WORK PLANS - Laserfiche WebLink

Home Browse Search

Limited Site Investigation � �erracvn Vacant Property I Tracy, California May 26, 2023 1 Terracon Project No. NA197074B SB17, SB19, SB20, SB21 and SB22 were all advanced to a total depth of approximately 30 feet below ground surface (bgs). Soil boring SB18 was advance to a total explored depth of approximately 60 feet bgs, and borings SB23 through SB26 to a total depth of 4 feet bgs. In general, two soil samples were analyzed from each of the 30 foot and 60-foot-deep borings from approximately 8 to 10 feet bgs, and near the bottom of each boring at approximately 30 feet and 58 feet bgs. Due to field observations, a shallow third sample was also analyzed from SB17 at a depth of 4 feet bgs. Soil samples from borings SB23 through SB26 were analyzed from a depth of 2 feet bgs. The soil borings and temporary sampling well (SB18) was advanced using a 31/4-inch diameter hand auger in the upper 3 to 5 feet bgs, followed by a direct-push drill rig equipped with 21/4-inch diameter drill rods and disposable acetate sample sleeves. Non- disposable sampling equipment was cleaned using a non-phosphate soap wash and potable water rinse prior to the beginning of the project and before collecting each soil sample. Terracon field-screened soil samples for organic vapors using a calibrated 5-gas meter with a photoionization detector (PID). This device provides a direct reading in parts per million by volume (ppmV) isobutylene equivalents. Upon removal of the sampler from the borehole, Terracon placed a portion of each soil sample in a sealable plastic bag. After a stabilization period, Terracon screened the headspace above the soil using the PID. PID readings were recorded during field screening at less than 1.5 ppmV in all samples screened, except in borings SB17, which had a reading of 490 ppmV at approximately 4 feet bgs. The field screening results and groundwater observations are summarized in the Soil Boring Logs in Appendix C. Soil samples were extracted by hand using disposable gloves and placed directly into laboratory-supplied glassware and submitted to the laboratory for analysis. Each sample container was labeled with the project number, date, time, boring number, and sample number. Sample containers were placed in a chilled cooler immediately after sampling, and subsequently transported to SunStar Laboratories, Inc. of Lake Forest, California, a California Environmental Laboratory Accreditation Program (ELAP)-certified laboratory under strict chain-of-custody procedures. 3.4 Temporary Sampling Well and Groundwater Sampling At the completion of drilling, soil boring SB18 was converted into a temporary sampling well for the collection of one grab groundwater sample. The temporary well was constructed using two 5-foot sections of 1-inch diameter, 0.010-inch machine-slotted poly-vinyl chloride (PVC) well screen with a threaded bottom cap for the bottom 10 feet and 1-inch diameter, threaded, flush-joint PVC riser pipe to the surface. Facilities I Environmental I Geotechnical I Materials 8