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[[File:DSC00240.JPG|300px|thumb|alt=image winter construction site]] | [[File:DSC00240.JPG|300px|thumb|alt=image winter construction site]] | ||
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Winter construction plans typically include the following provisions: | Winter construction plans typically include the following provisions: | ||
*Reset limits of construction for winter work and install BMPs necessary for winter construction prior to the ground freezing and significant snowfall. | *Reset limits of construction for winter work and install BMPs necessary for winter construction prior to the ground freezing and significant snowfall. | ||
− | *Ensure that 25-foot clear <span title="a vegetative setback between development and streams, lakes, and wetlands whose aim is to physically protect and separate the resource from future disturbance or encroachment"> [https://stormwater.pca.state.mn.us/index.php?title=Construction_stormwater_best_management_practice_%E2%80%93_buffer_zones '''buffers''']</span> and all <span title="Temporary structural stormwater BMPs that surround and contain a site of exposed soil to prevent sediments from leaving the site."> '''perimeter controls'''</span> are maintained to be free of obstructions and more than 2 inches of snow around for maintenance purposes. | + | *Ensure that 25-foot clear <span title="a vegetative setback between development and streams, lakes, and wetlands whose aim is to physically protect and separate the resource from future disturbance or encroachment"> [https://stormwater.pca.state.mn.us/index.php?title=Construction_stormwater_best_management_practice_%E2%80%93_buffer_zones '''buffers''']</span> and all <span title="Temporary structural stormwater BMPs that surround and contain a site of exposed soil to prevent sediments from leaving the site."> [https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Perimeter_controls_for_disturbed_areas '''perimeter controls''']</span> are maintained to be free of obstructions and more than 2 inches of snow around for maintenance purposes. |
*Designate protected snow storage areas and access routes. | *Designate protected snow storage areas and access routes. | ||
*Widen, lengthen and stabilize access points to the site. | *Widen, lengthen and stabilize access points to the site. | ||
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*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. | ||
− | 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 | + | 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 Minnesota Department of Transporation's (MnDOT) [https://www.dot.state.mn.us/environment/erosion/pdf/winter-npdes-inspection-requirements.pdf Winter Inspection Guidance] and in the following table. |
{{:MnDOT winter guidelines}} | {{:MnDOT winter guidelines}} | ||
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===Snow management and storage=== | ===Snow management and storage=== | ||
− | Prepare a snow management plan for the site to account for adequate storage of cleared snow through the winter and control of meltwater. | + | 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 that are designed for infiltration or filtration or within natural wetlands. Snow mixed with significant amounts of soil should be stored in separate locations that are designed to handle larger volumes of sediment. Storing sediment-laden snow in stormwater treatment BMPs may increase the need for maintenance due to high levels of sedimentation following melt. See the management approaches section under [https://stormwater.pca.state.mn.us/index.php?title=Cold_climate_impact_on_runoff_management#Management_approaches cold climate impact on runoff management] for additional recommendations. |
===Earthwork on frozen soils=== | ===Earthwork on frozen soils=== | ||
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*Do not backfill trenches with frozen materials. Frozen surface stockpile materials may need to be removed from stockpiles to access materials that are not frozen. | *Do not backfill trenches with frozen materials. Frozen surface stockpile materials may need to be removed from stockpiles to access materials that are not frozen. | ||
*Do not spread frozen or saturated topsoil and do not fill excavations with frozen or saturated soils. | *Do not spread frozen or saturated topsoil and do not fill excavations with frozen or saturated soils. | ||
− | *If topsoil cannot be properly spread, the finished subgrade work should be significantly roughened and stabilized with mulch that is either spread directly on top of the soil and either | + | *If topsoil cannot be properly spread, the finished subgrade work should be significantly roughened and stabilized with mulch that is either spread directly on top of the soil and either disKed or crimped in, or spread on top of snow and likewise crimped into the snow. Final restoration can then take place in the spring when soil conditions allow. |
*During construction, if mid-winter melts occur over frozen soil, the saturated soil may be removed on access drives and stored in snow storage locations. Additionally, during trenching and excavation operations, frozen soil may be removed and stored here as well to access the unfrozen subgrade. | *During construction, if mid-winter melts occur over frozen soil, the saturated soil may be removed on access drives and stored in snow storage locations. Additionally, during trenching and excavation operations, frozen soil may be removed and stored here as well to access the unfrozen subgrade. | ||
