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Design and Operations Plan October 24, 2011 <br />Western Gravel E & P Waste Disposal Facility Page 40 of 51 <br />soils, odiferous liquid, petroleum sheen and/or unusual color). In the event that a seep is observed, activities <br />will be conducted in accordance with the contingency plan presented in Section 4.7.3. <br />Seep monitoring documentation shall be maintained in the Operating Record. A seep monitoring report will <br />be prepared annually and submitted to CDPHE. The report will include a discussion of monitoring activities <br />and evaluation of analytical results if samples are collected. <br />3.12 STORMWATER RETENTION POND MONITORING <br />Environmental monitoring of each retention pond (basin) used to collect run -off stormwater will include <br />visual and sample analytical result assessments. Visual inspections will be conducted by landfill personnel <br />on a quarterly basis and analytical samples collected annually, if possible. In addition, a registered Colorado <br />engineer shall conduct an annual inspection. Visual assessments shall help identify maintenance needs and <br />ascertain that facility components are operating as designed and intended. Water collected in the retention <br />basin will be sampled annually if possible and analyzed for informational purposes. At a minimum, analysis <br />will include sodium, chloride, and BTEX. Additional details are provided in the contingency plan presented <br />in Section 4.7.4. <br />Analytical results and the engineer's inspection findings will be provided to CDPHE in an annual monitoring <br />report. Quarterly inspection reports and the annual report will be placed in the facility Operating Record. <br />3.13 LANDFILL GAS MONITORING <br />Landfill gases at the facility will likely be methane and VOCs. Any produced methane is anticipated to <br />occur through decomposition of soil amendment materials (e.g. wood chips) and VOCs inherent in disposed <br />petroleum impacted materials (e.g. drill cuttings and mud, PCS). Because of the nature of material proposed <br />for disposal, arid climate, and minimal anticipated leachate generation, landfill gas (LFG) production is <br />anticipated to be very slow and at low volumes. Therefore, explosive gas at the facility is not expected to be <br />problematic. In accordance with solid waste facility regulations, quarterly LFG monitoring will be <br />conducted at the working face, throughout landfill cells, and any wet/dry wells. However, it is recommended <br />to conduct air monitoring within active cell areas more frequently during busier periods mainly for personnel <br />and public health reasons because of VOCs anticipated to be present in disposed waste. In the event that <br />methane and/or VOC levels are measured at elevated levels, activities will be conducted in accordance with <br />the contingency plan presented in Section 4.8.5. <br />LFG monitoring for methane and VOCs shall be conducted using an industry appropriate gas monitoring <br />device (e.g. photoionization detector, multiple gas detector, LandGEMTM). Monitoring equipment shall be <br />maintained, calibrated, and used in accordance with manufacture instructions. LFG monitoring results shall <br />be maintained in the Operating Record and included in the annual monitoring report to be submitted to <br />CDPHE. <br />NWCC, Inc. <br />