Hats Off to Hands-Off Flow Monitoring at Whitpain Township

With over 100 miles of sanitary sewer lines and five pump stations in their charge, Whitpain Township Sewer Department (Whitpain) personnel are always on the lookout for new tools, techniques and training that will allow them to more efficiently accomplish their long list of day-to-day tasks. Whitpain is a thriving Pennsylvania community recently rated by Philadelphia Magazine as one of the best places to live in the Philadelphia suburbs. From sewer line inspections to pump station maintenance and everything in between, Whitpain Sewer Department personnel know that efficiency is 'keyä. For them, the concept of working 'smarterä is nothing new, but instead a commitment they have embraced for many years.

A prime example of the townshipâs commitment lies in the accomplishments made in their wastewater flow monitoring program. In 2002, a decision was made by the townâs Engineering Department to connect Whitpainâs newly laid sewer lines to the interceptor lines of its neighboring town, Lower Gwynedd Township. Independent consulting engineering firms were contracted by each township to oversee the project. S&C Consulting would represent Whitpain while BCM Consulting was hired by Lower Gwynedd. Both firms concurred that the acquisition of accurate flow monitoring equipment would be a mandatory project requirement in order to successfully audit the flows. Although the meters were not being used for conventional billing purposes, an accurate account of each townshipâs flow was essential.

Low velocity conditions experienced in several of the applications would prove to be a challenge for existing flowmeters owned by Whitpain as well as the majority of new flowmeters currently available on the market. Gus Belmont, Sewer Department Superintendent, states, 'A lot of our sewer line flows, except our interceptors, do not have the amount of velocity needed to be seen by our existing flowmeters.ä Flowmeters with submerged style flow sensors were previously purchased by the township for their collection system monitoring applications. In the rugged sewer environment, submerged flow sensors used in combination with low velocity flows can increase the potential for sensor fouling by debris. Sensor fouling can result in increased maintenance as well as lost flow data. Albeit the flowmeters that were purchased by the township years earlier were at the time considered state-of-the-art for open channel flow monitoring, the use of the meters in the low flow applications had become problematic.

Prior to the current Whitpain/Gwynedd flow monitoring project, Whitpain had contracted the services of Savannah Environmental Inc. Consulting/Services Group (Savannah Environmental) to perform an Inflow and Infiltration (I&I) flow monitoring study to assess the adequacy of their existing collection system. The township was impressed with the performance of the flowmeters used by Savannah Environmental and inquired about directly purchasing the meters for their upcoming flow monitoring project. The meters used in the study were the Flo-Dar Radar Velocity/Area Open Channel Flowmeters, recently introduced by Marsh-McBirney.

The Flo-Dar meter is the worldâs first radar velocity flowmeter and utilizes a remote, 'above-the-flowä sensor to accurately monitor flows. Sewer Department personnel quickly realized the benefits they would derive from the use of Flo-Darâs non-contact sensor in their flow monitoring program. Flo-Dar combines digital doppler radar velocity sensing technology with ultrasonic pulse echo level sensing to remotely measure open channel flows under a wide range of flows and site conditions, including the low flows encountered at Whitpain. In addition, maintenance problems due to fouled sensors would be forever eliminated. Belmont states, 'We contacted Marsh-McBirney and found out we were able to trade in our old Flo-Toteâs toward the purchase of the new Flo-Dar meters.ä An order was placed for four (4) portable (Battery Powered) Flo-Dar meters. Belmont adds, 'We currently have 3 of the 4 meters installed. One meter is on an interceptor line by itself and one is installed after Lower Gwyneddâs meter. The third is on a 24" line and monitors the two meters coming in behind it.ä When asked which single meter feature he felt was most beneficial, Belmont replies, 'The fact that you donât have to touch anything down there is 'perfectä. I have been doing this for 18 years so Iâve seen it all.ä It is easily understood why anyone working in the sewer environment would prefer the 'hands-offä approach and freedom from entering monitoring sites that the Flo-Dar meter affords. He further adds, 'These meters are nice. I also like the battery system. With the sampling rate I use I can get a month out of the two batteries, where I only got a week with the old Flo-Totes.ä The increased battery life of the Flo-Dar meters allows Belmont to only visit the sites on a monthly basis to download the flow data, an important time and money savings for the township. Belmont comments, 'After we purchased the meters, Savannah Environmental came out and gave us software training. They are very good instructors and we learned a lot. I just purchased a Pocket PC to use with the Flo-Ware software to read the meters. We have a laptop but it just becomes a little bit easier with the Pocket PC out in the field. I have already budgeted for additional Pocket PC's because it really makes the field work so much faster.ä A monthly summary sheet is easily printed from the Flo-Ware software program and provided to the consultant. Belmont then works with the raw flow data for their departments own in-house needs.

As time and wintry weather conditions permit, the fourth Flo-Dar meter will be installed in a new monitoring site within the townâs collection system. With more than two years of successful Flo-Dar flow monitoring under his belt, Belmont looks forward to continued meter success. If is certainly clear that the use of the Flo-Dar meters has allowed Belmont and other sewer department personnel to work 'smarterä. In fact, they are already envisioning additional applications for the meter as their township continues to grow!