- Geotechnical investigations
- Floodplain permitting
- Alternatives evaluation
- Spillway design
- Pipeline and pump station design
- Slope modifications
- Surface water collection facilities
- Construction documents
- Resident engineering
- Construction administration services
The West Sprat Platte Reservoir is a gravel pit was originally mined for sand and gravel in the 1970s and 1980s. The City of Thornton (Thornton) acquired the gravel pit in 2001 with the intention of converting it into a lined water storage reservoir. At the time the gravel pit was acquired, it was lacking all of the major components required for use as a water storage reservoir including a groundwater liner, hydraulic infrastructure, stable reclamation slopes, and a spillway.
The site is in a highly constrained area, with existing facilities on each side of the reservoir that include wetlands, public park facilities, fishing facilities, water lines, sanitary sewer, high voltage transmission lines, a two-lane road, and the South Platte River. The reservoir is located within the South Platte River 100-year floodplain and is at risk of being flooded, which could cause a breach of the berm between the river and the reservoir.
RJH was retained by Thornton to assist in developing a comprehensive design and construction program to convert the gravel pit into a water storage reservoir. RJH identified key project constraints and issues, and through an extensive alternatives’ analysis, developed and selected improvement concepts for design of the project. To support development and selection of the alternatives, RJH collected geotechnical data for both foundation soil and bedrock, hydrologic data, wetland delineations, pedestrian traffic data, and Thornton’s preferences for aesthetics and functionality.
The project was implemented in two phases. Phase 1 included a perimeter seepage barrier wall, groundwater control drain, two pump stations, and a multi-use trail. Phase 2 included the grading of interior reservoir slopes; developing an area for fish habitat along the bottom of the reservoir; and installation of a riverside spillway, interconnect pipelines to adjacent reservoirs, surface water collection facilities, and fishing and boating facilities. RJH provided design and construction engineering services for both phases of design.