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,%go, sow, <br /> I.d <br /> SMTH SITE SAFETY PLAN <br /> 4.0 <br /> FACHJTY BACKGROUND <br /> In August 1986, SEMCO general engineers of Modesto, CA removed from the site three <br /> gasoline underground storage tanks (USTs) (two 2,000 gallon, and one 3,000 gallon), and <br /> one 350 gallon waste oil UST. Analysis of groundwater samples collected from the <br /> excavation indicated that elevated concentrations of petroleum hydrocarbons were present <br /> in groundwater in the UST excavations. <br /> Ime <br /> WORK PLAN <br /> V <br /> Task One: Three soil borings will be advanced to depths of approximately 30 feet using <br /> 10-inch O.D. hollow stem augers. Drilling will be conducted by a State- <br /> licensed (C57) drilling company. A field geologist will be present to log all <br /> drill cuttings and soil samples. Descriptions of soil types encountered, sample <br /> collection intervals, and well construction details will be recorded on <br /> boring/well logs and included in the PSA report. Soil samples will be <br /> collected at five foot intervals and selected samples will be submitted for <br /> laboratory analysis of TPHg and BTEX. <br /> All drill cuttings will be placed on and covered with plastic and stored on-site <br /> pending laboratory results. The borings will be completed as groundwater <br /> monitoring wells. The monitoring wells will be constructed of flinch inside <br /> diameter PVC well screen and casing. <br /> V <br /> Task Two: SMTH personnel will measure the depth to water in the wells and will <br /> develop the new wells using surge and bail techniques until the produced <br /> water is relatively sediment free. Prior to the collection of groundwater <br /> samples, a minimum of three well volumes (casing and sandpack) will be <br /> purged. Temperature, pH, water elevation, and electric conductivity will be <br /> i- measured and allowed to stabilize. Water samples will be collected using <br /> disposable bailers, one dedicated to each well. Groundwater samples <br /> collected from all monitoring wells will be submitted using chain-of-custody <br /> record to a State-certified laboratory for analysis of TPHg and BTEX using <br /> EPA methods 5030/8015/8020, respectively. Purge water will be stored in 55- <br /> gallon drums approved for hazardous liquid storage pending laboratory <br /> analysis. The top of the new wellheads will be surveyed and tied together. <br /> V <br /> v PACE 2 <br /> v <br />