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tti Aquifer Cleanup Bioremediation can restore organically contaminated aquifers. continued from page 38 altered, meaning the pump-and-treat underway at sites with contaminant been estimated to reduce the time for system can be operated at a lower flow plumes ranging from less than an acre aquifer restoration by 50 percent. For a rate than if surface water was deliv- to more than a mile in length and pump-and-treat system operating longer ered to the aquifer. containing such diverse contaminants than 10 years(which is currently typical), Where there are no downgradient as gasoline, diesel fuel, jet fuel, creo- the savings involved by including in situ issues, it may be possible simply to sote, pentachlorophenol and chlorin- bioremediation can be substantial. deliver appropriately amended water. ated solvents. Closed loop systems offer the primary to the aquifer without the need for Because the conventional technolo- remedial advantage that no treated water plume containment. Although these in gies have failed to produce timely needs to be discharged to a sanitary sewer situ bioremediation systems are the aquifer restoration, the time is ripe to or surface water body. However, in some simplest and most cost-effective sys- evaluate fully in situ bioremediation cases, regulations prohibit re-injection or tems to install and operate, they are for aquifer treatment. This technology re-infiltration of formerly contaminated allowed in few circumstances. could prove to be extremely useful in groundwater, even if it has been satisfac- In terms of engineering considera- restoring organically contaminated torily treated. In these cases, the tions, it is important during the reme- aquifers in a timely fashion. CD extracted groundwater must be dis- dial investigation of the aquifer to charged properly, and the water cannot gather information that will be vital to Acknowledgements The following people be used to enhance in situ biodegradation the proper design of the in situ biore- contributed to the completion ofthis article: of the aquifer contaminants. Instead, it mediation system components_ The Raymond Loehr, University of Texas; may bpossible to take water from information required involves hydroge- Evan Nyer, Geraghty & Miller, James ye p Spain, U.S. Air Force; C.H. Ward, Rice another source, amend it appropriately ological analyses of the contaminated University; John Wilson, USEPA's Robert and deliver it into the aquifer's contami- aquifer and chemical analyses of the S. Kerr Environmental Research Labora- nant source area(s). aquifer sediments and the groundwater. tory; and Desma Hogg, Pelin Gtirkan, J. If a surface water body is used for the In situ bioremediation is an exciting, Robert Doyle, Linda Niemeyer and Daniel Eldredge, a11 of Woodward-Clyde. � source of delivered water, the net flux of innovative approach that holds great } groundwater flow through the contami- promise for addressing aquifer ` Want source area will be increased, per contamination problems. Variations of uirharl Q Pionowski it an Associare and Chairman of dv k haps to a significant level. In such cases, the technologyhave been field-tested Diego,Ciaf.n Group with cdvEWooin r.e didgt Co F mtn in kn Diego,Ca& He has beat acdvr in rrr deli rt,im luautradorti I the pump-and-treat system may have to at several sites on a pilot scale and the operation and evaluation of biorente ikdoa rprent for tine be operated at a higher extraction rate to results of the tests have been encour- deconaminaaon for approximefely 10 yeam control the contaminant plume and pre- aging. Full-scale field-testing is vent additional migration of the contami- nants. The same may be true if munici- pally supplied water is used as the water MONITORING PIPE & ACCESSORIES c . source. FOR THE Problems With Chlorine PETROLEUM, ENVIRONMENTAL & f An additional concern with using WATER WELL INDUSTRIES municipally supplied water is that it Accessories for > ng of probably contains chlorine. The - undergzo'rnd stn�n biocidal nature of chlorine can have a negative impact on the performance of Steel;,, a en6tasiare - I an in situ bioremediation program by �� `fhred` us # tee art casing affecting the microbial community deleteriously. If a municipal water Sam lin jdevices source is used, the water must be We ..M dechlorinated before it is delivered to _ Points- 31!111Z the aquifer. s An alternative water supply that Custom tamfo;' can be used for iniection/infiltration is ATLANTIC 9MFG. INC. uncontaminated groundwater :la srpaa-n Htton,of I"W extracted from the aquifer upgradient 302 684-3197 AZ 4` from the head of the contaminant TE[I FAX. 302-684-0643 plume. A primary advantage of this < approach is that the net flux of groundwater through the contami-' nated zone of the aquifer will not be Circle 24 on cart!. 49 MAY 1992