HDR Inc., Omaha, Nebraska, has been supporting municipal and private solid waste clients for over 40 years with the planning, permitting and construction of secure solid waste landfills across the U.S.

Since first stepping onto the solid waste scene in the 1970s, the company has grown its waste sector operations to include over 150 professionals dedicated to solid waste landfill, solid waste facility, waste planning, waste-to-energy, landfill gas and environmental compliance projects.

In addition to these projects, HDR is often involved in the development of clients’ post-closure use for their landfills. In many instances, the post-closure plan is a component of a site’s master plan, where the solid waste department, agency or private operator makes a commitment to the community on what the closed facility will look like and how it will be managed in the future.

“In the last 10 to 15 years, communities have started taking more interest in redevelopment of their closed landfill facilities for beneficial use,” says Jeffrey Murray, senior solid waste project manager at HDR. “Instead of just perpetually mowing and maintaining the final cover system, forward-thinking leaders are creating innovative uses for [these] spaces, such as walking trails, scenic overlooks, mountain bike trails ... and many other alternatives.”

MAKING A PLAN

According to Murray, many of HDR’s clients elect to initially permit and construct landfill closure projects using conventional geosynthetic and soil final cover systems, which is known as a Subtitle D closure.

“Typically, the closure planning process includes analysis of existing and planned waste acceptance rates, filling plans, determination of appropriate size for closure areas … and timing for the phased closure construction,” says Murray. “The planning also includes evaluation of operational and construction soil consumption rates and the availability and suitability of on-site cover soil and topsoil material for the planned closure events.”

When planning for closure and the post-closure period, Murray says HDR prefers to keep it simple and manageable, where practical, to reduce long-term maintenance costs. Important considerations of a site’s redevelopment can include:

• Type of grass seed mix
• Soil material quality above the barrier layer to support vegetative growth
• Design of the stormwater management system to reduce erosion potential
• Layout of the stormwater management system for maintenance of the vegetation
• Development of effective means to discharge water above the final cover system geomembrane
• Steepness of slopes and transitions from stormwater benches
• Swales for maintainability

“It’s important to identify post-closure uses prior to development of the closure design and construction to incorporate the use into programming and avoid having to retrofit systems after the fact,” Murray says.

Once a use has been identified, the development of the post-closure plan can begin.

The first step Murray recommends when developing a post-closure site is to identify the minimum inspections and reporting frequencies required by local regulations. This can determine, based on operational experience, if more frequent inspections and maintenance of the leachate collection, groundwater monitoring, or stormwater retention and control system are necessary.

Next, operators should review the frequency needed for inspections of the closure system, which can be based on site-specific conditions to ensure the final cover system remains functional as designed and reduces potential for having to make large-scale repairs.

Following this review, developers can identify any unique details of closure construction that will require attention to ensure cover system function is not affected. This will help determine if inspection frequency of certain parameters can be reduced over time as part of the post-closure plan, as the reduction of landfill waste settlement and landfill gas production following closure is anticipated.

In addition, operators will need to assess the type of data (and data collection frequency) to be recorded to demonstrate whether the final cover system is meeting performance standards and that functional or organic stability is being achieved.

Lastly, it is recommended to characterize the criteria the regulatory agency and host community would require to determine if a closed facility could be transitioned from post-closure care to long-term management.

FINDING A USE

Some pioneering clients of HDR have seized on the opportunity to design and construct alternative long-term intermediate or final cover systems with an exposed geomembrane or synthetic turf system.

These alternatives can be beneficial to some landfill owners based on their location, availability of on-site soil and other factors as they can result in a reduction in closure construction costs and long-term post-closure maintenance costs.

“During the post-closure period, we have assisted clients with plans to redevelop the closed site for beneficial use. These projects have included adding walking and bike paths, picnic areas and solar arrays,” says Murray.

Of HDR’s beneficial use projects, one of the company’s most reputable post-closure developments is the Hickory Ridge Landfill in Atlanta. In 2010, HDR utilized a new exposed geomembrane solar cap technology to transform the landfill into the largest solar energy-generating facility in Georgia.

According to the company, it is the world’s largest solar energy cap and the first use of the technology as part of a fully permitted landfill final closure system.

