case study: Ojibway sanitary trunk sewer rehabilitation project
The City of Windsor’s Public Works Department is responsible for the operation, maintenance, and overall rehabilitation planning for all the storm and sanitary sewers throughout the City of Windsor. In June 2020, the city staff discovered a sink hole along the Ojibway sanitary trunk sewer. The City immediately engaged Andrews.engineer (A.E) and performed emergency inspection for the entire 2.6 km of Ojibway sanitary trunk sewer. The inspection showed that a portion of the trunk sewer comprising 7 segments (675 mm – 900 mm) totalling 650 m of sewers experienced significant corrosion with hanging gaskets and exposed rebars. All 28 maintenance holes (MH) along the entire sewer are also experiencing severe corrosion due to H2S attack.
Following the emergency inspection work, the City engaged A.E to undertake detailed design for the rehabilitation of the Ojibway sanitary trunk sewer and all associated MHs. As part of the design process, additional sewage grab sampling and H2S monitoring activities were carried out in order to further understand the root cause of the severe corrosion that was observed in order to design a lining method and material that would withstand significant H2S attack. Due to the failing condition of the trunk sewer at the sink hole location, all associated investigation, co-ordination, detailed design was performed under an extremely tight schedule.
A.E’s scope for the project includes the following:
Development of trenchless rehabilitation and localized replacement solution for seven sanitary trunk sewer segments (675 mm – 900 mm) totalling 650 m and 28 sanitary MHs that are experiencing severe corrosion
Carry out additional sewage grab sampling, H2S monitoring, pH testing and pilot cleaning activities to ensure lining is feasible
Perform detailed design with construction drawings and tender document preparation
Provide tendering, contract administration, and site inspection support throughout the entire construction phase
City of Windsor, Ontario
Pilot mechanical cleaning
Sewage grab sampling and H2S
Detailed rehabilitation design
By-pass strategy development
Specification development, Tender Package development
Contractor submittal review and contract administration assistance during construction