Measurement Plansand

Measurement Variances

Upper Wood Rivers Water Measurement District

Flow Meter WorkshopJanuary 27, 2012

Confirms owner or operator of a well

Documents a water user’s intentions to install a standard magnetic flow meter, or provides opportunity to request a variance of the mag requirement

Allows hydrographer or IDWR to make an initial evaluation of a diversion system for variance approval or denial

Ensures correct installation of flow meters

Why Measurement Plans?

A full-profile magnetic meter which appears on IDWR’s List of Approved Electromagnetic Meters

Any other full profile magnetic meter which meets IDWR’s minimum criteria (users bears the risk the meter will perform as rated)

Minimum Criteria:Flow range 0.1 – 33 feet per second Manufacturer accuracy ± 2%, repeatability ± 0.5% of reading Display which registers both rate and totalized volume Display must be programmable, non-resettable, and have sufficient number of

display digits and units of volume that the totalizer will not “roll over” within a two year period.

Insertable magnetic flow meters are NOT standard meters and use must be approved through the variance process

Acceptable Standard Flow Meters

Development of a Power Consumption Coefficient (PCC), a ratio of power usage to water withdrawal (qualifying irrigation diversions only).

Use of an hour meter or time clock (qualifying diversions only).

Use of an existing operating flow meter (installed prior to the date of the measurement order) if that meter meets accuracy tests.

Use of an acceptable non-standard flow meter where it can be shown that installation of the standard meter would be burdensome (diversions with pipe sizes > 12”, other special cases).

Acceptable variances have NOT YET been fully determined for small users.

Variances to the Magnetic Meter Requirement

1. Power Consumption Coefficient (PCC) - a ratio of power usage to water withdrawal.

PCC may only be used where this ratio is constant.

PCC is invalid under any of the following conditions: the presence of secondary loads on the power meter UNLESS

they always run with the well. artesian flow, variable frequency drives or non-electrical

energy sources which can’t be reliably measured variable diversion rates and/or pressures, or changing water

levels over the irrigation season

Variances to the Magnetic Meter Requirement

How Many Pumps can you Count?

1

2

3 4

2. Hour meters or time clocks – measure the total time the pump has operated over the season.

This method is suitable for pumped wells which open-discharge into a pond, ditch, or cistern

Flow discharge must be steady and must not increase or decrease through the season

Flow must be measured by the hydrographerPump must not be throttledClock must be wired into the main pump control, and must be

mounted on the outside of the panel.

Variances to the Magnetic Meter Requirement

3. Use of an existing operating flow meter.

Meter must have been installed prior to the date of the measurement order

Existing meters will be field tested and must be accurate to ±10% of actual rate and volume when compared to a certified portable flow meter

Meter must be installed properly, have a non-resettable totalizer and suitable units of rate and volume

If the meter fails, or ceases meeting the accuracy test, it must be replaced with a magnetic meter

Variances to the Magnetic Meter Requirement

4. Use of an acceptable non-standard flow meter with an approved variance only.

For diversions with pipe sizes > 12: Insertable magnetic meters – limited to those systems where flow

is not variable Vortex meters – highly accurate but expensive, usually reserved

for industrial applications Ultrasonic or acoustic doppler meters – accurate over a wide

range of flow in very large pipe

Under consideration for small users on pipe sizes ≤ 2”: Ultrasonic clamp-on or spooled types Positive displacement or mutating disk (aka city service meters)

Variances to the Magnetic Meter Requirement

So, how do I complete my plan??