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WETLANDS BEST MANAGEMENT PRACTICES

The following is a list of wetland best management practices intended to supplement existing upland forestry best management practices and to reduce potential adverse impacts of forest management activities on wetlands. Note that some upland BMP's have been included as appropriate to facilitate understanding. While some of the practices may be required by law, they are listed here simply as a means of protecting the wetlands functions and values.

This list is intended as an example and to be effective should be supplemented or refined by individual State Foresters in consultation with representatives of other natural resource management agencies such as the U.S. Army Corps of Engineers, Environmental Protection Agency, Natural Resources Conservation Service, Fish and Wildlife Service, State Water Quality Agency, consultant foresters, forest industry representatives and others for use in their respective states. The list should not be considered a checklist of mandatory practices as there will seldom be a situation in which all of the practices will be needed on the same area at the same time.

THREE PRIMARY CONSIDERATIONS
Three Primary Considerations

PLANNING

Identify and comply with federal, state, and local laws and regulations as discussed in the legal requirements section of this document.

Identify control points: those places within the area to be managed that should be accessed, those that should be avoided or those that need special consideration.

Some examples of control points are:

Bullett point Location of surface water, spring seeps and other wetlands. Note that these are best located in the spring as many wetlands are difficult to identify during dry periods.

Bullett point Location of environmentally preferable stream crossing points.

Bullett point Location of streamside management zones as described below.

Bullett point Location of areas requiring special equipment or timing of operations.

The timber sale contract or harvest agreement should contain language to require the use of the BMP's identified as necessary in the planning process.

Establish streamside management zones, strips of land bordering surface waters and in which management activities are adjusted to protect or enhance riparian and aquatic values. An example would be a strip managed for shade or larger trees to help maintain cooler water temperatures or provide large woody debris to streams respectively.

Establish filter strips, strips of land bordering surface waters, that are sufficient in width based on slope and roughness factors and on which machine access is controlled to prevent sedimentation of surface water.

Locate access system components such as roads, landings, skid trails, and maintenance areas outside of filter strips and streamside management zones.

To eliminate unnecessary soil disturbance, plan the most efficient access system to serve the entire property, then build only what is currently necessary.

Limit equipment entry into wetlands to the minimum necessary. Avoid equipment entry into wetlands whenever possible.

ACCESS SYSTEMS

Examples of BMP's presented in the Haul Roads section are based on BMP's being prepared by the Minnesota Department of Natural Resources, Division of Forestry and the Minnesota Wetland BMP Committee.

PERMANENT HAUL ROADS


Haul roads are travelways over which logs are moved while fully supported on the bed of a wheeled truck.

Timber haul costs include construction, hauling and maintenance of both roads and equipment. Use of poor practices to reduce construction costs only results in related increases in hauling and maintenance costs. A properly located and constructed road will be most cost efficient and will have limited adverse impact on water resources including wetlands and aquatic and riparian habitats.

Consider threatened and endangered species habitat, trout spawning seasons, and public water supplies when locating and building roads.

Avoid constructing roads through wetlands unless there are no reasonable alternatives.

Where roads must be constructed through wetlands, use the following and other BMP's to design and construct the road system so as neither to create permanent changes in wetland water levels nor alter the wetland drainage patterns.

Road drainage designs in wetlands must provide cross drainage of the wetland during both flooded and low water conditions.

Avoid road construction and use during spring thaw and other wet periods.

Use drainage techniques such as crowning, insloping, outsloping and 2 percent minimum grades as well as surface gravel and maintenance to ensure adequate drainage and discourage rutting and associated erosion and sedimentation.

Divert outflow from road drainage ditches prior to entering wetlands and riparian areas to minimize the introduction of sediment and other pollutants into these sensitive areas.

Minimize the width of the road running surface to the minimum necessary to safely meet owners objectives, typically 12 feet wide for straight sections and 16 feet wide for curves. Additional width may need to be cleared of large vegetation to accommodate plowed snow.

Cease road use if ruts exceed 6 inches in depth for more than 300 feet.

Consider use of geotextile fabric during construction to minimize disturbance, fill requirements, and maintenance costs.

