WORK PLANS - Laserfiche WebLink

Home Browse Search

California Regional Water Quality Colrol Board Ninston H. Hickox Secretaryfor Environmental Protection 20 March 2003 Ms. Linda M. Gonsalves Central Valley Region Robert Schneider, Chair Sacramento Main Office Internet Address: httpl/w .svacb.m.gov/- gcb5 3443 Routier Road, Suite A, Sacramento, California 95827-3003 Phone (916) 255-3000 • FAX (916) 255-3164 Pacific Gas and Electric Company California Gas Transmission 375 North Wiget Lane, Suite 200 Walnut Creek, California 94598-2412 AUTHORIZATION TO ABANDON SELECT MONITORING WELLS, PACIFIC GAS AND ELECTRIC, McMULLIN DEHYDRATOR STATION, SAN JOAQ UIN COUNTY We have reviewed the 6 January 2003 Remediation Completion Report (Report) submitted by CH2MHil1 on behalf of the Pacific Gas and Electric Company (PG&E) for the McMullin Dehydrator Station (site). The site is an inactive PG&E facility that was used to dehydrate natural gas as part of its natural gas gathering system. The site is at Airport Way and Perrin Road, about two miles south of Manteca in San Joaquin County. The Report details soil excavation and confirmation sampling results and contains a request to abandon Monitoring Wells MW -3 and MW -4. PG&E has sampled the monitoring wells at this site since March 1998, and continuous quarterly sampling has occurred since July 1998. During the continuous quarterly monitoring, benzene, ethylbenzene, total petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd) were not detected in MW -3 and MW -4. Toluene and xylenes were detected during a single monitoring event in MW -3 at 4 µg/1 and 3.1 µg/1, respectively. Toluene and xylenes were also detected during a single monitoring event in MW -4 at 2.3 µg/1 and 2.2 µg/1, respectively. The toluene and xylene detections were an anomaly and are likely artifacts of sampling. The detected concentrations for toluene and xylenes are below the water quality objective for taste and odor, which are 40 µg/1 and 20 µg/l, respectively. As part of Monitoring and Reporting Program No. 5-01-857 (MRP), PG&E will continue to sample PZ -3, which is an appropriate downgradient monitoring point for the former sump. PG&E may proceed to arrange with San Joaquin County Department of Environmental Management for the permitted abandonment of MW -3 and MW -4 only. As part of the excavation work, PG&E abandoned five monitoring wells (MW -2, 5, 6, 7 and 8) and one piezometer (PZ -2) and reinstalled one monitoring well (MW -2R). Thus, revising the MRP is appropriate to require sampling at monitoring wells MW -1 and MW -2R and piezometers PZ -1, 3 and 4. Enclosed is a draft MRP for your comment that reflects these changes. California Environmental Protection Agency eteeycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consurrtption. For a list of -:_i. ....... ..... --- -..A..-. d...-.-r...A.... ..........-.............. n... Wh-e:b It hnn//.v.v,v a h ra oov/rwarh5