Tuesday, September 10, 2024
10:30 AM - 11:00 AM
Location Name
MLGW's New Allen Pump Station - A New Water Treatment Facility Combined with Existing Infrastructure
Rehabilitation - DW

Background: After significant deficiencies were identified at the Allen Pump Station (PS) during a plant condition assessment, Memphis Light, Gas, and Water (MLGW) retained HDR under a separate contract to identify feasible, long-term strategies to upgrade the performance and reliability of the PS. It was originally constructed in 1951 and has a capacity of 30 MGD. Some deficiencies included a failing roof, non-compliant troughs with TDEC requirements, shallow filter structure, poor water circulation, age and operability of high service pumps, and a nonreliable back-up power supply. Approach: Based on the review of the available documents from the original design as well as the on-site condition assessment, HDR recommended that rehabilitation work was insufficient, and a new Allen PS should be constructed. This recommendation includes a new seismically designed structures for filtration and pumping, and does not include a new aerator structure, solids handling basins, or finished water reservoirs. Rather, improvements to each structure would be included in design to extend service life and improve performance. A key benefit of this alternative is that it will minimize plant shutdowns with no production outage expecting to last more than one week, but also provides a challenge in siting new buildings on-site where the existing ones need to remain until project completion. Findings: An innovative finding during design concluded that separating the filtration and pumping functions as part of the new facility could provide both cost and performance benefits. A unique process challenge was being limited hydraulically by the structures being used as part of the new plant as well, the aerator and finished water reservoirs. This provided two hydraulic elevations that were firmly set and could not be changed. Allen PS is also one of two treatment facilities that supplies Memphis’ industrial sector. With the arrival of Ford’s Blue Oval to the area, many additional industries are seeking to relocate to the area. Allen PS’s new pump facility will be equipped with a higher pumping capacity to help accommodate these loads, with the possibility of future expansion. Conclusion: After identified improvements are made, it is anticipated that the Allen PS would have been comprehensively overhauled through the construction of new filtration and high service pumping facilities together with rehabilitation of aeration, reservoirs, and solids handling. The equipment and monitoring instruments would be completely modernized with performance meeting or exceeding regulatory standards. The building structures would be upgraded to mitigate seismic events, be generally code-compliant, and weatherproof. After the designs are finalized (expected in Q1 of 2025), full scope of services will include project management administration, site services, basis of design report, engineering investigations, plans and specifications development, permitting, cost estimating, and QA/QC reviews. Because the extent of defects at the PS were unexpected, MLGW trusted the HDR team to act swiftly providing a cost-effective and reliable design that will ensure quality service to their customers for years to come.