ARCHIVED REPORTS_XR0004063 - Laserfiche WebLink

Home Browse Search

Po,mbo Ranch Facility April 24,2005 Remedial Excavation&Source Removal 16 Y Apparent contamination extended in a north to northeast direction and the lateral limits of the excavation resulted in an irregular shape 65' to the east of the former underground tank and 50 to 62 feet north of the 65'south lateral line (see Figure 2). Monitoring well MW-4, located within the area of excavation was destroyed. The well is scheduled for replacement on May 4, 2005 just outside the excavated area. Confirmation samples were collected from each of the four sidewalls of the excavation at ' about ten feet in depth. Gasoline hydrocarbons were not detected in the samples above reporting limits. Kerosene range hydrocarbons were present in very low levels in two of the samples. Volatile aromatic hydrocarbons were detected in low concentrations on the ' west wall and in moderate concentrations on the east wall. None of the Oxygenated Compounds, including MTBE, were present in the confirmation samples. Lead levels were similar to the pre-qualification sample levels. Confirmation Iaboratory sample ' results are shown in Appendix B. Table of Anal tical Results 03/01/05 Sample Gasoline TEPH Benzene Toluene E-Benzene Xylenes Oxys Lead I.D. m /K m /K /Kg jug/Kg REESm aN CW-1-10' <1.0 29 <5.0 <5.0 19 19 ND 5.6 CS-2-10' <1.0 <1.0 <5.0 <5.0 <5.0 <5.0 ND 5.6 CN-3-10' <1.0 <1.0 <5.0 <5.0 <5.0 <5.0 ND 5.0 CE-4-10' <1.0 37 <500 1 <500 670 1290 ND 5.5 ND=Non Detect 1,524.71 tons of excavated soils were removed from the site and transported to Forward Landfill for disposal. Disposal Activity Reports are shown in Appendix C. Due to ' seasonally late rain the soil had to be transported over a number of weeks. Since the soil was damp and "sticky", and had a tendency to stay in the trailer, vegetable oil was used to lubricate the 33 foot long end dump trailer between each load. The excavation was backfilled with clean soils segregated from the excavation and soil provided by Pombo from an onsite source. The surface was graded and the base rock or road base replaced. ' 2.1 Soil Sampling ' All soil sampling equipment was thoroughly cleaned before and between sampling to prevent cross contamination. Relatively undisturbed soil samples were with a spoon sampler on a pole when access was available otherwise the sample was collected with the backhoe bucket and placed in a brass tube. The laboratory samples did not have head space and were immediately sealed in their liners using plastic caps. Soils were collected at 10 foot depths from each sidewall for laboratory analysis. All soil samples were delivered, under chain of custody, to an analytical laboratory licensed by the State of California for hazardous materials work. The samples were analyzed for ' gasoline and gasoline constituents and TEPH for diesel-kerosene-motor oil range petroleum hydrocarbons, the Oxygenated Compounds and lead. 7