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GeologicaC4echnid Inc. Page 4 Pilot Test Report COE-Arco Project No, 750.2 August 8,2000 �r 3.1.2 Procedure On June 12, 2000, GTI performed the pilot soil vapor extraction test by extracting air from VEW-1, VEW-2, VEW-3 & VEW-4. Ms Duncan of the SJC PHS/EHD was present for part of the pilot test. '-' While the blower was in operation, performance parameters were measured which included: vacuum pressure, volumetric airflow, and OVM readings. Vacuum readings were measured and recorded at nearby groundwater monitoring wells (MW-1, MW-2 and MW-3) as well as .,. the vapor extraction wells that were not being used for extraction. This information is summarized in Table 2 of Appendix A. A sample of the influent air emissions from each well was collected for analysis from each vapor well approximately two hours after being hooked up to the IC. Two samples were collected from VEW-1 when it was first hooked up to the IC and two hours later to observe changes in concentration over time. A sample was also collected of the effluent from the exhaust pipe of the IC. The air samples were collected in one-liter capacity Tedlar bags and transported by overnight courier to Air Toxics LTD. in Folsom, CA for prompt analysis. i„ 3.1.3 Data Collection The methods and procedures used for collecting the performance data are as follows: Vacuum Drawdown The vacuum response to vapor extraction was measured using Dywer Magnahelic differential pressure gauges by first attaching an air tight cap to the well top. The cap has an orifice, which accepts the vacuum hose from the gauge. The gauges were checked and the values recorded every 0.5 to 1 hour. These readings are summarized in Table 2, Appendix A. Note: the units of vacuum readings given in Table 2 are in inches of water. Pederson 1991 indicates that observation wells showing a vacuum pressure reading of at least `-' 0.1 inches water column are considered to be within the vacuum extraction well's radius of influence. +� Volumetric Air flow To measure the volumetric airflow, a"hot-wire" anemometer was used in a straight section of 2-inch (i.d.) PVC pipe attached to the top of the vapor extraction well. Flow readings in feet per minute (FPM) were made right off the instrument at one-half to one-hour intervals. The airflow was observed to surge throughout the test period. This was most likely caused by the extremely high levels of hydrocarbons and low levels of oxygen in the influent vapor stream causing the IC to constantly adjust supplemental fuel and atmospheric air in order to operate properly. ... The maximum airflow was obtained from VEW-2, 2,100 FPM, equal to 45.8 CFM. The other vapor wells ranged from 1,250 1,900 FPM (27.3 — 41.4 CFM). VEW-4 showed very low flow rates when it was first started, but flow rates increased to levels observed in the �. other wells. The wells were capable of producing higher flows, however due to the low oxygen concentration in the subsurface, the IC could not effectively control the emissions at higher flow rates. v