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3.0 PROPOSED WORKPLAN <br /> To prevent the contaminated soils within the former tank pit <br /> from presenting a continued threat to groundwater, WaterWork <br /> will remove and remediate contaminated soils. <br /> To assess the lateral and vertical extent of soil and <br /> groundwater contamination at the project site, WaterWork <br /> .� proposes to drill and sample three soil borings around the <br /> , < tank excavation which will be converted to groundwater <br /> monitoring wells. The proposed boring/well locations are <br /> , plotted on Figure 2. The soil borings should be adequate to <br /> define the lateral and vertical extent of soil contamination <br /> at the project site. The three monitoring wells should <br /> adequately define the lateral extent of groundwater <br /> contamination at the project site. One of the proposed <br /> monitoring wells will be located up-gradient of the <br /> excavation. Should it be determined that groundwater <br /> e contamination extends beyond the property lines of the <br /> i , project site, additional monitoring wells may be proposed in <br /> a future assessment plan. <br /> 3.1 Workscope/methodology <br /> The following scope of work is proposed: <br /> : 1. The tank pit will be re-excavated to remove any <br /> potential continuing source of groundwater degradation. <br /> Soils within the saturated zone will not be removed. <br /> t Excavated soils will be screened for the presence of <br /> gasoline hydrocarbons using a photoionization detector <br /> (PFD) calibrat.,:d to an isobutylene standard. Four wall <br /> '.Y confirmatim samples will be collected in accordance <br /> with Waive c::k Protocols (Appendix 11). Soil samples <br /> will be sr,_jP.yxed for BTEX and TPHG by EPA and DHS <br /> 6 ` methodolcgls,as, as appropriate. <br /> 2. Excavated soils will be stockpiled on-site, placed on <br /> and covered with 6 mil plastic sheeting. Contaminated <br /> soil will be aerated on-site under permit from the San <br /> Joaquin County Aix' Pollution control District (air <br /> board). Composite samples will be collected from the <br /> excavated material as required by the air board for <br /> processing of the aeration permit. Treated soils will r� <br /> be backfilled into the excavation. Successful treatment <br /> i .y. will be verified by sampling in accordance with County <br /> k� regulations. <br /> 3. Three soil borings will be drilled to depths of 25 feet <br /> below grade or 15 feet below the depth where standing <br /> water is first encountered in the boreholes. The <br /> - <br /> borings will subsequently be converted to groundwater <br /> monitoring wells. <br /> r <br /> i <br /> 3 <br /> r <br /> $€f <br />