The EchoWater Project, an approximately $2 billion plant expansion includes subdividing the 60-acre Flow Equalization Basins, deepening the basins by 10 feet, and lining the basins with concrete.  These basins are adjacent to and separated from Beach Lake-a tributary of the Sacramento River-by a levee that is part of the South Sacramento Stream Group Project Levee System, incorporated by the U.S. Army Corps of Engineers (USACE) in the 1990s.  These levees fall under jurisdiction of the Central Valley Flood Protection Board (CVFPB).  The embankments bounding the north and south sides of the basins are also a regulated dam under the jurisdiction of California Division of Safety of Dams (DSOD).

As part of its studies for the Flow Equalization Basins, Shannon & Wilson performed extensive groundwater modeling to design the underdrain system beneath the liner, which would extend below the seasonal top of groundwater. Shannon & Wilson analyzed stability and seepage, both as a levee with water on the north side and as a dam with water on the south side, to meet regulatory criteria, and performed 3D settlement analyses as the pipelines and their connections to structures are settlement sensitive. Shannon & Wilson is currently providing engineering services during construction, including observing construction of critical elements, evaluating construction dewatering, and reviewing geotechnically-related RFIs and submittals.