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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/WORKPLAN PROPOSAL RMC Pacific Materials (RMC) is submitting the following remedial investigation/workplan based on a July 21, 2003 meeting between San Joaquin County Public Health Services and RMC personnel at the RMC Kerlinger Aggregate Plant located at 30350 South Tracy Boulevard, Tracy, California(Figure 1). A verbal agreement was made on that date between the two parties delineating RMC's responsibilities for sampling and laboratory analysis during the initial two quarters of 2003. The agreement is as follows: Collect eftquarters of groundwater quality samples from the three monitoring wells shown on Figure 2. Analyze the samples taken during all eight sampling events for TPH-diesel (EPA Method 8015M). In addition,the samples taken during, at least, the first two quarters will be analyzed for benzene, toluene, ethylbenzene and xylene (BTEX). If, during the first two sampling events, it is determined that volatile-range ? petroleum hydrocarbons are not present in the groundwater samples then RMC will only be required to have all subsequent groundwater samples analyzed for TPH-diesel. At the end of that period the results of all analyses from the eight quarterly reports will reviewed by Health Services to determine if contamination to groundwater has occurred. Also at that time, RMC will contact Health Services to negotiate a remediation investigation/workplan proposal to further define the extent of contaminated soils at the site. 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 into laboratory-supplied containers directly from the pump discharge sampling 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