ARCHIVED REPORTS_XR0007301 - Laserfiche WebLink

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SCOPE OF WORK This work plan will cover determination of the horizontal and vertical limits of the contamination to the east of the fuel dispensing area and the vertical limits of the plume in the area of the dispensing islands rhe most likely expansion of the plume will be to the east under Wilson Way Soundings of the three existing monitoring wells have indicated that the hydraulic gradient vanes from northeast to southeast The City of Stockton will not allow soil borings and monitoring wells in the paved area of Wilson Way Soil Boring Location It is proposed that both shallow and deep eight inch soil borings with monitoring wells be placed three feet east of the east curb of Wilson Way The shallow boring(M W#4S)would be terminated ten feet into the top of the plume The deep borings(M W#4D)would terminate at the bottom of the plume These soil borings would be located within five feet of each other(see plot plan of soil borings attached) The upper extent of the plume in the area of the dispensing islands has been determined with previous soil borings It is proposed that one deep soil boring (MW#5D) be drilled to the extent of the contamination and a monitoring well be placed in that soil boring Sampling of Soil Boring Existing soil borings have shown contamination starting at twenty-five below the surface It is proposed that sampling begin at twenty feet below the surface for MW#5D and MW#4D and that MW#4S not be sampled Samples will be extracted with a split spoon sampler at five foot intervals to the bottom of the soil boring Soil Sample Transportation and Analysis Soil samples will be extracted with a metal liner that will be covered at the ends with a teflon sheet and secured with a standard plastic cap The cap will be secured with duct tap and the sample stored on ice for transport under a chain of custody to a state-certified laboratory The samples will be analyzed by EPA methods 8015, 8020, and 8260 and the findings presented in a standard engineering report Monitoring Well Construction Monitoring wells will be constructed with a two inch PVC casing The bottom ten feet of casing shall be slotted with 0 010 slots Filter sand for the slotted portions of monitoring wells shall be#2x#16 sand A two-foot plug of bentonite shall cover the filter section and cement grout will be pumped from the bentonite seal to the surface A well box with locking caps shall cover the monitoring wells (see monitoring well detail attached) Quarterly Monitoring Well Sampling All project monitoring wells will be sampled quarterly with a standard written engineering report of findings directed to the lead agency Receptor Survey A receptor survey should be conducted for the area within a 2000 foot radius of the site FUNDING This work plan is subject to both the City of Stockton permitting and funding from the UST Cleanup Fund The city must issue the required permits and the funding is subject to preapproval of the State of California UST Cleanup Fund before this work can be started 2