A GOOD START
Borehole design, drilling and development is a complex operation.
If you are considering installing a borehole and you would like the experience to be as streamlined and successful as possible then there are some key pointers to be aware of so that you can reduce what can be a frustating, time consuming and expensive affair.
Our recommendations are inline with SANS (South African National Standards) and BWA (Borehole Water Association)
How to get ahead...
PROS
-
Huge savings on your water bill
-
Provides water security for your family
-
Water independence
-
An investment
CONS
-
A messy process whereby your garden will need a period to renew.
-
No guarantee of finding water (although we have a 100% success rate)
TIPS FOR A SUCCESSFUL BOREHOLE EXPERIENCE
TYPES OF BOREHOLE
There are three main types of borehole drill terrains found in and around Cape Town, in brief, they are:
MUD
Mud Rotary drilling is a versatile and dependable technique ideal for drilling into soft rocks, sand and clay layers.
The process uses rotating hollow drill pipes which carry down drilling muds to lubricate, cool and clean the drill bit whilst drilling the hole.
The Mud Rotary technique also coats the side of the borehole with a thin layer of clay from the drilling fluids which stabilises the wall of the borehole.
Once water has been located, the water is flushed clean and the walls of the borehole are stabilised with PVC casings.
In Cape Town, most areas are a combination of mud and rock drilling.
ROCK
Rock Percussion drilling is used on hard rock layers and uses compressed air to drive a pneumatic hammer into the rock.
Our rigs are combination rotary-percussion drilling, The combined hammering and rotation of the bit results in the relatively speedy penetration of hard rock.
Once you have drilled through rock it is a solid hole which nothing can collapse into.
In Cape Town, most areas are a combination of mud and rock drilling.
BOULDERS
In areas, like Somerset West, the underlying rock structure consists of large boulders which can collapse into the hole whist drilling.
ODEX drilling is a specialised drilling technique in which steel casings are attached to the hammer part of the drill and protect the drill and drilling process from dislodged boulders. The steel casings are left in the ground to maintain the structure of the hole.
This method, like rock drilling, uses an air compressor which drives a pneumatic hammer through the rock.
BOREHOLE LOCATION
The location of your borehole is mainly determined by the borehole's purpose and requires desk study, site assessments, and surveys to assess the following considerations:
Output What will it be used for? - Is it for drinking water, household use, irrigation or other water related functions?
Access Is there accessibility for the drilling team and equipment?
Location Is the proximity of the borehole location appropriate for its use?
Yield Will there be sufficient yield and appropriate water quality for the intended purpose?
Quality Have potential sources of water contamination been evaluated in the assessment?
Forms Has the required borehole application form been submitted to the municipality 14 days prior to abstraction?
BOREHOLE DESIGN
Borehole design is important and necessary. A well designed borehole with a professional install should result in a cost effective, reliable, robust method of obtaining water for the future.
Further, a well designed borehole can protect the natural groundwater from becoming contaminated. Sadly, borehole design and development is one of the most overlooked aspects within the industry and not enough time, care or attention is put into this vital stage of the process.
Current climate models predict that South Africa is to become hotter and drier and the long-term supply and quality of our groundwater should be considered carefully during this stage.
DESIGN OBJECTIVES
Optimisation Ensure the borehole has the best opportunity to be fit for purpose e.g. highest yield with minimum drawdown
Quality Best quality water possible for the installation
Fresh Free from salt water intrusion near coastal areas
Filtered Sand-free water
Protected Appropriate protection from contamination
BOREHOLE CONSTRUCTION
-
Two 1.5 m mud pits are dug
-
The first is to capture the cuttings that surface during the drilling process
-
The second mud pit is to recirculate the now cleaner water back into the hole which assists the boring process
-
Drilling commences to the desired depth
-
Once we have water we drop our PVC casings down (unless it is a rock/boulder drill where the process differs)
-
Construct appropriate formation of casings, screens, gravel and chipstone backfill which help filter the water
BOREHOLE DEVELOPMENT
Once you have a water supply our drillers will:
-
Thoroughly flush the hole of all loose debris
-
Insert the pump and let it run for 24 hours to remove any contaminants
-
Assess the current water yield and improve if necessary
-
Ensure the formation of the casings, screens and gravel allow for easy passage of the water into the borehole
-
Ensure the borehole is fit for purpose e.g. yield, diameter, depth, casing and screen, gravel pack/formation etc.
POST BOREHOLE
-
The hole is secured with a cap
-
Electrical cables and the controls for the pump are run and tested
-
The site is cleaned