Design Flow." • c. Uniform Intensity Approach: Using the ''B1IP Drainage A.rea" from Step 1, the •'Design Rainfall Intensity" from Step 2.c, :.md ''C" from Step 3, apply the Rational Formula. The result is the ''BMP Design Flow." aCSii!nsra::::arns,,-:rrarws 71P:ane:::r eern,c::i,, .~r t[C:=30 Vegetated Swale C -F· ifmk -4/i-3iii4ft--H5 fSd,1fi4i-<dQW \51-...:t.gj. "llR·;:il ., 46#¥1 1• -·-id#SI\S{fi ..§ ?5 i-·'-r -e ... ,. ,--H+•b•,S•r?5,:\i•(• •f-,.l-,._3111;++1 .. w,1•,1 >Hj,S.-,f ..... U,AZU•-r!i • S31F+fi<59fi establishment. Where runoff diversion is not possible, cover graded and seeded areas with suitable erosion control materials. Maintenance The useful life of a vegetated swale system is directly proportional to its maintenance frequency. If properly designed and regularly maintained, vegetated swales can last indefinitely. The maintenance objectives for vegetated swale systems include keeping up the hydraulic and removal efficiency of the channel and maintaining a dense, healthy grass cover. Maintenance activities should include periodic mowing (with grass never cut shorter than the design flow depth), weed control, watering during drought conditions, reseeding of bare areas, and clearing of debris and blockages. Cuttings should be removed from the channel and disposed in a local composting facility. Accumulated sediment should also be removed manually to avoid concentrated flows in the swale. The application of fertilizers and pesticides should be minimal. Another aspect of a good maintenance plan is repairing damaged areas within a channel. For example, if the channel develops ruts or holes, it should be repaired utilizing a suitable soil that is properly tamped and seeded. The grass cover should be thick; if it is not, reseed as necessary. Any standing water removed during the maintenance operation must be disposed to a sanitary • wer at an approved discharge location. Residuals (e.g., silt, grass cuttings) must be disposed accordance with local or State requirements. Maintenance of grassed swales mostly involves maintenance of the grass or wetland plant cover. Typical maintenance activities are summarized below: ■ Inspect swales at least twice annually for erosion, damage to vegetation, and sediment and debris accumulation preferably at the end of the wet season to schedule summer maintenance and before major fall runoff to be sure the swale is ready for winter. However, additional inspection after periods of heavy runoff is desirable. The swale should be checked for debris and litter, and areas of sediment accumulation. ■ Grass height and mowing frequency may not have a large impact on pollutant removal. Consequently, mowing may only be necessary once or twice a year for safety or aesthetics or to suppress weeds and woody vegetation. 11 Trash tends to accumulate in swale areas, particularly along highways. The need for litter removal is determined through periodic inspection, but litter should always be removed prior to mowing. ■ Sediment accumulating near culverts and in channels should be removed when it builds up to 75 mm (3 in.) at any spot, or covers vegetation. ■ Regularly inspect swales for pools of standing water. Swales can become a nuisance due to mosquito breeding in standing water if obstructions develop ( e.g. debris accumulation, • invasive vegetation) and/ or if proper drainage slopes are not implemented and maintained. :;:;;n;, rer:z-:r:2¥ er rzmr -= -mer en:v&:se 6 of 13 California Stormwater BMP Handbook January 2003 VeL41ated s.wale • Table 3 Estimated Maintenance Costs (SEWRPC. 