DETROIT WATER AND SEWERAGE DEPARTMENT ROMEO ARM OF THE MACOMB SEWER INTERCEPTOR August 30, 2004 Update The break in the 11-foot diameter sewer interceptor below 15 Mile Road at Fontana Drive in Sterling Heights was discovered on Sunday morning, August 22, 2004. An interceptor is a large sewer main that receives flows from many other lines, but has only one outlet. The Romeo Arm of the Macomb Sewer Interceptor has a flow capacity of 30-60 million gallons a day. WHAT HAPPENED At approximately, 2 a.m. on August 22nd, the Sterling Heights Police Department reported water on 15 Mile Road and a slight sinking of the pavement. The water on the road was the result of a broken 8-inch water main. The water main was shut and some residents were temporarily without water service while water was being rerouted. Pavement near the water main break continued to collapse and it was then determined that there was probable damage to the sewer interceptor located approximately 60-feet below ground. WHY DID IT HAPPEN DWSD does not know at this time when specifically the break in the interceptor happened or the extent of the damage incurred. The damage is believed to have occurred no later than August 21st. The depression created by the damaged interceptor is about 40-feet deep and the interceptor itself is not exposed. It will take some time to determine the cause. WHAT IS KNOWN AT THIS TIME A break of undetermined origin and size occurred to the sewer interceptor located approximately 60-feet beneath the street surface. Leakage from the broken interceptor caused the surrounding soil to fall into it, and be carried toward the Detroit Wastewater Treatment Plant. As more and more of the surrounding soil continued to fall into the interceptor, a bigger and bigger empty space was created. Eventually, soil supporting the water main located closer to the surface of the ground gave way, which is the probable cause of the broken water main that alerted crews to the bigger problem farther below. The loss of soil beneath the street level is what caused the sinkhole that formed at the site. As a safety precaution, six homes on the south side of 15 Mile Road were evacuated because of the extent of the ground collapse, so that power cables extending over the area could be taken out of service and other utilities rerouted. Residents were allowed to return to four of the homes on Tuesday, August 23rd and to the last two homes on Friday, August 27th. WHAT IS NEXT DWSD, to this point in time, has concentrated on stabilizing the sinkhole and appears to have stopped the hole from growing any larger. Currently, work crews are constructing a bypass around the damaged portion of the interceptor. A 6-foot diameter pipe, fed by three pumps, will route sanitary sewage flow from the damaged section and return it to the interceptor west of the damaged section. Unfortunately, because of the nature of the repairs, it will be necessary to maintain the bypass in place for several months. Once the temporary bypass is in place, bulkheads in the interceptor will be closed to isolate the damage. Before repairs can be performed, the extent of the actual damaged sustained by the sanitary sewer must be determined. This will be done by a sending a remote television camera down into the interceptor to videotape the damage. The department will also televise the 1,000 feet before and after the break to ensure that there are no additional trouble spots. Once the nature of the damage is known, the best repair method can be determined. It needs to be understood that the ground area immediately surrounding the damage must be completely de-watered before any repairs can begin. DWSD intends to minimize, as much as possible, any inconvenience to Sterling Heights residents while making the necessary repairs. This site will be updated as necessary in order to keep our customers fully informed of progress. Click image for a larger version back to Macomb Interceptor Information
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