In-Situ Oil/Water Interface Meter Instruction Sheet - Manual (Page 3)

Page 3
Problem
The unit makes a continuous sound when the probe
enters the well while not in water or LNAPL.
Solution
Check to make sure that the lens is clean. Remember
the unit is silent in daylight. Check for scratches on the
lens. A badly scratched lens may cause the instrument to
malfunction. See also Cold Weather under General Hints
on Page 1.
Problem
In heavy LNAPL, it is difficult to discern the oil/water
interface.
Solution
Apply a small amount of liquid dish washing detergent
onto the lens and probe body. Slowly lower the probe
into the well to determine the top of the LNAPL layer.
Perform this action until you achieve a steady reading.
Pass the probe through the LNAPL into the water. The
small amount of detergent helps the probe to quickly
shed oil. Slowly raise the probe to determine the
underside of the LNAPL layer.
Problem
At times a steady tone is emitted at the surface of the
water in a well that has no LNAPL.
Explanation
The most accurate reading is made when the probe
goes down the well and first contacts the fluid surface.
When the probe is raised out of the well through the
fluid, you can get a less representative reading due to
hysteresis and the meniscus effect. As the probe passes
from water to air, fluid draining down the outside of the
tape and probe can affect readings.
Question
Why do I hear a signal when the probe is coming out of
the well but is no longer in fluid?
Answer
Small amounts of fluid may be draining down the
probe and over the probe and lens. This could cause a
sporadic signal to be given. These stray signals should
not be confused with the LNAPL and water signals.
Problem
I tried to measure the water level in a cascading well
using the interface meter, and I heard a continuous
signal both in and out of the water.
Solution
These units can be used as expensive water level
meters, but they have not been designed for use in
cascading wells. The water running over the lens can
cause the unit to signal LNAPL. Using the probe shroud
can help prevent this problem. You can purchase a
probe shroud by special order.
Question
Why does the unit stay on for only 5 minutes?
Answer
Unlike a water level meter, the interface meter uses
power continuously. The automatic shutoff is a
safeguard in case the user forgets to switch off the unit
after use.
Question
Will the instrument detect DNAPLs?
Answer
Yes.
Question
Can the instrument be lowered to full tape depth in the
well?
Answer
Yes, although we advise against this. The probe will
withstand the pressure at depth, but damage to
the probe or accumulations of mud may affect the
operation of the unit.