The Perkins Landfill located in Payne County, Oklahoma is currently closed and in the post closure-monitoring period. Aquaterra developed a work plan for submittal to the Oklahoma Department of Environmental Quality (ODEQ) 
to mitigate leachate seeps at the facility. The work plan included installing passive landfill gas (LFG) vents and planting vetiver grass within the leachate seep areas. The work plan was approved and implementation began in 2011.
Passive LFG Vents
Aquaterra provided oversight during the installation of 16 passive LFG vents. The passive LFG vents were installed using a 36-inch bucket auger on a track-mounted rig and 
were constructed of 6-inch diameter SDR 11 HDPE pipe and 1 to 3-inch diameter washed gravel.
Vetiver Grass Planting
Aquaterra personnel planted various plots of vetiver grass in rows at the locations of existing and previous leachate seeps. The grass was planted with a 2-foot spacing between each plant and row. Vetiver grass is native to Asia and has been used worldwide for various reasons, including soil stabilization, wastewater treatment, and leachate mitigation. The variety used for this application is USDA approved as a non-invasive plant because it produces an infertile, sterile seed. Vetiver grass can tolerate: temperatures from 5 to 115 °F; pH ranges from 3 to 10; very high salinity; high metals concentrations; agricultural chemicals; high nitrogen levels; high phosphorous levels; wide range of soil types; and planting on steep slopes. Vetiver grass typically grows to a height of 5 to 10 feet, with a root depth equal to or greater than the plant height. Vetiver grass is native to warm climates and its endurance in this region is unknown. The plant is tolerant to periods of freezing weather, but it is unknown how much cold weather it can tolerate. The Aquaterra plots will determine the effectiveness and practicality of utilizing vetiver grass for mitigation of leachate seeps in this region.
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