Laserfiche WebLink
Report:Groundwater-quality Monitoring—January 20, 2003: 7500 West Eleventh Street, Tracy, CA, Page 16 <br /> ='`'' • An excavation that parallels the street would be opened in the northern <br /> shoulder of West Eleventh Street, having dimensions on the order of 100 <br /> ft. long by 10 ft. wide, the bottom of which would be some 15-20 ft. BGS. <br /> To provide necessary support for the adjacent highway, underground <br /> utility services and other infrastructure, the excavation may be shored and, <br /> where its bottom is below the groundwater table, it will be back-filled in a <br /> timely manner by 3-in. to 9-in. river-run rock or similar material <br /> containing no fines until that backfill forms a dry standing in the bottom of <br /> the pit. <br /> �= • Before the excavation is partially backfilled with rock all of the floating <br /> p Y � g <br /> product that flows into it, or migrates to, it from surrounding areas of the <br /> subsurface can be extracted by skimming the product from the water table <br /> into an 8,000-gallon capacity vacuum truck while the excavation remains <br /> open. Similarly, if appropriate, one or more volumes of groundwater equal <br /> to that of the submerged portion of the excavation that may be affected by <br /> high concentrations of analytes of concern can be pumped out and shipped <br /> for disposal at a permitted facility before the excavation is closed by <br /> completing the backfilling with engineered fill. <br /> 3.4.2 Preparation for Remediation Work <br /> The first step required to implement the recommended remediation is to investigate the <br /> willingness of public and private owners of land in the area around Monitoring Well <br /> MW-7 to allow temporary access so that the excavation work can proceed. Once that <br /> access is assured, SJC proposes to prepare both an engineering design and a cost <br /> `-' estimate. <br /> <} 3.5 Sample Down.-gradient Potable Water-supply Wells <br /> SJC also believes that to ensure that groundwater extracted from them is not affected by <br /> components of fuel hydrocarbons, samples should be recovered in a timely manner from <br /> the potable water supply wells that are in use in the area of, and close to, the plume of <br /> affected groundwater emanating fromn the 7500 West Eleventh Street property. The <br /> samples should be analyzed for the saine suite of analytes as is specified in Section 2.4 of <br /> this report. This recommendation was also made in Section 10.1 of our October 2002 <br /> report (The San Joaquin Company Inc. 2002c), in which the specific wells from which <br /> =: samples should be recovered and analyzed were specified. <br /> 3.6 Requirement for a Letter of Direction Before Work Can Proceed <br /> It is not possible for SJC to proceed with any of the engineering or physical remediation <br /> proposed above, until written notice of approval and a directive to perform the work is <br /> ` received by the Navarras from the SJEHD. Without such notice, the USTCF will not <br /> ; 1 <br /> sic <br /> L". <br />