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011 0 Former Countryside Market, Stockton,California Feasibility Study and Interim Remedial Action Plan May 20,2013 by the collection of background data. Each AS well will be tested individually at various injection rates followed by testing both injection wells simultaneously with primary observa ion points OBS-1 and MW-2 being monitored for target parameters during all of tests along with the collection of influence data from these wells and secondary observation points MW-1, MW-3, MW-4 and MW-5. Sparging is expected to increase dissolved oxygen (DO) concentrationE to levels that will promote aerobic biodegradation and achieve significant petroleum-hydrocarbon reductions in groundwater and saturated soil. Sparge testing will be completed using air to test the fea ibility of gas delivery to the subsurface. However, the final remedial alternative may include oxygen lsparging to further enhance biodegradation in the subsurface. The results of the sparge test can also be used to design an oxygen sparging system as it has been shown that oxygen flow in the subsurface is similar to air flow, including depth to water(DTW), pressure, PID and DO/oxidation-reduction potential (ORP) readings. Completion of the sparge testing will include groundwater well gauging, grc undwater sampling (pre- and post-test samples), vapor sampling (pre- during-, and post-test samples), PID measurements, and test measurements of air injection pressures, flow rates, vadose pressure, water levels, DO and ORP measurements to evaluate whether the Site is amenable to sparging and if VOCs are stripped from the groundwater. 5.1.5 Sparge Test and Monitoring Equipment The following sparge test equipment will likely be installed near each i jection point for the test: air compressor, desiccant dryer (used to remove oil/water), oil/water coalescing filter, pressure regulator, valves, pressure gauges, temperature gauge, air hose, and Dwyer® Ser'es VF Visi-Float® scfm flow meters. Each injection well head will be fitted with a ball valve, as wells pressure and temperature gauges. A 1-inch flexible compressed air hose equipped with a pressure�egulator, ball valve, and flow meter will lead from the compressor to the sparge wells. A portable, con4truction-rated air compressor will likely be used for testing. Monitoring equipment during the testing will likely include modified well caps with sample ports, In-Situ, Inc. Troll® 9500 multi probe data loggers (or equivalent), a YSI Model 58 or Horiba U22XD field DO sensor, a Rae Systems Mini-Rae 2000 PID, a 200-foot water level meter, and magnehelic pressure/vacuum gauges of differing ranges. 5.1.6 Breakthrough and Step Testing After conducting pre-test sampling and monitoring/shakedown of the equipment, sparge testing will commence by initiating air flow into the injection wells. Injection air pressure will be increased incrementally at an approximate rate of 2 psi per minute to determine the breakthrough pressure required to induce air flow into the injection wells. Flow rate versus pressure s ep testing will be performed immediately after breakthrough is established. The injection airflow wil be manually increased and associated injection pressure increases will be measured. Feasibility Study and lFeasibiliy Study BlW Text Final.dw 5-5 The Source Group,Inc.