Formed as a 'special purposeä 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 or, Washington. 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 vast service area.

The Districtâs Maintenance Department is wholly responsible for maintenance and management of their service area and facilities including 356 miles of sewer line, 51 pump stations, 650 satellite septic 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 Clark County Public Works and the City of Vancouver for their wastewater treatment. Rapid growth in the first quarter of 2005 indicates the addition of 65 new subdivisions, 22 new commercial projects and an average of 6 homes connecting to the Districtâs sewer system daily.

Ron Miller, Electrician for the Hazel Dell Maintenance Department, comments, 'The District handles everything outside the city limits but everything 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.ä 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 adds, 'The turn-key approach was very expensive, in fact it was horrendous. For the amount of money we had spent for that flow data we could have purchased ten Marsh-McBirney Flo-Dar flowmeters.ä Regarding the accuracy of the flow data received from the turn-key project, Miller adds, 'I donât 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.ä

After an introduction to the Marsh-McBirney Flo-Dar Non-Contact Velocity/Area Meter by local representative Ken Navidi of Bainbridge Associates, the District placed an order for five (5) Flo-Darâs; (4) for portable monitoring and (1) for a permanent monitoring application.

The Flo-Dar Sewer and Open Channel Flowmeter provides a revolutionary 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 accurate open channel flow monitoring without the fouling problems associated with submerged sensors. Portable flow monitoring tasks within the District included Infiltration & Inflow (I&I) work relating to 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. 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 adds, 'We had the old meters on CDPD or phone lines and that was expensive with the manufacturerâs license. We did not move the meters around like we wished we could have. We paid a lot of money for the other meters compared to what we were getting back. What weâre doing now with the use of the Flo-Darâs allows us to easily move the meters and have much more control. With the Flo-Dar we do our own installs.ä

A unique application was in store for the one permanent Flo-Dar meter purchased by the District. The meter would be installed in a remote canyon location within the Districtâs territory. Installed on one of the Districtâs main trunk lines, this 24ä line, even though not large, is a big line for the remote location that it serves. Miller adds, '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.ä For the cost of the installation bracket alone for the Flo-Dar, Miller states, 'For just the price of the hardware and the ease of access to the sensor that it provides quickly pays for itself. In our remote locations such as this canyon location it is typically a two-man confined space operation. With the use of Flo-Dar itâs now become a 'one-man show.ä Every additional entry 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.

Solar power and "zero maintenance" made Flo-Dar the right choice
for metering a remote canyon location.

'Last week I went out to the canyon site and installed the Flo-Dar myself,ä adds 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.ä

We examine level, flow and velocity data and provide reports from the collected flow data.ä Through the use of software manufactured by National Instruments, 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-McBirneyâs Flo-Ware, flowmeter management software. Regarding the use of Flo-Ware, Miller adds, 'Iâm 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 whatâs 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.ä

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 states, 'It has been nice having that remote site where we have Flo-Dar permanently set up. We can now take that experience and knowledge and run with it.ä

The Hazel Dell Maintenance Crew

The Hazel Dell Sewer District is currently involved in a long-range I&I planning effort. Miller adds, 'Data from the Flo-Dar meters will provide critical information that will go into that effort.ä As the District continues to see rapid growth, they can count on their investment in innovative flow instrumentation from Marsh-McBirney to provide accurate flow data that in the end will provide savings for their entire flow monitoring program.