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Combining Remedies/Treatment Trains for NAPL SiteRemediationExploiting Synergies to Reduce Costs/ImprovePerformance/Increase CertaintyFederal Remediation Technologies RoundtableMay 2007Jim CummingsTIFSD/OSWER/USEPA

Historical Perspective onCombining Remedies Earliest – Some talk, little action (like the weather, everyonetalked about ‘treatment trains ’) Early – Limited use, mostly ad hoc Practitioners noticed something ‘interesting’ during/after remedyimplementation EXAMPLE: Electrical Resistance Heating (ERH) to treat methylenechloride––Contaminants went away but not recovered, - ?Explanation: Greatly increased hydrolysis rates at 70 C More Recently (post 2003)- (Somewhat) Moreupfront/purposeful Practice Still WAY out ahead of the Research (SERDP/ESTCPto the rescue )

Combinations Temporal – Adjust/change technologies atappropriate changeover points Spatial– Treat different zones withdifferent technology(s)- ‘Hot Spots’/’Warm Spots’/DissolvedPhase ‘Misc.’- E.G., Maximize in-situ destruction(hydrolysis) to reduce/eliminateneed for off-gas treatmentsystems

’(Back-end)

‘Priming’ - Zappi et al ‘Chemical Oxidation Priming for Enhancing PollutantRemoval in Soils by Biological Treatment’ – ACS Nat’lMeeting, 2002 ‘ChemicalPrimed Enhanced Bioremediation ofPetroleum Hydrocarbon Contaminated Sediments’ –MS-AL SeaGrant Program Review Meeting U of Miss,2002 ‘Integration of Chemical-Oxidation andBiotreatment for Removal of TNT’ – FinalReport to Army Research Office, 2003

IMPORTANT NOTE: ‘Polishing’Doesn’t Have to Come Last Michigan PHC site– Combination of Chemox Bio implementedfollowing 12 years of MNA BTEX plume shrank, but zone still RAO’s Trimethylbenzene recalitrant to Bio alone

Possible In Situ TechnologyCombinations Thermal ChemicalThermal BioChemOx BioChemox ChemoxSurfactant/Cosolvent BioSurfactant ChemOxAbiotic (Nano-Fe/ZVI) ?

Seers (?) ‘ it is now clear to many that chemicaloxidation is best coupled withaccelerated bioremediation for moresuccessful site management.’– Regenesis ReGenOx Product and Design Manual

Seers (cont.)

Navy ERP Manual 9.2.3 Flexible ROD The goal of a flexible ROD is to allowmodifications in the remedial approach Theseare often required to address uncertainties andchanging site conditions that typically areencountered during implementation of aremedy as additional site and performancedata are collected

Navy ERP Manual (cont.) It is important that the language used in theremedy description allows for flexibility intechnology transition and unit processselection The remedy should also address the treatmenttrain planned for remedial technologies, such asa transition from contaminant source areatreatment to MNA for the dissolved phase plume

Excerpt from NAVFAC ReportExecutive Summary “In addition to volatilization and steamstripping, enhanced biodegradation andother abiotic reactions at elevatedtemperatures were an active mechanism atall five sites. Degradation of some components of organicmatter at elevated temperatures and theconsequent increase in the availability of acarbon source is advantageous forbioremediation.” (i.e., beneficialdowngradient effects)

Charleston Navy Facility ERHPerformance Initial Results - 79% VOC reduction(dissolved phase) versus 95% target– Electrode spacing an issue, also soil drying,acetone generation Subsequent monitoring data showscontinued reduction in contaminant levels(Courtesy Dean Williamson, CH2M Hill)

Thermal Bio Evidence of biodegradation followingElectrical Resistance Heating (ERH) atCharleston Navy Facility Dry Cleaner Downgradient reduction trends alsopartly attributable to (slow) flow ofclean groundwater through treatedzone

Thermal Chemical Dozens of Steam-activated Persulfate Cleanups Cost Information:– steam subsurface to 65 deg C 22/cu yd– steam subsurface to 45 deg C 13/ cu yd– persulfate @ 1g/kg ox demand 19/cu yd– persulfate @ 2 g/kg ox demand 28/ cu yd

Steam-ActivatedPersulfateField Results

Chlorinated SolventsLocation1,1 DCE (ug/l)Scotland Neck, NC 230,000/460Garner, NC81,700/0.8LocationCobb County, GA1,1,1 TCA 5,100/ 2.63.2/ 0.05

Combined Surfactant/ChemicalOxidationLNAPL Contamination(Petroleum Hydrocarbons)

Bixby Underground Storage TankSite, Bixby, OK (LNAPL) NAPL: mixed gasoline andkeroseneGeology: fine sandFree product: 0.5 to 2.2 ft,extent 120 ft x 85 ft Surfactant flushing:Mobilization, 0.94 wt%,120,000 gallons (1.5 PV)over 13 days Polishing: 0.4 wt% Fenton’sReagent, 130,000 gallonsover 6 daysBixby UST Site

Bixby UST Site (cont.) No free product observed after surfactantflushing Post surfactant flushing: GW Benzeneconc. 50 ug/L to 20 mg/L Post chem ox polishing: GW Benzeneconc. ND to 1.8 mg/L (SSTL 5.6 mg/L) Project completed in 2.5 months

The Bio-Augmentation Pendulum1995 – No Way - Predation, etc, etc.2005 – Why Not?- “It’s so cheap ”

Bioaugmentation Some vendors report bio-augmentingas a matter of course – i.e., withouteven looking for DehallococidesEthogenes (DHE)

