The Trinity River Authority (TRA) has reported the inadvertent outflow of wastewater from its Kirkwood Branch Lift Station that transports wastewater originating in Southlake, Texas, to its Denton Creek Regional Wastewater System (DCRWS) treatment plant in Roanoke.
The Feb. 15 outflow is a result of the failure of the pumps in the DCRWS's Kirkwood Lift Station causing wastewater to back up into the pipeline system and flow out of a nearby manhole located on Kirkwood Branch north of Highway 114.
Debris, including two-by-fours, is suspected to have contributed to the failure of the pumps' drive shafts. Analysis and repairs of the equipment will be performed. The lift station's multiple pumps were intended to provide redundancy and reliability.
TRA employed pump trucks to move as much wastewater as possible from the lift station and vicinity of the outflow to gravity flow segments of the pipeline system closer to the wastewater treatment plant located off of Highway 377 north of Roanoke. In addition, a contractor was mobilized to construct a temporary earthen berm downstream of the outflow to contain and minimize flows to downstream areas during the event.
The lift station normally moves wastewater generated in Southlake through a pressure line to gravity flow segments of the collection system that lead to the treatment plant.
TRA estimates that 205,000 gallons of wastewater flowed out into Kirkwood Branch that enters into the Kirkwood Branch drainage cove before entering Grapevine Lake. The undesirable event is not expected to have any impact on water quality in the lake.
Follow up water quality sampling of the creek, cove and lake is underway. TRA will complete a remediation of the area that could potentially be impacted by the wastewater spill as part of the repair of the pump station.
The Texas Commission on Environmental Quality has been notified of the spill and TRA has initiated efforts to contact all entities that depend on Lake Grapevine as a public water supply.
TRA replaced one of the lift station pumps before midnight on February 15 and resumed normal operations.