5.2.-5.4. PCSR 09-13-2011 - Laserfiche WebLink

Home Browse Search

Rebecca Haug City of Elk River August 18, 2011 Page 2 Response: The ERL has modified the final cover drainage design to incorporate the drainage terrace at the break in grade on the top of the west slope. The proposed downslope structure, erosion control matting, and intermediate drainage control pipes have also been modified to incorporate the revisions. A copy of the final cover drainage design is attached as Attachment 2. 3. Temporary final cover is proposed as an element of the September 2008 "Leachate Recirculation Permit Application "proposal. The plans need to be revised to identify the criteria for when an area would receive temporary final cover indicating the maximum length of time. of inactive fill operations. Similarly, the maximum area allowed for inactive fill areas prior to placing temporary final cover needs to be on the plans. Response: Temporary cover systems have been tried over time to address many different elements of landfill operations. Currently, the systems that have been tried have not proven to be sustainable. As new ideas are introduced some are tried in pilot type programs to verify their sustainability. The ERL commits to continue to respond to new technology in regard to temporary cover system as they realize how important this is not only to their operation, but to the surrounding residents of Elk River, as well. There will be continued attempts to identify other sustainable system in the future. As systems are evaluated the performance of them will be summarized in the annual reports that are prepared and submitted to the City. 4. Gas Probe Monitoring and Anal Significant positive pressure readings for gas probes have been indicated over the past several years. This condition may indicate landfill gas migration beyond the waste boundaries. In order to fully evaluate this situation, the landfill must collect and report gas concentration and pressure for each probe for each monitoring event. The landfill must also collect temperature and barometric pressure for the site at the time of the monitoring event and the preceding three days before the monitoring event. All gas probe monitoring data must be fully evaluated in the annual operating report. Response: Although the US EPA and MPCA do not require pressure readings on gas probes and gas probes are subject to atmospheric conditions, thereby limiting the viability of pressure data, the ERL will collect the pressure readings at the probes using appropriate sampling techniques if methane is present in the probes. Thus information will be collected, if applicable, for one license period. Results will be reported and evaluated in the applicable annual report. The requested temperature and barometric pressure data will be provided from the on-site weather station for several hours prior to the monitoring event on the day of the event and results will be provided in the Annual Report. 5. Ambient Air Monitoring The current air monitoring for landfill gas emissions field survey is only conducted for the topslope area accounts for roughly 20 percent of the fill area. There is a higher likelihood that emissions will occur on the sideslope based on the horizontal stratification of the waste and preferred movement of landfill gas. ERL must modify the area of traverse to include all sideslope and topslope areas for ambient air monitoring events. The safety concern for vehicles on landfill sideslopes can be mitigated by traverse on foot with the survey instrument. T:\07420 406Uune11 CByApp\Comment response\Response_0818111LRH_080411 MtgResponse_081811.docx