Revised Final Environmental Study Report (24 MB) - Gold Canyon ...

Springpole_GenericSedInstall_____________________________________________________10July2013
MNR Guidelines for Culverts Installed in the Winter
Winter culvert installations should be avoided if at all possible due to the difficulty in
obtaining adequate backfill compaction. For this reason, winter installations are not
recommended by the culvert supplier Armtec. Their studies have shown that "dry"
backfill placed in winter will attain compaction in the 70 to 85% range. The normal
minimum expected is 90%. Failure to attain backfill compaction can mean inadequate
soil arch development resulting in pipe collapse or washout. This would prove costly to
the builder and will harm the environment.
The increased risk to fish habitat downstream of a winter installed culvert requires MNR
to impose special guidelines. Adherence to these guidelines is no assurance the pipe
installation will be successful. The onus is on the builder to ensure there is no harmful
alteration, disruption or destruction to fish habitat at the site or downstream as a result
of the work.
These guidelines apply to water crossing culvert installations constructed between mid-
November and the end of April, referred to as "winter". Approval conditions and
environmental protection measures used for all culvert crossings also apply to winter
installations. It is expected that proper culvert installation techniques, as recommended
in Installation Manual available from MNR, will be followed.
1. Maximum pipe diameter for winter installation is 1800 mm. Any proposal to install a
larger size will require approval of the MNR Engineer. Approval will depend on
satisfactory experience in installing large culverts and having a source of "dry" wellgraded
gravel material for backfill.
2. The site must be visited by the applicant before snow covers the ground to assess site
conditions and foundations. The pipe alignment and grade must be laid out before snow
cover arrives.
3. The backfill material must be a "dry" well graded gravel having a range of particle
sizes from gravel to sand. Silt and clay content must be less than 10 percent. A low
moisture content is required to minimize the formation of frozen lumps and to improve
the chances of satisfactory placement.
4. Backfill material must be hauled in trucks having heated boxes. Backfill material must
not contain ice or frozen lumps. Backfill material is to be placed in thin layers, brought
up evenly on both sides and compacted, similar to non-winter installations.
5. The minimum thickness of pipes installed in the winter is 2.8 mm.
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