SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Tracie Billington, P.E. August 14, 1992 Page Five This statement must be qualified for OU # 1 based on the current level of knowledge. Additional investigations conducted under the site wide RI/FS may change our understanding of OU # 1. 9) Page 1-10 section 1. 2 . 4 . 5 and 1. 2 . 4 . 6 states that lead, arsenic, chromium, nitrates, and boron have been detected at elevated levels. The Department requires assurances that the questions concerning these metals will be addressed in the site wide RI/FS . 10) Page 1-17 section 1. 2 . 7 . 2 outlines the "fence line" approach for the construction of extraction wells for the IRM previously proposed for DDRW Tracy. The Department has never approved the "fence line" approach ---for the placement of extraction wells depicted in the IRM treatment alternative. The need for an evaluation of aquifer parameters and placement of extraction wells based on such parameters has always been maintained by the Department as the best construction method. 11) Page 1-19 section 1. 3 . 2 outlines a monitoring program to evaluate the ground water treatment system's performance. It has been the Department' s experience that a separate monitoring system can be confusing and detrimental to the overall project. We recommend that any separate monitoring for system performance be incorporated into the present and ongoing quarterly monitoring system. 12) Page 2-2 section 2 . 2 . 1. 1 states the objectives of the FS for OU # 1 is to identify a preferred remedial measure for the present on and off-site plume. The Department agrees with this concept and supports the establishment of OU # 1 for VOCs in the upper Tulare geologic formation. The Department does expect DDRW Tracy to fully pursue the delineation of all potential contaminants, both soil and ground water, in the site wide RI/FS. 13) Page 2-18 section 2 . 3 . 3 . 3 estimates the quantities of TCE and PCE in the ground water at 137 lbs. and 63 lbs. respectively.