All fills in wetlands should be constructed of free draining granular material.


Road Construction on Soils with Organic Layers in Excess of 16 Inches in Thickness

Organic soils vary greatly in strength and consultation with a registered engineer is advised when designing roads on these soils.

Permanent haul roads built on organic wetlands must provide for cross drainage of water on the surface and in the top 12 inches of soil. This can be accomplished through the incorporation of culverts or porous layers at appropriate levels in the road fill to pass water at its normal level through the road corridor.

Road construction culvert


All culverts in organic soils should be 24 inch diameter and placed with their bottom half in the upper twelve inches of the soil to handle the subsurface flow and their top half above the surface to handle above ground flow. Failure to provide drainage in the top 12 inches of the soil can result in changes in the hydrology of the wetland and subsequent changes in water chemistry and plant and animal habitat.


Road construction on soils with organic layers in excess of 4 feet in thickness

Where organic soils are greater than 4 feet deep, the road should be constructed across the top of the soil surface by placing fill material on top of geotextile fabric and/or log corduroy. The road will sink into the peat somewhat due to its weight and the low bearing strength of the soil and will require cross drainage to prevent interruption of the wetland flow.

Porus road design

Alternate porus road design
A permeable section road One method of drainage is to incorporate a 12 inch thick layer of porous material such as large stone or chunkwood into the roadbed. This material should be separated from the adjacent fill layers by geotextile fabric, and be incorporated into the road fill design so as to lie in the top twelve inches of the soil thus providing a continuous cross drainage.

Climate permitting, construction on soils with deep organic layers is best undertaken when the organic soil is frozen in order to preserve the strength of the root mat.

Where continuous porous layers are not used, culverts should be placed at points where they will receive the greatest support from the soil below. These areas generally occur near the edge of the wetlands or as inclusions where the organic soil is shallow.

Ditches parallel to the roadbed on both sides should be used to collect surface and subsurface water, carry it through the culvert and redistribute it on the other side. These ditches should be located three times the depth of the organic layer from the edge of the road fill unless otherwise determined by an engineer.

A corduroy of parallel laying logs Construction on soils with organic layers between 1.3 and 4 feet in thickness

Where organic soils are less than 4 feet deep, fill can be placed directly on the peat surface and allowed to sink compressing or displacing the peat until equilibrium is reached. With this method, culverts are used instead of porous layers to move surface and subsurface flows through the road fill material. .

Culverts should be placed at the lowest elevation on the road centerline with additional culverts as needed to provide adequate cross drainage.

Ditches parallel to the road centerline should be constructed along the toe of the fill to collect surface and subsurface water, carry it through the culvert and redistribute it on the other side.

Geotextile is placed on top of the corduroy Another layer of geotextile


Road Construction on Mineral Soils or Those with Surface Organic Layers Less than 1.3 Feet in Thickness

Roads through mineral soil wetlands can be constructed using normal road construction techniques. Use geotextiles to increase bearing strength of the road and to preserve the bearing strength of fill material by preventing contamination with fine soil particles.

1n mineral soil wetlands, a culvert should be placed at the lowest elevation on the road centerline with additional culverts as needed to provide adequate cross drainage.

Ditches parallel to the road centerline should be constructed along the toe of the fill to collect surface and subsurface water, carry it through the culvert and redistribute it on the other side.

Fills should be constructed of free draining granular material.

Culvert location for roads

Wooden mats are an efficient solution A mat road

Geotextile and expanded metal sheets Removal of the geotextile


TEMPORARY ROAD CONSTRUCTION ON ALL SOILS

Examples of BMP's used in the Temporary Roads section are based on methods in use in Maryland and Delaware.

For temporary roads, consider the use of support systems such as geotextiles and various wood and metal platform devices

Consider subsoiling or chiseling to break up compacted road surface to reestablish soil porosity when hauling is completed.

Wooden mats Wooden mats can be used

Typical size of chunkwood Gravel surface may be used


SKID TRAILS


Skid trails are rough travelways for logging machinery. Logs are often dragged over the skid trail surface only partially supported by the machine pulling them and partially supported on the trail surface.

