ARCHIVED REPORTS_XR0012170 - Laserfiche WebLink

Home Browse Search

Unocal Service Station No 0187 September 21, 1994 The clay is underlain by a sandy unit to approximately 55 feet bgs, except in well boring U-2 The sands in this unit have varying amounts of clay, and range from clayey sand (SC) to well-graded sand (SW) In well borings U-3 and U-1 , clay (CL) was encountered in the bottom one-foot of each boring In well boring U-2, approximately three feet of sandy clay at approximately 40 feet bgs, but this was underlain again by clay to approximately 57 feet bgs, where clayey sand was again encountered Clayey gravel (GC) was encountered to a depth of approximately 14 feet bgs in exploratory soil boring U-G. This material is imported fill placed in the former UST excavation Brick and the fragments encountered in Borings U-A and U-D and other man-made debris encountered during UST and product line removal indicate the uppermost ten to twelve feet of soil beneath the site is fill material Soil relations are depicted on cross-sections A-A' and B-B' (Figures 3 and 4 respectively) Groundwater Conditions Groundwater was first encountered in well borings U-1 , U-2, and U-3, and exploratory soil borings U-L and U-M at depths ranging from approximately 45 to 51 feet bgs Depth-to-water measurements from the top of the well casing, taken prior to well development, ranged from 46 91 to 47 38 feet Based on these data, shallow groundwater beneath the subject site appears to be flowing south at a gradient of 0 004 CHEMICAL ANALYTICAL RESULTS A total of 23 soil samples from the well and exploratory soil borings and one sample from the stockpiled drill cuttings were submitted for chemical analysis All soil samples were analyzed for TPH-Gasoline and BTEX by EPA Methods 8015 (Modified) and 8020, respectively One sample from well boring U-1 at 6 5 feet bgs was also analyzed for cadmium (Cd), soluble chromium (Cr), soluble lead (Pb), and soluble nickel (Ni) by the Waste Extraction Test (WET) with a de-ionized water extractant One groundwater sample from Well U-2 was collected subsequent to well development and was used to perform a fish bioassay using Report No 4627 703 5 [j GeoStrategies Inc.