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PROPOSED WORK PLAN FOR INSTALLATION OF VADOSE ZONE MONITORING WELLS AT TRACY, CALIFORNIA SCS Engineers (SCS) on behalf of City of Tracy (City) proposes to install 3 vadose zone monitoring wells at the City owned site (Assessor No. 253-11-22) near Tracy Municipal Airport where the excavated soil from Schulte Road extension will be bioremediated. These proposed wells will be placed to monitor the vadose zone underlying the site for any possible contamination during bioremediation treatment process. The locations of three proposed monitoring wells are shown in Figure 1. Wells are expected to be approximately 20 feet in depth. A detailed boring log will be recorded by the Field Geologist during the drilling and will denote sample locations, lithology of sediments encountered, depth to groundwater, and well construction details. The wells will be installed using 1" Schedule 40 PVC Casing, 0.01 inch slotted sections in the bottom 15' and blank sections up to ground surface. Lonestar #3 sand will be placed in the annular space to two feet above the perforated casing. A one to two foot thick bentonite seal will be put above the sand, and the wells will then be grouted to ground level. A locking well cover will be cemented in place over the wells head at least one inch above the surrounding surface. A schematic showing a typical monitoring well construction is present in Figure 2. Soil samples will be acquired at five foot intervals. All sampling containers will be labeled immediately after the samples are collected. Samples will be kept in cold packs until received by the laboratory. At the time of sampling, each sample will be logged on a Chain-of-Custody form which will accompany the sample to the laboratory. All samples will be tested by EPA Protocol 8015 for Total Petroleum Hydrocarbons, 8020 for Benzene, Toluene, Ethylbenzene and Xylene (BTEX) and 418.1 for total oil and grease. Once the field work and chemical testing is completed, a report will be prepared by SCS which will include a summary of all activities completed. Boring logs, well construction diagrams, would be placed as an appendix. The certified laboratory test results will be included. The wells will be tested for organic vapors using the following procedure. First a calibrated organic vapor analyzer (OVA) and photo ionization detector (PID) will be connected to lab cock. The lab cock valve will be opened and after one minute, the maximum and steady value of the vapors, if any, will be recorded. After recording the values, the OVA will be disconnected, and lab cock will be closed. Level D safety protection consisting of steel-toed boots, gloves and hard hats, will be provided. Respirators filled with organic vapor cartridges will also be kept on hand in case they are needed. The drill cuttings will be kept on site, sandwiched between two layers of polyvinyl cover pending receipt of sample analyses results. There upon, proper disposal of the cuttings will take place. Wells will be monitored monthly for the presence of any organic vapors due to the treatment process.