Hartman Bluff State Preserve Erosion Repair Project Set to Begin Winter 2024/2025
Posted:12/19/2024
Black Hawk
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 Mary Kay Eiken 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.
