Indirect Potable Reuse Evaluation, Permitting Support, and Design for Hamby Wastewater Treatment Plant, City of Abilene, Texas

Plummer and our partner in Abilene, eHT, have been working with the City since 2008 to augment Lake Fort Phantom Hill (LFPH), one of the City’s potable water supplies, with reclaimed water. Project planning began with an evaluation of LFPH to determine appropriate water quality targets and treatment requirements for a discharge to the lake. The evaluation included assessment of reclaimed water blending ratios and detention times, development of water quality goals for disinfection and chemical constituent removals, treatment recommendations as well as evaluation of compliance with the Texas Surface Water Quality Standards for dissolved oxygen, nutrients, TDS, chlorides, and sulfates.

Plummer and eHT subsequently assisted the City with plant design upgrades to accommodate the discharge of reclaimed water to the lake. The treatment plant upgrades were designed to allow the City to discharge up to 7 MGD of advanced treated effluent to the lake. At this rate of augmentation, a significant portion (> 50 percent) of the lake may be comprised of reclaimed water during low rainfall periods. The advanced treatment processes (membrane bioreactors, ozonation, biological activated carbon) were selected to provide additional treatment for removal of pathogens, and trace organic constituents in the reclaimed water. In addition, a parallel reverse osmosis treatment process is included to control dissolved solids concentrations. Plummer and eHT are also working together to amend the TPDES permit to add an outfall to LFPH. Because it is on the critical path, the permitting project requires working closely with the TCEQ to ensure that the permitting process will proceed smoothly.