1991 l component UnltCo&t Lawn Mowing $0.8511,000 WI mowing General Lawn Care $9.0011,000W/year Swale Debris and Litter $0.10 /linearfDCtl,ear Removal Grass Reseeding with $0.30lyd2 Mulch and Fertilizer Program Administration and $0.15 / linaar fact I year, Swale Inspection plus $25 / inspection Total .. January 2003 Swale Size (Depth and Top Width) 1.5 Foot Depth, One,. 3-Foot Depth. 3-Foot Foot Bottom Width. Bottom Width. 21.foot 10-FootTop Width TopWldth $0.14 t linaarfaot $0.21 IHnaarfDDt $0.181 linaarfoot $0.28 /Dnearfoot to.10 / linaarfoot $0.10 I li11G1ar foot $0.01 /linaarfoot $0.01 /0naarfoot $0.15 /linaarfoot $0.151 linear foot $0.Si I linear foot $ 0.75 llinur foot California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com TC-30. r EiW· ~3 #U Comment Lawn maintonance arCB=(top width + 10 filat) x langth. Maw eight timos par yaar Lawn maintananca araa = {top width + 10 feat) x length - Area ravsga1iilad aquals 1 % aflawn malntonancaaraa i»r yar Inspect four timas per year - 9 of 13 • Attachment 10 • • • • This section of the Indian River is a Class 2 water body~ with a Shellfish Harvesting classification bringing· intense scrutiny from the St Johns River Water Management District. Corp of Engineers permitting is required for new outfalls in the area due to seagrasses near the shoreline. • The park, the school, and Oak Street lie in unincorporated Brevard County. The church, and properties west of the school are in Melbourne Beach. Being a collector roa~ all of the utility companies have ,_major transmission lines in the road right-of-way. As can be seen, this challenging project involved Brevard County, Melbourne Beach, the School Board, Brevard County Parks and Recreation Department, Brevard County Road and Bridgo Departmen'9 Brevard County Stonnwater Utility, a church, three different Homeowne1s Associations, a soccer club, the Water Management District, the Corp of Engineers, and several utility companies. Stakeholder involvement and partnerships were going to be critical to weave a solution through the many players involved. Propo"d Improvements The first priority was to alleviate flooding in the homes adjacent to the school. As an interim measure, a berm was designed and constructed by County personnel along the south property µnes of the school, with a swale behind the berm directing water to the southernmost point of the school property. At that location, an inlet and 18" out1all pipe were constructed in a utility easement through two heavily landscaped and fenced yards, to Pompano Street, where it was tied into an existing stonn drain pipe. A short time later, heavy rains overflowed the berms and swales and flooded homes adjacent to the school again. CEI was engaged at that point to provide more effective drainage improvements. Fortunatelylt Gemini Elementary School had a significant area of vacant land on their site. Toe school entered into agreements with Brevard County allowing the construction of three dry retention ponds totaling 2.95 hectare to reduce flows leaving the school site, as well as provide stonnwater treatment where none existed. TI1ese dry ponds were wound .around several soccer and ~asebaU :fields. T'ime .soccer field's locatioms :bad to t.ernain in ~:,lace due to previous agreements with the school and Parks and Recreation Dept. The )Onds were anly 26-40 cm (12"-18") :1eep and sodded, allowing t:he so,:cer teams to use ·t;1e p-ond areas as practice fleids '\,/hen dry. ·-,;11}:en tl1e ;onds we:r.e ,::xi:a'vat~d, 'Jle confining clay !ayar 'J✓as .:-emoved to allow ~br :n.filtratim1 &ough ite 'teach ;3:and J.t ·.