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Woodward-Cly • <br /> Consultants <br /> Mr. James L. Tjosvold <br /> Project No. 90189N <br /> May 24, 1993 <br /> Page 3 <br /> closure quarterly groundwater monitoring be performed. W-C completed the post closure <br /> groundwater monitoring for the Field Avenue site. No additional activities have been <br /> conducted by W-C at the Field Avenue site since the completion of the post closure <br /> groundwater monitoring program since 1990. It is our understanding that the monitoring <br /> wells at the Field Avenue site have been inactive since the completion of the post closure <br /> groundwater monitoring. Since these wells are inactive, they should be decommissioned as <br /> required by the San Joaquin County Development Code 9-115 and the California Health and <br /> Safety Code, Section 24400. The decommissioning of the wells was discussed with Mr. <br /> Fernando Amador (DTSC) on April 13, 1993 and the activities to decommission these wells <br /> are to be included in this well decommissioning work plan. A total of 5 existing monitoring <br /> wells will be decommissioned at the Field Avenue site (Figure 3). <br /> 2.0 FIELD ACTIVITIES <br /> The following section describes the field activities to decommission 12 monitoring wells <br /> located at the Navy drive site and 5 monitoring wells located at the Field Avenue site. <br /> Table 1 summarizes total depth, screen interval, and diameter of the casing and borehole <br /> for each existing monitoring well. Figures 4 and 5 show typical subsurface geology and <br /> well construction for the monitoring wells at the Navy Drive and Field Avenue sites, <br /> respectively. The field activities described below were prepared in accordance with <br /> "Appropriate Techniques to Decommission (Abandon) Wells and Boreholes", Department <br /> of Toxic Substance Control-Region 1, California Environmental Protection Agency; "Water <br /> Well Standards: State of California", Department of Water Resources; and information <br /> provided by SJCPHS. The following sections describe decommissioning procedures for <br /> wells located in paved and unpaved areas. <br /> 2.1 EVALUATION OF WELLS <br /> Each monitoring well will be checked to determine if the well casing is free of obstructions <br /> (sediment or debris). This will be done by lowering a "well sounder" in to the well casing <br /> to determine the depth of the well. If the measured depth of the casing is close to the <br /> known depth of casing, the well will be designated free of obstruction. If a well has been <br /> determined to be obstructed, the obstruction (debris or sediment) will be removed. When <br /> 90189N/LIKA2/05-24-93 SAC <br /> vs <br />