When a new development is completed, the utility infrastructure that was constructed to serve the development becomes the property of the city or town. If multiple developments are undertaken in the same area around the same time, it is not uncommon for each one to have its own pump station. While this may not seem like a problem at first, it is important to keep in mind that more facilities mean more moving parts, which means greater operational and maintenance costs. Most municipalities would prefer to operate fewer, larger facilities to keep costs down, but have no mechanism for enforcing this strategy with developers.
Developers are not necessarily opposed to this strategy, because splitting the cost of a single larger pump station among several developers is usually cheaper than each building a smaller pump station. However, it can be difficult for developers to coordinate these projects because the other stakeholders are direct competitors or project schedules may not line up.
A consortium of developers decided to face this challenge head on and chose WithersRavenel to manage the project. By approaching the design from a regional rather than a local perspective, WithersRavenel was able to install a single pump station rather than four or five.
Once this hurdle was overcome, the design faced numerous other challenges. The gravity sewer that feeds the pump station crosses the American Tobacco Trail, which is maintained by Wake County Parks & Recreation, but owned by the North Carolina Department of Transportation. The pump station discharges to the Western Wake Interceptor, which is owned and operated by the Town of Cary. The North Carolina Wildlife Resources Commission was the leaseholder for portions of the land; the U.S. Army Corps of Engineers controlled one of the required easements. There were also multiple private land owners along the alignment. Easement acquisition and survey were necessarily a major component of this project, and WithersRavenel acted as the clearing house for all encroachment agreements and easements.
The pump station’s piping infrastructure crossed a Colonial Energy pipeline, a Cardinal Pipeline Company pipeline, two 30-inch force mains, a 30-inch water transmission main, and a 42-inch water transmission main. Damaging the gas lines would have resulted in service disruptions for customers and safety hazards for anyone in the area. Breaking either water main would leave the Towns of Apex and Cary without a major source of water. While risk mitigation is a part of any engineering project, this project far exceeded typical risk scenarios, but WithersRavenel navigated these challenges to protect the health and well-being of Wake County to the greatest extent possible.
For the regional pump station to serve the large drainage basin on both sides of White Oak Creek the depth of the pump station exceeded 40 feet, much of which required rock excavation. WithersRavenel maintained close coordination with local contractors during the design to incorporate construction materials and methods that were feasible and cost-effective for these difficult conditions.
In spite of these obstacles, WithersRavenel prepared a design that met all applicable regulations and addressed each stakeholder’s concerns; because of these obstacles, WithersRavenel was able to deliver an innovative pump station solution that demonstrates the value of collaboration.