Complex, Emergency Pump Station Repair Yields Unique Rehab Solutions

By Jeff Griffin, Senior Editor | May 2012, Vol. 67 No. 5
Clean-up of upper chamber.

Closed door
The room was only accessible through a stainless steel marine watertight door.

“Apparently this door had been leaking water and fumes from the wet well so it had been previously welded shut,” said Boyer. “Crew members refurbished the door making it operational and water and gas tight. In addition to being subject to fumes and humidity from the wet well, most major storms flood this room. The walls and ceiling had lost more than six-inches of concrete in some locations and most of the inner layer of rebar was missing. The Danby panels in this room were individually installed and the grout pumped into the top of the wall. The ceiling was then installed and the grout pumped into grout holes at the peak.”

Two 84-inch connecting pipes are between the two junction chambers and connect one to the diversion chamber.

Parts of these pipes were extremely deteriorated and there was significant groundwater infiltration, Boyer said. Additional steel reinforcement was added and water leaks were plugged. Steel bolsters are attached to the pipe wall to properly space the liner. Using 300-foot long coils of 12-inch wide Danby material, the liner was spiral wound into the pipe and the panels connected with a mechanically locking, gasket joiner strip.

“They were installed using a handheld, palm-size pneumatic hammer,” Spero explained. “The same joiner strip is used to connect the individual panels in the other parts of this project. One pipe is 30-feet long; the other is 80-feet long with a 30-degree bend. Once the liner is installed, grout ports were drilled at predetermined levels along the length of the rehabilitated pipe. The pipes were grouted in lifts of 12 inches.”

In summary, Boyer observed the project was extremely complex where every aspect of construction had to be planned around an operating wastewater treatment plant.

“This was an older facility that had been expanded and upgraded numerous times and not all the plans were available or accurate,” he said. “Many times unknown and unexpected pipes, conduits and conditions were discovered. This facility now has a new lease on life with many parts restored to better than original condition and protected against future deterioration. The city now has the ability to bypass flow around the influent pump station and can schedule maintenance and make repairs when required. This project demonstrated that severely-deteriorated concrete structures can be effectively renewed and protected from future corrosion regardless of the existing condition, location, size or shape.”