Hydrograph, Pollutograph, and Thermograph Analysis of Deiced ...

Hydrograph, Pollutograph, andThermograph Analysis ofDeiced Highway DrainageD.W. Ostendorf, E.S. Hinlein, and C. RotaruEnvironmental and Water Resources Engineering ProgramCivil and Environmental Engineering DepartmentUniversity of Massachusetts, Amherstostendorf@ecs.umass.eduInternational Conference onEnvironmental Science and TechnologyAmerican Academy of SciencesHouston, TX June 29, 2012

Overview• Institutional and physical setting• Highway drainage system, vadose zone, aquifer• Linear systems and instantaneous unit hydrographs• Specific conductivity as deicing agent surrogate• Temperature as possible third signal• Conclusions

Hobbs Brook Reservoir SubbasinPublic water supply, Cambridge Water Department

Interstate 95 Right of WayInterstate 95 right ofway (Route 128),maintained byMassachusetts DOT

Deicing Agent ApplicationRoad salt (NaCl) and prewetting (MgCl 2 ) to deice the pavement

Runoff from Closed Drainage SystemCurbs, catchbasins, storm sewers: Q R , μ R

Continuous Discharge and SpecificConductivityFlow meter, potentiometric probe, and thermometer at15 minute frequency or faster. Leads to telemetry….

Telemetry and MaintenanceLocal power and dedicated landline. To USGS online website…..

USGS

Rights of Way and WatershedsStakeholders and Agencies• Drivers demand * bare pavement and unimpeded drivingspeeds under all conditions.• Deicing agents must interact with solid precipitation onthe pavement texture.• Drinking water users demand * low ion concentrations insurface water supply reservoir.• Four cooperating agencies—MassDOT (I95 deicing),Cambridge Water Department (water supply), USGS(data acquisition), UMass (analysis)• *these are Boston drivers and Harvard users

Hydrographs-Conservation of Water MassDischarge is superposition of runoff (closed drainagesystem, interflow (vadose zone), and baseflow (aquifer)QQRBaseflow and interflow are constant during storm.Runoff is absent and baseflow is constant duringinterstorm period. Runoff and interflow output are IUHconvolutions of precipitation (P) inputQIQBQR,ICR,IAR,It P( )exp[0R, I( t)] d

RunoffVery intense storm of 6-7September 2008.Calibrates the closeddrainage system decayconstant Q~Q R R1.8x104s1Hour of 6-7 September 2008IUH holds for all storms.Note the high dischargeresponse to the stormCalibrated value implies a laminar sheet flow depth of 0.5 mm,based on a 0.01 pavement slope and a 100 m distancebetween catch basins. Note the hourly response time.

InterflowVery intense storm of 15June 2006, followed by 7day interstorm period.Calibrates the vadosezone decay constantDays in June 200661 I 4.6x10sThis holds for all storms.Note the semilog plot of thehydrograph Q I

Andover I495/I93 AutosamplerSome highway sites have autosamplers along with thecontinuous probes…………..

Ion Chromatograph for Cl -Water samples may be analyzed for major cations (ICP),anions (IC, TOC), and charge balance………..

SpC to Chloride CorrelationCouples dissolved pollutographs to solid deicing agent dissolution,if chloride is the major anionic constituent (NaCl, MgCl 2 , CaCl 2 )

Pollutographs-Conservation of SpC(Advective) flux F as product of specific conductivityand (water) dischargeFR FI FB QBaseflow flux constant during storm (Q B μ B ). Interflowflux from plowed drift (Q I μ I ). Runoff flux due todissolution of (residual) deicing agents on thepavement (μ P ) into precipitationFRCRARt P( ) ( )exp[ ( t0PR)] dWater and contaminant mass transport are coupled

Deicing Agent Dissolution KineticsElemental volume in the mm scale pavement texture (ζ)ddtPPP Zero order source strength (ω) depends on granule size,which shrinks seasonally. Kinetics determine μ P , F R

Specific Conductivity Pollutographs 5x10m mScm sWinter SpC rises to 7 mS/cm with first flush of runoff. Strongsource and comparable interflow and baseflow concentrations.Summer SpC diluted by runoff, recovers to baseflow asymptote.Weak source, weak interflow, constant (and appreciable!)baseflow concentrations.4mS I 1. 24 ; B 2.04cm 2x105mScmm mScm smS I 0. 062 ; B 2.24cmmScm

Thermographs-Conservation of EnergySimplest approach, just mixes the temperature streamsTQRTR QITQBaseflow and interflow temperatures vary sinusoidallyto reflect diffusive heat transfer into subsurfaceTITBTSIQBT T sin( tB )Runoff varies linearly to mimic cooling (heating) on roadTRTRO tJust a simple start: no phase change, meteorology, etc.

June 2006Hyetograph (P), hydrograph(Q), pollutograph (μ), andthermograph (T). Runoffand subsurface are hotTRO 293 K;T 288SKThe summer runoffthermograph isreasonably modeled.Subsurface thermographis periodic.

March 2006Hyetograph (P), hydrograph(Q), pollutograph (μ), andthermograph (T). Runoffand subsurface are coldTRO 281 K;T 277The winter runoffthermograph is poorlymodeled, thoughsubsurface thermographis periodic.SKThermograph modeldoesn’t work. Yet.

Acknowledgments• MassDOT/UMass ISA 56565 funding, with USGSsubcontract to UMass for instrument maintenance andUSGS website management.• Cambridge Water Department logistical support.• Nonetheless, the analyses and conclusions are onlyby the Authors. Not a specification or regulation ofany Agency, local, state, or federal………….

Conclusions• Classical linear theory describes hydrographs assingle linear reservoirs for closed drainage, vadosezone, and aquifer. Simple, accurate, and physicallyplausible decay constants.• Surface runoff pollutograph dominate specificconductivity in winter, much weaker in summer—baseflow is stable and appreciable year round.• Hydrograph and specific conductivity pollutographanalyses are coupled and well established—anduseful for deicing agent fate and transport modeling.• Thermograph model too simple to recover winterrunoff data. As yet unproven.

References (Proceedings Paper)• Gelhar, L.W. and J.L. Wilson, 1974. “Groundwater quality modeling”. Groundwater,12(6): 399-408.• Granato, G.E. and K.P. Smith, 1999. “Estimating concentrations of road saltconstituents in highway runoff from measurements of specific conductance”. WRIRept. 99-4077. USGS, Northborough, MA, 22 pp.• Nash, J.E., 1959. “Systematic determination of unit hydrograph parameters”. J.Geophys. Res., 64(1): 111-115.• Ostendorf, D.W., D.C. Peeling, T.J. Mitchell, and S.J. Pollock, 2001. “Chloridepersistence in a deiced access road drainage system”. J. Environ. Qual., 30(5):1756-1770.• Ostendorf, D.W., E.S. Hinlein, D.P. Ahlfeld, and J.T. DeJong, 2006. “Calibratedmodels of deicing agent solids, pavement texture, and specific conductivity ofhighway runoff”. J. Environ. Eng., 132(12): 1562-1571.• Smith, K.P., 2007. “Hydrologic, water quality, and meteorological data for theCambridge, MA, drinking water source area, water year 2005”. OF Rept. 07-1049.USGS, Reston, VA, 119 pp.• Waldron, M.C. and G.C. Bent, 2001. “Factors affecting reservoir and stream waterquality in the Cambridge, MA drinking water source area and implications forsource water protection”. WRI Rept. 00-4262. USGS, Northborough, MA, 89 pp.