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' tank A process schematic of the system is shown on Figure 3 The anticipated flow � P rate through the system is a maximum of 10 gpm, based on the results of slug tests This flow rate will be monitored and adjusted as necessary throughout the duration of the remediation ' Trace concentrations of petroleum hydrocarbons have been detected in MW-09 dunng quarterly monitonng events Although MW-09 is outside the extraction well ' capture radius, the existing microbial population will biodegrade any residual contaminants near this well. MW-09 will be monitored during the remediation and ' verification periods 2.3 Bench Scale Test ' Prior to start-up of the bioremediation system, a bench-scale test will be performed to determine the quantity of nitrogen introduced into the system by the bioremediation process To ensure complete remediation of the groundwater and residual contaminants in the saturated zone soils, the bioremediation system will ' include the re-injection of treated water into the aquifer The addition of enzymes and amino acids will enhance biodegradation but may also increase the concentrations of mtrogen in the groundwater, especially in the form of ammonia The bench-scale test will allow quantification of the nitrogen produced by a given quantity of enzyme Nitrogen is present in the groundwater onsite in very low concentrations Analyses of a groundwater sample from an upgradient well (MW-02) indicated the following concentrations of nitrogen non-detect for total Kjeldahl nitrogen (TKN), 0 2 milligrams per liter (mg/1)ammonia, 0 04 mg/l nitrate, and non-detect for nitrite The laboratory report is included in Appendix E These concentrations will serve as background levels for the site If the bench-scale test determines that the enzymes will contribute significant amounts of nitrogen to the groundwater, a nitrogen removal system will be installed The nitrogen removal system will have a sampling port in the exit line and bypass piping to recirculate water with concentrations higher than background back through the removal system The specific type of removal system will depend upon the nitrogen species being produced and may include reverse osmosis, filtration, or ' peroxidation The system will be designed to remove nitrogen to background levels Samples will be collected from the exit port of the mixing tank during the ' bioremediation (and the exit port of nitrogen removal system, if nitrogen removal is 94R8 East Bay Municipal Utility District 40429601 rap 10 Remedial Action Plan