Keith Lumma, AEW Engineering Aide III, Candice Miller, Macomb County Public Works Commissioner, and AEW President and CEO Roy Rose discuss progress at the site on March 1 following the significant rain event we had the previous evening, The good news is that despite the area receiving almost two inches of rainfall overnight, Public Works employees and contractors were able to control the flow through and around the damaged interceptor, and no untreated sewage was pumped into our waterways.
Long-term bypass pumping installation is nearing completion, signage for motorists and businesses is in place, and the length and width of the sinkhole seems to be contained thanks to the positive impact of compaction grouting. Dewatering wells are doing their job, with groundwater levels and the resulting pressure on the interceptor pipe significantly reduced, and steel is arriving that will be used in the construction of the shaft that will enable contractors to reach the damaged interceptor and begin the repair process.
The sinkhole “chimney” continues to grow in front of this condemned home on 15 Mile Road. The rain event overnight on March 1 contributed to the erosion at the site.
70-ft., 13,000 pound steel beams arriving on site from Steel Dynamics located in Columbia City, Indiana. The beams will be used in the construction of the shaft that will allow access to the collapsed interceptor. The shaft will be approximately 300 feet long, 30 feet wide and 60 feet deep.
Chris Frayer, AEW Graduate Engineer, explains the shaft construction: “Part of the shaft construction is a Temporary Earth Retention System (TERS) consisting of primary and secondary 36” piers and steel bracing. The 3 foot diameter piers are drilled then filled with concrete. The primary piers have steel H-Piles (the steel the County has purchased that is being delivered) and the secondary piers do not have H-Piles. The piers surround the shaft to hold the earth back because the excavation is so deep. The steel bracing is a bid item and will be procured by the contractor that is awarded the work. The steel bracing is attached to the H-Piles in the primary piers. The H-Piles are needed sooner than the steel bracing in the sequence of construction. The County purchased these in advance to reduce lead time and help expedite the work.”
This manifold, located on the northeast corner of 15 Mile at Hayes, serves as the inlet for the twin 48” pipes that originate at “Control Station #3” on the south side of 15 Mile, approximately 150 yards west of Garfield. One of the pipes is currently in place, and the other will soon follow; the outlet side of the manifold connects to a 54” pipe (shown below) that crosses Hayes to the west above ground, and then goes under 15 Mile to the south, and follows 15 Mile above ground to Fontana drive where it dumps into a manhole, effectively bypassing the damaged section of the 11’ diameter interceptor.