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' Corrective Action Plan Montgomery Ward Auto Service Center, Stockton, CA ' - Flow rate of 200 to 300 scfin 10- to 12-inch mercury vacuum rating Air-Sparging System A limited amount of testing was performed during the pilot testing at the Montgomery Ward Site to evaluate air sparging Basically, air sparging was implemented in one well (VEW-1B) for a period of about four hours During the first two hours, air sparging was implemented on a pulsed mode, i e , it was on for a short period (1 to 2 minutes) and off for the same period After the first two hours, continuous air sparging was performed for two hours Approximately 5 scfm of air at 30 psi of pressure was infected into the bottom ' of the well through a flexible tube A packer was installed above the injection point between the well casing and air infection tubing to prevent the sparged air from traveling back into the well only During the air sparging test, EAI monitored the following parameters 1) vapor concentration in the surrounding wells and soil vapor probes, 2) dissolved oxygen level in the surrounding ground water monitoring wells and air sparging monitoring wells The ' results show that limited influence of air sparging can be interpreted to exist It appears that the vapor concentration and dissolved oxygen levels in adjacent wells (VEW-3, VEW- 4 and VEW-5) increased after sparging was started This would support the following conclusions ■ 5 scfm at 30 psi is appropriate for air sparging at this location Radius of influence of the air sparging is probably around 20 to 30 feet around VEW-1B 8.3 System Components Existing Vapor Extraction/Combination/Air Sparging Wells ' The locations of all existing wells associated with the Montgomery Ward Site are shown in Figure 12 Construction details for all existing wells are summarized on Table 9 and provided in Appendix B Well VEW-1 was designed to be located at the center of the ' impacted soil plume near B-11 Well VEW-1 consists of a dual well configuration (VEW- lA and VEW-1B) VEW-1A is screened between a depth of 10 and 25 feet bgs while VEW-1B is screened between 25 and 40 feet bgs This dual-well completion will allow targeting specific depth intervals of the soil plume in this area Well VEW-2 is screened from 15 to 35 feet bgs Well VEW-2B is screened between 35 to 50 feet bgs This dual-well completion will allow targeting specific depth intervals of the soil plume in anis area Wells VEW-3, VEW-4 and VEW-5 all have screens for vapor extracting at depths of 20 to ' 30 feet bgs „ being .] nvrrnnt,nn cx,ell [IP11 VFW-1B .- also screened in dLLLLltloil to llGlilg useu as a `vapor 1.A�L[AV 41V11 , ' between 64 and 65 feet bgs (which is about 20 feet below the ground water table) so that the well can be used as an air sparging well A 64 foot long, 1-inch PVC pipe assembly was constructed with a packer at the bottom and blank casing above the packer A 3/8- Project No 1232 - 22 - SAB 22 -SAB WOR➢1232CAP