The Oakland-Macomb Interceptor Drain (OMID) is a large diameter deep sewer system that serves over 800,000 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. 

Nearly ten years ago, 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 six (6) construction contracts that comprised the overall rehabilitation and repair program. 

Throughout the years, NTH has won numerous awards for our work on this project including:

​​​​Many years later, the OMID team gathered on May 23 at the site of Control Structure 3 for a ceremonial ribbon cutting to commemorate the substantial completion of the OMID repair program - a milestone over 10 years in the making!

​On hand for the ceremony were Macomb County Public Works Commissioner Candice Miller, Oakland County Water Resources Commissioner Jim Nash, several key members of both counties’ staff, representatives of Jay Dee Contractors, and the engineering team led by NTH.  Representatives from the Owner, Contractor, and Engineering team spoke about the successful project, and the team celebrated with a luncheon following the proceedings.

By Ryan Butler, P.E.

The NTH Cleveland office has been receiving requests for their Subsurface Utility Engineering (SUE) expertise more and more frequently.  One of the more recent requests occurred on the Doan Valley Relief and Consolidation Sewer (DVRCS) project, on which NTH is conducting various geotechnical field and design tasks.  NTH was asked to locate the alignment (horizontal and vertical) of a No. 7 brick sewer that was installed in the 1920s.  As you can imagine, as-built documentation was relatively non-existent, and so there was a blind bend in the pipe – meaning a bend that occurred where no access structure is located (e.g. manhole). After looking into our options, and including relatively new innovative ideas, we determined this type of SUE effort would require a two-step approach. 

The first step required narrowing down the horizontal alignment.  This type of challenge is not new to NTH, as we have traced sewers through various means of inserting traceable equipment into the pipe.  For this particular instance, we were dealing with a sewer that was on the order of approximately 20 to 25 feet in depth – where the traceable device would feasibly be located. A depth of 20 feet is generally considered the assumed feasible maximum depth for tracing with line locators; however, we have traced deeper objects in the past, so we knew it could be done – especially with assistance of newer tracer wire that was in good (non-corroded) shape. 

With assistance of our subcontractor, we pulled our tracer wire through the sewer by use of a CCTV rover. This produced mixed results, as we seemed to be receiving interference in tracing signal from objects other than our target tracer wire.  It did not help that the area is relatively congested with underground utilities, but we did not believe this to cause as much issue as we were having.  We thought maybe we were receiving interference form the CCTV unit due to our tracer wire being located so closely to electronics.  Thankfully, the No. 7 brick sewer carried relatively high flow and our field engineer, Anthoni Fazio, came up with the innovative idea of creating a flotation object to carry the tracer wire which allowed us to avoid the potential CCTV interference and made the attempt more cost effective. We converted a plastic cleaning device bottle into a perfect floatation object that got the job done.  The tracing seemed to work well and produce results we were confident with.
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Then we were on to step 2 which involved exploratory drilling to touch the top of the brick sewer at a number of locations and confirm its profile.  We were able to work around some ‘hiccups’ with this step as well, use our decisive engineering judgement, and produce the results needed!

Project Overview:
The Oakland-Macomb Interceptor Drain (OMID) is a large diameter sewer system that serves over 800,000 residents of Oakland and Macomb Counties. This sewer was constructed in the I970s, and has experienced several catastrophic collapses over its service life, the latest occurring in 2004. The OMID system consists of mostly 8-foot to I 3-foot diameter sewers that are up to 110 feet deep, extending below major transportation and power transmission corridors, which serve several million people and businesses. 

NTH performed several inspections in 2005 through 2008, and found that many areas of the sewer were in poor condition and could be subject to additional collapses. The OMID Board chose NTH to lead a team of design consultants and develop an approach for rehabilitation of the system, and to prepare contract documents for three-phase rehabilitation and repair program. Segment 3 (Contract 4) of the program began construction in November, 2013 and was substantially completed in July, 2016.  

​This segment of the OMID Repair Program was a first for our industry in many ways. Never before had a repair program been attempted at such a large diameter (up to 13 feet), at such extreme depths (up to 110 feet), at these lengths (over seven miles), without the ability to bypass flow. This unprecedented scope of construction required complex flow control systems; innovative construction means, methods, and equipment; and efficient operations in tight work windows. Because of the truly unique nature of this project and the challenges involved in its successful completion, Segment 3 of the OMID Repair Program has garnered national attention in our industry.