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8 <br /> or surged to settle the filter pack, and more sand will be added as necessary to return the level <br /> to a height of 2 feet above the top of the screen. A 2- to 3-foot-thick seal of bentonite pellets <br /> will be placed above the sand pack. The well will then be grouted with bentonite-cement slurry <br /> or neat cement, from the top of the bentonite seal to the surface. It will be completed below <br /> grade and protected with a water-tight locking cover. <br /> The County requires that groundwater samples collected from monitoring wells, which are <br /> located within 50 feet of a sanitary sewer line, be analyzed for coliform. If any of the proposed <br /> wells are located within 50 feet of a sanitary sewer line (according to Figure 2), the samples from <br /> this well will be sampled for this constituent. <br /> Property Owner Approval of Well Locations <br /> The owners of the properties where the five monitoring wells are proposed will be contacted <br /> and approval obtained prior to the well installation. The wells located in the public right-of-way <br /> are on City of Tracy property and a permit to install the wells will be obtained from the City of <br /> Tracy. Permission to install the wells located on private property will be obtained from the <br /> property owners and a license agreement between ARCO and the property owners will be <br /> obtained prior to commencing work. <br /> In the event that the City of Tracy denies permission to install monitoring wells on its <br /> property, ARCO will try to obtain approval to install each monitoring well on the private <br /> property closest to its presently proposed location. <br /> Monitoring Well Installation <br /> A maximum of five monitoring wells will be installed off site around ARCO Station 2093. <br /> The borings will be drilled to a depth of 15 feet below first groundwater. Groundwater is <br /> estimated to be approximately 10 feet below ground surface; therefore, the total depth of each <br /> monitoring well will be approximately 25 feet. After completion, each well will be developed. <br /> The procedures for monitoring well drilling and completion,well development, and soil sampling <br /> are described in Appendix A. <br /> After development, the groundwater in each well will be sampled and analyzed for total <br /> petroleum hydrocarbons; benzene, ethyibenzene, toluene, and xylenes; and 1,2-DCA. A <br /> description of the groundwater sampling procedures is included in Appendix A. <br /> Soil and Groundwater Disposal <br /> The soil generated during borehole drilling will be temporarily stored on site enveloped in <br /> plastic sheeting pending laboratory analysis of a composite sample (composite sample means: <br /> collection of samples from four discrete locations per 50 cubic yards of stockpile soil and then <br /> compositing in the laboratory for one analysis) collected from the stockpiled soil. The stockpiled <br /> soil will be disposed of in an approved waste disposal facility after laboratory results are <br /> received. The groundwater generated from the development of the wells will be temporarily <br />