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Ms. Diane Hinson -2- 2 June 1989 <br /> Stat regulations require that during tank removals a soil sample is to be <br /> col ected beneath the product pipelines for every 20 lineal feet of pipeline. <br /> e soil samples are to be collected within the first two feet of native <br /> s i1 eath the pipeline trench. These s allow borings could be done using a <br /> and auger. <br /> As requested in our 17 March 1989 letter t Mr Brophy, quarterly ground water <br /> monitoring should be initiated. Water sam les are to be analyzed for benzene, <br /> toluene, xylene and ethylbenzene (BTX&E) aid total petroleum hydrocarbons <br /> (TPH) as gasoline and diesel . Quarterly monitoring reports should be <br /> submitted by mid-April , July, October, and January for the previous calendar <br /> quarter. <br /> The Tri-Regional Recommendations specify that a monitoring well be installed <br /> within ten feet of the tank pit in the verified downgradient direction. This <br /> monitoring well should be installed, but we recommend that ground water levels <br /> be measured and gradient direction calculated once again prior to selecting <br /> the installation location. <br /> In summary, we recommend the following worl be conducted at this site: <br /> 1. Soil borings should be drilled north and east of the tank pit to <br /> determine the extent of soil contamination. Ideally, the western extent <br /> should also be determined, but the proximity of the building makes it <br /> impractical . <br /> l <br /> D2 Soil samples are to be collected for every 20 lineal feet of product <br /> pipeline and beneath the pump islands . If the pipelines have not been <br /> removed, they are to be removed at t is time. <br /> 3. Quarterly ground water monitoring of water levels and BTX&E and TPH as <br /> gasoline and diesel should be initiated. <br /> 4. A monitoring well is to be installed within ten feet of the tank pit in <br /> the verified downgradient direction. <br /> It must also be noted that the extent of t e ground water contamination may <br /> need to be further defined. The need for further definition of the plume will <br /> be based on the quarterly monitoring results. <br /> If you have any questions, please call me at (916) 361-5725. <br /> EDWARD W. J MES <br /> Engineering Geologist <br /> EWJ:ewj <br />