Layne Christensen Co. and Owen and White Consulting Engineers Inc. have received an Outstanding Groundwater Project Award from the National Ground Water Assn. for outstanding engineering and innovation in supplying groundwater.
This award will be presented during the 2015 Groundwater Expo taking place in Las Vegas, Dec. 15 to 17.
Layne Christensen of Bloomington, Ind., and Owen and White of Baton Rouge, La., designed and constructed an innovative, sustainable infrastructure project for the Baton Rouge Water Co. to mitigate the impact of saltwater intrusion into one of the city’s primary wellfields.
Saltwater intrusion is a growing concern for water utilities located in coastal regions of the United States. In some localities, brackish water contamination has forced the closure of wellfields, resulting in pumping moratoriums and expensive infrastructure to maintain hydraulic barriers. While desalination is an option, treatment systems require significant capital and are expensive to operate. Moreover, disposal of the waste stream produced by desalination can be costly.
The constructed project relies on two “scavenger” wells that achieve in situ separation of brackish water and freshwater due to the hydraulic interference between the wells.
Application of the scavenger well couple is dependent on stratification in the aquifer. In the 1,500-ft Sand Aquifer, brackish water is present at the bottom of the aquifer and overlain by high-quality freshwater. During conjunctive operation, the upper well screen provides freshwater for supply while the lower screen removes brackish water for disposal or treatment. The screen settings and the relative pumping rates of the two wells were designed such that the entire aquifer thickness is removed without vertically displacing the interface between freshwater and brackish water.
Scavenger well couples have been successfully demonstrated at select locations around the world as a practical tool for managing saltwater intrusion. However, it is believed that the scavenger well system in Baton Rouge is the only public water-supply application in production in the United States.
Source: National Ground Water Assn.