~~.e site. Construction was scneduloo during rhe Slm.'lmer when school was rn.rt . • • • The treatment strategy involved maximizing treatment methods within the project basin with alternative Bl\ilPs, as well as retrofitting two adjacent watersheds as additional mitigation. A total of 1.67 acre feet of retention storage was provided in Phase 2 in the roadside swales and small ponds. This was equivalent to 0.032 inches of retention from the drainage areas flowing to the retention areas. A treatment train along Oak Street was designed by using 9 Orated Inlet Skimmer Boxes, from Suntree Technologies, Inc., in the new inlets to trap debris entering the inlets, constructing berms to slow runoff from the ball fields, and installing one baffle box at the downstream end of the new pipe system along Oak Street. Baffle Boxes are in-line stonnwater treatment devices which trap sediment, trash, and debris. They have been used by Brevard County successfully for the last 9 years. In offsite Basin 4, which only bad one existing baffle box to provide sediment removal, 16 Curb Inlet Skimmer Boxes were installed in all of the existing inlets to provide nutrient removal by trapping grass clippings, leaves, and yard debris. Nutrients were a concern in the canals since the nutrients promote algae blooms, which in tum increase muck build up in the canals. In offsite drainage Basin S, there are 3 existmg pipes which discharge directly to the canals. Three baffle boxes and 6 curb inlet skimmer boxes were designed to provide sediment and nutrient treatment fur this drainage basin. Brevard County Stonnwater Utility will implement this project and be responsible for all maintenance of the improvements. The baffle boxes will be inspected twice a year and cleaned as needed. The inlet traps will be cleaned twice a year.. Brevard Cowrt.y has a vacuum truck dedicated to cleaning stonnwater BMPs .. Using numerous BMPs used on this project provided a high degree of treatment for the new piping system along Oak Street, and prC;)vided treatment for two offsite basins where little treatment existed. The retrofitting of the offsite areas was, in effect, mitigation for the new discharges to the canal See Exhibit 1 for a map of the improvements. In Phase l of the project, the dry po.ads and out:fiul pipes were modeled hydraulically using the Intercomnected Pond Routing program. Since the dry ponds hi the Phase 2 project area were too small to pmvide .effective attenuation, the predevelopm.ent a;i.:d post development runoff calculations were made using Hydraflow and the ratio1.1.al method. "fhe only available storm draim pipe fur Ptase 2 was a 36" pipe in offsite Basin 4. The i:~w piping a!oi11g Oak Street was .:mmected to d:e ,~isting 36" pipe, a-.:d -.rte piping downstream of the conr..ection was upgraded to a 42" pipe. The pipes were designed for a 25 year storm. :Basins 112, aud 3 were 1 t,auch lor.ger distam.ce 3.om ~~:e .outfall than 3asin 4. A..s a r~su1t of different tim.-"S of conce-.atration, the peak flows :from 3asin 4 passed sooi.1er th.an Basins 1,2, and 3, giving only a slight increase ill peak d~scharge, ' • dd' • ? "5 ' ' • ·• ~ • 1 • • "' 'I ·:espn:e a mg L.-11cc"!.ares m c.:e i(.:a i'..OW:.itg to rn~ ex1st11;g outra, . .-1. ... ::.e ;..:Lcr_t:~.11 ~:::,t • .. :~~·::;a,:;.;.i )\.~~..:.~:;..,:1£ .. ,.:: .. :.::.:~s ~1 ~·~::.~ ;::.-· .. &J .$~-::;;~ .. ~1:.1 ·--r.:...~ ~ ~.:. .. :.:::;:;..: -~:.=-~c:~:?..: -: ~;}~,:.c~A~S. ri~~-~se -::i .. "":.3..~S ; .. ~,j :1 ~-::~~~i.c .. y .: I"'.: .... ~~~:...~.~ .:.,..: .. ~:~·st:(~_t.S .;~,-~-=:;; S--t l) ~-.