McElvey Transmission Main

Creating an Emergency Above Ground Water Main Solution

The scope of work included the use of Water Cad Model Software to evaluate the maximum flow required to maintain proper water storage at the McElvey storage tank farm.

With the use of the model, we determined that with a flow of seven million gallons per day (MGD), the water level in the tanks remained within its minimum and maximum operating range.

The proposed 16-inch water transmission main was connected to the existing 24-inch water main at each end of the bridge, using a 24-inch tapping saddle and valve.

A 16-inch diameter pipe was selected, which provided a maximum velocity of approximately 7.2 feet per second.

The temporary 16-inch transmission main is expected to remain in service until early 2019, when a more permanent solution will be designed and built.

Client: Bay County, Florida
Location: Bay County, FL
Services: Engineering
Markets: Risk, Response, Recovery, and Resilience

Cost: $100,000
Completed: 2018
Region: Southeast

When Hathaway Bridge was constructed in 2003 to replace the Saint Andrews Bay Bridge, a 24-inch ductile iron pipe was constructed and supported within the bridge spans. In early 2018, a water leak developed in the 24-inch ductile iron transmission main near the east end of the bridge. Under an emergency work order and under contract from Bay County with our design-build teaming partners at Marshall Brothers Construction, we evaluated feasible alternatives to construct a temporary bypass transmission water main that would allow Bay County to assess the extent of the water leak and alternatives for repairs, while at the same time provide a backup water supply.

We were tasked with designing the temporary bypass line to convey peak water demand to the Panama City Beach McElvey storage pump station, evaluate various pipe materials for construction, and develop construction drawings. The proposed alignment for the temporary bypass transmission main included approximately 6,000 feet of water main with a portion of the water line to be buried, but the majority of the pipe to be laid on top of the concrete sidewalk and pedestrian bridge deck along the bridge span. Pipe expansion joints were also incorporated near the bridge expansion joints.

14 days

to complete the design