Water Drilling
Underground Water | Water Resources Act 3 | Site Selection | Water Requirements | The Bore Hole | Casing | Mud Drilling
Bore Construction | Drilling Equipment | Costings | Client Rate Sheet | Pump Testing
Equipping the Bore | Types of Pumps | Salinity Chart
UNDER GROUND WATER
In simple terms, under ground water is described as water occurring at various depths
below the surface. Although there are different types of under ground water, the most
common is derived from rainfall and is constantly being recharged, dependant on
rainfall within the area. The underground areas where water is found are known as
aquifers.
Although there are enormous sources of under ground water, its quality varies very
greatly. This is usually judged on its degree of salinity (or salt content, see tables on
page 16) and ranges from "fresh water of 100 milligrams per litre (mg/l or less to
brines of 300,000 mg/l or more).
The quality or volume of flow which can be expected from a bore greatly depends
on the type of material and its porosity or ability to not only contain water but also
to yield it. For instance, clay has high porosity but a very low yield rate. Generally in
the Mount Lofty Ranges area, water is contained within the fractures of hard rock
(see illustration page 7), and usually the water is of good quality. Due to the high
rainfall within this area the recharge rate is also very good, ensuring permanence
of supply. However, in some isolated instances, an initial good supply of water is
found, but the supply lacks permanence.
This situation can usually be detected by
having the well pump tested. The company takes regular samples of
materials and water during the course of drilling which can give indications of quantity
and quality of water.
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WATER RESOURCE ACT PERMIT
The Act which came into effect in 1976 is designed to protect the State's water
resource and is administered by the Department for Water .
The Act states a Licensed Driller is required for work on all water wells deeper than
2.5 metres, and that a permit be obtained prior to the commencement of any work.
Permit applications can be obtained from the Department or through the company
who can assist you in filling in the permit application form. A Government lodgement
fee applies for each permit application.
In many areas a License to Extract Water
is required when water is intended for irrigation purposes, the normal Permit applies for water required for stock and domestic use
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SITE SELECTION
There are many factors which must be taken into consideration prior to selecting a
site and it is suggested that advice be sought on this matter. Listed elow are
suggestions for your guidance.
FRANK WALSH DRILLING (S.A.) PTY. LTD
At the time of a site inspection the Company representative can assist in site selection based on local knowledge and the practicality of equipment access.
GROUNDWATER CONSULTANTS
Groundwater consultants are hydro-geologists or engineers experienced in working
with under ground water. They can be hired to give advice about the prospects
of obtaining a supply in your area, plus detailed information about well siting, and
production testing of the completed well. Names of groundwater consultants can
be supplied by the Company.
WATER DIVINERS
The Company has drilled many very successful bores on sites determined by
water diviners, who usually select the site with the aid of a divining rod.
Water
diviners generally specialise in particular areas. Should you wish to engage the
services of a diviner, names and addresses can
be supplied by the Company.
DEPARTMENT OF WATER
Information on all known water supply bores is available from the Department,
enabling an assessment of general water prospects to be made for a
particular area. (a fee is charged for this information).
INTERFERENCE BETWEEN BORES
When water is pumped from a bore, water levels in the area around are sometimes
lowered. This could effect any adjacent bores in close proximity, it
is as well to
check on proximity of other bores, particularly if not on your property, and to seek
advice from the company or groundwater consultants on any possible effects.
S.A.ENVIRONMENT PROTECTION ACT
During the course of drilling a bore, wastewater is discharged containing sediment,
and in some instances foam and additives. This water must not be released into
a watercourse (even if dry), wetlands, channels, wells or close to the bank of a
watercourse, as it may be causing environmental harm; thereby committing an
offence under Part 9 of the S.A. Environmental Protection Act. Should you have
concerns that your proposed bore site could constitute a problem and cause
pollution, advice can be sought from the Environmental Protection Authority in
consultation with the Company. In some instances it could be necessary to
construct a temporary lagoon where wastewater can be disposed of by natural
evaporation or filtering devices can be introduced.