~::£~:\ :,.:J ·:._ .. ! • residents did not want to increase the liequency of costly dredging. The main pollutants of concern leading to muck deposition in the canals were Total Suspended Solids (TSS), Total Nitrogen (TN), and Total Phosphorus (TP). Sediment build up at the end of the pipes was common. Nutrient loadings from grass clippings, leaves, and fertilizers leads to algae blooms and low dissolved oxygen in the canals, which in turn leads to muck build up from the eutropbication process. Most of the material dredged from residential canals is typically muck. • • To address tbis concern, a pollutant loading analysis of the existing and proposed stonnwater discharges was performed. In the existing conditio~ the only stormwater treatment for the canal system was a baffle box along Cherry Street for offsite Basin 4 of 24.24 hectares. There were a total of 7 outfall pipes discharging into the canal system. In the first pbase of this project stormwater treatment was provided for 8.02 hectares of the school grounds with 3 dry detention ponds. The discharge from these ponds was to the Indian River, rather dlall the canal system, so these pollutant loads were not included in the pollutant load analysis for the canal outfall. The existing pollutant load tp the canal only came from the drainage Basins 4 and 5, totaling 31.2 hectares. The runoff from Oak Street did not drain to the canal in existing conditions, only in the post development conditions . The strategy for the pollutant analysis was to calculate the pollutant loads in the existing conditions, and then calculate the pollutaht loads after the new pipes were added to the system and off'site areas retrofitted for storm.water: treatment. The pollutants used in this analysis were TSS, TP, and TN. Each drain.age basin was categorized by land use. Areal, annual, tnass loading :i:ates from 11Stomiwater Loading Rate Parameters for Central and South Florida", Harper, 1994, were multiplied by each basin's area_ to give existing and potential arunual pol_h.atant loadings. See Table 1. llr.e next step was to calculate the pollutant removal rates for the different BlV.iPs. Individual BMP removal e:fficiencies were take from •cA Guide for 3~ Selection in Urban Developed Areas'\ EWRI, 2000. Wb.at was dhal!ei1.ging '-with thls :a:inaUysiis -was the use of multiple BMPs in series for the treatment tr.am.. Each 3~./iP receives cleru:er ar.d clean.er ·water .as me •.;vater rooves down the tt-a.in.. At ,~h BM.P, the removal-efficiency J:ir .eich cor.stituent -;;.ias multiplied by -:he :re~mg fel[tCentage ,:}f i:he :'.:.itfal :oadmg ::o give a weighted, cu.nclative,. rem.-oval .eincie:ecy fol' ;;a-ch ccri .. st~11,eat. 200 Tut.le 2. ~.ll.7-~e:se calculated ramoval ef.5.ciencies -N~;,e then .i1.1a1tipE,,;d by ·me -~om ,:afou1ated l=-oilutant loads to give t~:e r~duced pollutant loadings a·fter u'1.e B:MPs 'Nere installed. See Table 3. Table 4 shows that the ~otal loads to i:1':e canal were :»:educed ss a result of d;.e. ;.;t.\ofitthig of .. msite ai-:d oJ"srte basins . • quality components to water quantity project~ communities can help achieve pollution remediation goals being established for NPDES, T.1MDL9 and PLRG programs. Retrofitting existing stonnwater systems to provide water quality treatment is more complicated, expensive, and time consuming than traditional stormwater designs for new development. The scarcity of available land and numerous existing utilities in older built out areas will tax an engineer's imagination to provide innovative BMPs in these locations. An carefully planned treatment