![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Landfill Gas Consumption in Rhizosphere of Alternative Landfill Covers
The two identical 12 ft by 12 ft by 12 ft, polished stainless steel, insulated Environmental Chambers, located within the Testing and Evaluation (T&E) Facility, incorporate unique design features. Each chamber is equipped with 16 light fixtures containing a total of 32 light bulbs; one metal halide and one sodium vapor bulb in each fixture cover the photosynthetically active radiation (PAR) portion of sunlight spectrum (wavelengths between 400 nm and 700 nm). The chamber system is equipped with a powerful heating, ventilation, and air conditioning (HVAC) system that includes a 10-ton chiller, electric heater, and humidifier. The combination of the light and HVAC system is capable of simulating outdoor environments and seasonal variations including day and night cycles, adjustable temperatures between 450F and 1000F, humidity control, and variable air flow rates to simulate wind effects. The operating conditions and parameters of the Environmental Chambers are controlled by a computerized control system that can monitor and control temperature, humidity, air flow rate, and light intensity. Features of the control system include continuous data logging, trend graphs, and system alarms. The control system is housed in the control room adjacent to the chambers. Four 100-gallon stainless steel tanks, 35-inch diameter by 34-inch tall, are located in the chamber. A gas distribution diffuser placed within a 4-inch layer of gravel at the bottom of the tank, feeds methane (93 percent industrial grade) from a cylinder located outside the chamber to the soil via copper tubing. A manual control valve and rotometer, located at the cylinder, are used to control the flow of methane into the tank. Felt is placed above the gravel to prevent soil from entering the gravel layer and to aid in dispersing the gas. Gas samples are collected from 2 slotted PVC pipes positioned vertically at different depths within the soil and from a static chamber positioned directly on the soil surface to measure methane leaving the simulated cover. Ambient air samples are collected above the tank. Samples are analyzed by direct injection of a GC/FID located in the adjacent control room.
Contact: Steven Rock, USEPA (EIMS#76703)