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North County Sanitary Landfi -2- 19 June 2017 San Joaquin County Monitoring Well Installation Work Plan The Discharger proposes to install one groundwater monitoring well (G-9) as a POC well located west-northwest of Areas 5 and 6 expansion areas. This well is being installed to comply with Title 27, section 20405 and the WDRs. Staff has reviewed the Work Plan and the proposed scope of work. Well G-9 will be installed in a similar fashion However, the Work Plan submitted for the installation of well G-9 does not address the landfill's groundwater wells that make up the monitoring system. Following review of the Annual 2016 Monitoring Report for the NCSL, low groundwater levels noted in the NOV continue to persist throughout the 2016 monitoring year. Due to low water levels, wells G-1A, G-3, G-4, and G-6 could not yield groundwater samples during 2016. Due to the lack groundwater samples collected, the Discharger's DMP for the NCSL remains out of compliance. On 26 May 2017, a teleconference with staff and the Discharger was conducted to discuss concerns with the Work Plan and the lack of response to the NOV. Staff expressed the following concerns listed below. • Wells G-7 and G-8 were installed with screens that were set below the water table. The Discharger explained the encountered stratum was dry to a depth of 220 feet below ground surface (bgs) and that during drilling, particular attention was paid to the depth of first encountered groundwater. However, the finished groundwater monitoring wells were constructed with screens below the top of the water table. (Staff comment: Wells with 20 to 30 feet of groundwater above the top of screens is an unfavorable condition that does not meet the intent of Title 27 or the DMP and staff is concerned about collecting representative groundwater samples). • Well G-9 will be drilled similar to wells G-7 and G-8. (Staff comment: Since G-7 and G-8 were constructed in a manner that does not meet the intent of Title 27 or the DMP, staff is concerned the installation of G-9 in a similar fashion will create a third well with screens set below the water table. The Discharger shall make every effort to construct the well with the screen intersecting the water table. This effort may include consideration of other drilling methods that may better define the interface between the unsaturated and saturated zone). • Wells G-1A and G-6 did not yield groundwater samples during 2016, (See below) and, • The Work Plan did not address the deficiencies of the DMP by proposing to deepen wells G-1A and G-6. (Staff comment: Dry wells do not meet the intent of the DMP and the continued condition is evidence the wells need to be deepened or new wells installed. The NOV issued required these wells to be deepened unless the condition changed. The condition in the wells has not changed and the Discharger shall comply with Title 27 and correct the deficient DMP). Summary As a result of the teleconference, staff made it clear to the Discharger of the concerns stated above. Staff agreed to allow the Discharger to submit the First Semi-Annual Report prior to requiring reconditioning wells G-1A and G-6. Once the report is submitted, staff will review the groundwater data and evaluate whether groundwater levels in these wells have changed to where groundwater samples can be properly collected. If groundwater samples cannot be