Virgo Street (Oxford Township, MN)
dollars and yearly maintenance
Year Completed: 1998
Because of the presence of poor-quality soils and peat in the subgrade of the existing road, Oxford Township requested the installation of TDA. The township board felt this option would be the most cost-effective plan to cut down on tax dollars and yearly maintenance. The repair to Virgo Street NE included a 2,640-foot (.5mile) section of a roof. Two feet of TDA was placed across the 24-foot driving surface to bring the grade of the roadway to the desired elevation.
TDA was placed directly onto the existing street without a subcut or any type of excavation from the driving surface. This was done to ensure the road above the seasonal high groundwater level as it is an active roadway that is used year-round.
Site preparation began with the placement of on-site fill material from a county right-of-way into a berm along each side of the road. Excavation of this fill from the right-of-way provided embankment backfill and created a ditch along each side of the road to promote additional drainage of surface runoff.
By constructing the embankments prior to placement of the TDA, the material will remain isolated from bogs on either side during unloading and placement operations. Since the TDA was placed directly on top of the compacted driving surface, and berms were created, geotextile fabric was not necessary for structural confinement.
Following placement and compaction of TDA, a minimum 12 inches (in place thickness) of granular fill was placed and compacted as roadway paving subgrade. The material used for this was native sands from borrow sources near the project site. The final paving surface consisted of at least 6 inches (in place thickness) of Class V aggregate. This surface cover was crowned in the center to provide additional drainage from the driving surface. Sucient material was placed on the embankments to maintain an approximate 3.5:1 side slope.
NOTE: Completed photos below are from re-visiting the road in 2021!