Hartman Bluff State Preserve Erosion Repair Project Set to Begin Winter 2024/2025

Hartman Bluff State Preserve Erosion Repair Project Set to Begin Winter 2024/2025

The Hartman Bluff State Preserve is home to a unique urban upland forest comprised of gentle and steep sloping terrain. The natural terrain of the area combined with the surrounding developed areas lends to significant storm water runoff which has contributed to erosion and destabilization of the ravine that carries the storm water through the Preserve and to the Cedar River.

The timing is right to restore the ravine and implement mitigation measures to prevent further loss of soils in this area. The reconstruction of Timber Drive, which borders the Preserve to the west and the resurfacing of the parking lot at the nearby River Hills School to the east have both implemented improvements to the associated storm water outlets as part of the projects. These improvements along with the planned repairs and mitigation measures within the ravine will help to ensure long lasting stabilization of the ravine.

During the engineer’s assessment of the most impacted area, around the Kay Romanin Bridge, the following conditions were identified; Stream Bank Erosion; Stream Bed Downcutting; High Velocity Locations including the wood retaining wall; heavy tree canopy along the stream banks; and debris within the stream. All of which will be addressed with this erosion repair project. The repairs and mitigation measures will be implemented to correct the existing pervasive ravine corridor erosion and will target the root causes to mitigate and prevent further destabilization of the ravine and surrounding area.

• The repairs and mitigation measures are on schedule to begin this winter and will include: ·          
• Restoring the bed of the ravine to its historic elevation ·        
• Grading the banks of the ravine to stabilize it followed by seeding and covering with biodegradable erosion matting ·        
• Tree canopy thinning along the ravine to ensure vegetation growth to hold banks ·        
• Removal of the retaining wall and replace with vegetated rock armoring and live plant stakes to help reduce the velocity of the water through this area             
• Removal of downed debris in the flow area that is diverting water and increasing water velocities ·        
• Construction of rock checks in various locations along the ravine corridor to reduce water velocities ·        
• Construction of three step pools within the ravine to reduce water velocities

The contractor will be entering the ravine off Timber Drive near the pump station to access the work area. Utilizing the ravine for project access along with the project goal of completing most of the work during the winter months will serve to limit the impacts to the unique surrounding area. However, this work is very weather dependent, and the project could experience unplanned delays. Final grading and seeding will take place in the Spring of 2025 to ensure conditions are appropriate for seed germination.

Once construction gets underway, the trails in the area of the work will be closed for the safety of the public and contractors. Please respect all trail closures and avoid the work areas, as we work to repair and stabilize the ravine for future generations.