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Dewatering and groundwater control | Stuart Well Services Ltd

Filter Materials

Air Sparging

When building an efficient well for groundwater monitoring or abstraction you should consider the filter material surrounding the well liner.

Filter Materials

Washed, bagged and dried filter materials are available either as natural silica sands or Glasmedia, made from recycled glass. Both are ideal media when building an efficient well for groundwater monitoring or abstraction. They allow largely unrestricted flows of groundwater into the well while simultaneously preventing the ingress of soil particles (other than those during the initial development phase) and supporting the water-bearing formation.

Informed judgment must be made regarding the wellscreen slot sizes, the filter material and the encountered ground conditions to obtain the correct borehole construction. Please enquire for more details.

Silica Filter Sands

These materials from non-sustainable materials are available in graded sizes as in the tables below:

Size Weight Part No.
0.5 - 1.0mm sand x 25 kg BFS-51
1.0mm - 2.0mm sand x 25 kg BFS-12
2.0mm - 4.0mm x 25 kg BFS-29
3.0mm - 5.0mm x 25 kg BFS-53-5
5-8mm Single Size x 25 kg BFS-58

Industrial Dried Silica Sands

British Sieve No. 0.5 - 1.0 mm 1.0 - 2.0 mm 2.0 - 5.0 mm
4 - - 96.2
5 - - 83.4
6 - - 56.4
7 - - 31.2
8 - 98.3 6.9
10 - 78.6 2.6
12 99.8 52.3 -
14 98.7 27.0 -
16 74.5 6.0 -
18 44.8 0.2 -
22 15.2 - -
25 4.9 - -
30 0.6 - -

Glasmedia

Glasmedia is manufactured from sustainable recycled material container glass (graded silicate glass sand) in the United Kingdom and diverts unwanted glass from being landfilled. During the manufacture the recycled glass is imploded using ultra sonic sound waves to produce a smooth particle shape. The product is not sharp, you can actually rub it in your hands quite safely.

The glass particles are washed to ensure they are clean and free from contamination from their previous use. The Glasmedia is hot air dried and graded in to 25 kilogram recyclable plastic sacks.

Percentage Passing

Percentage Passing

Mesh mm BG12(1.0 - 2.0mm) BG25(2.0 - 5.0mm) BG36(3.0 - 6.0mm) BG610(6.0 - 10.0mm)
1.0 4.9 - - -
1.3 41.70 - - -
1.4 70.40 - - -
1.6 93.00 - - -
2.0 100.00 1.70 - -
3.0 - 23.40 4.28 -
4.0 - 68.20 50.70 -
4.5 - 91.00 76.40 -
5.0 - 97.00 83.50 0.00
6.3 - 100.00 100.00 14.00
7.1 - - - 57.10
8.0 - - - 77.40
9.0 - - - 88.80
10.0 - - - 99.00

Glasmedia is able to offer the additional benefit of contributing significant quantities of recycled materials during the development of new buildings with geothermal installations and during dewatering works. This benefit should be highlighted with your tender submissions as it may just tip the contract in your direction. For example if you are installing 10 No. 32mm loops to 100metres within a 6" drilled well with Glasmedia installed to 10 m bgl, this would equate to the use of 23,000 kilograms of recycled materials.

Size Weight Part Number
0.5 - 1.0 mm sand x 25 kg BG51
1.0mm - 2.0 mm sand x 25 kg BG12
2.0mm - 5.0 mm x 25 kg BG25
3.0mm - 6.0 mm x 25 kg BG36
10mm Single Size x 25 kg BG610

Additional benefits of Glasmedia include the silica content existing in a bound form, providing no health risk; plus the product is less dense than conventional filter sand so less materials are required to back fill the annulus.

The table below indicates the bags required to back fill with assuming no voids within the drilled hole quantity of filter materials:

6" 150 mm - 19 mm 1.04 bags
- 150 mm - 35 mm 1.00 bags
- 150 mm - 50 mm 0.94 bags
8" 200 mm - 50 mm 1.74 bags
- 200 mm - 100 mm 1.39 bags
- 200 mm 6" 150 mm 0.80 bags
10" 250 mm 4" 100 mm 2.53 bags
- 250 mm 6" 155 mm 1.87 bags
- 250 mm - 200 mm 1.14 bags
12" 300 mm - 100 mm 3.79 bags
- 300 mm - 155 mm 3.13 bags
- 300 mm - 200 mm 2.40 bags
- 300 mm - 200 mm 1.26 bags
14" 350 mm - 100 mm 5.29 bags
- 350 mm - 155 mm 4.63 bags
- 350 mm - 200 mm 3.90 bags
- 350 mm - 250 mm 2.76 bags
16" 400 mm - 155 mm 6.43 bags
- 400 mm - 200 mm 5.70 bags
- 400 mm - 250 mm 4.56 bags
- 400 mm - 300 mm 3.30 bags

Geotextile Filters for Wellscreens

Installation of well liners when all ground conditions are unquantified still presents problems due to fine sands and silts that may be present. There is the risk that these will migrate into the well causing it to silt up with the associated costs of redrilling.

A practical solution to this common problem is the use of geotextiles which are applied over the slotted well liner after machining into a tube. The benefits of the geotextile allow for the unexpected that can be encountered during site investigations.

The geotextiles are highly chemical resistant with a high tensile strength and a high transmissivity.

Available in a range of sizes and manufactured to fit any pipe size from 19mm to 630mm diameter.

Geotextile Filters Specifications

Part No. D85   D200  
Pore Size 85   200  
Weight g/m2 140   160  
Thickness(mm) 0.95   1.00  
CBR Test 1335   n/a  
Fall Cone Test 32   n/a  
Water Permeability 10   48x10  
ltrs/second/m2 150   180  
Specific Weight 0.90   1.30  
Trade Name F-2B   GEOSOCK  
* - TER 1000 and HF-400 are special order items

An outer protective netting can be fitted to protect during transportation and installation within the borehole.

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