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CT 05-06; CASSIA PROFESSIONAL OFFICES; STORM WATER MANAGEMENT PLAN; 2005-02-02
'. • o4-/l(ll -S STORM WATER MANAGEMENT PLAN For CASSIA ST. PROFESSIONAL OFFICES Thomas L. Guinn Revised: March 14, 2006 Revised: January 31, 2006 Prepared: February 2, 2005 IN 04-1109 Prepared By: O'DAY CONSULTANTS 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92008 RCE 69017 Date 6/30/06 r • 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 ............................................... .4 2.1 Soil Characteristics ............................................................................................ 4 2.2 Potential Discharges ........................................................................................... 5 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY ........................ 5 3.1 Site Design BMP's ............................................................................................. 5 J 3.2 Source Control BMP's ....................................................................................... 6 3.3 Individual Priority Project Categories ............................................................... 6 3.4 Treatment Control BMP's .................................................................................. 6 3.5 Construction BMPs .................................................... : ....................................... 7 4.0 MONITORING, INSPECTION, AND REPORTING ............................................ 7 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 WaterBMP Requirements Matrix 6. Table 3: Numeric Sizing Treatment Standards 7. Project site plan & BMP map 8. Site Design BMPs 9. Source Control BMPs 10. Treatment Control BMPs 11. BMP Sizing Calculations '. 12. Post Construction BMPs Maintenance Cost Responsibilities • • • STORM WATER MANAGEMENT PLAN Federal, state and local agencies have established goals and objectives for storm water quality in the region. The proposed project, prior to the start of construction activities, 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 Tentative Parcel Map. 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 The Cassia Professional Offices are proposed in the City of Carlsbad at the intersection of El Camino Real and Cassia St. (see Vicinity Map, attachment 1). The site is to be divided into one open space lot, and two office-use lots. El Camino Real is to be improved to prime arterial classification requiring the construction of a significant portion of embankment within the open space parcel. Cassia St. is to be constructed in conjunction with SDP 02-13 along the southerly subdivision boundary line. 1.1 Hydrologic Unit Contribution The project is located in the Batiquitos Hydrologic Subarea (904.51) of the San Marcos Watershed in the Carlsbad Hydrologic Unit in the San,Diego Region. Under existing conditions, storm runoff flows from El Camino Real are collected and conveyed through a natural drainage course to the easterly subdivision boundary, enter a culvert flowing under a D.G. access road and discJ,1arge off site. Flows from the southerly portion of the subdivision concentrate into a separate natural drai~age course and are then conveyed easterly to the subdivision boundary, where they flow offsite across the access road and converge with flow from El Camino Real. The proposed project will not alter the drainage discharge patterns on site. Subdivision' improvement will adjust drainage basin boundaries, but in such a way as to control and mitigate increases in runoff within each basin. The increase in impervious area will be mititigated by a detention basin, landscaped swales and other control BMP's . • 1.2 Beneficial Uses • • The beneficial uses for the hydrologic unit are included in attachment 2, and the definitions are listed below. This information comes 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, swimming, 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 normally involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, picnicking, sunbathing, hiking, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjl;lnction with the above activities. 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 mammals, 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 mammals, 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 ~stablished 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 anadromous fish. BIOL -Preservation of Biological Habitats of Special Significance: Includes uses of water that support designated areas or habitats, such as established refuges, parks, sanctuaries, ecological reserves, or Areas of Special Biological Significance (ASBS), where the preservation or enhancement of natural resources requires special protection. 2.0 CHARACTERIZATION OF PROJECT RUNOFF According to the California 2002 303d list published by the RWQCB (attachment 3), San Marcos Creek HA is an impaired water body associated with the direct stormwater discharge from this project. San Marcos Creek HA has low priority impairment for Bacteria indicators. 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 by applying the following concepts (see attachment 6 for details): Development Clustering: Establishing planning areas in clusters accomplishes several desirable effects. Drainage systems service only developed areas reducing the amount of debris, siltation, and sedimentation associated with natural drainage courses. Natural drainage courses are preserved maintaining existing hydrologic regimes. Smaller basins are established with multiple distributed outlets minimizing flow concentrations Conserve Natural Areas: The natural drainage swales within the open space lot will be left in a natural, undisturbed condition. Minimize Directly Connected Impervious Areas: To the maximum extent practicable, parking lots, sidewalks, patios, roof top drains, rain gutters, and other impervious surfaces shall drain into adjacent landscaping prior to discharging to the storm water conveyance system . Protect Slopes and Channels: All runoff will be safely conveyed away from the tops of slopes. • • • Energy Dissipaters: Energy dissipaters shall be installed at the outlets of new storm drains, culverts, or >channels that enter unlined channels in accordance with applicable standards and specifications to minimize erosion. Energy dissipaters will be installed in such a way as to minimize impacts on receiving waters. Detention Basin: In order to control post -development peak storm water runoff discharge rates, flow from Cassia Road Professional Offices will enter a detention basin adjacent to EI Camino Real before flowing into an existing natural swale. 3.2 Source Control BMP's Source Control BMPs help minimize the introduction of pollutants into storrh 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 and city maintained streets will be swept routinely in order to reduce introduction of trash, debris, sediment and siltation into drainage systems. Trash Storage Areas to Reduce Pollution Introduction: 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. All trash containers shall contain attached lids that exclude rain or contain a roof or awning 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 Individual Priority Project Categories Surface Parking Areas Where landscaping is proposed in surface parking areas (both covered and uncovered), incorporate landscape areas into the drainage design. 3.4 Treatment Control BMP's 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. The project has been designed so that runoff is treated by Site Design BMP's prior to Structural Treatment BMP's. • • • Treatment control BMP's 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. A combination of vegetated swales and one inlet filter were chosen and will provide maximum pollutant removal efficiency for anticipated pollutants. The Treatment BMPs selected for each basin are discussed below and are shown on Attachment 9. Extended Detention Basin: As discussed in Section 3.1, a dry extended detention basin is being constructed on the northwestern corner of the property. This basin will provide flood control and will detain and treat runoff from the vegetated swale. Vegetated Swale: A landscaped swale will run along the western and northern sides of the property an<;l will treat surface and roof runoff. The swale will flow into the detention basin located on the northwestern comer of the property. 3.5 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 4. Storm drain inlet protection 5. Stabilized construction entrance/exit 6. Vehicle and equipment mainte.p.ance, 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 recor<;led on the included checklists (see next page). The Owner and Developer will be responsible for the· monitoring and maintenance of the BMPs . • DATE WEATHER i:\Accts\021040\BMP CHECKLIST.doc .'. -~ . . ( , BMPCHECKL • (TO BE COMPLETED WEEKLY) ---• INADEQUATE BMPs CORRECTIVE ACTION OBSERVATIONS • CITY OF OCEANSIDE . or- I NOT TO SCALE o~ •• L· CITY OF ENCINITAS VICINITY . . l.~/~ £4STA ROAD: SITE I~~ '.' CITY OF SAN MARCOS r . . . "'== MAP .-'~ ~.,',' Table .2. BENEFICIAL USES OF IN~~URFACE WATERS .~.., -. ----------- BENEFICIAL USE inland Surface Waters 1.2 Hydrologic 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 ~ A f Number N R 0 0 R. S W C C 0 R l Il. R W C H 1 2 l M 0 0 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 Watershed San Marcos Creek 4.51 + • • • • • Encinitas Creek 4.51 + • • • • • . 1 Waterbodies are liited multiple times if they cross hydrologic area or sub area boundaries. • Exis~ng Beneficial Use o Potential Beneficial Use 2 Beneficial use d~ignations apply to all tributaries to the indicated waterbody, ifno; listed sepilU'Ia'i:e!lf. + Excepted From MUN (See Text) Table 2·2 BENEFICIAL USES 2-27 September~. ~ ®®4 J \ . Table A. BENEFICIAL USES OF CO~S~l 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 6 T L 1 2 M L D Pacific Ocean • • • • • • • Dana Point I-larbor • • • • • • 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 • • • • • Lo~ Penasquitos Lagoon 2 6.10 • • • • • San Dieguito Lagoon 5.11 • • • • • Batiquitos !-agoon 4.51 • • • • • San Elijo lagoon 5.61 • • • • • Aqua Hedionda Lagoon 4.31 • • • • • • Includes the tidal prisms of the Otav and Sweetwater Rivers. 2 Fishing from shore or boat permitted, but other water contact recreational CREC-l) uses are protlibited. • Existing Beneficial Use Table 2-3 BENEFICIAL USES 2-47 ,,..--.,. ..... -' • R M A M S W S A A Q ~ P A H 'R R U G W R IE' E A R N M L I l • • • • • ~ • • • • ~ , • • • • @ • • • ® • • • • @ • • • @ • • • ~ • • • ~ • • • @J • • • • • • • • • • • • • (;l - - , SePtember 8, 1 ~94 9 c ,~UJ:" ~ VV A ~~LTION 303(d) LIST OF WAJ.-ii<·~~ALITY LIMITED SEGMENT SAN DIEGO REGIONAL WATERQU~NTROL BOARD Pacilic Ocean SboreliDe, San Diequito BU 90511000 Baeteria IDdieators Low 0.86 Miles /mpainnenI1ocoted at San Die.guilo Lagoon MDIIIh; So/QIIQ Beach. ,.jpprol·ed hYi/SI .• JII~I' 10 NonpointlPoiat SolU'Ce ~~~~::'~i··:,~.';"4"~"'T'" ~""ii'i"M"H,ng:p;;t'A;r-5fHY;-'11""$'lQ*f5;!liitif3Q .. e..iV355iW$¥ fj5¥¥~*t Gtd 56'& dl2i%WdiiR'i' 'd' e" CR'iSHirf w;rwF#S"33'&';;\iI"''S;''OVW7Vli}!'t.&''~~:#~·~~·e'i.M~·_~-~~~·. 9 c Pacific Ocean Shoreline, San Joaquin BiDs BSA 90111000 Bacteria mdieators Low 0.63 Miles Impairment located at Cameo Cove at Irvine Cove Dr ./Riviera Way. Heisler Park-North Urbao RunotJIStorm Sewers Unknown Nonpoint Source Unknown point source .:.:;..,_,~.w:.~~,}.,.t.....;""; ' .. :;.-'m"''; ~w;-"N,·,-?J:@jjjAi;'ji.;t" .... ,g.:;1j1~iNr$Itp..rmf£F'ifi'ii'iiS'Y:im:S'R'C5Nttri&?3*,&·$th$ hSMi t f E"i'&# iF dee" §tlni%r~~~~~~~~~~~.;.,;:..;:::·:··, .-' ~., 9 C !"acilic Ocean Shoreline, Sao Luis Rey au 90311000 Bacteria Indieators Low 0.49 Mi&es lmpairmenllocated at &m Luis Bey River Mouth. NonpointJPoint Souree --_" ;' """:. ..... ..\:t~:!j.:;;;, <pi"!;;;' 'Mere-;m·1ins;r,jb.,;y_"i'~.~~~'fE'if5'2l1iifSrzcm=rsm·f '.;,i&'9S'5*i'%i'dlrri • '·*i'.u..~n~~~~~~~l1~~,:,.r"'~~~;:"1 !) C Paeific Oceau Shoreline, Sao Mareos BA 90451000 Bacteria lDdieators Low 0.5 Miles Impairment /ocated at Moon/ighl State Beach. :~'ie';'S' '. m'"~';" ~'''I')' ·o},,_; .. 'I ;. J .M!i}":ffAASf' ... a'diiii&jfgtN..-s:ag'W,:r;W .... PhiSb'to/iPA'BW.c:m5iMf1t ~W ~ NonpoiDtlPoiat Source 9 C PacifieOeeauShoreline,SerippsHA 90630000 ~s UIlW&6t1M .. """" ! '!!!II W *"*"""".I!!!f"'~'!,ilj!!!,...~=·,~,~.,!l~;,.%;;"'"~~~",:;,·""". Bacteria Indicators Medium 3.9 Miles Impairment located at LrJ.JoUa Shores Beach at Hi PaslO Grande. La Joikl Shores Beach at Caminito Del Oro. l.a Julia Shores Beach at Vallecitos, LrJ. Jolla Shores Beach at Ave de kl Playa. Casa Beach (Chilt:irem Pool). 80mh Casa Beach at Coast Blvd.. Whispering Sands Beach at Rmlina St., Wmdan.sea BlUlCh at Yista de la PIQ)'a, Wmdansea Beach al Bonair Sf .. W'mdansea Beach at Playa del Norte. W'ouIansea Beach at Palomtll' Ave.. Tourmaline Surf' Park, PaciflC Beach af Orand be . • r. •••.• ~ .. a .... V~~~ ...... ..,;..;O;\ ..... l ... ...:-::;.>b,J ....... ll .. *rl .... e;ws .. 't:'1%~sW?*m%w+-mmr"t'Ai2:=mrmrnarwJ.,=v t.~ODpoiat!!.oiD.t Soarce 9 C Pacifie Ocean Shoreline, Tijuana HU 91111000 G ;n"''''''ffi''tlIlf!t 'i"!lI'!j!fIfj'fII1l!i!§51'~~"".'W>':;~~,=f="'i Baeteria Indicators Low 3 Miles Impairment locatedfrom the border. ({JI:tending north along the shore. Nonpoint/Point Source _...::-z~ ... l.t,> plt ",-,j~)' "h~ ·o::.\j..N.htl:=Mf'i1.4G.W~..t~ ... i''1tt1V''',a;r;tBf§'£r1f'i&>fAm=f;!Pi'ftfF?fj tM#i!~'PiiHiS 1TEKWW Flitr=C2?enrwefflnr.m.;;;~mi'W@i'iID'~r~:l!iea~et~~~,!W:.1v.~>.!l:l:$. 9 R Pine Valley Creek (Up~r) 91141UUV Eutel'OeliW Medium Grazing-Related Sources Coneentratcd ADimal Feeding OperatiollS (pennitted, point source) 1.9 Miles Trausieat eaeamp~ts ,£ , i'N M".W.ili~Il •• ll::a:.l.*;:!!l.I?~iSi!>.\l,ll'.lli;a\\\-:!ll~~ • ..:.""""'~<. ~~~~~~~~~~~~~~~·~~~~~~~~··~w_·~~75WR$~~~.,.~~~·=e~UP9n~~5$~S%Fffi~~wor~sfW1WRSV~~~~ag~Ufmf~.~tg.~~~;;;; .. i;;aag;a .. ~aa"QI~~~5C~~~~W ~ .... '" b ... i ... ,. .. ,g.·-w.B·~ ... !:;.§;'··~i~:I;;'i..,'&'1:":eiJiS=4iTIF.,M*ii A5t Pflge7o/16 •• ( i • ~~@Ii'/l'f{jJ W~ft®rr $t~Wll~~Ii'<d1~ 4103/03 When referred to this Section. by Step 2 of Section II, complete the analysis required for your project in the subsections of Section 111.1 below. 1. IDENTIFY POLLUTANTS & CONDITIONS OF CONCERN A. Identify Pollutants from the Project Area Using Table 1, identify the project's anticipated pollutants. Pollutants associated with· any hazardous material sites that have been remediated or are not threatened by the proposed project are not considered a pollutant of concern. Projects meeting the definition of more than one project category shall identify all general pollutant categories that apply. Table 2. Anticipated and Potential Pollutants Generated by Land Use Type. General Pollutant Cateaor/es Project Trash OXygen Bacteria Categories Heavy Organic & Demanding Oil & & Sediments Nutrients Metals ComDounds Debris Substances Grease Viruses Pesticides Detached Residential X X X X X X X Development Attached Residential X X X Pll) P(2) pm X Development Commercial Development Pll) pm P(2) X P(5) X pIa) P(5) >100,000 ft2 Automotive X XI41(5) X X Repair Restaurants X X X X Hillside Development X X X X X X >5,000 ft2 Parking lots P(1) PII) X X pm X PII) Streets, Highways & X Pll))( X X(4) X P(5) X Freeways X = anticipated P = potential (1) A potential pollutant If landscaping exists on-sita. (2) Apotential pollutant if the project includes uncovered parking areas . (3) A potential pol1utant if land use involves food or animal waste products. (4) Including petroleum hydrocarbons. li51lncluding solvents. • • ~t@tr:m W®t@fi' ~t~ffil(\)~~Il'©'l~ 4/03/03 s 'fable i. ~iandard DS'\fe~@fIlmefi"il2 f!'w@js©t& Pffl@riw Project i;orm W t BMPR equlrements a er BMPs Applicable to Ind/vldual Priority Project Categorles(3} aa fI) j In I II) fG' III ,~ 5: ~ J 8» ~ ,~ .c 'm c-III : § OJ J II) c8» CD .c I j -a J ~ J: lIS ~~ j ,I ~ &! a;. Q)a. g ~ ~ CD -a-' i! :!i! II) M atrux. f i ~ '81 ~ j ~ ~ Site Source M ::J a Treatment, Q. rx::(!) .:> 0 U) u.. ::t: Design Control ai .ci d -d cD c:b .c Control BMPsl') BMPs(2) ...: ,-'-, BMPslIJ Standard Projects R R 0 0 0 0 0 0 0 0 0 0 0 PrIorIty Projects: Detached ResIdential R R R R R S Development Attached ResIdential R R R S Development Commercial Development R R R R R R S >10000012 Automotive Repair Shop R R R R R R R S Restaurants R R R R S Hillside Development >5 000 ftZ R' R R R S Parking Lots R R RCB) S Streets, Highways & R R S Freeways R = RequIred; select one or more applicable and appropriate BMPs from the applicable steps In Section 1II.2.A-D, or equivalent as Identified In Appendix C. o = OptionaV or may be required by City staff. As appropriate, applicants are encouraged to Incorporate treabnent control BMPs and aMPs applicable to individual priority project categories Into the project design. City staff may require one or more of these BMPs, where appropriate. S = Select one or more applicable and appropriate treatment control BMPs from Appendix C. (1) Refer to Section 1II,2.A. (2) Refer to Section III.2.B. (3) Priority project categories must apply specific storm water BMP requirements, where applicable. Priority projects are subject to the requirements of all priority project categories that apply. (4) Refer to Section 111.2.0. . (5) Applies If the paved area totals >5,000 square feet or with >15 parking spaces and is_ p_otenlla/l~ exposed to urban runoff • r". • I \ ~a@ffm W~~@!f ~ft~lrIldl~tr©l@ 4/@31O'Jl Volume 1. Volume-based BMPs shall be designed to mitigate (Infiltrate. filter. or treat) the vofume of runoff produced from a 24QI'!our 85111 percentile storm event, as determined from. rsopluvla' maps. contained In the County of San DIego Hydrology Manual. Flow .. 2. Flow-based SUPs shall be designed to mitigate (Infiltrate, filter, or treat) the maximum flow rate ot runoff produced from a rslnlaH Intensity of 0.2 Inch of rainfall per hour lor each hour of a storm ~~t . I. Struptural Treatmant BMP Selection Procedure " riority projects shall select a single or combination of treatment BMPs from the ,. (' I egorJes In Table 4 that maximize pollutant removal for the particular pollutant(s) ot ", "'If ncern. A ny pollutants the project I s a xpected tog enerate t hat a re a Iso causing. a ---Clean Water Act section 303(d) Impairm~nt of the downstream receivIng waters of the project should be given top priority in selecting treatment BMPs. . , To select a structural 'treatment BMP using 'the Structural Treatment Control BMP Sel~ctlon Matrfx (Table 4). each priority project shall compare the list of pollutants for. which t"e downstr~am receiving waters are impaired (If any)." According to the 1998 303(d) "sting. the Agua Hedlonda Lagoon is Impaired for sediment and siltation. Buena Vista Lagoon also has impaired beneficial uses (aquatic life) due to high sedlm~~tatlonlsiltatlon. Portions of Carlsbad where construction sites have the potential to d iscillarge into a tributary 0 fa 303(d) 0 r directly I nto a 3 03(d) water body or sites located1withln 200 feet of an ESA require additional BMP implementation. These water bodies Include the Pacific Ocean. Buena Vista Lagoon. Encinas Creek. Agua Hedionda Lagoo~, and Batlquitos Lagoon. Priority projects that are not anticipated to g~nerate a pollutant for which the receiving water is Clean Water Act Section 303(d) impaired shall select a single or combination ,of structural treatment BMPs from Table 4 that are effective for pollutant removal of the identifi~d pollutants of concern determined to be most significant for the 'project. Selected BMPs must be effective for the widest range of pollutants of concern anticipated to be generated by a priority project (as identified in Table 1). '.rnativa storm water BMPs not identified in Table 4 may be approved at the , discretion of the City Engineer, provided the alternative 8MP is as effective in removal of pollutants of concern as other feasible BMPs listed in Table 4. " • '. '. ~~~t~@rru ~ ~@ttIl~~~ «;@[fQ~~@~ ~~~~ 40 1 !fitr@d(UJ~tB@1n) This section describes specific source control Best Management Practices (BMPs) to be considered for incorporation into newly developed public and private infrasiTucture, as well as retrofit into existing facilities to meet stormwater management objectives. 'ir@l IbJfi~ ~= 1L ~@IWj"«::® (b:@!l'iltl:Ii@~ rBlfi\lil[!:l>§l If@1l" Source control fact sheets for design are listed in Table 4-1. The fact sheets detail planning methods and concepts that should be taken into consideration by developers during project design. The fact sheets are arranged in three categories: those that have to do with landscape, irrigation, and signage considerations; those that have to do with use of particular materials, those that hav~ to do with design of particular areas. Fact Sheet Format A BMP fact sheet is a short document that provides information about a particular EMP. Typically each fact sheet contains the information outlined in Figure 4-1. Supplemental information is provided if it is available. The fact sheets also contain side bar presentations with information on BMP design objectives. Completed fact sheets for each of the above activities are provided in Section 4-4. lDesigfiil Design SD-I0 Site Design and Landscape Planning SD-ll Roof Runoff Controls SD-12 Efficient Irrigation SD-13 Storm Drain System Signs Materials SD-20 Pervious Pavements SD-21 Alternative Building Materials Areas SD-30 Fueling Areas SD-31 Maintenance Bays and Docks SD-32 Trash Enclosures SD-33 Vehicle Washing Areas SD-34 Outdoor Material Storage Areas SD-35 Outdoor Work Areas SD-36 Outdoor Processing Areas BMP Fact She'ets Description of the BMP Approach Suitable Applications Design Considerations o Designing New Installations Source Control BMP Fact Sheets for design follow. The BMP fact sheets are individually page numbered and are suitable for photocopying and inclusion in stormwater quality management plans. Fresh copies of the fact sheets can be individually downloaded from the California Stormwater BMP Handbook website at [l Redeveloping Existing Installations fumplemental Information -www.cabmphandbooks.com. r I!l Examples eI Other Resour<;es '1 January 2003 fJSH~IlJlIl"~ 4=1L ~~@Iiilil!PlU@ fJS@~tl: §;!hl@®1t California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbool<s.com 4-1 • • • if" Ma)(imize Infiltration ,f Provide Retention '" Slow Runoff Minimize Impervious ~and Coverage Pr()hibit Dumping of Improper Materials 1lJl~~(f;rH ptth;~!l'B Contain Pollutants Collect and Convey Irrigation water provided to landscaped areas may result in excess irrigation water being conveyed into stormwater drainage systems. A~pr©~te~ Project plan designs for development and redevelopment should include application methods of irrigation water that minimize runoff of excess irrigation water into the stormwater conveyance system. §IlJ]B\t~bfl~ A~IPlUQ«:@.lttH@Ii'il~ Appropriate applications include residential, commercial and industrial areas planned for deyelopment or redevelopment. (Detached residential si~gle-family homes are typically excluded from this requirement.) 1!Jl@l~Dg!l'ft ~@tlil~n@.l~liattfi@li'II~ J/)esig7J7J.i7J7J.g New ][7J7J.sttlfJ1~llfJ1tJi([p7l1l.s The following methods to reduce excessive irrigation runoff should be considered, and incorporated and implemented where determined applicable and feasible by the Permittee: BI Employ rain-triggered shu.toff devices to prevent irrigation after precipitl;ltion. [J Design irrigation systems to each landscape area's specific water requirements. Include design featuring flow reducers or shutoff valves triggered by a pressure drop to control water loss in the event of broken sprinlder heads or lines. Implement landscape plans consistent with County or City water conservation resolutions, which may include provision of water sensors, programmable irrigation times (for sh.ort cycles), etc . January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 1 of 2 • Design timing and applicatilOn met-hlOds IOf irrigatilOn water tlO minimize the runlOff Df excess irrigatilOn water intlO the stlOnn water dI!.'ainage system. Group plants with similar water requirements in Drder tlO reduce excess irrigatilOn runlOff and prlOmDte sm:face filtratilOn. Choose plants with llOw irrigatiDn requirements (flOr example, native lOr drought tlOlerant species). ClOnsider design features such as: Using mulches (such as wlOlOd chips lOr bar) in planter areas withlOut ground clOver tD minimize sediment in runDff Installing apprDpliate plant materials fDr the location, in acclOrdance with amounf of sunlight and climate, and lUse native plant materials where possible and/or as recommended by the landscape architect Leaving a vegetative barder along the properry boundary and interior watercourses, tlO act as a pollutant filter, where appropriate and feasible Choosing plants that minimize or eliminate the use of fertilizer or pesticides tD sustain grDwth Gl Employ othe.r cDmparable, equally effective methlOds tD reduce irrigatiDn water runoff. R<erdL<eTJJ<eU([]/[P/ll.T!1l@ JE-J.d2ttll.T!1l@ JlTrv.sti(QlUO(fJ1ttll.(})7TV.$ t iDUS jurisdictiDnal stmmwater management and mitigation plans (SUSMP, WQMP, etc.) ne "redeveIDpment" in terms Df amDunts Df additional impervious area, increases in gross DDr area a~d/ Dr exteriDr clOnstructiDn, and land disturbing l:!.ctiviti:es with structural Dr impervious surfaces. The definition Df" redevelDpment" must be cDnsulted tD determine whether or nDt the requirements fDr new develQpment apply to areas intended for redevelopment. If the definitiDn applies, the steps Dutlined under "designing new installations" above should be fDllowed. . @ttlhl®l!" 1lt~§l@I!'!Hr~®~ A Manual fDr the Standard Urban StDrmwater MitigatiQn Plan (SUSMP), LDS Angeles CDmity Department of Public Works, May 210102. Model Standard Urban StDrm Water MitigatiDn Plan (SUSMP) fDr San DiegD CQunty, PQrt Df San DiegQ, and Cities in San DiegQ CDunty, February 14, 210102. MDdel Water Quality Management Plan (WQMP) fDr CDunty Qf Orange, Orange CDunty Flood CDntrol District, and the IncDrplOrated Cities Df Orange CDunty, Draft February 210103. Ventura CQuntywide Technical Guidance Manu2IJ fDr Stormwater Quality CQntrDI Measures, July 20102 . • 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbool<s.com • • • ~[~(g)rrrlli' Dffi~@j~lfU ~B~Bl~~~ j" .... _ ~ 0' .. ,_,_ F-"'-"'--.""" __ ."_,....._~--.-~ --... ~ .... ,_ .. ""'._ .... ,_, ....... ".,. ............. ·....,., ..... u._,.,_ .......... ,..-.".,,..._ 'm-....-' ... '-_.',~~.....""", , __ , ~.J" ____ ' .... _ • ..,.."',,-' _"""' .. ,~ ... """-•• _"".,~_ .. ""'<~,> .. _ f!)~~te:ru DJltB ©lIi'iI Ma)(imize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage . J Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey ====~~====~~======== Waste materials dumped into storm drain inlets can have severe impacts on receiving and ground waters. Posting notices regarding discharge prohibitions ~t storm drain inlets can prevent waste dumping. Stonn drain signs and stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets. ~L~1P'[j"@@)«::[tu The stencil or affixed sign contains a brief statement that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain messages have become a popular method of alerting the public about the effects of and the prohibitions against waste disposal. ~Mnt~flj)~@l A~1P'nB«::@lttH@IIil~ Stencils and signs alert the public to the destination of pollutants discharged to the storm drain. Signs are appropriate in residential, commercial, and industrial areas, as well as ,any other area where contributions or dumping to storm drains is likely. [}~§lHgll'il ~@Iill~g@l~[f'@lttB@Ii'il~ Storm drain message markers or placards are recommended at all storm drain inlets within the boundary of a development project. The marker should be placed in clear sight facing toward anyone approaching the inlet from either side. All storm drain inlet locations should be identified on the development site map. jJJ)®~#'@Tf&.v.Tf&.@ New ][Tf9.31J:([J1UU([J1tJi([j)Tf&.~ The following methods should be considered for inclusion in the project design and show on project plans: G Provide stenciling or labeling of all storm drain inlets and catch basins, constructed or modified, within the project area with prohibitive language. Examples include "NO DUMPING - January 2003 California Storm water BMP Handbook New Development and Redevelopment www.cabmphandbooks.com $1!:@0'llii!l\'Mc\il!l;@0' @f!IlaJU~ ~@~ilOiJlt;il@1iiJ 1 of:2 ~ r;cy = ~ ?~ ~ q.ZJr,R~ rn:fir."\~ f\~ fTl?l ~ If?0 ~ Q @ 17fl;'l71 tfD ~ ~ /1ki.J db ~ ~ \1b'Q,CJ ~ I'd fij 1:1 IY I'J @ IHn] ~ [J gJ j;J Id @.J ~J \9 j ~"''''' .~ .. ____ ~~ ___ ~ .e, ... ~_, _. _''''.'' ""',', <A ,. > .~,' _ ~_'", ,.,_ ,,_'"=<_~, . ~_ ,_~,. " ~, __ .-... , __ <",~ ..... ~ ".....", ~. -__ ~ __ .~,.. ... '" _ • ~_,_. ~ _~.::::; _ '..... __ "" __ .= __ . ~._.""",,_ ....--A_'~_ ,,-, .... , ........ , ... ,~...,_,, ___ • 0-" .'~. ,,~ __ , .~-, ... ,.. .>, • DP~NS TO OCEiL1\f" and/or other graphical icons to discourage megal dumping. EJ Post signs 'With prohibitive language and/or graphical icons, which prohibit megal dumping at public access points 21Jong channels and creeks vvithin the project area. Note -Some local agencies have approved specific signage and/or stor:m drain message placards for use. Consult loc2l1 agency stonnwater sb:lff to determine specific requirements for placard types and methods of application. R~rff1~'&J~H(nr[[pi:D'V.@ lEJtR.srfJi7JO.@ JITi11£(J;iJJ1HH@:(fi([J/lfiliiJ Variousjurisructional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in tenns of amounts of additional :impervious area, increases in gross floor area andlor exterior construction, and land disturbing activities with Shl1ctural or impervious surfaces. If the project :meets the definition of "redevelopment", then the requirements stated under" designing new installations" above should be included in aU project design plans. £&.©l©lD'itD@Ifil@D Jruotr@UOIITl'il@ttu@1fil M iJJ1i7l1l1t~7l1liJJ17l1liC<e C@7J1Ul)irff1~Tf'([lltliffJY1J1U~ G Legibility of plarkers and signs should be maintained. If required by the agency with junsdktion over the project, the owner/operator or homeowner's association should enter into a maintenance agreement 'With the agency or record a deed restriction upon the • property title to maintain the legibility of placards or signs. JlDHiJJ1c~m<e7JO.tl E'J §ignage on top of curbs tends to weather md fade. [J §ignage on face of curbs tends to be worn by contact with vehicle tires and sweeper brooms. ~Q,[IJPlJPlH®IITI'il®lfiltt@a lrlfilff@ff'!lil'il@l'll:H@1fil ]E-Jmmpi«e$ El Most MS4 programs have storm drain signage programs. Some MS4 programs -will provide stencils, or arrange for volunteers to stencil storm drains as part of their outreach program. @ttll'il®lf' ~®~@Q,[Ifi"~®!§j 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. Ventu.ra Countywide Technical Guid<:lJ:lce Manual for Stormwater Qualit-y Control Measures, July 2002 . • 2 of 2 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • !Ql®~cglj~D [p)ltu©u'll Trash storage areas are areas where a trash receptacle (s) are located for use as a repository for solid wastes. Stormwater runoff from areas where trash is stored or disposed of can be polluted. In addition, loose trash and debris can be easily transported by water or wind into nearby storm drain inlets, channels, and/or creeks. Waste handling operations that may be sources of stormwater pollution include dumpsters, litter control, and waste piles. A~I,QlIi"©al~!hJ This fact sheet contains details on the specific measures required to prevent or reduce pollutants in stormwater runoff associated with trash storage and handling. Preventative measures including enclosures, containment structures, and impervious pavements to mitigate spills, should be used to reduce the likelihood of contamination. ~illloit©l~~® A~[;Ql~flcgWJfl:U©Ii1l~ [Q)@~O@J uil (Q)1b>]~«;\l:fil)U@§i Maximize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials J Contain Pollutants Collect and Convey Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) [Q)~~9@1l'il «:©[i"il~D@]®fl"WJitfl@[i"il~ Design requirements for waste handling areas are governed .by Building and Fire Codes, and by current local agency ordinances and zoning requirements. The design criteria described in this fact sheet are meant to enhance and be consistent with these code and ordinance requirements. Hazar¢l.ous waste should be handled in accordance with legrul'equirements established in Title 22, California Code of Regulation. Wastes from commercial and industrial sites are typically hauled by either public or commercial carriers that may have design or access requirements for waste storage areas. The design critelia in this fact sheet are recommendations and are not intended to be in conflict with requirements established by the waste hauler. The waste hauler should be contacted prior to the design of your site trash collection areas. Conflicts or issues should be discussed with the local agency. If)1Z~P.rg;7ro.P'7ro.rg; NIZW J[~tJ:QJJ..HHQJJ..ttii([})7ro.