Lake Red Rock is in Marion County, Iowa, approximately 4 miles southwest of Pella, Iowa. During summer 2008, Iowa’s largest lake, Lake Red Rock on the Des Moines River near Pella, experienced record flood levels while holding back water to reduce downstream flooding.
This flooding caused damage to several facilities around the lake, including North Overlook Beach and Marina Cove. In 2010, Hanson was selected by the U.S. Army Corps of Engineers Rock Island District to plan the restoration and redevelopment of both facilities, including substantial facility upgrades for both.
The North Overlook Beach study included conceptual design of a new beach and numerous associated facilities, including a restroom and concession stand building, a fee booth and entrance station, a sanitary sewer pumping station, utility extensions for water and electrical utilities, the extension of a bike trail, new and reconstructed parking facilities, a new entrance roadway, surface grading and detention, campsite improvements, armoring of the shoreline to prevent future erosion damage and landscaping improvements.
Geotechnical, surveying and environmental
Hanson provided geotechnical engineering, topographic and bathymetric surveying, as well as environmental services for Marina Cove, including preparation of a scope of work for the plans and specifications (P&S), planning drawings, a preliminary geotechnical investigation and a project cost estimate for each project feature.
The intent of the preliminary geotechnical investigation was to provide sufficient data to allow preliminary project feature design. Hanson performed preliminary subsurface exploration and laboratory testing to provide sufficient general subsurface data for the project area. The preliminary subsurface exploration and laboratory testing program enabled the project feature design engineer to make reasonably accurate assumptions regarding bedrock elevation and sediment and foundation characteristics (including foundation soil strength) relative to the potential types and possible locations of the proposed project features.
Hanson performed four general borings and one sediment bucket sample at the site. General borings included exploration, testing and sampling with split-spoon. Field logs, samples, computer-generated logs (including raw data from gINT electronic files) and lab test results were delivered to the Rock Island District Geotechnical Branch office, along with representative soil samples.
Hanson conducted sediment sampling to assess lake sediments for potential contaminants prior to dredging and prepared a work plan for approval by USACE, collected sediment samples from the lake bottom, coordinated laboratory analysis and provided a report of the sampling methodology and analytical results.
