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Quik Stop Station No 039 February 28,2000 <br /> Stockton,California Subsurface Site Assessment <br /> MonitorinLy Well Installation <br /> Borings MW-1, MW-2, and MW-3 were completed as 2-inch inside diameter (ID) <br /> groundwater monitoring wells Each of the groundwater monitoring wells was completed to <br /> a depth of approximately 60 feet bsg The lower portion of each monitoring well was <br /> constructed of 20 feet of 2-inch ID schedule 40 polyvinyl chloride (PVC) well screen with <br /> factory-machined 0 020-inch slots Blank 2-inch ID PVC casing was then extended from a <br /> depth of approximately 40 feet bsg to the ground surface in each well The annular space <br /> adjacent to the well screen portion of each well was backfilled with #3 Monterey sand to <br /> approximately two feet above the top of the screened interval A 2- to 3-foot thick bentonite <br /> seal was placed at the top of the sand pack in each of the wells, hydrated with approximately <br /> 5 gallons of fresh water, and a mix of neat cement/ bentonite grout was used to complete the <br /> annular seals to the surface The wells were completed with a flush-grade, water-tight well <br /> box at the surface The top of each well casing was secured with a locking watertight <br /> expansion cap and lock The monitoring well construction details are shown on the boring <br /> logs in Appendix C <br /> Monitoring Well Development and Sam lin <br /> On December 15, 1999, Horizon personnel were onsite to perform well development and <br /> groundwater sampling of groundwater monitoring wells MWA, MW-2, and MW-3 The <br /> wells were developed, purged, and sampled as described in Appendix B Depth to <br /> groundwater levels were taken before and after development, purging, and sampling of the <br /> wells, and recorded on Monitoring Well Data Sheets (Appendix D) Groundwater samples <br /> were contained in cooled storage for transport to the laboratory for the requested analyses <br /> Wellhead Elevation Survey <br /> On December 29, 1999, the wellheads for the newly installed groundwater monitoring wells <br /> MW-1, MW-2, and MW-3 were surveyed relative to an arbitrary datum by Horizon <br /> personnel The calculated results of the wellhead survey are included in Appendix E, and <br /> with the groundwater data to Table 2 Water-level data collected on December 15, 1999 <br /> were used to construct the Groundwater Contour Map (Figure 2) The groundwater <br /> 7039-12 rpt 5 HORIZON ENVIRONMENTAL INC <br />