Flow Metering System Limits Need for Confined Space Entry

Due to population increases in recent years, the 100-year-old sewer system in the City of Hagerstown, MD, and its treatment plants were quickly becoming overwhelmed. Inflow and infiltration work was ordered in an effort to eliminate documented overflow violations.

“The I&I work we are doing is focused on the old section of the inner-city,” said Bijan Haghtalab, Project Coordinator with the City of Hagerstown Water and Sewer Department. “Some minor I&I work is also taking place in the new growth area.”

Early on, city planners and developers included the desire to use only high-end technology for new equipment purchases. This decision significantly narrowed the flowmeter selection process.

“The city is taking a high-end technology plan for everything that we do. Even though it’s a small city in comparison, we have access to good technology and IT here,” Haghtalab said. “We figured that Marsh-McBirney flowmeters would best fit our goals plus Marsh-McBirney’s reputation is so good in the industry.”

The company’s Flo-Dar family of products combines digital doppler radar velocity sensing technology with ultrasonic pulse echo level sensing to remotely measure open channel flows. Use of the meter eliminates the need for maintenance caused by fouled sensors and the meter can be re-installed and removed from street level without the need for confined space entry.

Models are available for both portable (battery powered Flo-Logger) and permanent (120/240 vAC or 12 vDC powered Flo-Station). Optional features for deep channels (extended range depth), surcharge conditions, or remote communication capabilities are also available.

A number of the meters used by Hagerstown also include one of Marsh-McBirney’s newest features, Mobile RF. The radio-based system reduces routine data collection costs with the use of a “drive-up” data collection feature. With Mobile RF there is no need to remove the manhole cover for operation and data can be uploaded up to 100 feet from the monitoring site. By eliminating confined space entry, traffic control and adverse weather concerns during data downloads, customers can save thousands of dollars annually at each flow monitoring site.

An order was placed for 10 Flo-Dar meters that would be used in pipe sizes ranging from 20-36 inches in diameter.

“We try to keep people out of the sewer as much as possible and to cut down on maintenance and the Flo-Dar does that for us,” Haghtalab said. “The meters are definitely a big help in mains 36 inches and up. It puts people in danger every time you do some maintenance so measuring the flow without actually having to be in the manhole is a blessing in disguise.”

After installation of the meters was complete, a decision was made to broaden the initial I&I study. Since funds were not budgeted for additional meters, the city chose to use a rent-to-own option offered by Marsh-McBirney.

The company offers a Rental Program for its two most popular open channel flowmeters, the Flo-Dar Radar Velocity/Area Flowmeter and the Flo-Mate Velocity Flowmeter. Its Rental Services Division is responsible for meter rental and technical support.

The City of Hagerstown chose the company’s Rent-to-Own option so the study could move forward in a timely manner without the need to immediately purchase additional meters.

There are currently two options available in the Rent-to-Own program. Option one allows the customer to purchase the unit they are currently renting. Marsh-McBirney will apply 70% of the total paid rental fees toward the current list price of the unit. The flowmeter is purchased in an “as-is, where-is” condition. This means that at the time of sale of the rental unit, the unit is sold in its current operating condition and any existing time that remains on the standard warranty (based on the original manufacture date) will also be included.

Its second Rent-to-Buy option is for rental customers that want to purchase a new flowmeter. If the customer chooses this option, Marsh-McBirney will apply 35% of the total paid rental fees toward the current list price of a new unit. A full standard warranty is included with this option.

“Since it wasn’t in our budget to buy additional meters at that time we need them we rented 10 Flo-Dar meters with an option to purchase them at the end of the contract,” Haghtalab said. “At the end of the rental period in August 2005 I notified the city that the study was going to take an additional four to five years to complete. I felt it was most beneficial for the city to purchase the meters and that’s what we did.”