Laserfiche WebLink
CH2M HILL <br /> 155 Grand Avenue <br /> Suite 1000 <br /> Oakland, CA <br /> C:H2MHIL1 L 94612 <br /> P.O. Box 12681 <br /> Oakland, CA <br /> 94604-2681 <br /> Tel 510,251,2426 <br /> Fax 510.893.8205 <br /> August 19,2002 <br /> Ms.Mary Serra <br /> Water Resources Control Engineer <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 3443 Routier Road,Suite A <br /> Sacramento,CA 95827 <br /> Subject: Implementation Plan for Interim Remedial Action at the PG&E McMullin <br /> Dehydrator Station <br /> Dear Ms.Serra, <br /> On behalf of Pacific Gas and Electric Company(PG&E),CH2M HILL is submitting an <br /> implementation plan for the interim remedial activities at the McMullin Dehydrator Station <br /> (site) in San Joaquin County,California (Figure 1). This letter is a follow-up to the Supplemental <br /> Site Assessment and Interim Remedial Action Plan, TRAP, CH2M HILL,2002 that was previously <br /> approved in December 2001. <br /> This letter describes interim remedial activities and presents preliminary design drawings. The <br /> purpose of the remedial action is to address petroleum hydrocarbons in the subsurface soil and <br /> groundwater at the facility. A brief background of the site,rationale of the proposed interim <br /> remedial action,description of the proposed excavation activities,verification sampling and <br /> schedule are discussed below. <br /> Background <br /> The Station was built on PG&E's property in 1961 and is currently inactive. The site is located <br /> near the intersection of Airport Way and Perrin Road,approximately 2 miles south of Manteca. <br /> The site is approximately 85 feet wide by 100 feet long and is surrounded by a chain link fence. <br /> The station currently includes a control building and odorizer equipment. The site surface <br /> consists of a thin gravel layer (6-inches) over clayey sand. PG&E used the station for odorizing <br /> and removing production fluid in natural gas to prepare the gas for transport in its gas <br /> transmission system. <br /> Figure 2 depicts the site layout,including former production equipment and locations of soil <br /> borings, monitoring wells and piezometers. Based on the boring logs, the subsurface soils <br /> throughout the site appear to consist primarily of interbedded clay and silt.Groundwater levels <br /> recorded over the last three years indicate that the groundwater generally fluctuates between 7 <br />