For the past 23 years, Plummer has assisted the Town of Flower Mound with wastewater treatment plant engineering including: an expansion of the treatment plant from 2.0 mgd to 5.0 mgd in 1993; an odor control project in 1997; an effluent filtration and lime stabilization project in 1999; a wastewater collection and treatment system Master Plan in 2000; an expansion of the treatment plant from 5.0 mgd to 10.0 mgd in 2001; three rehab projects in 2010 to 2012; and, a solids facility plan in 2014 to refurbish existing facilities and address treatment options for when the local landfill closes. Currently, Plummer is working on the design and construction of solids facility improvements and an assessment of the plant’s capacity relative to increased peak flows.
Some highlights of these projects include:
- In the first expansion to the plant in 1993, the existing secondary system was converted from a combined trickling filter / aeration basin process to a nitrification process by removing the trickling filters and adding nitrification basins to provide adequate detention time. The project also included the replacement of the chlorine contact basins with UV disinfection.
- As part of the effluent filtration project in 1997, Plummer designed the first municipal cloth-media filter project in the state of Texas.
- In the second expansion in 2001, Plummer designed a new preliminary treatment structure with screenings and grit removal and a second treatment train with three sequencing batch reactors. The new preliminary treatment structure included two vortex-type grit removal units, two flooded-suction recessed impeller grit pumps and one vortex-type grit separator and conveyor belt grit dewatering unit. Low-head multi-tray grit removal units were new to the market at that time, so the decision was made to install the vortex-type grit unit. However, the concrete basin was designed to allow conversion from the vortex-type system to a low-head multi-tray without significant reconstruction.
- A solids facility plan was developed for near- and long-term improvements to the solids handling facilities and identified the most cost-effective process for meeting Class A biosolids standards in the event that the nearby landfill closes, eliminating the landfill disposal option.
- As part of the solids facility plan, Plummer evaluated options for incorporating phosphorus removal into the treatment process in anticipation of future effluent limits. The goal included utilization of as much off the existing infrastructure as possible.
- Recent high rainfall events raised capacity questions. Plummer is currently evaluating the peak flow capacity of the plant and identifying options for managing peak flows.