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Former Apache Plastics . 2 - 23 October 2014 2050 East Fremont Street. 2 . In the NOI , you propose using MW-2, MW-8, and MW-18 as transition zone wells and MW-6 and MW-10 as compliance zone wells. The compliance zone wells are over 100 feet from the treatment zone and would require monitoring for a very long time before a groundwater response could be observed at this location . Compliance zone wells should be located at a reasonable distance downgradient of the treatment zone to ensure breakdown products generated or mobilized from the ISCO reactions do not exceed water quality objectives and groundwater limitations . Considering the location of the proposed compliance zone wells and site lithology consisting of silty clay, groundwater constituents from the ISCO reaction potentially may not be observed in the compliance wells for over 10 years . Central Valley Water Board staff is concerned that the proposed compliance zone wells are too far from the Site to provide useful data in determining if water quality objectives and groundwater limitations are exceeded. Central Valley Water Board staff recommends installing new transition zone wells and utilizing the proposed transition zone wells as compliance zone wells. In addition , please provide an estimated groundwater velocity to support the proposed transition and compliance zone well locations. 3. A contingency plan must be included in the NOI that ensures compliance with Section E (Groundwater Limitations) of the General Order. The contingency plan must include constituent concentration trigger levels in compliance zone wells that will require implementation of the contingency plan. According to the General Order, a contingency plan is required to be implemented to correct unacceptable water quality effects from ISCO applications. The contingency plan should describe in detail actions that will be taken to bring any constituents exceeding WOOS and limitations from the ISCO injections back into compliance with the requirements of the General Order. Based on Central Valley Water Board staff's review of your NOI , you are to submit the following: • Determine the groundwater flow velocity and identify or install transition and compliance zones wells that are closer and downgradient of the treatment zone . A work plan will be required to install new wells, including injection wells. Exclude monitoring wells as proposed ISCO injection points, and in an amended NOI and MRP properly identify the wells that will be used to for injection and monitoring of the project. • Include in the amended NOI a contingency plan that describes detailed corrective actions that will be implemented if deleterious by products exceed 20% of background or water quality objectives are observed at the compliance wells. • According to Site reports, other than well VEW-2 there does not appear to be any downgradient monitoring wells screened across the water table interface. Central Valley Water Board staff recommends installing properly screened monitoring wells to monitor