ARCHIVED REPORTS XR0000301 - Laserfiche WebLink

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Ile 2.0 PROPOSED SITE ACTIVITIES The proposed site activities will consist of constructing a new groundwater monitoring well (designated MW-4) downgradient from the former gasoline tank location, and sampling and analysis of the groundwater in the newly installed well for gasoline related constituents. Sampling of MW-4 will be conducted as part of the quarterly groundwater monitoring program currently in progress on the site. 2.1 General Requirements This work plan has been developed to conform to the Tri-Regional Recommendations and is ' structured to address the concern of the San Joaquin County EHD All work described below will be completed under the direction of a California Registered Geologist and all analytical ' work will be conducted by an analytical laboratory certified by the State of California 2.2 Well Location tThe new monitoring well will be located in a downgradient position with respect to the former gasoline tank and the other monitoring wells on the site as shown on Figure 2 For the purpose ' of this work plan, the downgradient position was determined to be toward the north-northeast based on groundwater gradient data for March 18, 1987 collected by another consultant Because there is at present no way to confirm this gradient data, it is possible that the previously reported gradient direction determined from data now five years old does not reflect current conditions Prior to constructing the new monitoring well, an additional effort will be made to ' verify the gradient direction onsite so that the new well will satisfy its intended purpose This effort will consist of rechecking the existing wells to determine if recent rams have raised the site water table enough to determine the current gradient In addition, other information sources such as published maps, etc. will be checked for current area-wide gradient data. If the gradient is found to be significantly different from that stated above, the new well location will be adjusted accordingly and the EHD will be advised If, due to the recent rains, all the wells ' onsite are found to contain water, then the need for a new well will be reevaluated ' 2.3 Monitoring Well Installation The monitoring well will be constructed by hollow stem auger drilling techniques with a 4-inch ' diameter PVC casing and a 20 foot screened section. It is estimated that the well total depth will be approximately 70 feet The screen will be located to set the top of screen at least three feet above the saturated zone A sand pack will be emplaced throughout the screened interval and ' will extend at least two feet above the top of the screen A bentonite seal will be placed above the sand and the annular space will be grouted above the seal to the surface with a five percent bentonite/cement grout The monitoring well will be completed in a flush mount chnstie box ' equipped with a locking cap. 0 ' K 3 �,M PI'S\SICMADWK PLN