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The SJCEHD reviewed WEGE's recent quarterly groundwater monitoring reports and requested the preparation of a workplan to further define the lateral and vertical extent of the soil and groundwater contamination plume in a letter dated August 24, 1999 That workplan is presented below in Tasks IN TASK I: PERMITS AND USA NOTIFICATION The installation of groundwater monitoring wells proposed in the following sections of this workplan will require the issue of well permits by the SJCEHD Two of the proposed wells are to be located within the City of Stockton public right-of-way and will require additional encroachment permits The proposed monitor well locations will be marked in white paint Underground Service Alert will then be notified at least 48 hours prior to any drilling activities in order to clear the marked locations for underground utilities TASK II: DRILLING AND COMPLETION OF GROUNDWATER MONITORING WELLS OVERVIEW OF THE SCHEDULING AND SITING OF MONITORING WELLS This workplan proposes the installation of four monitor wells for the purpose of establishing the vertical and lateral extent of soil and groundwater contamination at the site WEGE proposes to install these wells in two stages One initial well (MW4) will be installed at a location immediately east of the former UST to establish the vertical extent of contaminants in soil and groundwater below that already documented by the three existing monitor wells The historical minimum groundwater elevation at the site for the period of the UST operation was 72-77 feet bgs The three existing monitor wells that surround the former UST are screened to a maximum depth of 50 feet bgs Soil samples collected during the installation of those wells were not analyzed below a depth of 35 5 feet Monitor well MW4 will be drilled to a depth of 80 feet bgs at the location most likely to show the maximum vertical penetration of contaminants during the historical groundwater elevation minimum Soil samples will be collected at five-foot intervals to a depth of 50 feet bgs and a continuous core of soil samples will be collected from 50 to 80 feet bgs Hydropunch groundwater samples will be collected at 60, 70, and 80 feet bgs The soil and hydropunch samples will be screened in field with a PID and/or portable chromatograph and selected samples will be analyzed for concentrations of TPH-G, BTEX, MTBE, and total lead by a certified laboratory The field screening of soil and hydropunch groundwater samples will be used to establish a twenty-foot zone between 50 • and 80 feet bgs to be completed with machine slotted casing The certified laboratory results from the discrete soil and hydropunch samples will be used to identify and 3 ARC PUMP -WKPLN- 9128/99