When building an efficient well for groundwater monitoring or abstraction you should consider the filter material surrounding the well liner.
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.
These materials from non-sustainable materials are available in graded sizes as in the tables below:
|0.5 - 1.0 mm sand||x 25 kg||SWSFS1|
|1.0mm - 2.0 mm sand||x 25 kg||SWSFS2|
|2.0mm - 5.0 mm||x 25kg||SWSGM3|
|3.0mm - 6.0 mm||x 25kg||SWSFS4|
|10mm Single Size||x 25kg||SWSFS5|
|British Sieve No.||0.5 - 1.0 mm||1.0 - 2.0 mm||2.0 - 5.0 mm|
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.
|Mesh mm||swsgm2(1.0 - 2.0mm)||swsgm3(2.0 - 5.0mm)||swsgm4(3.0 - 6.0mm)||swsgm5(6.0 - 10.0mm)|
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.
|0.5 - 1.0 mm sand||x 25 kg||SWSGM1|
|1.0mm - 2.0 mm sand||x 25 kg||SWSGM2|
|2.0mm - 5.0 mm||x 25kg||SWSGM3|
|3.0mm - 6.0 mm||x 25 kg||SWSGM4|
|10mm Single Size||x 25kg||SWSGM5|
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:
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.
|Fall Cone Test||32||28||n/a||12|
|Trade Name||F-2B||TER 1000*||GEOSOCK||HF - 400*|
|* - 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.