August 2010, Vol. 22, No.8

Plant Profile

Lakeview Regional Water Reclamation Plant

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Location: City of Lake Dallas, Texas
Startup date: 1998
Service population: 54,000
Number of employees: 5 operators
Design flow: 5.0 mgd (18,925 m3/d)
Average daily flow: 3.9 mgd (14,760 m3/d)
Peak flow: 12 mgd (45,420 m3/d)
Annual operating cost: $2.3 million

Not once since its startup in 1998 has the Lakeview Regional Water Reclamation Plant (City of Lake Dallas, Texas) had a permit violation. Through 11 years of operation, including a major expansion where the headworks had to be bypassed and each of the aeration basins had to be cycled out of service, this advanced treatment plant has maintained its perfect record. The Lakeview plant is one of three regional wastewater facilities owned and operated by Upper Trinity Regional Water District.

In 2008, the Lakeview plant was recognized with the Municipal Wastewater Treatment Plant of the Year Award by the Water Environment Association of Texas (WEAT; Austin). In 2009, WEAT named the plant’s superintendent of operations, Ron Lucero, WEAT Operator of the Year. And this year, the plant received a Platinum 11 Peak Performance Award from the National Association of Clean Water Agencies (Washington, D.C.) for its perfect compliance record.

 

Major Construction
The WEAT awards have extra significance because a major construction project during 2006 and part of 2007 put severe strain on plant operations. The project installed biological phosphorus removal (with chemical backup) to meet a newly required permit limit of 1 mg/L, biological odor control at the headworks, and a second belt filter press. During construction, the plant had to maintain continuous treatment, presenting a number of operational challenges.

 

Headworks Bypass
To coat the concrete walls of the influent channels and install the odor-control facilities, operators had to bypass the headworks until the work there was complete. The bypass system had to be installed during the middle of the night, when flows were at their lowest. Plant staff coordinated with all customer cities ahead of time — the Lakeview plant serves eight communities in Denton County — to ensure that all 15 lift stations that directly affect flows at the plant were pumped down the evening prior to the work. The pump stations were used for temporary storage in the system during the plant shutdown.

Plant operators were onsite continuously during the headworks bypass tie-in with a vacuum truck at the ready in case an upset occurred — either at the plant or at a customer city facility.

Adding to this challenge, the bypass system was supposed to be in place for only a few weeks. However, after the initial curing period for the coating, the material in several areas had to be removed and reapplied. As a result, the plant operated without screening and grit removal for more than 2 months. The grit and miscellaneous material that ended up in the treatment process created numerous operational and maintenance headaches for months afterward.

 

Juggling Aeration
Additionally, the improvements to provide biological phosphorus removal required that each of the plant’s two aeration basins be taken out of service, one at a time. The work removed air diffusers to create an anaerobic zone and installed baffle walls and mechanical mixers. Usually, the plant operates both basins in parallel.

To accommodate the construction, operators had to coordinate drawing down one basin and transferring all flows to the remaining basin in service. When the work in the first basin was complete, the mixed liquor inventory had to be transferred from the in-service basin to the empty basin, flows introduced, and the system stabilized before the second basin could be taken out of service for the work to be done there.

Throughout all of this, the Lakeview staff kept the plant operating smoothly and in compliance with all permit parameters.

Today, the advanced treatment process begins with fine screening, followed by grit removal and flow equalization. In the plant’s two aeration basins, activated sludge with biological phosphorus removal provides secondary treatment. Two circular clarifiers allow for final clarification. Final effluent polishing is provided by two traveling bridge filters and two banks of ultraviolet disinfection. Lakeview discharges its effluent directly to Lewisville Lake, a major source of drinking water for the cities of Dallas and for Upper Trinity. In fact, Upper Trinity has obtained a reuse permit from the State of Texas for much of the treated effluent that is discharged into the lake.

 

Good Neighbors
In addition to maintaining excellent treatment, the plant also is operated and maintained to be a “good neighbor.” As is increasingly the case for wastewater treatment plants everywhere, housing developments are filling what were once vacant areas surrounding the plant.

With that in mind, the Upper Trinity Regional Water District set in motion the upgrade to the existing odor-control system described above. Additionally, the Lakeview plant’s campus is carefully landscaped and maintained. In fact, the plant received the Yard of the Month award from the City of Lake Dallas for July 2006.

 

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