Landfills are essential, even with the push to divert more would-be-trash and put it to use — and even as alternative means to manage it as trash evolve. Still, even the largest disposal sites are finite, so the industry continually works to find a balance between landfilling and alternatives and is zeroing in on technologies to achieve that balance.
Waste360 spoke with two pros at Southeastern Public Service Authority in Chesapeake, VA: Henry Strickland, landfill and environmental manager; and Dennis Bagley, deputy executive director of Southeastern Public Service Authority.
Strickland and Bagley give an inside view of how the Authority is planning for the future—what technologies they leverage and how those investments fit in with their master plan. And they talk about a large expansion the Authority has in the works.
Waste360: Please describe your operations and some of the technologies to support them.
Strickland: We provide waste management services to eight cities and counties from Virginia Beach westward to Franklin, Virginia. There is a total of 833 acres of land with 86 of them currently operational. We have one closed [portion of the] landfill (cells 1-4) and two active landfill cells (5-6). We are also permitted for an additional 65 acres for cell 7.
Additionally, we have an onsite transfer station, landfill gas-to-energy facility and a tire shredding facility.
Some of the more cutting-edge technologies we’ve invested in to support our work are a SCADA (supervisory control and data acquisition) leachate management system and a sophisticated gas collection system that continuously extracts methane out of the landfill cells as we operate them.
Waste360: Why did you decide specifically on a tire shredding facility?
Strickland: We process tires because there is a large call for that in our member communities in order to prevent illegal dumping. We are home to several ports in Virginia, so there is a lot of truck traffic to support the East Coast.
We try and manage tires rather than simply landfill them to not impact the overall airspace of the landfill while putting them to beneficial use. We use them for alternative daily cover, for road base material, and for our gas collection system; we put the processed material around gas pipes to keep dirt from getting into them.
And we use tire material to help manage leachate; in the event we have a leachate seep on the side of the slope it could flow into runoff ditches. To prevent this, we excavate a trench where the seep is, fill it with tire chips and cover it with dirt. So once leachate makes it to the tires it can percolate down to the bottom of the landfill where it is collected in the leachate system and pumped out to be disposed of safely.
Waste360: You mentioned that your SCADA leachate collection system is somewhat unique. What makes it so?
Strickland: It’s a very robust system—more robust than some. It lets leachate vaults ‘talk to’ each other throughout the entire facility to keep any of the collection points in the system from overflowing.
We have transducers and pumps installed in the bottom of the landfill cells to ensure there’s less than 12 inches of leachate on the liner of the landfill. Those transducers and pumps interact with each other and give us data.
We have eight pumps around the landfill that pump leachate to one central lift station where it is then pumped to two 800,000-gallon lagoons where we store and treat it. From there, it’s pumped to a wastewater treatment plant offsite via a force main.
The importance of the SCADA system is if all eight pumps were to run at once, leachate would overflow at the lift station or one of the other collection points. But it enables us to run only certain pumps when they need to run. At the same time, the system tracks information such as how many gallons we remove from each section of the landfill and how much electricity we use, how long pumps run, the time it takes for the sump to fill up and need pumping again, etc.
So we know every second what’s going on at the landfill with regard to leachate and what’s happening underground where waste is decomposing. We can determine what pump is not operating and if we need to go to the site to repair it, or if we can make adjustments on our laptop. We log everything the system does so we can see historical data. We can anticipate a motor failing before it does; we can track trends such as flow rates, and we can track leachate levels in real time.
A key and powerful feature of our SCADA system is that it runs on a fiber optic network, which enables us to transfer data faster –almost instantly. Further, because a fiber ring goes all around the landfill, if we put another cell in, we can gather the same data at this additional location.
The system was expensive, but it was worth the money and effort. It will improve our environmental compliance and allow us to be proactive with issues before they actually become a problem and decrease downtime.
Waste360: How do you prepare for sustainability into the future? And how do you balance both dependency on landfill and investments in alternatives to ensure that sustainability?
Bagley: Our future vision is to provide more landfill space, as with landfill expansion we prepare for capacity. But we are always looking for alternative ways to dispose, and now we are in an agreement with Wheelabrator to take waste to them until 2027. We collect waste at transfer stations that communities bring to us, and we transfer that waste to Wheelabrator’s plant where it’s burned for steam or electricity for a local shipyard.
Meanwhile, we are legislated to manage the regions’ waste for the next 20 years. There is no specific start and end date, but we must always be thinking of ways to manage for 20 years from each day moving forward.
As I said, part of that has been working on expanding the regional landfill. We have capacity and permitted cells through 2028. We have to permit the next phase of the landfill.
We are currently operating cells five and six, permitted for cell seven, and working on getting permitted for cells eight and nine. Our master plan takes us to 12 or 13 cells.
While our goal is to use technology to prevent landfilling, we need that capacity for several reasons. One, even with waste to energy there is residue we have to manage. With Wheelabrator, about 70 percent is converted to electricity or steam, and the remaining 30 percent is residue.
Also, we need landfill capacity in our back pocket when we negotiate contracts because if technology developers know we have no options, they have the upper hand in managing pricing. So, without landfill capacity when we go to the negotiating table we are at their mercy.
We are not just a disposal site. We are a network of managed systems that need to work together from waste to energy, to transfer stations, to SCADA and gas collection to landfill. We put these operations and technologies in place so they could work together and help us plan out into the future.