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Taj Bahadori Page 4of6 December 8, 2017 • Water removed during surging and purging will be a minimum of three times the water volume in the well prior to the start of purging plus three times the volume of water added for purging and surging • Temperature is consistent within 0.2 deg F • Specific conductivity is within 10 percent change • pH varies less than 0.2 pH units • Turbidity varies not more than 10% Well Installation Report A well installation report for G -3E including the analytical results of first monitoring event will be included with the First Semiannual 2018 Monitoring Report. Well Completion Form 188 will be submitted to the California Department of Water Resources. Boring logs, well completion details, and survey data will be uploaded to GeoTracker. The well installation report will include the items listed in the RWQCB's Monitoring Well Installation Report Guidelines. The report will be signed by a California -licensed professional engineer or geologist. Well installation reports for new wells G-113 and G -6A will be submitted following their construction. The first monitoring events for these wells will included the full suite of Constituents of Concern from Table VI of the NCSL's Monitoring and Reporting Program Number R5-2010-0016. Proposed Increase to the LFG Extraction System Methane was detected in soil gas probe SG -6 at approximately 18 percent (%) by volume in air, which is consistent with previous monitoring events. Internal well SG -6 is located adjacent and southeast of landfill modules M1 and M3. This is an indication that the LFG extraction system is not controlling the migration of LFG from the unit, although SG -6 is not one of the Title 27 compliance perimeter monitoring probes at the site, it potentially puts nearby structures at risk. The County believes that fine-tuning the gas collection system by pulling harder on SG -6 and nearby wells might mitigate the situation. The County thus proposes to: 1) Enhance the tuning and monitoring of the existing wells in order to recover more LFG from the waste unit in an effort to decrease the migration using the existing wells, and; 2) Install methane monitors/sensors with audible alarms and LED indicators in the two closest occupiable buildings to monitor for the presence of methane caused by migration of LFG. 3) If the enhanced tuning of the field fails to address the gas migration at SG -6, then, the County proposes to expand the LFG extraction system with the installation of up to two (2) additional extraction wells. The County has installed deep gas collection trenches in the vicinity of SG -6 during module construction and, by connecting these existing trenches to the gas collection system, migration should be adequately controlled. North County 2017 NOV Final 120817.docx