Supplement Wet Weather Investigation of Upper Rouge Outfalls

DWSD retained METCO to conduct wet weather investigation at twelve (12) Upper Rouge Outfalls to verify CSO discharge frequencies and volumes and to validate the data currently available from the DWSD metering system. It included both field investigation and flow monitoring for 12 months. Specifically, METCO provided the following services: - Review the existing drawings of the related sewer system and field investigate to determine the manhole(s) which provide the best hydraulics for installation of proposed flow sensors, both upstream and downstream of the diversion structure. - Furnished and installed twenty-nine (29) flow measuring devices necessary to determine the overflows in various outfalls within the Rouge River watershed. The flow measurement system at each location consisted of battery-powered ultrasonic flow sensors/AV meters including integral storage device with a serial port for periodic downloading of data. - Programmed, tested and calibrated flow meters consistent with the configuration of each Outfall and in accordance with the manufacturer's recommended procedures. - Downloaded flow data at every two weeks during dry weather period and immediately after each significant rainfall event. Analyze the data for the trend and correlation with the rainfall intensity. - Visual observations during or immediately after a storm event to verify the flows through the structures. - Developed in-house hydraulic model using the existing GDRSS model to establish hydrographs for each of the structures METCO conducted this monitoring for about 1 year beginning in November 2010 and was able to capture flow information for a significant number of events during the very wet 2011 season. METCO observed the flows through these structures and compared them with the river elevations and the rainfall gauges installed by DWSD. A thorough analysis was conducted using the actual data. The data was also used to modify the GDRSS model as it relates to the Upper Rouge River basin area. Significant observations and recommendations were made from the analytical outcome of the model runs using these actual field data. The report and recommendations were reviewed and accepted by MDEQ.