FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

0 46 Soil Vapor and Groundwater Sampling—Direct-Push Borings Fifteen soil borings will be advance to approximately 20 feet below ground surface (bgs), and eight soil borings will be advanced to approximately 40 feet bgs. The borings will be advanced using a Geoprobe percussion hammer driven sampler equipped with a 2-inch diameter conical bit. A licensed C57 drilling contractor will drill the borings under the supervision of a Condor geologist. For the borings to 20 feet bgs, soil gas samples will be collected at depths of approximately 10 and 20 feet bgs in each boring. For the four borings to 40 feet bgs along the northern site boundary, soil gas samples will be collected at 10 and 20 feet bgs and groundwater samples will also be collected from approximately 40 feet bgs. For the four borings to 40 feet bgs along the eastern site boundary, soil gas samples will be collected at five and 15 feet bgs and groundwater samples will also be collected from approximately 40 feet bgs. Soil gas samples will be collected using an expendable or retractable sampling tip. The soil gas sampling tip will be advanced to the target depth and opened, and a soil gas sample will be collected in a tedlar bag or in a Summa canister using a vacuum pump. Each sample container will be labeled and delivered to a state certified laboratory for analyses. The groundwater sampler utilizes a sealed, water-tight, stainless steel sample chamber and PVC screen which is isolated from the surrounding environment as the sampler is advanced. When the desired depth for collection of a groundwater sample is reached, the sample chamber is opened by pulling back on the body of the sampler and exposing the screen. When the screen is full, a stainless steel bailer is lowered through the rods to collect the groundwater sample. The groundwater will be gently emptied from the bailer into the appropriate laboratory supplied containers. The sample containers will be sealed, labeled, placed in a cooler chilled with ice, and delivered under chain-of-custody procedures to a California certified laboratory for analyses. Prior to use, the sampling equipment will be decontaminated by washing in a solution of laboratory- grade, non-phosphate detergent and deionized water, and double rinsing with deionized water. Following completion of the sampling, the borings will be filled with neat cement. The cement will be tremied into the borehole to avoid bridging. P:3638 CSUS Stockton Campus Elementary School(SUSD)\3638F Pittman School PEA\Sampling Procedurc.doc