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00 TABLE 1.Groundwater Geochemical Partnlnetel's. 14100-3 Units 5/1/1.000 8/10/2000 11/10/2006-- 2/.5/2001 5/23/2001 10/29/21101 Ethene nng/L NS 0,01 NS 0.09 0.002 N5_._ hthauc m2/1. NS <0.01 NS 0.04 0.002 NS Methnne mg/L NS 0.07 NS 1.19 0.092 NS Tubd Acids mg/L NS 92 NS 54.3 <4.1 NS ORP roy 97 -201 -299 X47 -307 -R4 Mw-10 Units 5/1/2000 8/10/2000 11/10/2000 2/5/2001 5/23/2001 10/29/2001 Ethene mg,L NS <0.02 NS <0.02 <O.Q06 NS Ethene Ing/L NS <0.02 NS <0.02 <0.006 NS Methane mg1t. NS 0.33 NS 2.12 2.96 NS Toted Acids mgjt, NS 163 NS 104.7 27.3 NS ORP 111V -39 -151 -273 -137 -91 -75 Ns= 1101 sampled CONCLUSIONS Injection of ITRC into shallow aquifers utilizing direct push tecln1I010gy can he a cost effective remedial technology for dry cleaner facilities contaminaled by PCI; and its degradation products. Contaminant and geochemical data presented from this case study of a dry cleaner facility in Arlington,Texas clearly demonstrate that the HRC injected into this shallow, perched aquifer aided in creating the requisite anaerobic subsurface environment and provided the hydrogen required for efficient reductive dechlorination which has significantly reduced contaminant concentrations within a year of application. As a direct result of I1RC application, this site has received a Conditional Certifcale of Completion G"om the TNRCC V011,111tany Cleanup Program,as all contaminant concentrations are below site target concentrations. The successful use of HRC: is dependent upon its effective injection over the affected zone in the shallow aquifer. The "top-down" injection methods employed in this project achieved even subsurface dist•ibulion of the HRC over a 15 it(4.6 1n) interval in a very low permeability aquifer. Other, less stringent, methods swill undoubtedly decrease required field time; however, poor treatment distribution can compromise the overall success of the injection project. Furthermore,removal of the source area contaminated soils (completed in 1998 by excavation under the dry cleaner's building) has also been important in the subsequent remedial success of this project. If allowed to remain in place, these highly contauninated source area soils provide a continuing source of contaminants leaching into the shallow aquifer. RE ri E4 RE- Bureau of Economic Geology,University of Texas. 1912. Geologic Atlas of Texar, Dallas Sheel. Puls, R.W. and M.J. Barcelona. 1996. Loin r1ou, (Minimal Dralydouvn) Grotmd-11�aler•Scaopling Procedures. EPA Publication EPA/540/S-95/504. Texas Water Development Board. 1994. Nle jar and Alinar Aquifers of Texas. Wiedemeier, T.H., J.T. Wilson, J.E. Hansen, and F.H. Chapelle. 1996. Technical Prolocol firr is'vahraling Meaured Allenualion of Chlorinuled Solvews in Groundivaler. Prepared fru•the Air Force Center for Environmental Excellence.