~ Trash storage areas should be designed to consider the following structural or treatment control BMPs: G Design trash container areas so that drainage from adjoining roofs and pavement is diverted around the area(s) to avoid run-on. This might include berming or grading the waste handling area to prevent run-on of stormwater. !ill Make sure trash container areas are screened or walled to ff . r h prevent 0 '-slte transport or tras . January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmpi1andbooks.com 1 of 2 ~D=~d2 I, ,,"," . ___ •• ..,. "",'~""" -~ ... p 'v·, ,. . ......... , • ." .,', ,,"_,,~, ~ ..... ~~_, _ ....... _~ _ .••. ~ .... ,._ ~_~ ••• ,_ , -_. -... " "~_'~ ~_ -_.-._. -__ • _, ~" ..-,_ 4.,....., ... "."' ..... " ..... ..,.~ _._" ,~ .. ~,. _,_ , __ ~ __ ~"", -_ ,~"""'_",,"'" • ..,~....-~~'~T~'_ --.~~,.., ......... _ ... ,~_ j • Use lined bins or dumpsters to reduce leaking ofliquid waste. o Provide roofs, awnings, or attached lids on all trash containers to IDinhnize direct precipitation and prevent rainfall from entering containers. EJ Pave trash storage areas with an impervious smface to mitigate spills. 121 Do not locate storm drains in immediate vicinity of the trash storage area. o Post signs on all dumpsters informing users that hazardous materials are not to be disposed of therein. Rrzrdlrz1lJrza@pRTI11.@ lED§f'1iTl11.@ IbTll.§fi:@aa@f'1i@7fi!.§ Various 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 installafion~" above should be followed. ~©I<6!18ttB@Gil~n JIli'iliF@Irm@1tn@1i'il M([f1R7Til.ttrzTl11.@7Til.~rz C@7fi!.§idlrz1l"@f'1i@7Til.§ ~e integrity of structural elements that are subject to damage (i.e., screens, covers, and signs) must be maintained by the owner/operator. Maintenance agreements between the local agency and the owner/operator may be required. Some agencies will require maintenance deed restrictions to be recorded of the property title. If required by the local agency, maintenance agreements or deed restrictions must be executed by the owner/operator before improvement plans are approved. ~t6'n~1l" 1R~$@I!JlIl'~cew 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 Measures, July 2002 . • I" .," 2 of 2 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandboo!(s.com January 2003 • • • ~@j 8~~~ ~1l~ I ~'fc(Q9r@~~ ~B~~@;J 5~?lLm @ D1~~Hld@ wl1(c~ t· .. ". ___ " _,--,_,"" ___ ' __ "'~~ ___ '_~'""' ____ :;""-~ __ .,. ~ .. "'<_ ... ..."..,~~"' __ ~",J_".~,." .... _~ ~ ___ -~ ~_'"" __ ,._.~ ... __ ,-, __ ~.,.r-_ , ____ ~_.< .. __ j ••• ,, __ ........... ~y~~_ .. ,_ ... .-<r [)~~(!lf'iptH@ti1I Parking lots and storage areas can contribute a number of substances, such as trash, suspended solids, hydrocarbons, oil and grease, and heavy metals that can enter receiving waters through stormwater runoff or non-stOrnlwater discharges. The .following protocols are intended to prevent or reduce the discharge of pollutants from parking/storage areas and include using good hOUlsekeeping practices, following appropriate cleaning JBMPs, and training employees. ARJlpr@~~1lil P@!!u.n@1J'§. PtJoelJJ~1l1J.tti@7JT1. ['J Encourage alternative designs and maintenance strategies for impervious parking lots. (See New Development and Redevelopment JBMP Handbook). ill Keep accurate maintenance logs to evaluate JBMP implementation. §1JJl@gelf3ttelJ!1 IPIPIfPtJ;IfPCT;IfPT/2 General EI Keep the parking and storage areas clean and orderly. Remove debris in a timely fashion. EJ Allow sheet runoff to flow into biofllters (vegetated strip and swale) and/or infiltration devices . o Utilize sand filtel'S or oleophilic collectors for oily waste in low concentrations. January 2003 California Stormwater BMP Handbook Municipal www.cabmpl1andbooks.com ',.> •••• ~ ...................... ";.. .:.. •• __ "'I._~._.'.!.. __ .......... _.::.. ...... ·_ .. n __ ._-:.:.·.~.· •• •• El Cover El Contain El Educate EJ Reduce/Minimize o Product Substitution li~fi~~~U:®©'J ~@Iiil~il:fifJ;(!'!]®Iiilt!:~ c; or -.-. -.- Sediment ,f NutrientsJ Trash Metals Bacteria Oil and Grease Organics O)(ygen Demanding ~[j'filiilWeil~®[j' @M.r,)U~!liV ~$@I5IJG-:lIi'U@fril 1 of 4- ~(C=@J~ ~@~~[k{~m1l~!~t@[f@g~ Ar~@ ~@8B1fb~~1l@ffi1J«:~ !~" _~ "-_ .... <~;;:;x ~_~~_> ....... ___ • ~. -...,, ___ ._, ... ~_, •• ~~._. ___ """,. _ .,....._~_'" ~~, ,. 'w, ~.h,,~,.,_ "_. ~ _~ .. ",.." ...... _ .... ~...,." ....... '.-;" _ ~~._ .. .,.' ...... ~-_r=-...... _ ....................... ~,.. <"" _'"_' ___ ~,,, ..... ,,,.., _ ~ ..... ~ ,v._ "e<--......... ' I • Arrange rooftop drains to prevent drain841e directly onto paved surfaces. o Design lot to include semi-permeable h2lJrdscape. Cont-rolling Litte'r IB Post "No Littering" signs and enforce anti-litter laws. @] Provide an adequate number of litter receptacles. [iJ Clean out and cover litter receptacles frequently to prevent spillage. o Provide trash receptacles in parking lots to discourage Utter. I:J Routinely sweep, shovel and dispose of litter in the trash. Surface cleaning EI Use dry cleaning methods (e.g. sweeping or vacuuming) to prevent the discharge of pollutants into the stormwater conveyance system. [] Establish frequency of public parking lot sweeping based on usage and field observations of waste accumulation . • Sweep all parldng lots at least once before the onset of the wet season. WI If water is used follow the procedures below: Blode the storm drain or contain runoff. Wash water should be collected and pumped to the sanitary sewer' or discharged to a pervious surface, do not allow wash water to enter storm drains. Dispose of parldng lot sweeping debris and dirt at a landfill. EI When cleaning heavy oily deposits: Use absorbent materials on oily spots prior to sweeping or washing. Dispose of used absorbents appropriately. Surface Repair E'l Pre-heat, transfer or load hot bituminous material away from storm drain inlets. o Apply concrete, asphalt, and seal coat during dry weather to prevent contamination form contacting stormwater runoff. o Cover and seal nearby storm drain inlets (with waterproof material or mesh) and manholes • before applying seal coat, slurry seal, etc., where applicable. Leave covers in place until job is complete and until aU water flom emullsified oil seal2lJ1ts has drained or evaporated. Clean any debris frorn tlllese covered manholes and drains for proper disposal. 2 of 4, Califomia Stormwater BMP Handbook Municipal www.cabl11phandbool<s.col1..1 January 2003 • • • EW@l~D~Qtru~!~t(9HJ:8@~~ 8t[J9~@J ~~BB1l1t~WB@~~® ~(C=~~ j~:( _ ~ _ ... _. _~._~, .... ~::t ~ ___ fl • .--, ._-~-_~ __ .. ",~_...,. .... __ ..... ___ ,_· .. __ "t~hL-.......... __ ~._~" •• _.' ___ 'h<_' ___ -• .;_"'_~_~_""~ __ ' -~ __ , ____ , ___ -",,_ -.~.,_ • ...,..,-.-~," .... S--_~,i [J Use only as nmch water as necessallJT for dust control, to avoid mnoff. E'J Catch. drips fTom paving equipment that is not in use VIlith pans or absorbent material placed under the machines. Dispose of collected ma'u::erial and absorbents properly. Inspection o Have designated personnel conduct inspections of the parking facilities and stQrmwater conveyance systems associated with them on a regular basis. I1l Inspect cleaning equipment/sweepers for leaks on a regular basis. Trraining G Provide regular training to field employees and/or contractors regarding cleaning of paved areas and proper operation of equipment. ffi Train employees and contractors in proper techniques for spill containment and cleanup. Spill Response Qlt:lltd Preve1mtlo1m ~ Refer to SC-n, Spill Prevention, Control & Cleanup. [;] Keep your Spill Prevention Control and countermeasure (SPCC) plan up-to-date, mid implement accordingly . IJ Have spill cleanup materirus readily available and in a known location. o Cleanup spills immediately and use dry methods if possible. III Properly dispose of spill cleanup material. OtheJ· Considera.tions D lLimitations related to sweeping activities at large parking facilities may include high equipment costs, the need for sweeper operator training, and the inability of current sweeper technology to remove oil and grease. ReqtllBlremeli1lt:~ Costs Cleaning/sweeping costs can be quite large, 1C0nstmction and maintenance of stormwater structural'controls can be quite expensive as well. M([JJ.i:wtlZf{d.([JJ.7rw~ El Sweep parldng lot to minimize cleaning VIlith water. El Clean out oil/water/sand separators regularly, especially after heavy storms. Cl Clerurl parking facilities on a regular basis to prevent accumulated wastes and pollutants from being dlischarged into conveyance systems during reiny condlitions . January 2003 California Stormwater BMP I-Iandbook Municipal www.cabmphandbooks.com 30f4 ~(C=~~ EW@JE~rl«Q~~/~~~m;a@~~ ~G~~@ ~@lQlliir~~Q"Q@]D1~@ j~-. __ ._'~r,-::;:::","i_-<q;~" •• _,-,,,,_",,,.,~,~.,,, .. ~~,,~",,"," '-,,-~-... -~"' .... ,'-~ -~.--.~-~..,-,,-,.._ ... :::::: ••• _,,,,"~,,, ___ ~,_~,,,, __ ,,_~ '_"'~",,-,","-~_ •• _~._ ,~,..,.~ '""'_,,,".:..y --~-"""""~"-'-~"r ... ,,,.--~.> ... a~. , .. j ttlW ~~O<!!Ili1i<!!Oilil@O EOil~@.Ili1i"~"~HI1 iFT!J11f'ttikeu" Drett@.iE ([)Jf ttike JJJMP Surface Repair Apply concrete, asphalt, and seal coat during dry weather to prevent contamination form contacting stormwater runoff. Where applicable, cover and seal nearby storm drain inlets (wIth waterproof material or mesh) and manholes before applying seal coat, slurry seal, etc. Leave covers in place until job is complete and until all water from emulsified oil sealants has drained or evaporated. Clean any debris from these covered manholes and drClins for proper disposal. Use only as much water as necessary for dust control, to avoid runoff. ~®1f®If'®fiil~~~ ~fJ'iltdl ~~~@!l,!]If'~@~ http://www.stormwatercenter.net! California's Nonpoint SOUrce Program Plan http://www.swrcb.ca.gov Inps/index.html Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipalities. Prepared by City of Monterey, City of Santa Cruz, Californ~a Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality control Board. July 1998 (Revised February 2002 by the California Coastal Commission). aange County Stormwater Program ~:/ /www.ocwatersheds.com/StormWater/swp_introduction.asp Oregon Association of Clean Water Agencies. Oregon Municipal Stormwater Toolbox for Maintenance Practices. June 1998. Pollution from Surface Cleaning Folder. 1996. Bay Area Stormwater Management Agencies Association (BASMAA) http://www.basma.org San Diego Stormwater Co-permittees Jurisdictional Urban Runoff Management Program (URMP) http://www.projectcleanwater.org/pdf/Model%20Program%20Municipal%20Facilities.ruif • 4-of 4-California Stormwater BMP Hanclbook Municipal www.cabmphandbool<s.com January 2003 • • • I·· 1Ol~~~trnlJjt6@!i'il Streets, roads, and highways are significant sources of pollutants in stormwater discharges, and operation and maintenance (O&M) practices, if not conducted properly, can contribute to the problem, Stormwater pollution from roadway and bridge m2ljntenance should be addressed on a site-specific basis, Use of the procedures outlined below, that address street sweeping and repair, bridge and structure maintenance, and unpaved roads will reduce pollutants in stormwater, Appr@a©S'lJ PffJ)~~WJ:fiiffJ)1JR Pv°~'1JJ~1TO.UiffJ)1TO. 51 Use the least toxic materials available (e,g, water based paints, gels or sprays for graffiti removal) Q Recycle paint and other materials whenever possible, '0 Enlist the help of citizens to keep yard waste, used oil, and other wastes out of the gutter, §7!J1.fflJfflJ~stt®rff11P7f'({])fJ:ffJ)~({])1ls Street Sweeping and Cleaning G Maintain. a consistent sweeping schedule, Provide minimum monthly sweeping of curbed streets, [J Pell10rm street cleaning during dry weather if possible, January 2003 California Stormwater BMP Handbook Municipal www.cabl11phandbool{s.com (Q)[b),l)@©\l:D'¥'®f§5 [J Cover EI Contain l'!J Educate ~ Reduce/Minimize gj Product Substitution Sediment Nutrients Trash Metals Bacteria Oil and Grease Organics O){ygen Demanding J J J J J J • Avoid wet cleaning or flushing of street, and utilize dxy methods where possible. EI Consider increasing sweeping frequency based on factors such as traffic volume, land use, fi.eld observations of sediment and trash accumulation, prmdmity to water courses, etc. For example: Increase the sweeping frequency for streets with high pollutant loadings, especially in high traffic and industrial areas. Increase the sweeping frequency just before the wet season to remove sediments accumulated during the summer. Increase the sweeping frequency for streets in special problem areas such as special events, high litter or erosion zones. (;] Maintain cleaning equipment in good working condition and purchase replacement equipment as needed. Old sweepers should be replaced with new technologically advanced sweepers (preferably regenerative air sweepers) that maximize pollutant removal. f2l Operate sweepers at manufacturer requested optimal speed levels to increase effectiveness. (3 To increase sweeping effectiveness consider the following: .-Institute a parking policy to restrict parking in problematic areas during periods of street sweeping. Post permanent street sweeping signs in problematic areas; use tempormy signs if installation of permanent signs is not possible. Develop and distribute flyers notifying residents of street sweeping schedules. [J Regularly inspect vehicles and equipment for leaks, and repair immediately. o If available use vacuum or regenerative air sweepers in the high sediment and trash areas (typically industrialj commercial). [] Keep accurate logs of the number of curb-miles swept and the amount of waste collected. CiI Dispose of street sweeping debris and dirt at a landfill. I:l Do not store swept material along the side of the street or near a storm drain inlet. Gl Keep debris storage to a minimum during the wet season or make sure debris piles are contained (e.g. by berming the area) or covered (e.g. with tarps or permanent covers). Street Repair and Mainten.ance Pavemen.t mark.ing • Schedule pavement marking activities for dry weather. 2of9 California Stormwater BMP Handbook Municipal www.cabmphandbool<s.com January 2003 • • o Develop paint handling procedures for proper use, storage, and ilJUsposal of paints. Iij Transfer and load paint 2J..nd hot thermoplastic away from storm drain inlets. o Provide drop cloths and drip pans in paint mhdng areas. EJ Properly maintain application equipment. Dl Street sweep thermoplastic grindings. Yenow thermoplastic grindings may require special handling as they may contain lead. o Paints containing lead or tributyltin are considered a hazardous waste and must be disposed of properly. ' Q Use water based paints whenever possible. If using water based paints, clean the application equipment in ,a sink that is connected to the sanitary sewer. GI Properly store leftover paints if they are to be kept for the next job, or dispose of properly. Concrete installation and repair r::I Schedule asphalt and concrete activities for dry weather. D 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). Ii] Limit the amount of fresh concrete or cement mortar mixed, mix only what is needed for the job. Eil Store concrete materials under cover, away from drainage areas. Secure bags of cement after they are open. Be sure to keep vvind-blown cement powder away from streets, gutters, storm drains, rainfall, and runoff. D Return leftover materials to the transit mixer. Dispose of small amounts of hardened excess concrete, grout, and mortar in the trash. g 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. 13 When malting 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 contain the slurry by placing straw bales, sandbags, or gravel dams around the inlets. After the liquid drains or evaporates, shovel or 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 fr01;Il reaching storm drain inlets. [J Wash concrete trucks off site or in designated areas on site designed to preclude discharge of • wash water to drainage system. January 2003 California Stormwater BMP Handbook Municipal www.cabmpl.iandbooks.com 30f9 §)(CE3 1@ ~EQ)@@ @ffi1l(©] §)i:Qg@~fc ~@J@mlJu:~rrn@ul]~® 1,,---,.,-,.,.,..-~'''~~'' ~-_. __ " __ '_~ __ '_.' J ___ •• ,,,_-. __ , -_~._ •• ~,",,-"C'" -..,::;;::z,..., .... ....-~ __ ~.-_.~~_,~,..." ....... ,....., ~ T-.-,.., • .....-_ ... ..--.?_<_-_ •• ~ .... • ... ..,.7 " __ ~,, .... ~--'"""'..-"'."""_ -,_, ..... ~_,~.""._ ... __ ... ,_~~ _~_ . .-._-<".,....I e Patchingp resurfacingp and surface sealing o Schedule patching? resurfacing 1,Uld surface sealing for dr.ry weather. s Stockpile materials away from streets, gutter areas, storm drain inlets or watercourses. During wet weather, cover stockpiles with plastic tarps or berm around them if necessary to prevent transport of materials in runoff. o Pre-heat, transfer or load hot bituminous material away from drainage systems or watercourses. El Where applicable, cover and seal nearby storm drain inlets (with waterproof material or mesh) and maintenance holes before applying seal coat, slurry seal, etc. Leave covers in place until job is complete and until all water from emulsified oil sealants has drained or evaporated. Clean any debris from covered maintenance holes and storm drain inlets when the job is complete. . ID Prevent excess material from exposed aggregate concrete or similar treatments from entering streets or storm drain inlets. Designate an area for clean up and proper disposal of excess materials. [3 Use only as much water as necessary for dust control, to avoid runoff. e Sweep, never hose down streets to clean up trac1(ed dirt. Use a street sweeper or vacuum truck. Do not dump vacuumed liquid in storm drains. Cl Catch drips from paving equipment that is not in use with pans or absorbent material placed under the machines. Dispose of collected material and absorbents properly. Equipment cleaning maintenance and storage o Inspect equipment daily and repair any leaks. Place drip pans or absorbent materials under heavy equipment when not in use. G Perform major equipment repairs at the corporation yard, when practical. [j If refueling or repairing vehicles and equipment must be done onsite, use a location away from storm drain inlets and watercourses. El Clean equipment including sprayers, sprayer paint supply lines, patch and paving equipment, and mud jacking equipment at the end of each day. Clean in a sink or other area (e.g. vehicle wash area) that is connected to the sanitary sewer. Bridge and Structure Maintenance Paint: and Paint Removal IJ Transport paint and materials to and from job sites in containers with secure lids and tied ed01l\lIl to the transport vehicle. o Do not transfer or load paint near storm. drain inlets or watercourses. 4of9 California Stormwater BMP i-Iandbool{ January 2003 Municipal www.cabmphandbooks.com I I ... ~ • • • [J Test and inspect spray equipment prior to starting to paint. Tigl1ten aU hoses and connections and do not overfill paint container. o Plug nearby stDrm drain inlets priQr tD starting painting where there is significant risk of a spill reaching storm drains. RemQve plugs when jDb is cDmpleted. §] If sand blasting is used to remDve paint, cover nearby stQrm drain inlets priQr to starting work. IJ PerfQrm wQrk IOn a maintenance traveler lOr platfQrm, lOr use suspended netting Dr tarps tQ captllre paint, rust, paint remDving agents, lOr Dther materials, tD prevent discharge Qf materials tD surface waters if the bridge crosses a watercDurse. If sanding, use a sander "With a vacuum filter bag. G Capture all clean-up water, and dispDse Df prDperly. [] Recycle paint when possible (e.g. paint may be used fDr graffiti remDval activities). DispDse Df unused paint at an apprQpriate hDusehDld hazardDus waste facility. Graffiti Removal El Schedule graffiti remDval activities fQr dry weather. o Protect nearby stQrm drain inlets priQr tQ remQving graffiti frDm walls, signs, sidewalks, Dr Dther structures needing graffiti abatement. Clean up afterwards by sweeping Dr vacuuming thDrQughly, and/ lOr by using absQrbent and properly disPQsing Qf the absQrbent. [jJ When graffiti is remQved by painting lOver, implement the procedures under Paintblg and Paint Removal above. El Direct runDfffrDm sand blasting and high pressure washing (with nD cleaning agents) i11tD a landscaped lOr dirt area. If such an area is nQt available, filter runDff thrQugh an apprQpriate filtering device (e.g. filter fabric) to keep sand, particles, and debris out of storm drains. fil If a graffiti abatement methDd generates wash water cDntaining a cleaning cDmpDund (such as high pressure washing with a cleaning compDund), plug nearby storm drains and vacuum/pump wash water tQ the sanitary sewer. I.:l CDnsider using a waterless and non-tQxic chemical cleaning method fDr graffiti removal (e.g. gels lOr spray cDmpounds). Repa.ir Work CJ Prevent concrete, steel, wood, metal parts, tools, or other work materials from entering storm drains or waterCQurses. 8 ThorQughly clean up the jQb site when the repair work is cDmpleted . El When cleaning guardrails lOr fences foIlQW the appropriate surface cleaning methods (depending on the type of surface) outlined in §C-71 Plaza & Sidewalk Cleaning fad sheet. January 2003 California Stol"mwater BMP Handbook Municipal www.cabmphandbooks.com 50f9 ·., ...... ( ........ ,.,._ .... , , GJ If painting is conducted, follow the painting and paint remov~l procedures above. m If graffiti removal is conducted, follow the graffiti removal procedures above. o If construction t2lJees place, see tllle Construction Activity BMP H3-ndbook. (] Recycle materials whenever possible. Unpaved Roads and Trails D Stabilize exposed soil areas to prevent soil f-rom eroding during rain events. This is particularly important on steep slopes. (] For roadside areas with exposed soils, the most cost-effective choice is to vegetate the area, preferably with a mulch or binder that will hold the soils in place while the vegetation is establishing. Native vegetation should be used if possible. [3 If vegetation cannot be established immediately, apply temporary erosion control matsfblankets; a comma straw, or gravel as appropriate. D If sediment is already eroded and mobilized in roadside areas, temporary controls should be installed. These may include: sediment control fences, fabric-covered triangular dikes, gravel-filled burlap bags, biobags, or hay bales staked in place. en-stormwater Discharges Field crews should be aware of non-stormwater discharges as part of their ongoing street maintenance efforts. Ell Referto SC-lO Non-Stormwater Discharges rn Identify location, time and estimated quantity of discharges. fii! Notify appropriate personnel. Tlraining @ Train employees regarding proper street sweeping operation and street repair and maintenance. o Instruct employees and subcontractors to ensure that measures to reduce the stormwater impacts of roadway Ibridge maintenance are being followed. G Require engineering staff andlor consulting AlE firms to address stormwater quality in new bridge designs or existing bridge retrofits. . o Use a training log or similar method to document training. [J Train employees on proper spin containment and dean uP. and in identifying non- • stormwater discharges. ! ...... ,,",p._ 'Q~<--0" .c. ! 6of9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.col11 • • • §jpJilUU lPl.ft~jpJ@7J71$1Z (JJjJj71a11 J!!7JolZ7!JIZ7171rtll.@7171 o Refer to SC-ll, Spill Prevention, Control &. Cleanup. [;J Keep your Spill Prevention Control and countermeasure (SPCC) plan up-to-date,-and implement accordingly. IT! Have spill cleanup materials readily available and in a known location. IEl Cleanup spills immediately and use dry methods if possible. 1!3 Properly dispose of spill cleanup material. Otheoo C07rwiriJleif01rtll.@7J71~ 1'3 Densely populated areas or heavily used streets may require parldng regulations to clear streets for cleaning. EJ No currently available conventional sweeper is effective at removing oil and grease. Mechanical sweepers are not effective at removing finer sediments. I!l Limitations may arise in the location of new bridges. The availability and cost ofland and other economic and political factors may dictate where the placement of a new bridge will . occur. Better design of the bridge to control runoff is required if it is being placed near sensitive waters . ~~@,jllJjh"~m~Ii'il'lt~ C@~11:$ til The maintenance of local roads and bridges is already a consideration of most community public works or transportation departments. Therefore, the cost of pollutant reducing management practices will involve the training and equipment required to implement these new practices. [I The largest expenditures for street sweeping programs are in staffing and equipment, The capital cost for a conventional street sweeper is between $60,000 and $120,000. Newer technologies might have prices approaching $180,000. The average useful1ife of a conventional sweeper is about four years, and programs must budget for equipment replacement. Sweeping frequencies will determine equipment life, so programs that sweep more often should expect to have a higher cost of replacement. !iii A street sweeping program may require the following. Sweeper operators, maintenance, supervisory, and administrative personnel are required. Traffic control officers may be required to enforce parking restrictions. Skillful design. of cleaning routes is required for program to be productive . .A1rangements must be made for disposal of collected wastes . January 2003 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com 7of9 • If investing in newer technDlDgies, training fDr DperatDrs must be included in DperatiDn and maintenance budgets. CDsts fDr pubUc educatiDn are small, and mOIstly deaJ with the need tD Dbey parking restrictiDns and litter cDntrot Parking tickets are an effective reminder tD Dhey paddng mles, as wen as being a sDurce Df revenue. M@iTlilf!:<eTlil(i)lTlil~<e [] Not applicable ~MbQl[p)~~m®B'tl1!:~U lrliilf@If'U'fi'il@J1!:u@1iil JF1!Jl1rf!:lfo.<e1r J/])<ef!:(i)liU @j'ftlfo.<e JEMJI» Street sweeping There are advantages and disadvantages tD the twD common types Df sweepers. The best choice depends on your specific cDnditiDns. Many communities find it useful tD have a cDmpliment Df both types in their fleet. Mechanical Broom Sweepers -MOIre effective at picking up large debris and cleaning wet streets. Less costly to purchase and operate. Create more airbDrne dust. Vacuum Sweepers -More effective at removing fine particles and associated heavy metals. Ineffective at cleaning wet streets. Noisier than mechanical broom sweepers which may restrict areas Dr times of operation. May require an advance vehicle to remove large debris. ~et Flushers -NDt affected by biggest interference to cleaning, parked cars. May remDve finer ~iments, moving them toward the gutter and stDrmwater inlets. For this reason, flushing fell Dut Df favor and is now used primarily after sweeping. Flushing may be effective fDr combined sewer systems. Presently stTeet flushing is not allowed under most NPDES permits. Cross-Media Transfer of Pollutants The California Air Resources Board (ARB) has established state ambient air quality standards including a standard for respirable particulate matter Oess than or equal to 10 microns in diameter, symbolized as PMw). In the effort to sweep up finer sediments to remove attached heavy metals, municipalities should be aware that fine dust, that cannot be captured by the sweeping equipment and becomes airborne, could lead to issues of worker and public safety. Bridges Bridges that carry vehicular traffic generate some of t.he more direct discharges of runoff to surface waters. Bridge scupper drains cause a direct discharge of stormwater into receiving waters and have been shown to carry relatively high concentrations of pollutants. Bridge maintenance also generates wastes that may be either directly deposited to the water below or carried to the receiving water by stormwater. The following steps will help reduce the stormwater impacts of bridge maintenance: [] Site new bridges so that significant adverse impacts to wetlands, sensitive areas, cdtical habitat, and ripari2l.1l vegetation are minimized. • - 8of9 California Storrnwater BMP Handbook Municipal www.cabmphandbooks.coli1 January 2003 • • • o Design new bddges to avoid the use of scupper drams and route runoff to land for treatment control. Existing scupper drains should be cleaned on a regular basis to avoid sediment! debris accunmlationo . IJl Reduce the discharge of pollutants to surface waters during maintenance by using suspended traps, vacuums, or booms in the water to capture paint, rust, and paint removing agents 0 Many of these wastes may be hazardouso Properly dispose of this waste by referring to eA2! (Hazardous Waste Management) in the Construction Handbook . III Train employees and subcontractors to reduce the discharge of wastes during bridge maintenanceo De-icing Ii!! Do not over-apply deicing salt and sand, and routinely calibrate spreaderso II Near reservoirs, restrict the application of deicing salt and redirect any runoff away from reservoirso Ilil Consider using alternative deicing agents Oess tmac, biodegradable, etc.)o References and lRe~@ur«:e~ Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municip8Jitieso Prepared by City of Monterey, City of Santa Cruz, California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Boardo July. 19980 Orange County Stormwater Program http..;Llwww.ocwatersheds.com/stormwaterlsw introduction. asp Oregon Association of Clean Water Agencieso Oregon Municipal Stormwater Toolbox for Maintenance Practiceso June 1998. Santa Clara Valley Urban Runoff Pollution Prevention Programo 1997 Urban Runoff Management Plano September 1997, updated October 2000. Santa Clara Valley Urban Runoff Pollution Prevention Programo 20010 Fresh Concrete and Mortar Application Best Management Practices for the Construction. Industryo June. Santa Clara V2IJley Urban Runoff Pollution Prevention Programo 2001. Roadwork and Paving Rest Management Practices for the Construction ][ndustFY. June. United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Roadway and Bridge Maintenance. On-line http://www.eDa.gov!npdes/menuotbmJ!)ls/nollJl3.htm ' January 2003 California Stormwater BMP Handboo!( Municipal www.cabmphandbool<socom 9 of 9 • • • !L@J ~l) @ ~«:@ EQJ~ ~ ~ ~ 61r~~ wll @ ~lj ~® _ ~ _" ,-... , <4 ~~ ~ +. _ r ~._,.. "~,~ ..... ~_. ''''~"_~" .. ~ __ +0'_ _. _, _~ _ -~ __ .~ ... ...-_.'_ ,.4¥ _._ ......... "~~~.,, ""_-"""_' -.. ~<><-.P _ • ,--. --t- [lJ~~~IfUpfJ:O@Hlil Landscape maintenance activities include vegetation removal; herbicide and insecticide application; fertilizer application; watering; and other gardening and lawn care practices. Vegetation control typically involves a combination of chemical (herbicide) application and mechanical methods. All of these maintenance practices have the potential to contribute pollutants to the storm drain system. The major objectives of this EMP are to minimize the discharge of pesticides, herbicides and fertilizers to the storm drain system and receiving waters; prevent the disposal of landscape waste into the storm drain system by collecting and properly disposing of clippings and cuttings, and educating employees and the public. t%.lP-lpll"@~~fhl JID([})~~TI1!:ftff.I[}1J7l. JIDTJ"IETJJi&1J7l.KP.([})1J7l. EI Implement an integrated pest management (IPM) program. IPM is a sustainable approach to managing pests by combining biological, cultural, physical, and chemical tools. o Choose low water using flowers, trees, sumbs, and groundcover. o Consider alternative landscaping techniques such as naturescap:i.ng a!ld xedscaping. [iJ Conduct appropriate maintenance (i.e. propedy timed fertilizing~ weeding, pest control, and plrlli!1:i.ng) to help preseI'Ve the landscapes water efficiency. January 2003 California Storrnwater BMP Handbook Municipal www.cabrnphanclbooks.com III Contain o Educate o Reduce/Minimize §l Product Substitution lr@(j"@I@il:@~t] te@liil~ituitl!J.l@Iiil\l:~ Sediment '" Nutrients Trash Metals Bacteria Oil and Grease Organics Oxygen Demanding 1 of6 ~[;= #~ l@WiJ©]~~~[9J~' 80B~06lJU:~mJ®)01)~® •• ~-.. • •. -••. _ •.