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y 22 November 1996 AGE-NC Project No 95-0130 Page 4 of 4 • Generally, concentrations of dissolved petroleum hydrocarbon constituents increased in four of five on-going monitoring points at the site The overall increase of detectable hydrocarbon concentrations, especially in several down-gradient monitoring wells, is suggestive of an unstable dissolved hydrocarbon plume r42 RECOMMENDATIONS Based on the probability of an o$-site source of hydrocarbons, further delineation of the plume should be performed in the up-gradient direction We recommend the installation of two additional monitoring wells on or adjacent to the former Wells Fargo Bank property A Remedial Action Work Plan is to be submitted to the PHS-EHD for a soil vapor extraction system in the area of the highest observed hydrocarbon concentrations Upon regulatory approval, installation of the remediation system should commence Vapor extraction well VW-1C should be surveyed and tied into the existing well casing elevation database, and should be utilized as an additional point for monitoring ground water elevations until initiation of the remedial action curtails such usage of the«ell The next quarterly monitoring and sampling is scheduled for January 1997 50 LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities The findings were based upon analytical results provided by an independent laboratory Evaluations of the geologic/hydrogeologic conditions at the site for the purpose of this investigation were made from a limited number of available data points (i e borings, monitoring wells), and subsurface conditions may vary away from these data points No other warranty, expressed or implied, is made as to the professional recommendations contained in this report