1Landfill Leachate Disposal with Irrigated Vetiver Grass

Abstract: Stotts Creek Landfill is a major waste depot of the Tweed Shire receiving wastes from both Tweed Heads and Murwillumbah townships and neighboring local government areas. Disposal of leachate is a major concern of the Shire as the landfill site is close to agricultural areas. An effective and low cost leachate disposal system is needed, particularly during summer high rainfall season. As vetiver grass has a very high water use and nutrient uptake rates, and it is tolerant to elevated levels of heavy metals and other adverse conditions, it is best suited for effluent and leachate disposal. Leachate quality at Stotts Creek Landfill is low in heavy metals but relatively high in salts and nutrients. Currently leachate and runoff from the landfill site are stored in ponds at the foot of the mound. During dry periods the leachate is irrigated onto the top of the completed waste mound where it evaporates or transpires into the atmosphere. During heavy rainfall the leachate overflows into a system of wetlands and then to a local creek. Following capping and topsoiling, vetiver has been planted on the surface of the completed waste mound and irrigated with leachate from collecting ponds. An area of 3.5ha has been planted with vetiver in January 2003 and was increased to about 6ha in total late in 2004. Results to date have been excellent, in the second year thick and tall, 3m high, vetiver growth was recorded. The growth was so vigorous that during the dry period, there was not enough leachate in the ponds to irrigate both the old and new plantings