••• -' • --•• --.............. ~-., ~-..... ~ .. -.-•• --.-...... ,.~ ....... ., ~." ........... -.......................... ' .... . • •••• • ....... " ...... , .j o Consider grass cycling (grass cycling is the natur8l1 recycling of grass by leaving tll1e clippings on the lawn when H1.owing. Grass clippings decompose quiddy and release valuable . nutrients back into the lawn). §VJlffJJ@~$(f;~fllf.lI?1N]Jtt@~@li2 Mowing, Trimming, and Weeding o Whenever possible use mechanical methods of vegetation removal (e.g mowing with tractor- type or push mowers, hand cutting with gas or electric powered weed trimmers) rather than applying herbicides. Use hand weeding where practical. E3 Avoid loosening the soil when conducting mechanical or manual weed control, this could' lead to erosion. Use mulch or other erosion control measures when soils are ex-posed. [] Performing mowing at optimal times. Mowing should not be performed if significant rain events are predicted. I!1l Mulching mowers may be recommended for certain flat areas. Other techniques may be employed to minimize mowing such as selective vegetative planting using low maintenance grasses and shrubs. . • Collect lawn and garden clippings, pruning waste, tree trimmings, and weeds. Chip if . necessary, and compost or dispose of at a landfill (see waste management section of this fact sheet). 19 Place temporarily stockpiled material away from watercourses, arid berm or cover stockpiles to prevent material releases to storm drains. Pla1J1J.ting Ii] Determine existing native vegetation features Oocation, species, size, function, importance) and consider the feasibility of protectin.g them. Consider elements such as their effect 011 drainage and erosion, hardiness. maintenance requirements, and possible conflicts between preserving vegetation and the resulting maintenance needs. Q Retain and/or plant selected native vegetation whose features are determined to be benefiCial, where feasible. Native vegetation usually requires less maintenance (e.g., irrigation, fertilizer) than planting new vegetation. EI Consider using low water use groundcovers when planting Of replanting. W (Il$t~ M(JJlwlJJlffJJemefl1lti: G Compost leaves, sticks, or other collected vegetation or dispose of at a permitted landfill. Do not dispose of collected vegetation into waterways or storm drainage systems. El Place temporarily stockpiled material away from watercourses and storm drain inlets, 2l.nd berm or cover stockpiles ito prevent material releases to the stm.m drain system. • Reduce the use of high nitrogen fertilizers that produce excess growt.h. requiring mote frl'equent mowing or trimming. 2of6 California Stormwater BMP Handbook Municipal www.cabmphanclbooks.com January 2003 • • • l@ ITi)~J~GC@ GQ)~ ~@ illlTI)t:~cru@ lJ1e:~ ,, ___ ~"' .,, ___ ~ ____ -..,_"~, __ ,, __ .. ..,.. .. _,_ .... _~_-_~ _____ '_'~~' __ ~~""""~'_"~~''''''''-''''''''''~''''-<" __ :; ___ '~'''7~'''''-' __ ,,",,,,_ "". __ .,.. •. <..,..F?y' _____ _ [j Avoid landscape wastes in and around storm drain inlets by either using bagging equipment or by manually piddng up the material. lI1J"1J"ii@([JltU.([})7fD. G Where practical, use automatic timers to minimize runoff. 19 Use popup sprinkler heads in areas with a lot of activity or where there is a chance the pipes may be broken. Consider the use of mechanisms that reduce water flow to sprinkler heads if broken. f1>I Ensure that there is no runoff from the landscaped area(s) if re-claimed water is used for irrigation. [J Ifbailing of muddy water is required (e.g. when repairing a water line leak), do not put it in the storm drain; pour over landscaped areas. Ii! Irrigate slowly or pulse irrigate to prevent runoff and then only irrigate as much as is needed. Ii!J Apply water at rates that do not exceed the infiltration rate of the soil. Fel~lizea· a:nd Pe£rHidde Ma1fd/lJlgementt Ii! ,utilize a comprehensive management system that incorporates integrated pest m~agement (IPM) techniques. There a..re many methods and types of IPM, including the following: - . Mulching can be used to prevent weeds where turf is absent, fencing installed to keep rodents out, and netting used to keep birds and insects away from leaves and fruit. Visible insects can be removed by hand (with gloves or tweezers) and placed in soapy 'water or vegetable oil. Alternatively, insects can be sprayed off the plant with water or in some cases vacuumed off of larger plants. . Store-bought traps, such as species-specific, pheromone-based traps or colored sticky cards, can be used. Slugs can be trapped in small cups filled with beer that are set in the ground so the slugs can get in easily. In cases where microscopic parasites, such as bacteria and fungi, are causing d~mage to plants, the affected plant material can be removed and disposed of (pruning equipment should be disinfected with bleach to prevent spreading the disease organism). Small mammals and birds can be excluded using fences, netting, tree trunk guards. Beneficial organisms, such as bats, birds, green lacewings, ladybugs, praying mantis, ground beetles, parasitic nematodes, trichogramma wasps, seed head weevils, and spiders that prey on detrimental pest species can be promoted . EJ Follow all federal, state, and local laws and regulations governing the use, storage, and disposal of fertilizers and pesticides and training of applicators and pest control advisors. January 2003 California Stormwater BMP Handbook Municipal www.cabmphandboo!<s.cOlll 30f6 l@ffi,d~~@J~~ ~~Blmlie~lfID@lfij~~ \ ____ >_,~_""'__-_,,~~ •• M·_'~,~ __ 3_ i,,> .... ·,',. _~.,.....,,~!. b_",..=·",-<.-__ ._,._·,,_..-_~~,_·_ ..... _ '.,' .. _<..._ ... >.'r ...... ~ . ..., ·~<>J ..... , ..... , .... _v_._~._ ...... ..,...~, ..... _~_·._. Y'_,.. ..... ~_ ...... _, ... _ .... , ... ~,~ .. ~.~<-..,Q."' __ ~_ ~ __ ~~,... _I • Use pesticides only if there is an actual pest problem (not on a regular preventative schedule). 6l Do not use pesticides if rain is expected. Apply pesticides only when wind speeds are low (less th.an 5 mph). [iJ Do not mix or prepare pesticides for application near storm drains. 13 Prepare the minimum amount of pesticide needed for the job and use the lowest rate that win effectively control the pest. EI Employ techniques to minimize off-target application (e.g. spray drift) of pesticides, including consideration of alternative application techniques. m Fertilizers should be worked into the soil rather than dumped or broadcast onto the surface. I.E Calibrate fertilizer and pesticide application equipment to avoid excessive application. [iJ Periodically test soils for determining proper fertilizer use. D Sweep pavement and sidewalk if fertilizer is spilled on these surfaces before applying irrigation water . • purchase only the amount of pesticide that you can reasonably use in a given time period (month or year depending on the product). EI Triple rinse' containers, and use rinse water as product. Dispose of unused pesticide as hazardous waste. El Dispose of empty pesticide containers according to the instructions on the container label. Inspection EI Inspect irrigation system periodically to ensure that the right amount of water is being applied and that excessive runoff is not occurring. Minimize excess watering, and repair leaks in the irrigation system as soon as they are observed. EI InSPect pesticide/fertilizer equipment and transportation vehicles daily. n Ol!J1.i1l1li1l1lg o Educate and train employees on use of pesticides and in pesticide application techniques to prevent pollution. Pesticide application must be under the supervision of a Californ,ia qualified pesticide applicator. [] Train/encourage municipal maintenance crews to use IPM techniques for managing public green areas. Ii:1 Annually train employees within departments responsible for pesticide application on the • approPriate portions ofllie agency's IPM Policy, SOPs, and lBMPs, and the latest ][PM techniques. r_ 4-of6 California Stormwater BMP Handbook Municipal www.cabmphandbool<:s.col11 January 2003 • • • o Employees who are not authorized and trained to apply pesticides should be pe:d.odicaJly (at least annually) h1formed that they can.11ot use over-the-cov.1lter pesticides in or around the workplace. IT] Use a training log or similar method to document training. §]{piUU R.12§]{p@1J1I.$12 I!ll.Tfil/DY lPiJo127JJ127Tl1.ttll.@7TlI. [ill Refer to SC-n, Spill Prevention, Control & Cleanup E'I Have spill cleanup materials readily available and in a know in location fa Cleanup spills immediately and use dry methods if possible. tTI Properly dispose of spill cleanup material. Othe1J' ConsiderattO.oTfUil i1iI The Federal Pesticide, Fungicide, and Rodenticide Act and California Title 3, Division 6, Pesticides and Pest Control Operations place strict controls over pesticide application and handling and specify training, annual refresher, and testing requirements. The regulations generally cover: a list of approved pesticides and selected uses, updated regularly; general application information; equipment use and maintenance procedures; and record keeping. The California Department of Pesticide Regulations and the County Agricultural Commission coordinate and maintain the licensing and certification programs. All public agency employees who apply pesticides and herbicides in "agricultural use" areas such as parks, golf courses, rights-of-way and recreation areas should be properly certified in accordance with state regulations. Contracts for landscape maintenance should include similar requirements. o All employees who handle pesticides should be familiar with the most recent material safety data sheet CMSDS) files. Q Municipalities do not have the authority to regulate the use of pesticides by school districts, however the California Healthy SchOlOlls Act of 2000 CAB 2260) has imposed requirements on CalifOlrnia schoOll districts regarding pesticide use in schools. Posting of notification prior to the applicatiOln of pesticides is now required, and IPM is stated as the preferred approach to pest management in schOlols. R~qUlQf'em~S'ilt~ C@/S(f:s Additional training Olf municipal employees will be required to address IPM techniques and BMPs. IPM metlhods will Ukely increase labDr cost fDr pest control which may be Dffset by lower chemical costs. Ma:ii.nit®7TlI.1!ll.7TlI.~® Not applicable January 2003 California Stormwater BMP Handbook Municipal www.cabmphanclbooks.com .5 of6 ·v'~~' ,,_, __ , __ , ______ -" ,'" ,,_, ~-. "''''''-"""""_".,_,,_,,,,,, __ >,,_~__ "".,_n._", -. "-, ____ ,0> ' ___ L,,~' ___ " ~"''''>_" ~ .. -_, __ <>','''-d~-' '«_ ,,, .. ,,,," ''' __ '''' ___ ''"''M __ ~"'" ~l1!lbQ)fP-)~@n1l1l®lfill1©.1~ 1i:fiillr@Ii"Ii'il'lJ@.l110@1fil 1F7lJl1J°tJ:U1!.~71° l!J~tJ:I!J!:llJ lIJ)j'ttU1!.~ JEMJIP Waste Management Composting is one of the better disposal alternatives if locally available. Most municipalities either have or are planning yard waste composting facilities as a means of reducing the amount of waste going to the landfill. Lavvn clippings from municipal maintenance programs as wen as private sources would probably be compatible with most composting facilities Contractors and Other Pesticide Users Municipal agencies should develop and implement a process to ensure that any contractor employed to conduct pest control and pesticide application on municipal property engages in pest control methods consistent with the IPM Policy adopted by the agency. Specifically, municipalities should require contractors to foHow the agency's IPM policy, SOPs, and BMPs; provide evidence to the agency of having received training on current IPM techniques when feasible; provide documentation of pesticide use on agency property to the agency in atimely manner. ~®f®Il"~Iiil«;:®~ @l!i1l{Qi ~®~@[jJJ[j"«;:®~ King County Stormwater Pollution Control Manual. Best Management Practices for Businesses. 1995. King County Surface Water Management. July. On-line: .J;tiLdnr.metrokc.gov /wlr / dss/spcm.htm Los Angeles County Stormwater Quality Model Programs. Public Agency Activities htID: //ladpw.org/wmd/npdes/model links.cfm Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipaiities. Prepared by City of Monterey, City of Santa Cruz~ California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. Orange County Stormwater Program ~:llwww.ocwatersheds.com/Storm Water Iswp introduction. asp Santa Clara Valley Urban Runoff Pollution Prevention Program. 1997 Urban Runoff Management Plan. September 1997, updated October 2000. United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Landscaping 21Jild Lawn Care. Office of Water. Office of Wastewater Management. On-line: http:f..1www.epa.gov/npdes/menuofbm~o1l8.htm • foe 6 of 6 California Stofmwater BMP Handbool< Municipal www.cabmphandbooks.com ,-, ~ ••• " .,.,,..,.1 JClnUcH'Y 2003 • • • [Ul8~@)80lJ@@® §W§)f1~M ~@gIDl]1t~DlJ@Q1j~~ ~e;= 7l~ I.A.. > _,_ .~, _ •• ____ .". __ ~ ~~, ,-,< .~"~'. _. __ .~~ .. ,' ___ " .""_ ••• ~-! Photo Credit: Geoff Brosseau [»~~~lrfiJPltij@U'll As a consequence of its function, the stonnwater conveyance system collects and transports urban runoff that may contain certain pollutants. Maintaining catch basins, stmmwater inlets, and other stormwater conveyance structures on a regular basis will remove pollutants, prevent dogging of the downstream conveyance system, restore catch basins' sediment trapping capacity, 21.nd ensure the system functions properly hydraulically to avoia flooding. . ApfP)Il"@@~!lil SW1gge!;1'rt~crIllPrr([})tlJ[j)~([})l/.$ Catch Basins/Inlet Structures El Municipal staff should regularly inspect facilities to ensure the following: Immediate repair of any deterioration threatening structural integrity. Cleaning before the sump is 40% full. Catch basins should be cleaned as flrequently as needed to meet this standard. Stenci1:i.ng of catch basins and inlets (see SC-75 Waste Handling and Disposal). o Clean catch basins, storm drain inlets, and other conveyance structures in high pollutant load areas just before the wet season to remove sediments and debris accumulated during the summer. January 2003 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com G Contain G Educate [J Reduce/Minimize -------,=--=---=-= Sediment Nutrients Trash Metals Bacteria Oil and Grease Organics O){ygen Demanding =---=--_.-------========= $(t@Jj'IillilWeJ~li' @lY.iaJn~ ~@<sU®liIJ@!i'il J <of J ~ ,f <I' J ,f 1 of 9 ~(C= y~J ~r@Jm~ll@J~~ ~w~li:~~~'1l U¥ill@jo5l)tt~ol)@W1)~@ , _ ~ ... -~ ___ ~,c:: _~ '~"T -,. ___ ~~, ~ ~"'. .'." ¥ " _" ~,'~ _ ".. ,<<--,.-,"<v, • ..,. -_"",_~ ,",, ___ ,.' __ < '~_""P"¥.,,.""'u<,,~,,_..,.,..., ,"',"'-_ ,~ ...... ~ ... """ ~.~ .... ~ ~ _,_ .• _.,,_ ~ _ • "_""_~C ."",,;;~ ~",~",,-•• , _ ''''-.' -,_",' __ , "'" ____ ~_, h _ .(~~. ~ .•• , • Conduct inspedions nu»re frequently during the wet season for problem areas where sedil1t1ent or trash accumulates mOiL'€; oaen. Clean and repair as needed. 1:1 Keep accurate logs of the nmnber of catch basins cleaned. o Record the amount of waste collected. o Store wastes collected from cleaning activities of the drainage system in appropriate containers or temporary storage sites in a manner that prevents discharge to the storm drain. ill Dewater the wastes with oun9.ow into the sanitary sewer if permitted. Water should be treated with an appropriate filtering device prior to discharge to the sanitary sewer. If discharge to the s~ .. nitary sewer is not allowed, water should be pumped or vacuumed to a tank and properly disposed of. Do not dewater near a storm drain or stream. [J 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 Corzveyance System o Locate reaches of storm drain 'With deposit problems and develop a flushing schedule that • keeps the pipe clear of excessive buildup. o Collect flushed effluent and pl!Jill1p to the s8lJi1itary sewer for treatment. Pump Stations Q Clean all storm drain pump stations prior to the wet season to remove silt il..nd trash. G Do not allow discharge from cleaning a storm drain pump station or other facility to reach the storm drain system. B Conduct quarterly routine maintenance at each pump station. m Inspect, clean, and repair as necessary all outlet structures prior to the wet season. El Sample collected sediments to determine if l8lJi1dfill disposal is possible, or illegal discharges in the watershed are occurring. Open Channel El Consider modification of storm channel characteristics to improve channel hydraulics, to increase pollutant removals, and to enhance channel! creek aesthetic and habitat value. [) Conduct channel modification/improvement in accordance with existing laws. Any person, government agency, or public utility proposing an activity that 'Win change t..he natural • (emphasis added) state of any river, stream, or lake in C2IJifornia, must enter into a st~am or Lruce Alteration Agreement with the Dep2lItment of Fish and Game. The developer-applic8lJi1t s1o.o1l..1I1d ruso contact loc2Jl governments (city, county, special districts), other state agencies 2of9 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com January 2003 • • • ~D" I::~:]I;:;;\ ~ rfi'l Si) r'fi"lo' : rEr\ ~ 'V:.fl r,;;:::.f?p ~ /j'l:~ ~$l?J ~ [Rll~ r6:\ r."'t:I ;:?) fiR\ rr rEF. ~,rr, OJ {J 61, l'd>' tJ (G!J iJ I:J 121 @ ~ \:Si ~ it 8J I:!::,~ ld iJ tJ I;jvrJ (2211] Jj [] 11~ fJ U <l9J U I;] \b:I18 t;V\b::J IY ~ \ ... '_u •. ~ -'".-~ <_..,., ...... ~'_"' ...... _"_: ___ • -~_,,_., ~~ -> v-........ ~ •• __ 1_ .... ' -\ ~ -~, ~~ ._~ , __ -~~. ~ ___ '~,_....,.. __ , r: ~. ~,<_ •• _.1_ ,, __ ,-, ... ~ ~~ -.,_, _'"" ..... , .. ;:.._,., ~ '-'~-~'~V-<J""."" __ ~",,"'~ -~ _, _ .¥ ~_ L ~ .... '-...,' .. ", _ •• -r'-...... ~ __ ,_ , I (SWRCJa, RWQCJa, Department of Forestry, Department of Water Resources), and Federal Corps of Engineers and USlFWS Illicit Connections and Discha'rges El During routine maintenance of conveyance system and drainage st..ructures field staff should look for evidence of illegal discharges or illicit connections: Is there evidence of spills such as paints, discoloring, etc. Are there any odors associated with the drainage system Record locations of apparent illegal discharges/illicit connections Track flows back to potential dischargers and conduct aboveground inspections. This can be done through visual inspection of up gradient manholes or alternate techniques including zinc chloride smoke testing, fluorometric dye testing, physical inspection testing, or television camera inspection. Once the origin of flow is established, require illicit discharger to eliminate the discharge. bl Stencil storm drains, where applicable, to prevent illegal disposal of pollutants. Storm drain inlets should have messages such as "Dump No Waste Drains to Stream" stenciled next to them to warn against ignorant or intentional dumping of pollutants into the storm drainage system. l!! Refer to fact sheet SC-lO Non-Stormwater Discharges. Illegal Dumping I!I Regularly inspect and clean up hot spots and other storm drainage areas where illegal dumping and disposal occurs. I!I Establish a system for tracking incidents. The system should be qesigned to identify the following: megal dumping hot spots Types and quantities (in some cases) of wastes Patterns in time of occurrence (time of day/night, month, or year) Mode of dumping (abandoned containers, "midnight dumping" from moving vehicles,. direct dumping of materials, accidents/spills) Responsible parties El Post "No Dumping" signs in problem areas with a phone number for reporting dumping and disposal. Signs should ruso indicate fines and penalties for illegal dumping . Q Refer to fact sheet SC-to Non-Stormwater Discharges . . n" + ,,:-,J, >,,""V January 2003 California Storl11water BMP Handbook 3 of 9 Municipal www.cabmphandbooks.com e" . '-.. , .... " .. , .. "., '." .... , .... -"-"",j """"'''''''''-''''''-... " .... ,,,.,,"'" .~ ... ,," ><" ..... ,',"_.,-........... " .. "'" 0. .. " ....... 0..,,,,,,, .. ,,, ."'''''' .... " ...... -,-,,', ...... " .j El Th.e State Department of Fish and Game has a hotline for reporting violations called Cal TIP (1-800-952-5400). The phone nmnbel' may be used to report any violation of a Fish and Game code (illegal dumping, poaching, etc.). o The California Department of Tm .. ic Substances Control's Waste .Alert Hotline, 1-800- 69TOXIC, can be used to report hazardous waste violations. 'lru"@.if.1J1!.if.1J1!.!Jj o Train crews in proper maintenance activities, including record keeping and disposal. Q Only properly trained individuals are allowed to handle hazardous materials/wastes. I:il Train municipal employees from all departments (public works, utilities, street cleaning, parks and recreation, industrial waste inspection, hazardous waste inspection, sewer maintenance) to recognize and report illegal dumping. ~ Train municipal employees and educate businesses, contractors, and the general public in proper and consistent methods for disposal. Ell Train municipal staff regarding non-stormwater discharges (See se-lO Non-Stormwater Discharges): ki~~ Re$pq:p1J1!.$e ([Jl1J1!.iIl1P1r~lJJ~1J1!.t8.([P1J1!. • Refer to SC-ll, Prevention, Control &: Cleanup o Have spill cleanup materials readily available and in a known location. [] Cleanup spills immediately and use dry methods if possible. i1'l Properly dispose of spill cleanup material. OttlhreTf' C01Ji!.$iileD"@.ttU.@1Ji!.$ 13 Cleanup activities may create a slight disturbance for local aquatic species. Access to items and material on private property may be limited. Trade-offs may exist between channel hydraulics and water quality/riparian habitat. If storm channels or basins are recognized as wetlands, many activities, including maintenance, may be subject to regulation and permitting. EI Storm drain flushing is most effective in small diameter pipes (36-inch diameter pipe or less, depending on water supply and sediment collection capacity). Other considerations associated with storm drain flushing may include the availability of a water source, finding a downstream area to collect sediments, liquid/sediment disposal, and disposal of flushed effluent to sanitary sewer may be prohibited in some areas. o Regulations may include adoption of substantial pemdties for illegal dumping and disposal. £:] Municipal codes should include sections prohibiting the discharge of soil, debris, refuse, • hazardous wastes, and other poUutants into Lhe storm d.rain system. Ii] Private property access rights may be needed to track illegal discharges up gradient. 4of9 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com January 2003 • • • ID3G~@~Blj@J~~ §)W~ic~wtrul ~@]0Bt1f!;~lf1J@Hru€C~ ~CC(3 if d5 !.~ , .... ~,', v_J , ~ ~ _ -~ ......... 1 (., ,_ ~, .... ,~,"_ ) __ .<._ •• "" __ ~ "",,_, __ , ......... ~ '....-...,..,.. ..... ...,... ~~ .~ • ....,_",,..k,,~ ......... "P"~''''''"~ "-'_'''''-?'' ~ •• -.... ~ ~ ~_ .~. __ ~ .. ~~ •• .>,.-~ft~~" , .... ~-_ ..... ,.,._ ,,~._~ .~ ,,_ ..... ~ "'._~ _'~ •• -,.,.-_~ ~~, f IB Requimments of municipal ordinance authority for suspected source verification testing for midt connections necessary for glllaranteed rights of entry. 1fl®©J (lJ.l fi 1J®1iil'il®fi'ilfi:f§ C({])!S11J:!S1 IB An aggmssive catch basin cleaning prDgram could require a significant capital and O&lY.( , budget. A careful study Df cleaning effectiveness should be undertal<:en befQre increased cleaning is implemented. Catch basin cleaning CDsts are less expensive if vacuum street sweepers are available; cleaning catch basins manually can ClOst approximately twice as much as cleaning the basins with a vacuum attached tQ a sweeper. Gl Methods used fQr illicit cDnnection detectiDn (smQke testing, dye testing, visual inspectiDn, and flDW mDnitoring) can be CDStly and time-cDnsuming. Site-specific factDrs, such as the level QfimperviQus area, the density and ages Dfbuildings, and type Dfland use will determine the levelDf investigatiQn necessary. EncQuraging repQrting Qf illicit discharges by emplDyees can Qffset CDsts by saving expense IOn inspectQrs and directing reSQurceS mDre' efficiently. SDme programs have used funds available frDm "environmental fees" Dr special assessment districts tD fund their illicit connection elimination programs. Ml!Jli7l1ltce1J7J.(llJ.7l1lccce g TwQ-person teams may be required tD dean catch basins with vactQr trucl<:s . 13 Identifying illicit discharges requires teams Df at least tWQ peDple (vDlunteers can be used), plus administrative personnel, depending IOn the cQmplexity Df the storm sewer system. EJ Arrangements must be made fDr prQper disposal Df collected wastes. ~ Requires technical staff to detect and investigate illegal durn,ping viQlatiQns, and tD cQordinate public educatiDn. ' ~M[l)tPJH~Ifim~ll'il1t~H JIfi'il'D"©Ii"fi'il'illIDi!:H©1i'il JFMTf'ti:heY" Dettl!JliiU ({])j'1J:he lEMP Storm Drainflushing Sanitary sewer flushing is a CDmmDn maintenance activity used tQ improve pipe hydraulics and tD remDve pollutants in sanitary sewer systems. The same principles that make sanitary sewer flushing effective can be used to flush storm drains. Flushing may be designed to hydraulically cDnvey accumulated material to strategic IDcatiDns, such as to an Dpen channel, tD anDther point where flushing will be initiated, lOr over tQ the sanitary sewer and on to the treatinent facilities, thus preventing re-suspension and DverflDw Df a pDrtion Df the sDlids during storm events. Flushing prevents "plug flDw" discharges Df cDncentrated pollutant lDadings and sediments. The deposits can hinder the designed CQnveyance capacity of the storm drain system and PQtentially cause backwater cDnditions in severe cases of clDgging. Storm drain flushing usually takes place along segments of pipe with grades that are tDO flat to maintain adequate velocity to keep particles in suspension. .An upstream manhQle is selected to place an inflatable device thai: tempDrarfry plugs the pipe. Further upstream., water is pumped into the line to create a flushing wave. When the upstream reach Df pipe is sufficiently full to i ,.,,_ January 2003 California Storrnwater BMP Handbook Municipal www.cabrnphandbooks.com 50f9 To further reduce the impacts of stormwater pollution, a second inflatable device, placed well downstream, may be used to re-collect the water after the force of the flushing wave has dissipated. A pump may then be used to LTansfer the water and accumulated material to the sanitary sewer for treatment. In some cases, an interceptor structure may be more practical or required to re-collect the flushed waters. It has been found that cleansing efficiency of periodic flush waves is dependent upon flush volume, flush discharge rate, sewer slope, sewer length, sewer flow rate, sewer diameter, and population density. As a rule of thumb, the length of line to be flushed should not exceed 700 feet. At this maximum recommended length, the percent removal efficiency ranges between 65- 75 percent for organics and 55-65 percent for dry weather grit/inorganic material. The percent removal efficiency drops rapidly beyond that. Water is commonly supplied by a water truck, but fire hydrants can also supply water. To make the best use of water, it is recommended that reclaimed water be used or that fire hydrant line flushing coincide with storm drain flushing. Flow Management Flow management has been one of the principal motivations for designing urban stream corridors in the past. Such needs mayor may not be compatible with the stormwater quality /Aals in the stream corridor . • wnstream flood peal{S can be suppressed by reducing through flow velocity. This can be accomplished by reducing gradient with grade control structures or increasing roughness with boulders, dense vegetation, or complex banks forms. Reducing velocity correspondingly increases flood height, so all such measures have a natural association with floodplain open space. Flood elevations laterally adjacent to the stream can be lowered by increasing through flow velocity. However, increasing velocity increases flooding downstream and inherently conflicts with channel stability and human safety. Where topography permits, another way to lower flood elevation is to lower the level of the floodway with drop structures into a large but subtly excavated bowl where flood flows we allowed to spread out. Stream Corridor Planning Urban streams receive and convey stormwater flows from developed or developing watersheds. Planning of stream corridors thus interacts with urban stormwater management programs. If local programs are intended to' control O'r protect dOWT!.1stream environments by managing flows delivered to' the channels, then it is logical that such programs should be supplemented by management of the materials, forms, and uses of the duwnstream riparian corridor. Any proposal for steam alteration or management should be investigated for its potential flow and stability effects O'n upstream, dowl.1.stream, and laterally adjacent areas. The timing and rate of flow from various tributaries can combine in complex ways to alter flood hazards. Each section ..&~hannel is unique, influenced by its own. distribution of roughness elements, management Wvities, and stream responses. I ~ . _"" ~? 6of9 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com January 2003 • • • Flexibility to adapt to stream features <lind behaviors as they evolve must be included in stream reclamation pla:mrring. The amenity and ecology of streams may be enhanced through the landscape design options of 1) corridor reservation, 2) bank treatment, 3) geomorphic restoration, and 4) grade controL Corridor reservation -Reserving stream corridors and valleys to accommodate natural stream meandering, aggradation, degradation, and over bank flows allows streams to find their own fonn and generate less ongoing erosion.. In California, open stream corridors in recent urban developments have produced recreational open space, irrigation of streamside plantings, and the aesthetic amenity of flowing water. Bank treatment -The use of armoring, vegetative cover, and flow deflection may be used to influence a channel's form, stability, and biotic habitat. To prevent bank erosion, armoring can be done with rigid construction materials, such as concrete, masonry, wood planks and logs, riprap, and gabions. Concrete linings have been criticized because of their lack of provision of biotic habitat. In contrast, riprap and gabions make relatively porous and flexible linings. Boulders, placed in the bed reduce velocity and erosive power. Riparian vegetation can. stabilize the banks of streams that are at or near a condition of . equilibrjum. Binding networks of roots increase bank shear strength. During flood flows, resilient vegetation is forced into erosion-inhibiting mats. The roughness of vegetation leads to lower velocity, further reducing erosive effects. Structural flow deflection can protect banks from erosion or alter fish habitat. By concentrating flow, a deflector causes a pool to be scoured in the bed. Geomorpnic restoration -Restoration refers to alteration of distUrbed streams so their form and behavior emulate those ofunrusmrbed streams. Natural meanders are retained, with grading to gentle slopes on the inside of curves to allow point bars and riffle-pool sequences to develop. Trees are retained to provide scenic quality, biotic productivity, and roots for bank stabilization, supplemented by plantings where necessary. A restorative approach can be successful where the stream is already approaching equilibrium. However, if upstream urbanization continues new flow regimes will be generated that could disrupt the equilibrium of the treated system. Grade Control - A grade control structure is a level shelf of a permanent material, such as stone, .masonry, or concrete, over which stream water flows. A grade control structure is called a sill, weir, or drop structure, depending on the relation of its invert elevation to upstream and downstream channels. A sill is inst811ed at the preexisting channel bed elevation to prevent upstream migration of nick points. It establishes a firm base level below which the upstream channel can not erode. A weir or check dam is installed with invert above the preexisting bed elevation. A weir raises the loc81 base level of the stream and causes aggradation upstream. The gradient, velocity,~md erosive potential of the stream channel are reduced. A drop structure lowers the downstream invert below its preexisting elevation, reducing downstream gradient and velocity. Weirs and drop structure control erosion by dissipating energy and reducing slope velocity. January 2003 California Stormwatel" BMP Handbook Municipal www.cabmpi1andboof<s.com 7 of 9 [»~@J0~lJ@~~ ~W~~~lITftJ ~@rnBlJtt~rrn@Gl)~~ .