Like most municipal services, solid waste management has come under increased regulation in recent years in an effort to prevent ground water and surface water contamination. Many of us remember the old city "dump" as a place where garbage was simply pushed into a hollow at the edge of town. Today, landfills are highly engineered systems requiring sophisticated support facilities.

The City of Chattanooga Landfill on Birchwood Pike incorporates multi-layer liners, leachate pumping facilities, a gas collection system, a wheel wash station, and other elements designed by CTI to protect the environment in and around the landfill.

The liner system includes 2 feet of compacted clay achieving a hydraulic conductivity of 1.0 X 10-6 cm/sec. All of the soil material used for this liner was obtained from the site, but had to be screened to remove rocks. Above the clay liner is a bentonite geocomposite layer with a 60-mil high-density polyethylene sheet membrane. The polyethylene sheet is cushioned by a filter fabric under a 12-inch drainage layer of river rock.

In addition to the lining, CTI provided general civil design services for various support facilities, including roadways, administration building, scale house, maintenance building, personnel building, wheel wash facility, and leachate collection facilities.

Due to the topography, two sets of 500-gpm pumps are used to lift leachate from collection trenches into a 430,000-gallon storage tank. The storage tank then discharges to a low-pressure pipeline which conveys leach- ate directly to the Chattanooga Regional Wastewater System.

An integral part of a modern landfill is the gas collection system. At the Birchwood facility, gas is collected from wells and burned in a state-of-the-art flare system.

CTI also designed a privately owned construction and demolition (C&D) landfill adjacent to the landfill. This 15-acre landfill is located on a 53-acre tract and shares the city's entrance road, scale house, and wheel wash facilities. The C&D landfill provides a site where the City can dispose of material that does not require placement in a lined facility.

At this time, CTI is providing permitting assistance to the City of Chattanooga to develop a 50-acre facility to the south of the existing