Laserfiche WebLink
1 <br /> The possibility remains that the former tank site is the source of some or all of the hydrocarbons <br /> found in the groundwater But in light of the compound concentrations, distribution and <br /> groundwater flow directions, there is a possibility that other sources may be contributing to the <br /> presence of some or all of the hydrocarbons beneath the site <br /> 6.0 RECOMAM"ATIONS <br /> In view of the results of this investigation, WESTON recommends that a quarterly groundwater <br />' monitoring program be conducted for a period of one year (four quarterly monitoring events) <br /> to try to determine the predominant groundwater flow direction for the site and to continue to <br /> track the hydrocarbon compound distribution in the groundwater If after the first monitoring <br /> event is completed the predominant flow direction is not clear, an additional investigation of the <br /> tidal influence on the gradient should be implemented in order to separate out the tidal effects <br /> from the predominant flow direction <br /> The quarterly monitoring program would consist of collection of groundwater elevation <br /> measurements and groundwater samples from each well Because no significant TPH-D, EDB <br />' or total lead concentrations were found in any of the wells, WESTON recommends analyzing <br /> the quarterly samples only for BTEX and TPH-G <br /> t Results of each monitoring event would be presented in a quarterly monitoring report which <br /> would include a summary table of analytical results, a groundwater elevation contour map, a <br /> field report of sample collection activities and a complete report of analytical results <br /> WESTON also recommends a review of past practices in the vicinity of the site to determine the <br /> P P Y <br /> likelihood of other hydrocarbon sources in the area Such sources might include other <br /> underground fuel storage facilities such as gas stations, bus refueling facilities, bulk storage <br /> facilities, etc <br />' 7.0 REFERENCES <br />' Freeze and Cherry, 1979, Groundwater, Prentice Hall, 604 p <br /> San Joaquin County Flood Control District, Semi-Annual Groundwater Report, Fall, 1991 <br />' WESTON, 1989, Problem Assessment Report (PAR) Underground Fuel Storage Tank Site <br /> Investigation, February 20, 1989 <br /> 1 WESTON, 1989, Work Plan for Phase II Groundwater Investigation Human Services Building <br /> Site <br /> 1 <br /> RffSMc wa 2.2 06MZV2 <br /> 1 <br />