MIAMI VALLEY — Although the rain may have stopped, MCD staff continues to monitor river levels, taking the necessary steps to keep the protected riverfront cities safe from flooding from the Great Miami River.
Staff has been closing floodgates as necessary; and monitoring levees, dams, and relief wells. The flood protection system is working as designed, says Kurt Rinehart, MCD chief engineer.
Floodgates protect cities
Storm sewers allow water to run off city streets into the river. As the river rises, however, MCD closes floodgates on the storm sewers to prevent the river from flowing back into the storm sewer system and potentially flooding areas protected by a levee.
“We receive calls from people concerned that closing the floodgate will potentially flood their neighborhood somehow,” Rinehart says. “It’s important to remember that closing a floodgate has no impact on river levels, MCD dams or the floodplain. The only impact is the prevention of river water backing up into a city if we didn’t close a floodgate.”
MCD staff closed floodgates in several cities. Among the lands protected by the floodgate closures were:
• Residential and industrial areas north of Ash Street and east of Main Street in Piqua.
• Hobart Arena and Troy City Park in Troy.
• Residential and industrial areas near Soldiers Home Road in West Carrollton.
• A commercial area at the south end of Middletown.
• Miami University Hamilton Campus and an industrial/commercial complex in Hamilton.
Relief wells flowing at two dams
Relief wells are flowing at Englewood and Taylorsville dams as expected given the amount of rain. Relief wells were installed at all of the dams to address underseepage, a vulnerability that wasn’t known when the dams were built.
When water rises behind the dams during high-water events, it creates a pool of water that puts pressure on groundwater, causing it to flow under the dam. Without relief wells, that can lead to erosion and piping in the dam, creating voids, which over time could become larger and lead to dam failure.
The project to address underseepage at Englewood Dam was completed within the last year.
“Flow in the relief wells tells us the wells are functioning properly and are relieving water pressure in the dam’s foundation, making the dam safer,” Rinehart says.
All five of MCD’s dams – Germantown, Englewood, Lockington, Taylorsville and Huffman — are storing floodwaters. Storage at the dams begins when the water rises above the conduits (concrete openings) at the dams.
Floodwater storage at each of the dams as of 12:30 p.m. today.
• Germantown Dam: 29.65 feet (storage begins at 12 feet; top of the dam is 106 feet)
• Englewood Dam: 41.77 feet (storage begins at 11.5 feet; top of the dam is 120 feet)
• Lockington Dam: 25.99 feet (storage begins at 12 feet; top of the dam is 78 feet)
• Taylorsville Dam: 21.25 feet (storage begins at 15 feet; top of the dam is 77 feet)
• Huffman Dam: 12.17 feet (storage begins at 11 feet; top of the dam is 73 feet)
Water levels in the retarding basins behind Germantown and Lockington dams have peaked. Water levels at Taylorsville and Huffman dams are expected to peak later today while water levels at Englewood Dam are expected to peak tomorrow.
The MCD flood protection system is designed to protect to the 1913 flood level plus 40 percent. During the Great Flood of 1913, the region received between 9-11 inches of rain between March 23-25.
The MCD retarding basins behind the flood-protection dams collectively have stored floodwaters more than 1,800 times, protecting communities along the Great Miami River — from Piqua to Hamilton. The integrated system of five dry dams, retarding basins, 55 miles of levee and thousands of acres of floodplain was completed in 1922. When not storing floodwaters, the land behind the dams is used as parkland and farmland.
Recent rain has caused the Great Miami River to drench the area of the levee and Treasure Island Park during the last several days. Rain is expected to come to an end which will allow work to continue on the project once the flooding has receded.