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Mr. Marshall Cloud April 18, 2008 Page 2 Specific Comments 1. Page 1-1, Section 1.4, last sentence; DTSC is concerned by the exclusion of monitoring well LM151 B as part of the focused ground water extraction testing. Ground water analytical data has shown that LM151B is exhibiting increasing trends for Trichloroethene and is almost twice the Federal Maximum Contaminant Level with at 3Q07 concentration of 9.33 micrograms per liter (Ng/L). Additionally, TCE contaminants at LM151 B are outside the hydraulic influence of extraction wells EW024B and EW025B, thus allowing contaminants to migrate further down-gradient without capture. DTSC considers focused ground water extraction at LM151 B as a necessity considering the higher TCE contaminant concentrations, lack of active remediation present, and lack of remedial options for down-gradient extraction and treatment available. 2. Page 1-2, Table 1-1; Ground water analytical results for LM151 B in 3Q07 recorded a TCE concentration of 9.33 pg/L. Please amend the table to present the correct contaminant concentration for TCE at LM151 B recorded during the third quarter 2007 sampling event. 3. Page 2-4, Section 2.2.3, first sentence; The aquifer step tests lasting a period of one-week might not be enough time for the aquifer to be adequately stressed to actually observe the true drawdown available at that location. DTSC recommends a longer step draw down test to stress the aquifer help eliminate the data only showing the de-watering of the aquifer rather than the drawdown available at that time. If you have any questions or comments regarding this letter, please feel free to contact me at (916) 255-3713, or e-mail me at pmacnich(a)dtsc.ca.gov. Sincerely, Peter MacNicholl, P.E. Remedial Project Manager Federal Facilities Unit cc: See DDJC-Sharpe Distribution List.