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Heavy rainfall on Feb. 24 and 25 caused four separate wastewater overflows from the Trinity River Authority (TRA) of Texas' Elm Fork collection system.
Wastewater lines are customarily built adjacent to streams, on this occasion the Elm Fork of the Trinity River, to enable wastewater to flow by gravity to treatment facilities. When rainfall and floodwater cover collection lines and manholes, water is able to enter or infiltrate into the collection lines. Overflows occur when the combined volume of wastewater and rainfall exceed the capacity of the line.
The impact was minimized on this occasion by the volume of floodwater in both the collection line and the Elm Fork of the Trinity River, which ultimately received a portion of the wastewater overflow.
Overflows occurred in three locations in Irving and one in Grand Prairie immediately adjacent to TRA's Central Regional Wastewater Treatment Plant. The first three overflows upstream of the treatment facility occurred from approximately 9:30 a.m. on Saturday, Feb. 25 until 6:00 a.m. on Sunday, Feb. 26. At each of these locations, an estimated 141,000 gal of wastewater was discharged from the collection line and ultimately entered the Elm Fork of the Trinity River.
The first Irving location was from a lift station in the vicinity of Century Boulevard and International Parkway. The second was from a manhole in the vicinity of SH-183 and Grauweyler. The third was from a meter station at the end of East Proctor Road east of Union Bower. Planning, design and construction is underway to provide better service to facilities in this area.
The overflow in Grand Prairie immediately adjacent to the treatment plant was fully contained in a large pit that had been dug as part of a construction project that is underway. The overflow from a junction box on the east side of the treatment plant took place from approximately 6 a.m. on Saturday, Feb. 25 until 4:30 a.m. on Sunday, Feb. 26. It was possible to ultimately return all of this overflow, an estimated 1.2 million gal, to the treatment plant for processing.
No public drinking water supplies were threatened or contaminated by any of these overflows. The Texas Commission on Environmental Quality requires all wastewater overflows in excess of 100,000 gal to be reported to the commission, the public and other designated public officials.