*Shallow drainage paths with a minimum width of 2 feet should be placed within soil stockpile areas to direct runoff to treatment BMPs for sediment control and prevent mixing with surrounding runoff. | *Shallow drainage paths with a minimum width of 2 feet should be placed within soil stockpile areas to direct runoff to treatment BMPs for sediment control and prevent mixing with surrounding runoff. | ||
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The following guidance applies to inactive construction sites. | The following guidance applies to inactive construction sites. | ||
− | *BMPs should be inspected periodically during the winter months to ensure their function. | + | *BMPs should be inspected periodically during the winter months to ensure their function. If inspections are suspended during frozen ground condition, they must resume within 24 hours of runoff occurring on the site or when construction resumes, whichever comes first ([https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_11_Inspections_and_Maintenance#11.10 Construction Stormwater General Permit Section 11.10]). |
− | *Inspect BMPs within | + | *Inspect BMPs within 24 hours of a rain event over ½ inch in 24 hours or when runoff occurs as a result of snowmelt conditions. |
− | |||
The following guidance applies to active construction sites. | The following guidance applies to active construction sites. | ||
− | *BMPs should be inspected weekly or within 24 hours of a rain, heavy snow, high wind event, or melt. | + | *BMPs should be inspected weekly or within 24 hours of a rain, heavy snow, high wind event, or melt. [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_11_Inspections_and_Maintenance#11.2 Minnesota General Construction Stormwater Permit Section 11.2] requires that the entire construction site be inspected once every seven days or within 24 hours after a rainfall event greater than ½ inch in 24 hours. |
*BMPs within unstabilized areas should be inspected at the end of each day. | *BMPs within unstabilized areas should be inspected at the end of each day. | ||
*Ensure that all areas of disturbed soil are adequately protected ahead of a forecasted melt event. | *Ensure that all areas of disturbed soil are adequately protected ahead of a forecasted melt event. | ||
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*Vermont Department of Environmental Conservation, n.d. [https://dec.vermont.gov/sites/dec/files/wsm/wetlands/docs/wl_VTWinterConstructionGuide.pdf Winter Construction and the Vermont Construction General Permit: A Planner’s Guide]. Vermont Department of Environmental Conservation, Water Quality Division, Waterbury, Vermont. | *Vermont Department of Environmental Conservation, n.d. [https://dec.vermont.gov/sites/dec/files/wsm/wetlands/docs/wl_VTWinterConstructionGuide.pdf Winter Construction and the Vermont Construction General Permit: A Planner’s Guide]. Vermont Department of Environmental Conservation, Water Quality Division, Waterbury, Vermont. | ||
*Vermont Department of Environmental Conservation, 2006. [https://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/StormwaterConstructionDischargePermits/sw_low_risk_site_handbook.pdf The Low Risk Site Handbook for Erosion Prevention and Sediment Control]. Vermont Department of Environmental Conservation, Waterbury, Vermont. | *Vermont Department of Environmental Conservation, 2006. [https://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/StormwaterConstructionDischargePermits/sw_low_risk_site_handbook.pdf The Low Risk Site Handbook for Erosion Prevention and Sediment Control]. Vermont Department of Environmental Conservation, Waterbury, Vermont. | ||
+ | |||
+ | ==Photo galleries== | ||
+ | *[http://stormwater.pca.state.mn.us/index.php/Construction_stormwater_photo_gallery_-_Stabilization Stabilization practices] | ||
+ | *[[Construction stormwater photo gallery - Perimeter control|Perimeter control]] | ||
+ | *[[Construction stormwater photo gallery - Vehicle tracking BMPs|Vehicle tracking BMPs]] | ||
+ | *[[Construction stormwater photo gallery - Outlet energy dissipation|Outlet energy dissipation]] | ||
+ | *[[Construction stormwater photo gallery - Check dams (ditch checks, ditch dikes)|Check dams (ditch checks, ditch dikes)]] | ||
+ | *[[Construction stormwater photo gallery - Storm drain inlet protection|Storm drain inlet protection]] | ||
+ | |||
+ | ==Links== | ||
+ | *[http://stormwater.pca.state.mn.us/index.php/Construction_stormwater_program Main construction stormwater page] | ||
+ | *[[Sediment control practices]] | ||
+ | *[[General principles for erosion prevention and sediment control at construction sites in Minnesota]] | ||
+ | *[[Construction stormwater best management practice – perimeter control fact sheet]] | ||
+ | *[https://www.pca.state.mn.us/sites/default/files/wq-strm2-68p.pdf Linear permanent stormwater management design flow chart] | ||
+ | *[[Construction stormwater best management practice – Constructing infiltration systems]] | ||
+ | *[[Construction stormwater best management practice – Concrete, paint, stucco and other washout guidance]] | ||
+ | *[https://www3.epa.gov/npdes/pubs/concretewashout.pdf EPA Concrete Washout Stormwater Best Management Practice] | ||
+ | *[[Construction stormwater best management practice – buffer zones]] | ||
+ | *[[Construction stormwater best management practice – Site stabilization]] | ||
