The wastewater treatment plant (WWTP) which served the City of Glen Rose was originally constructed in the 1950’s. The City’s WWTP was expanded from 0.25 MGD to 0.6 MGD in 1990, in response to noncompliance with permit limits. Having exceeded the service life for the treatment units, eHT designed a new 1.0 MGD treatment facility.

While there were significant site constraints at the City’s existing facility, a cost comparison was developed to evaluate relocating the WWTP off-site as opposed to working within the given site constraints. It was determined that the cost to reconstruct the entire facility would be approximately double the cost of working with the existing site, so planning and design efforts proceeded with upgrading the existing facility. The new WWTP facility was funded under the Texas Water Development Board’s (TWDB) Economically Disadvantaged Program (EDAP) program, which requires the completion of a facility engineering plan to complete the planning process and is a more significant effort than what is required for typical TWDB-Clean Water State Revolving Fund (CWSRF) projects.

Because of the City’s requirements for Type I reuse capability, improved system redundancy, implementation of an automated SCADA system, and the flexibility to meet nutrient limits in the future, the City and eHT focused on process alternatives incorporating either CAS, MLE, BNR, SBR, or MBR technologies in order to meet the City’s project goals. After completing a detailed evaluation of each process option, an SBR system was selected by the City, supported via the use of an MLE process for energy recovery and tertiary filtration using cloth disc filters to meet Type I reuse goals. The treatment system was selected on the basis of required construction footprint, capital and operational cost and operational flexibility and reliability while meeting 10 mg/L BOD, 15 mg/L TSS and 3 mg/L ammonia permitted effluent limits, as well as providing the capability to meet Type I reuse requirements.

The City’s new WWTP includes a mechanical bar screen, grit removal system, an influent wastewater pump station, a secondary MLE-SBR process designed for enhanced energy recovery, tertiary filtration using cloth disc filters, chlorine disinfection, aerobic solids storage and mechanical solids dewatering. Also included in the scope of the project is the preparation of a new TPDES discharge permit, a 210 Type I reuse authorization and a comprehensive Operations and Maintenance Manual.