(Highly) ‘Recommended Reading’:BIOAUGMENTATION FORCHLORINATED SOLVENTREMEDIATIONHans StrooSERDP Partners ConferenceDecember 2005

Enhanced Reductive Dechlorination There are a variety of possible electrondonors – vegetable oil, molasses,whey, beer wastes, chitin, HRC Electron Donor appropriatenessappears to be site specific

DESIGN CONSIDERATIONSFOR REMEDIATION BYSTEAM AND IRON ENHANCEDIN-SITU SOIL MIXINGThe 5th InternationalConference onRemediation ofChlorinated andRecalcitrantCompounds25 May 2006Monterey, CAJohn P. MatthewsPatrick AFB, FL

SPACE LAUNCH COMPLEX 15 Launch StandTreatment 313 treatment cells20 ft to 55 ft bgs1 March – 3 October 2004Estimated TCE MassRemoved: 3,800 – 6,100lbEstimated VOC MassRemoved: 9,700 – 12,600lbDoes not include in-situbreakdown with ZVIEstimated TreatmentVolume: 26,500 cubicyards (minus overlap)

LESSONS LEARNED & FUTURE SITES Lessons Learned from Space Launch Complex 15 Change from 10 foot auger to 8 foot auger Upgrade data acquisition system Increase number of gas chromatographs – runcontinuously Work outer ring first – then step out from “hot” cells Mix zero-valent iron slurry to lowest depth along outerring Tweaked treatment protocol to spend more time on highcontaminated cells and less time on low-concentrationcellsFuture Cape Canaveral AFS SitesSecurity Police Confidence Course (145 cells)Facility 1381 (892 cells)

Issues Impact of Active Agents – Heat/Oxidants onMico-organisms–– Effects of Oxidants on Thermal SystemComponents– Within limits, effects seem tolerable/reversibleDowngradient zones are not affected – In fact,appear to benefit (e.g, Ft Lewis, Wash.)May require corrosion resistant materialsWhether costs will be synergistic oradditive? – especially with multiple vendors

Issues Presumption of Certainty in DecisionDocuments for Sites Subject toFed’l/State Oversight– But NOTE: Trend toward more flexible,adaptive approaches and combinedremedy specifications in RODs

Issues (cont.) Combined Remedies may beparticularly suitable for early-/mid-90’sRODs specifying Pump and Treat atsite w/ likely NAPL contamination

Combined Remedy RODs Pemaco NPL (solvent) site, Maywood,Ca – STATUS; Installation underway– Electrical Resistance Heating (ERH) in hotspot at 35-95’ bgs– Enhanced vacuum extraction in vadose zone– Possible use of In Situ ChemOx, EnhancedBio, MNA in downgradient zones

Addtl Recent NPL Site CombinedRemedy RODs Brunswick Wood site ROD– Stabilization/Solidification, Slurry Walls, andIn-situ Chemical Oxidation TEXWOOD site ROD– insitu S/S, open slurry walls, In-situ ChemicalOxidation, and MNA

Grants, NM Solvent NPL site RODPROBLEM COMPONENTREMEDYVapor IntrusionMitigationSource AreasIn Situ Thermal TreatmentShallow Plume Core and Hot SpotISCO followon ERDShallow GW Plume peripheryERD Bio-BarrierDeeper GW PlumeERD Bio-barrier

Grants NM ROD (cont.) Remedial Flexibility– “EPA will evaluate the site conditions todetermine if MNA is a viable remedialalternative after the first 5-year review andafter source control has been established inthe source area and the shallow GWplume ”

Challenges Convincing decision-makers that‘combined remedies’ is not aeuphemism for ‘blank check’ Whether single technologies orcombinations, we still have work to doin the area of in situ process control

Desired End State/Least CostSolutions Adequate Use of Robust Source TermRemoval Technologies Timely transition to cost-effective‘polishing’ step(s) Reduce/Eliminate Need for Pump andTreat Appropriate Reliance on MonitoredNatural Attenuation (MNA)

‘Holistic’ Remedy: Partial Mass Removal via InSitu ChemOx (ISCO) Enhanced NaturalAttenuationNortheast US former Manufactured Gas Plant(MGP)DNAPLSourceZone ISCONOTES:SpargeCurtain/Barrierfor residualmass flux fromsourceAir Injection at Toe andMidpoint of Plume (ENA)1) Plume mgmt necessary because contamination has reached residential wells2) ISCO pilot completed. Consultant analyzing results

Combined Remedies - ClosingThoughts Flexible, Adaptive Implementation is aCrucial Component of CombiningRemedies For NAPL Sites

Combined Remedies - ClosingThoughts (Cont.) System installation and operation can providevaluable information on actual subsurfaceconditions and contaminant distribution– “RD/RA - Just the next phase of Site Characterization ”– “NAPL sources begin to reveal themselves as theremediation progresses ” Consultant at PittsburghEnvl Restoration Conference

Another Way of Thinking About‘Performance-Based’ What would a regulatory framework look likethat put a number on ‘reasonable timeframe ’ as envisioned by the NCP (e.g. 30years), and allowed consultants to designtreatment trains to meet that timeframe? Hint: Tools like ‘Natural AttenuationSoftware’ will be part of the package

Bixby Underground Storage Tank Site, Bixby, OK (LNAPL) NAPL: mixed gasoline and kerosene Geology: fine sand Free product: 0.5 to 2.2 ft, extent 120 ft x 85 ft Surfactant flushing: Mobilization, 0.94 wt%, 120,000 gallons (1.5 PV) over 13 days Polishing: 0.4 wt% Fen