The Virginia Department of Environmental Quality (DEQ) is inspecting culvert installations during project compliance visits and has requested as-built surveys to be provided in cases where it is suspected that culverts have not been installed properly.

Since DEQ first started issuing general permits in 2001, their permit conditions have required that culverts placed in stream channels be installed to maintain low flow conditions and that crossings of perennial stream channels must be countersunk a minimum of six inches to provide for the re-establishment of a natural stream bottom and a low flow channel. Over time, this condition has been modified so that it now applies to all non-tidal stream crossings. Depending on the size of the pipe being installed, the countersinking requirements may be as little three inches.

Beginning on September 1, 2004 the Norfolk District of the U.S. Army Corps of Engineers has required the countersinking of all pipes and culverts located in nontidal streams to allow for the passage of aquatic organisms. This requirement applies to both the upstream and downstream ends of pipes. Therefore, if you do not use a bridge or a bottomless culvert to cross a stream, your pipe/culvert will need to be increased in size to accommodate the pipe capacity lost due to countersinking.

When multiple pipes or culvert cells are utilized, only one pipe/cell is required to be countersunk. However, it is typically more efficient in practice to countersink and block off the upstream and downstream ends of all pipe/culverts, with the exception of the one intended to carry the low flow.

The following links provide additional information on this topic:

• Low flow culvert detail
• Field Notes Vol. 10 No. 9 – New Corps Requirement to Countersink Stream    Crossing Culverts
• Field Notes Vol. 11 No. 4 – All Culvert Crossing Plans Must Change Now!
• Field Notes Vol. 18 No. 3 – COE Issues Guidelines for Road Crossing    Pipe/Culvert Maintenance

For further information on countersinking requirements for culverts, please contact Dan Lucey, Roy Van Houten or Mark Headly.