Rittenhouse Force Main Study and Upgrade

Rittenhouse Pump Station Force Main Analysis

This report has been prepared by Gilmore & Associates, Inc. (G&A), at the request of West Norriton Township, to review and analyze the existing operating conditions of the Rittenhouse Boulevard Pump Station and 18-inch cast iron (C.I.) force main, as well as evaluate several cost-effective alternatives for increasing the pump station’s current capacity to meet the facility’s projected 20-year peak flow. This report is also a follow-up to the Rettew Associates, Inc. (Rettew) settlement and field inspection, which was conducted in February of 2016. The field inspection concluded the flow capacity of the station, with two pumps operating, was approximately 3,200 gallons per minute (gpm) or 4.6 million gallons per day (MGD), which is less than half of the projected flow capacity of 6,600 gpm or 9.5 MGD as documented in the Rettew Design Engineer’s Report dated August 2013. Additionally, the station’s current flow capacity of 4.6 MGD is approximately 2.2 MGD lower than the previous flow capacity prior to the 2015 upgrade (6.8 MGD), as well as 4.14 MGD lower than the Pennsylvania Department of Environmental Protection (PA DEP) permitted capacity of 8.74 MGD.

The projected 20-year peak flow for the Rittenhouse Boulevard Pump Station was determined based on a review and analysis of the recorded historical flows at the station and the anticipated future developments and connections, including projections in the Township’s Chapter 94 reporting and beyond (see Table 1). According to the recorded historical flows at the station, the average daily flow from January 2016 to September 2020, was approximately 2,106,900 gallons per day (gpd) and had an average daily dry weather peaking factor of 3.0. Additionally, according to the anticipated future developments/connections, it is projected that 960 new estimated dwelling units (EDUs) will be connected to the station within 20 years. Based on a standard 285 gpd/EDU, the projected 20-year flow addition to the station is 273,600 gpd. Summing the recorded historical average daily flow of 2,106,900 gpd with the projected 20-year flow addition of 273,600 gpd, the resulting flow is 2,380,500 gpd, which equates to a peak flow of 7,141,500 gpd (7.14 MGD) after multiplying by the average peaking factor of 3.0. Therefore, the projected 20-year peak flow and anticipated flow capacity need for the Rittenhouse Boulevard Pump Station is approximately 7.14 MGD or 4,960 gpm.

Rittenhouse Pump Station Force Main Analysis

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