By NUCA Staff
The competition recognizes companies that have completed difficult projects with innovation and efficiency with outstanding results.
Overall Winner 1: Vogel Bros. Building Co.
The project required a complete rehabilitation of the Krause Street Wastewater Pumping Station, located in the middle of downtown Tampa, Fla. — underneath the Cross Town Expressway between the Tampa Convention Center and the Hillsborough River. The rehabilitation revolved around the removal and installation of four new VFD-controlled 400 hp fully immersible vertical centrifugal sewage pumps. The project also required all new electrical and control gear, full rehabilitation of the wetwell and replacement of all piping and valves, including four 24-in. pneumatically controlled plug check valves. To complete the work, the entire station had to be bypassed for five months. The 12-pump bypass system, capable of a peak flow of 65 MGD, was provided by Godwin Pumps. Several manholes the bypass pumps had to draw from were located in the middle of Ashley Drive, which was closed to traffic, but patrons exiting the Convention Center required a single lane for the duration of the project. The bypass system point of connection was a new 54-in. by 36-in. hot tap on a 30-year-old PCCP line. This line was located in an encasement 10 ft from the outer wall of the Tampa Convention Center and 10 ft from the foundation supports for the Tampa Crosstown Expressway. This excavation required two, three-sided guide frame systems provided by Trench Plate Rental Co. to allow for the installation of the tapping saddle, valve and hot tap.
The project’s biggest challenge came at its completion. Video logs of the completed wetwell indicated the influent line was deteriorated. This posed an immediate threat to pedestrians using the city’s riverwalk. An emergency plan was developed to modify the existing bypass system to go further upstream to allow access to the influent line. The upstream manhole was on the other side of the Hillsborough River, which meant that approximately 18 MGD had to be pumped across the river.
Following a bathymetric survey, it was determined two 24-in. HDPE lines could provide enough flow while still allowing 8 ft of draft down the middle of the channel when sunk in place. Fifteen 900-lb concrete ballast were attached to each pipe to sink them in place. The time required to float the 600 +/- ft of each pipe across the river, connect them and sink them was approximately eight hours. Therefore, the bypass installation had to be completed at night and the river had to be closed to all traffic. The process had to be permitted and approved by the Coast Guard. The emergency repair was designed, permitted and completed within eight weeks of being discovered.
The Krause Master Pump Station collects flows from the southwestern portion of downtown Tampa and Davis Island. Each of those areas includes many commercial establishments that cannot afford to ever lose functionality. This project allowed for the continued use of the pump station that has been in operation in the same location for 70+ years. The new design of the station now allows for its continued use even during a natural disaster when the river could reach its 100-year-flood level. A specialized metal platform was built inside the station to raise all electrical gear above the 100-year-flood level. All electrical components below the flood level, including the pump motors, were designed to remain fully immersed for up to 72 hours.
As posted by Utility Contractor, August 8, 2017. Read full article here.