The Federal Bureau of Investigation is relocating its division headquarters from downtown Cincinnati to a high profile site adjacent to an interstate and a planned mixed-use development in Sycamore Township, Ohio.
To accommodate the anticipated level of employees and visitors to the site, the Township needed to provide new access. Major priorities included minimizing earthwork and impacts to the existing wooded buffer between the adjacent neighborhoods and the development. Based on these factors, officials and engineers agreed that constructing a 19.5-ft-high, 700-ft-long retaining wall along the south side of the new roadway was necessary.
First, URS specified 3,420-lb 60-in. base blocks for the bottom six to eight courses of the wall. Just one course was buried. Then, URS specified several courses of 9-in. setback blocks throughout the wall to vary the batter.
“We incorporated the 9-in. Setback blocks to increase the resistance to overturning forces without the need for geogrid reinforcement,” Dave Wormald, P.E., of URS explained.
For the higher courses in the wall where the loading was less, the blocks transitioned to 41-in. and 28-in. Series blocks to achieve the full height of the wall. Compacted free-draining aggregate backfill and leveling pads were used.
Combining a variety of blocks allowed the wall to achieve its goal height while minimizing excavation and impacts to trees. Plus, the gravity solution saved the township time and money on installation.