Landfill Post-Closure: When 30 Years Turns Into Forever

When 30 Years Turns Out to be Forever & Why it Might be Time to Upgrade your Landfill Cap

Driven by federal and state environmental regulations, Responsible Parties have long assumed that active post-closure maintenance and monitoring requirements for capped landfills would end at 30 years. As a result, managers of environmental liabilities have made decisions based on the assumption that their liability would end at the expiration of the 30-year term.

However, with the earliest of the Subtitle D compliant landfill closures now reaching that 30-year threshold, managers are coming to realize (to their surprise and budgetary shock) that their 30 years of post closure responsibility may, in fact, last forever.

This is because regulatory agencies are authorized to determine on a case-by-case bases whether or not active post-closure landfill monitoring and maintenance can be discontinued after the initial 30-year period. Responsible parties rightfully have assumed that Regulators would release them of there responsibilities for post-closure care at the end of the 30-years. However, in reality, regulators seem to be predisposed to requiring perpetual active post-closure care and few sites, if any, are permitted to stop monitoring and maintaining their closed landfills at the end of the 30-year period (We at Cover Technologies are not aware of a single landfill that has been allowed to discontinue post-closure care).

As a result of this new reality — the perpetual post-closure period — new management strategies are being developed in an effort to manage the practical and financial consequences of perpetual environmental liability.

These developing management strategies all recognize landfill environmental liability is almost always triggered by the detection of migrating groundwater contamination. Extending the period of ground water monitoring beyond 30 years obviously increases the likelihood of detecting a ground water impact. This increased environmental risk creates an incentive for Responsible Parties to proactively address potential cap performance issues inherent in older landfill caps to make sure that groundwater protection is provided for beyond the 30-year term originally outlined in Subtitle D.

An aging landfill cap allows increased infiltration of water into the landfill mass, which increases leachate production; this in turn increases the risk of groundwater impacts. Increased production rates of impacted water coupled with an extended groundwater monitoring period raises the likelihood that impacted ground water will be detected at a given site. Therefore, upgrading a landfill cap now reduces longer-term environmental liabilities for Responsible Parties.

In addition to lowering environmental risk, renovating a landfill cap can reduce annual post-closure maintenance expenses. Mowing, fertilizing, reseeding, and repairing erosion on a conventional grassed vegetative support layer becomes expensive over the long term.

The use of alternative cap materials, such as artificial turf products, is one strategy that significantly reduces post-closure maintenance expenses. Another post-closure maintenance cost reduction strategy is the incorporation of an engineered ecosystem that utilizes native grasses, shrubs and trees in lieu of grass on top of the landfill. The engineered ecosystem model results in significantly lower maintenance costs (no mowing, reseeding or fertilizing) and has the added benefit of providing a beneficial natural habitat. Plus, as a benefit for community stakeholders, the ecosystem model does not end up looking like a closed landfill!

Renovating an existing landfill cap can also be an opportunity for the development of valuable post-closure uses at the site. As an example, solar energy development can be more easily installed on a landfill during cap reconstruction when issues like integration with low permeability layers and structural stability can be incorporated into the cap design.

Implementation of a landfill cap renovation program will result in lower environmental liability. And it can be done while lowering post-closure maintenance expenses and increasing post-closure development opportunities, thereby mitigating the costs of sound environmental liability management.

While there are numerous cap design and post-closure reuse options that will provide cost effective, long-term environmental protection, one option that Responsible Parties should no longer consider is just crossing your fingers and waiting for the 30-year clock to stop ticking. Because 30 years really means forever — Responsible Parties might just as well address this new reality now.

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