ARCHIVED REPORTS XR0009674 - Laserfiche WebLink

Home Browse Search

intervals and recorded (Table 2) . The purge water was placed in DOT-approved drums and stored on-site. ' 3. 6 Groundwater Sample Collection Water samples were collected from each well using new disposable plastic bailers. Three 40 ml EPA vials and two 1-liter amber bottles of water were collected from each well and transported in a chilled container to Alpha Laboratories in Ukiah. Each sample was analyzed for TPH as gasoline and diesel and BTE&X in accordance with EPA methods 8015m and 602 . 3.7 Monitoring Well Surveying On July 27 , 1993 , monitoring wells MW-4 and MW-5 were surveyed relative to MW-1. A survey rod and level were used to measure the elevation of the top of the well casings to the nearest . 01 foot. A notch was cut into the top of the casing as a reference point for future measurements. 4 . 0 FINDINGS 4.1 Stratigraphy The generalized stratigraphic sequence in the borings consisted mostly of brown and gray fine sand, clayey silt and sandy silt to 40 feet. Dark green sand, gravel and clayey silts were encountered from a depth of 40 feet to the bottom of the borings. No organic vapors were detected in the auger returns or soil sample duplicates (see attached boring logs. ) 4.2 Laboratory Results of Soil Samples No contamination was detected in the four soil samples analyzed ' from MW-4 and MW-5 (Table 3) . The Laboratory results and chain of custody are included in Appendix A. 4.3 Groundwater Elevation The relative groundwater elevations for the monitoring wells were calculated by subtracting the water depth from the casing elevation (Table 1) . Comparison of the November and June measurements indicates that water levels have risen approximately 5 feet at the site. This rise in water levels is probably due to groundwater recharge from the winter rains. 4 .4 Groundwater Flow Direction and Gradient Based on depth-to-groundwater measurements from monitoring wells MW-1, MW-2 and MW-3 , the hydraulic gradient was calculated to be 4