SITE INFORMATION AND CORRESPONDENCE_CASE 2

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..r INTENT OF THIS PROPOSED SAMPLING PLAN This proposed sampling plan is intended to determine if the local groundwater at the referenced site has been adversely affected by surface petroleum hydrocarbon contamination. REMEDIAL INVESTIGATION/SAMPLING PLAN PROPOSAL RMC Pacific Materials (RMC) is submitting the following revised remedial investigation/ sampling plan for our Kerlinger Aggregate Plant (Site #1737) located at 30350 South Tracy Boulevard, Tracy, California(Figure 1). This submittal is to comply with comments presented in the letter from San Joaquin County Public Health Services dated November 10, 2003. A summary of the main points of the sampling plan are as follows: Collect at least eight quarters of groundwater quality samples from the three monitoring wells shown on Figure 2. Submit the samples to a state certified laboratory for analysis for TPH-diesel (EPA Method 8015M and benzene, toluene, ethylbenzene and xylene (BTEX). If after one full year of sampling all analytical results are less than the detection limit for the analytes in question, RMC may request a reduction in the requirements set fourth in this sampling plan. The first sampling event that conforms to the requirements of this revised plan was undertaken on July 16, 2003. GROUNDWATER SAMPLE COLLECTION Three groundwater-monitoring wells are located at the above-referenced site. Sampling of these wells will be undertaken on a quarterly basis for eight consecutive quarters. All sampling events will begin by taking depth-to-water measurements at each of the wells with an electronic water tape. The depth-to-water measurements will be recorded on water quality sample collection log sheets. The measurements will be used to calculate the well casing volumes and the proper amount of water to be purged from each well. The measurements will also be used to monitor changes in the groundwater flow gradient. Each well will then be purged of no less than three casing volumes of water in order to ensure sampling the native groundwater. Purging will be carried out using the dedicated bladder pump (QED model P 1101 M) that has been installed in each well. All purged water volumes will be recorded on the sample collection log sheet along with periodic pH,temperature and conductivity measurements. Sampling will begin after three casing volumes have been removed from the well and the periodic measurements taken during the purging process have stabilized. Groundwater samples will be collected directly into laboratory-supplied containers from the pump discharge tube. Sample volumes will consist of two one-liter amber glass containers and a pair of 40-m1 VOA vials. Each sample container will be filled completely, capped and then checked for trapped air by inversion and tapping. If an air bubble is observed in a vial, that vial will be reopened and topped off with additional water until no bubbles exist when the container is inverted. All samples will be properly labeled and then placed into a chilled cooler for transportation to a State certified laboratory for analysis. Strict chain-of-custody protocol will be followed during all phases of sample handling.