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?

Thank You

Neil Alongi P ENeil Alongi, P.E.nalongi@maulfoster.com360.694.2691