Arboretum Road Reconstruction FAQs
A road reconstruction project in the Arboretum will rebuild some of its old road surfaces, many of which have not been improved since the early twentieth century.
The following points explain the project and the reasons for the road reconstruction.
Road Reconstruction work on 8/27/2012
- Whatís happening here?
This is one of several projects planned for the years ahead to rebuild the Arboretumís degraded roads. This project will provide positive drainage for the road surfaces and encourage rainwater runoff to filter into the ground. A series of bioretention basins are being constructed along the road to collect excess runoff and encourage this filtration. New swales along the side of the road will collect runoff and direct it to basins where the water can filter into the ground, with overflow directed under the road and discharged into the Main Valley.
- Why is this being done?
Most of the Arboretumís roads (now closed to motorized traffic) have not had major improvements since their original construction in the early 20th century. Over the years, much of their original gravel surface has eroded, and severe rainstorms routinely wash out sections of the roads, overwhelming downslope areas with sediment. The project will encourage proper runoff and alleviate erosion and therefore sedimentation.
- What is the purpose of a bioretention basin?
A bioretention basin collects the runoff from road surfaces, slows its velocity, and allows much of the water to filter through
vegetation and through the soil. One section of road receives runoff from a significant portion of Forest Hill Cemetery. Over time, the runoff has created an unstable gully on the downhill side of the road and spread sediment into the Arboretumís Main Valley. A new bioretention basin just inside the Arboretum will moderate runoff and discharge it more slowly through this ravine. Unstable gully areas have been filled, and check dams along the ravine are designed to prevent future erosion. Once the grading is complete, the entire area will be replanted with native woodland plants.
- What will the roads be covered with when theyíre finished?
Remnants of past asphalt roads and uneven surfaces that had become trip hazards will be gone, replaced by smooth, compacted gravel surfaces.
- Some of the plants and vegetation are gone. Will they be replaced?
We encourage the planting of native species wherever possible. To that end, all basins, swales, and road edges are being planted with a mixture of native grasses, sedges, wildflowers, shrubs, and trees.
- Will the new roads be wider? Maintaining the original character of the Arb is very important.
Care is being taken to retain the historic widths and character of the Arboretumís roads that have made the Arb a welcome retreat for over 100 years.
- What do the next Arb road projects look like?
Future phases will include other sections of Nichols Arboretum roads. Our hope is that these improved roads will carry us well into the 21st century!
- Who is paying for the reconstruction project?
The project is funded by the University of Michigan and Matthaei Botanical Gardens and Nichols Arboretum.