CO0003088 - Laserfiche WebLink

Home Browse Search

SCS ENGINEERS- Landfill History The Corral Hollow Landfill was initially operated as a refuse burn and disposal site beginning in the mid- to late- 1950's. Burning was discontinued in the mid-1970's. Since that time, the facility has been operated as a sanitary landfill for disposal of municipal solid wastes (MSW), including residential and commercial refuse, tires, and construction/demolition wastes. No hazardous wastes are accepted at the landfill. As shown in Figure 2, refuse fill elevations will approach an elevation of approximately 340 ft above mean sea level (MSL) at site closure. Surrounding grades range from elevation 250 to 330 ft MSL along the eastern and western perimeter areas, respectively. Reportedly, the refuse fill extends to depth 215 MSL (35 to 115 ft below surrounding grades). Landfill Closure At current fill rates, the Corral Hollow Landfill will reach permitted capacity in Spring, 1995. A final cover system will be placed in accordance with CCR Title 14 and Subtitle D closure regulations. A final closure plan was submitted to the CIWMB and LEA by the County in January, 1994. Other closure improvements will include removal of existing site structures, construction of drainage facilities, and if necessary, installation of an LFG emissions/migration control system. Closure work is expected to commence in Summer, 1995. 4. PROPOSED PERIMETER LFG MONITORING NETWORK The proposed LFG monitoring system has been designed to account for regulatory guidelines, site-specific characteristics, and potential migration pathways. Monitoring Well Locations A network of seven perimeter LFG monitoring wells is proposed. All wells will be located in native soils outside the landfill, near the property boundary. The proposed locations for these wells, designated GW-1 through GW-7, are shown in Figure 2. Construction Details The wells will generally be installed to either of the following depths: (1) equal to the maximum depth of refuse within 1,000 ft of the monitoring point (215 ft MSL); or (2) subsurface water is encountered. In instances where groundwater is encountered before the boring is advanced to the depth of refuse, drilling will cease and a 5-ft bentonite/soil seal will be installed. In no instance shall a well boring penetrate underlying aquifers. A proposed schedule of well depths is provided in Table 1 . Well borings will be advanced using hollow-stem auger drilling equipment. Two or more gas monitoring probes consisting of 1/2 inch-diameter threaded Schedule 80 PVC will be installed in each well. 4