Client:
  • Northeast Ohio Regional
  • Sewer District

Location:
  • Cleveland, OH

Prime Consultant:
  • NTH Consultants, Ltd.

Subconsultants:
  • MWH Americas, Inc.
  • KS Associates, Inc.
  • DLZ Ohio, Inc.
  • Ohio Testbore, Inc.

Project Budget / Final Fee:
  • $722,400

Contract Start Date:
  • March 2006

Contract Completion Date:
  • April 2008

Westerly Low Level Interceptor Emergency

Investigation and Repair of a Distressed Sewer

In February, 2006, a portion of Riverbed Street, on the west bank of the Cuyahoga River, failed due to movement of the adjacent riverbank slope. The Northeast Ohio Regional Sewer District (NEORSD) immediately engaged NTH Consultants, Ltd. (NTH) to investigate the sewer and design a temporary support system. During construction of the support system, a second portion of the same sewer was threatened at a point further upstream, also by a slope failure.

Scope of Work
NEORSD retained NTH and an underground contractor to perform an emergency investigation and to immediately design and install a stabilization system. NTH and the emergency contractor worked with NEORSD directly to assess existing conditions and stabilize the situation.

Our tasks included:
  • A utility investigation using geotechnical drilling methods to locate the as-built pipe centerline
  • Design, installation, and monitoring of geotechnical and survey monitoring systems to assess on-going movements of the slope and sewer pipe
  • Design of a temporary construction shaft and stainless steel / concrete  support system to allow safe penetration of the sewer’s brick lining
  • Multiple confined space entries and conditions surveys to delineate the areas of greatest distress
  • Design of a rib and lagging bracing system to provide short-term bracing
  • Review of historical geotechnical investigations and completion of new slope stability analyses to determine the likely cause of the sewer distress and slope failure
  • Research and identification of possible funding sources for repair of the sewer and slopes
  • Evaluation of multiple temporary rehabilitation options, including CCFRPM, HDPE, DIP, CIPP, and spiral-wound PVC systems. Recommended and designed innovative spiral-lining system to provide longer-term bracing to the tunnel
  • Design of new manhole structures, including stop log systems designed to give NEORSD flexibility for future operations
  • Review of all contractor submittals for compliance with design intent
  • Creation of as-built drawings for the project
  • Assistance to NEORSD during meetings and negotiations with local, city and federal agencies