Shrewsbury Finds I&I Source – Decreased Cost Dramatically and Provided a Framework for Future Development

The borough of Shrewsbury in York CountyPennsylvania has been experiencing a lot of growth in recent years.  With growth came the need for more industrial and commercial company connections to their North and South interceptor wastewater lines which feed into the Deer Creek Pump station. The added industry and potential I&I put a strain on the existing infrastructure and engineers needed to know if an upgrade was needed.

The Shrewsbury Authority needed to determine if the inceptor lines had additional capacity to handle the current and expected increased demand. To do so, they used FloWav, Inc. meters to conduct a study to determine the flow conditions and determine their capacity and detect potential I/I.

FloWav suggested two different sensors coupled with its FW-33 loggers and web module to monitor and record the data collected.  The first sensor, Pipeline Model PSA-AV , an open-channel, area velocity sensor combines pressure depth and continuous wave Doppler technologies. The authority also integrated FloWav’s dual crystal, open-channel StingRay Ultrasonic Sensor – specifically designed for accuracy in depth data in rugged environments.

With both lines metered by FloWav technology the Authority was able to determine the South interceptor (8-inch diameter), had additional capacity available, however, the North interceptor (12-inch diameter) was full. With this information now known Shrewsbury set out to determine the cause of the problem and how to decrease the wastewater flowing through the North interceptor.   

Through detailed analyses both meters were moved to the North interceptor, monitoring an upstream manhole close to the pump station to determine the source of I/I. When it rained, and the ground water tables increased, FloWav technology being utilized was able to pinpoint the location and quantity of leaks in the pipe. 17K gallons of rainwater and ground water per day was discovered to be leaking onto the North interceptor.

The FloWav meters will remain through early winter to continue collecting data to provide the quality and quantity of data needed to determine the best solution for repairing the interceptor. Not only will Shrewsbury save hundreds of dollars daily on sewage treatment, but the data will also provide developers with the information they need to plan and budget for additional or rehabilitation of the existing sewer lines. Additionally, Shrewsbury will now know if the installation of larger lines is needed to keep up with growth demands.