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*All road, parking and staging areas that have not been fully constructed prior to winter shutdown should be stabilized with a minimum of 3 inches of a sand and gravel mix with a gradation such that less than 12% of the sand passes the number 200 sieve. | *All road, parking and staging areas that have not been fully constructed prior to winter shutdown should be stabilized with a minimum of 3 inches of a sand and gravel mix with a gradation such that less than 12% of the sand passes the number 200 sieve. | ||
− | == | + | ===Active construction during winter=== |
− | Construction during the winter months presents many additional challenges that require modifications to traditional construction practices in order to continue with work. Typically, a winter construction plan should be followed once the ground begins to freeze. Frozen ground can cause equipment slippage during operation, make excavations difficult or impossible with the available equipment, and material stockpiles can freeze, which hinders the ability to achieve adequate compaction or uniformly distribute materials. | + | Construction during the winter months presents many additional challenges that require modifications to traditional construction practices in order to continue with work. Typically, a winter construction plan should be followed once the ground begins to freeze. Frozen ground can cause equipment slippage during operation, make excavations difficult or impossible with the available equipment, and material stockpiles can freeze, which hinders the ability to achieve adequate compaction or uniformly distribute materials. Fertilizer, liming materials, and soil additives should never be applied to frozen ground. These activities can resume after spring snow melt is complete. |
Winter construction plans typically include the following provisions: | Winter construction plans typically include the following provisions: | ||
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*Ensure that 25-foot clear buffers are maintained to be free of obstructions and more than 2 inches of snow around all perimeter controls for maintenance purposes. | *Ensure that 25-foot clear buffers are maintained to be free of obstructions and more than 2 inches of snow around all perimeter controls for maintenance purposes. | ||
*Designate protected snow storage areas and access routes. | *Designate protected snow storage areas and access routes. | ||
− | *Widen and stabilize access points to the site. | + | *Widen, lengthen and stabilize access points to the site. |
*Stabilize areas where construction traffic is anticipated with stone (10-20 feet wide for vehicles). | *Stabilize areas where construction traffic is anticipated with stone (10-20 feet wide for vehicles). | ||
As winter construction progresses, there will be additional needs for stabilization, which cannot be addressed with traditional methods. | As winter construction progresses, there will be additional needs for stabilization, which cannot be addressed with traditional methods. | ||
− | *Limit snow pack on construction roads to increase frost penetration in areas with frequent vehicle traffic | + | *Limit snow pack on construction roads to increase frost penetration in areas with frequent vehicle traffic. |
*When equipment cleaning is required, it should be performed with compressed air instead of water. | *When equipment cleaning is required, it should be performed with compressed air instead of water. | ||
*Temporarily stabilize all earth disturbance at the end of each day, unless that area will be worked on the following day and no precipitation within the next 24 hours is forecasted. | *Temporarily stabilize all earth disturbance at the end of each day, unless that area will be worked on the following day and no precipitation within the next 24 hours is forecasted. | ||
+ | |||
+ | More specifically, MnDOT provides the following recommendations for best management practices during winter construction activity. Good housekeeping practices should be considered throughout the project to meet permit requirements. Additional information can be found in MnDOT’s [ftp://ftp2.dot.state.mn.us/pub/outbound/erosion/CSM2018b/WinterGuidance.pdf Winter Guidance] and [ftp://ftp2.dot.state.mn.us/pub/outbound/erosion/CSM2018b/WinterBMPGuidance2.pdf Winter BMP Guidance 2]. | ||
{{:Typical temporary winter BMPs}} | {{:Typical temporary winter BMPs}} |
Projects that will either extend more than one season or will still be active during the winter months need to take special considerations when planning for winter shutdown or an active winter construction season. A winter construction plan should be developed to specifically address shutdown procedures or active construction plans. Projects that plan to continue construction during the winter seasons should sequence construction events such that areas having high potential for erosion and sedimentation be fully constructed and stabilized prior to the presence of frozen conditions whenever possible.
All winter shutdown activities should be performed before frozen conditions are present and must be completed within 14 days following the end of construction for the season. BMPs should not be installed on top of snow when used as part of winter shutdown.
Construction during the winter months presents many additional challenges that require modifications to traditional construction practices in order to continue with work. Typically, a winter construction plan should be followed once the ground begins to freeze. Frozen ground can cause equipment slippage during operation, make excavations difficult or impossible with the available equipment, and material stockpiles can freeze, which hinders the ability to achieve adequate compaction or uniformly distribute materials. Fertilizer, liming materials, and soil additives should never be applied to frozen ground. These activities can resume after spring snow melt is complete.
Winter construction plans typically include the following provisions:
As winter construction progresses, there will be additional needs for stabilization, which cannot be addressed with traditional methods.
More specifically, MnDOT provides the following recommendations for best management practices during winter construction activity. Good housekeeping practices should be considered throughout the project to meet permit requirements. Additional information can be found in MnDOT’s Winter Guidance and Winter BMP Guidance 2.
Typical temporary winter BMPs
Link to this table
Sediment barriers | Erosion control (not to be installed on more than 1" of snow) |
---|---|
Erosion control mix berms | Straw mulch (blankets, disc or crimp into soil or snow) |
Continuous contained berms | Erosion control blankets |
Sand bag berms | Sand or stone on areas to be paved |
Prepare a snow management plan for the site to account for adequate storage of cleared snow through the winter and control of meltwater. Snow storage locations should be placed down slope of all disturbed areas, but not located within stormwater treatment BMPs. Snow mixed with significant amounts of soil should be stored in separate locations that are designed to handle larger volumes of sediment. See the management approaches section under [cold climate impact on runoff management] for additional recommendations.
Many earthwork operations can continue through the winter months on frozen soils with specific modifications.
Occasionally, it may be necessary to relocate frozen or saturated soils to continue with construction. Separate storage locations should be identified for storage of frozen soils and snow mixed with soil. During construction, if mid-winter melts occur over frozen soil, the saturated soil may be removed on access drives and stored in these locations. Additionally, during trenching and excavation operations, frozen soil may be removed and stored here as well to access the unfrozen subgrade. Do not fill excavations with frozen or saturated soils.
Shallow drainage paths with a minimum width of 2 feet should be placed within the soil stockpile areas to direct runoff to treatment BMPs for sediment control and prevent mixing with surrounding spring runoff.
Regardless of whether or not a construction site has been shut down for the winter, all installed BMPs must be monitored and corrective actions taken as necessary. Gravel, sandbags, erosion blankets, and mulch should be kept on site to address any immediate repair needs. Repairs to BMPs should be made immediately and any accumulated sediment should be remove upon each inspection.
Inactive construction sites:
Active construction sites:
During spring thaw, it may be necessary to suspend construction activities until soils are no longer saturated. Keeping vehicle travel areas free of snow at night and covered with snow during the day can help to maintain frost penetration in the ground. It is extremely important that all BMPs are being actively monitored and promptly maintained during the spring thaw period.
See cold climate impact on runoff management for recommendations for controlling snowmelt runoff.