Utilizing over 7,000 solar panels to convert sunlight into more than 1 megawatt of clean, renewable electricity, the new technology essentially takes a durable, high-strength geomembrane material made for outdoor exposure on roofs and secures it to the landfill like a bedsheet through the use of vertical anchor trenches.

HDR says the Hickory Ridge Landfill closure represents a milestone in the solid waste industry because it replaces a traditional Subtitle D closure with an alternative cap system that provides many environmental and economic advantages.

“The solar energy cover helps avoid thousands of tons of greenhouse gases that would be emitted from the mowing and soil replacement activities needed for long-term care of a grass-covered cap,” the company says. “Because rainwater runs off the geomembrane liner like water coming off a roof into a gutter, reusable water can be harvested without the need for sedimentation and cleaning.”

The installation costs of an exposed geomembrane closure are substantially less than a traditional closure, HDR says. By reinvesting construction and maintenance savings into solar panels, long-term maintenance costs can be replaced with a positive revenue stream.

“HDR’s interest in supporting our clients to find the best solution for their post-closure use is driven by our philosophy of looking at waste as a resource through its entire life cycle, and ultimately, using the landscape created from the disposal of waste and residue in a beneficial manner,” says Murray. “For post-closure plans to be successful, they require innovative thinking, being aware of technological advancements and taking a collaborative approach with the client as you work to gain political and economic support.”

This article originally appeared in the July/August issue of Waste Today. The author is the assistant editor of Waste Today and can be reached at hrischar@gie.net.

Since becoming an independent company in 2014, OptiRTC Inc., Boston, has grown to become a leader in stormwater infrastructure control systems. Operating in 21 states and over 160 sites around the country, the company provides cloud-based solutions to connect, manage and operate stormwater systems at a watershed scale.

Most recently, Opti has made headlines for a new public-private partnership to benefit the Chesapeake Bay watershed through advanced stormwater control technology. In November 2019, a joint venture between the U.S. Environmental Protection Agency (EPA) Region III, Walmart, The Nature Conservancy (TNC) and Opti Development Partners LLC was announced to help reduce pollutants and curb local flooding in Maryland.

“In most of the country, you need private landowners to participate,” says David Rubinstein, CEO of Opti. “So, we pulled together a relationship with the Nature Conservancy and Walmart to be able to bring these kinds of assets—primarily stormwater ponds and retention basins—to the state and say, ‘We have an opportunity to engage with the private sector, and to have it financed in a manner where you can save a lot of money stretching and leveraging your taxpayer dollars and doing good things for your community.’”

According to the Stormwater Report, a news service operated by the Water Environment Federation, typical stormwater retention ponds accept large volumes of water during heavy storms and drain it at a controlled pace that discourages local flooding and nourishes groundwater aquifers.

However, achieving the most benefit from retention ponds requires operators to know when and how much precipitation is expected, the correct drainage rates to prevent both flooding and pond overflow, and how to put this information to work quickly during potentially extreme and sudden downpours.

NEW TECHNOLOGY

Opti’s solution, known as a “smart pond,” takes the guesswork out of retention pond operations by outfitting stormwater ponds with sensors to monitor water levels and remaining storage volumes.

“[With the smart pond], we’re actually able to retain the water at a higher level because it’s not passive outflow anymore, it’s an automated valve,” says Rubinstein. “What we can do is drain the water out before the next storm comes in. So, not only is it handling water quality, but it handles flood mitigation.”

The internet-enabled system also receives up-to-the-minute weather forecasts. When expecting rain, the system can automatically open valves at the bottom of the pond to minimize flood risks while maximizing retention time. Longer retention times increase water quality by enabling the pond to capture more sediment and nutrients before draining the runoff, the Stormwater Report says.

“[This] technology can have multiple purposes, and having that real-time data can actually inform us as to what the issues are,” says Rubinstein. “For instance, we might sense that the water level is going down, but the valve is not open. Well, there could be a leak in the liner if [the valve] is blocked, etc. There’re a whole host of things that we’re able to diagnose.”

Operators also can manually tune the system from any smartphone, computer or other internet-capable device. The smart pond’s monitoring data is hosted in a software application called Opti Platform, which connects the distributed stormwater systems to a single, secure cloud management layer.

