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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 material is available as a natural silica sand, ideal for use when building an efficient well for groundwater monitoring or abstraction. This allows 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 BFS51
1.0mm - 2.0mm sand x 25 kg BFS12
2.0mm - 4.0mm x 25 kg BFS24
3.0mm - 5.0mm x 25 kg BFS35
5-8mm Single Size x 25 kg BFG58

Industrial Dried Silica Sands

British Sieve No. 0.5 - 1.0 mm 1.0 - 2.0 mm 2.0 - 4.0 mm
4 - - 100
5 - - 99.8
6 - - 79.3
7 - - 24.1
8 - 98.3 3.6
10 - 78.6 1.0
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 - -

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 225mm diameter.

Geotextile Filters Specifications

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  

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

Accreditations and Associations

ISO-9001 ISO-14001
ISO-22301 ISO-45001
The Temporary Works Forum (TWf)