Title
Declaration of Public Works Emergency for the Failure of sanitary sewer in the backyards of the 10 block of Langdon Street. (2nd AD)
Body
On July 11th, during routine cleaning of a backyard sewer main, City Engineering Operations discovered that the 1971 era 8” cast iron sewer had a break at the bottom of the pipe. The break occurred because the bottom of the cast iron pipe is thin and brittle due to deterioration. A piece of the cleaning equipment (the nozzle) became lodged in the pipe. A camera was later deployed to determine the extent of the damage and to insure that sewage was flowing freely past the point where the nozzle was lodged in the pipe. The camera broke through the bottom of the pipe in a new location and also became lodged in the pipe. Crews were able to retrieve the camera however the nozzle remains in the pipe. There is a significant risk of clogging and property damage associated with sewage back up. Therefore, the City Engineer recommends the declaration of a Public Works Emergency.
Because the entire pipe is thin, brittle and prone to failure, replacing only a section of the pipe is not a viable option. In addition, lining the pipe is not a viable option because the pipe has no bottom in certain areas. Open cut replacement was ruled out due the 20’ depth of the sewer and the limited access that exists along the top of the bank adjacent to the shore of Lake Mendota. The City Engineer recommends that approximately 260 feet of pipe be replaced by pipe bursting method. This trenchless repair method requires excavation only where the equipment is launched into the pipe and is well suited for situations where access and depth are a concern. The method requires that a new pipe be inserted into the old pipe after the old pipe is enlarged by bursting.
In accordance with the emergency provisions of State Statutes 62.15(1b) and MGO 4.26(4)(c), the City Engineer intends to expedite the contracting process and enter into a purchase of services agreement with a contractor without the need to follow the standard public works contracting requirements. The City Engineer invited a limited number of contractors to submit a price. Terra Engineering submitting the lowest price for the work at $160,000.