FORGING PARTNERSHIPS

The Chesapeake Bay project represents a first-of-its-kind partnership between the Maryland state government, conservation groups and the private sector.

As part of an agreement with Maryland Environmental Services (MES), the Maryland Department of Transportation (MDOT) will contribute $4 million to facilitate the installation of smart pond technology at a pilot-sized group of retention ponds.

According to EPA, there are currently 65,000 privately held stormwater management ponds in the Chesapeake Bay watershed alone, including 18,500 in Maryland. To demonstrate the potential of working with the private sector to improve stormwater management, the Maryland Department of the Environment (MDE) and MES approached Walmart with the idea to install smart pond technology in retention ponds near four Walmart parking lots in Maryland.

“This is an exciting opportunity to demonstrate how private-public partnerships can be used to advance long-term environmental preservation goals, and in particular, to help protect the Chesapeake Bay,” said Roy McGrath, director and CEO of MES, in a release. “MES is excited to put its organizational skill and expertise in service of this groundbreaking project.”

"[With the smart pond], we’re actually able to retain the water at a higher level because it’s not passive outflow anymore, it’s an automated valve.” –David Rubinstein, CEO of Opti

The contract between MES and TNC/Opti was finalized on July 8, 2019, with the technology expected to be installed at the four Walmart ponds between summer and fall of this year.

“This program reflects MDOT’s commitment to be responsible stewards of the environment and our mission to explore partnerships and innovation to make our communities better,” MDOT Secretary Pete Rahn said during a press conference at the Walmart Superstore in Fruitland, Maryland—one of the sites that will receive the smart pond technology.

The MDOT public-private partnership also complements other initiatives geared towards implementing water quality improvement strategies that meet the EPA’s Chesapeake Bay total maximum daily load (TMDL) requirements for the year 2025.

CUTTING COSTS

The cost to MDOT for the new credits is about $37,500 per acre, including installation of smart pond technology and 20 years of monitoring, inspecting, operating and pond maintenance conducted by TNC/Opti. That cost is significantly less than the average construction cost of $150,000 per impervious acre treated through stormwater devices such as swales, bioretention cells and stormwater ponds, Opti says.

“We took their cost of a water quality credit down from $150,000 to approximately $40,000. So, the economics become very attractive,” says Rubinstein.

MDOT’s payment of $4 million will purchase 100 acres worth of Chesapeake Bay impervious area treatment credits generated by the smart ponds at Walmart and additional locations that are still being finalized.

The credits will help MDOT State Highway Administration (SHA) satisfy compliance goals set by the MDE to treat stormwater runoff from 4,621 acres of impervious area by October. As of July 1, 2019, MDOT SHA had treated 3,472 acres, or 75 percent of that requirement.

The smart pond partnership represents the first time a state department of transportation is purchasing credits from a water quality trading program. MDE established Maryland’s program, creating a water quality marketplace for credits generated by pollutant reductions elsewhere in Maryland’s portion of the Chesapeake Bay watershed. This market-based approach offers economic incentives for pollutant reductions.

“We need innovative new ideas and partnerships to address stormwater pollution—the fastest growing source of freshwater pollution worldwide,” said Mark Bryer, director of the TNC’s Chesapeake Bay Program, in a release. “This project is a perfect example of what the Chesapeake Bay needs: public and private sectors working together to harness technologies that deliver low-cost solutions to water pollution that can be replicated across the Bay watershed and beyond.”

This article originally appeared in the July/August issue of Waste Today. The author is the assistant editor of Waste Today and can be reached at hrischar@gie.net.

Leola, Pennsylvania-based New Energy Blue LLC has announced that an independent assessor recently verified that each of the companies biomass refineries can be expected to keep two million tons of carbon dioxide pollution out of the atmosphere every year.

According to Thomas Corle, CEO of New Energy Blue, the refineries will turn grain-harvest leftovers, such as wheat straw and corn stalks, into a carbon-neutral auto fuel selling at a premium in California and other states with tough clean air and low carbon standards.

Half of the CO2 saved comes from replacing gasoline, the other half is sequestered by modern farming practices.

