ARCHIVED REPORTS XR0009904 - Laserfiche WebLink

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Corrective Action Plan Page 39 The boring logs and construction details of each replacement well will be filed with the California Department of Water Resources POST-REMEDIATION GROUNDWATER-QUALITY MONITORING G When the site has been restored following completion of the active phases of remediation, the following program of groundwater-quality monitoring will be initiated Base-Line Data To establish base-line data for long-term groundwater-quality monitoring, the depths to groundwater will be measured in, and samples will be recovered from, all, then existing, monitoring wells installed for the 152 East 1 I th Street site (i e Wells NAV 2, NAV 4, NAV 5, NAV 6, NAV 7, NAV 8, NAV 9 and NAV 10) Monitoring to Check the Progress of Remediation The progress of remediation will be monitored by analysis of samples recovered from each of the wells located within the plume of contamination on the 152 East Street site These will be wells NAV 4, NAV 9 and NAV 10 Monitoring to Confirm the Areal Limits of Contamination To confirm that the areal extent of thelume of contaminated p o taminated groundwater and the rate of its migration does not unexpectedly change, and to check for the arrival of any hydrocarbon fuel contamination migrating from up-gradient or co-gradient locations, samples will be recovered from monitoring wells NAV 2, NAV 5, NAV b, NAV 7 and NAV 8 These wells are located around the perimeter of the plume and analyses of samples recovered from them have consistently shown them to be free of detectable concentrations of contaminants Consistent with the program established by the Groijndwatej[ Sampling Plan - 152 Fast I Ith._Street, Tracy, Califoma (Ref 10) that has been approved by the S7CPHS, sampling rounds will be performed twice per year - once during the annual wet season (February) and once during the dry season (September) ' Determination of Groundwater Elevations Prior to each round of groundwater sampling, the depth from the top of the casing to the water table will be measured in all monitoring wells installed for the 152 East I 1 th Street site These data will be used to compute the groundwater table elevations relative to the local datum that has been established on the top of the casing of Well ULT 7, which was assigned a nominal elevation of 50 00 ft The computed groundwater-table elevations will be used to produce contour maps of the groundwater table and determine the direction 1 and magnitude of the groundwater-flow gradient r