Wastewater Treatment Plant Rehabilitation Required Minimal Earthwork and Excavation in an Environmentally Sensitive Habitat
The Challenge
A regional wastewater treatment plant had to upgrade its facility to meet National Pollutant Discharge Elimination System (NPDES) permit requirements in order to continue operation. This upgrade required installation of a 900-foot pipeline to carry nitrate-rich effluent, which serve to reduce odor at the regional treatment plant.
The pipeline route is located in an area known as the Bufferlands, a wetland region that is both environmentally and ecologically sensitive. The Bufferlands is a wildlife habitat refuge for endangered species and is maintained and closely monitored by seven full-time preservation biologists.
To further complicate the project, the pipeline had to extend under an existing rail line and to cross over a regulated levee. New pipeline construction would have required encroachment and environmental permits with numerous agencies. Such permits typically result in long schedule delays and additional expenses.
The Solution
The customer’s final solution was to pull FlexSteel 8-inch spoolable pipe through existing storm drains. This pipe-in-pipe rehabilitation approach allowed them to avoid earthwork and excavation in environmentally sensitive areas. This method prevented negative impacts on endangered species living in the protected areas and also helped avoid issues with encroachment permits for the adjacent rail line and levee obstacles.
The Result
Pipeline rehabilitation using the pipe-inpipe methodology was a success and was installed in a fraction of the time that would have been required for installing a completely new pipeline. Not only did this dramatically reduce costs, but it also minimized disruptive impacts to the environmental wetlands area.
Accolades Received
Subject to audits from the state, this project received positive comments from the state on how well it was
managed and subsequently won the following awards:
2022 American Public Works Association (APWA) Sacramento Chapter Project of the Year Award
2022 American Council of Engineering Companies (ACEC) Merit Award
To accommodate surface access limitations, the FlexSteel pipe was designed to enter the storm drain system via existing manhole covers. FlexSteel recommended a unique installation orientation to aide insertion and ensure product integrity to achieve this tight installation clearance.
Photo courtesy of Sacrament Regional County Sanitation District
(https://brownandcaldwell.com/2022/05/echowater-program-wins-multiple-awards/)