train was designed consisting of swales, ponds, berms, baffle boxes, and inlet traps 1Q provide overall stonnwater pollution reduction. In order to address stormwater pollution concerns, treatment mitigation was designed in offsite drainage basins. The pollutant loadings and removals were calculated using a simple but effective spreadsheet analysis incorporating the latest in BMP efficiency studies. While complicated storm.water modeling software can be used for pollutant analysis, this type of modeling is more cost effective on large basin studies than small basins and individual projects. The pollutant removal calculations showed an annual net reduction of 79% for TSS, 37% fot Total Phosphorus, and 24% for Total Nitrogen in the Oak Street basin despite the creation of a new stormdrain system for a landlocked area. As this project demonstrates, there are typically numerous stakeholders that need to be brought into the project early in the process and kept in tile process throughout the life of the project. Many meetings were held with city, county, and state officials, homeowners associations, schools, soccer clubs, churches, and utility compani~ All it takes is one uncooperative stakeholder to set back or. kill a project, as was demonstrated with the church backing out of the land acqwsjtion pr<>cess after many verbal indications of approval Using creative partnerships with other entities and agencies allowed the development of' a unique strategy to solve flooding at several locations in the project area. References ASCE -"Guide For Best Management Practice Selection in Urban Developed Areas", 2001 Gordon England, P.E. "PoUutant Rerooval T~stmg For a Suntree T.echno!og:es Grate Inlet Skimmer Box", 2001 ·• • • Background Methodology Results IABLE OF CQNTENT§ Tabla 1 -Sediment Sleva Analysis Conclusions APPENDIX A ► Site Photos APPENDIX& PAGE 1 2 2 3 3 ► Universal Engineering Sciences Grate Inlet Skimmer :aox !valuation Report UNIVERSAL ENGINEERING SCIENCES Ca1S1iara ~ Geaectrical El\gineemg" ~ ~ • ~ Materials Tesmig• l'lwshcld ~ 820 Brevard Avenue • Rockledga, Florida 32955 (321) 638-0808 Fax (321) 638-0978 November 2, 2001 Mr. Gordon England, P.E. Creech Engineers. Inc. 4450 West Eau Gallie Boulevard Melbourne, Florida 32934 Reference: Grate Inlet Skimmer Box Evaluation . Northwest Comer of South Brevard Avenue and South 8111 Street Cocoa Beach, Brevard County, Florida Universal Project No. 33186-002-01 Universal Report No. 51479 Dear Mr. England: • Universal Engineering Sciences, Inc. (Universal) has completed an evaluation of a Grate Inlet Skimmer Box {GISB) in accordance with Universal Prop-0sal No. P01-0781. The evaluation was conducted to document the pollutant removal effectiveness at the above-referenced site. A Location Map, Site Map and Site Photographs are presented as Attachments 1. 2 and 3, • respectively. Sediment Testing Universal supplied the sediment sample for the GISB evaltJJation. The sediment sample consisted of fine sands. coarse grain sands with crushed shells. and gravel. A gradation analysis of the sediment sample (S-1) was perfonned, prior to GISB penonnance tasting. The percentages of soil grains, by weig~t, ratained on each sieve were measured and a grain size distribution curve generated, to determine the textural nature of the sample and provide a control (baseline) prior to fieldwork. A sediment sampUe of known weight (57.87 lbs.) was p~aced on the pavement upstr'eam of the GlSB and washad into the GiSB •,vith a portable water source snmuiating a stou-n, ,event. T'ir.e --::aptured sediment 'Nas then