Drain Inspections Under I-696
The Office of the Macomb County Public Works Commissioner (OMCPWC) contracted with Spalding DeDecker (SD) to inspect two County drain crossings under the I-696 freeway in Macomb County to determine the level of sediment in the drains and the condition of the drains.
Schoenherr Relief Drain
The Schoenherr Relief Drain was in service prior to the construction of the I-696 freeway. As part of the freeway construction, the section of the 14.5’ x 14.5’ box drain underneath the proposed freeway was removed, and the flow was rerouted through three 9’-6” W x 7’-6” H box sections.
Based upon a previous inspection of the drain, there was evidence that over the last 30 years, sediment had been accumulating in the three smaller box sections, impeding the flow of storm water and drainage.
SD personnel entered the drain and physically inspected the three boxes measuring the sediment depth at 100 ft intervals. SD took a sediment sample for analysis. The drain inspection was performed using confined space entry procedures, with Certified Confined Space Entry & Tunnel Rescue from SD. Sewer specialists and attendants used protective clothing, full body harnesses, and Emergency Breathing Apparatuses (EBA) to complete the task.
At Dequindre Road and the I-696 freeway, 78” and 72” drains enter into a chamber upstream of the I-696 freeway. At the chamber, the flow is split into three 78” pipes that serve as a siphon to bypass under I-696. At the other end of the freeway, the three siphon pipes rise back up to the original invert elevation. The three pipes then join at a downstream chamber. Flow from the downstream chamber is discharged through the 114” diameter Sharkey Drain.
The three siphons were de-watered prior to the entry. SD personnel then entered the downstream chamber using proper confined space entry equipment and attire and walked the length of the siphon under the freeway. Sediment level was recorded at regular intervals, and a sample of the sediment was taken for analysis.