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KAPREALIAN ENGINEERING, INC.�`'j K E 1 Consulting Engineers P. O. BOX 913 BENICIA, CA 94510 1415)676-9100 (707)746-6915 September 16, 1988 Work Plan-Monitoring Well Destruction Unocal Service Station #5098 5606 Pacific Avenue Stockton, California INTRODUCTION: This work plan describes the proposed destruction of two ground water monitoring wells, MW-1 and MW-7, at the referenced site. The work proposed herein is a necessary precursor to the excavation and aeration work that is outlined in Kaprealian Engineering, Inc. 's (KEI) proposal dated 2 September 1988 . Because the excavation of contaminated soil at the site will encompass the existing wells, KEI proposes to destroy the wells to prevent any additional contamination to the ground water. If required by the Regional Water Quality Control Board (RWQCB) and/or the San Joaquin Local Health District, the wells will be re-installed following refilling of the excavation. Details of the site history, location and site description are outlined in the 2 September work plan. FIELD ACTIVITIES KEI proposes to abandon wells MW-1 and MW-7 as shown on the attached Well Location Map. Exploration Geoservices, Inc. of San Jose (License 484288, C57) will be contracted to drill out the wells. Eight inch hollow stem continuous flight auger drilling equipment will be used. The wells will be drilled out to the total original depth and the PVC casings will be removed. With the augers in place in the boreholes, neat portland cement will be pumped through the augers to the bottom of the borehole. The augers will then be removed and the cement will be displaced into the borehole by use of the surface pump. The boreholes will be backfilled with cement to a depth of 40 feet below grade, which corresponds to the proposed depth of soil excavation at the site. The ground water table at the site is at a depth of approximately 42 to 50 feet below grade. MW-1 has a total depth of 60 feet. The precise depth of MW--7 is not known by KEI at this time but is at least 60 feet below grade. KEI will obtain the depth of MW-7 from the RWQCB by telephone on 19 September 1988.