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12/06/00 WED 17_58 FAX 916 3820802 DAMES & MOORE SAC • 2008 DDJC-Tracy OU 1 Groundwater Treatment for Pesticides,Pump Test Work Plan 1.0 INTRODUCTION abandonment of the wells at the completion of the aquifer test. 1.1 The purpose of this document is to describe the specific field activities to be performed in 2.1 Temporary Piezometer support of remediation efforts at Defense Installation Distribution Depot San Joaquin,Califomia (DDJC)-Tracy, California. The work to be 2.1.1 Thirteen temporary observation performed under this effort will include piezometer wells(OW-WTO1 through temporary observation piezometer installation OW-WT13,see Figures 3 and 4)will be and aquifer testing at existing monitoring and installed and developed according to the general extraction wells, procedures described in the Comprehensive Field Work Plan as modified by this work plan. 1.2 This project-specific work plan is an All temporary observation piezometer wells will addendum to the Comprehensive Field Work be completed in the Above Upper Horizon zone Plan(Radian International,2000)for all field ranging from approximately 20 to 30 feet below activities at DDJC-Sharp and DDJC-Tracy. ground surface(bgs). General procedures, specifications,and requirements for the work described in this 2.1.2 The observation piezometers will be project-specific work plan are presented in the placed at distances of 10,25,50, 100, 150 and Comprehensive Field Work Plan and will be 200 feet from the tested well for LM 174AU and performed as set forth in that plan. as shown for EW 040AU. They will he aligned parallel to the east-west access road to the 2.0 FIELD WORK SUMMARY immediate north of EW 040AU and LM 174AU. This alignment was selected to evaluate the 2.0.1 The work to be performed during this field potential capture zones for each well at the test- effort at DDJC-Tracy is scheduled to begin in pumping rate. Final placement and distances November 2000 and includes the following: will be determined by field conditions. • Installation of 13 temporary observation 2.1.3 Borings for the observation piezometers piezometers; will be created using direct push techniques similar to those used for cone penetrometer • Aquifer testing of existing wells EW 040AU testing(CPT). This involves pushing a 2-to and LM 174AU(future EW 045AU); 3-inch diameter casing with a drive tip into the ground to the desired depth. This depth will • Surveying locations of the temporary initially be estimated based upon the current observation piezometers;and water level in existing nearby wells and the distance firm the extraction well. When the • Abandonment of the temporary observation boring has reached the desired depth,the casing piezometer wells. will be pulled partially back to permit groundwater to enter. Once the water level 2.0.2 The location of this work is shown in within the casing has stabilized,the depth to Figure 1.The proposed temporary observation water will be measured and the final screen piezometer locations are depicted on Figures 2 requirements for the observation piezometer will through 4. This phase of field work will begin be determined, with the installation of the temporary observation piezometer wells. Once installed, 2.1.4 The blank casing for the observation these observation piezometers will be given an piezometers will be 1 %cinch diameter flush- "OW'prefix prefix designation with a number and thread PVC pipe. The casing will be free of letter in accordance with the current designation solvents, oils,grease, paint and dirt and will be system at DDJC-Tracy' Observation piezometer certified clean from the factory or steam cleaned well locations will be surveyed prior to the on site prior to installation. The casing will not OU-1 Pump Tm VIP 1 November 2000