SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Moore Truck Lines - 3 - 25 May 2012 3400 Newton Road Stockton, San Joaquin County 2008 to present. The extent of the groundwater plume is defined as 10' to the northwest of non-detect MW-8 to 30' to the east of MW-1, based on groundwater results from nearby borings and monitoring wells MW-2, MW-3, MW-6, and MW-7. Groundwater monitoring since 1999 shows the MTBE plume (the TPHg is primarily MTBE, with no B-T-E-X reported since August 2002) around MW-1 is stable though very slowly declining in concentration. Monitoring continued until June 2009, when all work stopped due to the financial hardship of the responsible party (RP). On 20 December 2010, the San Joaquin County Environmental Health Department referred the Site to the Regional Board for recalcitrance. Regional Board staff (Staff) met with the representative (son) of the RP on 4 January 2011. Groundwater monitoring resumed in February 2011 and ended with Staff approval in August 2011. It was determined that additional work to conduct limited remediation was no longer cost effective, nor was it necessary to continue monitoring the small stable plume that 11 years of groundwater monitoring show is not threatening sensitive receptors. Risk Assessment The residual soil contamination is very limited in extent and is not leaching into groundwater at a sufficient rate to threaten the Site supply well (DM-1) or other sensitive receptors. Residual petroleum hydrocarbons in Site soil and groundwater pose a minimal threat to human health or the environment. Due to the distance to Site buildings (over 90' to the office/shipping dock/distribution center, and 30' to the truck shop) and due to the construction of the large open paved truck yard, Staff did not require a soil vapor survey. Land use (commercial) is not expected to change in the foreseeable future. Estimates for time to reach water quality goals (WQGs) are MTBE by 2026 and TPHg by 2070. Sensitive Receptor Survey A sensitive receptor survey conducted in 2010 identified 10 domestic supply wells (businesses) and one municipal supply well located within 2000' of the site. The nearest domestic well (DM-1) is 134' to the north of the former USTs. The nearest offsite domestic well is 300' to the north. The municipal well is 1,500' to the southwest. Although there are multiple USTs cases in the vicinity of the Site with their own groundwater plumes, none of the supply wells are threatened by the petroleum hydrocarbons release at this Site. Site Geology and Hydrogeology Site lithology consists of silty clay with discontinuous lenses of sand from surface to 50' bgs. Silty sand, sandy silt and silty clay were logged from 50' to 64' bgs; sandy silt and silt were present from 64' to 72' bgs; clay reported from 72' to 77' bgs;