SITE INFORMATION AND CORRESPONDENCE

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Once impacted soils have been removed from the site, confirmation samples will be collected. If a confirmation result exceeds it corresponding cleanup goal, a determination will be made at that time in consultation with San Joaquin County Environmental Health Department(SJCEHD) and DTSC if a site-specific background concentration should be established or if additional remediation is needed. • Utilize sufficiently low analytical method reporting limits to determine if background concentrations naturally exceed relevant RSLs. As outlined in RAP Section 5.4.2, laboratory reporting limits will be sufficiently low to evaluate if COPC concentrations in the confirmation soil samples exceed their corresponding residential soil RSLs. (Note again that the cleanup goal for copper will be 3,100 mg/kg, not 31,000 mg/kg). • Evaluate the potential for the presence of polyaromatic hydrocarbons (PAIis) on the firing range floor and propose how these compounds will be addressed if present. The Interstate Technology Regulatory Council (ITRC) guidance document Characterization and Remediation of Soils at Closed Small Arms Firing Ranges indicates that PAHs are present in clay targets (which are used at shotgun ranges for trap and skeet shooting). The former police firing range layout is consistent with the example rifle/handgun firing range layout in the ITRC guidance document(Section 2.3). Accordingly, clay targets would typically not have been used and PAHs are not expected to be a COPC at the site. Additionally, the ITRC guidance document indicates that when present, clay targets did not exhibit the characteristics of toxicity even though they contained PAHs. The ITRC guidance further indicates that the primary COPCs at small arms firing ranges are usually metals and a study published in 2000 found no adverse health effects to human receptors due to PAHs. Accordingly, we do not propose to evaluate the potential presence of PAHs on the firing range floor. • Provide a history of land use of the area of interest prior to use as a firing range. The City of Manteca purchased this property in 1959 per deed 2341 OR 348 and the site is a small portion of a 94.5-acre parcel. The land at that time was used for agricultural purposes. The site was reportedly then used as a firing range from the early 1960's to 2009. • Provide a legal description of the area addressed by this investigation and corrective action of the former police firing range. A legal description does not currently exist.As reported in the RAP,the site occupies a portion of Assessor Parcel Number 241-310-44. Please contact us if you have questions regarding our responses to your comments. Sincerely, OCL G.� GEOCON�CJO/N/SJU/L�TANTS,INC. RICHARD , 4 W. DAY Ni • No. 5479 Richard Day, PG, Q06, CHG %p Exp.09-30-17 `Q Principal/Senior Geologist 19>. Q? FOR Cpt•1F0 Geocon Project No.E8857-02-01 -2- September 8,2016