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• Phase II Environmental Site Assessment
<br /> Mountain House Neighborhood G
<br /> July 9,2002
<br /> Page I]
<br /> 8.0 CONCLUSIONS
<br /> Condor conducted a Phase II Environmental Assessment for the proposed Neighborhood G site located in
<br /> western San Joaquin County in Mountain House, California in general accordance with the Phase 11
<br /> Environmental Site Assessment Work Plan, prepared by Condor,dated September 25, 2001. As indicated in
<br /> Section 2.0, the site has historically been used for agricultural purposes prior to 1990. One set of five two-
<br /> to-one composite surface samples (sample numbers 1-2, 3-4, 5-6, 7-8, and 9-10) were collected at the site
<br /> and analyzed for organochlorine pesticides by EPA Method 8081A and chlorinated herbicides by EPA
<br /> Method 8151 A.
<br /> The laboratory analytical results indicate that the organochlorine pesticides gamma-BHC (lindane), DDD,
<br /> DDE, DDT, endosulfan I, endosulfan II, endrin, endrin aldehyde, heptachlor, and kepone, and the
<br /> chlorinated herbicide MCPP were detected in the composite samples. Each of these constituents was
<br /> detected below the laboratory reporting limits and the reported values are estimated concentrations.
<br /> The organophosphorus pesticides azinphos-methyl, bolstar, chlorpyrifos, coumaphos, demeton, diazinon,
<br /> dimethoate, disulfoton, ethoprop, ethyl parathion, famphur, fensulfothion, fenthion, merphos, methyl
<br /> parathion, mevinphos, 0,0,0-triethylphosphorothioate, tetrachlorvinphos, thionazin, tokuthion, and
<br /> thrichloronate were detected in at least one of the discrete soil samples analyzed for these constituents.
<br /> Ethoprop, fenthion, merphos, methyl parathion, 0,0,0-triethylphosphorothioate, thionazin, and
<br /> trichloronate were detected above reporting limits in the discrete samples and were not detected in the
<br /> method blank. Azinphos-methyl, coumaphos, and dimethoate were detected in the method blank, indicating
<br /> that the reported concentrations of these constituents may be higher than their actual concentrations in the
<br /> soil samples. All constituents were detected below the United States Environmental Protection Agency
<br /> F Region 9 Preliminary Remediation Goal (PRG) values. Residential PRGs are not established for the
<br /> (` organochlorine pesticides endosulfan 1, endosulfan II, and endrin aldehyde or for the organophosphorus
<br /> pesticides azinphos-methyl, bolstar, coumaphos, ethoprop, famphur, fensulfothion, fenthion, mevinphos,
<br /> 0,0,0-triethylphosphorothioate,thionazin, tokuthion, and trichloronate.
<br /> Gamma-BHC, DDD, DDE, DDT, endosulfan 1, endosulfan II, endrin, endrin aldehyde, heptachlor, kepone,
<br /> MCPP, azinphos-methyl, bolstar, chlorpyrifos, coumaphos, demeton, diazinon, dimethoate, disulfoton,
<br /> ethoprop, ethyl parathion, famphur, fensulfothion, fenthion, merphos, methyl parathion, mevinphos,
<br /> 0,0,0-triethylphosphorothioate, tetrachlorvinphos, thionazin, tokuthion, and were identified as COPC
<br /> based on their varied presence in several on-site composite and discrete samples and underwent HHRA
<br /> analysis. Cancer risk and hazard quotient were calculated for the COPC. Cumulative lifetime cancer risk
<br /> for all constituents of concern with published toxicity reference values is 4.57E-07, and the cumulative
<br /> hazard for all constituents of concern is below unity (I.00E-01). Therefore, the COPC pose no significant
<br /> health hazard. Based on review of the background information referenced in Section 2.0, the site visits
<br /> performed by Condor, the laboratory analytical results of soil samples collected during the Phase II ESA,
<br /> and risk and hazard calculations,Condor concluded the following:
<br /> 1. Past practices of handling agricultural chemicals have not resulted in a significant release or threat at
<br /> the site.
<br /> 2. There is no immediate potential hazard to public health or the environment.
<br /> Based on these conclusions, Condor believes that additional investigation and remediation are not
<br /> necessary at this time and recommends no further action.
<br /> A
<br /> i, CONDOR
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