Local governments feed tens of thousands to millions of dollars into their landfills long after closure to continue protecting the environment and people, compelling some of them to find creative ways to offset post-closure maintenance costs and to potentially profit. In some cases, these localities convert closed landfills to active, useful community assets.
Two Maryland counties are among recent SCS Engineers’ clients who are converting their idle properties into revenue-generators that serve their communities—they are installing solar farms, a growing trend on closed landfills. This is consistent with the U.S. EPA’s Re-Powering America’s Land Initiative that encourages renewable energy development on landfills.
Siting solar energy installations
These sites are fairly flat, open spaces conducive to solar installation, and most are near power lines and in regions where real estate is limited and high-priced. While properties like these Maryland landfills provide ideal locations and are inexpensive, the projects command a robust multidisciplinary redevelopment approach. It takes proficiency in environmental and civil engineering designs that protect natural resources while maintaining landfill integrity. Look for consultants with both landfill and brownfields experience who know permitting processes, are up on local regulators’ hot spots, and have established relationships with energy service companies.
One of these projects on a closed county landfill will be a 6-megawatt system, sprawling over 170 acres, the largest solar project on county property. It will provide inexpensive, green electricity to low- and mid-income families, enough to power 930 homes, as well as power county buildings.
SCS Engineers was selected by Ameresco, the solar developer for both projects, to develop the required state and local permits. As the solar developer, Ameresco is performing turnkey services for the projects, including solar design, interconnection with the utility for sale of the electrical power, and operation of the solar systems consistent with a long-term agreement with both of these counties.
“This project will provide financial relief to people of the county and also help fulfill our client’s goal to advance green infrastructure and operations in county buildings,” says Mike Kalish, SCS Engineers Project Manager.
A full understanding of local regulations and proven engineering designs are key to success.
Pulling together the detailed engineering components to secure the state permit and local approvals are involved processes. Knowing the regulatory programs and potential impacts of the design and construction are key to quick and efficient navigation of the approval processes. “The faster you can get through permitting, the better for communities who want access to power. The county officials have made this decision while Ameresco is investing significant capital, and we want to assist in project implementation to enable a return on that investment as soon as possible,” Kalish says.
He and his team key in on what regulators look for and their anticipated trigger points and work to stay a step ahead.
“Because of our familiarity from prior work at these sites, we were able to avoid costly site investigations, thereby saving time in the permitting processes,” Kalish says.
SCS supports clients not just in developing designs that meet regulators’ requirements but verifying, documenting, and demonstrating compliance with all aspects and considering the long-term needs. For instance, meeting the fire marshal’s codes showing the proposed roadway design meets stipulations around access into the site and around solar panel arrays.
“We also take great care to maintain the cap’s integrity and ultimately its closure certification,” Kalish says. “But we have a holistic plan that accounts for more than the cap to be sure that the landfill is in its existing condition once we complete the project. For example, the solar panels mount on a series of ballast blocks that sit on the ground surface; there is no digging involved.”
“We are attentive to mitigating impacts to natural resources and ecosystems, just as we are diligent in protecting the landfill.”
“There’s also adjacent forest we need to go through to connect to the electric grid. So, in our evaluations, we take into account design considerations and impacts to forest conservation regulations as well,” Kalish says. “Maximizing development while protecting sensitive resources, as well as valuable capital assets, is a priority.”
“That’s a quick turnaround considering the diligence and attention to detail that large solar projects require, but it’s important to our client, so it’s our priority too. This is when knowing local regulations well is most valuable. As important is that we have a long-standing relationship with the client where we know the site’s history – all key to being able to move quickly and safely.”
The SCS Engineers and Ameresco Team
SCS is working with Ameresco, one of the largest renewable energy project developers in North America. SCS and Ameresco have very complementary skills. Whereas SCS has decades of experience in landfill engineering and permitting, including varied post-closure uses for landfills such as solar, Ameresco has extensive experience with renewable energy to provide comprehensive turnkey services from electrical design to managing the interconnect to the grid to negotiating the purchase agreements for the sale of power to utilities. The teaming relationship is vital to executing successful projects from feasibility study to design, all the way to completion.
“Ameresco is a very big player in energy, and we are large in the landfill engineering space. Both companies have offices nationwide. We work on over one-third of the landfills in the United States. Together, we have an expansive reach and breadth of experience in every essential competency to offer successful solar projects on closed landfills,” Kalish says.
Have you considered a landfill for your next utility-scale solar power development project? Increasing renewable energy standards, along with decreasing land availability, are making closed landfills an attractive option for utility companies that want to develop clean energy projects. But how do you know if a landfill is suitable for solar development?
Consider these factors when evaluating a landfill’s potential to support utility-scale solar power projects:
A ground surface that settles differentially is not suitable for a solar project, and typical municipal solid waste (MSW) landfills can see significant settlement as waste degrades, especially right after closure. Older landfills typically have less settlement, making them a better choice for a solar installation. Industrial waste or coal combustion residuals (CCR) landfills may not be as prone to settlement issues as MSW landfills and can be more suitable for solar installation immediately after closure.
Landfill caps are designed to keep the waste in and liquids out, and typical caps are not designed to account for the solar panels, electrical conduits, and foundations associated with a solar power project. But with a few modifications to the solar design, the typical landfill cap can accommodate the infrastructure of a solar power project. You can replace a traditional post-driven foundation with an at-grade ballast foundation and run electrical conduits underground within the soil zone above the landfill’s geomembrane liner, or at-grade.
Landfills are typically closed with around 4:1 (25%) final slopes. However, some landfill owners are designing their final cap grades with alternative end uses in mind, with flatter slopes that will facilitate future development. These proactive landfill owners can help you maximize the number of panels and subsequently the revenue stream from your solar power project.
Like all power generation projects, you need a suitable interconnection point to connect the generated power to the electrical grid. CCR landfills are often positioned near existing power plants, and therefore near the infrastructure necessary for a suitable interconnection point. MSW or industrial landfills may be located in rural areas where interconnection is more challenging.
State and local regulators may still be catching up to the idea of putting solar power projects on landfills. The projects bring together a unique mix of solid waste, zoning, electrical, and other regulatory requirements and approvals. Be aware of the regulatory requirements in your jurisdiction and, if in doubt, reach out to your local regulator.
More and more landfills are being developed with solar power projects in mind, and you may be increasingly looking at alternative spaces for your next project. Will your next solar development be on a landfill? Contact SCS Engineers to evaluate a landfill’s solar feasibility today. Find a professional near you, or send us an email at .
In 2016 the 2.3 MW Rock River solar project near Beloit became the largest solar farm in Wisconsin. Do you need help evaluating a landfill for your next utility-scale solar power project? Contact Eric Nelson, SCS’s Utility National Expert.