ARCHIVED REPORTS_XR0004018 - Laserfiche WebLink

Home Browse Search

i Soil and Groundwater Investigation Page 4 Former Dolly Madison Facility Project No 2002-1426-02 October 27, 2000 FINDINGS Site Geology and Hydrogeology Based on the CPT data from boring B-4/CPT-1 and boring B-5/CPT-2, the soil beneath the site is primarily silt and clayey silt Silty sand and sand was encountered from 31 to 33 feet, 66 to 68 feet and 99 to 102 feet bgs in boring B-4/CPT-1 and from 13 to 14 and 39 to 41 feet bgs in boring B-5/CPT-2 Based on a comparison of the results of the two CPT tests, the silty sand and sand layers are not likely to be laterally continuous Sand and gravelly sand was encountered from 83 to 87 feet bgs in boring B-5/CPT-2 Sand and gravel have been reported at similar depths in previous offsite investigations and may indicate some degree of lateral continuity of this material Groundwater was encountered at approximately 19 feet bgs during this investigation Stratus submitted five soil samples to Sierra Testing Laboratories of El Dorado Hills, California for permeability testing Samples were analyzed using ASTM Method D5084- 91 Three samples were analyzed from boring B-4/CPT-1 and two samples were analyzed from boring B-5/CPT-2 Sample B4-21-S (clayey silt), collected within 10 feet of the bottom of the former UST complex (21 feet bgs), was tested to have a permeability of 3 6 * 10-6 cm/sec (1 14 m/yr) Sample 134-64-S (clayey silt, 64 feet bgs) was tested to have a permeability of 9 4 * 10'7 cm/sec (0 29 m/yr) and sample 134-78-S (silt with 10% fine grained sand, 78 feet bgs) was tested to have a permeability of 6 6 * 10-5 cm/sec (20 81 m/yr) Sample 135-20-S (silty clay, 20 feet bgs) was tested to have a permeability of 3 5 * 10-7 cm/sec (0 11 m/yr) and sample 135-59-S (clayey silt with 5-10% fine grained sand, 59 feet bgs) was tested to have a permeability of 2 3 * 10-7 cm/sec (0 073 m/yr) The permeability results from the two samples analyzed from 20 and 21 feet bgs. indicate that downward migration of petroleum hydrocarbons should be strongly retarded by the subsurface stratigraphy at this depth The laboratory report for the permeability testing is included with the soil sampling logs in Appendix B Analytical Results Six soil samples were analyzed from boring B-4/CPT-1 and five soil samples were analyzed from boring B-5/CPT-2 TPHG was detected at a maximum concentration of 4,800 mg/Kg in the soil sample collected from 14 feet bgs in boring B-4/CPT-1 TPHG was not detected in any of the soil samples collected from boring B-5/CPT-2 Benzene was detected in soil samples collected between 21 and 64 feet bgs in boring B-4/CPT-1 at concentrations ranging from 25 }tg/Kg to 400 gg/Kg and in soil samples collected between 37 and 101 feet bgs in B-5/CPT-2 at concentrations ranging from 19 pg/Kg to 84 gg/Kg Oxygenates, EDB and DCA were not detected in any of the soil samples collected from either boring The analytical results for all soil samples collected during this investigation are presented in Table 1 and copies of the certified analytical reports and chain-of-custody documentation are located in Appendix C P lI B ClStockton\ReportsllBC Soil and Groundwater report Oct 2000 doc STRATUS