ARCHIVED REPORTS XR0003363 - Laserfiche WebLink

Home Browse Search

S EC01R . 7-Eleven Store #14117 Additional Site Assessment Report and Fate and Transport Model February 27, 2004 Page 3 Soil Sampling Soil samples were collected at five-foot intervals using a split spoon sampler lined with 2-inch diameter by 6-inch-long brass sample tubes Downhole drilling equipment was steam cleaned before drilling each borehole, and sampling equipment was cleaned between each sampling interval Each soil sample was screened for hydrocarbon vapors using a portable photoionization detector (PID) Soils encountered during drilling were logged using the Unified Soil Classification System by a SECOR field geologist, working under the supervision of a California registered geologist Selected soil samples were sent to Kiff Analytical in Davis, CA and analyzed for TPHg, benzene, toluene, ethylbenzene, and total xylenes (BTEX), acetone, and fuel oxygenates MtBE, ethyl-tert-butyl ether (EtBE), diisopropyl ether (DIPS), tert-amyl-methyl ether (TAME), tert-butyl alcohol (TBA), methanol, ethanol, 1,2-dichloroethane (1,2-DCA), and ethylene dibromide (EDB) by EPA Method 8260B Grab Groundwater Sampling Groundwater samples were collected at ten-foot intervals using a Hydropunch sampling device Downhole drilling equipment was steam cleaned before drilling each borehole, and sampling equipment was cleaned between each sampling interval Selected groundwater samples were sent to Kiff Analytical in Davis, CA and analyzed for TPHg, BTEX, acetone, and fuel oxygenates MtBE, EtBE, DIPE, TAME, TBA, methanol, ethanol, 1,2-DCA, and EDB by EPA Method 8260B Groundwater samples were analyzed for nitrate/nitrite as nitrogen by EPA Method 353 3, orthophosphate as phosphate by EPA Method 365 2, total Kjeldahl nitrogen by EPA Method 351 3, sulfate by EPA Method 300 0, and dissolved iron by EPA Method 60108 Lrthology Based on the description of the soil samples collected from the two borings, the lithology encountered consists mainly of interbedded clay and sand layers in MW-8 from ground surface to total depth (50 feet bgs) In SB-1, several thin silt beds were also interbedded with the clay and sand layers The clay beds observed at five feet bgs in SB-1 and 35 feet bgs in MW-8 had high plasticity No obvious low permeability, confining layer of clay or silt was observed in the soil borings Copies of the soil boring logs are included in Attachment B Well Installation Monitoring well MW-8 was constructed using 2-inch diameter PVC casing and 0 020-inch slotted well screen The well screen was installed from 40 feet bgs to 50 feet bgs (Table 1) A sand filter pack was placed within the annulus of the well from the bottom of the boring to approximately one foot above the top of the well screen The annulus of each well was sealed with two feet of bentonite on top of the sand that was capped with a Portland cement/bentonite slurry to the surface The well was sealed using a locking expansion cap An 8-inch-diameter, traffic-rated, watertight street box was installed to protect the well from surface traffic Copies of the field notes documenting the well installations are provided in Attachment C Morrow Surveying, a certified surveyor for the State of California, surveyed the locations of the newly . installed wells The top of casing of the newly installed wells were surveyed to within 0 01 feet relative to mean sea level A copy of Morrow's well survey map is included in Attachment D 14117 Vertical Assessment and Fate and'transport Model doc SECOR International Incorporated