SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

California Rcvronal Water Quality G Atrol Boarda Central Valley Region Robert Schneider,Chair Winston H.Hickox Gray Davis Secretaryfor Sacramento Main Office Governor Environmental Internet Address: http://www.swreb.ca.gov/—rwgcb5 Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 Phone(916)255-3000•FAX(916)255-3015 5 February 2002 Z 2� Mr. Robert Mihalovich Chevron Environmental Management Company 6001 Bollinger Canyon Road P. O. Box 6012 San Ramon, CA 94583-0712 LOW-RISK CLOSURE REQUEST, CORRAL HOLLOW AND GRANT LINE ROADS SITE, TRACY, SAN JOAQUIN COUNTY We have reviewed Geomatrix Consultants' 12 July 2001 Response to RWQCB May 10, 2001 Comments (Low-Risk Closure Request) (Response) for Chevron Environmental Management Company's (Chevron) site at Corral Hollow and Grant Line Roads in Tracy. The Response provides justification for selecting natural attenuation as the remedial alternative to clean up the petroleum hydrocarbon pollution at the site. In addition, the Response provides a hypothetical analysis of the effects of applying oxygen releasing compounds (ORC) to address our request for a pilot study to obtain more accurate information on the time to remediate the site using ORC. The Response states that the information obtained from the ORC pilot study would be limited to the frequency of ORC replacement at the site for the first year, and would not provide additional information regarding the time of remediation. We concur with these statements. However, according to the 2001 Second Semi-Annual Monitoring Report, the current highest concentrations of benzene, toluene, ethylbenzene, xylenes and total petroleum hydrocarbons as gasoline (TPHg) are 68, 7, 350, 160, and 3,400 µg/l, respectively. While these levels show a continued declining trend, all of them except toluene are still above their respective water quality objectives (WQOs) of 0.1, 29, 42, 17, and 5 µg/l. Chevron proposes to rely on natural attenuation to remediate the groundwater to meet the WQOs, but does not propose any ongoing monitoring. This is unacceptable. At the very least, Chevron must continue monitoring the groundwater at the site. The U.S. Environmental Protection Agency's (USEPA) April 1999 Directive, Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites, states: 1. USEPA does not view monitored natural attenuation (MNA) to be a"no action "or"walk-away" approach, but rather considers it to be an alternative means of achieving remediation objectives that California Environmental Protection Agency Oy* 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.