Oakland-Macomb Interceptor Drain Repair Program (OMID)
Design Services and Construction Engineering
Award of Merit for Engineering:
American Council of Engineering Companies
of Michigan (ACEC/Michigan)
The Oakland-Macomb Interceptor Drain (OMID) is a large diameter deep sewer system that serves approximately 1.2 million residents of Southeastern Michigan. This sewer was constructed in-tunnel in the 1970s, and has experienced several catastrophic failures over the years, the latest in 2004. The OMID system consists of mostly 8 foot to 12.75 foot diameter sewer that ranges in depth from 30 to 110 feet. Most of the system extends below major roadway and railway corridor, and through the ITC power transmission corridor, which provides power to several million people and businesses in Macomb County and Michigan’s thumb-area.
Based on NTH inspections in 2005 through 2008, many areas of the sewer are in poor condition and could be subject to sudden failure. There is no redundancy in the system, so any collapse would disrupt service to the entire upstream population. Further, a collapse would affect millions more in terms of disruption of major roadway, and/or power supply. Because a sewer failure would be so catastrophic to the population of southeast Michigan, this project became a top priority for the Counties, and the Michigan Department of Environmental Quality.
In May of 2009, the Oakland Macomb Interceptor Drain Drainage District selected NTH Consultants to lead a team to develop an overall design approach for rehabilitation of the system, and to prepare contract documents for the first segment of construction (initially estimated at about $60 million, later reduced to about 32 million after eliminating some of the work). This first segment was required by the MDEQ to be substantially designed by the end of July, about 10 weeks after the notice to proceed; with final completion of design 6 weeks later.
The scope of services for the design includes over 12,000 feet of geotechnical drilling, 8,000 feet of surface seismic profiling, 20 miles of sewer alignment survey, 4 full scale aquifer pumping tests, hydraulic evaluations, design of in-system flow controls, design of a 100 mgd pumping station (60 feet diameter, 90 feet deep), design of 4 major gate/access structures (25 to 35 feet diameter, 40 to 100 feet deep), Phase 1 and 2 environmental assessments, wetland assessments and permitting, easement assessments and procurement, and design for repairs to over 7 miles of sewer.