Erie County’s investments in clean water are drawing accolades with the announcement of the Southtowns Advanced Wastewater Treatment Facility’s (AWTF) Influent Screw Pump Replacement Project as the Western New York Branch – American Public Works Association’s 2023 Project of the Year – Environment. This challenging $3.3 million project replaced the three influent pumps at the treatment plant, which were in constant service over the last 40 years, with new pumps. The original pumps were installed in the late 1970s when the treatment plant was built and went online in late 1980. These pumps were installed before the building shell around them was even completed and no provisions were made at the time of construction to replace the pumps, which made this project challenging.   

“My administration has made protecting and preserving our clean water resources a priority and this project furthers that goal, replacing components that have been in constant service for more than forty years and upgrading the wastewater facility in the process. This project was intricate and challenging due to its massive size and the requirements of the physical plant housing the screws, so planning, communication and teamwork were essential to its successful completion,” said Erie County Executive Mark C. Poloncarz.  “I thank our engineers, plant operators, maintenance staff, and other professionals in the Division of Sewerage Management for their work on this project. This investment improves service, protects our irreplaceable water assets, and will serve residents for years to come.”

Issues became immediately apparent following a 2021 study performed to determine the most economical method to replace the three influent pumps.  The original overhead gantry crane in this area of the facility, which was sufficient for maintenance purposes, was rated for 4 tons while each new screw pump weighs roughly 9 tons, excluding the weight of the motors and bearings. After evaluating options ranging from constructing large removable hatches in the roof to installing a temporary rigging/gantry system, the selected alternative was to upgrade the existing crane to a dual 6-ton crane system to be operated individually or synchronized. This alternative facilitated the pump replacement and can also be utilized for future projects.  Due to the tight footprint and existing layout of the facilities, replacement-in-kind of the screw pumps was selected.

The project required each of the large screws (approximately 42’ long by 8.5’ in diameter) to be lifted in one piece into an area of the treatment plant that must operate continuously to allow for wastewater treatment to be maintained.  The area where most of the construction was completed was classified as an explosion-proof environment, meaning that flame cutting to break up and remove portions of the existing pumps was not allowed. 

In addition, the new screws had to be installed in one piece as they are manufactured to a high tolerance to maintain balance during operation.  The dual crane system installed at the initial portion of this project allowed removal and installation of the various pump components (screw, motor, and bearings) while complying with work area requirements. 

After demolition of the first pump, it was determined that the grout bed was constructed differently than indicated on the record drawings, requiring modification of the grout placement and additional steel bar reinforcing.  The previous installation methods included using the pump itself to form the grout surface by operating the pump during the grout installation. The new pump manufacturer, to not risk damage to the new screws, provided a steel form that would shape the surface of the grout.  This required the screws to be set multiple times during the construction process to achieve correct alignment of the forms and screws.

The pumps were manufactured in Europe and had to be shipped via freighter. The manufacturing and shipment time delayed the actual on-site construction work until 2023 – approximately one year later than anticipated.  The total investment for this project was $3,362,500. Working with the Division of Sewerage Management on the project were:

• Design Team: DiDonato Associates Engineering and Architecture, PC – Project Management, Structural Design; JM Davidson Engineering, DPC – Wastewater Engineering; Trophy Point, LLC – Cost Estimating.
• Contractors: Hohl Industrial Services, Inc. – General Contractor; CIR Electrical Construction Corporation – Electrical Contractor.

For more information:

On the Erie County Division of Sewerage Management, visit https://www3.erie.gov/dsm/   

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