Thurston County Comments
on Greyline Area-Velocity Flowmeters

Hydrodynamic Area-Velocity Sensor
Greyline Area-Velocity
Flow Sensor

“Thanks for the good work and
 the years of success we have
 had with Greyline...”

  Mark P. Biever, Water Resources Group
  Thurston County, Washington


We have been using Greyline products at Thurston County, Washington for approximately seven years. We use both the Stingray portable flow meters and the permanent Area Velocity Flow Meter (AVFM II) in multiple stormwater applications. We have used these meters to measure stormwater flows to help our design engineers develop flow capacity for stormwater projects. We have deployed the Stingrays at multiple locations within our stormwater facilities to gauge the effectiveness of our designs and construction methods. Our engineers accomplish this by deploying the Greyline systems a minimum of one year before construction (during the design phase) and one year after construction to evaluate the pre and post construction periods. When the job has been completed we move the stingrays to another location and begin again.

In addition to the multiple uses of the Greyline Stingrays, we have also used the more robust, permanent installation of the AVFM II for long term deployment in one of our permitted discharge sites. The flows that this instrument monitors and records is directly related to the discharge fees payed by Thurston County to the local wastewater treatment utility. An accurate measure of the discharge quantity equates to real dollars because this facility is billed by the gallon and by the rate of discharge into the municipal system. In this situation, Thurston County relies on the accuracy of the AVFM II to provide highly accurate flows in an in-pipe banded flow meter assembly. The system has been in continuous operation since late 2010. For this application we also decided to use the very low flow ultra sonic level meter add on because at times the flow is very turbid and very slow, therefore we wanted to maintain peak accuracy even in adverse conditions.

Prior to installation of the AVFM II, the plant operator used a interpolated chart to average how much waste water was flowing into the municipal system. This method resulted in overpayment by thousands of dollars per year. We were able to inform them that they had been grossly overestimating their summer discharge volume based on the results from AVFM II data that is continuously collected. They now pay submitting exact volume measurements that they can verify.

Although Thurston County does use various types of flow meter vendors depending on the specific job, we have always had great luck and service dealing with Greyline and their local vendor in helping us meet our flow monitoring needs and have recommended Greyline to other local agencies and consultants for their specific projects as well.

I don't hesitate to use the Greyline products and have always had good luck with the quality and results of the Greyline products. Thanks for the good work and the years of success we have had with Greyline and your local representatives.

Mark P. Biever
Environmental Monitoring Program Supervisor
Thurston County, Washington

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