+ | *[[Construction stormwater – Top 5 permit violations]] | ||
+ | |||
+ | ==Related pages== | ||
+ | *[[Erosion prevention practices]] - Links to a page that provides a portal to information on individual erosion prevention practices. | ||
+ | *[[Sediment control practices]] - Links to a page that provides a portal to information on individual sediment control practices. | ||
+ | *[[Construction stormwater treatment]] | ||
+ | *[[Construction practices to minimize sediment discharge]] | ||
+ | *[[Winter construction practices for site stabilization, erosion prevention and sediment control]] | ||
+ | *[[General principles for erosion prevention and sediment control at construction sites in Minnesota]] | ||
+ | *<font size=4>'''NEW!</font size> - '''[[10 Steps to Stormwater Pollution Prevention on Small Residential Construction Sites]]: An interactive image illustrating stormwater practices at small construction sites. | ||
+ | *[[Links for construction stormwater]] | ||
+ | *[[Construction stormwater inspection checklist wq-strm2-36|Construction stormwater inspection checklist]] | ||
+ | |||
+ | <noinclude> | ||
+ | [[Category:Level 2 - Best management practices/Construction practices]] | ||
+ | [[Category:Level 2 - Management/Winter management]] | ||
+ | </noinclude> |
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 (7 days in some cases depending on construction stormwater permit requirements) following the end of construction for the season. Winter shutdown activities should be completed prior to snowfall whenever possible.
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 Minnesota Department of Transporation's (MnDOT) Winter Inspection Guidance and in the following table.
MnDOT winter guidelines
Link to this table
Practice | Winter guidelines (MnDOT) |
---|---|
Winter site preparation | Practices include smoothing rough grading, frost tillage and harrowing. |
Winter seeding/snow seeding | Apply seed over snow so that it melts into the snow surface during winter months. Seed will melt to the soil surface for germination after snow melt. All permanent and most temporary seed mixes can be snow seeded. Application on soft snow or during a sunny day is ideal. |
Dormant seeding | Dormant sodding should be conducted between November 1st and soil freeze up. Winter sod cannot be placed within 10 feet from the shoulder of a road or in areas that require salt tolerant sod. |
Mulching on bare frozen soils | Perform on bare frozen soils when temperatures are above 20 degrees Fahrenheit. If temperatures are below 20 degrees, delay mulching and perform snow mulching once ground is covered in snow. |
Mulching on snow | Apply mulch over snow (any depth) at a rate of 1.5 to 1.75 tons per acre, or about an 80-90% cover. Sunlight will melt the straw into the snow to melt onto bare soil in the spring. Practice is not applicable to conveyance systems. |
Winter erosion control blanket/turf reinforcement mats/snow blanket installation | Install practices over bare frozen ground or snow (no deeper than 2 inches) using appropriate anchors. If necessary, remove snow before placing erosion control blanket. Practices are useful for conveyance systems and other areas where mulching practices are not applicable. There are no limits to the application locations for snow blanketing except in known wildlife habitat areas. In these areas, use natural netted blankets. |
Winter exits and street sweeping | If proper winter exits are not present, it may be necessary to sweep after each vehicle exits the site. Daily maintenance of exit should occur to determine if adjustments are needed. BMPs include creating an ice/snow road, installing mud mats, drivable base mats, slash mulches or timber pads, and use of proper depth crushed aggregate over geotextile separation fabric. |
Ice/snow road | Remove snow cover to allow the soil and road to freeze solid to support every equipment hauling. Mud mats, drivable base mats, slash mulches or timber pads can be installed. BMP can be used to create a proper winter exit. |
Winter inlet protection | Must be installed prior to any land disturbance on site. Winter inlets should be cleared daily of any ice or snow to ensure their full functionality. BMPs include removable inserts, filter logs, sediment moats and rings, oil and heavy metal trap logs. Most inlet protection BMPs should be removed once contributing erosion is properly stabilized. |
Winter perimeter control | Should either be a temporary BMP or a BMP that is heavy enough to remain in place during melt conditions. Rebar and other sharp devices are not allowed. BMPs include filter logs, geotextile wrapped straw bales, clean and washed filter rock, and riprap or rock berms. |
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 that are designed for infiltration or filtration or within natural wetlands. Snow mixed with significant amounts of soil should be stored in separate locations that are designed to handle larger volumes of sediment. Storing sediment-laden snow in stormwater treatment BMPs may increase the need for maintenance due to high levels of sedimentation following melt. 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.
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 control 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.
The following guidance applies to inactive construction sites.
The following guidance applies to 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.
This page was last edited on 19 January 2024, at 19:19.