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GEVVON <br /> CONSULTANTS, INC. <br /> G E O T E C H N I C A L ■ ENVIRONMENTAL ■ MATERIALS <br /> Geocon Project No. E8857-02-02 <br /> August 25, 2017 <br /> Ms. Johanna Ferriera <br /> City of Manteca <br /> 1001 W. Center Street <br /> Manteca, California 95337 <br /> Subject: FORMER POLICE FIRING RANGE <br /> DOCUMENTATION OF OBSERVATIONS AND CONFIRMATION SAMPLING <br /> Dear Ms. Ferriera: <br /> Geocon is submitting this letter report to document our observations during the remediation of the <br /> former police firing range (Site) in Manteca, California. This report also summarizes confirmation <br /> sampling performed by Geocon outside of the primary excavation area, which was performed to <br /> satisfy the requirements of San Joaquin County Environmental Health Department (SJCEHD). <br /> Confirmation sample results for areas within the primary excavation are documented separately in the <br /> Clean Closure Report, prepared by Pacific Edge Engineering. The site location is depicted on the <br /> Vicinity Map, Figure 1. <br /> On February 22, 2017, Geocon staked the approximate limits of lead-impacted soil anticipated to be <br /> excavated and disposed of as Federal Resource Conservation and Recovery Act (RCRA) hazardous <br /> waste and as California non-RCRA hazardous waste based on the October 2015 Site Investigation <br /> Report(SIR) findings. Based on the SIR findings, soil with estimated lead concentrations between 50 <br /> milligrams per kilogram (mg/kg) and 135 mg/kg was to be managed and disposed of as a California <br /> non-RCRA hazardous waste and soil with estimated lead concentrations greater than 135 mg/kg was to <br /> be managed and disposed of as a Federal RCRA hazardous waste. <br /> Between March 6 and June 8, 2017, on behalf of the City of Manteca, Geocon observed the excavation <br /> and loading of lead-impacted soil performed by Innovative Construction Solutions (ICS). Geocon <br /> assisted with the segregation of soil to be managed and disposed of as RCRA and non-RCRA <br /> hazardous wastes using a hand-held x-ray fluorescence (XRF) device to estimate lead concentrations. <br /> Following initial excavation in March 2017, at the direction of Mr. Michael Kith with SJCEHD, <br /> Geocon collected confirmation samples on March 16 and 17, 2017, from the perimeter surrounding the <br /> excavation (samples P1 to P18) at approximate 25-foot intervals, from the remaining general site areas <br /> (samples G1 to G13) on a 50-foot by 50-foot grid, and at three locations selected by Mr. Kith from <br /> within the vegetation grub pile (samples Grub to Grub3). The location of each sample was recorded <br /> using a hand-held differential global positioning system (GPS). The sample coordinates are <br /> summarized in Table 1. Confirmation sample locations are shown on the Site Plan, Figure 2. <br /> 6671 Brisa Street ■ Livermore,CA 94550-2505 0 Telephone 925.371-5900 ■ Fax 925.371.5915 <br />