---.,' ,= .. ~-' ,_.__ ~ .->' ••• ~" .. c_, _ "r -_, :.._+«~. _".~., ,~ ~.~ ._ " ~ ... ~...,. ~, _" _~. ~ -'~ ~~.~~~ '-.... ~. '. ><-_ _ ".", _~.~_u,_ ... _ :;l_.~_ J When carefully applied, grade control stmcl-ures can be highly versatile in establishing humi31.ll and environmental benefits in stabilized channels. To be successful, application of grade control structures should be guided by analysis of the SlTealfn system both upstream and downstream from the area to he reclaimed. JEJt:lfJlmp~~~ The California Department of Water Resources began the Urban Stream Restoration Program in 1985. The program provides grant funds to municipalities and community groups to implement stream restoration projects. The projects reduce damages from streambank aid watershed instability arid floods while restoring streams' aesthetic, recreational, and fish and wildlife values. In Buena Vista Park, upper floodway slopes are gentle and grassed to achieve continuity of usable park land across the channel of small boulders at the base of the slopes. The San Diego River is a large, vegetative lined channel, which was planted in a variety of species to support riparian wildlife while stabilizing the steep banks of the floodway. R.efererilt:e~ ~~d Re~@ll.!lr«::~~ Ferguson, RIC 1991. Urban Stream Reclamation, p. 324-322, Journal of Soil and Water Conservation. C geles County Stormwater Quality. Public Agency Activities Model Program. On-line: : ladpw.org/wmd/npdes/public TC.cfm . -, Model Urban Runoff PrQgram: A How-1'10 Guide for Developing Urban Rmioff PrQgrams fQr, Small Municipalities. Prepared by City QfMonterey, City Qf Santa Cruz, California CQastal Commission, Monterey Bay NatiQnal Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. Orange County Stormwater Program http://www.ocwatersheds.com/Storm Water Iswp introduction. asp Santa Clara Valley Urban RunoffPollutiQn Prevention Program. 1997 Urban Runoff Management Plan. September 1997, updated October 2000. San Diego StQrmwater Co-permittees Jurisdictional Urban RunQff Management Program (URMP) Municipal Activities Model PrQgram Guidance. 2001. Project Clean Water. November. United States Environmental Protection Agency (USEPA). 1999. Stormwater Management Fact Sheet Non-stormwater Discharges tQ Storm Sewers. EPA 832-F-99-022. Office of Water, Washington, D.C. September. United States Environmental ProteciionAgency (USEPA). 1999. StQrmwater O&:M Fact Sheet .Ch Basin Cleaning. EPA 832-F-99-on. Office of Water, Washington, D.C. September. 8of9 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com January 2003 • • • tlJ) u!J@j g mJ @1 ~ ~ ~W~)'@:~ ~lJ U¥a @ ~ rft11J:~ ~ @ mil ce~ ' __ " ... _r._'.' ... ~_. _'-__ ..... -.-_"""_"'~""'_"""'~."".~;;:::"'h'~"~~'~''''''''~_'''''''''-' _~,,,,_,,,,,,,,~,,,._,,,~~.>,_,~_,_,-__ , -_____ .. "_ .... _n'_._'= .. ~,~_ United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Illegal Dumping Coutrot On line: hti:p~JVITWW.epa.gQYjnpdes/menuofumps/pon Z.htm United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Storm Drain System Cleaning. On line: http://www.epa.gov /npdes/menuofbmps/poll 16.~tm January 2003 I; I, ; California Stormwater BMP Handbook Municipal www.cabmpl1andbooks.com 90f9 • BMP Sizing Calculation • • To minimize pollutants of concem, we are using: 1. Multiple Systems -The project will utilize a detention basin, swales and inlet inselt to remove sediment, debris, hydrocarbons, oil and grease more effectively. BMPs using different removal processes will be combined to improve overall removal efficiency. (See Fact Sheet TC-60) 2. Bio Clean Curb Basket Sizing for Type B inlet along EI Camino Real-A drainage insert will be used for Structural Treatment BMPs. The drainage insert will be a curb inlet basket to catch debris, with a storm boom (hydrocarbon absorbing ceUulose) to filter hydrocarbons, oil and grease. The drainage insert is a Suntree Technologies mc. product. (See attached manufacturer's information) Based upon Table 3 -Numeric Sizing Treatment Standards, we are using a flow-based BMP designed to mitigate, (infiltrate, filter or treat) the maximum flow rate or runoff produced from a rainfall intensity of 0.2 inches of rainfall per hour for each hour of a storm event. The following calculation shows the maximum amount of flow the insert will be required to treat. To check for adequate capacity of the insert along EI Camino Real, the overall area draining to the inlet, delineated on the attached drainage study was used (i.e. Type B curb inlet). The curb inlet insert is capable of treating the maximum amount of flows produced, furthermore, the insert is capable of treating all flows within Cassia Road and El Camino Real Curb Inlet Insert Max. Area (A) = 5.92 acre C=0.95 Iavg =0.2 inlhr Qavg = C*Iavg* A Qavg = 0.95*0.2*5.92 = 1.12 cfs The curb inlet insert is capable of treating up to 10.6 cfs/3' insert of flow and will be adequate to treat 1.12 cfs average peak runoff. 3. Vegetated swale -Vegetated swales will be used along the northerly and westerly boundaries to direct runoff to the detention basin. (See Fact Sheet TC-30 • • • ~~G"J~Q~~ ~ ~\g~~~~tf1 ~ i2f) Treatment C~ntro~ B Ps 5131 Introdu~t~on This section describes treatment control Best Management Practices (BMPs) to be considered' for incorporation into newly developed public and private infrastructure, as well as retrofit into existing facilities to meet stormwater management objectives. BMP fact sheets are divided into two groups: public domain BMPs and manufactured (proprietary) BMPs. In some cases, the same BMP may exist in each group, for example, media filtration. However, treatment BMPs are typically very different between the two groups. Brand names of manufactured BMPs are not stated. Descriptions of manufactured BMPs in this document should not be inferred as endorsement by the authors. 5.2 Treatment Control BMPs Public domain and manufactured BMP controls are listed in Table 5-1. Table 5=1 Treatment Control BMPs Public Domam Manmacmred (Proprietary) Infilu'ation lInufil1l:l"atimll TC-I0 Infiltration Trench TC-ll Infiltration Basin TC-12 Retention/Irrigation Detention and Settling Detention and Settling TC-20 Wet Pond MP-20 Wetland TC-21 Constructed Wetland TC-22 Extended Detention Basin Biofiltration Biofiltlt"ation TC-30 Vegetated Swale TC-31 Vegetated Buffer Strip TC-32 Bioretention Filtration Filtraition TC-40 Media Filter MP-40 Media Filter Flow Through Separation Flow TIn'ough Separation TC-50 Water Quality Inlet MP-50 Wet Vault MP-51 Vortex Separator MP-52 Drain Inserts Oll:'heli.' o-itheli.' TC-60 Multiple Systems H January 2003 California Stormwater BMP Handbook 5-1 Secf:ioru 5 eatment Control BMPs A BMF fact sheet is a short document that gives aU the information about a particular EMF. Typically each public domain and manufactured EMF fact sheet contains the information outlined in Figure 5-1. The fact sheets also contain side bar presentations with information on EMF design considerations, targeted constituents, and removal effectiveness (ifknown). Treatment BMF performance, design criteria, and other selection factors are discussed in 5.4 -5.6 below. aMP Fact sheets are included in 5.7. rr~~~!fi\IiI/j2>lm ~~®li'il'ilIPJ~® 1F®«;\l: ~Ihl®®tl: JDescri;p-tion California &''Perience Advanta~ Limitations ~ and Sizing Guidelines Performance Siting Criteria Design Guidelines Maintenance Cost References and Sonrces of Additional Information Figure 5-1 Example Fact Sheet Comparing Performance of Treatment BMPs With a myriadrif stormwater treatment BMPs from which to choose, a question commonly . asked is "which one is best". Particularly when considering a manufactured treatment system, .e engineer wants to know if it provides performance that is reasonably comparable to the ~ical public-domain BMPs like wet ponds or grass swales. With so many BMPs, it is not likely that they perform equally for ~l pollutants. Thus, the question that each local jurisdiction faces is which treatment BMPs will it allow, and under what circumstances. What level of treatment is desired or reasonable, given the cost? VVhich BMPs are the most cost-effective? Current municipal stormwater permits specify the volume or rate of stormwater that must be treated, 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 EMP 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 effectivepess comparisons between BMPs problematic. 504" 1 VarHat~on in Performaneel There are several reasons for the observed variation. The V &lJJl."iability of StOK'mwater Quality Stormwater quality is highly variable during a storm, from storm to storm at a site, and between • ·tes even of the same land use. For pollutants of interest, maximum observed concentrations . mmonly exceed the average concentration by a ractor of 100. The average concentration of a storm, known as the event.mean concentration (EMC) commonly varies at a site by a factor Qf 5. One aspect of stormwater quality that is highly variable is the particle size distribution (PSD) of 5-2 California 51:ormwater BMP Handbook 'I!~"') "~'rr-~f'inml?nt and RedevelOflmenl: W8W '" .... January 200~ ( I i \. • • • Section 5 Treatment Conirol BMPs the suspended sediments. This results in variation in the settle ability or these sediments and the pollutants that are attached. For example, several performance studies of nlanufaclllred BMlP's have been conducted in the upper Midwest and Northeast where deicing sand is commonly used. TIle sand, washed off dming spling and summer storms, skews the PSD to larger sizes not commonly found in stormwater f-rom California sites except in mountainous areas. Consequently, a lower level efficiency may be observed if the same treatment system is used in California. l\1[([})§t Field §mm®§ IVl[«})li1l.it@llu T@(\}) ]Few §tOl"Inl.Il§ High variability 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 behveen 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 and difficulty, few studies have monitored enough storms to determine the actual perlormance with a high level of precision. Different D®§lRgnt Clfiiteri.1al. Performance of different systems -vvithin the same group (e.g., wet ponds) differs significantly in part because of differing design criteria for each system. This in turn can make it problematic to compare different groups of treatment BMPs to each other (e.g., wet ponds to vortex separators). . Differimlg imrtltm®IDlit C«JJIDlc®IDlfrn:'atD.€!J)Hl§ rumd Alnlalytical V ~j] .. iability With most treatment' BMPs, efficiency decreases with decreasing influent concentration. This is illustrated in Figure 5-2. TIlUS, a low removal efficiency may be observed during a study not because the device is inherently a poorer peiformer, but possibly because the influent concentrations for the site were unusually low. Also, as the concentration of a particular constituent such as 'fSS 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 .011 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/I..). However, some negative efficiencies observed at higher concentrations may not necessarily be an artifact of laboratory analysis. The cause varies to some extent -,"lith the type of treatment EMP. 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 of leaves that entered the system the previous fall. January 2003 Callfomia Stormwater B~JjP Handbook 5-3 , New Development and Redevelopment 1 I" Section 5 wment Control BMPs J]j)il.f!®Jl~®JffiiJ: M®~:11il(j})rdl~ ([JAr C2ill<emt6rtlll1l~ JEffi<ell®Irll<ey" Researchers (1) have used different methods to calculate efficiency, (2) do not always indicate which method they have used, and (3) often do not provide sufficient information in their report to allow others to recalculate the efficiency using a common method. 100% r";,' ,1t(:'~'ifi' ,.~ ''fu-'~'~'--'''-'-''-~:-'-'''l 80% I c>:' ~X<::;;; '\l '. . ' __ i ,.... .. x';"''6~,,' . ~ 60% I,' 'i.~\>~ ~', -. .. ;:.. 400/! >.~ • g 10 ~(?','i . .fit *' @ 20% ,,; ~ 0% " ~, ~' . , ' , ' :/ ~ SWALE f3I STRIP EDB xSF ~ -20%' ,100,'; ~:2.ilffi. · .. ~oti.~: 46()'.-,~ .. 5&6~~: ·:.~~O ~ '.'.' ',,' I ... 40% x';', • . : ,',,'. '1 ~ -60% l ~ ~ "', ' , : " ' '" ,: 'I )!( WET. BASIN -80% DEl' ,,' .. " ". ,., 'J -100% ------.~-' .-----~-.---.---, One approach to quantifying BMP efficiency is to determine first if the BMP is providing treatment (that the influent and effluent Influent Concentration Figure 5..,2 ~®Ii'ilil@vii:ilB fSffitb:oenlCY V'ersQlls Influent Concentration mean event mean concentrations are statistically different from one another) and then examine I, er a cumulative distribution function of influent and effluent quality or a standard parailel ability plot. This approach is called the Effluent Probability Method. 'While this approach J. s been used in the past by EPA and ASCE, some researchers have experienced problems with the general applicability 'of this method. A discussion of these issues is included in AppendiX B. A second approach to comparing performance among BMPs is to compare effluent concentrations, using a box-whisker plot, the basic form of which is illustrated in Figure 5-3. The plot represents all of the data points, of one study, several studies, or of individual storms, The plots provide insight into the variability of performance within each BMP type, and possible differences in performance among the types. To explain the plot: 50% of the data points as well as the median value of all the data points is represented by the box. That is, the median falls within the 75th and 25th percentile of data (top and bottom of the .box) , The whisker extends to the highest point within a range of 1.5 times the difference between the first and third "'rtiles. Individual points beyond this Ynge are shown as asterisks. r-""-~::.~=~l l .-___ J...-f __ o_f d-,ata points i ! r- Ii Third Quartile ~ ~ ! .:al Median ~:,: i First Quartile ~ I: ! '; , t 1 ! I ~ i-t ~ I r; fi ! r, ~ Whisl<er extends to the'lowest value of data points A line is drawn across the box at the median. The bottom of the box is at the 25th percentile and the top is at tile 75tl1 percentile. The whiskers are the lines that extend from the top and bottom orthe box. f8@J!W[i'~ ~=3 ~©~=WItilH§lke6~ IF>8@'6: 5-4 Califomia stormwater BMP Handbook New Development and Redevelopment January 2003 f'lTrlT'r ,-,,:,I"t'-:--""',:,-,...!~nr.I.(.;' rrv.",. ( • • • Section t5 Treon'ment Control BMPs Recognizing the possible effect of influent concentration on efficiency, an alternative is to compare effluent concentrations. The reasoning is that regardlless of the influent concentration, a particular BMP will generate a narrower range of effluent concentrations. Figure 5-4 shows observed effluent concentrations for several different t}'Pes of BMPs. These data were generated in an eJ..'tensive field program conducted by the California Department of Transportation (Caltrans). As this program is the most extensive effort to-date in the entire United States, the observations about performance in this Handbook rely heavily on these data. The Caltrans study is unique in that many of the BMPs were tested under reasonably similar conditions (climate, storms, freeway stormwater quality), with each type ofBMP sized with the same design criteria. Ari. additional factor to consider when comparing BMPs is the effect of infiltration. BMPs with concrete or metal structures will have no infiltration, whereas the infiltration in earthen BMPs will vary from none to substantial. For example, in the Caltrans study, infiltration in vegetated swales averaged nearly 50%. This point is illustrated with Figure 5-4 where effluent quality of several BMPs are compared. As seen in Figure 5-4, effluent concentration for grass swales is higher than either filters or wet basins (30 vs. 10 to 15 mg/L), suggesting that swales in comparison are not particularly effective. However, surface water entering swales may infiltrate into the ground, resulting in a loading reduction (flow times concentration) that is similar to those BMPs with minimal or no infiltration . 200 r---------------------------------------~--------------_. ~ 180 """ m ..§. 160 c: CD :::I 140 IIi .5 120 :2 '0 100 ti) ~ 80 c ! 60 IJI bl 40 !20 o ~~~------*_--------------~------~-------*------~--~ TC·20 Wet Pond TC·22 EKtended Detention Basin TC·30 TC·31 Vegetated Vegetated Swale Buffer TC·40 Media TC·40 Media TC·40 M"edla Filter (Austin Filter Filter (M ultl" Sand Filter) (Delaware chamber Lineal Sand Treatment Filter) Train) fogl!.!lr~ 5=4 OIbJ!~USlN~©3 ~f(f~IJ.8~Il'il1!; i6@li'il<1::®lfilttB"@i!:u@ll'il§:i ~@B" ~~\f~!i"@jD /D}Hffer~lfilll: ~I!iIMO<1:: tIJi@Il'il'il@OIfil ~1MJ~s January 2003 California StorlTlwater BMP Kandboo!< New Development and Redevelooment " 5-5 Secl:ion 5 ~nentConlfoIBA4PS With equation shown below, it is possible usil1g the data from Figure 5-4 to estimate differel1t levels of loading reduction as a function of the fraction of stormwater that is infiltrated. Where: EEC = the effective effluent concentration I = fraction of stormwater discharged by infiltration EC = the median concen.tration 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 ofTSS 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/1 when the stormwatet reaches the groundwater. This gives: JElEC = (:1l.-({).5j)(3((])) + (<<ll • .\Ji)(.\Ji) = 1l7.5) mmg!L. . .. above value can be compared to other BMPs that may directly produce a lower effluent concentration, but do not exh.ibit infiltration, such as concrete wet vaults. ~t:l4,,2 Oth~r I~$~~~ R~~@lt~d t@ P~rf@rm@'3B1~~ C@mp@)rh~on~ 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 PQllutants 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, P AI-Is, PCBs, and dioxin., With respectto 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 are cadmium, arsenic, silver, chromium, molybdenum, and thallium. Commonly, only the general term "metals" is indicated for a water body vvithout reference to a particular metal. , ~s desirable to knQW hlOw each Qf the treai1.nent BMPs performs with respect tQ the removal Qf ~e above PQllutants. Unfortunately, the perfQrmance data are non-existent or very limited for many IOf the cited pollutants, particularly trash, P AI-fs, PCBs, dioxin, mercury, selenitlm, and pesticides. FurthermlOre, the ClOncentratiQns Qf these constituents are very lQw, often below the 5-6 California Sl:ormwal:er BMP Handbook New Development and Redevelopment January 2003 ( •• '. • Secl:ion 5 Treatment Conirol BMPs detection limit. This prevents the deternJ.ination of which EMFs are most effective. However, "With the exception of trash and possibly dichin, these pollutants readily sorb to s~diments in stormwater and therefore, absent data at this ti1.11e, ean he considered to be removed in proportion to the removal ofTS'§ (i.e., sediment). Therefore, in general, those treatment systems that are most effective at removing TS§ win 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 e:z..1:ended detention basin should be similarly 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 relatiyely small and therefore may have limited storage capacity. Only one manufactured BMP is specifically designed to remove floating 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 propOltion to the removal ofTSS. In contrast, zinc, copper, and cadmium are highly soluble "villi 50% or more in the dissolved phase. Hence, two treatment RMPs may remove T§§ at the same level, but if one is capable of removing dissolved metals, it provides better treatment overall for the more soluble metals. S.,4~3 COmp@jr~~O!l1l~ @f Tf~~tm~1l1t BMP~ f~r N6tlr@g~rr8g g:itr~(:1i' B~~terna, @lB1d 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 efaS is represented in Figure 5-4). Graphs fDr 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 pIlOts, are used by others.) January 2003 California Stormwater BMP Handbook New Development and Redevelopment ."c.~,r, __ ' ... _ .. ~I .. _ ...... _I .. ~ ..... M _ '._ - 5-7 Section 5 .atment Control BMPs --d -m ~ -*' c: (I) :I IIi .~ ;:g E () 1= • • 5-8 14 -----------------------------------. 12 10 '" ,., )i( Ji( B * )i( ~ )X )i( 6 )r )i( )i( 4 2 o~--------------------------------------~----------------------~ Tc.ao Wet Pond TC-22 Elttendad TC-30 Vegetated TC-31Vegetated TC-40 Media Filter (Austin Sand Filter) TC.40 Media Filler (Delaware lineal Sand Flltar) TC-40 Media Fllt.r (rA 0111· chamber Treatment Train) Detention Basin Swale Buffer Figure 5=5 l'@talO NRtll"@gEm OD'D lCffiuenll: 300 ,----------- 250 )K 50 ~ o ~----------------------------~--------~----------------~~ iC-20 Wet Pond iC-22 elttended Detention Basin ie-30 Vegetated Swale TC-31 TC-40 Media iC-40 Media iC-40 Media Vegetated Filter (Austin Filter Filter (M ult!; Buffer Sand Filter) (Delaware chamber Lineal Sand Treatment Filter) Train) fogure ~=«1) 1l@)'ij:;a~ Ii}fis5@Hved ~HIl'll«:: Dim IEffilUlell'llt California StonTIwater BMP Handbook New Development and Redevelopment January 2003 ., .. -' .... rl't"" ..... ' ... -:--'L.. .... ~I".C' ... ~"""'"" ( • 500 2 400 91 :;;J ..... .... t;;: QJ :;;J 300 ~ w .~ Ii: 200 N ! 100 )!( ~ 0 TC·20 Wei Pond • 1,000,000 ..... E CI 100,000 CI .... ~ .S1 10,000 ... c: QJ :::J e w 1,000 .5 Ii) E 100 ~ '0 (J 1J 10 0 1& TC·20 Wet Pond • January 2003 )" " lK )!( )i( TC·22 TC·30 TC·31 TC·40 Media Elttended Vegetated Vegetated Filter (Austin Detention Swale Buffer Sand Filter) Basin Section 5 Treatment Control BMPs lK )K • TC·40 Media TC·40 Media Filter Fliter'(M ultl· (Delaware chamber Lineal Sand Treatment Filter) Train)' fugLIIll"e 5='1 l'@l!:aD Ziuu:: on ~ffh,8ell'ill!: )!( >K )!( * ~ >K )!( ~ TC·22 TC·30 TC·31 TC·40 Media TC·40 Media TC·4D Media Elttended Vegetated Vegetated Filter Filter Filter (M ultl· Detention Swate Buffer (Austin Sand (Delaware chamber Basin Filter) Lineal Sand Treatment Filter) Train) fngl!J.lU"@ ~=~ T@it1§10 Ir~f:~~ ~@HB1f@Il"Ii'ifil§) Ollil ~ffH[jJ.J®llilfb California Stormwater BMP l-landbook New Development and Redevelooment 5·9 Section 5 tjatmeni. Control SMPs '\Nhile a figure is provided fore fecal coliform~ it is impOltant to stress that the performance comparisons betwee1l1 BMPs is problema"!';· Some California EMP studies have shown excellent removal of fecal coliform through con~iTllf~,-ed wetlands and other lBMPs. However, BMP oompmisons are complicated by the fact that several BMPs attract wildlife and pets, thereby elevating bacteria 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 removal between treatment systems it is best to use the parameter total nitrogen. It consists of Total I<;jeldahl 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 Iqeldahl Nitrogen. ~,,4,,4 General P~rf@rm@Irll~® @f M~unjfactured BMPs An important question is how the performance of manufactured treatment BMPs compares to those in 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 ofTSS for the manufactured systems. Data are presented for five general types of manufactured BMPs: wet t ts, draill inserts, constructed wetlands, media filters, and vortex separators. The figures ; . cate wide ranges in effluent concentrations, reflecting in part the different products and . esign criteria within each type. Comparing Figures 5-4 and 5-9 suggests that manufactured products may perform as well as the less effective 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; however, the plot presented 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 hot perform as well as even the least effective public-domain BMPs. This observation is implied by the greater sprea.dwithin some boxes in Figure 5-9, for example, manufactured wet vaults and vortex separators. Product performance within each grouping of manufactured BMPs vary !is follows: . IE] Filters -TSS effluent concentrations range from 2 to 280 mg/L, with a median vi;l]ue of 29 mg/L EJ Inserts -TSS effluent concentrations range from 4 to 248 mg/L with a median value of 27 mg/L o Wetlands -TSS effluent concentrations vary little, and have a median value of 1.2 mg/L • Vaults -TSS effluent concentrations range from 1 to 467 mg/L, with a median value of 36 mg/I.. g Vortex -TSS effluent concentrations nmge from 13 to 359 mg/L, with a median value of 32 mg/L 5-10 California Stormwater BMP Handbook New Development and Redevelopment 4 ........ '," ' .. _ '''-.. '~.., _ ...... _ ........ __ Janual"Y 2003 ( . • • • Section 5 Treatment Coniro! BMPs 800 ~---------.----------'--.'--------.----.----.----------.--------------~ ::::r 700 ~ .i .", 600 !i:: @ :;:! E w 500 .: fffj ~ 400 '0 fit; 'is III 300 "i:j !i:: ~ @ 12. ~ 200 ~ ro I ... January 2003 :i< ~ 100 * .. o ~--==+==------~----~~~~------~---------L-----J M P ·20 Wetland M I' -40 Media Filter M 1'.50 Wet Vault M P ·51 Vortex Separator MP·52 DraIn Inlet figure 5=9 T@ta6 Suspended Solids in ~ffDu~ll'il~ 1,000.0 ,-------------------------------.-------, 100.0 10.0 ., 1.0 0.1 L-_____________________________ ~ ________ ~~ MP-20 We~lai1d I1!l 1"·40 I1!l elllia Filter M P -50 Wet Vault I1!l 1'·51 Vortex Separator I1!l I' -52 Drain Inlet fDguff~ ~=1@ tr@t~n ~l\ll~ir»~1l'il©3~«11 ~@nn@'l~ Hii'll ~1fffHl\ll®ll'ilit (n@!9J=f@fi'm~ll:) -'. 'U.]Pi £ ( ! .'< i California Stormwater BMP Handbook New Development and Redevelopment t rn ~1t., ... ..., r.., ....... ....-'.,--, ,," .I' .. ,.. .. I ~.... .. ...... 5-11 Section 5 .tment Control BMPs iv:, noted earlier, pe:i."formance of particulblI products in a grouping may be due to different design criteria within the group. For example, wet vault pm ducts 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 meCiia. ~B4c~ T~~!hlWt1©~@~y «:~!1"l1:o1fff~@tO@Wfl This Handbook does not endorse proprietary products, although many 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, but only performance data that have been collected following a widely accepted protocol. Protocols have been developed by the American Society of Civil Engineeing (ASCE EMP 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 submit 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 technologies will be proposed (or design criteria for existing technologies will be altered) by development engineers. As with proprietary products, it is advised that new public-domain technologies be considered only if performance data are available and have been collected .wing a widely accepted protocol. Sa5 BMP D~~~gn C!f0t~rma· f~r f~ow ~nd VOhlHl1i8~ 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 stormwater 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 of rainfall intensities at San Jose, California, where most storms have intensities of less than 0.25 in/hr. t patterns at San Jose, California 8 . .re typical of other locations throughout the state. Figures and 5-12 show that as storm sizes increase, the number of events decrease. Therefore, when Ps are designed for increasingly larger storms (for example, storms up to 1 in. versus storms of up to 0.5 in.), the EMP size and cost increase dramatically, while the number of additional 5-12 California Storm water BMP Handbook New Development and Redevelopment l"ln"~1 l"::oh""''''''''''-r,l,nnk;:, roli' January 2003 • • • Section 5 Treatment Control BMPs treated storm events are sm.alll Table 5-2 shows that doubling the design storm depth from 0.50. in. to 1.00 in. only increases the number of events captured by 23%. §imila~ly, doubling the design rainfall intensity from 0.25 in/hr to 0.50 in/Ill' only increases the number of events capt.-ured by 7%. J£I !;;! ~ 1M ~ © 6 (j) n e :I z January 2003 '1200 1067 1000 800 !sOli) 400· 242 200 I 0 ~BlHfi'il ~t@ll"m$ ~~ ~;;m J@~, CA 4l®4So~m)O 113 • 42 -30 5 9 2 1 figure 5=11 fillalDra S1l:@lf'm~ ~t S~tro l@§ell1 CA 3000 ROlill1l Bll1lt@ti1sity at San Jose, CA 2963 19480 2000 iii 2500 .... c ~ UJ :WOO .... 1500 0 '= CIJ 1000 .t::! E :I 500 ~ 0 ~ ~1J ~ ,,~ ~. 207 I!i!iii 10 ~~ '\.~ ~. ~. ~ ~~ ~ ~'Y ~~ 9,335 hourly readings less than 0.10 io/hr are not shown a 'I ~~ ~ "". ",,'P f':J~ '" ~" ~~ "". lRainfaillntensiiy, inches per Hour figure 5=12 fit~OIlil Intelll'ilsnty ii.i1t S~1i'il J@~eD ~A California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 5-1;3 Section 5 Treairnent Control BMPs "if'@l/b)O@ ~=~ Ii.1i'lI~1i"@1filil@1i'lI'i!:@lO 1Jll®~o\GJ1i'lI (Cli'oi!:@li'O@] ~~ ~i!:@li"lffiil~ jjfi"@@lt@@~ @.Ill: ~@.Ifi'il dJ@~@LT (CIA jp'Jl"illlJi1lilll§e~ N1!llIIT!1llhleJl"illlf lillll<Clt'®IIT!1lellllitffili lIlill<crl'eIIT!1lelillit~ JH[ii§il:m.'li<c~ lEw®IDlR§ ][lilllCf£'®ffi§® lilill ][lilllCli"etilS lllill lillMlP' Ji))e§lignll ']['ug®il: iirm llimg® iDle§llglDl Cri1l:lSili$l §1l:illllt'IIT!1l§']['li"leffi1l:ti::<rll Storm Depth 1,067 0.00 to 0.50 in. +100% +23% Storm Depth 242 0.51 to 1.00 in. Rainfall Intensity 2,963 0.10 to 0.25 infhr +100% +7% Rainfall Intensity 207 0.26 to 0.50 infhr Due t~ economies of scale, doubling the capture and treatment requirements for a BMP are not likely to double the cost of many BMPs, but the incremental cost per event will increase, making increases beyond a certain point generally unattractive. Typically, design criteria for water quality control BMPs are set to coincide with the "knee of the curve," that is, the point of inflection where the magnitude of the event increases more rapidly than number of events _ured. Figure 5-13 shows that the "knee of the curve" or point of diminishing returns for San , California is in the range of 0.75 to 1.00 in. of rainfall. In other words, targeting design storms larger than this will produce gains at considerable incremental cost. Similar curves can be developed for.rainfall intensitY and runoff volume. • 5-14 R~Hf(j) ~~@Ii"ms Qlt San J@$fe9 CA 1600 "U ®~=~@(D@ 1200 '1000 800 I} "Knee of the Curve" is in this vicinity ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~. ~. 1\' 1\' ~' 'V "!ll' ~. 1),. II,' ~, ~. !j;)' (t\l. ~. ~t@Il"IrIlillQ)@bQ)tIhl9 Rf(j)~Ihl@~ IFHgjllJlli'e ~=J!.~ R@sO"u ~'d:@Ii'Il1fil~ ©~ §~ff1l ]©~@u CA California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • Section /5 Treatment Control BMPs It is iIrnpor'mnt to note that arbitrarily targeting large, :infrequent storm events can actually reduce the pollutant removal capabilities of some BMPs. This occurs when outlet structures, 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 quicldy 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 hI'S, 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 curve" or point of diminishing returns. 5,,[5 .. 1 Vohjme"'Ba$~d BMP Design Volume-based BMP design standards apply to BMPs whose primruy 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 whose composite runoff coefficient is in the 0.50 to 0.95 range. . . The following are examples of volume-based EMP 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: . GJI Eighty (80)% ofthe 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. m The maximized stormwater 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. Ctallif©rnia St©rmWtalit<eIf BMP lBIa1lJlulb@ok.AppF'@alich The volume-based EMF sizing methodology included in the first edition of the Californ.ia Storm Water Best Management Practice Handbook (Stormwater Quality Task Force, 1993) has been included in this second edition of the handbook and is the method recommended for use. January 2003 California Stormwater BMP Handbook New Development and Redevelopment , , t' 5-15 Section 5 .. ai-merit Control BMPs The California StOf".!11water lBMP Handbook approach is based on results of a continuous simulation model, the STORM model, de>~'"'loped by the Hydrologic Engineering Center of the U.S. Army Corps of Engineers (COE-HEr ,,977). 'The Storage, Treatment, Overflow, Runoff Model (STORM) was applied to long-term hourly rainfall data at numerous sites throughout California, with sites selected throughout the state representing a wide range of municipal stormwater permit areas, climatic areas, geography, and topography. STORM translates rainfall into runoff, then routes the runoff through detention storage. The volume-based BMP sizing curves resulting from the STORM model provide a range of options for choosing a BMP sizing curve appropriate to sites in most areas of the state. The volume-based BMP sizing curves are included in Appendix D. Key model assumptions are also documented in Appendix D. 100 90 80 70 If 60 c ::s Ill: : ' .• ... 50 -CI ?ft i 40 . ::II i 30 (J . 