Overview
Aqua Pennsylvania Wastewater’s (Aqua’s) Lemon Street Pump Station was undersized to accommodate collection system flows, resulting in several upstream sanitary sewer overflows per year. The primary cause of the increased flows is inflow and infiltration (I&I), but despite Aqua’s years of effort to curtail the I&I, they decided to upgrade the capacities of the pump station and downstream force main and gravity sewers, if necessary. We helped Aqua select the necessary upgrades and perform subsequent design to upgrade the wastewater collection system components.
Solution Details |
The Lemon Street Pump Station was constructed in the early 1970’s, and featured a duplex wet well/dry well configuration, and a design pumping capacity of 800 gpm. After performing a detailed review of the capacity of the existing pumps, force main and downstream gravity sewers and flow data. It was determined that the capacity of the pump station could be increased by replacing the two existing dry pit pumps with three submersible pumps located in the existing dry well. This increased the capacity of the pumps and the volume of the wet well, thus mitigating concerns of frequent pump cycling. By selecting pumps with higher discharge heads, the force main would not need to be upsized. Additionally, it was determined that the gravity sewers downstream of the force main were also adequate for the higher pumped flow rate. Normally, the Pennsylvania Department of Environmental Protection (PADEP) will require an amendment to the Municipal Act 537 Plan if a pump station capacity is being increased, which can be an expensive and time consuming process. We successfully convinced the PADEP that by increasing the number of pumps in the pump station with similarly sized pumps as the existing, Aqua improved the mechanical reliability of the pump station and not necessarily the rated capacity of the pump station. This approach obviated the need for Act 537 Planning, saving time and money. | deliverables - 3 new submersible pumps
- Addition of a comminutor ahead of the pumps
- Variable frequency drives for the pump motors
- Upgrades to the local RTU
- Addition of an odor control unit
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