POWER SUPPLY
It should be born in mind that if you equip your bore with an electric pump, the
cost of bringing power to the site could form a major cost in the equipping of a
bore. If possible the site should be selected as close as practical to power supply.
ACCESS
Even though drilling rigs are fairly large, heavy vehicles, their special design and
the expertise of the operators enables most sites to be accessible. However
reasonable access must be provided. If in doubt the Company will check prior to
the location of the site being finalised.
FIRE AND SAFETY CONDITIONS
During the course of drilling a bore it is often necessary to use welding equipment
which produces a naked flame. It is recommended that inflammable material be
removed within a radius of 4 metres from the site prior to the arrival of the drilling
equipment. Should there be any low power lines in close proximity to the site, it
is requested that power be turned off during siting of equipment and actual drilling.
(Mast height of rig 15 metres).
POLLUTION
To avoid any possibility of pollution the bore should always be sited as far away
as practical from drainage wells or septic systems.
UNDERGROUND PIPES, CABLES ETC.
It is the client's responsibility to investigate and clearly mark the location of all
underground cables, wires, pipes or other services that could conflict with the
drilling of any hole. No responsibility will be accepted by the Company for damage
to or repair of any pipe, cables, etc., not clearly marked. The Company can advise
you, when determining the site, of the various bodies that should be contacted.
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WATER REQUIREMENTS
Prior to the commencement of any bore, calculations should be carried out as to your
annual water requirements, bearing in mind that the findings from a Tested Bore' will be
shown as litres or gallons per hour. For instance, a domestic bore showing, at test, 500
gallons per hour is more than adequate for normal household requirements including
garden and lawns. To pump more water than what you would consider reasonable
requirements usually will involve more costly pumping equipment.
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THE BORE HOLE
Dependant on water requirements, the diameter of the bore should be sufficient to contain
casing, if necessary, and pump with sufficient water space round the pump housing to
ensure a flow of water to cool pump motor and avoid burn outs in submersible pumps.
This applies particularly to small volume domestic bores where in some instances it is
necessary to enclose pump and motor in a "shroud" to increase water flow past the pump.
Experience has shown a 200mm diameter hole with 150mm internal diameter casing, as suitable for most requirements.
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CASING
When drilling through unstable formations (ie) sand, gravel etc., or through saline areas
it is necessary to install casing. The amount of casing will vary dependant upon the extent
of unconsolidated formations as encountered in a great deal of bores in the Hills areas.
It is usually only necessary to case to the commencement of the hard rock. The types
of casing recommended are heavy wall steel and P.V.C. While steel
is a lot stronger than P.V.C. and less liable to be damaged, it is prone to rust in bores with
a very high saline content. In these bores P.V.C. would be recommended.
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MUD DRILLING
This process involves pumping a special "mud" formula to consolidate loose sedimentary
materials whilst drilling. Generally areas where this process is required include Langhorne
Creek and Milang Basins. Drilling in sedimentary areas, as opposed to hard rock formation, the process
of "Well Development" is usually necessary. This involves the cleaning out of the bore to
increase the permeability of the water bearing materials to allow a good flow or yield. This
development is particularly necessary if a sand screen has been installed or the casing
slotted, as the process or development consolidates gravel and sand surrounding the and screen or slotted section of casing.
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 900 cfm x 350 psi Compressor unit with 1800 cfm x 950 psi Booster Unit for drilling deep large diameter holes (one of two units). |
|
|
 Special Bore Service Rig designed for Bore Rehabilitation and Pump Recovery. |
 Heavy duty Rotary Percussion Drilling Rig on 10
x 6 R.F.W. Carrier with onboard 1350 cfm x 500
psi Compressor and quick change angle drilling capacity. |
 Heavy duty Rotary Percussion Drilling Rig on 8 wheel-c|'ive custom built carrier, incorporating on board 900 x 350 Compressor. Deep hole and quick change angle drilling capacity. |
COSTING
Costs and conditions are set out on the "Client Rate Sheet" which the company
issues at the time of site inspection, entirely without obligation. Prior to a site inspection,
research is carried out on general conditions in your area, together with results of
existing bore water yields and depths, to give you an estimate, based on these
findings, of approximate depth and possible water supply.
