ARCHIVED REPORTS XR0009663 - Laserfiche WebLink

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i ' approved 55 gallon drums or underlain and covered with 6 mil plastic sheeting and stored on site until their proper disposition can be arranged. Soil samples will be collected for geological and analytical evaluation at five foot intervals. Soil samples will be collected in 5.0 inch brass liners using a 2.0 inch modified California split spoon sampler. All soil samples will be sealed with aluminum foil,capped,labeled and placed in a cooler at 4°Celsius for transport to the laboratory following Chain of Custody protocol. I ' Because every soil sample collected will not be submitted for laboratory analysis,a screening process will be used to gather additional information through field observation noting sediment type,especially grain size and clay content;moisture content;visible evidence of contamination,i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants,and the readings above background on a organic vapor meter(OVM). The OVM is a field portable photo ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential ! ' below 10.0 eV(hydrocarbon range). The soil borings will be closed as follows:after the last soil sample has been collected the augers will be lifted 3 feet and 50 pounds of bentonite will be poured through the hollow stem of the augers and hydrated with clean tap water. A tremie pipe of sufficient length to reach the total depth of the boring will be installed through the center of the hollow stem augers and then the augers will be ' withdrawn from the hole. The borehole annulus will be closed by pumping a neat cement grout (<4%bentonite/cement)through the tremie tube up to grade. ' 2.9 Soil Sampling and Analyses All soil samples will be screened using field methods by observing discoloration and organic vapor ' meter reading. Up to three soil samples from each boring, to include one from the capillary fringe(if appropriate), will be submitted to Sherwood Laboratories of Hilmar(State Certified Laboratory#1400) for benzene,toluene,ethylbenzene and xylene(BTEX by method EPA 8020),and gasoline range petroleum hydrocarbons analyses(TPH-Gasoline). The detection limits for the BTEX analysis is 3.0 pg/kg and 0.5 mg/kg for TPH-Gasoline. A Chain of Custody will be completed for all samples collected and tracked to ensure sample integrity. 2.10 Monitoring Well Construction ' The monitoring wells will be constructed with 2.0 inch diameter,schedule 40 PVC casing with flush threaded joints. A screened interval will consist of 0.020 inch perforations extending from approximately 10 feet below and 10 feet above the water table. ' A number three sand will be used to form a filter pack about the saturated zone(0.020")perforations and will extend two feet above this screened interval. An annular seal will be constructed by ' installing 100 pounds of granular bentonite that will be hydrated with tap water and be allowed to expand for a period of one hour. In the remaining annulus,neat cement grout will be installed using a slurry pump and tremie pipe. ' The well will be secured with a water tight locking cap encased within a traffic safe well box. A well construction schematic is attached as Figure 2. ' Relative well collar elevations may be surveyed by a competent surveyor. 2.11 Monitoring Well Development