ARCHIVED REPORTS_XR0003098 - Laserfiche WebLink

Home Browse Search

4_4 Remedial!Actions ' 4.4.1 Vapor Extraction Well Installations In October 1993, RESNA supervised the dolling of three bonngs which were completed as vapor ' extraction wells VW-1, VW-2 and VW-3 The wells were constructed of 4-inch PVC casing and were screened between 20 and 50 feet below ground surface ' In late 1994, the Clearwater Group, Inc supervised the installation of two additional vapor extraction wells, VW-4 and VW-5 in the vicinity of the former fuel dispenser (Figure 2) Both wells were constructed of 2-inch PVC casing VW4 was screened from 10 to 40 feet and VW-5 was screened ' from 40 to 50 feet below ground surface Locations of vapor extraction wells are shown on Figure 2 Vapor well construction logs are contained in Appendix G ' 4.4.2 Soil Vapor Extraction Test On October 22, 1993, RESNA conducted a one-day sort vapor extraction test (VET) using newly ' installed vapor extraction wells VW-1, VW-2, and VW-3 The vapor extraction test was conducted to obtain data to determine the feasibility of vapor extraction at this site, to determine the effective radius ' of influence, to select the optimum off-gas abatement process, and to develop engineering design criteria for the construction of a soil remediation system at the subject site The test was performed using the following equipment 1) a regenerative blower system with a 5hp motor, in-lune filter, and ambient air dilution valve, 2) a moisture separator for the removal of condensate, 3)a 3-phase generator,4)two 200 pound carbon vessels connected in series, 5) a portable ' PID, and 6) a set of associated piping, control valves, and instrumentation for field measurements and manual adjustment of controls ' Well VW-2 was used as the extraction well for the long term test VW-2 is located between the former tank pit and the pump island Wells VW-1 and VW-3 were used as observation wells RESNA operated the regenerative blower system on VW-2 for approximately two hours, while monitoring the ' change in induced vacuum response at the two observation wells The extraction flow rate held constant at about 100 to 105 actual cubic feet per minute (cfm) at an applied vacuum of 30 inches of water column After the blower operated for 15 minutes, a vapor sample was collected for laboratory 1 analysis A second sample was also collected for laboratory analysis after the blower operated for 90 minutes, as well as an effluent vapor sample from the vapor-phase carbon vessels A portable PID was used to monitor petroleum hydrocarbon vapor concentrations from the extraction well during the ' vapor test and during vapor sampling ' Two short term tests were conducted first using VW-1 and then VW-3 as the vapor extraction well while the remaining two wells were used as observation wells These tests were used to collect additional data to assist in determining the effective radius of influence, and to determine the petroleum hydrocarbon concentrations extracted from these wells The regenerative blower system was operated W\95141\quartlyl4W-1995 doc 6 M • SMTH 1