ARCHIVED REPORTS_VAPOR INTRUSION SURVEY - SOIL GAS SAMPLING REPORT

Home Browse Search

Former Columbo/Toscana Bakery - 2 - 23 December 2008 ' 1444 S. Lincoln St., Stockton ' estimated from $401,000 to $600,000 (cost varied due to uncertainty of disposal options, whether in-state or out of state). ' • ISCO (injecting modified Fenton's Reagent with Hydrogen Peroxide) was given a good short-term effectiveness rating and a very good long-term effectiveness, if three (3) separate injection mobilizations are conducted at depths of 25', 50', and 80' bgs; however, the $300,000 estimated cost was cited as the reason for not recommending ISCO. ' • BioS would target the USTs source area with four air injection wells screened at 55' and 80' bgs, injecting air at very low volumes (2 to 4 standard cubic feet per minute). BioS was given a minimal short-term effectiveness rating due to the anticipated slow ' biological response to the injection of air into the aquifer, and a very good long-term potential for success since the BioS system could be expanded offsite for a commingled plume, at an estimated cost of$145,000 over three years. ' While BioS was selected as the preferred technology, the Report did not include a recommendation for a BioS pilot study or a BioS workplan, nor provide a schedule for ' conducting BioS remediation. Instead, the Report recommended that "...remedial corrective actions..." be implemented upon establishment of the State Water Resources Control Board Underground Storage Tank Cleanup Fund Commingled Plume Account (SWRCB CPA) letter ' of commitment (LOC), to "...make the most efficient use of the corrective measures the technology and would reduce expenses..." The Report did not include an anticipated time schedule for receipt of the SWRCB CPA LOC. ' I also reviewed an email (Emaio from PSC dated 10 November 2008, a routine monthly update of the status of the SWRCB CPA LOC acquisition efforts by parties managing ' neighboring USTs sites. The Email also included a proposed schedule for implementation of an approved workplan and the report submittal for the soil vapor intrusion (SVI) investigation. The SVI workplan was approved by my Letter, which also requested a schedule for ' implementation of the SVI fieldwork, and submittal of the SVI report by 10 November 2008. The Email stated that there were concerns with false positives from the proposed soil gas testing (due to offsite sources mixing with onsite sources), and that questions on the fate and ' transport of the commingled plume would be answered by coordination of the proposed CPA sites monitoring in 2009. The Email suggested delaying the implementation and reporting of the SVI for one year, until the fourth quarter of 2009. ' Comments: ' 1. While Regional Board staff appreciate the extensive investigative work that Sara Lee has accomplished since taking over the site in 2007, the Report proposal to delay a remediation focused on your source area until after receipt of the SWRCB ' CPA LOC was addressed previously in my Letter, and also during our subsequent meeting on 18 September 2008. Both times staff stated that efforts to recruit applicants for the CPA should not adversely affect the cleanup progress of those sites involved in the CPA process. In fact, three nearby USTs sites that you have ' contacted for the CPA are conducting remediation efforts as: 1) full scale SVE/AS