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Installing

the WECSA Soil Access System

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The WECSA Soil Access System (WESAS) (U.S. Patent 5,578,769) is designed for long-term in situ soil chemical monitoring with UNIBEST, Inc. resin capsules (U.S. Patent 5,355,736).

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An access tube (Figure 1) has a casing with a cap and removable capsule carrier assembly that fits inside the casing.

Access System Assembly
Figure 1. WECSA soil access system components.


The patented placement of WECSA access tubes in the ground, at an angle, permits several tubes to be used together to reach multiple depths in a soil column (Figure 2).

Installation Diagram
Figure 2. Installation diagram.

Using an auger guide
Figure 3.  Using an auger guide to make an installation hole.

  • Place a marker over the vertical line of sample points.

  • Measure the surface offset distance using the appropriate value from the installation measurements table.

  • At the offset point, use a 3.8-cm (1.5-in) diameter auger to make a hole at a 60° angle from horizontal (30° from vertical), toward the surface mark (Figure 3), to the length marked on the access tube. I am using a stainless steel bucket auger with an 11.5-cm (4.5-in) long barrel from Art's Manufacturing & Supply, Inc.

It is important to carefully clean the auger before removing the last 2.5-cm (1-in) or so of soil, in order to provide a clean hole.

  • Place the WESAS casing in the hole (Figure 4) so it is seated at the depth marked on the tube.

Install WESAS casing
Figure 4. Installing WESAS casing.

A resin capsule must be in close contact with the soil to adsorb ions or other compounds from the soil solution. This means a hemispherical cavity needs to be created at the bottom of the access hole. A capsule seat bit, available through WECSA, (Figure 5) provides the correct geometry and permits vacuuming the remaining soil in sandy or dry conditions.

Capsule Pocket Bit
Figure 5. An auger bit to create a pocket for proper capsule seating.

Cleaning access hole with capsule pocket bit
Figure 6. Using a modified leaf blower with the capsule pocket bit to vacuum the access hole.

  • Change auger bits, remove the casing cap, and make a 2-cm (3/4-in) diameter, 2.5-cm (1-in) extension of the hole from inside the casing. This is where the resin capsule is placed. Use care to maintain a clean hole (Figure 6).

Always handle the resin capsules according to the protocol for the capsule you are using. Make sure that the gloves you use do not have any surface treatment or contaminants. Check with your glove supplier or manufacturer to obtain a suitable product. Use a plastic tweezer for inorganic and a stainless steel tweezer for organic sampling (Figure 7).
  • Unscrew the capsule retainer retainer on the carrier assembly.
  • Seat the capsule in the socket so that the flange extends beyond the edge (Figure 7).
  • Carefully place the retainer over the capsule flange and tighten firmly.

Placing capsule on carrier
Figure 7. Using a tweezer to place capsule on the carrier.

  • Place the carrier into the casing (Figure 8) and firmly seat the capsule in the pocket that was prepared.
  • Screw the cap over the spring so that it is snug but not tight.
  • To exchange capsules, remove the casing cap, remove the carrier, wash all soil from the capsule with pure water, remove capsule, place in a suitable container, and replace with a new capsule.

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Inserting capsule carrier
Figure 8. Placing capsule carrier into the WESAS casing.

Installation Measurements
WECSA Soil Access System

Metric (Centimeters) English ('=Feet / "=Inches)
Sample
Depth
Surface
Offset*
Sample
Depth
Surface
Offset*
10 5.8 0' 4" 2.31"
15 8.7

0' 6"

3.46"
20 11.5

0' 8"

4.62"
25 14.4

0' 10"

5.77"
30 17.3

1' 0"

6.93"

35 20.2

1' 2"

8.08"
40 23.1

1' 4"

9.24"
45 26.0

1' 6"

10.39"
50 28.9

1' 8"

11.55"
55 31.8

1' 10"

12.70"
60 34.6

2' 0"

13.86"
65 37.5

2' 2"

15.01"
70 40.4

2' 4"

16.17"
75 43.3

2' 6"

17.32"
80 46.2

2' 8"

18.48"
85 49.1

2' 10"

19.63"
90 52.0

3' 0"

20.78"
95 54.8

3' 2"

21.94"
100 57.7

3' 4"

23.09"
105 60.6

3' 6"

24.25"
110 63.5

3' 8"

25.40"
115 66.4

3' 10"

26.56"
120 69.3

4' 0"

27.71"
125 72.2

4' 2"

28.87"
150 86.6

5' 0"

34.64"
170 98.1

5' 6"

38.11"
180 103.9

6' 0"

41.57"
200 115.5

6' 6"

45.03"
215 124.1

7' 0"

48.50"
230 132.8

7' 6"

51.96"
245 141.5

8' 0"

55.43"
260 150.1

8' 6"

58.89"
275 158.8

9' 0"

62.35"
290 167.4

9' 6"

65.82"
305 176.1

10' 0"

69.28"
* Install at 30-degrees from vertical, 60-degrees from horizontal.
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Decimal Equivalents

Following is a decimal equivalents table for your use in converting to fractions of an inch. My plea to all of you who still cling to the English system of measurements, please change to Metric--it is so much easier to use.

DECIMAL EQUIVALENTS

Decimal Fraction Decimal Fraction Decimal Fraction Decimal Fraction
.016 1/64 .156 5/32 .438 7/16 .875 7/8
.031 1/32 .172 11/64 .500 1/2 .938 15/16
.047 3/64 .188 3/16 .531 17/32 1.000 1
.063 1/16 .203 13/64 .563 9/16 1.125 1-1/8
.078 5/64 .219 7/32 .594 19/32 1.25 1-1/4
.094 3/32 .250 1/4 .625 5/8 1.375 1-3/8
.109 7/64 .281 9/32 .688 11/16 1.500 1-1/2
.125 1/8 .313 5/16 .750 3/4 1.625 1-5/8
.141 9/64 .344 11/32 .813 13/16 1.750 1-3/4
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Gordon Warrington
WECSA
419 Flathead, Unit 3
PO Box 489
Saint Ignatius  MT  59865-0489
U.S.A.

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Gordon@wecsa.com
Phone  (406) 745-0160
Last Update 2-2-2006
Copyright 1998 - 2006