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4.3 GROUNDWATER SAMPLING AND ANALYSIS 4.3.1 SAMPLING ACTIVITIES Groundwater elevations will be measured using an electronic water sounder. Prior to measuring groundwater at each well, the instrument will be decontaminated using a triple rinse process to ensure that no cross contamination between wells occurred. For each of the monitoring wells onsite, the groundwater level and the total depth of the well will be measured and recorded on well sampling forms. Groundwater will be sampled from each monitoring well based on the US EPA document titled Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures (EPA/540/S-95/504). This low-flow methodology will be used in order to prevent the following: mixing of the stagnant casing and fresh screen waters during insertion of sampling device; disturbance and re- suspension of settled solids at the bottom of the well when using high pumping rates and raising and lowering the pump and bailer; degassing from the bailer during sample handling and transfer; and introduction of the trace organics from the tubing and pump materials construction. A portable low-flow pump, with a pumping rate less than 0.5 Liters/minute, will be lowered into the monitoring well and placed approximately at the middle of the screened interval. To ensure that no cross contamination between wells occurs, the pump and any portable hosing will be decontaminated using a triple rinse process prior to purging each well. A low flow pump and flow-through cell will be used to monitor the stabilization of the field parameters. Using a water quality monitor (Hor(ba U-10 or equivalent) in combination with the flow-through cell device, the groundwater will be monitored in the field for the stability of pH, temperature, electrical conductance, and turbidity (in that order). These values will be recorded on well sampling logs. Well purging continues until stable values are obtained (+/-0.1 pH, +/-3% for conductivity, and +/- 10%for turbidity). Purged groundwater will be stored onsite in labeled, 55-gallon, Department of Transportation (DOT) approved drums. Once stability has been achieved, a water sample from each well will be pumped directly from the tubing into appropriate sample containers, supplied by the laboratory. In addition, trip blanks will be collected for quality assurance and quality control (QA/QC). After the samples are collected, they will be uniquely identified and placed into a cooler containing ice as described in the Sample Collection and Analysis Plan (Miller Brooks, 2007). The groundwater samples will be transported, by courier, to Calscience Environmental Laboratories (Calscience) in Garden Grove, California under chain of custody protocol. 4.3.2 LABORATORY ANALYSES A total of two samples will be collected from the newly installed off-site groundwater monitoring wells. All samples will be submitted to the laboratory for the following analyses: 7 M/LLER APAWOKS P:\707 Cove Contractors\WDR\Tech Report and WP 2008\Tech Report and WP_FINAL.doc