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' George's Service • • Pilot Test Work Plan rTREATMENT SYSTEM PARAMETERS ' In a letter dated September 23, 2014, GZA proposed modifications to the operation and maintenance schedule as well as the monitoring program. The changes were approved by EHD in a letter dated September 26, 2014. • Operation and maintenance has been reduced from a bi-weekly schedule to a monthly schedule. ,'�"o- rl p('�SS o I J+-�I D- Va � ' • Performance monitoring has been reduced from monthly monitoring to quarterly monitoring. Groundwater will be monitored and sampled quarterly for one year to assess the impact of the new wells. After one year the monitoring program will be reduced to semi-annual events. Air Sparging Treatment Ground Zero also proposes a change in the sequence of air sparging. Currently, five of the ' wells in consecutive sequence are between the structure and Durham Ferry Road. GZA believes this could cause excessive mounding in that area. GZA proposes that the sequence ',� be changed to the following order: OS-1, -2, AS-3, AS-1, AS-6, AS-5, and AS-2 for 20 y Y0low ' minutes each followed by a 30 minute delay prior to starting the sequence again. GZA d'r)``- believes this will effectively disperse air into the aquifer while reducing prolongedlAk groundwater mounding. / 7 r Soil Vapor Extraction and Treatment Ground Zero proposes alternating vapor well configuration monthly to deter the creation of ' preferential pathways in the vadose zone. The well configuration changes will be logged on (� the field log book. Monthly Treatment System Performance Monitoring Ground Zero proposes that monthly readings be recorded on the air sparging system. The technician will record pressure readings to the manifold from the compressor as w .1P 1 ac total system operating hours. Pressure, flow, and cycle rimes will be recorded for each AS well. The air manifold will be checked monthly for leaks and repaired as necessary. Air sparging ' wellheads will be inspected quarterly for leaks and repaired as necessary. Semi-annual maintenance will be performed on the compressor. Ground Zero proposes that during the monthly operation and maintenance event, PID gkkr l d readings will be taken and recorded from the influent, intermediate and effluent sample ports l7 c t- of the treatment system. Influent and effluent flow will also be measured and recorded. O)�- Quarterly Treatment System Performance Monitoring C �krn lAjl. ' it sparging per will be monitored quarterly by measuring and recording dissolved_fW 14P ai ox Currently MW-1, MW-2, MW-7, MW-101,temperature, pH, conductivity, and oxidation-reduction potential in selected wells. OW-1 and OW-2 are used to monitor system Ground Zero Analysis,Inc. 2 1