Westerly Low-Level Relief Sewer

Project Overview

To comply with their Consent Decree with the Environmental Protection Agency (EPA) mandate of reducing sewage overflow into Lake Erie, the Northeast Ohio Regional Sewer District (NEORSD) retained NTH Consultants, Ltd. (NTH) as Prime Engineer for design of a relief sewer / storage tunnel along River Road and Elm Avenue in Cleveland, Ohio. The Westerly Low Level Relief Sewer (WLLRS) Project includes regulator modifications, up-sizing of dry weather outlet (DWO) sewers, and approximately 2,600 lineal feet of new 72- inch diameter relief/storage sewer with relatively shallow depths of 8 to 25 feet. The project also includes new regulators connecting to the existing interceptor that ties into the pump station, pump station modification design, force main design, and local sewer stormwater offloading design.

The NTH team worked closely with NEORSD to address design issues and constraints for the project and was instrumental in selecting a viable project location and proposed construction methods. NTH worked with subconsultants AECOM and KS Associates to develop various design options and alignments. NTH conducted a geotechnical investigation along the project alignment consisting of soil borings, monitoring wells, laboratory testing, and performance of slug testing. With the most feasible alignment located primarily in loose lacustrine soils, the geotechnical evaluation proved to be an instrumental portion of the project.

Project Scope

NTH was able to lead a design effort of this project that included value engineering to add additional improvements while simultaneously lowering the anticipated construction costs. NTH assisted with bid reviews and is currently performing construction reviews. NEORSD has been pleased with NTH’s timely responses to meet deadlines, overall project management and professional deliverables.

Client Benefit

NTH’s multidisciplinary engineering management expertise served as a critical aspect to completing this project successfully, due to the changing project components and developments requested.