ARCHIVED REPORTS XR0008270 - Laserfiche WebLink

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Problem Assessment Report for Sail and Groundwater Contamination Corrigan Property (Project No W0541 00) Analytical results of groundwater samples collected from the saes monitoring wells detected petroleum hydrocarbon constituents in well MW2 only The groundwater flow was determined to be in the southern direction. Field activities performed during the initial investigation are discussed in detail in WaterWork's Preliminary Report, dated June 17, 1991 At the request of San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD), RESNA Industries, Inc (RESNA) began quarterly monitoring and sampling of site monitoring wells MW1, MW2, and MW3 on January 8, 1992 Analyses of collected water samples detected only xylene at 0 b ppb in well MW2 on July 9, 1992. To date, no other analytes have been detected in the site monitoring wells Groundwater flow was determined to be consistently in the southern direction During a file review of the site's historical groundwater data, errors were discovered in the calculations used to determine the monitoring wellhead elevations A resurvey of relative wellhead elevations conducted on December 9, 1992 verified that the original survey data was accurate, however the calculated wellhead elevations were incorrect. Using the original survey data, wellhead and groundwater elevations have been recalculated. The corrected groundwater elevation data are shown on Table 3 Using a kriging program, groundwater gradient maps were recreated for all past monitoring episodes and are included as Figures 3 through 8. These figures depict a consistently east- northeast groundwater flow direction This is congruent with the regional groundwater gradient direction which flows north-easterly toward a groundwater depression located east of Stockton (San Joaquin County Flood Control and Water Conservation District, Spring 1992) soPAR -0343 FNL 2