NWEC STORMWATER MANAGEMENT FOR LARGE SITES S O G O G S S
AND MAJOR POLLUTANT LOADS
GETTING TO COMPLIANCE-BEYOND OPERATIONAL AND BEYOND OPERATIONAL AND
STRUCTURAL BMP’SSTRUCTURAL BMP S
Neil Alongi, P.E. – Maul Foster & AlongiDecember 6, 2010
TOPICS
Large Site ChallengesLarge Site ChallengesFlow Quantity and RateMultiple OutfallsMultiple OutfallsMultiple Problem Contaminants
Contaminant IssuesContaminant IssuesTreatment and Disposal Options
LARGE SITE STORMWATER CHALLENGESLarge site = High volumes and flow rates
CHALLENGESLarge site High volumes and flow rates
High cost to manage and treatSite space availability usually a challengeSite space availability usually a challenge
LARGE SITE STORMWATER CHALLENGESLarge site can mean multiple outfalls
CHALLENGESLarge site can mean multiple outfalls
Multiple monitoringpoints = more p
chances fornon-complianceP t ti l hi h t Potential high cost to combine flows
LARGE SITE STORMWATER CHALLENGESDiverse operations = multiple contaminants
CHALLENGESDiverse operations multiple contaminants
May mean more treatment challenges
LARGE SITE QUANTITY CONTROL
Large site with excess property Large site with excess property open storage + infiltration = cheapest solution
LARGE SITE QUANTITY CONTROL
Large site without much space = above-Large site without much space aboveground storage reservoirs + high rate pump stationp pStorage volume and rate of treatment are closely relatedy
Large storage with low treatment = concern with longer storm event durationContinuous stormwater models best suited for evaluating design alternatives
ABOVE GROUND STORAGE, PUMPING & FLOW CONTROLPUMPING & FLOW CONTROL
LARGE SITE QUANTITY CONTROL
Large site with very little space = Large site with very little space underground storage + high rate treatment systemy
Underground storage = high costShifts costs to high rate treatment systemsCost balance between these two components
LARGE PUMP STATION + UNDERGROUND STORAGEUNDERGROUND STORAGE
LARGE SITE CONTAMINATION
Like any site, must first characterize Like any site, must first characterize contamination
Check permit parametersp pAdd other parameters that may interfere with successful treatmentBreak down site by operational activities
Diverse contamination typesMay mean more than one type of treatment
to meet permit benchmarks
LARGE SITE CONTAMINATION
Most problematic contaminant typesMost problematic contaminant typesMetals, especially dissolved metalsHigh turbidityHigh turbidityChemical Oxygen Demand (COD)Biological Oxygen Demand (BOD)g yg ( )E. ColiNutrients (Phosphorus, Nitrate, Nitrite)( p )
TREATMENT TECHNOLOGIES
Constructed vegetated flow-thru systems Constructed vegetated flow thru systems Bioretention filtrationPolymer enhanced filtrationPolymer – enhanced filtrationAdsorptive Filtration El t l tiElectrocoagulationIon exchangeMultiple stage treatment – most complex and expensive
CONSTRUCTED WETLAND TREATMENT
Space intensive
TREATMENT
Space intensiveLow MaintenancePerformance relative to detention
BIORETENTION FILTRATION
“Biomass retention of pollutants”Biomass retention of pollutantsNatural and manufactured mediaWide variety of designsAdsorptiveAdsorptivefiltrationmediamediaapplication
POLYMER-ENHANCED FILTRATION
Most commonly used is chitosan Most commonly used is chitosan Low toxicityCommon system for const. sitesAdaptable to permanent systemsAdaptable to permanent systemsHigh treatment capacityGood for large sites with high turbidityy
Adsorptive Filtration
Reactive media with targeted
p
Reactive media with targeted contaminant removal
fi iMay first need settling or sand filtration to remove larger particlesg pMedia for metals, coliform, nutrientsnutrientsIn vessel or as planting media
ADSORPTIVE MEDIA
ELECTROCOAGULATION
Effective for a variety but not all Effective for a variety, but not all, contaminants
i iHigh capital cost-moderate O& MMetal removal rates around 90%e a e o a a es a ou d 90%Treatment train usually includes settling and filtrationsettling and filtration
ELECTROCOAGULATION
ION EXCHANGE
Tested in Ecology Boatyard studyTested in Ecology Boatyard studyAppeared effectiveNot much information available regarding costs and full scale useega d g cos s a d u sca e use
MULTIPLE STAGE TREATMENT
Single advanced treatment is Single advanced treatment is expensive
i iMultiple stage treatment is prohibitively expensive in most p y pcases
MULTIPLE STAGE TREATMENT
One of MFA’s advanced One of MFA s advanced treatment system designs includes
Pre-settlingElectrocoagulationgSettlingSand FiltrationSand FiltrationMicron-level cartridge filtration
DISPOSAL OPTIONS
Receiving Water BodiesReceiving Water BodiesDirect di hdischargeDiffuser outfall for enhanced enhanced dilution
DISPOSAL OPTIONS
Municipal Storm Sewer Municipal Storm Sewer –potential dilutionpMunicipal Sanitary Sewer –
t ti l hi h li itpotential higher limitsInfiltration – potential for no Infiltration – potential for no monitoring except bypass
QUESTIONS?