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STANDARD OPERATING PROCEDURES Groundwater Level Measuring, Purging and Sampling Prior to groundwater sampling, static water level measurements are recorded for each well using a battery powered water level meter with a precision of plus of minus 0 01 foot All measurements are recorded as depth to water from the surveyed measuring point at the top of the casing Depth to water readings are converted to water level elevations referenced to the USGS mean sea level datum Each well is purged by removing a minimum of three to five well casing volumes of groundwater using either a pre-cleaned teflon bailer, a dedicated PVC bailer, a pre- cleaned disposable bailer, or a stainless steel pump During the purging of each well and prior to sampling,discharge water temperature, pH, and specific conductivity measurements are recorded and allowed to stabilize Stabilized measurements indicate that formation water has entered the well Purge water is stored in 55 gallon steel drums on site pending laboratory analysis results The groundwater sample is taken when the water level in the well recovers to 80% of its static level After purging, a groundwater sample is collected in accordance with California Regional Water Quality Control Board (RWQCB) procedures described in the Leaking Underground Fuel Tank (LLIFT) Field Manual, the Tri-Regional Board Staff Recommendations for Preliminary Evaluation and Investigation of Underground Tank Sites, and local regulatory guidelines i Groundwater samples are collected using a pre-cleaned teflon or stainless steel bailer equipped with a ball check valve The groundwater sample is first checked for the presence of free product in the sampling bailer Thickness of possible free product is measured using an electronic interface probe with a plus or minus 0 01 foot detection limit Sampling containers are filled directly from the bailer as soon after purging as possible Agitation is minimized during sample retrieval and transfer to containers to avoid possible sample aeration Groundwater samples are carefully decanted into laboratory prepared 40 milliliter volatile organic analysis (VOA) vials The VOA vials are filled completely, leaving no air bubbles after the teflon lined cap is screwed on Additional groundwater samples may be collected in one liter bottles All samples are labeled and stored in a portable ice chest with crushed ice to maintain a constant temperature of 4' Celsius A thermometer is kept in the ice chest to ensue that the proper temperature is maintained The samples are then delivered under chain of custody to a state certified hazardous materials testing laboratory Parker Environmental Services 4185 Rialto Court Pittsburg CA 94565-6116 Phone (510) 439-1024 Fax (510) 439-2566 I