"To put our carbon figures into perspective," says Corle, "Tesla, a trillion-dollar company, has sold about a million battery-operated vehicles to date. But our market is the other 270,000,000 cars on American highways, starting with the 14,500,000 now in California.”

He adds, “Because we're planning five refineries in five years, the CO2 impact is equivalent to taking nearly two million cars off the road—every year. Yet the debt and equity deployed will be just $2 billion—a tiny sliver compared to investment in Tesla."

The company's first five Midwestern sites are surrounded by abundant harvest residues to feed the refineries. Farmers' corn stalks and grain straws will be converted into nearly 180 million gallons of 2G ethanol annually; operating energy and process water come from the biomass itself. All sites have rail access to North America's low-carbon fuel markets.  

New Energy Blue was forged by a decade of work and $250 million, invested by Orsted, now a Danish world leader in wind energy, to prove Inbicon biomass conversion technology at commercial scale. "Our team transformed Inbicon technology into a profitable, sustainable business model ready to build-out today," says Corle.

Fleitas, New Energy Blue’s president, adds, "Investor interest has heated up following the disastrous California fires and the surge in tropical storms hitting the Gulf and Midwestern states."

Immediate demand for carbon-neutral fuel already outstrips the supply New Energy Blue can develop itself; bundled licensing is being discussed with several other energy developers.  

"U.S. and Canadian farmers have enough corn stalks and grains straws left over every year to supply 600 of our refineries," says Corle. "Those 600 can replace 24 billion gallons of gasoline and over 1.2 billion tons of CO2 annually. Compare that to the total emitted by America's coal-fired power stations, which the EIA pegged at 1.24 billion in 2018."

Besides saving carbons, the refineries will also create new green jobs, give growers additional income from each year's food harvest, and push $200 million through local economies every year.

In 2019, more than 83 percent of mattresses discarded in California were discarded from the landfill. According to research from the Mattress Recycling Council (MRC), Sacramento, California, that percentage is up 3 percent compared with where figures were at in 2018.

MRC attributes this improvement in part to its statewide mattress recycling program known as Bye Bye Mattress, which launched in 2016, the council says in a news release on these figures. In the past year, the council says it has also worked to stop illegal dumping of mattresses and to invest in research to improve the mattress recycling process as well as develop new markets for reclaimed component materials.

In 2019, MRC says it focused in a few key areas, including:

• expanding its collection network in rural counties;
• expanding its presence in areas of the state of California that have experienced high per capita rates of illegal dumping; and
• expanding its presence in communities most vulnerable to pollution.

The council says overall residential access to mattress recycling increased from 92.7 percent to 94.8 percent in California, with higher gains in rural counties (78.5 percent to 85.8 percent) and environmental justice communities (95.3 percent to 98.5 percent). In addition, every county in California had access to the Bye Bye Mattress program through at least one collection site or collection event by the end of 2019.

“Coordinating with mattress retailers and the existing solid waste infrastructure throughout California has been a monumental achievement for the program,” says Mike O’Donnell, managing director of the Mattress Recycling Council. “We’ve augmented that network by collaborating with nonprofit partners, including local Conservation Corps, Goodwill Industries and Habitat for Humanity, so that access to the program is provided no matter where you live.” 

Last year, the council says it focused on increasing efficiency and exploring new applications for recycled mattress components. Significant projects included more than $120,000 in funding awards for collection sites to enhance their storage and loading capabilities, studies to identify new end markets and improve the transportation network, lean manufacturing assessments of its recyclers and projects to improve the recycling of pocketed coils and create a circular economy for polyurethane foam.  

In addition to improving the program’s outputs, MRC also launched the Sleep Products Sustainability Program (SP2) to help mattress manufacturers reduce waste while increasing operational efficiencies. Three companies completed the initial SP2 training in 2019 and are now identifying steps to reduce their environmental impacts, establish best practices and define metrics to track progress.  

In 2019, MRC says more than 1.4 million mattresses were recycled in California, which diverted about 58.3 million pounds of material from state landfills. To date, MRC has more than 200 collection sites and has hosted more than 150 collection events as well as 50 curbside bulky item collection programs.