removed from iha GiSB, dried and weighed. The captured sediment weighed 42.41 lbs. resulting in a loss of 15.46 lbs. \Tom ifrta G!S8 testing. A gradation anaiysis of 'lha captured sediment sample (S-2) was ;::;errom.s:oo. Universal completed particle size analyses on ·Jle two rapr3sertativs s3dirr.ant samples {S-1 ~nd S-2). "ii1a samples we(s tasted according to iJ~a proo..,~111-..ss -~or m.achan!cat ~1.a•Al:Q of ASTM D 422 (Standard Method for Particia Siza Ai1alysis of Soils). ln part, Afff:VI D 422 ;.squires passing each specimen over a standard aet of r.ested sE~vas (¾ :11ch, ~:o. 4, ,'{o; ·; 0, >1o. 40, No. 50, .\lo. 100, t-1o. 200). Tiia p;&rc.antage 0f tr:e scil grnir:s r.afa;r;.sd on 8a.;i1 3!.:=va iza ;.ua determined to provide ·me graii1 size dismbution of the sample. i''hs dlstiibu(icn determines .r .. !!i. -~,.~·1·--"I ,. ..... ,:., ... ~ ..,.:•." .... ·:1. ~,!I···· ........ ~:::?!.-... .1i •. : ... \,.. ~" ... \._,..,( ... •• ...... ··•,'4\ ......... ' ... ~-~-.-... ·"'t .......... • ..... : •• •• ... "" .. ,.•.J .,:; ... , .. ..ii~..:t. ~.C4\..,.,_.1.., IJi d,v ...,i-..,;; ~.o~i.,..;,.,,J •. :.i. .. ,\J ..:..,~_;.:» .tl.l ~.,.,:.t;U,.,~'-.1.i,';:J ~--~ -.:;~.~-:111•\"~~~ •. Si_ .. ~~~-=-~..: .. ~L . ..:.1 •• ~..;~. • ATTACHMENT 2 SITE MAP • ATTACHMENT 3 SITE PHOTOGRAPHS , __ _, ~.,. 1,-'" P""~·i, ~:;.;..~·n ... i\Ji."~" kf ~~fw ~I -- ·=·, 1...··o, FL 32765 Mj "°'tt-3oij~'r'i~1 Chain ··o. ~pJ--. _,todyl - Page_.~ Dale: ·--• .,.!·,L,.' • ., .. ··;;:: ........ -..:.::...:..,_ --· ··-· -. Nii·; ---___ _:,) -. ; .. .. ~. ~::.:~ ___ !i.;z,:..:.-'tl!~; . .3}1',e.J\ AV ,--;, 1C.b ___ .,_,,.._ ' , ,--~ -·----l.ZJ.•~9··[5~ ~1-_2:..·;,l b .. ~J "-L . :,, . - 'I.I.I.Ii.(: \ , , h:-t ! .Jl ---~-;,;.; '".:. <. -/i~J\L1 1 e"'w: >n.~J ~ -..~ .. ~ ..,_ .,,,, .;;, ,· ·-PAA; ----..;;;,: .J r~- r-·-··~-- c~ m OA,;;~ • i ii i I t ~Z(p /Di /t'-lZu • I><- ------·----- -r ___ e: ~ _ .. ___ _ . ---~r ...... --- ------- ,-·-····--........ -,_ .. r· -·-· --·- ri-------- --- -. ··--· _., ___ [····•··-- fl···-- --- -· - --·· .. I ! ' 1 ~ If~ i~ ~~ 'A K I t··----·- 'Nuubrli.:.D -\_ .. .!L.L~ ..2:.~·'·-~-·--~~--~~;=(RECE!Vc~~ . -~--<:(u ~01 fi /.~a .. ,// --DJlTE!TIME '1;'/;E --✓----._J '4.J,J I ,I -iifl·. ...:..:. • . ---......_..,..-,,, ·--. f. 11::a~ F ....... -----~--. -. .. C\L Ji-;.:-.tr\.,,,H.,,ta vwih-,:.;•i'f.$: ,::.. -· 't:i(:,.;1111 1-.<· • -~ ~~ ·-::ea-· :-xr ---.. --. . ~: a;._,_ ....... ----· ,_ ...... s: ..... -:... ------. " -, • "'"'"'. ~ • - -., --- . .,. . . -.. Atl!ALVSIS REQUl:STEO ~ I .'15 .. . I ·z .2 PROJi:CT INFORMATION SAMPLE RECEIPT PROJ~NAME: /,-ll$J" ~~~ '&O)C i:.VAJ1 l~J Totaa # ol Containers PIIOJf.CT#! Chain of CUlitody Seill. IITE~kci5: ~ ~~, h.... Rccv'd llll Good CondWolll PltQJEef~~~~ PO#: INVOICE TO: ~ Pnliad,. -• .,.. • -• -----·. .icture of Grate Inlet Skimmer Box '.[t{~1~~j~(~~~J[l?)Y ., • • •• -·~ ;i: :_:; •, The Reedy Creek Improvement District (RCID) selected six (6) test sites in 'the Lake Buena Vista area to evamate fuo perfomumce of these units. One unit was placed in a cwb inlet along Hotel Plm &clevard to trap lmdscspe leaf litter, sediment, and oil & grease from a high use roadway. Three (3) units were placed in the backstage service area of tho Rain Forest Cafo. Two (2) ·units were placed in the backstage service area of the McDonald's restaumnt md IAgos merehandise ~lb.op. After .sevel-al field inaemigs, dming ~;vhlch Si.mtree :cok ~:<.tensive mezs~.t.-er~~ents, ~1:1otos, and other documentation of each st.oimwster drain, the Gt·ate 1ilet Skimmer 3oxes were -r,1m1ufacrured ;.nd deliveroo fur ~fafilioo. All mam -~,1erll :rs-iaeoo ·Niiott :i:aish~p ' ' 1 ' 1.