Laserfiche WebLink
. APR-05-99 14:15 From MODWARD CLYDE + T-122 P 06/0T Job-942 <br /> '%� 1�0-/ <br /> A State-certified mobile laboratory owned and operated by On Site will analyze collected <br /> samples for TPH and volatile organic compounds (VOCs) in accordance with EPA Methods <br /> 5015 modified and 8020, respectively. Replicate samples may be submitted to a stationary <br /> laboratory for VOC concentration analyses using EPA Method 8260. In addition, it is proposed <br /> that up to four groundwater samples from Shop 10's groundwater monitoring wells be analyzed <br /> for sulfate and nitrate (indicators of the biodegradation potential of the subsurface). Field <br /> measurements will be collected for pH, conductivity, temperature and dissolved oxygen levels in <br /> groundwater. <br /> Task 3-Estimation of Hydraulic Conductivity <br /> To estimate the hydraulic conductivity beneath Shop 10, Slug tests in up to two monitoring wells <br /> located in the vicinity of the fomter underground storage tank(UST)arta will be conducted. The <br /> slug test will be performed by measuring the instantaneous response within a well after <br /> introducing a mandrel (slug) of specified weight attd volume. Water elevation data will be <br /> collected using a pressure transducer and data loggers over specified time intervals until static <br /> conditions are achieved. After static conditions are achieved, water elevation data will be <br /> collected upon removal of the mandrel from the respective well. Graphs depicting the change in <br /> water level with time will theft be used to estimate the hydraulic conductivity for the water- <br /> bearing zone screened in each respective monitoring well. The hydraulic conductivity estimates <br /> will be used to estimate the groundwater velocity. <br /> Tack 4 Estimation of Petroleum Hydrocarbon Mass in Groundwater and Soil <br /> As part of the data evaluation, the extent of petroleum hydrocarbons in groundwater (based on <br /> current groundwater monitoring data from the 1"quarter 1999 groundwater monitoring event and <br /> the discrete vertical groundwater sampling) will be depicted horizontally and vertically (if <br /> Applicable). In addition. the most recent soil analytical data, will be depicted horizontally and <br /> vertically on contaminant isoconcentration maps to evaluate the extent of petroleum <br /> hydrocarbons in soil. Previous investigation data and current investigation will be reviewed to <br /> estimate the mass of petroleum hydrocarbons in subsurface soil and groundwater. Geologic cross <br /> sections using stratigraphic data from previous investigations will be developed. The mass of <br /> total petroleum hydrocarbons (TpH - ,gasoline and diesel range) and benzene in groundwater and <br /> soil will be estimated. <br /> C_\ea1kransWkin/wr pin2.doc <br />