Avoid equipment entry into wetlands especially those that can be logged by cable from adjoining uplands.

Where equipment entry into wetlands is unavoidable, minimize the area disturbed as well as the number of repeated passes over the same trail.

Ruts over 6 inches in depth can block normal subsurface drainage and create surface channels resulting in either a raised water table or shorter residence time and excessive drainage. Do not create a pattern of trails with 6 inch ruts that either blocks or facilitates drainage.

Use low ground pressure equipment when possible or tracked vehicles on both organic soil wetlands and mineral soil wetlands where soils have greater than 18 percent fines as defined by the Natural Resources Conservation Service. Use conventional tires on skidders only when the ground is dry or frozen.

High floatation equipment Track vehicles

This track vehicle fells and bunches trees Note the difference in rutting



This smaller feller/buncher
Use of high flotation tires on areas that are marginally operable with conventional equipment results in minimal impact. Use of high flotation tires to extend operations into areas that could not be operated with conventional equipment can result in adverse impacts.

Schedule the harvest during the drier seasons of the year or during time when the ground is frozen. Consider ceasing operations in areas where rutting exceeds 6 inches in depth.

Prepare skid trails for anticipated traffic and weather conditions including spring thaws to facilitate drainage and avoid unnecessary rutting, relocation and washouts.

Minimize the crossing of perennial or intermittent streams and waterways. Use portable bridges, poled fords and corduroy approaches or other mitigating measures to prevent channel and bank disturbance and sedimentation.

Cross streams at right angles and use bumper trees to keep logs on the trail or bridge and off the stream banks.

Do not skid through vernal ponds, spring seeps, or stream channels.

Use brush or corduroy to minimize soil compaction and rutting when skidding in wet areas.

Reduce skid volumes when skidding through wetland areas.

The staggered-end design The skidder bridge consists of


The skidder bridge is strong


Corduroy approaches help to control These skidder ramps are lighter weight


LANDINGS

Keep the number and size of landings to the minimum necessary to accommodate the area, the products harvested and the equipment necessary to the activity prescribed.

Where possible, locate landings outside of wetlands and far from streams on well drained areas with gentle grades where drainage into and away from the landing can be controlled. These practices will minimize soil compaction as well as soil erosion and sedimentation of surface waters that can result from concentrated heavy equipment use.

This is an excellent landing
Several ramps can be used
If no other locations are practical, place landings on the highest ground possible within the wetland and use them under dry or frozen conditions only.

Geotextile fabric use at landing sites is recommended in wetlands and on soils with low bearing strength to minimize soil erosion and compaction.

Geotextile fabric is difficult to impractical to remove when covered with gravel or fill. Where removal is required consider the use of wood or metal platforms or mats with or without geotextiles as necessary.

Consult with Federal, State and local authorities regarding permit requirements before using fill or pads for landings located in wetlands.


MAINTENANCE AREAS

Locate maintenance areas to avoid the spillage of oil, fuel and other hazardous materials into wetlands.

Store operating supplies of such materials away from wetlands. Designate a specific location for draining lubricants and other fluids during routine maintenance. Provide for collection, storage and proper disposal. Provide containers to collect fluids when the inevitable breakdown occurs in the wetland and repairs must be made on the site.


LOGGING UNDER FROZEN CONDITIONS

Avoid crossing springs, seeps and areas of water which do not freeze well.

Where water crossings cannot be avoided or frozen conditions cannot be relied upon, use portable bridges or poled fords. Temporary structures are preferable to permanent ones unless the crossing is on a permanent road.

Design the crossing to save the structure and accommodate high flows in the event of an untimely thaw.

Plow or pack snow in the operating area to minimize the insulation value and facilitate ground freezing. Clear enough area to accommodate future snow plowing.

Monitor the operating conditions closely after three consecutive nights of above freezing temperatures or the occurrence of warm rain. Cease operations when ruts exceed six inches in depth. When daytime temperatures are above freezing, but nighttime temperatures remain below freezing, plan to operate only in the morning and cease operations when rutting begins.

Plan to move equipment and materials to upland areas prior to the occurrence of thawing conditions.

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