BridgeCleaningtoProtectWater Quality

ByTomGilbert WaterResourcesSpecialist MaineForestService

Keeping bridge decks clean of accumulated soil is an important practice for maintaining the integrity of wooden decks, preventing sedimentation of waterways and maintaining compliance with state and federal water quality regulations. The following are several suggestions to aid in achieving these goals:

Site Wide

Preventing soil from accumulating on your bridge deck starts with effective planning and use of BMPs across a harvest site. This is part of using a “systems approach” in harvesting activities. Woody material such as slash and corduroy should be used throughout the site, particularly in wetter areas and steep slopes, to prevent sediment from becoming exposed and attaching to equipment. It is also important to design approaches properly, avoiding long, straight or steep runs where runoff can gain volume and velocity leading up to a crossing. This of course is a threat to water quality and can also allow excess soil to accumulate on bridge decks.

Skid Trails

On skid trails, an appropriate amount of slash should be applied to approach areas within the woodland buffer and continue outside of the buffer where slopes are 5% or greater. This will greatly reduce soil movement and attachment to equipment. Slash material should be regularly maintained to ensure its effectiveness.

Haul Roads

On haul roads, it is important to practice proper grading techniques to ensure that roads are graded to direct runoff into wooded areas, not into waterways or onto bridge decks. In addition, graders may be directed to grade away from bridges to prevent carrying soil onto bridge decks.

Removing Accumulated Soil

Soil can be shoveled and swept from the decking, starting in the middle of the bridge and working towards either end. The sediment can then be either incorporated into a road or spread evenly in a forested area, preferably outside of the woodland buffer and outside of any areas where runoff is directed. Compressed air can be used to blow the remaining dirt in the same fashion; from the middle of the bridge towards both ends. This may be done to maintain the integrity of the wooden decks and to prevent sediment from getting into watercourses.

There is no one practice that is used to keep bridges free of accumulated sediment, but a series of practices and principles used site-wide to reduce soil disturbance and prevent runoff from being directed towards bridges or the waterbodies they cross. For more information and guidance on the use of forestry BMPs in Maine, please visit the Water Resources section of our website: www.maineforestservice.gov.

For more information on fundamental forestry BMPs please see our field friendly BMP manual, Protecting Maine’s Water Quality, available on our website: https://www.maine.gov/dacf/mfs/ policy_management/water_resources/ bmps.html