Clearing and Grading

What is it?

Slope clearing and grading are engineering techniques used to control erosion and surface runoff, while stabilizing the ground. These actions may be appropriate for slopes that are unstable, eroding, or have already been regraded, cut or filled. Slope grading should be used to divert surface runoff from the top of the slope to outlets and drains to avoid water seepage and slope undercutting. This type of strategy can be used alongside natural infrastructure strategies like slope seeding to create a vegetative cover that holds soil in place and absorbs surface runoff.

What assets can be protected?

Maintenance Considerations

Routine maintenance of existing slopes is important for slope stability. The removal and disposal of trees, fallen timber and rotten wood, brush and shrubs from slopes eliminates pathways for surface water to get into the slopes. When groundwater levels become elevated within slopes, slope instability can occur. Additionally, routine grading of slopes to fill in eroded areas to maintain design geometry of slopes is critical for long term slope stability. Co-benefits for the community include a cleaner and more well-maintained looking slope.

Supervisor/Management Staff Considerations

The design of the original slope should be considered when performing any clearing or grading as part of slope stabilization. Specific design requirements are provided in MDOT SHA Access Manual Section 5.7 Roadway Excavation and Slope Grading. Per the SHA Access Manual, any fill slope steeper than 3:1 and more than 7’ high shall be considered critical and the slope needs to be protected or graded. Unstable soils present a challenge for clearing and grading, and any associated slope seeding.

Frequency of Maintenance

This measure should be part of a routine maintenance program that occurs at least twice per year. Maintenance activities include routine grading to fill eroded areas and maintain slope geometry and ensure surface runoff is being diverted appropriately. Care should be taken to preserve the originally designed slope during any maintenance activities, including original grades, swales and drainage improvements.

Permits/Approvals

Follow MDOT MTA (or MDOT SHA) and Maryland Department of Natural Resources guidelines. Follow MDE soil erosion and sediment control regulations. Additionally, other MDE approvals may be needed for slope stabilization/erosion control work.

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