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Treatability Study Report and Feasibility Evaluation for In Situ Petroleum Hydrocarbon Remediation Field Maintenance Shop #24, 8020 South Airport Way Stockton, California 4.0 AIR SPARGE TREATABILITY TEST 4.1. EQUIPMENT INSTALLATION Pilot test equipment installed at the site for the air sparge test included an air compressor, desiccant dryer (used to remove oil/water), oil/water coalescing filter, pressure regulator, valves, pressure gauges, temperature gauge, air hose, and Dwyer° Series VF Visi-Float° rotameters with flow ranges between 0 to 40 and 0 to 50 scfm. Equipment also included tanks of compressed helium, a pressure regulator, and a Dwyer° Series VF Visi-Float° rotameter used for helium tracer gas injection. The air compressor used for the test was a 49 horsepower, diesel powered, trailer -mounted unit rated at 160 cubic feet per minute (cfm) at 100 pounds per square inch gauge (psig). The line leading from the compressor to the AS wells was a 50 -foot length of 1 -inch flexible compressed air hose. The helium hose was connected to the air sparge manifold upstream of the air sparge flow meter. Monitoring equipment used during the test included four In Situ, Inc. Troll® 9500 transducers fitted with Rugged Dissolved Oxygen probes, a MiniRae® 2000 PID calibrated with 100 ppmv isobutylene calibration gas, a GasTecho GT -408 multi -gas meter calibrated with 2.5% methane (by volume) calibration gas, a Radiodete° ction MGD -2002 helium detector, a 100 -foot water level meter, and Dwyer° Magnehelic pressure/vacuum gauges with various measurement ranges. Prior to conducting air sparge testing, the Troll® 9500 multi -parameter groundwater quality monitor including an optical dissolved oxygen probes 1.5 feet off the bottoms of wells FMS-MW1, FMS-MW5, FMS-DPE1, and FMS-DPE2. The transducers were used to record water level (measured as feet of water column above the sensor) and dissolved oxygen (milligrams per liter [mg/L]) at 30 -second intervals before, during, and after air sparge testing. Wells FMS-MW1, FMS-MW2, FMS-MW4, FMS-MW5, FMS-DPE1, FMS-DPE2, and FMS-SVE1 were fitted with PVC slip caps with sample ports for monitoring induced pressures and field sample collection. 4.2. TESTING PROCEDURES After conducting pre-test sampling/monitoring and shakedown of the equipment, pilot testing was started by initiating air flow into the air sparge well FMS-AS1A (screened from 37 to 39 feet bgs). Sparging at well FMS-AS1 B (screened from 64 to 66 feet bgs) was conducted on the second day of air sparge testing. At each well, injection air pressure was incrementally increased to determine the breakthrough pressure required to induce air flow into the sparge well. Based on initial groundwater elevation and the depth of the AS well screens, the minimum theoretical pressure required to displace the water from the casing is 6.65 feet of water column (2.88 psig) at well FMS-AS1A and 33.59 feet of water column (14.55 psig) (not including pressure required to overcome the formation and sand pack resistance). Breakthrough pressure was observed at approximately 27 psig in well FMS-AS1A and 60 psig in well FMS-AS1 B. Actual breakthrough pressure was greater than the minimum theoretical pressure due to the additional pressure caused by the piping, well slots, annular filter pack, and aquifer/formation properties. Following testing, the caps were briefly removed from wells FMS-DPE1, FMS-DPE2 and FMS-MW5, and the wells were visually inspected for bubbling using a handheld spotlight. Bubbling in the water column of nearby wells is a sign of air sparge influence. OTIE 20