Laguna Wetland Restoration Project

Laguna Wetland Restoration Project: Grading, Water Control, & Water Delivery System Plan

As part of the Lower Colorado River Multi-Species Conservation Program (LCR-MSCP), the Bureau of Reclamation  undertook a 1,250 acre habitat restoration project along a historic reach of the Lower Colorado River, between Imperial and Laguna Dams, near Yuma Arizona. As part of this landscape scale project, large stands of invasive salt cedar (Tamarix spp.) that were pervasive throughout the area were removed, the site was re-contoured to optimize water use and habitat, and a mosaic of native wetland, riparian and upland vegetation was planted. Water was conveyed to the wetlands by a new water delivery system that was constructed as part of the restoration project.  Once water reaches the wetlands it is managed with a series of large automated water control structures based on seasonal habitat and wildlife needs. The resulting wetland complex is expected to attract many migratory birds and increase acreage for several threatened and endangered native birds and mammals. Construction on the project began in 2011 and was completed in 2015.

The following is a summary of George F. Cathey’s technical contribution to the project (as an employee of Natural Channel Design, Inc.):

• Engineer of Record and lead designer for all civil works associated with the restoration project.
• Permitting Assistance – Coordinated with the USBR on the Army Corps of Engineers (ACE) Jurisdictional delineation and federal NEPA compliance, and aided with the development of all documents for the ACE 404 permit and Stormwater Pollution Prevention Plan (SWPPP). Coordinated closely with USBR State Historic Preservation Office (SHPO) representatives to align the water delivery pipeline such that cultural resources from the WWII era Yuma Test Branch were not impacted.
• Water Delivery System Survey and Design – Completed all topographic corridor surveys, modeling, and analysis for a 2,600 foot long, 48-inch diameter HDPE pipeline and associated cast-in-place concrete headworks and outlet works facilities to deliver water to the wetland complex. Pipeline design included detailed hydraulic analysis, ring deflection, ring compression, & ring buckling analysis for HDPE pipe, buoyancy calculations, design for combination air/vacuum and air release valves, and design of custom fabricated fusion weld HDPE pressure manholes. The headworks design included finite element analysis and seismic analysis of the cast-in-place reinforced concrete facilities, specifications for an automated flow meter & control gate and also slide gates, and design of a custom fabricated stainless steel spool embed for the HDPE pipeline connection.
• Wetland Design – Provided all analysis for the grading and water control plan including earth balance calculations for ~1.5 million cubic yards of proposed earthwork, structural concrete calculations for cast-in-place concrete facilities designed to house the water control gates, specifications for the automated, solar powered, SCADA equipped wetland water control overshot gates, and the development of preliminary seasonal water maintenance hydrographs.
• Construction Packages – Completed and sealed the construction packages (specifications, drawings, calculations, and quantity take-offs) for the water delivery system plan, invasive species removal plan, habitat re-contouring plan, and water control structure plan.
• Revegetation Plan Collaboration – Coordinated and collaborated with Fred Phillips Consulting, Inc., as needed, as part of the development of the grading and revegetation plan.
• Client Coordination and Design Review – Acted as the technical liaison to the LCR-MSCP and provided progress reports and presentations to regional offices of the USBR that were part of the design review team.
• Contractor Collaboration – Worked closely with the general construction contractor chosen for the project during the design phase, and recommendations regarding constructability were incorporated into the final plans.
• Construction Phase Services – Provided construction administration services including observation and RFI responses.