20 10 0 0.0 0.1 Sall'i J@sa (1821) • Santa lCiaU"OiI County. CalOfofi01!Ba ~. " 0.2 Ca tu I sis 24·hr Drawdown =Runoff Cosffieisn\ = 0.25 =Runoff Cosffieient = 0.50 : =Runoff Coefficient = 0.75 =Runoff Coefficient = 1.00 0.3 0.4 0.5 0.6 0.7 Unit Basin Storage Volume (Inches) O.S 0.9 1.0 figure 5=14 «::~lPlttlJ.lr~/TB"eatmeB'llt Analysis at San J@se, CA The California Stormwater BMP Handbook approach is simple to apply, and relies largely on commonly available information about a project. The following steps describe the use of the BMP sizing curves contained in Appendix D. 1. Identify the "EMP 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. Calculate the composite runoff coefficient "C" for the area identified in Step 1. • Select a capture curve representative of the site and the desired drain down time using. See Appendix D. Curves are presented for 24 hour and 48 hour draw dowl1 times. The 48 hour curve should be used in most areas of California. Use of the 24 hour curve should be limited 5-16 California Stormwater BMP Handbook New Development and Redevelopment HlHIIH1'I, r'""~h,~nh-;:.nr4hnnf(<:i rnlT' January 2003 ( ( • Section 5 TreainroentCorDuolBA4Ps to dramage areas with. coarse sons that readily settle and to watersheds where warming may be detrimental to downstream fisheries. Draw down times iIll excess of 48 hOUES should!. be used with caution as vector breeding can be a problem afcer water has stood in excess Df 72 hours. 4. Determine the applicable requirement for capture of runoff (Capture, % of RunDff). 5. Enter the capture curve selected in Step 3 on the vertical axis at the "Capture, % Runoff' value identified in Step 4. Move horizontally to the right across capture curve until the curve corresponding to the drainage area's cDmposite runDff CD efficient "C" determined in Step 2 is intercepted. InterpDlation between curves may be necessary. MDve vertically dDwn the from fDr this point until the hDrizDntal axis is intercepted. Read the "Unit Basin StDrage VDlume" along the hDrizontal axis. If a local requirement fOil' capture Df runDff is nDt specified, enter the vertical ruds at the "knee Df the curve" fDr :the curve representing cDmpDsite runDff . CD efficient "C." The "knee of the curve" is typically in the range Df 75 tD 85% capture. 6. Calculate the required capture vDlume of the BMP by multiplying the "BMP Drainage Area" frDm Step 1 by the "Unit Basin StDrage VDlume" frDm Step 5 tD give the BMP vDlume. Due tD the mixed units that result (e.g., ac-in., ac-ft) it is recDmmended that the resulting vDlume be cDnverted tD cubic feet fOil' use during design. Urban Runoff Quality Management Approach The vDlume-based BMP sizing methodology described in Urban R1J.noff Quality Management (WEF Manual of Practice ND. 23/ ASCE Manual Df Practice ND. 87, (1998), pages 175-178) has been included in this edition of the handbDok as an alternative to the CalifDrnia StDrmwater BMP HandbDDk apprDach described abDve. The Urban RunDff Quality Management ApprDach is suitable fDr planning level estimates Df the size Df volume-based BMPs (WEF / ASCE, 1998, page 175). The Urban RunDff Quality Management approach is similar to the CalifDrnia StDrmwater BMP HandbDDk apprDach in that it is based Dn the translatiDn of rainfall tD runDff. The Urban RUnDff Quality Management approach is based Dn twD regressiDn equatiDns. The first regressiDn equatiDn that relates rainfall tD runDff. The rainfall tD runDff regressiDn equatiDn was develDped using 2 years of data frDm mOire than 601 urban watersheds natiDnwide. The secDnd regression equatiDn relates mean annual runoff-producing rainfall depths tD the "Maximized Water Quality Capture VDlume" which cDrrespDnds tD the "knee Dfthe cumulative prDbability curve". This secDnd regressiDn was based Dn analysis DflDng-term rainfall data frDm seven rain gages representing climatic zones acrDSS the cDuntry. The Maximized Water Quality Capture VDlume cDrrespDnds to approximately the 85th percentile runoff event, and ranges frDm 82 tD 88%. The twD regression equatiDns that fDrm the Urban RunDff Quality Management approach are as fDllDWS: • C = 0.858i3 -0.78i2 + O.774i + 0.04 Po = (a e C) 0 P6 January 2003 California Stormwater BMP Handbook New Development and Redevelopment 'MH}nM rp~""""I1"!t,r......":"",,,A~~,...,.'1'''''' ... -- 5-17 SectionS fi8J~ment Control BMPs Where C = runoff coefficient i = watershed imperviousness ratio which is equal to the percent total imperviousness divided by 100 Po = Maximized Detention Volume, in watershed inches a = -regression constant, a=1.s82 and a=1.963 for 24 and 48 hour draw down, respectively P6 = mean annual runoff-producing rainfall depths, in watershed inches, Table #-1. See AppendixD. The Urban Runoff Quality Management Approach is simple to apply. The following steps describe the use of the approach. 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 . •• Calculate the "Watershed Imperviousness Ratio" (i), which is equal to the percent of total impervious area in the "EMF Drainage Area" divided by 100. . 3. Calculate the "Runoff Coefficient" (C) using the following equation: C = 0.858i3 -0.78i2 + 0.774i + 0.04 4. Determine the "Mean Annual Runoff" (F6)for the "BMP Drainage Area" using Table #-1 in AppendixD. 5. Determine the "Regression Constant" (a) for the desired BMP drain down time. Use a=1.582 for 24 hrs and a=1.963 for 48 hr draw down. 6. Calculate the "Maximized Detention Volume" (Po) using the following equation: Po = (a e C) e P6 7· Calculate the required capture volume of the BMP by multiplying the "EMP Drainage Area" from Step 1 by the "Maximized Detention Volume'~ from Step 6 to give the BMP volume. Due to the mixed units that result (e.g., ac-in., ac-ft) it is recommended that the resulting volume be converted to ft3 for use during design. ~1l~lll Flow=Ba~~d BMP De~ig~ Flow-based BMP design staJl1dards apply to BMPs whose primary mode of pollutant removal depends on the rate of flow of runoff through the EMP. Examples of BMPs in this category 5-18 ...". M ..... California Storm water BMP liandbook New Development and Redevelopment IMIMIn/ ~1'Ji:lm"himgbooks.com January 2003 • •• Section 5 Treatment Control BMPs indudes swrues, §aI!lld ruters, screemng deviices, and many pmprietary products. TypicaID!y, a flow~based ]EMF design criteria calls for the capture and inrutration or treatment of the flow runoff' produced by r:ain events IDf a specified magnitude. The following are examples IDf flow-based EMF design standards fTom current municipal stormwater permits. The permits require that flow-based BMPs be designed to captQ.re and then to infiltrate or treat stlOrmwater runoff equal to one of the folloWing: ~ 10% of the 50-yr peak flow rate (Factored JFlood Flow Approach) o The flow of rullloff produced by a ram event equal to at least two times the 85th percentile hourly rainfall intensity foJ!' the applicable area, based on historical records of hourly rainfall depths (California Stormwater EMP Handbook Approach) El The flow of runoff resulting from a rain event equal to at least 0.2 in/hr intensity (Uniform Intensity Approach) 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 . The three typical requirements ShOWlll above all have in common a rainfall intensity element. That is, each criteria is based treating a flow of runoff produced by a rain event of specified 'rainfall intensity. . In the first example, the Factored Flood Flow Approach, the design rainfall intensity is a function of the location and time of concentration of the area discharging to the BMP. The intensity in ,this Cl;lse is determined using Intensity-Duration-Frequency curves published by the flood control agency with jurisdiction over the project or available from climatic data centers. This approach is simple to apply when the 50-yr peak ,flow has already been determined fQr either drainage system design or flood control calculations. In the second example, the California Stormwater BMP Handbook Approach (so called because it is recommended in this handbook), the rainfall intensity is a function of the location of the area discharging to the EM]? The intensity in this case can be determined using the rain intensity cumulative frequency curves developed for this Handbook based on analysis of long- term hourly rainfall data at numerous sites throughout California, with sites selected throughout the state representing a wide range of municipal stormwater permit areas, climatic areas, geography, and topography. These rain intensity cumulative frequency curves are inclUded in Appendix D. This approach is recommended as it reflects local conditions throughout the state. The flow-based design criteria in some municipal permits require design based on two times the 85th percentile houdy rainfalll intensity. The factor of two included in these permits appears to be provided as a factor of safety: therefore, caution shlOuld be exercised when applying • additional factors of safety during the design process so that over design can be avoided. 1"'5. 2',· _. -,0. __ F· Je'lOuary 2003 Califomia Stormwater BMP Handbool{ New Development and Redevelopment 5-19 Sectiora 5 .tment Contml BMPs In the third example, the Uniform KJl1tensity Appmach, the rall1.fal!X intensity is specified directly, and is not a functilOn IOf the location or lime of concentration of the area draining to the EMF. 'This approach lis very simple to apply, but it is not reflective of local! conditions. The three example flQw-based EMP design criteria m'e 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 follQws: Q=CiA where Q = flQW in ft3/s i = rain intensity in in/hr A = drainage area in acres C = runQff cQefficient • RatiQnal Formula is widely used for hydrologic calculations, but it dQes have a number of itations. FQr stormwater BMP design, a key limitatiQn is the ability Qf the RatiQnal FQrmula tQ predict runoff frQm undeveloped areas where runoff cQefficients are highly variable with stQrm intensity and antecedent mQisture conditions. This limitatiQn is accentuated when predicting runQff frQm frequent, small stQrms used in stQrmwater quality BMP design because many Qf the runQff cQefficients in CQmmon use were develQped fQr predicting runQff fQr drainage design where larger, infrequent stQrms are Qf interest. Table 5-3 prQvides SQme general guidelines, IOn use Qf the RatiQnal EquatiQn. ll"i:llble 5=31 USl® @f R~tH@Ililr:ilR !F@Il"Il'il'ilIl.BDiID f@1l" §t@ll'lMlWClter BMP Design Composite Runoff Coefficient, "C" EMF Drainage A1rellJ! 1{)).1{))1{))il:1{)) 1{)).~5) 1{)).~6 ibm 1{)).5@ @.5ill. to 0.75 1{)).76 to t.1{))1{) (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 eummary, the Rational FQrmula, when used with commonly tabulated runoff coefficients in undeveloped drainage areas, wiU likely result in predictions higher than will be experienced uThder actual field conditioThs. However, given the simplid:cy of the equation, its use remains ! A t .. " $ w ~) ?_ 5-20 California Stormwater BMP I-Iandbook !\lew Development and Redevelopment -. ~. . ,. " . e-;~- • • • Secf:lon !j TreaimentConi"rof BMPs practical and is ofteli"D. the st8JD.dard method specified by locallagendes. In generall, use of allternative formu.las for predicting BMF design :flows based on the intensity criteria above IS acceptable if the formula is approved 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 'GBMP Drainage Area" that drains to the proposed BMP. This includes all areas that win contribute runoff to the proposed EMP, 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 Flood 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 the 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. California Stormwater BMP Handbook Approach: Select a rain intensity cumwative frequency 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 t.he "EMP Design Flow" a. Factored Flood Flow Approach: Using the ":EMP 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 BMP 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 "BMF Design ~low." c. Uniform Intensity Approach: Using the GGBMP Drainage Area" from Step 1, the "Design Rainfall Intensity" from Step 2C, and 'GC" from Step 3, apply the Rational Formula. The result is the "BMP Design Flow." I .. f ... ~!f" 4,,.... 4;Z*Ui, n,," .,' 1$ __ , -~ ....... January 2003 ---; :' .' -~ -: -__ • r _._ • _ :; '"' California Stormwater 8M!=' I-/andbool< New Development and Redevp'nnlYlPI'I!" SeciuorD 5 .imeni Control BMPs ~(J~(J~ (C@[j'[fi]@O~~@~ ~@~o..Jjm~=~@J~~@ @J1l'iJ©l fO@\'M=~@H~@@] ~Bifr11fY fQ)~~B~rru Volume-based BMPs and flow-based BMPs do not necessarily treat precisely the same stormwater runoff. For example~ an Oln-line volume-based EMP such as a detention basin will treat the design runoff volume and is essentially l.maffected by runOlff entering the basin ~t an extremely high rate, say from a very short, but intense storm that produces the design volume of runoff. However, a flow-based BMP might be overwhelmed by the same short, but intense storm if the storm intensity results in runoff rates that exceed the flow-based EMF design flow rate. By contrast, a flow-based EMF such as a swale will treat the design flow rate of runoff and is essentially unaffected by the duration of the design flow, say from a long, low intensity storm. However, a volume-based detention basin subjected tOl this same rainfall and runoff event will begin to provide less treatment or will go into bypass or overflow mode .after the design runoff volume is delivered. Therefore, there may be some situations where designers need to consider both volume-based and flow-based BMP design criteria. An example of where both types of criteria might apply is an off-line detention basin. For an off-line detention basin, the capacity of the diversion structure could be designed to comply with the flow-based BMP design criteria while the detention basin itself could be designed to comply with the volume-based criteria . • en both volume-based and flow based criteria apply, the designer should determine which of the criteria apply to each element of the lB~P system, and then size the elements accordingly. Other BMP Selec:tion Factors Other factors that influence the selection of BMPs include cost, vector control issues, and endangered species issues. Each of these is discussed briefly below. 5m6s1 Costs The relative costs for implementing various public domain and manufactured BMPs based on flow and volume parameters are shown in Tables 5-4 and 5-5 below: 'ifabie ~=4 ~e@till@m9{! ir~M@ S=~ E@;olu;limne Compcgll"ASOn Matrix . Comparo!§@1l'll Matrox: = fH@'W Strip $$ Swale $$ Wet Vault Not available Media Filter $$$$ Not available Not available = VohAms BMP Austin Sand Filter Basin Delaware Lineal Sand Filter Extended Detention Basin CEDB) Multi Chamber Treatment Train (MCIT) Wet Basm Manufaci-ured Wetland Infiltration Basin Wet Pond and Constructed Wetland 5-22 California 5tormwater 8MP Handbook New Development and Redevelopment . ~, . .. Costl aCJl'e-ft $$$$ $$$$ $$ $$$$ $$$$ Not availahle $ $$$$ January 2003 • • ~o~o~ W®~t@[f' ~lf'®®@l~!ru~ C@mil~D@l~f@)itO@fll~ Section 5 Treatment Control BMPs The potential of a BMP to create vector breeding habitat and/or harborage should be considered when selecting BlViPs. Mosquito and other vector production is a nuisance and public health threat. Mosquitoes can breed in standing water almost immediately fonowing a EMP installation and may persist at unnaturally high levels and for longer seasonal periods in created habitats. BMP siting, design, construction, and maintenance must be considered in order to select a BMP that is least conducive to providing habitat for vectors. Tips for minimizing vector breeding problems in the design and maintenance of BMPs are presented in the BMP fact sheets. Certain EMPs, including ponds and wetlands and those designed with permanent water sumps, vaults, and/or catch basins (including below-ground installations), may require routine inspections and treatments by local mosquito and vector control agencies to suppress vector production. 5a6s3 Threaten~d gand Endangered Species Considerations The presence or potential presence of threatened and endangered species should also be considered when selecting BMPs. Although preservation of threatened ,endangered species is crucial, treatment EMPs are not intended to supplement or replace species habitat except under special circumstances. The presence of threatened or endangered species can hinder timely and routine maintenance, which in turn can result in reduced BMP performance and an increase in vector production. In extreme cases, jurisdictional rights to the treatment BMP and surrounding land may be lost if tp.reatened or endangered species utilize or become established in theBMP. When considering BMPs where there is a presence or potential presence of threatened or endangered species, early coordination with the California Department of Fish and Game' and the U.S. Fish and Wildlife service is essential. During this coordination, the purpose and the long-term operation and maintenance requirements of the BMPs need to be dearly established through written agreements or memorandums of understanding. Absent firm agreements or understandings, proceeding with BMPs under these circumstances is not recommended. BMP fact sheets for public domain and manufactured BMPs follow. The BMP fact sheets are individually page numbered and are suitable for photocopying and inclusion in stormwater quality management plans. Fresh copies of the fact sheets can be individually downloaded from the Caltrans Stormwater EMP Handbook website at www.cabmphandbooks.com . S!£"-r ... ·e· "2 J_~'''''_ ¢--_ ... ',,-~~:::;:, _)'"'~>-~...-.._.c .~ .... _u • :::1 •• ",,--:) ..... ,... _*' .. ;O"Rifp ........ <K-"'-"'-'-'>i .... aSif&f.'li-r·x .. __ ..... w .. · ... t· .... ;g""''''''%/S% ; ..... _.:o;:;;::;;:za: .. +JS.'F@fiP4¥?Po.". • ..,. .... Gif "'c .or ...... " ....... *** +?El January 2003 California Stormwater BMP Handbook 5-23 New Development and Redevelopment www.cabmphandbooi<s.com • • • D@J$~1i"6[p)thjHfil Dry extended detention ponds (a.k.a. dry ponds, extended detention basins, detention ponds, extended detention ponds) are basins whose outlets have been designed to detain the stormwater runoff from a water quality design storm for some minimum time (e.g., 48 hours) to allow particles and associated pollutants to settle. Unlike wet ponds, these facilities do not have a large permanent pool. They can also be used to provide flood control by including additional flo?d detention storage. «::~8Bf'@If'Il'ilU@.l ~XtpJ(gllf'fl@lIl'il«:::@ Caltrans constructed and monitored 5 extended detention basins in southern California with design drain times of 72 hours. Four of the basins were earthen, less costly and had substantially better load reduction because of infiltration that occurred, than the concrete basin. The Caltrans study reaffirmed the flexibility and performance of this convention81 technology. The small headloss and few siting constraints suggest that these devices are . one of the most applicable technologies for stormwater treatment. Ad 'W @.llrnt@.l ~ ~§j o Due to the simplicity of design, extended detention basins are relatively easy and inexpensive to construct and operate. ffi Extended detention basins can provide substantial capture of sediment and the toxics fraction associated with particulates. ['J Widespread application with sufficient capture volume can provide significant control of channel erosion and enlargement caused by changes to flow frequency relationships resulting from the increase of impervious cover in a watershed. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbook.col11 o Tributary Area EI Area Required o Hydraulic I-lead "ii"~Ii"®ctllte@.] ~@Ii:il~'ttD\ttlJ.l@Ii'il1l:~ .f Sediment .& if' Nutrients @ .! Trash [)j .f Metals fA if' Bacteria L2. if' Oil and Grease t::, if' Organics ~ l@g@i1lol (Removal Effectiveness). @ Low A Medium ~ High ~(i@Jrrllil!l~'ll'o>J(i@1? @MOilU~ ~@J(GaOiI't1a@fiil 1 of 10 .u Ulfil ofb@)U:o@~41~ m Limitation of the diameter of tlhe orifice may not allow use of extended detention in watersheds ofless than 5 acres (would require an orifice with a diameter ofless than 0.5 inches that would be prone to dogging). ~ Dry extended detention ponds have only moderate pollutant removal when compared to some other structur~l stormwater practices, and they are relatively ineffective at removing soluble pollutants. [3 Although wet ponds can increase pmperty values, dry ponds can actually detract from the value of a home due to the adverse aesthetics of dry, bare areas and inlet and outl~t structures. [Q)®~H@1l1l @!i'il©~ ~U;(i:;UIfil@) ~l!J.lu@~~fluU'i)~~ III Capture volume determined by local requirements or sized to treat 85% of the annual runoff volume. o Outlet designed to discharge the capture volume over a period of hours. Length to width ratio of at least Jl..5:Jl. where feasible. Basin depths optimally range from 2 to 5 feet . • Include energy dissipation in the inlet design to reduce resuspension of accumwated sediment. . f3 A maintenance ramp and perimeter access should be included in the design to facilitate access to the basin for maintenance activities and for vector surveillance and control. III Use a draw down time of 48 hours in most areas of California. Draw down times in excess of 48 hours may result in vector breeding, and should be used only after coordination with local vector control authorities. Draw down times ofless than 48 hours should be limited to BMF drainage areas with coarse soils that readily settle and to watersheds where warming may be determined to downstream fisheries. r.e@fi'il~f(:If'Y(b:t:hjlll1l/ltlfll~Itll~«:fd@1l1l ce@ti'il~U©1~Hf'@lil:9@1l1l~ [) Inspect facility after first large to storm to determine whether the desired residence time has been achieved, EJ When constructed 'with small tributary area, orifice sizing is critical and inspection should verify that flow through additional openings such as bolt holes does not occur. 1P>®l1r'~@lf'm©.! Ii'il(i;~ One objective of stormwater management practices can be to reduce the flood hazard associated with large storm events by reducing the peak flow associated with these stOJt'ms. Dry extended detention basins can easily be designed for flood control, and this is actna i1y the primary purpose of most detention ponds . ., extended detention basins provide moderate poUuta~t removal, provided that the recommended design features are incorporated. Although they can be effective at removing 2 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • some pollutants through serding, they are less effective at removing soluble pollutants because of the absence of a permanent pooL Several studies are available on the effectiveness of dry extended detention ponds including one recently concluded by Caltrans (2002). TIle load reduction is greater than the concentration reduction because of the substanti2l1 infiltration that occurs. Although the infiltration of stormwater is dearly beneficial to surface receiving waters, there is the potential for groundwater contaJl11ination. Previous research on the effects of incidental infiltration on groundwater quality indicated that the risk of contamination is minimal. There were substantial differences in the amount of infiltration that were observed in the earthen basins during the Caltrans study. On average, approximately 40 percent of the runoff entering the unlined basins infiltrated and was not discharged. The percentage ranged from a high of about 60 percent to a low of only about 8 percent for the different facHities. Climatic conditions and local water table elevation are likely the principal causes of this difference. The least infiltration occurred at a site located on the coast where humidity is higher and the basin invert is within a few meters of sea level. Conversely, the most infiltration occurred at a facility· located well inland in Los Angeles County where the climate is much warmer and the humidity is less, resulting in lower soil moisture content in the basin floor at the beginning of storms. Vegetated detention basins appear to have greater pollutant removal than concrete basins. In the Caltrans study, the concrete basin exported sediment and associated pollqtants during a number of storms. Export was not as common in the earthen basins, where the vegetation appeared to help stabilize the retained sediment. ~fi'ij;Hlfil\9J «::WU't!:®1f'8@l Dry m .. 1:ended detention ponds are among the most widely applicable stormwater management practices and are especially useful in retrofit situations where their low hydraulic head requirements allow them to be sited within the constraints of the eJdsting storm drain system. In addition, many communities have detention basins designed for flood controL It is possible to modify these facilities to incorporate features that provide water quality treatment and/or chan,nel p:iJotection. Although dry eil.i:ended detention ponds can be applied rather broadly, designers need to ensure that they are feasible at the site in question. This section provides basic guidelines for siting dry extended detention ponds. In general, dry extended detention ponds should be used on sites with a minimum area of 5 acres. With this size catchment area, the orifice size can be on the order of 0.5 inches. On smaller sites, it can be challenging to provide channel or water quality control because the orifice diameter at the outlet needed to control relatively small storms becomes veIY sm2l11 and thus prone to clogging. In addition, it is generally more cost-effective to conuollarger drainage areas due to the economies of sC81e. Extended detention basins can be used with almost all soils and geology, iNith minor design. adjustments for regions of rapidly percolating soils such as sand. In these areas, extended detention ponds may need an impermeable liner to prevent ground water contamination. The base of the extended detention facility should not intersect the water table. A permCl.li1ently wet bottom may 7oecome a mosquito breeding ground. Research in Southwest Florida (Santana et al., 1994) demonstrated that intermittently flooded systems, such as dry extended detention January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmpl1andbook.com 3 of 1.0 . . endS, produce more mosq[uitoes than other pond syste:ms, particularly when the facilities ren1.a:i.ned wet for Anore than 3 days foHowing heavy rainfalL A study in Pdnce George's County, Maryland, found that stormwater management practices can increase stream temperatures (Galli, 1990). Overall, dry extended detention ponds increased temperature by about 5°F. In cold water streams, dry ponds should be designed to detain stormwater for a relatively short thne (i.e., 24 hours) to minimize the amount of warming that occurs in the basin. ~@l@lnfi:fi@ll1l@ln [Jl@l~fi@)1i'il ~llJ.IH@l@lflfill1l~~ In order to enhance the effectiveness of extended detention basins, the 'dimensions of the basin must be sized appropriately. Merely providing the required storage volume "Win not ensure maximum constituent removal. ]By effectively configming the basin, the designer "Will create a long flow path, promote the establishment of low velocities, and avoid having stagnant areas of the basin. To promote settling and to attain an appealing environment, the design of the basjn should consider the length to width ratio, cross-sectional areas, basin slopes and pond configuration, and aesthetics (Young et al., 1996). Energ-y dissipation structures should be included for the basin inlet to prevent resuspension of accumulated sediment. The use of stilling basins for this purpose shou.ld be avoided because the standing water provides a breeding area for mosquitoes. Extended detention facilities should be sized to completely capture the water quality volume. A ~ropool is often recommended for inclusion in the design and one is shown in the schematic ~gram. These smalll permanent pools greatly increase the potential for mosquito breeding and complicate maintenance activities; consequffitly, they are not recommended for use in California. A large aspect ratio may improve the performance of detention basins; consequently, the outlets should be placed to maximize the flowpath through the facility. The ratio of flowpath length to width from the inlet to the outlet should be at least 1.S:1 (L:W) where feasible. ]Basin depths optimally range from 2 to 5 feet. The facility's drawdown time should be regulated by an orifice or weir. In general, the outflow strucllue should have a trash rack or other acceptable means of preventing clogging at the entrance to the outflow pipes. The outlet design implemented by Caltrans in the facilities constructed in San Diego County • <", ; " " '. _", 1 '."-. '-')" , used an outlet riser with orifices. . . d t ..11' 1 ti. t ~~{@]Iiil'iliP'~~ @'if ~A[U:®f1il@J®@J 1Ql®U:®f1il11:0@[J'i! ({i)1W1l:0®il: ~"Ii"IW«::ii:lWu<>@ 1Iif! 0 ullSC!llarge 1118 wa "er ~J1.ty volume, and the riser overflow height was set to the design stOlm elevation. A stainless steel screen was placed 4 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • around the outlet dser to ensure that the orifices would not hecome dogged with debris. Sites either used a separate riser or hroad crested weir for overflow of runoff for the 25 and greater year storms. A picture of a typical outlet is presented in Figure 1. The outflow structure should be sized to allow for complete drawdown of the water quality volume in 72 hours. No more than so% of the water quality volume should drain from the facility within the first 24 hours. The outr1ow structure can be fitted with a valve, so that discharge from the basin can be halted in case of an accidental spill in the watershed. §WlmmlOlN'YJ @fDl2Sig7J11. RI.Z~@mme7J11.iJl.IOlttU.([JJ7J11.$ (1) Facility Si~ing -The required water quality volume is determined by local regulations or the basin should be sized to capture and treat 85% of the annual n,moffvolume. See Section S.5.1 of the handbook for a discussion of volume-based design. (S) Basin Configuration - A high aspect ratio may improve the performance of detention basins; consequently, the outlets should be placed to maximize the flowpath through the facility. The ratio of fIowpath length to width from the inlet to the outlet should be at least 1.S:1 (L:W). The flowpath length is defined as the distance from the inlet to the outlet as measured at the surface. The width is defined as the mean width of the basin. Basin depths optimally range from 2 to 5 feet. The basin may include a sediment forebay to provide the opportunity for larger particles to settle out. A micropool should not be incorporated in the design because of vector concerns. For online facilities, the principal and emergency spillways must be sized to provide 1.0 foot of freeboard during the 2s-year event and to safely pass the flow from loo-year storm. . Pond Side Slopes -Side slopes of the pond should be 3:1 (H:V) or flatter for grass stabilized slopes. Slopes steeper than 3:1 (H:V) must be stabilized with an appropriate slope stabilization practice. Basin Lining -Basins must be constructed to prevent possible contamination of groundwater below the facility. Basin Inlet -Energy dissipation is required at the basin inlet to reduce resuspension of accumulated sediment and to reduce the tendency for short-circuiting. Outflow Structure -The facility's drawdo"Wll time should be regulated by a gate valve or orifice plate. In general, the outflow structure should have a trash rack or other acceptable means of preventing dogging at the entrance to the outflow pipes. The outflow structure should be sized to allow for complete drawdown of the water quality volume in 72 hours. No more than 50% of the water quality volume should drain from the facility within the first 24 hours. The outflow structure should be fitted with a valve so that discharge from the basin can be halted :in case of a.n accidental spm in the watershed. This same valve also can be used to regulate the rate of discharge from the basin. . The discharge through a control orifice is calculated from: January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmDhandbook.com . 