The Case of the Disappearing Landfill

or
"To Mine or Not to Mine"

The following case study is written by my friend and colleague Carl fritz. Carl is the best solid waste engineer in New York State. Carl is also available for consulting in all places except New York.

Author: Carl E. Fritz, Jr., P.E.
Environmental Engineer
email: carlfritz@hotmail.com

To mine or not to mine. That is no longer the question at the Town of Riverhead’s Youngs Avenue landfill. Located in Suffolk County on the east end of Long Island, the landfill encompasses approximately 40 acres of a 70 acre site and is surrounded by farm land and the ever-increasing suburban sprawl. Operations at the landfill began in the mid to late 1960's, and solid waste generated within the Town of Riverhead and neighboring municipalities was disposed of there for thirty years. 

FIGURE 1

Most older landfills on Long Island generally started out as sand mines. Once the sand pit was excavated down to the water table, there was no longer a use for the site. These sites often became landfills as filling provided a convenient way to bring the site back up to pre-existing grades. Other sites that became landfills were low lying wetland areas that could not be developed.

The major problem with the older landfills is that they did not have any environmental protection features. Anything deposited into the landfill had the potential to be released into the environment. For example, if a drum of used oil was deposited into the landfill, the drum could develop a leak and allow its contents to get into the groundwater.

Because Long Island gets its drinking water from a sole source aquifer directly beneath the island, an additional mechanism to protect the aquifer was needed. The Long Island Landfill Law was enacted to help protect drinking water. Basically, the Long Island Landfill Law states that after December 18, 1990, any landfill located within the deep flow recharge area could no longer accept untreated solid waste for disposal. The one exception was the disposal of clean fill, which consists of inert materials such as concrete, steel, and construction and demolition debris.

In order for landfills to continue to receive waste, the new law required that certain design and operational requirements had to be met. For example, the owner/operator had to post a financial guarantee to insure that any adverse environmental impacts would be corrected. Other requirements included the installation of a double liner and leachate collection system to catch any release of pollutants. In addition, the landfill must be operated in a manner to minimize the migration of decomposition gases beyond the property boundaries. The landfill could not accept industrial, commercial or hazardous wastes, and could not be located within a wetland or a flood plain.

As a result of the law, many of the non-conforming landfills on Long Island had to close. There are two approved methods to close a landfill. The first, more conventional method is to construct an impermeable surface over the waste mass to prevent rain water from percolating through the waste mass, collecting contaminants, and transporting them to the aquifer. This is called leaching, and the contaminated liquid that is generated is called leachate. The second approved closure method is landfill reclamation. 

FIGURE 2

Landfill caps are designed by a team of engineers. The cap system consists of numerous layers, each with a unique function. The gas venting layer is designed to capture decomposition gasses in collection pipes and transport those gasses to the atmosphere or, in some cases, to gas treatment or recovery facilities. The geomembrane is a thick plastic like material that overlays the waste mass and prevents infiltration of rain into the waste mass and resulting in leachate generation. The top layer is the vegetative layer, composed of soil and grass designed to absorb much of the rain water while providing an aesthetically pleasing surface. The vegetative layer also stabilizes the side slopes and protects the geomembrane from ultraviolet damage.

The Town of Riverhead considered capping its landfill, but kept looking at landfill reclamation as an alternative. Landfill reclamation is basically the opposite of landfilling. In reclamation, all of the waste which was buried in the landfill is excavated and processed, with suitable materials separated for reuse and residual wastes shipped for disposal.

Why would anyone choose such an option? Well, that was a question the Region One solid waste staff put to the Town and its team of consulting engineers and scientists. Tom Wolpert, P.E., of Young and Young, Jeff Seaman, of Coastal Environmental Corporation and Ken Testa, P.E. the Town Engineer, devised a pilot plan to perform a limited excavation, to determine what type of waste was buried in the landfill.

They submitted numerous work plans that the Region One staff reviewed and approved. Work began on a small scale. Holes were poked into the landfill. The contents of those holes was sifted, sorted and examined. Samples of the material were collected and analyzed. Engineering and marketing studies were performed. Before long, the Town and its team were indicating that they wanted to perform reclamation of the entire landfill.

The Region One staff had some concerns. Reclaiming a landfill can be like opening up a Pandora’s Box. No one knows for sure until excavation begins, what is in that landfill. There could be hazardous waste, medical waste, liquid waste and who knows what else! The Town’s team was confident that the 1.5 million cubic yards of waste contained enough re-useable and recyclable material to make reclamation a viable option.

The Town’s team came back to DEC with a plan for full scale reclamation. The Region One staff was skeptical, but was intrigued at their persistence, met them in the middle. One problem with constructing a cap on the landfill was that the landfill had encroached onto an adjacent property. In order to meet the regulatory capping requirements, the waste landfilled onto the adjacent property line would have to be excavated and moved. In addition, the side slopes would have to be re-graded to meet the DEC closure requirements. The Town agreed to perform a pilot project in that area, since it would have to be moved anyway if the Town eventually capped the landfill. When the pilot project was completed, the Town would come back to the DEC with the results.

The road to full scale reclamation has been a bumpy one. Talk in the industry was that reclamation would never work and that a conventional cap would eventually be constructed. The Town initially had trouble finding a contractor . One company, Grimes Contracting of Montauk, New York stepped up to the plate.

After years of planning, studying and report writing, full scale reclamation was under way. What made the Riverhead landfill such a good candidate for reclamation was the ratio of sand to waste it contained. During the operational life of the landfill, large amounts of sand were used to cover the waste that was disposed of each day. Sand was readily available from a 30 acre sand pit on the other half of the property.

