WORK PLANS - Laserfiche WebLink

Home Browse Search

Additional Soil and Groundw�rrer Investigation Work Plan CCT Stockton Rail Yard, 1645 Cherokee Lane, Stockton,CA October 4, 2007 Page 3 July 12, 2000: HETI drilled six soil borings (B-1 through B-6)to total depths of 50 fbg. Grab groundwater samples were collected each of these borings. Analytical results for all soil and grab groundwater samples for total petroleum hydrocarbons as gasoline (TPH-g), TPH-d, BTEX constituents, and five oxygenates were all below reported laboratory limits (HETI 2001). The locations of these borings are show on Figure 3. August 28-29, 2000: HETI constructed three groundwater monitoring wells (MW-1, MW-2, and MW-3)to 50 fbg with 15 feet of screen (Figure 3). Soil samples were not collected for analysis from wells MW-1, MW-2, and MW-3 due to the close proximity of previously installed borings B-1, B-4, and B-5, respectively. Soil analytical data from borings B-t, B-4, and B-5 are available in Appendix Al. TPH-d was detected in groundwater samples collected from each of the three wells. Quarterly monitoring was initiated in September 2000 (HETI 2001), and continued through February 2002. The wells were dry during both the November 2001 and February 2002 monitoring events (HETI 2004). Groundwater data collected from these wells are included in Table 1. These were subsequently destroyed in 2005 in preparation for site excavation activities. August 20, 2001: HETI installed an additional groundwater monitoring well (MW-4) in the former diesel UST excavation (HETI 2004). June 2004: HETI advanced five additional soil borings (B-7 through B-11) to total depth of 50 fbg. All analytical results for TPH-g and BTEX constituents were below laboratory reporting limits. TPH-d was detected in soil samples at a maximum concentration of 4,300 mg/kg in the sample collected at 25 fbg from B-11. Soil analytical results are included in tabular form in Appendix A2. TPH-d was detected in two grab groundwater samples at a maximum concentration of 2,900 micrograms per liter(�tg/L) in the sample collected from B-8 (HETI 2004). These data are included in Table t. June 14-15, 2005: Four groundwater monitoring wells (MW-1 through MW-4) were abandoned by over drilling in preparation for site excavation activities. June to December 2005: Approximately 10,400 tons of soil was excavated from the site. The maximum depth of the excavation was 8o fbg and the diameter of the excavation was approximately 200 feet (CLS Environmental Services, Inc. 2oo6). 4.0 SUMMARY OF REMEDIAL ACTION AND HISTORICAL DATA This section presents a summary of historical data collected at the site, as well as pertinent information provided in the RAR which was submitted by CLS Environmental Services (CLS) on December 12, 2oo6. 4.1 Soil Data The area of the site which was excavated in 2005 included the vast majority of previously investigated areas. All locations sampled for soil prior to the excavation activities in 2005 (inclusive of the UST removal confirmation samples,borings B-1 through B-5 advanced in 1999, borings B-1 through B-6 advanced in 2000, wells MW-1 through MW-3 installed in 2000, well MW-4 installed in 2001, and borings B-7 through B-11 advanced in 2004) have been subsequently excavated to the total depth analyzed with the exception of B-6.