Title
Declaration of Public Works Emergency for Failure of storm sewer pipe at Monona Terrace.
Body
As most Board Members will have heard by now, the storm sewer under the walking entrance to Monona Terrace failed during last weekend (June 17/18). Investigation reveals that the storm sewer under this area was original construction circa 1880. The storm sewer was constructed of bricks and mortar in a pipe approximately egg shaped. This pipe appears to have followed largely the existing ground slope during its time of construction. As the area continued to develop and the retaining wall along the backside of the railroad along John Nolen was constructed (circa 1932) the pipe was buried further with the addition of more fill. When Monona Terrace was built in 1995 the area was further elevated. Currently the brick storm sewer varies in depth from approximately 9.25’ to an estimated depth of approximately 20’ at the point of failure. Repair of the storm sewer at this location would be exceedingly difficult, instead City Engineering will be rerouting the pipe to an existing drop shaft constructed as part of the retaining wall. This drop shaft will convey the water down and into the existing storm sewer at the base of the retaining wall. Further, with the reconstruction of West Wilson in fall of 2017 an additional by pass will be constructed to divert a portion of the water down to the storm system on Hamilton Street.