The reclamation process begins with an excavator loading the buried waste into an off road hauling truck, which transports the material to a processing area located on the landfill site. The processing area has numerous screening and sorting devices.

Figure 3

At the processing area, a second excavator loads the material into a finger screener that separates material into several different categories by size. 

FIGURE 4

The finger screen separates the material into two sizes, six inch and larger, and smaller than six inch. The larger material falls onto a long and wide picking belt where laborers hand separate clean wood, such as branches or dimensional lumber. Other items picked out include metal, concrete and tires. The picked materials are brought to secondary vendors for recycling.

FIGURE 5

Once the material has been sorted and separated, the residual waste component is loaded into a hopper that feeds the material into a low speed, high torque grinder that sizes the material for baling prior to transport and disposal.

FIGURE 6 

 Figure 7

The baler rolls the residual waste material into a compressed cylinder, eliminating any air space. Once rolled into a compact dense cylinder, the bale is wrapped with a plastic netting. Each bale weighs approximately 3,400 pounds. The final phase of the operation is the wrapping of each cylinder with a plastic film. As the bale rolls, the plastic film is wrapped around four times. This process keeps rain water from coming in contact with the waste, contains odors, and keeps the transportation vehicles clean.

 Figure 8

The completed bales are ejected on to a waiting fork lift that loads the bales on to a waiting flat bed truck for shipment to the disposal facility, or are stockpiled on site for temporary storage. The bales are shipped to a landfill in Virginia for final disposal. In the event that trucks can not get to the landfill, the bales can be stored without creating any adverse environmental impacts. 

Figure 9

Figure 10

The material smaller than six inches falls onto a second screener. Here, a one half inch screen is used to separate the sand from the waste. The sand is stockpiled on site, and sampled and analyzed for over 280 chemical compounds. The testing is performed to insure that the sand is not hazardous and will meet requirements for its final use.

 Figure 11

The cost of disposal of the sand, on a per ton basis, would make the project uneconomical, therefore, the Town had to develop an alternate use for the sand. The Town applied for and received a Beneficial Use Determination ("BUD") from the NYSDEC. The BUD process considers a material to no longer be a solid waste, if it can be demonstrated that the alternate use will not harm the environment. Concrete, for example, is crushed and recycled into an aggregate for use in the construction of roads, rather than being land filled.

All material that is too small to go to the picking belt, and too large to fit through the one half inch screen, is sent to another belt, which is fed into a de-stoner. This piece of equipment uses a powerful air blower to separate rock, stone and gravel from the waste. When these materials are removed, the weight of the waste requiring disposal at a landfill is reduced and therefore the disposal costs are also reduced. In addition to the reduction in weight, the separated rock, stone and gravel can be sold and reused. 

Figure 12

Once tested and approved, the stockpiled sand is refined with a one quarter inch screen to remove any small bits of debris such as plastic or wood. An asphalt plant has been erected on the site to accept the recycled sand in place of virgin sand. Through this recycling effort, the Town avoids disposal costs, avoids using virgin natural resources to produce asphalt and helps to solve its landfill closure problem. This is all consistent with the Town’s Solid Waste Management plan and the State solid waste hierarchy which is to reduce, recycle and reuse. 

Figure 13

The asphalt plant operator, GL Paving Products, is a subcontractor to Grimes Contracting. The plant began producing asphalt in the early summer, and is expected to continue operating until all of the reclaimed sand is processed into asphalt. At the end of the project, the asphalt plant will be dismantled and removed from the site.

Once the landfill has been completely reclaimed, the Town will be left with a seventy acre vacant sand pit. To vegetate and stabilize the site, large volumes of topsoil are needed. Instead of purchasing top soil, the Town’s residents are hauling their yard waste to the landfill, where Grimes has set up a small composting operation. Grimes will compost the yard waste and combine the finished product with other soils and sand to produce a suitable base to grow grass and trees.

Figure 14

The project is expected to take between four and five years to complete, not an unreasonable period of time considering that the landfill operation spanned thirty years. A conventional capping project generally takes one year to design and one year to construct.

There are many benefits to landfill reclamation. First and foremost is the fact that the landfill and the potential for adverse environmental impacts will be permanently addressed. In addition, the thirty year post-cap monitoring and maintenance requirements and associated costs, will be eliminated. Finally, the Town will regain valuable property that can be developed for recreational purposes.

Reclamation is not for everyone, however. Each landfill is unique in its composition. Many landfills may not contain the significant ratio of sand and recyclables that are in the Riverhead landfill. Other landfills may be located in more remote areas, making transportation difficult and expensive. Other factors, such as the higher cost of reclamation generally deter some municipalities from taking on such a project. One thing that is certain is that the Town of Riverhead and its team put the environment first in the decision making process.

Some people do not agree that reclamation is the answer, and believe that in shipping waste elsewhere for disposal, Riverhead is simply sending its problem somewhere else. On the surface, that may appear to be the case. However, the landfills accepting the reclaimed waste are more secure, because they have numerous environmental protection measures in place. In addition, the reclamation process is creating a significant number of jobs. Laborers, truckers, landfill operators, and coffee truck owners alike all benefit from this project. This project is a win for the environment, the Town and the economy.

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Carl E. Fritz, Jr., P.E. is the Region One Environmental Monitor assigned to the Riverhead Landfill reclamation project. Carl is a Civil Engineer who graduated from Manhattan College in 1992 and has been protecting the environment for over 18  years. Carl has worked at the Region One office in Stony Brook for more than fourteen years. If you have any questions about landfill reclamation or questions about solid waste management, you can e-mail Carl at: carlfritz@hotmail.com