Drilling rates are based on a cost per metre with a minimum charge of 30 metres.
Should it be found necessary to drill to a depth greater than 150 metres then a
surcharge could apply per metre. This is dependent on prevailing conditions found
at this depth.
Casing requirements are also based on a per metre cost. Extras which are usually necessary include Casing Clamp and Shoe
and Cementing. Occasionally an artesian or overflowing bore is encountered;
Government regulations require all overflowing bores be controlled. This is a
separate "add on" charge and varies from bore to bore.
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CLIENT RATE SHEET
Shown on the right is an example of the 'Client Rate Sheet' . This sets out the various costs (i.e.) drilling rate, which is shown as cost per metre and the same
for casing. It also gives costs of any additional items which could be required and
acts as a check list for you.
These rates are guaranteed for a minimum period of
3 months.
The "Rate Sheet" is usually issued at the time of the site inspection. This site
inspection can be quite a vital part of the drilling process as at this time water
extraction and the drilling process can be discussed.
The Company can advise
you on your water requirements, give details on the Bore Reports and advise on
location. This is a completely free service with no obligations to the client.
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PUMP TESTING
There are many and varied methods of pumping water and types of pumps. The
correct type of equipment is usually determined by carrying out a "pump test"
of the completed bore.
There are two main reasons for the Pump Testing of a bore.
(1) To determine the amount of water (gallons per hour) which can be pumped from
the bore.
(2) To measure the draw down of the bore. The draw down is the drop in water level
that occurs when pumping the bore.
From these two findings the correct type and capacity of pump can be determined
and also the depth at which it must be installed in order to maintain a long term
pumping rate. It is of vital importance that Well Tests be carried out correctly.
Short term tests, that is, up to eight hours are often inadequate. We strongly
recommend 24 hours. There are occasions when it becomes necessary to pump in excess of 24 hours, that situation generally must be decided during testing.
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EQUIPPNG THE BORE
After the bore is drilled the next all important stage is the equipping of the well.
This involves the installation of the correct pumping equipment to ensure the
most economical method of water supply. Illustrated on facing page are some
of the more common pumps in use.
CENTRIFUGAL PUMP
A very commonly used surface installed pump on dams or water tanks but
having restricted use in bores due to its limitations of depth or lift not generally
used at a depth greater than 20-25 feet, operated by electric, diesel or
petrol motor.
JET PUMP
Suitable for small agricultural and domestic use. A simply installed, electrically
driven, self priming pump generally used for shallow depth bores.
CYLINDER PUMP
This is a plunger type pump suspended by a discharge pipe which encloses
the pump rods. Designed for use with windmills and pump jacks. Can also be
diesel or electric powered.
SUBMERSIBLE PUMP
A very popular and efficient unit comprising a combination of vertical turbine
motor close coupled to an electric motor designed for sustained and continuous
operation underwater. The unit is suspended from a surface plate and receives
power from a submersible power cable. One of the most common bore pumps
for all flow rates.
TURBINE PUMP
Generally the most expensive method of equipping bores. The basic element
is a centrifugal impellor followed by a "stator", these two constitute a stage,
dependant of the head required, determines the number of stages making up
the complete turbine. Pump is driven by rotating shaft with motor located at top
of bore, either diesel or electric, and pump at pumping level.
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During the Drilling of the Bore, Salinity Tests are carried out to ascertain the Salinity Level, or Salt Content, of the water supply. The Salinity Chart is shown as a guide to the Salt Tolerances of various fruits, vegetables and grasses.
