User Guide

High Quality Groundwater and Surface Water Monitoring Instrumentation
The seal around the probe does not have to be
airtight, but the signal works better when the
sound waves cannot escape and it also helps
prevent external noise, such as wind, from
interfering with the sound wave.
2) Limit and account for the
diameter of the well you are
measuring in
The Solinst Sonic Water Level Meter works
best in wells or pipes with diameters of 8" or
less.
This is because, as well diameter increases,
the strength of the sounds pulse weakens.
Therefore, the pulse is more susceptible
to pump noise or interference from other
imperfections.
As such, wells larger than 8" in diameter
should use a drop tube from top of well, to
below the depth to water for measurement.
SOLINST TECHNICAL BULLETIN
5 Tips for Getting the Most Accurate Readings
from a Sonic Water Level Meter
...continued overleaf
®
Solinst is a registered trademark of Solinst Canada Ltd.
When should a Sonic Water Level
Meter be used?
Since the Sonic Water Level Meter works at the
surface, and there is no need to lower anything
down well, it is perfect for use in some specific
scenarios:
• In crooked or obstructed wells where
equipment can potentially be entangled
• At contaminated sites (concerns of
cross contamination from well to well
and decontamination of equipment)
• On sites where equipment is not allowed
to enter the well or touch water surface
• When fast manual single point
data collection is required
• In narrow, cascading, or difficult
to access water level wells
Generally, when using a Sonic Water Level
Meter, it is preferable if you already know some
information about the well, borehole, pipe, or
piezometer that you are measuring in.
If you are unfamiliar with your monitoring
environment, you may want to consider using
a standard Water Level Meter instead. Solinst
offers a range of Water Level Meters that may
be better suited to your application.
Solinst Water Level Meters feature an accurately
marked tape every millimeter or 1/100th of
a foot, so you are ensured that accuracy. An
audible tone and light confirm you have hit
water, and not some sort of obstruction in the
well.
Sonic Water Level Meters can provide
accurate depth to water level
readings, especially if you follow the
tips discussed next.
1) Ensure your well has the proper
setup
If the top of your well or pipe is open, then it
should be covered with a cap with a hole for the
probe to access. Solinst includes a plastic disc
with each Sonic Water Level Meter, providing a
good option for covering larger well openings.
Since the pulse generated from the Sonic Water
Level Meter probe is an air pressure wave/
low frequency sound wave, there should be a
good seal around the probe to prevent the air
pressure from escaping the well, which can
result in losing/weakening the pulse.
How Does a Sonic Water Level
Meter Work?
The Solinst Sonic Water Level Meter
works by a probe at surface transmitting
a low frequency sound wave into a
pipe, tube, or well, and measuring the
time it takes for the pulse to return
after making contact with water.
The depth to water is calculated using the
speed of sound and time. The depth to static
water level is displayed on the LCD screen
of the control unit after just a few seconds.
The accuracy of the reading depends on
the acoustics of the well, which can be
affected by anomalies like cracks in well
casing, collars, borehole protrusions or
irregularities, or other instruments down the
well. It also depends on how well you know
the environment you are monitoring, and
if you set up your Sonic Water Level Meter
properly.
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