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F93808.01 <br />Page 4 <br />9505 North West Lane, Stockton, California <br />March 25, 2005 <br />CONCLUSIONS <br />No impacts of cyanide, chromium VI, SVOCs, PCBs, organochlorine pesticides, or <br />organophospherous pesticides were detected above laboratory reporting limits in the surface samples <br />or the sub-surface samples analyzed from the imported fill material. Total petroleum hydrocarbons <br />and the PAHs chrysene and pyrene were detected just at or above method detection limits in several <br />of the samples analyzed from the imported fill material. <br />Concentrations of metals detected in the imported fill material were similar to background with the <br />exception of arsenic and chromium which were detected at concentrations of 4.1 mg/kg and 67 <br />mg/kg respectively in the sample collected from SB-3 at 3-3.5 feet bsg and at 4.2 mg/kg and 66 <br />mg/kg respectively in the sample collected from SB-4 at 5.5-6 feet bsg. Based on the California <br />Code of Regulations, Title 22, Chapter 11, Article 3 the concentrations of arsenic and chromium <br />were below their respective Total Threshold Limit Concentration (TTLC) and are therefore <br />considered non-hazardous. In addition, no hexavalent chromium (chromium VI) was detected above <br />laboratory reporting limits in these two samples or in any of the samples analyzed. The <br />concentrations of chromium detected in these two samples were below the Preliminary Remediation <br />Goals (PRGs) for residential soils established for chromium of 100,000 mg/kg. This excludes <br />chromium VI, which was not detected in any of the samples analyzed. Nevertheless the <br />concentrations of chromium at these two locations exceeded ten times the Soluble Threshold Limit <br />Concentration (STLC) for chromium of 50 mg/L and should therefore be analyzed using a waste <br />extraction test (WET) to further determine the soluble concentrations of chromium concentration at <br />these two locations. <br />LIMITATIONS <br />The work is intended to be an interactive process. Additional work may be required to more fully <br />characterize the condition of the imported fill material. The purpose of a geologic/hydrogeologic <br />study is to reasonably characterize existing site conditions based on the geology/hydrogeology of the <br />area. In performing such a study, it is understood that a balance must be struck between a reasonable <br />inquiry into the site conditions and an exhaustive analysis of each conceivable environmental <br />characteristic. <br />Conditions of interest may exist at the site that cannot be identified by visual observation alone. <br />Where subsurface exploratory work is performed, our professional opinions are based in part on <br />interpretation of data from discrete sampling locations that may not represent actual conditions or <br />unsampled locations. If conditions of interest are not identified during performance of the work, <br />such a finding should not be construed as a guarantee that such conditions do not exist at the site. <br />This work was prepared in accordance with generally-accepted engineering principles and practices <br />in San Joaquin County at the time the work is performed. This warranty is in lieu of all other <br />warranties, either expressed or implied. This report was prepared for the sole use of the client and <br />appropriate regulatory agencies. Any reliance on this report by a third party is at such party's sole <br />risk.