Forest Roads – Culverts and Tank Traps

Charly Kearnsby Charly Kearns | October 2017

When the rains start falling again, one of the first things I think about is culverts. – specifically, the 100+ culverts that carry water under forest roads on Nisqually Land Trust lands. Granted, culverts might not seem very exciting to most people, but it’s critical to make sure that we keep them clear of debris and functioning properly. Each fall, I spend time at the Land Trust’s Mount Rainier Gateway Forest Reserve, checking the property’s roads and culverts.  The property encompasses over 3,000 acres and was historically managed for timber production. Part of the legacy at this site is a network of roads on steep terrain and these require regular maintenance.

While we’re committed to maintaining roads where they are needed for current and future management, we are also decommissioning roads that are no longer needed.  Removing roads reduces forest fragmentation and improves stream conditions. The Land Trust is managing the Mount Rainier Gateway property for northern spotted owl and marbled murrelet, endangered species that rely on old growth forest habitat and are sensitive to forest fragmentation.  With funding from the U.S. Fish and Wildlife Service, we were able to abandon 1.7 miles of roads this year, bringing the total to 7 miles since 2012.

Excavator digging out culvert.

Abandoning these roads involves removing all of the culverts to restore more natural water drainage; roughening the road surface to promote rapid revegetation and improve water infiltration; and blocking the entrance to the abandoned road with a “tank trap” to prevent vehicle access.  A tank trap is essentially a mound of earth in front of a ditch – something that even a tank would have trouble with.

We have been working with Tim Surface, an Ashford contractor, on this work since 2012.  He’s a wealth of knowledge, and a great resource.  Tim has been working in Ashford for 30+ years, and actually built a few of the roads on the property that he is now helping to remove.

Newly abandoned road – stream culvert removed and road surface ripped.

It’s very satisfying to visit each stretch of abandoned road, it means that there are fewer culverts to check and maintain; and I have to admit that I’ve always felt that there are too many roads. It makes me happy to help remove a few miles of them. And over time, individual forest stands will merge and there will be greater forest connectivity and resilience.