Round Rock working to find source of significant increase in wastewater flows
The City of Round Rock announced Friday that the Brushy Creek Regional Wastewater System Treatment Plant, located along Highway 79 in Round Rock, is experiencing a significant increase in the amount of wastewater it is receiving, putting the plant above its permitted discharge levels for volume of wastewater.
The City, which operates the plant on behalf of a regional partnership, is currently working with the Texas Commission on Environmental Quality (TCEQ) to test for other areas of potential non-compliance, including total suspended solids and E. coli. Pending the results of those tests, the City will issue further guidance on public use of Brushy Creek immediately downstream of the plant.
The issue is limited to the wastewater plant only, which is jointly owned by the Cities of Round Rock, Cedar Park, Austin and Leander; the public drinking water supply is not affected.
Sporadic increases in the volume of influent, or wastewater entering the plant, were first noted by City wastewater operators in May 2021. During peak hours, organic solids called “total suspended solids” were pushed through to Brushy Creek from the plant’s clarifiers. City staff has been inspecting the water in Brushy Creek on a daily basis to ensure compliance with TCEQ standards, and TCEQ officials have visited the plant several times to confirm compliance. The City had previously stayed within acceptable discharge permit levels; however, the plant’s intake levels have dramatically increased in the last week, averaging approximately 22-24 million gallons per day (MGD), with peak flows as high as 32-33 MGD, compared to an average of approximately 18-19 MGD prior to May 2021.
Based on ongoing sampling throughout the region’s underground wastewater delivery system, which includes approximately 600 linear miles of wastewater lines, the City believes the influx of influent entering the plant is occurring as a result of inflow and infiltration (I&I), or groundwater and surface water inadvertently entering the sewer system.
The City of Round Rock is taking the following actions to find the problem and create more capacity to handle the increase in influent:
· Inspecting the underground regional wastewater infrastructure to identify the significant source of inflow and infiltration by viewing the lines with a specialized camera.
· Contracting with a third-party company to mobilize on Monday to inspect wastewater line segments within the larger, 42-inch interceptor along Hairy Man Road and Brushy Creek Road. This segment showed discrepancies in ammonia content during the City’s sampling – a possible sign of significant water infiltration.
· Working with partner cities to conduct inspections of their collection systems.
· Temporarily bringing an additional older plant back online to divert 1.7 MGD of wastewater from the main regional plant to enhance treatment capacity.
· Along with its partner cities, continuing a planned expansion that is currently under construction, which will increase the treatment plant capacity to 30 MGD. The plant expansion will be completed in summer 2023; however, new infrastructure will come online in the next six months to provide more plant capacity.
Utilities and Environmental Services Director Michael Thane will provide an update to Round Rock City Council at its regularly scheduled packet briefing at 7:30 a.m. on Tuesday, March 8 at City Hall, 221 E. Main St. A public comment period will be available at that time.
“We are working diligently to reach a resolution to this matter, and our top priority right now is finding the exact location of where groundwater or surface water may be entering the system,” Thane said. “Our wastewater treatment plant operators have decades of experience working in treatment plants, and they are working around the clock through numerous challenges to reduce our impact on Brushy Creek.”
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Source: City of Round Rock