5 of 10 • (6) where: Q = discharge (ft3/ s) C = orifice coefficient A = area of the orifice (ft2) g = gravitational constant (32.2) H = water surface elevation (ft) Ho= orifice elevation (ft) Recommended values for Care 0.66 for thin materials and .0.80 when the matel1al is thicker than the orifice diameter. This equation can be implemented in spreadsheet form with the pond stage/volume relationship to calculate drain time. 1'0 do this, use the initial height of the water above the orifice for the water quality volume. Calculate the discharge and assume that it remains constant for approximately w minutes. Based on that discharge, estimate the total discharge during that interval and the new elevation based on the stage volume relationship. Continue to iterate until H is approximately equal to Ho. When using multiple orifices the discharge from each is summed. Splitter Box -When the pond is designed as an offline facility, a splitter structure is used to isolate the water quality volume. The splitter box, or other flow diverting approach, should be designed to convey the 25-year storm event while providing at least 1.0 foot of freeboard along pond slide slopes. (7) Erosion Protection at the Outfall-For online facilities, special consideration should be given to the facUity's outfall location. F'lared pipe end sections that discharge at Or near the stream invert are preferred. The channel immediately below the pond outfall should be modified to conform to natural dimensions, and lined with large stone riprap placed over filter doth. Energy dissipation may be required to reduce flow velocities from the primary spillway to non-erosive velocities. (8) Safety Considerations -Safety is provided either by fencing ofllie facility or by managing the contours of the pond to eliminate dropoffs and other hazards. Earthen side slopes should not exceed 3:1 (H:V) and should terminate on a flat safety bench area. l.andscaping can be used to impede access to the facility. The primary spillway opening mUlst not permit access by small children. Outfall pipes above 48 inches in diameter should be fenced. . IM@lH!FilIt~ll'il@jH'il(b;~ Routine maintenance activity is often thought to consist mostly of sediment and trash and debris removal; however, these activities often constitute only a small fraction of the maintenance hours. During a recent study by Caltrans, 72 hours of maintenance was performed annually, but only a little over 7 hours was spent on sediment and trash removal The largest recurring activity was vegetation management, routine mowing. The latgest absolute number of hours was associated with vector control because of mosquito breeding that occurred in the _~mng basins (example of standing water to be avoided) installed as energy dissipaters. In most ~ses, basic housekeeping practices such as removal of debris accumulations and vegetation management to ensure that the basin dewaters completely in 48-72 hours is sufficient to prevent creating mosquito ali.1d other vector habitats. j -- 6 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmohandbooks.com January 2003 • • • Consequently, ma:IJ.ltenance costs should be estimated based plimarily on the mowing frequency and the time required. Mowing shonJ!ld be done at least annually to avoid establishment of woody vegetation, but may need to be performed much more frequently if aesthetics are an important consideration. Typical activities and frequencies include: !3 Schedule semiannual inspection for the beginning and end of the wet season for standing" water, slope stability, sediment accumulation, trash and debris, and presence of burrows. EJ Remove accumulated trash and debris in the basin and around the riser pipe during the semiannual inspections. The frequency of this activity may be altered to meet specific site conditions. ~ Trim vegetation at the beginning and end of the wet season and inspect monthly to prevent establishment of woody vegetation and for aesthetic and vector reasons. III Remove accumulated sediment and regrade about every 10 years or when the accumulated sediment volume exceeds 10 percent of the basin volume. Inspect the basin each year for accumulated sediment volume. C@st C@7l!$ttTnIl~ti.@n C@~1i: The construction costs associated 1Nith extended detention basins vary considerably. One recent study evaluated the cost of all pond systems (Brown and Schueler, 1997). Adjusting for inflation, the cost of dry extended detention ponds can be estimated with the equation: where: C = Construction, design, and permitting cost, and V = Volume eft3). Using this equation, typical construction costs are: $ 41,600 for a 1 acre-foot pond $ 239,000 for a 10 acre-foot pond $ 1,380,000 for a 100 acre-foot pond Interestingly, these costs are generally slightly higher than the predicted cost of wet ponds (according to Brown and Schueler, 1997) on a cost per total volume basis, which highlights the difficulty of developing reasonably accurate construction estimates. In addition, a typical facility constructed by Caltrans cost about $160,000 with a capture volume of only 0.3 ac-ft. An economic concern associated with dry ponds is that they might "detract slightly from the value of adjacent properties. One study found that dry ponds can. actually detract from the perceived va1u~ of homes adjacent to a dry pond by between 3 and 10 percent (Emmerling- Dinovo, 1995). January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbook.com 7 of 10 "@i1i1UZ"<1:?11Mll17M~<1:? C@~tj: FlOr plOnds, the annual ClOst IOf routine maintenance is typically estimated at abDut 3 tD 5 percent IOlfthe constructilOn ClOst (EPA website). Alternatively, a cDmmunity C1:Ul estimate the ClOst Dfthe maintenance activities outlined in the maintenance section. Table 1 presents the maintenance CDsts estimated by Caltrans based IOn their eJ..rperience with five basins IDeated in sDuthern CalifDrnia. Again, it shDuld be emphasized that the vast majDriry Dfhours are related tD vegetation management (mDwing). rrab~e 1 ~~li::~Ii'll'il~rti:~@.l ~~ISlfi"IID\W1Sl AIl'ilIl'ilIl).j~H MaJHIi'ilf!:~I!'lI~li'illt:e Eff@irll: Arowity JLmlID(j))]l" 1H[(j))1UI.I!."§ E([)l1Uli]p>JlJlll(f)lllrll: &: C(j))§it Mm1!:eD."Mn1l ($) Inspections 4 7 183 Maintenance 49 126 2282 Vector Control 0 0 0 Administration 3 0 132 Materials 535 535 ']['(j))1i:aill 5)6 $668 $3,13~ •ef~r«~Hi'il(;~~ @]fad S@ll,Ijr(;~~ @ff A@.l@lHtO@!i'il@lO iliBf@ll"matR@1l'll flOwn, W., and T. Schueler. 1997. The Economics of Storm water BMPs in the Mid-Atlantic Region. Prepared for Chesaperuce Reseall'ch ClOnsortium. Edgewater, MD. Center for Watershed Protection. EllicDtt City, MD. Denver Urban Drainage and FllOod ContrDI District. 1992. Urban Storm Drainage Criteria Manual-Volume 3: Best Management Practices. Denver, CO. Emmerling-Dinovo, C. 1995. Stonnwater Detention Basins and Residential Locational Decisions. Water Resources Bulletin 31(3): 515-521 Galli, J. 1990. Thermal Impacts Associated with Urbanization and Stormwater Management Best Management Practices. Metropolitan Washington Council of Governments. Prepared for Maryland Department Df the Environment, Baltimore, MD. GKY, 1989, Outlet Hydraulics of Extended Detention Facilities fDr the NDrthern Virginia Planning District CDmmission. . MacRae, C. 1996. Experience from MDrphDlogical Research on Canadian Streams: Is Control IOf the Two-Year Frequency Runoff Event the Best Basis fDr Stream Channel Protection? In Effects o/Watershed Development and Management IOn Aquatic Ecosystems. American Society Df Civil Engineers. Edited by L. Roesner. Snowbird, ill. pp. 144-162. Maryland Dept of the Environment, 2000, Maryland StlOrmwater Design Manual: Volumes 1 & prepO'1..red by MDE and Center for Watershed ProtectilOn. 8 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • Metzger, M. E., D. F. Messer, C. L Beitia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side Of StOl'IDwater Runoff Management: Disease Vectors Associated With Structural BMPs. Stoll'nlwater 3(2): 24-39. Santana, F., J. Wood, R. Parsons, and S. Chamberlain. 1994. Control of Mosquito Breeding:in Permitted Stormwater Systems. Prepared for Southwest Florida Water Management District, . Brool~viUe,FL. . Schueler, T. 1997. Influence of Ground Water on Performance of Stormwater Ponds in Florida. WatershedProtection Techniques 2(4):525-528. Watershed Management Institute (WMI). 1997. Operation, Maintenance, and Management of Stormwater Management Systems. Prepared for U.S. Environmental Protection Agency, Office of Water. Washington, DC. Young, G.K., et al., 1996, Evaluation and Management of Highway Runoff Water Quality, Publication No. FHWA-PD-96-032, U.S. Department of Transportation, Federal Highway Administration, Office of Environment and Planning. Infonna.ti.on Res(})u?ces Center for Watershed Protection (CWP), Environmental Quality Resources, and Loiederman Associates. 1997. Maryland Stormwater Design Manual. Draft. Prepared for Maryland Department of the Environment, Baltimore, MD. Center for Watershed Protection (CWP). 1997. Stormwater BMP Design Suppl~mentfor Cold Climates. Prepared for U.S. Environmentali. Protection Agency, Office of Wetlands, Oceans and Watersheds. Washington, DC. U.S. Environmental Protection Agency (USEPA). 1993. Guidance Specifying Management Measuresfor Sources of Non point Pollution in Coastal Waters. EPA-840-B-92-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC. January 2003 California Stormwater. BMP Handbook New Development and Redevelopment www.cabrnphandbook.com PM?- 9 of 10 • • 10 of 10 ANTI-5EEP COLLAR or FILTER DIAPHRAGM • • -•. ' ",' z . C~lif~r~i~ St~;'m~~t~r~ BM'p 'i~~~db~Ok New Development and Redevelopment www.cabmphandbooks.com ~EMERGENCV SPILLWAY PLAIN "BleW January 2003 • • • ~~~]~f1@tt~@ ~~@~® I ..... ~ _~._.~" •... rd ... __ ~ ~ __ , .. <" t .. :; '''''''~''~' ,. _~ ... , • __ ...... ~""., ,< ¥ -., .. eO ~ ..... ~ -_ • ..., ~~..,.~, ~ .... J.~ ~.::;J._._~ . ..,. ~_,~ ,_"" "'" ...... ~ [»~~efFfipto@tl'il Vegetated swales are open, shallow channels with vegetation covering the side slopes and bottom that collect and slowly convey mnoff flow to downstream discharge points. They are designed to treat runoff through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Swales can be natural or manmade. They trap particulate pollutants (suspended solids and trace metals), promote infiltration, and reduce the flow velocity of stormwater runoff. Vegetated swales·can serve as part of a stormwater drainage system and can replace curbs, gutters and storJ;n sewer systems. <i:@lBH'if@fFfi'ilH@.l ~J[IPl~[J"n~Ifil~~ Caltrans constructed and monitored six vegetated swales in southern California. These swales were generally effective in reducing the volume and mass of pollutants in runoff. Even in the areas where the annual rainfall was only about 10 inches/yr, the vegetation did not require additional irrigation. One factor that strongly affected performance was the presence of large numbers of gophers at most of the sites. The gophers created earthen mounds, destroyed vegetation, and generally reduced the effectiveness of the controls for T§§ reduction. ~©1w@] [jjJt@]@l®~ GJ If properly designed, vegetated, and operated, swales can serve as an aesthetic, potentially inexpensive urban development or roadway drainage conveyance measure with significru::ri: coUateral water quality benefits. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 8 Tributary Area Cll Area Required ITI Slope El Wa£er Availability 1F@[f'~®'il:®©J (C@Iii1~\l:n1l:!!ll®Iii1'il:~ ~ Sediment A ~ Nutrients 0 ~ Trash e ~ Metals fA ~ Bacteria e ~ Oil and Grease fl ~ OrganiCS &. lL®g®i1l1ill (Rem@v£J1 EWectiveness) @ Low & Medium ~ High ~~@Ii'WilW.w@lf @1Jl1G\lUfi~ ~3@(SilG\l~n@D1J 1 of 13 • Roadside ditches should be regarded as significant potenti<JIl swalejbuffer strip sites and should be utiHzed for tlllis purpose whenever possible, OJ 1i'U'il ~'tl:@'j'~o @fiil ~ a Can be difficult to avoid channelization, B May not be appropriate for industrial sites or locations where spills may occur 8! Grassed swales cannot treat a very large drainage area, Large areas may be divided and treated using multiple swales, !B A thick vegetative cover is needed for these practices to function properly, El They are impractical in areas with steep topography. ILl They are not effective and may even erode when flow velocities are high, if the grass cover is not properly maintained. £] In some places, their use is restricted by law: many local municipalities require curb and gutter systems in residential areas. o Swales are mores susceptible to failure if not properly maintained than other treatment lBMPs. a~u@1ro C§J!fil@J ~O~O!fil@ @Mfi@J~n~!fil~t§) IT] lFlow rate based desigII. determined by 10cOil requirements or sized so that 85% of the annual runoff volume is discharged at less than the design rainfall intensity. 1'3 Swale should be designed so that the water level does not exceed 2/3rds the height ofllie grass or 4 inches, which ever is less, at the design treatment rate. 1'3 Longitudinal slopes should not exceed 2.5% !D Trapezoidal channels are normally recommended but other configurations, such as parabolic, can also provide substantial water quality improvement and may be easier to mow than designs with sharp breaks in slope. GI Swales constructed in cut are preferred, or in fiU areas that are far enough from an adjacent slope to minimize the potential for gopher damage. Do not use side slopes constructed of fill, which are prone to structural damage by gophers and other burrowing animals, Ibl A diverse selection oHow growing, plants that thrive under the specific site, climatic, and watering conditions should be specified, Vegetation whose growing season corresponds to the wet season are preferred. Drought tolerant vegetation should be considered especially for swales that are not part of a regularly irrigated landscaped area. o The width of the sW2l1e should be determined using Manning's Equation using a v8i.lue of • 0.25 for Manning's n. 2 of 13 California Stormwater BMP !-Iandbool< New Development and Redevelopment www.cabl11phandbooi<s.com January 2003 • • • \W~COl~~@tt~©~ ~W@j~~ u(6ao:33@ , __ " ,-,~, R ..... --.-~-., , ~~~-"-' <,.~-"" .... -. "-~,,,,,,_''''''''T''~ -".,-..-,.--~ "'-'-. , ·"3,'~'.~'-~~_' _. __ z::,_ ~ __ ·.-t_~~.·c" <,-,-'-" ~"'~-" -:-.. ~-.~ --,--4 ..... ~-,~,---·-3 C(jJJ811§1i:TJ"ll1l~rdIfJJTfilllmJfPce~fiiIfJJTfil CIfJJTfil&SR@Ycen"(f)ltJiIfJJTfil&S o lndude directions in the specifications for use of appropriate fertilizer and soil amemlments based on soil properties determined through testing and compared to the needs of the vegetation requirements. fJ Install swales at the time of the year when there is a reasonable chance of successful establishment without irrigation; however, it is recognized that rainfall in a given year may not be sufficient and temporary irrigation may be used. Cl If sod tiles must be used, they should be placed so that there are no gaps between the tiles; stagger the ends of the tiles to prevent the formation of channels along the swale or strip. E;! Use a roller on the sod to ensure that no air pockets form between the sod and the soil. o Where seeds are used, erosion controls will be necessary to protect seeds for at least 75 days after the first rainfall of the season. lPerformanc:e The literature suggests that vegetated swales represent a practical and potentially effective technique for controlling urban runoff quality. While limited quantitative performance data exists for vegetated swales, it is known that check dams, slight slopes, permeable soils" dense grass cover, increased contact time, and small storm events all contribute to successful pollutant removal by the swale system. Factors decreasing the effectiveness of swales include compacted soils, short runoff contact tJim.e~ large storm events, frozen ground, short grass heights~ steep slopes, and high runoff velocities and discharge rates. Conventional vegetated swale designs have achieved mixed results in removing particulate pollutants. A study performed by the Nationwide Urban Runoff Program (NURP) monitored three grass swales in the Washington, D:C.~ area and found no significant improvemen,t in urban runoff quality for the pollutants analyzed. However, the weal{ performance of these swales was attributed to the high flow velocities in the swales~ soil compaction, steep slopes, and short grass height. Another project in Durham~ NC~ monitored the performance of a carefully designed artificial swale that received runoff from a commercial parking lot. The project tracked 11 storms and concluded that particulate concentrations of heavy metals (Cu, Pb, Zn~ and Cd) were reduced by apprmdmately 50 percent. However~ the swale proved largely ineffective for removing soluble nutrients. The effectiveness of vegetated swales can be enhanced by adding check dams at approximately 17 meter (50 foot) increments along their length (See Figure 1). These dams maximize the retention time within the swale, decrease flow velocities~ and promote particulate settling. Finally, the incorporation of vegetated filter strips parallel to the top of the channel banks can help to treat sheet flows entering the swale. Only 9 studies have been conducted on all grassed channels designed for water quality Cfable 1). The data suggest relatively high removl:ll rates for some pollutants, but negative removals for some bacteria~ and fair perfmmance for phosphorus. I, p, January 2003 "C~lif~rni; Sto~;;;;at~; BMP' i-Iandb~;!~·'" . New Development and Redevelopment www.cabmphandbooks.com _.~, -'_. - ' I 3 of 13 y~=~@ ~~@1~~@t1:~(QJ ~~@a~ f ;z:.~ •• __ ., _ ~"_ ~" , _ -..Flt,-_""'_ro", '_'_~'~" ~..,.r"",-,_,_ , •• _ ..... , ____ ................. __ .,,_$ _ ....... _ "'......,_~. r ,,, _ .~ _~ '" ... _..,..~ • __ ~ ___ ••• _·1 .... __ , ' .. ' __ ,~-" • ___ • t." ."" • . __ .'2"'<'1 • ¥@iQ)U® J1, ~Ii"@§i§i®~ §iW@U® blJl@flOrY.Jil:@Ii'i1\1: 1]"®!ffiil@W@H ®ffffcCl;U®UilCl;W <9J@il:@ ~<ellll1l([llv8lllllEjfl1id_<eli1llCii<e1§l (% R®llll1l([llv8llll) §itIUl«lly 'JI'§§ 'JI'lil' 'lIN NOs M<ei!:8llll1§l 1Bl~ICi!:",mi~ 'lI'yJpl® Caltrans 2002 77 8 67 66 83-90 -33 dry swales Goldberg 1993 67·8 4·5 -31-4 42-62 -100 grassed channel Seattle Metro and Washington 60 45 --25 2-16 -25 grassed channel Department of Ecology 1992 Seattle Metro and Washington 83 29 --25 46-73 -25 grassed channel Department of Ecology, 1992 Wang et aI., 1981 80 - - -70-80 -dryswale Dorman et al., 1989 98 18 -45 37-81 -dryswale Harper, 1988 87 83 84 80 88-90 -dryswale Kercher et al., 1983 , dryswale 99 99 99 99 99 - Harper, 1988. 81 17 40 52 37-69 -wetswale Koon, 1995 67 39 -9 -35 to 6 -wetswale ernIe it is difficult to distinguish between different designs based on the small amount of available data, grassed channels generally have-poorer removal rates than wet and dry swales, although some swales appear to export soluble phosphorus (Harper, 1988; Koon, 1995). It is not clear why swales export bacteria. One explanation is that bacteria thrive in the warm swale soils. Siting Criteria The suitability of a swale at a site will depend on land use, size of the area serviced, soil type, slope, imperviousness of the contributing watershed, and dimensions and slope of the swale system (Schueler et al., 1992). In general, swales can be used to serve areas ofless than 10 acres, with slopes no greater than 5 %. Use of natural topographic lows is encouraged and natural drainage courses should be regarded as significant local resources to be kept in use (young et al., 1996). Selection Crite.,i,([[t (NCTC([)G~ 1I.<g)<g)3) ~ Comparable performance to wet basins EI Limited to treating a few acres f!l Availability of water during dry periods to maintain vegetation El Sufficient available land area • search in the Austin area indicates that vegetated controls are effective at removing pollutants en when dormant. Therefore, irrigation is not required to maintain growth during dry periods, but may be necessary only to prevent the vegetation f-rom dying. 4 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmpnandbooks.com January 2003 • • • \W~~~tc@l1t~©J ~~~~~ 1F(c=~© •.... ",r-55 ~-,-".~ ~ '-<'~"-'<'~'~~"~'."~;'('''-''-''-~---'~'''''<--'''-~ -----.. ~.~--~.," ... ~"~,~,, ." ~--,,-< .... , .. -'. -,.'-~'--'-'-"~' ~~~'~-~' •• ~--~-----~.--•• "'-~-•• ~ >~ .. -.--! The topography of the site should permit the design of a channel WiLh appropriate slope and cross-sectional area. Site topography may also dictate a need for addit:i.on3l] structural controls. Recommendations for longitudinal slopes range between 2 and 6 percent. Flatter slopes can be used, if sufficient to provide adequate cOlJ-veyance. Steep slopes increase flow velocity, decrease detention time, and may require energy dissipating and grade check Steep slopes also can be managed using a series of check dams to terrace the swale and reduce the slope to within ' acceptable limits. The use of check dams with swales also promotes infiltration. AddHti@lfil~g D~$i@1lil ~fl,lJg~®Ogllil~~ Most of the design guidelines adopted for swale design specify a minimum hydraulic residence time of 9 minutes. This criterion is based on the results of a single study conducted.in Seattle, Washington (Seattle Metro and Washington Department of Ecology, 1992), and is not well supported. Analysis of the data collected in that study indicates that pollutant removal at a residence time of 5 minutes was not significantly different, although there is more variability in that data. Therefore, additional research in the design criteria for swales is needed. Substanti~ pollutant removal has also been observed for vegetated controls designed solely for conveyance (Barrett et al, 1998); consequently, some flexibility in the design is warranted. Many design guidelines recommend that grass be frequently mowed to maintain dense coverage near the ground surface. Recent research (Colwell et al., 2000) has shown mowing frequency or grass height has little or no effect on pollutant removaL §-n.n.mm([Jl1J1!f ofJ!)e&ig;1ro. R.e~l[})mme1ro.rd([Jlttll.1[})1ro.$ 1) The swale should have a length that provides a minimum hydraulic residence time of at least 10 minutes. The maximum bottom width should not exceed 10 feet unless a dividing berm is provided. The depth of flow should not exceed 2/3rds the height of ' the grass at the peak of the water quality design storm intensity. The channel slope should not exceed 2.5%. 2) A design grass height of 6 inches is recommended. 3) Regardless of the recommended detention time, the swale should be not less than 100 feet in length. 4) The width of the swale should be determined using Manning's Equation, at the peak of the design storm, using a Manning's n of 0.25. 5) The swale can be sized as both a treatment facility for the design storm and as a conveyance system to pass the peak hydraulic flows of the too-year storm if it is located "on-line." The side slopes should be no steeper than 3:1 (H:V). 6) Roadside ditches should be regarded as significant potential swalejb4ffer strip sites and should be utilized for this purpose whenever possible. If flow is to be introduced through curb cuts, place pavement slightly above the elevation of the vegetated areas., Curb cuts should be at least 12 inches wide to prevent clogging. January 2003 Swales must be vegetated in order to provide adequate treatment of runoff, It is important to maximize water contact with vegetation. and the soil surface. For general purposes, select fine, dose-growing, water-resistant grasses. If possible, divert runoff (other than necessary irrigation) during the period of vegetation _1 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 5 of 13 y~~~~@jt1:®©J ~~~G~ ~ ~ --,~, 5 • h •• , ... ~ ~~ "0'" >->-...--,¥_, ..... ~ ... 0" ,,--<,.,-._.-_~. ~ '~C"""---P ,-.C ~;;. ~ , .. ,.J • establishment. W11ere nmoff d.iversion is not possible, cover graded ,and seeded areas with suitable elL'Osion control materials. IMl@lHIl'ila:~Il'il@lIfil(G~ The useful life of a vegetated swale system is d.irectly 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 fer1:ilizers and p~sticides 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 sewer at an approved discharge location. Residuals (e.g., silt, grass cuttings) must be disposed in accordance with local or State requirements. Maintenance of grassed swales mostly involves .raintenance of the grass or wetland plant cover. Typical maintenance activities are ~mmarized below: o 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. G 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 Oll" to suppress weeds and woody vegetation. D 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. EJ 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 . • 6 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com "t",,, January 2003 • • • ~@~1l; C([J/ii7J.9j,.[iu-ozw.~ttil.(Q)1!1l. C(Q)$1J: Little data is available to estimate the difference in cost between various swale designs. One study (§WRPC, 1991) estimated the construction cost of grassed channels at approximately $0.25 per ft2. This price does not include design costs or contingencies. Brown and Schueler (1997) estimate these costs at apprmdrnately 32 percent of construction costs for most stormwater management practices. For swales, however, these costs would probably be significantly higher since the construction costs are so low compared with other practices. A more realistic estimate would be a total cost of approximately $0.50 per ft2, which compares favorably with other stormwater management practices . JanuarY 2003 C~'iif;~~-;~St~~;';'';;'ater BMP H~ndb~ok New Development and Redevelopment www.cabmphandbooks.com 7oft3 "IT'C=~@ 't7egetClteEdi ~\Wl* =e. ",.,'" .. .....,NilAA ,$%, fi+i!!EC.we' '_M!iiiIiiii\ '\ "".'W_,We<R,_ ... e Wi ... Iii>i,,,i19hfp""**lI ........ ,,'?\iW,,,,,,,, "\" ", , [f'(§)~~® :2 ~w~D® (C@stl: ~~tl:nm~te (~EWRPCu :!l.9~:!l.~ --~~~--.......... W-'.'. Ui!itCo~t G~Q9~u~e~ ~ llEUiit ~ ettent U i.t)W o IMMlerate Hfgb low r~~ili1z2i1:iIJ!'iI $ ~ Swa!!IJ 'I 1 ~ $107 ~ $214 $441 $107 [)\llmobi~2atioi'lmUght Site) Prepar.atlcn C1S!iii'W!g!l< ................ §i#:3e. ' 0.5 $2,200 ~.OOO I $5;400 $1.100 elubbirlgl .............. ~:'mJJ 0.25 $3,000 I $5,20@ $a.ooo $!!l50 Gef1~l"ai , ytjl 312 $2.10 $3.70 $5,~ $1~1 E'm'il!\l8No~ •• ~ •••••• ,. ~~! I:!lM TiIlO" ...... ~ YI!J2 . 1,210 ~.20 $O.~ $OSJ $242 -'fI'''''-';';''~ .. n' .. -~ .. =.-"i ~~ [)~~!@pfl'l~nt ~rag9d Topsoil Yd'2 H '1,210 00.40 $UlO $1.001 fi$..~4 r Sf:lsd, Illll!t'l f~~r .. I $o~ •••• " ••..•••• " ...... YfJ,a 1,210 $1.20 ~.<W $s.ao $1.4l52 . , . $lJi1i1~@ta'l --~m -. --$5.11$ I' -~ --=\ CQntiflSOOW$ $wlille 1 25% ~5% 25% $1,219 I, $6U95 t C;'199'1} ---'''---'-,-'--'--'-'~------------.-~-----.----.--.~------.----.-- NmGr. i'l/lgbirtmon/demobillzration refers m the mganRoo and p!afifling inVOl\l'etim esl:ablisltlrlg e vegetative swale. . fJ Swaiet~as a bottom 1.viiJth of U) 'foot, a top width of 10 feet with 1:3 $ide !SlOpes, and a 1$ifiOQ..foot length. !l< Ama (!Ioored :::: (top v.,qdth ... '10 feet) x swale length. ~ Itfe~ gll.!lfObet:i ::: (top width j( m.vsle length). eVO~Mme excavated ::: (O.e1 x top 'av!dth x S\va!e depth}:It swale length (parabolic cf(:.m-secUon). (j) Ar~ til~:::: (top width? BfsvIsfe depil'!2) x swale lengih (pnbolle croo&-sedion). 3{to~ ~ Area seeded ::: :area cl~red x 0.5. Ii AreliJ sodded ::: area cloored x IIL5. -~~~ Tota~C@st - MIi)~er~e $214 $~.900 ~~1tVO $'i,300 $1,Stitll $1,316 $'I,ifll12 $424 $6~~ ~..-.,.,.;.; ~ " $~,~'HlI $1.eg~ $2,904 $4,3$~ $@.~ $1~.~fli1ij -. , .. '" , $2,341 ~,41$ M~~ $11.ns $nJ),'l~ .. .u.« j\;~f i3 ' s "eww ~, '!<ih@_HiI ......... Wi California Stormwaters'iOip Handb:r' b!\3 ,1Ui5 ""'S'h" ¥,'.". F;&,,; F" j~nuarY 2003' New Development and Redevelopment www.cabmr·-·.1dbooks.com ,Y,letated Swale .. ___ ... """, " ,',.,., • • 1rtC=~@ iJ'&ll!blU® ~ ~stam~u:ed M1clililf!l1!:eIl'1lJll'ilce Costs (SEWRPCu 1991 ~ G(i)fil®l'~~ laWI'ii Caw ~wai@ O®b«i", f3!1~ utter ~mO\i'2U ~rrmss Rl'lSGsd1rig;J with ~Jlulciu lBl'1d !4,wiHizsr \t'rogram AdmlnisimHol'I wnci ~wale 11flSJ)9rniol'l T>frtall ~.oo 11,000 ~~'ysali' W. 'i0 16iismr flOOr l'fjemf $O.SOI yG2 $0.151 flnaer foot I year, plus $251 fnspeclion SWaieSize (Depth and Top Width) d v .. _ .. ___ .. ---P""""':J -..... -I U'oot i!)(;pt~ 3..foot foot Bottom Widlhj Bottom 'Md~ 21 .. Foot '1ft.~tmt Tim Width Top Width .. $O.21/linelllrfoot iII:JliIiIIQI __ S •• II!/RII:d $O.181Ilnaarfr.d .00.28 iOnearfoot ~.10 IUll'lGarfoot $0:10 ifinsarfoot iIO,01II1n":J $0.(11 nmr.arfooi $0.15 I Billearfoot $1J.15/llnearfoct $8.53IIRli9ari'olllt $ (t.7li lBinear foot W'ili~~~ ~ If Ii. II.. §H ,~.i.W5<........ *1"'''' +*' "ria" #iAiW3iRii+¥¥ f!li!L'P+""ffi'i'iI!iiiIfi£ ikvfQ~c' _._ January 2003 California Stormwater BMP Handbook 9 of 13 New Development and Redevelopment IM\AUAI ,...~f..t.t"II"l .... t....." .... ...!!.... .......... i ... ___ _ V~~~tt@1t~~ ~~@1lD~ , __ ~. __ ~, ~ ~ ._ ,;(~~_ ....... "~ "" ,,~~~ 0$_,-,.., .v_ ...... "'-·, ~_ .. ~ _. ,,_ u_ ... "',..~ __ +_ ._<. _ I 111I(jJf:ll.7I1!.ttrE7I1!.@7I1!.~rE C@3iJ: . Caltrans (20l0l2) estimated the expected annual maintenance cost for a swale with a tributary area of approximately 2 ha at approximately $2,70l0l. Since almost all maintenance consists of mowing, the cost is fundamentally a function of the mowing frequency. Unit costs developed by SEWRPC are shown in Table 3. In many cases vegetated channels would be used to convey runoff and would require periodic mowing as wen, so there may be little additional cost for the water quality component. Since essentially all the activities are related to vegetation management, no special training is required for maintenance personnel. R~fereWll(';e~ «:ilfiul S@~I"«::~~ @f ~@l«Ufto@Il1l@~ ilfllf@rmatm@n'il Barrett, Michael R, Walsh, Patrick M., Malina, Joseph F., Jr., Charbeneau, Randall J, 1998, "Performance of vegetative controls for treating highway runoff," ASCE Journal of Environmental Engineering, Vol. 124, No. 11, pp. 1121-1128. Brown, W., and T. Schueler. 1997. The Economics of Stormwater BMPs in the Mid-Atlantic Region. Prepared for the Chesapeake Research Consortium, Edgewater, MD, by the Center for Watershed Protection, Ellicott City, MD. Center for Watershed Protection (CWP). 1996. Design of Stormwater Filtering Systems. Prepared for the 'Chesapeake Research Consortium, Solomons, MD, and USEPA Region V, Chicago, IL, by the Center for Watershed Protection, Ellicott City, MD . • well, Shanti R., Homer, Richard R., and Booth, Derek lB., 200l0. Characterization of . ~formartce Predictors and Evaluation of Mowing Practices in Biofiltration Swales. Report to King County Land And Water Resources Division and others by Center for Urban Water Resources Management, Department of Civil and Environmental Engineering, University of Washington,Seattle, WA Dorman, M.E., J. Hartigan, RF. Steg, and T. Quasebarth.1989. Retention, Detention and, Overland Flow jor Pollutant Removal From Highway Stormwater Runoff. Vol. 1. FHWA/RD 89/202. Federal Highway Administration, Washington, DC. Goldberg. 1993. Dayton Avenue Swale Biofiltration Study. Seattle Engineering Department, Seattle, W A. Harper, H. 1988. Effects of Stormwater Management Systems on Groundwater Quality. Prepared for Florida Department of Environmental Regulation, Tallahassee, FL, by Environmental Research and Design, Inc., Orlando, FL. Kercher, W.C., J.C. Landon, and R. Massarelli. 1983. Grassy swales prove cost-effective for water pollution control. Public Works, JL6: 53-55. Koon, J. 1995. Evaluation of Water Quality Ponds and Swales in the Issaquah/East Lake Sammamish Basins. King County Surface Water Management, Seattle, WA, and Washington Department of Ecology, Olympia, W A. etzger, M .. R, D. F. Messer, C. L. laeitia, C. M. Myers, and V. L. Kramer. 20l0l2. The Dark Side Stormwater Runoff Management: Disease Vectors Associated With Structural laMPs. Stormwater 3(2): 24-39.0akland, P.H. 1983. An evaluation of stormwater pollutant removal .•• 5 •.. 4 -,\-, 10 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 • • • '¥7~~®il(§)'lt~(Q~ $)\yVff@:1~~ IfQC=~@ j~.,~ ... _-.... ,.-z-,~" .... ., ____ ',--,,_ ",,.,., __ ~~.,, ••. ,,,~ .,,, •• ,,,.~r_"<}~_'N._ •• G5 ~_'_~'.r _~' __ ........ ~,",~ ....... _ .. __ ",,,_,_.~,. ___ '",_ ..... -~ __ v~ t_,_~·",'_ .. ,,-·_·~<-<·_i through grassed swale treatment. lin Proceedings of the International Symposium of Urban . Hydrology, Hydraulics and Sediment Control, LeJ..ingl:on, I(]{~ pp. 173-182. Occoquan Watershed Monitoring Laboratory. 1983. Final Report: Metropolitan Washington Urban Runoff Project. Prepared for the Metropolitan Washington Council of Governments, Washington, DC, by the Occoquan Watershed Monitoring Laboratory, Manassas, VA Pitt, R., andJ. McLean. 1986. TorontoArea Watershed Management Strategy Study: Humber River Pilot Watershed Project. Ontario Ministry of Environment, Toronto, ON. Schueler, T. 1997. Comparative Pollutant Removal Capability of Urban BMPs: A reanalysis. Watershed Protection Techniques 2(2):379-383. Seattle Metro and Washington Department of Ecology. 