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and California Regional Water Quality Control Bo Central Valley Region' Robert Schneider, Chair Gray Davis Winston H. Hickox Governor Secretaryfor Sacramento Main Office Environmental Internet Address: http://www.swrcb.ca.gov/—rwgcb5 Protection 3443 Routier Road, Suite A, Sacramento, California 95827-3003 Phone (916) 255-3000 •FAX (916) 255-3015 (_D� [E� 2 April 2003 APR n 3 2003 EN'vlh,_'�I'4-Ll i HEALTH Mr. William Barber PERMIT/SERVICES Group Environmental Management Company 4850 East 49th Street Cuyahoga Heights, Ohio 44125 SOIL VAPOR SURVEY WORK PLAN, BP CHEMICALS INC./ APPLIED AEROSPACE STRUCTURES CORPORATION, STOCKTON, SAN JOAQUIN COUNTY We have reviewed the 6 March 2003 Soil Vapor Survey Work Plan (Work Plan) for the BP Chemicals Inc./Applied Aerospace Structures Corporation (BP/AA) site in Stockton, submitted on your behalf by Parsons Engineering Sciences. Parsons submitted the Work Plan in response to our 21 January 2003 letter requesting implementation of the Contingency Plan, approved by Regional Board staff in our 15 September 2000 letter, because of continued detection of trichloroethylene (TCE) pollution in monitoring well MW -5R. The Contingency Plan is meant to investigate a potential source area in the vicinity of this well. We have the following comments on the Work Plan. 1. The Work Plan proposes collecting soil gas samples at three depths in each of eight locations for a total of 24 samples. The proposed locations are acceptable; however, there are no sample points proposed between the monitoring well and the open field to the south. Although the space between the well and the field is limited, a sampling point here could provide useful information in the event the source area is in the field. Therefore, the Work Plan should add a sampling point in this area. 2. As stated in the Work Plan, Regional Board staff is concerned that soil moisture from recent precipitation events may mask vapor from potential source areas in the near -surface soil. Rather than tying conduct of the survey to rises in the groundwater levels, we prefer to wait about three weeks after the last significant precipitation event prior to proceeding with the survey. A conference call could be utilized to confirm site conditions prior to proceeding. The Work Plan is approved on the condition that it incorporates the above comments. By 15 May 2003, provide a schedule to conduct the soil vapor survey. If you have any questions, you may contact me at (916) 255-3077 or by email at diuthgnrb5s.swrcb.ca,_gov. GERALD J. DJUTH, P.E., C.E.G. Associate Engineering Geologist - cc: Ms. Margaret Lagorio, San Joaquin County Public Health Services, Stockton Mr. Fred Kintzer, Parsons Engineering Science, Inc., Walnut Creek California Environmental Protection Agency ea Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can do to reduce demand and cut your energy costs, see our Website at http://www.swrcb.ca.gov/rwgcb5.