Laserfiche WebLink
Corrective Action Plan 1 1 <br /> Time Oil Company Proptrt No 04-049 14000 East Highway 88 Lockeford CA September 8 1998 <br /> bgs), and benzene In groundwater, exceed RBSLs for selected exposure pathways (Table 7) <br /> i <br /> Site-specific chemical concentrations in surface sols (< 5 feet bgs) did not exceed RBSLs fol <br /> any of the identified exposure pathways Based on these results a preliminary Tier 2 analysis was <br /> conducted <br /> 34 TIER 2 ANALYSIS: SITE-SPECIFIC TARGET LEVELS <br /> SSTLs were developed for the site using Groundwater Services, Inc Tier 2 RSCA Tool Kit <br /> version 1 01, which uses the equations developed in ASTM E 1739-95 to model SSTLs No <br /> biodegradation of petroleum hydrocarbons is accounted for in the modeling, so it is assumed that <br /> site-specific concentrations of chemicals of potential concern will remain at their maximums for <br /> the full exposure durations Only BTEX compounds were evaluated as part of the Tier 2 <br /> analysis, because site-specific concentrations of 1,2 Dlbromoethane and MTBE did not exceed <br /> Tier 1 RBSLs <br /> The following site-specific parameters were changed for the Tier 2 analysis <br /> ❑ The area of impacted soil was increased from the Tier 1 default value of 2,420 ftZ <br /> to the site-specific value of 8,500 ftz Correspondingly, the length of affected soil <br /> parallel to the wind direction was increased from 49 ft to 100 ft <br /> ® The vadose zone thickness and depth to groundwater values were increased from <br /> the Tier 1 defaults of 9 68 and 9 8 feet, respectively, to 66 8 and 67 feet <br /> M The depth to the top of impacted subsurface soils was increased from 3 28 feet to <br /> 30 feet, where maximum concentrations have been detected For off site <br /> residential exposure pathways, the depth was increased to 75 feet based on soil <br /> Time OikLockeford\CAP wpd <br />