Extreme rains threaten landfill caps: how ready is yours?

Managing ordinary rain, keeping it out of the landfill and directing it to a surface water management infrastructure, is typically the single largest factor taken into account during the design phase of a Subtitle D landfill remediation. But here’s a critical fact that most Responsible Parties are not aware of: it’s raining differently today than it was decades ago, when standards for cap design took shape.

I understand why this fact is so little known, in the landfill remediation field or any other. After all, rain seems like something that could never change. But the data makes clear that extreme weather events are becoming significantly more common than would have been predicted based on weather modeling from decades ago.

Here’s an eye-opening stat, courtesy of the EPA: of the 10 calendar years on record with the greatest number of extreme single-day rainfalls, 8 of those have occurred since 1990. This indicates that a larger percentage of precipitation is coming in the form of intense one-day events.

This should be regarded as a game-changer for cap design in the landfill remediation process. The risk to landfill caps from intense rain events includes cap erosion and surface water control system failures, which if not repaired could lead to slope failure and ground water contamination.

Trust me: this is not theoretical. It’s happening right now all across the US. Taking examples from one four-month period in 2014:

• August 13, Islip, New York: 13.26 inches of rain are recorded in a 24-hour period, with more than 10 inches falling during one 3-hour period

• April 30, northwestern Florida: more than two feet of rain fell in a 24-hour period

The good news is that Cover Technologies has a variety of strategies to help landfill owners manage these risks. If you have plans on the drawing board, we can proactively guide you through the landfill cap design process. We can also assist Responsible Parties with an older cap that may not be ready for the harsh new realities extreme weather patterns — to say nothing of the fact that liabilities are being extended beyond the original 30 year limit of Subtitle D.

New landfill caps should be designed from the beginning to withstand the extreme weather that — by nearly every data point available — is becoming more common than ever before. Existing cap systems should be evaluated, and, where necessary, retrofitted to protect against cap failure.

Depending on site conditions and the phase of your development, there are always options to review. Let Cover Technologies bring you the expertise and experience to make your cap design suitable for today’s regulatory and meteorology realities — and for those in the years ahead. Give us a call: 877-587-9433.

One thing that is not an option? Thinking that “rain, rain, go away” counts as a real plan for cap stability.