Enviroscopics Visual Clarity Wedge
aka: Turbidity Wedge / Secchi Wedge
VISUAL CLARITY WEDGE
/ TURBIDITY WEDGE
The Enviroscopics Visual Clarity Wedge (EVCW) or Secchi Wedge is an inexpensive
supplement to the electronic turbidimeter and can be used for estimating and
tracking changes in turbidity levels.
tool is the improved evolutionary descendant of the Triton Turbidity Wedge, which was
developed by the same designer for water quality monitoring on the Vancouver
Island Highway Project and has been in use by environmental professionals in the
private and public sectors for the past 8 Years.
Continuous rather than incremental scale.
Sliding cursor with "Secchi Disc" type target pattern produces more
objectivity in the determination of values.
Direct measurement in cm and direct approximations of Nephelometric Turbidity Units (NTU).
Tougher construction (1/4" Acrylic body)
its pre-cursor, the EVCW is used to measure the distance to extinction of an
image by horizontal viewing through a fluid contained within the vessel.
The vertically tapered body with opposing viewing window and target plate
allows for a range of viewing distanced from 0 to 20 cm. This provides for an approximation of turbidity values from about 50 NTU
the former unit, in which the target plate was also the reading scale, this unit
uses a moving "Secchi Disc" type target design, which requires the
measurement to be set prior to being read which must be done by looking at the
reverse side of the instrument.
moving target, while being designed after a well established pattern in use for
many years in the Secchi Disc, provides a much more effective visual cue than a
static pattern as our visual sense is stimulated by movement. When moving the target back and forth through the medium, we can either
see the movement or not. In
contrast, looking at a static, repeating pattern, fading gradually out of sight,
can be confusing, as our brain is very good at filling in missing information
1) The wedge, being a
manual tool contains no batteries or sensitive electronics, prone to break down
under rugged field conditions.
2) It can be used as a routine measuring tool or as a back-up to electronic
As well as providing a measurement of turbidity, the tool provides an
opportunity for observation of other characteristics of the sample material such
as the types of suspended and floating or settling material, colour etc.
Hands on contact can help to eliminate a tendency common to electronics of
providing unfounded numbers that may be the result of instrument malfunction or
Cost is less than 1/10 that of an electronic instrument
WATER QUALITY LINKS
Charles Newcombe of the BC
Ministry of Water Land and Air Protection has made available a downloadable
pdf copy of the following water quality documents at the
provincial government ftp site.
1) Impact Assessment Model
for Clear Water Fishes Exposed to Excessively Cloudy Water, Published
in June 2003 in the Journal of American Water Resources Association
2) A two page field
reference manual, suitable for high quality printing and lamination
To Access, click on the
You will want all 3 files
Pacific Stream Keepers Kit
Streamkeepers Program has assembled equipment kits at several locations in
the province. These kits contain benthic invertebrate samplers, water
quality test kits, and surveying supplies.
IN THE NEWS
Clampdown on miners muddying waters,November
Welcome to guyanachronicle.com sports
... up its monitoring
measures through the introduction of a turbidity wedge.
to have each mining camp equipped with a turbidity wedge
by January 2004. ...
ENVIRONMENTAL ASSESSMENT OFFICE KNOB HILL WIND FARM ASSESSMENT REPORT
File Format: PDF/Adobe
View as HTML
... events during major rainstorms, using an Enviroscopics