1992. Biofiltration Swale Performance: Recommendations and Design Considerations. Publication No. 657. Water Pollution Control . Department, Seattie, W A. Southeastern Wisconsin Regional Planning Commission (SWRPC). 1991. Costs of Urban Nonpoint; Source Water Pollution Control Measures. Technical report no. 31. S01;ltheastern Wiscons~n Regional Planning Commission, Waukesha, WI. U.S. EPA, 1999, Stormwater Fact Sheet: Vegetated Swales, Report # 832-F-99-oo6 httD:l!www.epa.gov/owm/mtb/vegswrue.ndf, Office of Water, Washington DC . Wang, T., D. Spyridalds, R Mar, and R. Horner. 1981. Transport, Deposition and Control of Heavy Metals in Highway Runoff. FHWA-WA-RD-39-10. University of Washington, Department of Civil Engineering, Seattle, W A. Washington State Department of Transportation, 1995, Highway Runoff Manual, Washington State Department of Transportation, Olympia, Washington. Welborn, C., andJ. Veenhuis.1987. Effects of Runoff Controls on the Quantity and Quality of Urban Runoff in Two Locations in Austin, IX. USGS Water Resources Investigations Report No. 87-4004. u.S. Geological Survey, Reston, VA. Yousef, Y., M. Wanielista, H. Harper, D. Pearce, and R. Tolbert. 1985. Best Management Practices: Removal of Highway Contaminants By Roadside Swales. University of Central Florida and Florida Department of Transportation, Orlando, FL. Yu, S., S. Barnes, and V. Gerde. 1993. Testing of Best Management Practicesfor Controlling Highway Runoff. FHWA/VA-93-R16. Virginia Transportation Research Council, Charlottesville, VA. 111lfo1fmation Reso1l8.ll°cces Maryland Department of the Environment (MDE). 2000. Maryland Stormwater Design Manual. www.mde.state.md.usjenvironment/wma/stormwatermanual. Accessed May 22, 2001 . Reeves, E. 1994. Performance and Condition of Biofilters in the Pacific Northwest. Watershed Protection Techniques 1(3):117-119. January 2003 California Storm water BMP Handbook New Development and Redevelopment www.cabmphandbooks.com HH 11 of 13 1Fce=~@ ~~~~tt@f1:(§©~ ~\l1W@~~ ."'~"' . .,-., . " ........ _ '-_" .. " .. , ....... _' ...... r·."· ..... ·"--_C ... ,. """~'"·i,,d ..... ·~., .. _"_~.w~ .. "_." ... _" ", .0£, •• , _ ...... j Seattle Metro and Washington Department of Ecology. 1992. Biofiltraiion Swale Perfvrmanee. Recommendations and Design Considerations. Publication No. 657. Seattle'Metro and Washington Department of Ecology, Olympia, WA. USEPA 1993. Guidance Specifying 1Vlanagement Measures fvr Sources oj Nonpoint Pollution in Coastal Waters. EPA-840-B-92-002. U.S. Environmental Protection Agency, Office of Water. Washington, DC. Watershed Management Institute (WMI). 1997. Operation, Maintenance, and Management oj Storm water Management System·s. Prepared for U.S. Environmental Protection Agency, Office of Water. Washington, DC, by the Watershed Management Institute, Ingleside, MD . • • 12 of 13 California Stormwater BMP Handbook New Develo!Jment and Redevelopment www.cabmphandbooks.com January 2003 I' • • • ~®~®fb@l~~(QJ ~~@]m~ I "~ _ ". _____ ........ _~~" ~ _l""-......... ·~""I""..,-, __ ._">",,,-~_. __ .<:. ___ • __ ~_._ . ____ ("'..,."._~"' .• Notatlcm: / f'£'illiide tor SOOllr iil(;:it~e~(m. 1,.t-'-................ ~""'-..... Il..........,-~~ ....... q, f;§1f~ L ----------------1 i. = LCllgUI iI!f swaleo impllLUtdmG>nt lll"OO P& Gilock <i.."I!il iit) (I;) UifiWlt'lillllai WOO' ur $wai" itlBjlOulltfmellt 9rca. Os =Ilajltllofcl'lookdllm(f!) S;:; '" Bott;)llt s!pe of swa/t.) (ftff!) l?J '" t'CIH'Jldlll ofcttoolHI.'lJl'I {ii) We c BGttomW"KI!Il(lfdlOllkd~m(ft) Ztsa;: Rali<:l (if IIMZo!:lllfa! t" VElrt!c<!! ollany", lim sl.'J!l!.;) snfla S!Ollll (riff!) -V'" - January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 13 of 13 • MM~1tB~6® ~W$ft~m ~@~li: ~!h~et 1f«:=~@ "6R'~-!!:::c_H __ ,eg-~ ....... 4,> p:~."" L:;U:!1~h.; ,.,.~..." ~~""~' _ h'-'~'~''''''-$f?"&",'-'"''''.G¥_ ",,",-a;;app,e::-._""7_ #%#4"'-£A4?¥*~_""h""'''e5i'W-&5fe-f;:;;;;''':ez..:r: 0~ P_}t., 4 ... _.9._ I ,-_I D@l${:ti"HpttS@1fil A multiple treatment system uses two or more BMPs in series. Some examples of multiple systems include: settling basin combined with a sand filter; settling basin or biofilter combined with an infiltration basin or trench; extended detention zone on a wet pond. California Experience The research wetlands at Fremont, California are a combination of wet ponds, wetlands, and vegetated controls. Advantages • BMPs that are less sensitive to high pollutant loadings, especially solids, can be used to pretreat runoff for sand filters and infiltration devices where the potential for clogging exists. • BMPs which target different constituents can be combined to provide· treatment for all constituents of concern. • BMPs which use different removal processes (sedimentation, filtration, biological uptake) can be combined to improve the overall removal efficiency for a given constituent. • BMPs in series can provide redundancy and reduce the likelihood of total system failure. Limitations • Capital costs of multiple systems are higher than for single devices. • Space requirements are greater than that required for a single technology. Design and Sizing Guidelines Refer to individual treatment control BMP fact sheets. Performance • Be aware that placing multiple BMPs in series does not necessarily result in combined cumulative increased performance. This is because the first BMP may already achieve part of the gain normally achieved by the second BMP. On the other hand, picking the right combination can often help optimize performance of the second BMP since the De$ogn (;@lfilsederGllfi:s@lfils !:j Area Required ill Slope II Water Availability II Hydraulic Head • Environmental Side-effects Targeted Constituents .,/ Sediment - .,/ Nutrients • .,/ Trash -.,/ Metals -.,/ Bacteria • .,/ Oil and Grease • .,/ OrganiCS -'Legend (Removal Effectiveness) • Low -High • Medium influent to the second BMP is of more consistent water quality, and thus more consistent performance, thereby allowing t.h.e BMP to achieve its highest performance. iii When addressing multiple constituents through multiple BMPs, one BMP may optimize removal of a particular constituent, while another BMP optimizes removal of a different f # i? January 2003 California Stormwater BMP Handbook New Develol)ment and qprlPllpl""""'P"It 1 of 2 constituent or set of constituents. Therefore, selecting the right combination of BM-Ps can be very constructive in collectively removing multiple constituents. Sntnng Critewfta Refer to individual treatment control BMP fact sheets. Additional Design GuideDHnes Iii When using two or more BMPs in series, it may be possible to reduce the size of BMPs. !ill Existing pretreatment requirements may be able to be avoided when using some BMP combinations. Maintenance Refer to individual treatment control BMP fact sheets. Cost Refer to individual treatment control BMP fact sheets. Resources and Sources of Additional Information Refer to individual treatment control BMP fact sheets. 2 of 2 California Stormwater BMP Handbook New Development and Redevelopment January 2003 ( ( • • 1l)~$)©fFH!}ll1tO@1i'fI Drain inserts are manufactured filters or fabric placed in a drop inlet to remove sediment and debris. There are a multitude of inserts of various shapes and configurations, typically falling into one of three different groups: socks, boxes, and trays. The sock consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the grate of the inlet hqlds the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene "bag" is placed in the wire mesh box. The bag takes the form of the box. Most box products are one box; that is, the setting area and filtration through media occur in the same box. Some .products consist of one or more trays or mesh grates. The trays may hold different types of media. Filtration media vary by manufactUrer. Types include polypropylene, porous polymer, treated cellulose, and activated carbon. California Experience The number of installations is unknown but likely exceeds a thousand. Some users have reported that these systems require considerable maintenance to prevent plugging and bypass. Advantages II' Does not require additional space as inserts as the drain inlets are already a component of the standard drainage systems. II Easy access for inspection 'and maintenance. II As there is no standing water, there is little concern for mosquito breeding. II A relatively inexpensive retrofit option. Limitations Performance is likely significantly less than treatment systems that are located at the end of the drainage system such as ponds and vaults. Usually not suitable for large areas or areas with trash or leaves than can plug the insert. Design and Sizing Guidelines Refer to manufacturer's guidelines. Drain inserts come any many configurations but can be placed into three general groups: socks, boxes, and trays. The sock consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the grate of the inlet holds the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene ''bag'' is placed in the wire mesh box. The bag takes the form of the box. Most box products are January 2003 California Stormwater BMP Handbook New Development and Redevelopment [i)®~H~1i'il (6@1i'il~8@1~m~ril:n@flilg) pj Use with other BMps fI Fit and Seal Capacity within Inlet Targeted Constituents ./ Sediment ./ Nutrients ./ Trash ./ Metals Bacteria ..t Oil and Grease ./ Organics Removal Effectiveness See New Development and Redevelopment Handbook·Section 5. =-' ..... '--..... ..=..-=,===,-===== Stormwater Quality ASsociation 1 of: 3 II!:!> = ~ 9\ """ '" "" ~ "'l li!' ~ '"'''''' r· tf;'"" ~ ~ .. F r;EJ ~ . ~ GJ Wj W W ~ J1 ~ B etJ~ I l1x~ ;c-? , •• -.-,,-~-%-·rB ",?,_o~ f W"-' -A··M .. -•. ·._.R., •.... -!i£."-" ~ ... "~--. --"--'~'4"--+-b-?'?-••. -""-w""P -H,.s .= .. " .. &;1_ .. ..,. ... _.~"x··;.' ... n%'_ .... ,.=. i one box; that is, the setting area and filtration through media occurs in the same box. One manufacturer has a double-box. Stormwater enters the first box where setting occurs. The stormwater flows into the second box where the filter media is located. Some products consist of one or more trays or mesh grates. The trays can hold different types of media. Filtration media vary with the manufacturer: types include polypropylene, porous polymer, treated cellulose, and activated carbon. Construction/Inspection Considerations Be certain that installation is done in a manner that makes certain that the stormwater enters the unit and does not leak around the perimeter. Leakage between the frame of the insert and the frame of the drain inlet can easily occur with vertical (drop) inlets. Performance Few products have performance data collected under field conditions. Siting Criteria It is recommended that inserts be used only for retrofit situations or as pretreatment where other treatment BMPs presented in this section area used. Additional Design Guidelines lOW guidelines provided by individual manufacturers. ( ntenance Likely require frequent maintenance, on the order of several times per year. Cost • The initial cost of individual inserts ranges from less than $100 to about $2,000. The cost of using multiple units in curb inlet drains varies with the size of the inlet. foil The low cost of inserts may tend to favor the use of these systems over other, more ~ffective treatment BMPs. However, the low cost of each unit may be offset by the number of units that are required, more frequent maintenance, and the shorter structural life (and therefore replacement). References and Sources of Additional Information Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert, Planet CPR, Seattle, Washington Interagency Catch Basin Insert Committee, Evaluation of Commercially-Available Catch Basin Inserts for the Treatment of Stormwater Runoff from Developed Sites, 1995 Larry Walker Associates, June 1998, NDMP Inlet/In-Line Control Measure Study Report Manufacturers literature • a Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project - uation of Potential Catch basin Retrofits, Woodward Clyde, September 24, 1998 . 2 of 3 California Storm water BMP Handbook New Develo'lment and Redevelollment January 2003 • • Woodward Clyde, June 11, 1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint SOUJrce Pollution Control Program . January 2003 California Stormwater BMP Handbook "I""., '"''''H'''I,,''' ..... ''' ... I-",nrf ~prfpHP''''''rnpnt 3 of 3 I (L / .NVMRONMENTAl SERVMCESg MNC0 l. ( V The Call~orn~a Curb She~f Basket Water FIgur81 FIgureS CltdlBa8ln Wall DGI8IJa of Z-mold Flglh82 I San Diego regional &laIIdard CUItt 1nIat-1'p B I 'I-t. • 'f ' .. . • l ' .. Manhole , .. .~'. I~;al II J . :j'" ... 0' . .so... '., • . Q .. " e "Ill" .... , -, -•• ~ ',-7-'. ' P.O. Box 869 Oceanside, CA 9204.9 (760) 433·7640 • Fax (760) .433.3176 www.biodcullcmvinmIJltmtul.m:t , . . •• 4'. . , " .... ,. ( I ~NVIR E YLlL SE VICES, ~NC&1 Grate Inlet Skimmer Box Curb Inlet Basket Nutrient Separating Baffle Box . REPORTS a. DATA Pollutant Loading Analysis for Stormwater Retrofitting in Melbourne Beach, Florida PoButaDt Removal Testing for A Suntree Technologies Grate C. Inlet Skimmer Box I.. Site Evaluation of Suntree Technologies, IDe. Grate Inlet Skimmer Boxes for Debris, Sediment And on & Grease . Removal . >'.''':.<, .... ~:.: ... :::./:--. J. , .. " ~' ......... ~~ •. . . . . . . ". . .. ~ '. ." -.-"" .. -.~ __ :: __ ~_~~~'-___ .J ~~o (:lJ!A~'" ENVIRONMENTAL SERVICES, INCa POBOX 869, OCEANSIDE, CA 92049 (160) 433-7640 FAX (760) 433-3178 •• ( '. IP\\l)nnlUlii~lliIf!: JL@m«Rlllffi~ AB!l~n1~nEl JF®Jl" §~@ll"ll1ffi'W~t®li~ ~®frll'®fn~nlID.~ tim M~nlbJ@mI!l"lJlle B®mcl'm? Introduction Ffilllllrfic1l~ By~ GordoD England9 P.Eo . Creecb Engineers, Inc. 4450 W. Eau Gallie Blvd, #232 Melbourne, Fl. 32932 At Gemini Elementary School in Melbourne Beach, Florida, there has been a history of repeated flooding on the school grounds and in properties adjacent to the school. In 1999 Creech Engineers, Inc. (CEI) was chosen by Brevard County Storm water Utility to design drainage improvements to alleviate these flooding conditions, as well as to provide for stormwater treatment within this 20.06 hectare drainage basin. The project was divided into two phases. Phase 1 improvements were made in order to accelerate initial flood control measures for homes downstream of the schooL Phase 2 involved the design of more extensive flood and water quality control measures along Oak Street for further protection of school property and roadway flooding at nearby ch~ch property. This paper highlights the political challenges of retrofitting storm water systems in developed areas, as well, as demonstrates a methodology for performing a nanpoint source pollutant loading analysis. Existing Conditions Gemini Elementary School is located on a 8.02 hectare, triangular shaped property along the south side of Oak Street, a two lane collector road in Melbourne Beach, about one half mile from the Atlantic Ocean. See Exhibit 1. Residential properties lie downstream of the school, along its southeast and southwest borders. 8.51 hectare Doug Flutie Park is on the north side of Oak Street. A so~r club uses the park and school grotmds on it daily basis. There was no stormwater system at the par~ along Oak. Street, or on the school site. Storm water flowed southward off Doug Flutie Park, across Oak Street, through the school site, and into the yards and homes south of the school These yard$, and the rQads downstream oftbem, are very flat and. only a few feet above sea level. Once water stages high enough in the yards, it graduaUy sheettlows down the adjacent roads a few hundred yards to the Indian Rivero' The affected homeowners naturally blamed the schQol for anowing the scbool~s water to flood them. West of the school, a few hundred yards along Oak Street, was a low point, in the roa4 where water ponded and flooded the road and an adjacent churchyard. Due to a thin clay lens at 26 cm deep causing a perched water table, water stood in the road for several days after even a nominal rainfall. This drainage basin was almost completely bUilt out, with no easy path for developing outfalls to relieve flooding. ,.e (e 'fhls section Olf the IlmdiOO1l River is a Cl~s 2 w~t@Il" body, wi&. a Shellfish Harvesting classification bringing intense scrutiny IDro)Hll the St Joms River Water Management District. Corp of Engineers permittmg i$ 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 road, 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 Bridge Department, Brevard County Stonnwater Utility, a church, three different Homeowners 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. Proposed 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 COWlty personnel along the south property lines 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 18U outfitll pipe were cOnstructed in a utility easement through two heavily laDdscaped and fenced yards, to Pompano Street, where it was tied into an existing storm drain pipe. A shorf 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. Fortunately, Gemini Elementary School had a significant area of vacant land on their site. The school entered into agreements with Brevard CoWlty allowing the construction of three dry retention ponds totaling 2.95 hectare to reduce flows leaving the school site, as well as provide stormwater treatment where none existed. These dry ponds were wound around several soccer and baseball fields. The soccer field's locations had to remain 'in place due to previous agreements with the school and Parks and Recreation Dept. The ponds were only 26-40 em (12"-18',) deep and sodd~ allowing the soccer teams to use the pond areas as practice fields when dry. When the ponds were excavated, the confining clay layer was removed to allow for infiltration though the beach sand at the site. Construction was scheduled during the summer when school was out. . . A control structure was designed at the outfall pipe location to provide protection for a 2S - year storm. The temporary connection to the existing downstream pipe had overloaded the downstream system in a heavy rain event, so a new outihll to the IndiaD River was designed through a park adjacent to the River. The-park was owned by a Homeowners 2 (e Asso©i~tioIffi9 which li'~l1lll©taIffit[y g~v~ a dbr@1i1oog~ e~emellllt through theparJk:. The County agreed to make several impmvemems to the park ariid its boat A'amp in exchange for the easement. The Corp lOf lElfigmeers was c{lIooemed that the new outfaJl pipe discharges would impact the nearby seagrasses, so the new discharge pipe was not pennitted to be constructed in the Indian River. A bubbleu)) box was designed ten feet back from the shoreline and rock riprap was placed between the bubbleup box and the mean high water line to prevent erosion. As mitigation for disturbing the shoreline, spartina and other plants were planted among the rocks to further buffer the shoreline from the storm water discharges. This first phase of improvements was :finished in September 2000 at a cost ofS124,OOO. The improvements implemented proved successful in preventing any flooding of adjacent homes in several large rainfalls in 2001. The second phase of the project addressed stonnwater quantity and quality concerns along 1650 meters of Oak Street, :from AlA to Cherry Street. To provide further flood protection at Gemini Elementary School, retention swales were designed along both sides of Oak. Street and 625 meters of storm drain pipe was designed to ,intercept runoff and prevent it :from crossing the road onto school property. The piping also provided an outfan for the low spot in the road by the church. This new pipe syste~ discharged into a residential canal system, which was used by many of the adjacent residents for boating to the Indian River Lagoon (Bay). These canals were very politically sensitive· since they were in peed of dredging and the Town ofMelboume Beach does not dredge caUals. The residents were concerned that the new storm water system would lead to further sedimentation of the canals. The. fb;st alternativ~ for .treatment was to use land at the church site for a pond ~or the road ~otf. The church was willing to donate the 1and where their septic tank fields were located if the County would provide a sewer connection. This scenario was designed, but when it came time for the church to give easements to the County" they balked and it was back to the drawing board.' , St. Johns River Water Management District, (District), criteria requires stonnwater treatment for improvements which a) increase discharge rates b) which increase ponutant loadings, or c) which increase impervious areas. With this project, no new incn;ased impervious areas were propo~ but there would be additional water flowing to the residential canal ft9m the extension of the pipe system to the flood prone areas. These new flows create the potential for increased pollutant loadings to the canal. Normal design methods would have used treatment ponds to offset these potential impacts. Due to lack of available land for ponds, a1temative treatment methods were proposed for this project. The District will consider alternative treatment methods if it can be demonstrated that all other possible alternatives have been exhausted. It would not be possible politically to use more school or park area for treatment ponds. For this project, eEl showed that the only alternatives were to tear down houses for ponds, or use alternate treatment technologies. 3 ( • The treatment stlrategy wv(()hroo maxlimmg tlreatffient methods within the project basin with alternative BMPs? as well as retrofitting two adjacent watersheds as additional mitigation. A total of 1061 a©ft'© fre~ 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 Tecbnologies$ 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 Bafile Boxes are in-line storm water 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 had 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 concem in the canals since the nutrients promote algae blooms, which in turn increase muck build up in the canals. In offsite drainage Basin 5, there are 3 existing pipes which discharge directly to the canals. Three baffle boxes and 6 curb inlet skimmer boxes were designed to provide sediment and nutrient treatment for this drainage basin. Brevard County Storm water Utility will implement this project and be responsible for all maintenance oftbe improvements. The baffle boxes will be inspected twice a year and cleaned as needed. The wet traps will be cleaned twice a year.. Brevard County has a vacuum. truck de.dicated to cleaning stormwater Blv.IPs •. Using numerous B:MPs used on this project provided a high degree of treatment for the new piping system along Oak: Street, and pr~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 ExluDit 1 for a map of the improvements. Calculations In Phase 1 of the project, the dry ponds and outfiill pipes were modeled hydraulically using the Interconnected Pond Routing program.' Since the dry ponds in the Phase 2 project area were too small to provide effective attenuation, the predevelopment and post development runoff calculations were made using Hydratlow and the rational method. The only available storm drain pipe for Phase 2 was a 36" pipe in offsite Basin 4. The new 'piping along Oak Street was connected to the existing 36" pipe, and the piping downstream of the connection was upgraded to a 42" pipe. The pipes were designed for a 25 year storm. Basins 1,2, and 3 were a much longer distance from the outfall than Basin 4. As a result of different times of concentration, the peak flows from Basin 4 passed sooner than Basins 1,2, and 3, giving only a slight increase in peak discharge; despite adding 12.25 hectares to the area flowing to the existing outfall. . The potential for increased pollutant loadings in the canal system was a concern of local residents. These canals had a history of dredging operations every 8-10 years, an~ the 4 • • r~sRdell1lts did mot woot t@ m©1reas~ the :Iffr©q1J.ll€;)1lll©Y of ©ost].y cllr~dgmg. The X'i!12tm ponu~lmts of lConcern leooing to muc~{ deposition m the ©~ls weIre ToWl Suspended Solids (TSS)? Total! Nitrogen (TN)~ and To~~li lFhosplOOms (TP). Sedimem build up at the end of the pipes was common" Nutrient loadings :from grass ©lippings~ leaves~ and fertilizers leads to algae blooms and low dissolved oxygen in the canals, which in tum leads to muck build up from the eutropmlCatiofll pmcess. Most of the material dredged from residential canals is typically muck. To address this concern, a pollutant loading analysis of the existing and proposed storm water discharges was performed. In the existing conditions, the only stormwater treatment for the canal system was a baftle box along Cherry Street for.ofi'site Basin 4 of 24.24 hectares. There were a total of1 outfall pipes discharging into the canal system. , In the first phase of this pr()ject 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 than the canal system, so these pollutant loads were not included in the pollutant load analysis for the canal outfall. The existing pollutant load to the canal only came from the drainage Basins 4 and 5, totaling 31.2 hectares. The runoff ftom Oak. Street did not drain to the canal in existing conditions, only in the post development conditions. The strategy for the ponutant analysis Was to calculate the pollutant loads in the existing conditions, and then calculate the pollutant loads after the new pipes were added to the system and offsite areas retrofitted for stormwater'treatment. The pollutants used in this analysis were TSS~ TP, and TN. Each drainage basin was categorized by land use. Areal, annual, mass loading rates from "Stormwater Loading Rate Parameters for Central and South Florida", Harper, 1994, were multiplied by each basin's area to give existing and potential annual pollutant loadings. See Table 1. . The next step was to calculate the pollutant removal rates for the different BMPs. Individual BMP removal efficiencies were take from "A Guide for BMP Selection in Urban Developed Areasu , EWRI, 2000. What was challenging with this analysis was the use of multiple BMPs in series for the treatment train. Each BMP receives cleaner and cleaner water as the water moves down the train. At each BMP, the removal efficiency for each constituent was multiplied by the remaining percentage of the initial loading to give a weighted, cumulative~ removal e:fficiency for each constituent. See Table 2. These calculated removal efficiencies were then multiplied by the total calculated pollutant loads to give the reduced pollutant loadings after the BMPs were installed. See Table 3. Table 4 shows that the total loads to the canal were reduced as a result of the retrofitting of onsite and offsite basins . The pollutant loading analysis below demonstrates that as a result of the numerous BMPs proposed, the total pollutant loadings entering the canals after project completion will 5 ( • . acb.mIlly be sigmficamKy li'©Qlu©~d\ from the IS}Jristmg ponill.l1tm'l1t li(())~dimgs @ntermg the ©anabl. The key to overaU [P((»UutMt lLtxlhllctnoIffi is t@ provide ~ditionru treatment in offsite dramage basins. This win ll'©sUl!lt m 1m 0011: 0000& @freducOO1 p@llutmts entering the c~ai$ and a reduction of the severe flooding often seen along Oak Street. Table 1 Existing Pollutant Loading Loading Rate* Potential Pollutant Loading Land Use * From "Stormwater Loading Rate Parameters for Central and South Florida", 1994. Harper ** Basin 4 has an eXisting baffle box providing treatment. Basins 4 and 5 are the existing pollutant loadings to the canals . • 6 • • 1r~\hlKe Al lIlMIJPll@HHl1lltalill~ R®IDID®W~B$ BMf! fOILILIlJii'ANT ReMOVAL TABlE* I3MP BMP Removal Efficiency Type -,%) , TSS TP TN DrvPond 85 61 91 Swale 80 45 25 Baffle Box 80 30 0 nlet Trap (grated) 73*" 79fdr 79*" Inlet TraD (curb) 2*"* 11*** 10- Iswale + Inlet Trap (g) + Baffle Box 98.9 91.9 84.2 Iorv Pond + Inlet Trap-(a)+ Baffle Box 99.2 94.3 98.1 nlet TraD (c)+ Bame Box 84 37.7 10 Inlet TraD (0)+ Baffle Box 81.1 85.3 79 Multiple BMP Pollutant Removal Calculations ~wale + Inlet Trap (9) + Baffle Box , TSS -100x0.8 + (100.80»(0.73 + (100-80-14.6)xO.8 = 98.9% Removal TP -100xO.45 + (10045)x.79 + (1~.45) = 91.9% Removal TN -100x.25 + (100-25)x.79 = 84.2% Removal .,ry Pond + Inlet Trap (g) + Baffle Box TSS-100xO.85+ (1Q0..85)xO.73 + (100-85-10.95)xO.8 = 99.2% Removal TP -100xO.61 + (1Q0.61 )xO.79 + (100-61-30.8)x.3 = 94.3% Removal TN -100x.91 + (100-91)x.79 = 98.1% Removal .nlet Trap (c) + Bame Box TSS -100-x0.2 + (100-20)xO.8 = 84% Removal TP-100xO.11 + (100-11)x.3= 37.7% Removal TN -100x.10= 10% Removal Rlet Trap (9' + Baffle Box TSS -100x0.73 + (1QO..73)xO.30 = 81.1% Removal TP -100xO.79 + (1QO-79)xO.3 == 85.3% Removal TN -100x. 79 = 79% Removal All removal values are from "Guide For Best Management Practice .:,.:. From Creech Engineers study "Pollutant Removal Testing For a Suntree Technologies Grate Inlet Skimmer Box", 2001 ***From visual observation by Brevard County staff Table 3 Proposed PoUutant Loading 7 • • ~MIfllIft@fMl@i'\f~O ~mcaellii~ 1fll@!~~g'8a I!,.ooi!l.l ~aSBIlil ~WJ!,9l wif@m lNl~t'l? ~rtl11P$ ~@lIlllq;ti®IDl 1P>li'@~oooo'l ffilIl)IH.Im~ 'ii'JI!lJ@ «%) from ~M'$ (kglyeall', /L@a~lllg'(kgiyeaii') iSS TP TN TSS TP TN 1'SS TP TN 2A sweile + inlet bW (~) o{)o l:iaffleblm 98.9 91.9 84.2 69.38 0.39 8.32 0.77 0.03 1.56 28 swale+ inlet trap fol + baHle box 98.9 91.9 84.2 8.64 0.05 1.04-0.10 0.00 0.19 2C dry pond + inlet trap tg>'" baffle box 99.2 94.3 98.1 5.81 0.03 0.81 0.05 0.00 0.02 2D drv Dond + infetfraD (a) + baffle box 99.2 94.3 98.1 10.93 0.06 1.52 0.09 0.00 0.03 2E dry pond + inlet trap Cal + baffle box 99.2 94.3 9&1 19.83 0.11 2.76 0.16 0.01 0.05 2F swa1e + inlet traD Cal + baffJe box 98.9 91.9 84.2 14.81 0.08 1.77 0.16 . 0.01 0.33 2G . dry pond + intet trap (g) + baffle box 99.2 .94.3 98.1 5.65 0.03 0.79 0.05 0.00 0.02 2H .dtY pond ... inlet trap (g) ... baffte box 99.2 94.3 98.1 9.73 0.06 1.35 0.08 0.00 0.03 2t swale + inlet trap (g) + baffie box 98.9 91.9 84.2 0.60 0.00 0.07 0.01 0.00 0.01 2J inlet frap(g) + baffle bOx . 81.t 85.3 79 4.93 0.03 0.68 1.15 0.01 0.18 2K inlet trat) Cal + baffle box 81.1 85.3 79 3.51 0.02 . 0.48 0.82 0.00 O~13 2L infet fran ta) + baffle box 81.1 85.3 79 2.10 0.01 0.29 0.49 0.00 . 0.08 3A inlet IJw) to) + baffle box 81.1 85.3 79 99.64 1.11 8.10 23.22 0.19 2.15 as inlet traP (a) + baftle box 81.1 85.3 79 137.40 1.SS 11.11 32.02 0.26 2.97 3C dry fJond +'ln1et traP Cg} + baftle box 99.2 94.3 98.1 1367.83 2.46 20.43 11.03 0.15 ·0.40 4 inlet traD (q) +. bafHe box 81.1 85.3 79 544.99 21.25 221.46 127.01 3.66 58.87 5A inlet traD (c) + baffle box 84 37 10 278.03 1.30 2.76 52.96 2.21 24.85 58 inlet trap ecl +. baffle box 84 "S1 10 406.21 1.89 4.03 Tl.37 3.23 36.31 • , 5C inlet trap ee) + baffle box 84 37 10 126.29 0.59 1.25 . 24.06 1.00 11.29 Tolal 2305.77 27.24 281.03 197.19 4.34 67.01 Table 4 Net Pollutant Removals TSS (Aw')t; TP(kg[yr) TN(IqVyr) Predevelopment 3015.18 35.13 380.83 Postdevelopment 630.97 21.95 289.15 Net Reduction 2384.81 (790.4) 13.18 (37.52%) 91.68 (24jl1%) Summary The days of solving flooding problems in communities with simple dit~h and pipe solutions have disappeared. Environmental concerns now dictate that· stormwater treatment techniques be integrated into these flood relief projects. By adding water 8 • .' • qlllality ~omponeilts ~o water Q.1Lmntity JPlrojetCt$~ ~omm:e.mitlie$ ~an help achieve pollution remediation goals being established foll' NPDE§9 rMDL~ and PLRG programs. ' Retrofitting existing st~rmwater systems to provide water quality treatment is more complicated, expensive, mld 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 B:MPs in these locations. An carefully planned treatment train was designed consisting of swales, ponds, berms, baffle boxes, and inlet traps tQ provide overall stormwater pollution reduction. In order to address storm water 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 stormwater 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 J,let reduction of 79% for TSS, 37% fat: 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 the process throughout the life of the project. Many meetings were held with city, county, and state officials, homeowners asso~iations, 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 acquisjtion process after ltlany verbal indications ot approval. Using creative partnerships with other entities and agencies allowe4 the development of a unique strategy to solve flooding at several locations in the project area. Referenees AseE -"Guide For Best Management Practice Selection in Urban Developed Areas", 2001 Gordon England, P.E. "Pollutant Removal Testing For a Suntree Technologies Orate Inlet Skimmer Box", 2001 Harvey Harper, Ph. D, P .E., "Stormwater Loading Rate Parameters for Central and South Florida", 1994 9 \ \ / \ (. POLJLUT, .. ' REMOV AJL TESTIN FOR. A §UNT E TECHNOLOGIES GRATE INLET SKIMMER BOX Prepared for Suntree Technologies, Inc. November 2001 . eEl Project #21121.00 Prepared By: . ' . .,:': ':' . :: ,:.::' ',' :~,: ·:·:;':':;;·~~,1: . :' ':..