Black River Sanitary Sewer Storage Tunnel

Project Overview

NTH was chosen by ARCADIS to provide geotechnical and tunnel engineering services for a nearly 200 feet deep, 7.600 foot long, 29-foot diameter rock tunnel, including a two-phase geotechnical and hydrogeologic investigation, design of the temporary and permanent liner systems for the tunnels and shafts, preparation of technical specifications, and opinions of probable construction costs.

NTH assisted ARCADIS and the City of Lorain with initial route planning for the tunnel. Based largely on NTH’s advice and input from the City, the team chose an alignment which maximized the use of the City’s existing easements and eliminated crossings under the Black River.

Project Scope

NTH completed a two-phase geotechnical investigation which included over 900 lineal feet of soil drilling and 1,300 lineal feet of rock drilling. Inclined borings to intercept vertical fracture features in the bedrock were performed, along with in situ permeability tests using packer assemblies, an aquifer testing program, and a long-term groundwater level and explosive gas monitoring program.

NTH performed nearly all soil and laboratory testing in our Cleveland laboratory facilities. Testing included Brazilian tensile strength, unconfined compressive strength, slake durability, Cerchar abrasion testing, and other standard soil and rock index tests. NTH prepared a Geotechnical Report which included the results of the tests, our interpretation of soil and rock behavior, and practical construction considerations, such as anticipated groundwater infiltration.

While the field investigation was still underway, NTH began designing the primary and secondary lining systems for both the tunnel and the shaft structures as well.

Client Benefit

NTH utilized our tunnel and underground engineering experience to help the City of Lorain choose an optimal alignment to minimize risk and maximize future high value land development opportunities. The mining of the 7,600 foot long, 29-foot diameter tunnel was completed without a single differing conditions claim.