Regional Treatment Plant Hydraulic Improvements

Grand Prairie, Texas

Perkins Engineering Consultants, Inc., serving as a subconsultant to another firm, was responsible for identifying hydraulic relief improvements needed to enable this 152-mgd regional plant to better distribute flows from its 12 secondary clarifiers to its 32 low-head effluent filters, some of which are being abandoned while others are receiving significant capacity upgrades via cloth media retrofits. Two relief tunnels were identified and designed. The first involved a relatively short but complex 84-inch relief tunnel to connect the effluent troughs from two isolated banks of clarifiers. This pipeline was partially installed by open cut, but due to electrical duct banks and other large utilities in the vicinity, specific portions had to be installed by tunneling in tight, confined operating plant areas and beneath roadways. This project was completed in 2016. A second cast-in-place relief tunnel is scheduled for construction in 2017.

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Plant Rehabilitation

Sachse, Texas

The North Texas Municipal Water District recently contracted with PECI to design miscellaneous improvements to the Muddy Creek Wastewater Treatment Plant in Sachse, Texas. PECI specified a biological odor control system (bioscrubber) with organic media for the influent lift station. This allowed the District to reduce the usage of the existing chemical scrubber located at the solids handling building and resulted in substantial chemical and energy costs. To reduce corrosion in the existing electrical room, PECI specified a positive pressurization unit to pressurize the room with scrubbed air. In addition PECI redesigned the existing chemical storage area with three new bulk tanks to store a full truckload of sodium hydroxide and sodium hypochlorite. The project was completed in 2011 at a cost of $579,000.

Primary and Secondary Clarifier Rehabilitation

Lucas, Texas

Perkins Engineering consultants is assisted the North Texas Municipal Water District with rehabilitation of four large primary clarifiers and four secondary clarifiers at the District’s Wilson Creek Regional Wastewater Treatment Facility. The project involved assessment and repair of corrosion damage to concrete structures, rehabilitation of four 135-foot aluminum low-profile basin covers, weir and baffle replacements and skimming system rehabilitation. An assessment of the effectiveness of the scrubbing and ventilation systems serving the primary clarifier was also included.

Blower and Aeration System Upgrade

Garland, Texas

Perkins Engineering Consultants, Inc. served as prime design consultant assisting the City of Garland with an update of the activated sludge process in the 24 MGD Rowlett Creek Wastewater Treatment Plant. The project included installation of new high speed turbo aeration blowers, air piping, and fine bubble membrane diffusers. A grit and snail removal basin and equipment were also included in this project for continuous removal of snails from the plant’s trickling filter process. The existing aeration system included four multistage centrifugal blowers. The project was placed in service in 2011 at a cost of $2.6 million.

Screen and Conveyor System Replacement

Garland, Texas

Perkins Engineering Consultants, Inc. assisted the City of Garland with replacement of screening and conveyor equipment in the headworks building at the City’s 24-MGD Rowlett Creek Wastewater Treatment Plant. Equipment installation was performed by City personnel and was placed in service in the Spring of 2008.

Plant-Wide Rehabilitation Improvements

North Texas Municipal Water District

Perkins Engineering Consultants, Inc. was retained by the North Texas Municipal Water District to assess and prioritize rehabilitation needs throughout the District’s 24 MDG Rowlett Creek wastewater treatment plant. The treatment facilities had been constructed and expanded under numerous contracts, with many facilities over 40 years of age. Corrosion and structural deterioration was a concern in a number of areas.

Perkins Engineering Consultants, Inc. served as prime consultant responsible for detailed design of the highest priority improvements. This project included extensive corrosion repairs to a number of covered concrete structures within the plant, drainage improvements inside the plant’s dewatering building, addition of a 5000 CFM bioscrubber for odor control, replacement of the plant’s aging return and waste activated sludge piping and distribution system, rehabilitation of approximately 3500 square yards of in-plant paving surfaces, and addition of access and security improvements. Construction was successfully completed in 2010 at a cost of $1.6 million.

Plant Rehabilitation Needs Assessment

Trinity River Authority of Texas

Perkins Engineering Consultants Inc. served as prime consultant responsible for a plant-wide assessment and prioritization of rehabilitation needs for this 159 MGD regional wastewater treatment facility. The effort included review of the age, criticality, and condition of dozens of major process units, along with development of projected costs for rehabilitation. Coordination with multiple consultant teams was required. The evaluation identified recommended in-plant rehabilitation totaling approximately sixty million over a span of six to ten years.

Regional Treatment Plant Clarifier and Thickener Rehabilitation

Grand Prairie, Texas

Perkins Engineering Consultants, Inc. served as the mechanical and process engineer for rehabilitation and improvements to the CRWS plant. This is a multifaceted project involving a large design team, in which PECI led design efforts for:

  • New primary clarifier scum facility;
  • Mechanism replacement on large rectangular clarifiers;
  • Mechanism replacement on circular gravity thickeners:
  • Aluminum truss supported flat covers on the gravity thickeners; and
  • Corrosion and coatings repairs on multiple structures.

The overall project bid at $23 million and is currently under construction.