Geotechnology engineers working at project site

Western Regional Sanitary Sewer

Location: Boone County, Kentucky

Client: HDR/Quest Engineers

Services: Geotechnical


Geotechnology was a geotechnical member of the design team for the Western Regional Conveyance Project in Boone County, Kentucky. The project included 32,574 feet of 9.5-foot diameter tunnel ranging from 35 to 300 feet below the ground surface. This included 702 feet of aerial, bridge-supported sewer as high as 43 feet above the ground surface. This also consisted of 2,918 feet of 8.5-foot diameter open-cut sewer as much as 30 feet below the ground surface.

Western Regional Sanitary Sewer Project Background

Project engineering responsibilities included the attending public meetings, logging the rock core and documenting geologic discontinuities such as faults, joints, and deep sand seams. We also determined the Rock Mass Rating (RMR) for the geologic formations of interest and managed an extensive in-house and out-sourced laboratory test program

The project consisted of evaluation of regional seismicity, site class, seismic design category, liquefaction potential, and seismic densification potential, design of a wick drain system to accelerate embankment settlements and design of deep foundations for the bridge structure. in addition, we estimated long-term, open-cut sewer pipe settlements and conducted geologic field mapping.

This complex project also required an extensive geophysics program to define the bedrock/overburden contact in key areas of the driven tunnel alignment and interpretation of complex geologic overburden profiles in glaciated deep valleys. Additionally, we constructed geologic cross sections and foundation design for ancillary structures as well as produced the Geotechnical Data Report (GDR). We also provided assistance to the tunnel/bridge designer in assembling the Geotechnical Baseline Report (GBR). Finally, we worked extensively with the Tunnel Review Board (TRB) and reviewed the plans and specifications.

*Services were provided by Thelen Associates, Inc.