Deeds Point & Triangle Park Sanitary Sewer Siphon Improvements

Design completion: May 2015
Construction completion: January 2016
Client: City of Dayton, Department of Water, Division of Water Engineering

Project Overview

Ribway was selected as the prime consultant to provide professional engineering services for rehabilitation of these two sanitary siphons that cross the Great Miami River in Dayton, Ohio. The City embarked on this project to rehabilitate the deteriorating siphons that were constructed in the late 1940s.  Each siphon crossing comprised of buried upstream and downstream flow control concrete chambers. The Deeds Point siphon has three 480lf cast iron pipe barrels, two (2) 30-inch and one (1) 36-inch diameter. Triangle Point has two 400lf cast iron pipe barrels, a 30-inch and 36-inch diameter.

Ribway’s scope of services included:

• Field investigations of the existing siphon chambers
• Field survey
• Geotechnical investigations
• Visual condition assessment of the concrete siphon chambers
• Sonar investigations of the siphon barrels
• Hydraulic analyses
• Preparation of a design report summarizing the existing siphon conditions
• Alternatives for rehabilitation and associated costs
• Preparation of detailed plans and specifications
• Part time engineering services during construction

The siphons are located within the 100-year flood plain of the Great Miami River and the design was coordinated with the Miami Conservancy District to minimize disruption to the recreational paths along the river and the flood control embankments. The design included:

• Evaluation of rehabilitation alternatives and concrete rehabilitation materials
• Hydraulic analysis of the existing siphon crossings
• Determination of river flood elevations
• Bypass pumping flow requirements (10.5 MGD @ Triangle Park and 14.8 MGD at Deeds Point)
• Sedimentation and erosion control plans

Plans and specifications were prepared to replace the top slabs of all four siphon chambers with cast-in-place construction and rehabilitation of the interior concrete surfaces of all four chambers, including:

• Removal of interior stop plate guides
• Manhole steps
• Abandonment of clean-out chambers
• New access openings with sealed covers were provided in the new slabs

The rehabilitation of siphon barrels included:

• Cleaning
• CCTV inspections
• CIPP lining.
• A pre-liner was also used before final CIPP lining

Contingency items were developed for mechanical and CIPP pipe repair sleeves, and cementitious and chemical grouting of structures.