Laserfiche WebLink
Treatability Study Report and Feasibility Evaluation for <br />In Situ Petroleum Hydrocarbon Remediation <br />Field Maintenance Shop #24, 8020 South Airport Way <br />Stockton, California <br />3.1.3. Advective Airflow Measurement <br />Near the middle and end of the vacuum ROI test of well FMS-SVE1, OTIE measured advective <br />air flow in the subsurface at select monitoring points. A one -liter Tedlar® bag was filled with air <br />and attached to the sample port at each monitoring point to evaluate advective airflow and to <br />verify that airflow occurred at the monitoring point(s) where induced vacuums were observed. <br />The time required to deflate a Tedlar® bag was recorded and used to calculate the advective <br />airflow rate. <br />3.1.4. Field Measurement of Vapor Concentrations <br />Vapor concentrations in the test and monitoring wells were measured periodically throughout <br />SVE testing. Vapor samples for field analysis were pumped from sample ports into dedicated <br />Tedlar° bags using a Gast® oil -less vacuum pump. The samples were analyzed for VOCs using <br />a MiniRae 2000 photoionization detector (PID) calibrated with 100-ppmv isobutylene calibration <br />gas and a GasTech GT -408 multi -gas meter calibrated with 2.5% by volume [50% lower <br />explosive limit (LEL)] methane calibration gas. The GT -408 meter was also used to measure <br />percent (%) of LEL as methane, and percent oxygen and carbon dioxide by volume. <br />At the start of testing, the GT -408 meter was not functioning properly. The unit was immediately <br />replaced and readings using the meter resumed by 12:00 PM the same day. Additional vapor <br />concentration field measurements were taken using a Horiba organic vapor analyzer (OVA) <br />calibrated with 100-ppmv hexane calibration gas (supplied and operated by CalClean). <br />3.1.5. Vapor Sampling <br />Shortly after initiating extraction from well FMS-SVE1, a Tedlar® bag vapor sample was <br />collected from the extraction system influent for laboratory analysis. A Gast° oil -less vacuum <br />pump was used to collect the sample into a Tedlar® bag from a sample port installed in the <br />extraction piping. A second vapor sample was collected from the system influent shortly before <br />completion of the FMS-SVE1 test. <br />Additional Tedlar° bag vapor samples were collected from the system influent prior to <br />completion of the short SVE tests at wellsFMS-DPE1, FMS-DPE2, and FMS-MW5. <br />Samples were delivered to the analytical laboratory (BC Labs) under proper chain -of -custody <br />and analyzed for TPH-g, VOCs, and fuel oxygenates using U.S. EPA Methods TO -3 and TO -14. <br />3.2. RESULTS <br />3.2.1. Vacuum Vs. Flow Step Test <br />A vacuum versus flow step test was completed at FMS-SVE1 to evaluate the feasibility of soil <br />vapor extraction without extracting groundwater and to aid in future treatment equipment sizing <br />and selection, if applicable. <br />The test was performed at conditions ranging from an initial vacuum of 43 in. w.c. to a final <br />vacuum of 143 in. w.c. with flows ranging from 58 scfm to 86 scfm, respectively. Once vacuum <br />reached approximately 70 in w.c., moisture was visible in the line and vapor extraction began to <br />produce water. Additionally, water was evident in the well as a result of applied vacuum <br />observed from the groundwater transducer. <br />Following the step test, the vacuum and flow were reduced to approximately 25 in. w.c. at a flow <br />of 50 scfm and the system operated approximately 3 hours. Vacuum was adjusted during the <br />CTI E 16 <br />