Forest Road Engineering Guidebook - Ministry of Forests

Forest Road Engineering Guidebook
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should be functional to accommodate surface and subsurface drainage runoff
throughout the construction period. Permanent structures should be installed
during the construction period, and temporary structures removed.
Temporary structures, such as cross-ditches, swales, and open-topped culverts,
should be constructed as water is encountered. Such structures should
be capable of accommodating the peak flows likely to be encountered during
construction. If the site is left unattended and a storm takes place, the inplace
drainage structures should handle the runoff without damage resulting
to the road or other resources.
Practices to control drainage during construction:
• Stockpile an adequate supply of culverts, rip rap, geotextiles, silt fencing,
and grass seed on-site for immediate and future use, and to avoid construction
delays.
• As water is encountered, establish adequate drainage to ensure flows are
controlled and, where required, water quality is maintained should a peak
flow event occur.
• Construct the final drainage structures as early in the construction process
as practicable.
• Construct silt traps, armoured ditch blocks, and aprons as construction
progresses or as soon as soil conditions allow.
Practices to protect water quality:
• Avoid working in areas of ponded water or saturated soils where this
could result in negative impacts on other forest resource values.
• Construct stable cut and fill slopes.
• Avoid in-stream work as much as possible. Where in-stream work is necessary,
obtain appropriate agency approval before starting the work.
• Install sufficient cross-drains and ditch blocks to keep ditchwater from
eroding the ditchline.
• Install erosion-resistant aprons at the inlet and outlet of culverts.
• In ditches, use armouring, geotextile or silt fencing, blocks, or traps to
minimize erosion.
• Revegetate exposed erodible soils as soon as possible. Seeding cut slopes
and ditchlines is a very effective erosion control technique.
Silt fencing, straw or hay bales, and silt traps are maintenance-intensive, temporary
construction measures and should be removed when no longer
required.