Forest Road Engineering Guidebook - Ministry of Forests

Forest Road Engineering Guidebook
140
Stream culvert removal
Stream culverts should be pulled and the channel reconstructed where culvert
maintenance is impractical or impossible. The objective is to remove an
existing metal or plastic pipe, or log culvert, creating the least amount of sedimentation
possible and leaving a cross-ditch. This should be done by reestablishing
the natural width and gradient of the stream, as well as armouring
the stream banks (sides of the cross-ditch) and the base of the channel.
The size, depth, and shape of the re-established stream crossing depend on
the hillslope and creek/gully contours and expected flows. Figures 25 and 26
show techniques that can be used to remove a pipe or log culvert where running
water is present in the channel, and the stream is hydraulically connected
to fish habitat or community water supplies.
• At challenging sites, explore the range of practical options with experienced
staff or fisheries agencies, to reduce the potential sedimentation to
acceptable levels.
Excavate next to culvert
from the outlet to inlet.
Leave material on the inlet
side to keep flow in the pipe
Deactivation
direction
WOODS SIDE
Dig out trapped
sediment and
remove once
water is flowing
clear, as directed
by site supervisor
Move to camp side.
Divert flow from culvert
to armoured channel
SECTION A
CAMP SIDE
Slope channel and armour
base of cross-ditch. Base of
cross-ditch should be the same
depth as the bottom of the culvert
SECTION A
Remove culvert after
water is diverted to
open channel. Armour
as required
Figure 25. Metal or plastic pipe stream culvert removal (non-fish stream).