Huntsville Water Treatment Plant Expansion, Trinity River Authority of Texas

APAI conducted the first Comprehensive Performance Evaluations (CPE) performed in Texas outside of the Texas Commission on Environmental Quality (TCEQ) or Environmental Protection Agency (EPA) for the Trinity River Authority’s Huntsville Water Treatment Plant. APAI personnel have been trained by the TCEQ to perform CPEs and Comprehensive Technical Assistance (CTA) for water treatment plants. The TCEQ requested that APAI assist in training CPE and CTA teams for the TCEQ.

APAI also conducted a low-pressure membrane pilot study with four low-pressure membrane equipment suppliers. The two pressurized and two submerged membrane systems successfully completed the ultrafiltration / microfiltration 90-day pilot study.

APAI also completed two consecutive improvements projects, and a preliminary design for a 4 MGD expansion to the Trinity River Authority’s Huntsville Water Treatment Plant. APAI designed improvements to the plant’s clarification system, including replacement of two upflow units with two hydraulically mixed solids contact / tube settler units, and construction of a third solids contact / tube settler clarifier, and rehabilitated the existing four filters with new media, a suspended air scour backwash system, new filter control valves, and a new plant SCADA system. Butterfly valves with quarter-turn pneumatic actuators were utilized for the filter control valves. Special construction sequencing instructions were included in the contract bid documents to ensure that the plant was fully operable during the renovations to the clarifiers and filters.

In a subsequent project, APAI designed a new 30 MGD raw water intake/pump station in the Trinity River immediately upstream of Lake Livingston, new chlorine dioxide disinfection system, two new solids contact / tube settler clarifiers, new chemical feed system, a new concrete lined sludge holding basin, a settled water storage tank, and an 8 MGD cooling water pump station to provide cooling water for a new power plant. The plant receives raw water with turbidities ranging up to 1,000 NTU and greater from the Trinity River and consistently produces settled water below 0.5 NTU and finished water below a 0.1 NTU.

The Trinity River Authority (TRA) retained APAI to design the expansion of its 8 MGD Huntsville Water Treatment Plant (WTP) to 12 MGD. The design consists of four new filters using an innovative technology for biological nitrate removal; one new baffled, concrete clearwell; installation of baffles for the existing clearwell; four new energy-efficient high service pumps mounted on the new clearwell; new backwash pump station with two new backwash pumps; a new lime feed, and biological denitrification chemical feed units. A new electrical feed system and backup generator were also included.

APAI also performed a surge analysis for the raw water pipeline, as well as a water system security and risk management plan. A surge tank and replacement of 3,000 feet of raw water pipeline were designed for the raw water delivery system.