Our projects rely on our investigations and assessments that we perform in-house, including risk assessments; geotechnical investigations; and geotechnical baseline, data and design reports.
Interceptor Sewer System
​This 7.5-mile interceptor sewer system includes 14 tunnels of varying size and constructed under two construction phases.
They lie in both glacial outwash sands and St. Peter sandstone bedrock.
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Geotechnical exploration program and data report
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Conceptual design
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Evaluation of tunneling methods
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Tunnel and pipe design
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Geotechnical analysis & baseline report
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Geotechnical Instrumentation analysis & coordination of observations
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Construction observation & engineering
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Geotechnical Instrumentation
Tunnel Management Planning
​CNA specializes in developing management plans for tunnels and large-diameter pipelines. A unique inspection and data recording system is used to gather data that is then analyzed and evaluated. Each tunnel segment is rated for purposes of prioritizing maintenance, repairs and rehabilitation. CNA then utilizes this information to design repairs and rehabilitation methods.
Forcemain Improvements - Mississippi River Crossing
This complex project included three tunnels and a cut-and-cover river crossing for a 3-mile-long sanitary sewer in an urban area.
CNA provided the geotechnical engineering and design for the tunnels and river crossing, including grout design, plans & specifications, and construction observation.
