LBG Receives AAEE National Grand Award for Innovative Green Leachate Treatment Process05/26/2012
Leggette, Brashears & Graham, Inc. (LBG), has received the Grand Prize from the American Academy for Environmental Engineers (AAEE), as part of the organization’s 2012 Environmental Excellence Awards competition. The firm was honored for its utilization of an innovative landfill leachate treatment process that employed phytoremediation, a truly “green” technology.
LBG was retained by Republic Services, Inc. (Republic) to solve a complicated leachate disposal problem at a Gulf Coast Area landfill (GCAL). An unavoidable change in site conditions caused leachate production to increase an order of magnitude from 350,000 to 3.5 million gallons/year. Reducing leachate production was not an option. The production spike and skyrocketing costs resulted in an immediate ‘high-priority’ status. LBG was tasked with developing a more financially favorable and environmentally friendly method of leachate disposal and a novel approach using phytoremediation was recommended.
Phytoremediation is a plant-based system used to remove pollutants from
groundwater, surface water, soil, or air. Specifically, LBG recommended phytoremediation using a unique grass called vetiver. Vetiver has been in the US for decades, but has never been used to address leachate problems, making the project a first-of-its kind for the US solid waste industry. Vetiver is ideally suited for leachate utilization due to its tremendous water and nutrient demand, fast growth, and extraordinary tolerance to extreme environmental conditions (contaminants, pH, soil, moisture, insects, and disease). Vetiver is also a USDA non-invasive plant. Coincidentally, leachate’s main components are water and contaminants (micro and macro-nutrients to the plants), exactly what vetiver needs.
The role of LBG in this innovative environmental project was to develop and implement the entire phytoremediation concept from start to finish, including: designing the leachate pre-treatment and main distribution system, designing the specialty subsurface-drip irrigation system, developing the PLC control program, assisting in obtaining regulatory approval, procuring all equipment and specialty subcontractor services, overseeing system installation, and operating and maintaining the system upon startup.
The use of phytoremediation at landfills illustrates how an integrated approach to leachate disposal can have a profound environmental impact by protecting groundwater, surface water, soil and air. Groundwater is protected by reducing the likelihood of contaminated leachate migrating from the landfill. Surface water is protected by the prevention and mitigation of leachate seeps (leachate that flows out the side of a landfill and to surface water). Vetiver also removes sediment and nutrients from surface water runoff. Soil erosion is reduced and due to the ability of vetiver to utilize compounds in leachate as nutrients, soil quality is preserved. Air emissions are greatly reduced by eliminating hundreds of thousands of miles driven by diesel-burning tanker trucks that otherwise would have hauled the leachate, and also by the large carbon fixation capacity of fast-growing vetiver.
The GCAL project has exceeded Republic’s expectations. The system has performed as designed and nearly 100% of leachate generated has been utilized on site, well ahead of anticipated results. Phytoremediation system low-cost operations and maintenance has cut annual costs by 60%, saving millions over a standard 30-year post-closure care period.
In all, a very robust and self-adjusting system was installed in a compressed timeframe,overcoming numerous complex issues and resulting in a host of benefits, including: substantial long-term financial savings, easy maintenance, a new alternative for engineers to consider for leachate disposal, advancement of regulatory acceptance, lessening the impact of landfills on the surrounding community, aesthetic enhancements for surrounding neighbors, habitat for wildlife, carbon footprint reductions, protection of groundwater, surface water, soil and air resources, and reduced loading to WWTPs.