ADS 507165, Installation, Operation And Maintenance Manual, Page: 210 / 535

5-4 ADS Manual
Investigating Site Characteristics
Before beginning installation activities, conduct a thorough
investigation of hydraulic and site conditions.
Flow Hydraulics
The hydraulics of a site directly affect the monitor's ability to
accurately measure flow depth and velocity. The following
characteristics indicate when a site exhibits hydraulic conditions
favorable for effective flow monitoring activities:
z
Relatively Smooth Flow with Central Peak Velocities
The potential site should exhibit minimal ripples or waves.
Choppy or foamy flow will adversely affect sensor accuracy.
Bulging pipe joints, upstream curves, or upstream merging of
pipes can contribute to choppy surfaces and off-center peak
flow velocities. However, please note that a limited degree of
roughness in the flow is necessary to ensure the sensor signal
can adequately reflect off the flow surface.
z
Absence of Significant Silt Buildup at Pipe Bottom
Silt present at an otherwise favorable site must be accounted
for to obtain accurate flow measurements. The sensor may
require positioning up the side of the pipe to ensure it remains
out of the silt.
(Refer to Installing the Ring in the Pipe on page
5-28.)
z
No Evidence of Surcharging Debris present on ladder
rungs or joints in the manhole may indicate the site experiences
surcharging. If this occurs on a regular basis, consider finding
an alternate location for monitoring if mounting the sensors in
the pipe to measure flow rate.
z
Relatively Quiet Pipe A monitoring point in a pipe
experiencing loud noises, such as active drop connections, can
adversely affect the accuracy of air ultrasonic depth
measurements.