-1 ,. •~ • "-1'\1\ ('1 ' ),, • 1' .I r"' , ,,1, l-1 ·::.)pm>mn~re y ',,"'NO 'N•~:ut i:-~m:re ·:::'°;,e l':in 1-.J~fi.S'~Gis r.oJtc-.ay :~21ocn. _:i::e -~£f1. ·:.:r.c~ )~riod for ;i~iicle catcha11ent was one ;11cnth. ·Mr. Jfomy ~d Tom Ra~pel, Suatree Txhnologies, visited ,!ach site several 'imes dudng j:e i.-r.c;nth ·:o ~~1swe ±at cebris '\VCitid :-:ot :511 the :.:nits ~oo ioon. ·"'-T~.,.,".~·y ..,., 2•"'CO ~•.m:~ . .a. ,..,..-1:,...,,d •!·e ... ·x vii .., . .:..; ... at -w1 .,., , ---u. ~'" ~-..,1, ·""" :... J., J:.e skirnri:er box~s w~s :~mo'.r~d, ~?le:.Si~~j, • • units performed u expected removing oo a-mage, 20 pounds of debris from each of ilie six sitese The compooition of debris varied considerably. The Hotel Plaza (roadway) site was 9fJ% leaf litter and 10% sediment The Rain Forest Cafe sites ran in opposition as you got close to the lake. First inlet was about 50% leaf litter and cigarette butts and 500/4 sediment Tho middle inlet was 60 % sediment and 30 % leaf litter (lotA miscellaneous). Tho inlet closest to the lab was 95% sediment and 5% leaf litter. The two sites at the McDonalds/Legos area were similar to aach other. The site closest tn the lake was 95% sediment and 5% leaf litter. Tho site closest to the entrance· gate was 93% litter sediment and 2% leaf litter. i_:_:_: ____ -~_:_:_: . .,:_·-~-:··· .. ::~--'._._·.,:_i_(_'. .. _,.Y:,:t:' .•. • •.~.;~3 .. -=:t:,"❖l, . ~. :·-~. ' /:~ t I· , .I I .;. •I ' ··l::..~ This composition is indicative of the human :activities ;md drainage flow patterns of tr.at site. :Backstage meas in the Walt Disney World Resort :.eceiva .m nficial :cain event e~ch nigh~ durilllg cle2K!ing ~p~rations. This washes a oontm.ual flow over ;:he impervicm mte, washmg 311 matenais mto tl1e stormw~ter system. • Collecwd swrapwa werti pi~ • and ane by the RCID Environmental Services Laboratol)'. Analysis parilile~r were: Amille>~ Chfla»cal Oxygen Demand, Fecal Colifom1 (MPN), N'ltrite and Nitrate, Total • Kjeld&bl Nitrogen, Oil and Grease, Total Phospbate, Suspemed· Solids, and Metals. ;~yfiill itsults ire p~ied in tM followhig table: Pollutant % Al~ili.. Y~~ LC;CA'taoN LAiil NO. VJiJ.UE UNITS SAIi-DAT& Change Ciumae AIYuli\.ltii;i;.1 $eiill}~~w Rf-IN 1846 o.aa m,I 09Fab-00 0.14 Art10.uftic.1 ~ii.liO,~\\ii RF-OUT 1646 0.23 • OB-Fflb.00 AmtnufliA, ti~it;yli-.w RF-OUT-I 1646 0.25 '"" 09-Flb.QO Ch~tnlefii oxyiiJ1iofl Deh·wrKi RF-IN 164& 2kr/0 • oa-Feb,00 1036 Chi;iatllt.iil 0-.ICy~i• Dt.irhwld Rf-OUT 164U 1780 09' 08-Feb-OO Ch~hil~ 0~~8dfi Dfi~ RF-OUT-I 1646 1480 rrvi C)i,feb.00 Coiiiunt,, t~i't~I MPN RJ=.,jN 1646 1000 t#iOOml OQ.feb-00 -83400 ca,~,-~ff.-11 f~1;,i:.cJ Mf'i-4 I-cf-OUT 1MB 1EJO,OOO 100 ml 08Feb-OO CU1Hoar1, F~Oti~ MPi~ RF.OUT-I 1848 S0,000 iiOO rnl 08~ i'tliit·lil~ wad l\iiiiriw ~-IN 16'6 0.06 mg/I 09-Feb-00 0.036 Nltrc.w iiiw f..Uui~ kf.Our 1648 0.04 mg/I -~.ao Nltl.a~ liil''lll Niiri~ RF-OUi~.f 1848 0,01 • OQ.f'..00 IIJiiu.,~~r,, 1'git.J Kj~ FcF•lN 104G 24.3 mr;, Oa.Feb-00 13.66 Niif~i;,,i'11 ~fo~ K~iQii.M RF-OUT 1646 10.4 n}WI O&-feb-00 Ni~;-"~'11'1, leikd Kji:;IdiiJ'll RF-OUT-I 1646 11.1 man Oi-Feb-00 Oll ~flQ C:il't;,~l;j RF•IN 1&4tl ~-n)QII OQ.Feb.QO 283 h,Hi.lQl1t l1wiU0Val etnciencic:a aver~ about SO% for all ~ te5ied. The minimal RWOvaJ was 3,¾ fo1· ~ illd the ma.wnum removal was 74% ur SUipCilded Solidi. Colliuiu, b11Cuma were oot ~vely removed by the skimmer ~ aitbou&b, they are not deiisned to vnrvJoe ~ dJEhMon. Oil and ~ are a food &01.lAie for bacicria and ~ of tJUs pollutant blt~ld provide BOl® d&ct on ~ IUIDlben. 37% •