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private wells in the affected area are being monitored. In addition, the CDHS Office of <br /> Drinking Water (ODW) requires that all public well water be tested for contamination every <br /> two years. If contamination is detected below standards, the well must be monitored on a <br /> quarterly basis. If contamination is found exceeding the standard, but less than 10-times the <br /> standard, the well must be monitored each month for six months. If the average of the six- <br /> monthly concentrations exceeds a drinking water standard, the water purveyor is considered <br /> to be in violation of drinking water standards and must close the well, providing public <br /> notification of the contamination. The well cannot be started up again until ODW approves a <br /> treatment and monitoring plan. If contamination is found at levels greater then ten-times the <br /> drinking water standard, the water purveyor must collect a confirmation sample. If the <br /> sample confirms significant contamination, the well must be shut down immediately and <br /> cannot be started up again until a treatment and monitoring plan is approved by ODW. <br /> No current or future exposure to contaminants in soil at levels of health concern are <br /> expected. Areas of surface soil contamination have been remediated. Contaminated soils <br /> beneath the retort pit do not present a current health threat; a site safety plan will be <br /> required, however, when that contamination is remediated in the future. <br /> Therefore, MCTC does not appear to pose a public health threat now or in the future. <br /> Communis Health Concerns <br /> No current community health concerns were reported by persons contacted for this site <br /> review and update. Persons contacted included DTSC staff, county environmental and public <br /> health officials, the principal of the adjacent high school, the local state assemblyman, the <br /> pastor of a local church, and the San Joaquin Board of Supervisors member for the East <br /> Stockton district. A Fresno County public health nurse who covers the East Stockton district <br /> described the area as having a transient and predominately Hispanic population. <br /> CONCLUSIONS <br /> Based on summary information reviewed, past exposure to arsenic and chromium in soil and <br /> air may have occurred. It cannot be determined, however, if past exposure constituted a <br /> health hazard without knowledge of the duration of exposure and the levels of exposure over <br /> time. Past exposure to chromium in groundwater may have also occurred, although data and <br /> information are insufficient to evaluate the public health significance of such exposure. <br /> Given the data and information that existed at the time the preliminary public health <br /> assessment was written, the conclusion that the MCTC site posed a public health concern was <br /> appropriate. With the exception of gathering additional demographic data, the <br /> recommendations in the preliminary public health assessment have been addressed by recent <br /> regulatory activities. Given the additional site characterization and remediation activities <br /> which have occurred since the preliminary health assessment was completed, the MCTC site <br /> does not currently present an apparent public health threat and is not expected to present a <br /> 3 <br />