Laserfiche WebLink
Passive Systems <br /> Passive systems rely on wind-driven turbines to promote flow of landfill gases to the <br /> atmosphere. Depending on local air quality regulations, gases are either filtered or <br /> discharged directly to the atmosphere. Reduction of landfill gas within the landfill wastes <br /> adjacent to the release area is often effective at minimizing the vertical migration of landfill <br /> gas to groundwater beneath the wastes, thereby reducing the potential for migration in the <br /> aquifer. <br /> An enhanced gas venting system would minimize offsite gas migration and maximize the <br /> volume of landfill gas discharged to the atmosphere (or through a filter system) using a <br /> network of gas wells. <br /> Active Systems <br /> An active gas system typically relies on a series of vertical gas wells to collect gases from <br /> wastes. A vacuum is induced by a powered-blower, and the gas wells are usually connected <br /> . together in a "header" system. The collected gases are typically either flared or used to <br /> generate power in a co-generation plant. The CHSL has a flare system that has sufficient <br /> capacity to accept additional landfill gas. The design basis for landfill gas control system <br /> enhancements assumes that this system will tie into the existing landfill gas control system. <br /> The primary advantage of an active LFG collection system is that it can change the pressure <br /> gradients within the refuse, thus causing LFG to flow into the collection system rather than <br /> into contact with groundwater. <br /> As previously noted, an active LFG collection system has been installed at the CHSL (Figure <br /> 6). Inspection of the spacing of the original landfill gas collection system indicates an <br /> average gas extraction well density of about one well per acre, with wells distributed <br /> relatively evenly throughout the waste prism. Additional LFG wells were installed in refuse <br /> near the northeastern corner of the landfill, but not in the recently-discovered refuse in <br /> Caltrans property. <br /> Enhancement of the gas collection system would focus on installing wells in the 1.3-acre <br /> segment of waste that is outside the current closure limit. Additional landfill gas extraction <br /> in this area of the site could reduce the VOC load in the waste, and reduce the migration <br /> potential to groundwater. <br /> Engineering Feasibility Study Geo-Logic Page ■ 10 <br /> Corral Hollow Sanitary Landfill <br /> wssocIwrEs <br /> January 25,2013 <br />