ARCHIVED REPORTS_XR0005181 - Laserfiche WebLink

Home Browse Search

4�2 Soil Analysis Soil samples selected for laboratory analysis were kept on ice and delivered under chain-of- custody documentation to State-certified Argon Laboratories Inc. (Environmental Laboratory ' Accreditation Program Certification No. 2359) in Ceres, California for chemical analysis. These soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd) utilizing EPA method 8015M; benzene, toluene, ethyl benzene, and xylenes (BTEX) utilizing EPA method 8021B; and MTBE, ethyl tertiary butyl ether ' (ETBE), di-isopropyl ether (DIPS), tertiary butyl alcohol (TBA), tertiary amyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) by EPA method 8260B. The analytical results for soil samples are summarized in Table 1. Laboratory data sheets and chain- of-custody documentation are included in Appendix B. ' 443 Results of Soil Anal sis 4_4 Site Geology ' From the surface to 55 or 60 feet bgs, the section was predominantly inter-bedded silts and clays or silt - clay mixtures. Soil consisting primarily of silty sands or sandy silts was encountered between 55 or 60 to 80 feet. Soils encountered between approximately 80 to 85 feet bgs consisted of organic clay. Soils consisting of poorly graded sands were encountered from 85 feet to approximately 110 feet bgs. ' The initial water level was measured between 70 and 75 feet bgs in each h borings(IW1 —lW5). Soil boring logs with a detailed description of soil types are contained in Appendix A. 4.5 SnargeyointR Construction Details h IWS were R IWl through e completed as ozone infection wells with two ozone Spargepoints placed in each boring. Each SpargepointR was 1 inches in outside diameter (OD) and 30 inches in length. In each boring, the bottom of one SpargepointR was placed at an approximate depth of 107.7 feet bgs and the bottom of the second one was placed at an approximate depth of 74 feet bgs. Table 2 describes the well and SpargepointR construction details. The soil adjacent to the sparge points from between 70 and 75 feet bgs generally consisted of silts and clays and the soil from between 105 and 108 feet bgs generally consisted of sands. _-_Sparge Sparge point intervals-were saturated.- Once aturated:Once the deep SpargepointR and PVC riser had been installed at approximately maximum depth of 107.7 feet bgs, the boring was backfilled with sand from the bottom, approximately 110.5 feet bgs, to approximately 103 feet bgs. A 25-foot thick interval of hydrated bentonite was placed above the deeper sand pack and once the bentonite set, the boring was backfilled with sand from 78 feet to approximately 69 feet bgs. A 3-foot thick interval of hydrated bentonite was placed w:lwordpro1268231reportslremsysinst.doc 3