~ . '.:: .;: .. ':" '>,,!' :', ~ ~~:~ ~~,~~\~:~·.f~:,,<""·:t;~·~;:~; .. :~~:.: / ... :-:4..::~'~'-;-;,::;,;:,,;~~ .. ';:' ~:: .::' ;';: .:.i.:/~ :.,,:,.} ·'·"C:~t·~CfrH ~~G~N~~~~~q ~w~cu c~\~nU .. llilA'b"B()~\Ii : '. ,. f:!NGDINHarar(,rap 4450 W. Eau GalDie Blvd., Ste. 232 Melbourne, FL 32934 (321) 255-5434 ,. ( • Background Methodology Results Table 1 -Sediment Sieve Analysis Conclusions APPENDIX A )0 Site Photos APPENDIXB PAGE 1 2 2 3 3 )0 Universal Engineering Sciences Grate Inlet Skimmer Box Evaluation Report • • p@na!!ll~lIDt R®!lMl®w~B 1re~tiIDlg for ~ SiJ!l@tr@@ T~~hnol«»gi~~ Grat~ iimi~t Skimmer Box by , Cr€ledl Englneen, In~. November 2001 With special thanks t@ Joftnie Regan of the Cocoa Beach Stormwater Utility Background: Over'the last several years~ a number of BMPs have been developed to provide stormwater treatment by trapping poButants and debris in inlets. Inlet trap BMPs are quasi source controls, being inexpensive, requiring no roadway construction or utility relocation, and beping pollutants out of the water bo~ rather than trying to remove the polh$nts ftom the Water once it is contaminated. Suntree TecJmologies, of ,Cape Canaveral, Florida commissioned Creech Bngineers, Inc. aDd Universal Engineering t9 perlbrm. testing on a Grate Inlet Skimmer Box (GISB) to detennine its po~ removal effectiveness for sediment and grass clippings. The testing was per1brmed on September 26, 2001. Attached are photographs fiom the test and the accompanying report by Universal Engineering S~es. The GISB is designed to trap sediment, grass, leaves, orgauic debris, ftoatillg trash, and . hydrocar11ons as they enter a grated inlet, thereby preventing these pollutants, fiom entering the stormdtain system. where they would cause detrimental impacts on doWDStteam waterbodies. 'I'he GISB is a 3/16" thick 1ibetgJai;s device custom made to fit most types" of grated inlets. The overftow capacity oftbe GISB is' designed. to be gteater than the cUrb grate capacity, thereby insuring that there wD1 be no loss of hydraulic capacity due to the device being ~ the inlet The bottom oftheGlSB is designed to be above any pipes entering or leaving the inlet so that flow through the iolet is not blocked. Water flowing through the grate first encounters a hydrocarbon absorbing eeBulose. This boom also serves to trap large debris between the boom and the body of the GI~B. At the bottom of the trap are a series of stainless steel filter screens coveriDg 3.S inch wid" cutouts in the fiberglass body. These screens trap debris wbD.e allowing water to pass through the bottom of the body and out to the storm drain system. ~ screens in the floor and :first vertical row of the OISB are fine mesh. The second vertical row of screens are medium mesh and the highest roW are coarse mesh. On the outside ,of the cutouts the SCreens are backed by stainless diamond plate to provide support to the scteeDS since heavy loads of debris build up in ~ box. If the flow rate through the inlet ,exceeds the," capacity of the filter screens there is another row of overflow holes cut out with no screens. These overflow holes allow water to pass through the GISB even if it becomes full of debris. The level of the holes is above the bottom of the top tray, enabling the tray to act as a skimmer to prevent floating trash &om escaping through the overflow holes. 1 • Abcpu~ oollfWay @@WiTIt ~lht(g roo~ H$ ~ di1ffins~li' ,l!at~ ~@ ~~ li'€J3UllSjpJ@mi@lffi «»f U'.allPp©d1 sediment K~t traps SUtch Iil$ these are genemlliy designed to capture hydrocarbons, sediment, and floating debris. rher~ is genercilly a wge build up of grass, leaves, and yard debris in the GISBs; which represent a source of nutrients, which do not enter the waterbodies. Royal and Englan~ 1999, determined that leaves and grass leach most of their nutrients into the water within 24=12 hours after being submerged in water. OISBs are designed to keep captured debris hi a dty state, off the bottom of the inlet, thus preventing phosphates and nitrates from leaching into the stormdrain system, where much more expensive B:M.Ps would be required to remove the dissolved nutrients. Methodology: A test was designed to simuJate a rain&ll event and measure the ability of a GISB to remove sediment and grass leaves from a typical grated inlet at 600 South Brevard Ave., Cocoa Beach, Florida. Joanie Regan of the Cocoa Beach Stormwater UtiUty provided this location for the test, as wen as a water truck to flush the curbs. Universal Engineering Sciences performed the testing, measurements, and sediment sampJing. Creech Engineering, Inc. observed the testing. The City has installed a number of these devices and Joanie indicated this location was typical of a normal installation. The grate, curb, and gutter around and upstream of the inlet were brushed and washed clean. A new, clean GISB was pJaeed inside the inlet. A water truck with a pump discharged reuse water into the gutter upstream of the inlet at a rate of SOO gpm (1.1 em). Dry, green St. Augustine grass clippings from a yard that had been recently fertilized were slowly ted into the gutter and flushed into the inlet. It was observed that the cast iron grate trapped a signifiCant amount of grass around the edges of the ·grate •. The grate was removed fur aU tests to enable aU oltho grass and sediment to . enter the box. After all of a measured sample of grass had been washed into the inlet, the grass was removed from the inlet, dried, and Weighed. Samples of grass before and after the test were sent to PC&B Laboratories in Oviedo, Florida. Laboratory a:naJ.ysis was performed to determine the Total Phosphorus and TKN content of the grass. Next, a sediment sample was washed through the GISB using the same methodology. Universal Engineering ran a sieve size a:naJ.ysis, using ASTM D 422 proced~ before and after the test. T.be sediment was cJassified as a poorly graded graveJy sand. The sediment was removed ftom the GISB, ~ and weighed. Results: Owing both of the tests, all water leaving the GISB passed through the filter screens. The water levels in the box only rose a few inches, with no water passing. through the overflow holes or coarse scr~ even though the bottom screens we~ completely covered with grass or sediment. There was a sman amount of grass and sediment that' passed between the box and the concrete waDs of the inlet because of the uneven edges of 2 • the wet. . 'fWs $Rt'i,)j~~Wlffi E~ fukRy ~\\llllll'il!Ofil@liil m m@$~ ooets dille w HIQ)«J)se t@i@X'M©e$ m ctOmtmctilQ))fi tec!miques, In the grass test9 6.58 nbs. @f grass were washoo into the irdet Mel 5.22 Ibs. were· captured, resulting in 1.36 Ib8. of grass passing through the GISB. This represents a removal efficiency of79.3%. The pretest grass sample had a Total Phosphorus content of 950 mglkg and a TKN content of 510 mglkg. The grass sample removed from the· GISB had a Total Phosphorus content of2,270 mglkg and TKN content of 90S mglkg. The sediment test was a little more complex. The initial results showed that of the 57.87 lbs. of sediment introduced to the GISB, 42.41 Ibs. were captured, giving a total mass removal efficiency of 73.3%. Universal Engineering indicates that the Pretest sample bad to.7 % grave), 88.0% sand, and 1.4% clay. The Post test sample bad 25.90A. gravel; 14.7% sand, and 1.7% clay. Gravel is considered to be particles No.4 ~ larger. Silt and clay is defined as particles passing the No. 200 sieve. Sieve Size 318" PreTest 94.3 %P~ Post Test 88.8 % Passing Difterence 5.5 Conclusions: Table 1 Sediment Sieve Analysis No.4 No. to No. 40 No. 60 89.3 81.8. 64.8 50.3 74.1 62.6 44.2 31.8 15.2 19.2 20.6 18.S No. 100 No. 200 25.5 1.4 ·14.7 1.7 10.8 .. 0.3 At the ftow rate tested, the GISB removed 79.3% of the grass clippings washed. into it. The ability of the OISB to remove grass during large flows when water passes through the bypass holes was not tested. In Florida, 90% of the storms are low rain&D. events of 1" or less, resulting in low flows similar to the test conditions. This makes the GISB a very effective BMP for Low flow events. It is unknown how e:tfectively the GISB works in large storm events. By keeping grass and other trapped organic debris in a dry state, the nutrieJ:lts in the debris do not leach out and become dissolved nitrates and phosphates. The GISB is a very effective BMP for preventing nutrients :from organic debris -from entering waterbodies. The significant increase in nutrient concentration after the test is probably attributed to the use of wastewater reuse·water during the test. the grass matted several inches thick in the bottom of the box. This thick layer could have acted as a filter to remove nutrients from the water source. At the flow rate of 1.1 em, the GISB bad a sediment removal etliciency of 73.3%. AS would be expected, most of the trapped sediment was gravel and sand, with Jittle fine material collected. The GISB has sediment removal capabilities rivaJiDg those tbund in many structural BMPs, at a fraction of the cost, and without disruptive construction. 3 ( UNI L '~!NjGMNEE!fU!NlG ~Cn~!Nl©~~ ......... ~Ift:~emmcal~~~o.~~~i'lres· ~iMMaierl&s 1i'~o Th.~ .cRilm 820 Brevard Avenue 0 Rockledge, Florida ~2955 (321) 638·0808 Fax (321) 63EH'978 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 Corner of South Brevard Avenue and South 8th 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 Proposal No. P01-0781. The evaluation was condu,cted 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 GI~B evaluation. 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 performed. prior to GIBB performance testing. The percentages of soil grains, by weig~t, retained 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 sample of known weight (57.87Ibs.) was placed on the pavement upstream of Ute GISB and washed into the GISS with a portable water source simulating a storm event. The captured sediment was then removed from the GISB, dried and weighed. The Captured sediment weighed 42.41Ibs. resulting in a loss of 15.46lbs. from the GISe testing. A gradation analYSis of the captured sediment sample (8-2) was performed. Universal completed particle size analyses on the two representative sediment samples (5-1 and B-2). The samples were tested according to the procedures for mechanical sieving of ASTM 0 422 (Standard Method for Particle Size Analysis of Soil$). In part. ASTM 0 422 requires passing each specimen over a standard set of nested sieves (% incb" No.4. No. 10. No. 40. No. 60. No. 100. No. 200). The percentage of the SOil grains retained on each sieve size are determined to provide the grain size distribution of the sample. The distribution determines • the textural nature of the soil sample and aids in evaluating its engineering characteristics. • Mr. Gordofl England November 2. 2001 Page :2 Pmject N@. 33186Q()Q2~t}1 Report Ndd!. 514r~ Sc~ consisted of 10.1 perc®JrO! @IroM~~ (@8"ain SOle j~lIgeB' ~han 4.15 mm)D 88.0 p@lfCent sand {grC'.l8rril size b~tweefil 41015 mm ~nd ~.15 mm)a f§lnd ~.4 p~foont fine$ (grain size les$ than ~)'015 rom). Sc2 consisted IOf 25.9 percent gjmve~. 12.4 petroont sand, and 1.1 percent fines. The grain size distribution curves era pre$ent~d as Attachment 4. According to the Unified Soil Classification System (USeS), s~ 1 and! 8=2 were classified as poorly-graded gravely sand [SP]. Based on the- gradation analysis, the major portion of the lost sediment was the fine sand component. Grass Clippings Test The grass clippings were supplied by Suntree Technologies. A grab sample of grass (0-1) was collected and submitted for laboratory analysis to determine the TKN (EPA Method 351.2) and Total Phosphorus (EPA Method 365.3) content A grass sample of known weight (6.58 Ibs.) was placed on the pavement upstream of the GISB. The grass clippings were washed into the GISB in the same manner as the sediment sample. The captured grass clippings were then removed from. the GISB. dried and we,ghed. The captured grass clippings weighed 5.22 Ibs. resulting in a loss of 1.36 Ibs. A second grab sample (G-2) was collected from the capturecf grass clippings and submitted for laboratory analysis to determine the removal efficiency for TKN and Total Phosphorus. The sampJes were shipped to PC&B Laboratories. Inc. in Oviedo, Florida. Laboratory analysis documentE>d 950 milligrams per Kilogram (mglKg) of TQtal Phosphorus and 510 mgIKg of TKN for G-1. Laboratory analysis documented 2.270 mg/Kg of Total Phosphorus and 905 mg/Kg of TKN for G-2. Laboratory Analytical Results and Chain-of-Custody Documentation are presented as Attachment 5. Universal appreciates the opportunity to provide environmental services as part of your project team. Should you have any questions, please do not hesitate to contact the undersigned at (321 ) 638-0808. . ~espectfully submitted. Universal Engineering Sciences, Inc. ~s.~ James E. Adams Staff Scientist II (2) Addressee Attachments Attachment 1: Attachment 2: Attachment 3: Attachment 4: Site Location Map Site Map Site Photographs Soil Gradation Curves Robert Alan Speed Regional Manager Rockledge Branch Office Attachment 5: Laboratory Analytical Results and Chain--of-Custody DocumentatiOn \\uesrock\dafa\reports\envrpls\envlOO1\51479 glsb evaluation rapoftdoc i. \ ATTACHMENT 1 SITE LOCATION MAP (. ( . • .( m ,YNIVERSAI ...... ftlEERING SCIENCES Grate Inlet Skfmmer Sox Evaluation South Breval'd Boulevard Cocoa Beach, Brevard County, Florida SITE LOCATION MAP ATTACHMENT 1 e (e e ATTACHMENT 2 SITE MAP ( .,( f I I I I I I I RESIDENTIAL CONDOMiNIUMS CONDOMINIUM DRIVEWAY c. LANDSCAPED MEDIUM RESIDENTIAL CONDOMINIUMS UNIVERSAL ENGtNSERING SCIENCES ) Q 8 Q Q Q I Q 8 , 8 I G I I , I I I , , , I I I , , , I I __ --.J---CONCRETE DRAINAGE SWALE SOUTH 8TH STREET Grate fntet Skimmer Box Evaluation South Brevard Boulevard Cocoa Beach, Brevard County. Florida SITE MAP RESIDENTIAL • ( ATTACHMENT 3 SITE PHOTOGRAPHS l I I I I ~ • . ' . • h • . . r', ">:: .:.~ :.: :<:«~::: ..... :.,:.,.,: >. ., . . . . ' .. ~ . Grate lDlet· at 600 South Brevard Avenue, 'Cocoa Beach Grate Inlet Skimmer Box Features Florida Type C Inlet storm Boom" Zip Tie ~ . Skimmer Flange is reinforced with' knitted 1808 :1:45° biaxial fiberglass It.'."": " "',1i''', 0\ '\: "W ,'"'' '>f' <,' '''''>', \';'"'' ''''~:,'''Ki:<[!''',,,'"<;:; ,,:Ii' "1"'",j 'J "',~~r'~rif,~f~~r~~ f;~~f~!·~.;il~r.f!~Ui~fPL4~ fNl~n(r: Pollutant R.emoval Testing for a Suntree Technologies Grate Inlet >!~'!f.}.~~'ll~.CJ •. ~.; [t !,~~t "1 ;':'.f. ,~" .~··.~~b::Yu. un~J ... ~!) cr~~n·PJ!~t~\:O~0.()t~~ .. :~. /" r~~~1~nfMH~f;;H~laf,) Skimmer Box ' SITE PHOtOGRAPHS Sediment Entering GISB • Sediment Trapped in GISB Pollutant Rbmoval Testing for a Suntree Technologies Grate Inlet Skimmer BOJ!: SITE PHOTOGRAl'HS • •• '.' .... . ,'" .... ~~. " ::> .. :,rrt "'. " . ': .' .~. : .. :.(':::~ .. '.::' ,~~~<: GISB Inserted into Inlet Pollutant R~val TeStirig for a Suntree Technologies Grate Inlet Skimmer Box SITE PHOTOGRAPHS • • • .Grass CHppiJ:lgs Entering GISB Sediment Testing Pollutant RemOval Testing for a Suntree Teehn:ologies Grate Inlet SldmmerBox SITE PHOTOGRAPHS • Grate Inlet Skimmer Box Evaluation NWC of South Brevard Avenue and South 8th Street ,:' Cocoa Beach. Brevard County, Florida SITE PHOTOGRAPHS NlA ( ( • cleaning. -Grate Inlet Skimmer Box Evaluation . NWC of South Brevard Avenue and South 8th Street . Cocoa Beach, Brevard Counw, Florida SITE PHOTOGRAPHS i .• ' \" cleaning. Grate Inlet Skimmer Box Evaluation . NWC of South Brevard Avenue and South 8th Street . Cocoa Beach, Brevard Coun1¥, Florida ; • SITE PHOTOGRAPHS DA RJlII'/NB: NlA 1013V1O'I 51479 Grate Inlet Skimmer Box Evaluation NWC of South Brevard Avenue and South 8th Street Cocoa Beach, Brevard County, Florida SITE PHOTOGRAPHS I I I '" . • / BY: I Grate Inlet Skimmer Box Evaluation NWC of South Brevard Avenue and South Slh street· Cocoa Beach. Brevard County, Florida SITE PHOTOGRAPHS 11:1 1\1 • IIIfA 101301111 i'UA 10130/01 ATTACHMENT 4 SOIL GRADATION CURVES • ~ I "" /. I J. .,' i _ r_f -" . " -. .. -.:.;r,,,",,,,,,,~~~~~ ...... , ... -~, UJ.~. SIEVE OI?ENiOOG OJ\IJ INCHES I U.S. SiEV~ NUMBERS ! lli'ifIOROMIiITER a 4 3 2 1.6 1 314 tl2 <W $ 4 G a 1@ 14 16 lID 30 40 00 71» tOO 14D aoo '100 U m~ U, n rnr B ~ : Ir 95 ; r : .' · · · • · I , · · • I · · 90 I I i" · · · , I • · · · · · 85 · '\ • · i : • : I ! I 80 · · · " I t I I · I I • : p 75 • · · · · · : · · • E • · : I I · I R 70 : I · • I · · · '\ : C · · · 1 I · : ~ 65 · \l I · . I I I I :i\ T 60 · · • • · I • ; : : , F · ! · : • · · I 55 · • : • I\" · · · N I : I · E50 I · .\ R : · I · · : 45 · . f , I· s · · -• V40 I -. i I I · ~35 · ; I · I · 'f \ • I · I I 30 I : . · · ~ I G · · · I · H 25 : : I I · T . · · . ! • · 20 I : · : : · · • · · I · · I 15 i · \ I · · · I 10 I · · · · , I I : i 5 · I I ! · i · 0 I 100 10 1 0.1 0.01. " 0.001 GRAIN SIZE IN MilliMETERS I COBBLES I ~VEL c:oarse_-& I coarse ( m;aPI line I SILT OR CLAY I Specimen Identification Classification MC% LL PL PI Cc Cu • 81 0.79 3.7 SEDIMENT 1 Speci~ldenmkation 0100 D60 030 D10 %Gravel %Sand %SIIt %Clay • 81 12.50 0.36 0.164 0.0961 10.7 88.0 1.4 314" 318" NO.4 NO. 10 NO. 40 NO. 60 NO. 100 NO. 200 94.3 $9.3 81.8 154.1 SO.3 25.5 1.4 .. CDient: CREECH ENGINEERING CUentNo: 331.86..002-01 4450 w. au GALLIE BOULEVARD Report No: 514~9 MELBOURNE FLORIDA 32934 /l)ate~ 10/9/01 !j2lroJ~: GAA T!§ HNUif ~KIl~m,'~R BOX EW\LIUIATOOINl ~R~VAM COWN1lif~ f~(»R!l©A ;OOL GRADATHON CURVES UJlrmiv®!i$~ Eougiou~en1rmg $csanc6Sg Ane. .I J , ., 1- - r Il.Il.S. ~gEVc OPENING lIN! RNCHES t U.S. SIEVE NUMBERS I G 4 S 21.ij1114~ 3 4 6 8 1@ ~4 'is 2D 3@ 4D 51) 10 ~OUJ 14G 200 'lUll 8 \3 ID , gOO "" ... " .. \ 9D 85 "" ~ 7S ~ ~ t·v ~ ~ .. e -) T ... , i~~ '" ,~ :: ~ I~: \ , W .... IE o7iI -I~ 30 \ ~= ft. \ --.\ '" ... '\ '". .-\ ., 0 10 1 a GRAIN SIZE IN MlLUMETERS COBBLES : c:oa JBifiA nne : c:oanre I ~I I me I Specimen Identification Classiftcation MC% LL Ie S2 SEDIMENT 2 SPEtClmen Identification D100 050 030 010 %Gravel i_I S2 12.50 1.61 0.237 0.1168 26.1 3/4" 31r NO.4 NO. 10 . NO.40 NO. 50 88.0 74.1 62.6 44.2 31.8 CHient: CREECH ENGINEERING Client No: 44SC We &AU GALUE BOUlEVAD Report lNo: MELBOURNE FLORIDA 32934 Date: IFJIfOJem: GRATE DNILET Sma_left BOX EVALYATUON e~ARD C©JUNfYD fLomDA SOIL GRADATION CURVES aJl!f6Bve~ail9 ~wBtiue@ll'liililtm S~HIl:l[m~. llimle. iiVfORIOMaeR . o. o.dot SILT OR CLAY PL Pf Ce, Cu 0.30 13.7 %Sand %Sllt %Clay. 72.4 1.7 NO. 100 NO. 200 14.7 1.7 33186..002..01 51419 1Q)/t/01 , ..• (. ! ( I " .. f ~ J .1 ATTACHMENT 5 LABORATORY ANALYTICAL RESULTS AND . CHAIN-Of-CUSTODY DO.CUMENTATION • Ir~ 1·· ~ . :1 J .. 1 PC&B lEn'VIHrorame!fQt~llaboratorle$9 ~rtn©" 210 Park Roadv Oviedcp Florida 32165 Phone: 401=359=1194 Fax: 401=359",1191 Client: Universal Engineering Scitilnc~ 820 Brevard Avenue Rockledge, FL 32955- Laboratory Reference Number: 201090199 Project Name: Inlet Skimmer Box Evaluation Project Numbar : Laboratory 10 Matrix CliantlO 201090199-1 Solid 0-1 Number Parameter Description 1 EPA 6010 Phosphorus by ICAP 1 EPA 9200/351.2 Total Nitrogen Conmm: JamesAdams Phone: (321) 638-0808 Chain of Custody: 24025 Status Oatemma Sampled RUN 09/2612001 14:20 PCBtlS E[f1Jvnlfonmenta~ Laboratories9 ~fl1Co 210 Park Road James Adams Universal Engineering Sciences 820 Brevard Avenue Rockledge, FL 32955- Oviedo, Fl 32165 .. 8801 401",359",7194 m (FAX) 407 .. 359 .. 7197 Case Narrative CASE NARRATIVE for Work Order: 201Q90199 Project Number: Project Name: Inlet Skimmer Box,Evaluation This Case Narrative Is a summary of events and/or problems encountered with this Work Order. . . ~alysis for TKN was performed by Environmental Science Corporation (E87487). • " Deftnltlon of Flags • ' DL III No surrogate result due to diJUlion or matrix interfenmce. , ( J = EsUmated YaIU4t. value not accurate. , L = ~scare higb. Actual value Is greaterthan value given • . \. Q a Sample analyZed beyond the aCcepted holding Ume. . '" T • Value reported Is fess th8{I the labOratorY method detection OmIt. " ,I '\ .I Ie j V = AnaIyte was boIh ~ed In tI1emethod blank and sample. pc&a EnVll'Onmemallaboratories, KlfI©. 210 Park Road Oviedo, Fl 32765-8801 . ',PHONE: 407-35907194 ~ Reference Number _~~nt Sample ID oatemme Sampled Sample Matrix (as RecelveCl> EPA 6010 Phosphorus, Total EPA 9200/351.2 Total Nitrogen 20100019e..1 G.-1 0912612001 14:20 Solid mg/kg 950 mg/kg 510 CliENT NAME: Universal Engineering SCIences PROJECT NAME: Inret SkimMer Box elYaluaii@i'il PROJECT NUMBER: DAlE RECEivED: 09126/2001 U = Undetected. The value preceedlng the 'U' Is the RL for the anaMe. Results reported on a Wet Weight basis. FDE? CompQAPP # S00134G 0 FDOH Certification # E83239 • ••• i . I· I J !. I .. 1 Analyte MethoiiEPA 8010A Phosphorus, Total tiC sa!CII: 2l'lili1oRCODti INORGANICS Spike Amount Sample ID: 20109020S01 10.0 mgJkg Lower· Sample Spike Percent Control Result Result Recovery Limit bateM!!: 10i61i2001 SAna!: 101D112OO1 Analii\i GG 70.0 78.1 81 70 Upper Control .Limit. 120 -,~:,,'~~?~~~lill ,_.4 IChcd~~.~st()dil· Il" ,r::AV' An7_'aCQ_",,.a,,, , • ."..., .,...,. -,...... • II .... ...,.,. ...... ------ . Work Order: 2f> " .'21 ~ Paae ___ @!" ~MPAN'/: \.l€-_ -S ANALYSIS REQUeSTED IDIWlG: ~n .-fiI':!.AIAIU'\ AV (cbit u( .:t-V1&.~ ~. 12-~S-~~ .@ -~ '~ .MPLEDSr. \A II. kF:S ~;V'\S:ON: .. ' \?_~) , 'm ~ ~~ ~~ 8 @Ne: --FAX: ---=:::;,,~ ~ . ,j !AI&! i I' Il!:' SAMPIU:RD DATEmME I I ,i I I ~-~ IC)/~ ID I /1'120 ,~ )( K '2 .... I I - . ~ ~ INQUISHEO BY DAT~ RECEtVEDB ~ DAIElTIM& PROJECT INFORMATION SAMPLE RECEIPT h~ ~ q?u,{(} I I'~ )" .. /~ ~tl;t;: PROJecrNAME: INCCT SIWM~ '&0)( t.v.AJ.I lA;n",J Total # of Containers ........ ----' r &. 2:, -, PROJECT.: : Chain of Custody S_ 3: SlTEAODIU£S$: ~ ~'l\<rl, h... Recv'd In Good Condition . , PROJECT~g ~~ IlJ.INSTRUCTlONStCOMI\1i:NTS: PO#: " INVOICE TO: • , . 'E/CONTRACT #: . , WHITE: PlDledPl/a .......... ... _ .. ---_ .. --''-'·&tf-.'·~vfrQniR.e.-. ntal . Ovieftff:_~ 4'J]. f "·"'''''~,-tJ IJ_ '....,=..;sr~:, Lli:llV." -',e. , ,'-, Page ... u_ , ' 'ki • " , I1IIPANV: 'l)C~', .. ,,' ' ANA1.YSIS REQUESTED g-:~~4\J ~ , I, ~]. ~<t eo,-~~ ~ ·.,n:.~'i:.CZ~_. ' ~~, ' '~ , , I~I t!FI.50aY: = ~~, "~ ,h ~' ~" 1£ ' 1-4 'I 8 'NIl!! ~-z.l.~~..oiM}f ,FAX: !':·~u. lrl!:!r'Of1tY : ~~ 1:;' '~' : ,-. ' , , .I' 1M'! B!X l' .1 -fl, SAiVilP~BD ,D'-"TEitlME I I I , • ;g . "", .• _.~ • I '.' ," '.~..0>4.:~~...,-=-..... '_-. !chain o •• ustodYi Work Order: cROIlb-,.~ A-7.~~ IDll% f ·1',( )(. X 2- ~. .. I' . .' . . " , , , : , 'iI\Q\!ISHED BV DATEITIME RECEIVED BY DATEITIME PROJECT INFORMATION SAMPLE RECEIPT fi-~~-;J. lbJI1/;)/ 1: 2/~~· /11111'/4/ PROJECT NAME! ./fJ.2tr" Total # of Containers "'--------- 2: PROJeCTlJ: ChWnofCumodySea~ .. ,. " . 3: IlTeADI)RUS: . I Recv'd In Good Condi«DoJ\l l\i. iNSTRUCOWNSl~MENTS: ( PROJECT MANAGER: -Q4.v[, {Art ... PO#: i INVOICE TO: , . 'reteON'mACT #: . I WHn1!l:'~"" ----_&.. . _. - " ___ H~_"''''''''''_V''H''''''''''''~''''--...........w ............. '-.... "'y.,, .- .; \' ]. 1 .I PC&I:J environmental UlbCi'a~ri6s, ~~rg. '210 Filiii'!< Roali! OViedo, Fl 32765-9801 • ·-"lONE: 407D3Sg..7194 (' ) Reference Numbell' . ant Sample 10 Dalemme Sampled Sample Matrix (as Received) EPA 6010 Phosphorus. Total EPA 92001351.2 Total Nitrogen U = Undetected. The value 201100168-1 G-2 10110120010:00: Solid mg/kg 2270 mglkg 905 Reviewed by ::"'., ="d6Jvlm~~~=~== 1 .1 .1 )e 1 PC&B Env!ronmentallaboratorles~ Inco 210 Park Road~ OViedo, florida 32765 Phone:401~59c1194 Fax:401~359a7191 Client: Universal Engineering Sciences 820 Brevard Avenue Rockledge, FL 329550 Laboratory Reference Number: 201100168 Project Name: Project Number: Laboratory ID Matrix ClIentlD 201'100168-1 Solid G~2 Number Parameter Description 1 EPA 6010 Phosphorus by leAP 1 EPA 92001351.2 Totat Nitrogen Contact: Bob Speed Phone: (32-1) 638-0808 Chain of Custody: 20344 status Datemme Sampled RUN 1011 O~001 '(. I \ : ....... • Analyle MfliiiOll: EPA 60101\ Phosphorus, Total QC BalJ:h: 2iKi11ilRC107 !NORGANICS Spike Amount Sample Spike Percent Result Result Recovery Dale Pf8JE 10119/2Oifi i5aleAnaJ: liii8l2OOi 178.0 199.0 105 Lower Control Limit AiiiiiiStGG 70 Upper Control ,Limit 120 , (e SITE IVALlJATION OF SUNTREE TICBNOLOGIES9 )Nee GRATE INLET SKIMMER BOXES e FOR DEBRIS, SEDIMENT, AND OIL & GREASE REMOVAL Reedy Creek Improvement District Planning &: ~gineering Department Eddie Snell, Compliance Specialist Stmnwater is DOW recopized as the leading SOUR'IO of poUuIioa to our remaining natuml water bodies in 1he United States, Development and urbaiIizaIiCll bave removed most of the natural ,,&lion and sediment trapping syStems povided by the environment Current 4evelopment must address this need through tho implementation of ~water tteatmenfs systems in die project design. Most of these systems prrlhrm Ie8SOll8bJ¥ weD,· if propedy designed, consfiUded, and maintained. Retrofit of older urban areas lacking these modem Sfmnwater systmns is a continually ~e . chaUenge. The Downtown Disney complex, formerly the Lake Buena Vista Shoppins Village, has several drainage basins with '1970's stoJmwater systems. 1bese Ql~ systems disehatgo direcily into the adjacent dminage canal with no pou. 1reafment Over time the aeeumulation of sediments, nutrients, intensive development,' and recreationaJientertainment pressures are contributing to water quality degradation. . . Whenever new development or =development ocwrs, 1ho ~water system is brought to current codeIpermit requirements. In the interim, several iIe8S are in need tbr rapid, effective, and economical improvement in the ~ty of its storm water discharge. SWltlee Teehnologies lncorporaled. located in Cape Canaveral, ~ manulictures stonnwater grato inlet skimmer boxes. They are made of a high quality fiberglass name, with stainless steel filter screens backed by heavy~ aluminum grating. Each. unit is custom made to accommodate various inlet sizes. A hydrocarbon absorption boom is attached to the top of the skimmer box fur petroleum, oil, and grease reDlOvat. These devices fit below the grate and catch 'sediment, debris, and petroleums, oils ~ greases. CleanmOut, maintenance, and performance reporting is provided by S~tree on a scheduled u,.s. The Reedy Creek Improvement District (ReID) selected, six (6) test sites in the Lake, Buena Vista area to evaluate the perfonnance of these units. One unit was placed in a curb inlet along Hotel Plaza BOulevard to trap lanckcapo leaf litter, sedimen~ and oil & grease from a high use roadway. Three (3) units wele placed in the backstage service area of the Rain Forest Cafe. Two (2) units were placed in the 'backstage service area of the McDonald's restaurant and Legos merchandise shop. After several field meetings, during which Suntree took extensive measurements, photos, and other documentation of each stolmwater drain, the Grate Inlet Skimmer Boxes were m~ufaetured and delivered for installation. AU units were installed without mishap approximately two weeks before the 1999 Christmas holiday season. The target time period for particle eawhment was one month. Mr. Henry and Tom HappeJ, Suntree Teclmologies, visited each site several times during the month to ensure that debris would not fill the units too soon. On Janumy 25,2000, Suntree serviced the six units. At each site, the-material captilred in the skimmer boxes was removed, measured, weighed, visually identified, photographed, and recorded. Some 'OOiw were slightly field modified for optimum penonnance. All (. '- • units performw as expec~ tremo~. M ~~ ~O pounds of debris hm each @f «he six sites. Th@ oompomtioo 4)f debris vaned considerably. . The Hotel Plaza (roadway) site was 900,4 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 500A, sediment The middle inlet was 60 %sediment and 30 % leaf litter (10% miscellaneous). The inlet closest to the lake was 95% sediment and 5% leaf litter. The two sites at the McDonaldsJLegos area were similar to each other. The site closest to the lake was 95% sediment and 5% leaf litter. The site closest to the entrance' gate was 98% litter sediment and 2% leaf litter. t ,. ,t I .~* .j , .'. This composition is indieative of the human activities and drainage flow patterns of that site. Backstage areas in the Walt Disney World Resort receive an artificial min event each night during cleaning operations. This washes a continual flow over the intpervious site, washing all materials intO the stonnwater system. Municipalities in Brevard, Volusia and Dade counties have successfully used inlet skimmers in Florida. RCID partnered with Walt Disney _gineering (WOI) Research and Development to coordinate some basic chemical sampling for pollutant removal efficiency determination. Mr. Craig Duxbury, WDI, provided technical support and guidance for this. An ingeniously simple device was fabricated by Suntree to allow sampling of the First Flush of water going into the uni1s and ultimately coming out of the' skimmer boxes. ' . • ---.----....-----.---' CoIleclId samples were jlIIlCCISIJeIi.'" lII8Iyaod by die· RClJ) BuvironnmaI Services Laboratory. Analysis. parameter were: Ammonia, Chemical Oxygen Demand, Fecal 'ColifOJDl (MPN), W1trite and Nitrate, Total' IQeldabl Nitrog~ on and Grease. Total Phosphate, Suspended. Solids, and Metals. Analysis results are presented in the following table: Pollutant % ------' ANALYSiS LOCATION IL.A8 NO. VAWS • UNITS SAM.DATE Change Oilanle Ammonia, Salicylate RF-IN 1646 0.38 mgll CJ9.FeI>OO 0.14 Ammonia, Salicylate RF-Our 1646 0.23 mgII O9-feb.OO Ammonia, SalJQYiate RF'()UT-I 16.46 0.25 mgII 09-FeIJ.OO Chemical Oxygen Demand RF-IN 1846 2670 mgII CJ9..Feb-OO 1036 Chemical Oxygen Demand RF"()UT 1646 1780 mgII O9-Feb-OO Chemlcaf Oxygen Demand RF'()UT-I 1848 1490 mgII Q8..FeboOO CoNform, Fecal MPN RF-IN 1646 1800 #100 ml 09-feb.00 -934GO Coliform, Fecal MPN RF"()UT 1848 180,000 tIOO rnl O9-Feb-OO CoHform. Fecal MPN RFoOUT-I 1846 30,000 #100 ml 09-feb.00 NItrate and Nitrite RF-IN 1846 0.08 mgII 09-FeboOO 0.035 Nitrate and Nitrite RF-oUT 1848 0.04 mgII 08..fel>OO Nitrate and NItrIte RF..C)UT-I 1846 0.01 mgII 09-Feb000 Nitrogen, Total KjeldahJ RF-IN . 1846 24.3 mgII, ()9..F'eI>OO 13.66 Nitrogen, Total KjeIdahI RF-OUT 1648 10.4 mgII oa.Feb-OO Nitrogen, Total Kjaldahl RF'()UT-I 1646 11.1 mgII f».Feb-OO 011 and Grease RF..JN 1846 526 . mgII Q9..Feb.QO 283 Pollutant removal efficiencies . averaged about SO% for all pammeters tested. The minimal removal was 31% for ~ and the maximum removal was 74% for Suspcndecl So1i~ 31% Coliform bacteria were not effeetiyely removed by the skimmer boxes,. aJtbouab. tltey are not designed to provide water dlsinii:ction. Oil and aa. are at'oad SOUl'Cle for bacteria and reduction of thii pollutant . should provide some "cot OD bacterial numbers. • ". ( , • Pollutant Removal Efficiency 80% ! I I 1 10% + I r . 60% j." .... _,,-..1 IC1 50% ,.t... o j 11 i 40% ,!. fI. 30% !. . 20% i 0% ! .. ,. % Change Parameter I Ammonia, Salicylate • Chemical Oxygen Demand • NItrate and Nilrite [] Nitrogen, Totil KJeldahl • Oil and Grease • Phosphate, Total • Wads, Suspender • • • Pm~t Construction BMPs Mmilmtemmce Cost Responsibilities The Following are Privately Maintained and will be conducted by Franz-Yut EI Camino Real, LLC: 1. All On-Site driveways and parking lots 2. Periodic street sweeping *(Parking Lot Sweeping -$3,500.00) 3. Trash storage areas will be properly designed per City of Carlsbad's Standard Drawings. Trash will be collected either weekly or bi-weekly (depending on arrangement with waste disposal company) by Waste Management. *(Trash collection {each lot} -$1,300.00,) 4. All vegetated swales, planted slopes and landscaped areas (Landscape/mowing- $8,505.00, Irrigation -$3,600.00) 5. Private storm drain system/detention basin *(Storm drainjetting/basin maintenance- $3,000.00) *Costs shown arefrom Franz-Yut EI Camino Real, LLC, 2006 anticipated annual maintenance cost for Cassia professional Offices. Individual tentants are held accountable for a percentage of the annual costs determined by F'ranz-Yut El Camino Real, LLC. City Maintained: 1. The main line of the existing storm drainage system located in EI Camino Real is public and thus will be maintained by the City of Carlsbad. 2. Public Water and Sewer Systems are the responsibility of the Carlsbad Municipal Water District and City of Carlsbad to maintain .