Formed as a "special purpose" district in 1958, the Hazel Dell Sewer District provides wastewater services for approximately 76,000 residents that reside just outside the city limits of Vancouver, Wash.
Created by a group of visionary businessmen who realized that area septic systems would be inadequate to serve the growing population, today the district performs administrative, finance, maintenance and engineering services for their 36 square mile service area.
The district's Maintenance Department is responsible for maintenance and management of their service area and facilities including 356 miles of sewer line, 51 pump stations, 650 satellite septic tank effluent pump (STEP) systems as well as passenger vehicle and equipment fleets.
Additionally, the district serves as a problem-solving advisor to its customers and other governmental agencies. The district has not operated a wastewater treatment facility since 1975 but instead has contracted with Clark County Public Works and the city of Vancouver for wastewater treatment.
Keeping up with growth
Rapid growth has occurred since 1990, with the first quarter of 2005 including the addition of 65 new subdivisions, 22 new commercial projects and an average of six homes connecting to the district's sewer system daily.
Ron Miller, electrician for the Hazel Dell Maintenance Department said, "the district handles everything outside the city (Vancouver) limits but inside the urban growth boundary. We were in the market for replacement flowmeters for our old meters that we had on a turn-key contract arrangement."
The flowmeter manufacturer for the meters being replaced had been contracted to install and maintain the flowmeters as well as provide the collected flow data from each of the monitoring sites.
He added, "the turn-key approach was very expensive and the proprietary software costs were high. For the amount of money we had spent for that flow data we could have purchased ten (10) Marsh-McBirney Flo-Dar meters."
Regarding the accuracy of the flow data received from the turn-key project, Miller added, "I don't believe that those sensors on bands in the pipe on those meters are terribly accurate anyway and they definitely had their maintenance and fouling issues."
After an introduction to the Marsh-McBirney Flo-Dar Non-Contact Velocity/Area Meter by local representative Bainbridge Associates, the district placed an order for five Flo-Dar's for portable monitoring and for a permanent monitoring application.
In the flow
The Flo-Dar Open Channel Flowmeters provide an ‘out of flow' approach to sewer and other open channel flow monitoring applications. Combining digital doppler radar velocity sensing with ultrasonic pulse echo level sensing Flo-Dar provides open channel flow monitoring without the fouling problems associated with submerged sensors.
Portable flow monitoring tasks within the district included Inflow & Infiltration (I&I) monitoring for analyzing maintenance and capacity issues. An order was also placed for 18 permanent Flo-Dar sensor mounts. Mounts for both portable (jack-bar tension type device) and permanent (hardware affixed permanently) applications are available but are not inexpensive.
The district has installed the meters in key monitoring locations allowing them to easily move a sensor from one site to another without the use of confined space entry.
Miller added, "we had the old meters on CDPD or phone lines and that was expensive installation and ongoing operating costs. We did not move the meters around like we wished we could have. What we're doing now with the use of the Flo-Dar's allows us to easily move the meters and have much more control. With the Flo-Dar we do our own installs."
A unique application was in store for the one permanent Flo-Dar meter purchased by the district. The meter would be installed in a restricted accessibility location within the district's territory. Installed on one of the district's main trunk lines, this 24-in., line, even though not large, is a big line for the location that it serves.
Miller added, "we mounted a control panel out there at the site and set up solar panels so everything was independent of any power source. We use our SCADA radio and PLC to bring the data back here to our SCADA system. For just the price of the hardware and the ease of access to the sensor it quickly paid for itself."
In any location it is typically a two-man confined space operation. With the use of Flo-Dar it's now become a "one-man show." Every additional access required to enter the manhole adds increased monitoring costs but Flo-Dar can actually save you thousands of dollars at each monitoring site annually by reducing maintenance typically caused by fouled submerged style sensors as well as confined space entry equipment and labor costs.
"Last week I went out to the site and installed the Flo-Dar myself," added Miller. "It is our practice to have a crew go around the set the sensor brackets up, collect offset information and pipe diameters for later sensor installation without manhole entry.
We examine level, flow and velocity data and provide reports from the collected flow data."
Through the use of software manufactured by The National Institute, known as Lookout, the flowmeter data is transferred back to our central computer. Personnel have the flexibility to either chart the recorded flow data through Lookout or via Marsh-McBirney's Flo-Ware, flowmeter management software. Regarding the use of Flo-Ware, Miller added, "I'm not a computer expert by any means but with the Flo-Ware software I myself find it pretty easy to use. When we get the data we can provide many types of requested reports. For example, if our Engineering Group asks for some flow data graphs to know what's going on, such as peak flows on weekends and how it affects the up and down with the I&I, or any heavy rainfall events and its affect all can be very easily shown."
The remote Flo-Dar permanent monitoring site provided the experience that will serve as a pilot program for more solar sites in the future. Miller stated, "it has been nice having that site where we have Flo-Dar permanently set up. We can now take that experience and knowledge and run with it."
The Hazel Dell Sewer District is currently involved in a long-range I&I planning effort. Miller added, "data from the Flo-Dar meters will provide critical information that will go into that effort."
As the district continues to see rapid growth, they can count on their investment in the flow instrumentation from Marsh-McBirney to provide accurate flow data that in the end could provide savings for their entire flow monitoring program.
About the Author:
Marcia Kinley is the Marketing Services Manager for Marsh-McBirney, Inc. and can be reached at firstname.lastname@example.org or by phhone at 800-368-2723.