Transcript RECORDING WATER TABLE DYNAMICS T & D Project No. 1E11EM35 Setup, Installation, Comparison USDA FOREST SERVICE Technology & Development Center 444 East Bonita Avenue San Dimas, CA 91773

RECORDING WATER TABLE DYNAMICS
T & D Project No. 1E11EM35
Setup,
Installation,
Comparison
USDA FOREST SERVICE
Technology & Development Center
444 East Bonita Avenue
San Dimas, CA 91773
Setup and Installation
Materials
• Well screen and point suitable for soil type
– Sandy soils often require metal points, screens and pipe to
allow driving the well appreciably below immediate water
table
– Soils not susceptible to sloughing below the water table will
accept PVC points, screens and pipes without excessive
driving
• 2” pipe (UV-resistant preferred if PVC), 2” slipconnect unions, and pipe cement
Setup and Installation
Materials
An effective well screen is essential for
accurate water table measurements. This
provider determined appropriate screen size
based on a description of the soil type.
Brady Products, Inc.
2151 Logan St. P.O. Box 5304
Clearwater, FL 34618
Toll free (800) 237-6900
Florida (800) 282-6900
Setup and Installation
Materials
• Data logger unit designed for 2” well (all units tested
are acceptable)
• Metal locking well cap, mounting screws, screwdriver,
drill, and lock
• Well auger, well screen, slide hammer suitable for
driving pipe below water table, saw suitable for cutting
pipe to length
• Laptop or palmtop computer for testing and setting up
units after installation
Setup and Installation
2-⅜ ”
2-⅜ ”
Well cap base secured to PVC pipe by
short machine screws. Screws are
securely shrouded by locking well cap.
Setup and Installation
Locking well cap provider
• Royer Quality Castings, Inc.
380 S. Reading Ave. (Rear)
Boyertown, PA 19512-1812
(610) 367-1390
Fax (610) 367-8435
-Padlocks and keys available from same supplier
Setup and Installation
The caps received required
some grinding to remove burrs
left over from casting.
Setup and Installation
All units tested are compatible with 2” well diameters.
Ordering options generally include various cable lengths.
All cables can be shortened considerably by winding extra
cable around a ½” diameter stick at the top of the well (see
next slide).
Setup and Installation
The InSitu sensor is the only sensor that can be detached
from its cable in the field. This allows the installer to carry
several cable lengths for one sensor when water table
depths are not known before installation. This reduces
the need to wrap cable.
Sensors must be suspended
above the bottom of the well.
Pipes frequently need to be
driven several feet below the
water table to allow accurate
measurement at greatest depth.
Setup and Installation
The unique suspending collar installed on the In-Situ cable required an alternative
installation to allow later retrieval without destroying the well. The plastic locking
well cap provided with the unit inspired little confidence in the unit’s security,
though the company is interested in providing metal locking caps on demand.
Setup and Installation
Notice the two locks necessary to allow nondestructive removal of the In-Situ unit (left). The Sutron
logger head (center) requires the tallest well stack to allow measurements up to ground level. The
Global requires a considerably shorter stack, and the In-Situ would require nearly no stack (and
only one lock) if the cable was not coiled inside. Coiled cable and cable ends must be suspended
above the highest possible water level.
2-Inch Well Compatible Equipment
Tested Models
• In-Situ MiniTROLL
• Sutron DWLMS
• Global Water WL15
Untested Models
• Unidata 8007WDP
• Solinst Levelogger
– No pressure compensation
• Stevens SDI-12 Depth Sensor
– Logging option not designed
for 2” well
• Vadoscan water level sensor
– Inadequate memory
This is not a comprehensive listing. The above products are a
sampling of those commercially available at the time of the project
market search.
Unit Comparisons
• Palmtop data collection with In-Situ unit
allows more convenient monitoring in all
conditions
• Global Water also releasing palmtopcompatible software
• Global unit contains no desiccant to replace
• Sutron log records errors and notes as well
as data
Unit Comparisons
• In-Situ data management more userfriendly; much more difficult to accidentally
lose data
• Installation of all units much easier when
coiling cable can be avoided