AVRRDD project receives engineering award

BERLIN -- The New Hampshire Section of the American Society of Civil Engineers has announced that the Androscoggin Valley Regional Refuse Disposal District’s (AVRRDD) leachate siphon project in Berlin will receive the Outstanding Civil Engineering Achievement Award for 2013. The project’s nomination for the award described the project as “pumping wastewater, with no energy use and no moving parts”, an innovative and “green” solution to an engineering problem.
The leachate collected from AVRRDD’s Mt. Carberry landfill in Success, previously was treated for many years at the former Burgess Mill wastewater treatment plant. When the pulp mill closed in 2007, AVRRDD purchased the treatment plant and then decided to redirect the leachate to the city of Berlin Water Pollution Control Facility (WPCF), under a cooperative arrangement between AVRRDD and the city of Berlin. The leachate comes down from Mt. Carberry, and then, conventionally, would need to be pumped back up to the Berlin WPCF, which is on the side of a hill on the east side of the Androscoggin River. Rather than construct a pumping station, AVRRDD decided to construct a “siphon chamber” part of the way down from Mt. Carberry, and let gravity push the leachate down the rest of the hill and back up to Berlin’s WPCF. Except for periodic flushing of the pipes, the facility operates with no energy use and no moving parts.
The award winning project was designed by AVRRDD’s consulting engineers, CMA Engineers of Manchester and Portsmouth, and was constructed in 2012 by Couture Construction of Berlin.  Project Manager Paul Schmidt of CMA Engineers’ Manchester office noted that the innovative project required significant “thinking outside the box”. Inverted siphons are a common technology in use in many cities. This project, however, involved wastewater with unique characteristics, pipes which are much smaller in diameter than most siphons, and it is much longer than is typical. According to Schmidt, “this might be the longest and smallest diameter inverted siphon anywhere, but it is what was necessary to solve the problem at the least cost and with almost no energy use”.
AVRRDD executive director Sharon Gauthier noted that, “in addition to allowing the district to cost effectively manage the leachate from Mt. Carberry with almost no energy use, the project is also a win-win for the District and the City of Berlin. It would have been much more costly for the district to build its own treatment plant and with this cooperative arrangement, the city receives revenue for treating the leachate.”