Sioux Falls Regional Sanitary Landfill
The City of Sioux Falls began operating a landfill methane destruction project in April 2006. The project reduces the amount of methane released by the largest landfill in South Dakota. The methane is collected and directed to a flare at the landfill.
The project consists of 90 gas extraction wells, many of which double as leachate collection wells. The landfill gas is separated from the leachate at multiple lift stations, effectively cleaning leachate and condensate from the gas before it is sent to the flare for destruction. Initial testing occurred on April 5 and 6, 2006, and continuous operation of the flare began on April 7, 2006.
The City has also been able to initiate a project whereby the landfill gas is sent via pipeline to an ethanol plant, where it replaces fossil fuels as a source of process heat. The pipeline became operational on February 26, 2009. Most of the landfill gas is now directed to the ethanol plant where it is used constructively to create process heat for ethanol production.
TerraPass funds provide the only financial return from installation of the flaring portion of the gas collection system and help cover the operational costs of the project.
Project details
The Sioux Falls Regional Landfill is a city-owned, active waste disposal facility in Minnehaha County, South Dakota, and serves about 225,000 people. Opened in 1979 as the Runge Landfill, the site has approximately 3.4 million tons of waste-in-place over multiple cells. The initial 160-acre fill area is nearing its design capacity and will close in the next few years. A 160-acre expansion area is already approved and constructed, and will extend the operating life of the landfill about 34 years.
The gas collection and control system consists of 42 gas and leachate collection wells. The first set of 19 wells was installed in October 2005, primarily to collect leachate. An additional 23 wells were added in November 2007. The flare system came online in April 2006, and the active gas collection system has been operating consistently since that time. Landfill gas flow is measured by a flow meter.
Sioux Falls’ gas emissions are well below any regulatory threshold for mandatory control. Interestingly, a geohazard study undertaken in the early 1980’s showed that the landfill area was built on a significantly thick layer of glacial till. The clayey substrate effectively blocks seepage, as the surveying crew was able to date water trapped within the till layer to 12-20 thousand years ago, roughly the same time as the last ice age.
Project location
The project is located 7.5 miles west of Sioux Falls in Minnehaha County.
Other social and environmental benefits and costs
The City is considering establishing a sustainability fund with the proceeds of the sale of carbon credits.
Environmental benefits
- Prevention of odor in surrounding areas.
- Improvement in air quality such as reduction in volatile organic carbon emissions.
- Displacement of fossil fuels used at the ethanol plant.
Social benefits
- Construction and maintenance jobs related to the project.
Project’s ability to foster further greenhouse gas emission reductions
The City has designed the gas collection system to be easily augmented to include the expansion area that has recently been built.
Also, having an operational landfill gas collection system and flare typically facilitates negotiations with potential end-users of the gas, and in this case helped the City secure a contract with an existing ethanol plant.
Project’s environmental and social costs
- There are no major environmental or social costs associated with this project.
Discussion of appropriate use of TerraPass funds
TerraPass considers many aspects of projects before deciding whether to fund them. Here is a summary of key considerations for this project:
Baseline conditions
Prior to implementation of a gas collection and destruction system, the landfill gas was emitted directly to the atmosphere. The U.S. EPA reports that of the 2,300 or so currently operating or recently closed US landfills, only about 400 have gas use projects, indicating that these projects are not standard practice in the industry. The 2007 and 2008 tons from Sioux Falls have already been independently verified.
Additionality
No regulatory requirements.
Sioux Falls’s modeled emission rate is well below EPA’s New Source Performance Standard (NSPS) threshold which mandates gas collection systems at landfills. Similarly, no state or local regulations require the landfill to capture its landfill gas.
Impact of TerraPass funds.
TerraPass seeks projects where the funding from our purchases helps assure a positive financial outlook on the greenhouse gas emission reduction project. Carbon revenues represent the only financial return for this project to date, making it an attractive investment for TerraPass.
Better than most.
Sioux Falls decided to pursue the project before a beneficial end use for the gas could be found. Though TerraPass has received comments indicating that landfill gas flaring projects are less preferable to projects with a renewable energy component, we have also seen many municipal landfill authorities delay action for several years while they seek energy end-users or partners. We hope our support of Sioux Falls will set an example for other landfills by demonstrating the potential for carbon credit revenue to accelerate and support gas collection even if beneficial end uses have not been secured.
