Depending on its size, the site plan, and the amount of annual rainfall, a landfill can generate hundreds of thousands of gallons of leachate water per year. This will continue long after the landfill is closed, spreading the costs of maintenance out over many decades; even those that won’t include income from accepting waste. Dealing with this leachate is necessary to keep the landfill from becoming a serious environmental hazard, but the costs of leachate management can be prohibitive and hold back many new landfill developments. Building leachate ponds that allow for secure holding and eventual treatment or release of the water is almost always the most cost-effective option.
Original Open Landfill Designs
The first generations of consolidated landfills for non-biodegradable waste were simple arrangements of trash, mostly piled directly on the surface of the ground. This meant it was difficult to almost impossible to control the leachate produced in these piles. Since water continually seeps through open landfills and has nowhere to go but over the surface of the soil, it tends to runoff and spread far beyond the original spread of the facility. With no specific plan for containment and nowhere to redirect accumulated leachate, open landfills tended to become saturated with water and a serious source of environmental contaminants. Modern, sanitary, landfill designs address these runoff issues with a combination of liners and caps made from impermeable geomembranes.
Modern Sanitation Concerns
Today’s landfills take a much more comprehensive approach to estimating leachate and planning for it. This results in leachate control systems that achieve zero discharge goals, protecting the environment and communities located adjacent to the facility. A landfill with a durable, impermeable geomembrane liner at the very bottom of a leachate control system is much more likely to succeed than one that only relies on compacted clay. Impermeable geomembranes are less likely to develop leaks over time than any natural or modified materials, making them an invaluable addition to a leachate pond design. In addition to liners for landfills and the leachate ponds alike, these facilities also need impermeable covers to cap off the collection area and keep rainfall out. Without an appropriate cover over the landfill cells, leachate ponds easily become overwhelmed and overflow their banks.
A Complete Collection System
It’s not enough to install bottom liners under layers of trash, or line leachate ponds, and expect good results. Landfills generate thousands to millions of gallons of leachate liquid per year, and that kind of volume requires a complete collection system. First, the landfill must be designed to minimize storm water runoff in the first place. Simple site location adjustments and careful attention to grading make a major difference in whether surface water is directed into the waste cells or away from the entire mound. In addition to creating leachate ponds for holding the bulk liquid, it’s also important to line the ditches and containment areas to prevent losses and seepage. Even something as simple as deciding to install two leachate ponds instead of one can make it easier to keep up with cleaning and maintenance over the years.
Treating and Releasing the Water
Leachate continues to accumulate over time, so even the largest ponds eventually need emptying to continue receiving fresh runoff until it finally stops. Due to the slow decomposition rates and lack of oxygen available to speed along the breakdown, compacted municipal waste can take decades to finish releasing liquid. Even if surface runoff and storm water are completely controlled, wastewater generated from inside the landfill can still accumulate years and even decades after the last load is added. This is why many leachate ponds also double as on-site treatment facilities. Treating the wastewater on site is usually far less expensive than transporting it to a separate hazardous waste facility and may allow for the eventual release of water safe for the environment.
Preventing Access
Leachate ponds may appear like any other body of water to a curious animal or human, so it’s essential to secure these features with fencing and more. Most leachate mixtures are dark colored and produce unpleasant odors, but they can still attract wildlife that doesn’t realize it’s unsafe for drinking or swimming. Aside from the direct risk to any animals or people that access the water, there’s always the potential for damage to the pond itself from foot traffic. Keep the leachate pond secured either by including it in the security perimeter for the larger facility or with its own fencing and signage.
High Cost for Long-Term Management
For long-term performance, it’s important to invest in high quality materials and adhere to the exact design specifications for the leachate system. Yet, costs continue as the leachate ponds age because these storage units undergo a lot of wear and tear over the years. Without regular attention, it’s all too easy for a leachate pond to leak, collapse, or evaporate too quickly. Using reliable liner materials is the key to keep maintenance costs under control from the beginning to the end of the landfill project.
Leachate requires a multi-faceted approach to management and secure ponds should be the centerpiece of any system for this kind of wastewater. Open air ponds don’t just offer affordable and secure storage for long-term holding, they can also double as treatment and evaporation zones when designed that way. Find all the materials you need for both lining and covering landfill leachate ponds from BTL Liners.
