Laserfiche WebLink
Mr. Maurice Benson <br /> July 28, 2009 <br /> Page 3 <br /> 8. Page 4-6, section 4.4.3: The screening risk assessment for chloromethane <br /> included the exposure pathways of ingestion and inhalation, yet the dermal <br /> pathway was not mentioned. If it is assumed that potential receptors would be <br /> residential consuming tap water, then dermal contact would be also considered <br /> as a potential exposure pathway and included in the risk calculations. DTSC <br /> recommends this section is modified to included dermal contact under a <br /> residential use scenario and revise the "level of concern" concentration for <br /> chloromethane. <br /> 9. Page 5-5, table 5-1, Potable Well Sampling Frequency and Rationale; Potable <br /> Well (PW) PW010 at the Lathrop Sand Mobile Home Park is scheduled for <br /> abandonment and destruction once a hookup to the City of Lathrop water supply <br /> is completed. DESJC should provide an updated status of PWO10 sampling <br /> efforts in the report to reflect recent correspondence presented to the agencies <br /> from Mr. Robert Stinson, owner of the Lathrop Sands Mobile Home Park. <br /> 10. Table & Figure 5-1, Potable Well & Sampling Frequency Decision Logic; DT 3C <br /> and the regulatory agencies participated in revised monitoring well and potable <br /> well decision logic as part of the finalization of the 2008 Annual Progress Report <br /> for both Sharpe and Tracy sites. During these discussions major reductions in <br /> sampling frequencies at both types of wells were agreed upon based on revised <br /> decision logic. These discussions with URS and DESJC started in December <br /> 2008 and continued through the end of February 2009, until agreement from all <br /> stakeholders was obtained. <br /> DTSC considers the proposal to again modify the DDJC-Sharpe well sampling <br /> frequencies after only 6 months premature. DTSC will reserve its comments and <br /> approval of the Potable Well Evaluation sampling frequency, until a year's worth <br /> of monitoring data is obtained under the currently sampling logic. DTSC <br /> envisions revisiting the proposed decision logic for both monitoring and potable <br /> wells during its review of the 2009 Annual Progress Report for the Sharpe and <br /> Tracy sites in combination with modeling data to reference two lines of evidence. <br />