Published articles -


Boreholes - August/September

Why not have your own water supply?

What is the WDA?

The well Drillers Association consists of companies and individuals engaged in well construction, test pumping, maintenance and rehabilitation. It is not open to manufacturers and materials suppliers but a number of our members act as distributors for well-related equipment including pumps. The Association mainly acts as a forum for members to discuss the industry, technical specifications, contract problems, training and the potential impact of legislation on the industry. It also maintains close contacts with the Environment Agency (EA), the British Geological Survey (BGS) and the various Water Authorities and Water Companies.

Does the WDA publish a Specification for water well drilling?

The WDA web site contains Guidance Notes for the Construction of Boreholes for Water Supply which provides guidance for well drillers and clients on what is good practice from contractural arrangements, technical considerations, related specifications and water resources legislation. The Guidance Notes are not currently binding on the WDA members due to the varied nature of site and geological conditions but they are expected to follow them wherever possible.

Can you put me in touch with my local well driller?

The WDA web site contains a list of well drilling organizations who are members with details of addresses, telephone, facsimile and e-mail references as well as contact names. Most WDA members operate nationally so their office address and the distance to your site is not always relevant. As a association the WDA cannot give preference to one Member over another.

How do I draw up a contract and specification for a borehole?

The WDA Guidance Notes for the Construction of Boreholes for Water Supply contains information about what is required in a borehole. Any drilling organization should produce a written estimate fully detailing the construction and expected depth of the borehole, the installation proposed including the method of sealing the borehole against surface contamination and the pump and headworks detail. Any additional work should be detailed and costed in writing during sitework not afterwards.

How big a borehole do I need?

A normal domestic borehole usually has a maximum diameter of 150mm although boreholes with a finished diameter of 100mm or 125mm can be used with certain ground conditions to accommodate a 100mm

How much space is needed for the construction of a borehole?

Except for the most shallow boreholes the minimum working area required is generally 20 metres by 15 metres with access to the borehole location being suitable for a large lorry mounted drilling rig. Wet drilling slurry must either be disposed of on site or taken away ina skip or by tanker.

What about borehole contamination?

The main source of borehole contamination is from leaking septic and fuel tanks and from animals kept close to the borehole location. All borehole installations must be properly sealed below ground level either by grouting or concreting a steel casing into a clay type zone or into rock head or by sealing any UPVC casing or well screen to at least 5 metres below ground level. The WDA Guidance Notes for the Construction of Boreholes for Water Supply provides good general advice on contamination protection, including the recommended methods for manhole construction. The EA also has two related publications called “Water Supply Borehole Construction and Headworks – Guide to Good Practice” and “Groundwater Source Protection Zones.”

Is treatment necessary?

Water must be ‘potable’ ie it must be safe and of drinkable quality. Any new borehole supply should be tested by a local public health laboratory. In many cases the water will require no treatment. However, if there is any evidence of bacterial contamination, an ultraviolet (UV) sterilization unit and prefilter should be installed. This uses UV light to kill the bacteria, and make the water safe and does not taint the water. If the water is turbid – muddy or cloudy with suspended particles – in-line filters can be used to provide good clear water. If the general public is likely to drink water from the supply, it is recommended that UV sterilization unit is installed to demonstrate that all possible steps have been taken to eliminate possible risks.

How do I complain about the workmanship of a WDA member (and non-members)?

Detail the site location, the contractors name and contact number, the nature of the problem. Ask whether the contractor has been advised of the complaint and what was his response. Advise the WDA Secretary of the details and the Secretary or the Chairman will respond.

EDITORIAL

WHY NOT HAVE YOUR OWN WATER SUPPLY ?
With water costs continually escalating and the Environment Agency calling for a water meter in every home and or farm, there has never been a better time to consider having your own private water supply especially in the farming industry.

WHAT DOES A BOREHOLE COST ?
The cost of a borehole is dependent on the geological sequence, the nature of the water bearing stratum or aquifer and the depth to standing water in the borehole. It is also dependent on the yield required and the access to the borehole location. Some boreholes require a well screen and a gravel pack to restrict the amount of fine materials pumped through the borehole. It is recommended that you approach drilling contractors that are members of the WDA (Well Drillers Association) initially for a guide price and to discuss particular requirements that you have and then request a written estimate. Remember to include the cost of the pump, rising main, electrics and discharge in any estimate.

WHAT YOU SHOULD GET. The illustration (left, click to enlarge) shows the detail of a typical water well construction complete with installed submersible pump. The illustration does not show the completed headworks, this is to be discussed with the contractor.

DO YOU NEED A LICENCE ?
In England and Wales, under the Water Act 2003 any borehole or well yielding less than 20 cu. metres per day (4,400 gallons per day) does not currently require a consent to drill and test pump or to extract water up to that limit. For intended yields in excess of 20 cu. metres per day then a Clause 32 Consent is required from the local Environment Agency to drill and test pump any borehole and an extraction licence is required to pump the borehole after the test pumping is completed.
At this stage it is worth noting that you may also require planning permission from your local council, please make sure that you or your drilling contractor ask the question from the relevant council, this should not incur any costs.

IS THE QUANTITY OR QUALITY OF THE WATER GUARANTEED ?
The key element to minimize the risk is to obtain as much information as possible prior to committing to a drilling programme, hence the recommendation that a borehole prognosis be obtained. Whilst this is not a guarantee of success, it can highlight risk at an early stage. There will always be an element of risk that no water will be found, and this needs to be fully understood by all parties.
A hydrogeological report can be obtained by your drilling contractor or by contacting the BGS direct, (British Geological Survey) who are based in Wallingford, Oxfordshire and can be reached by phoning 01491-692299 or 01491-692394. Current cost of a report is about £350.00.

FURTHER INFORMATION Please contact direct the Secretary of the WDA – Mr. David Duke on 07736364259, alternatively visit the WDA web site – www.welldrillers.org or e-mail David on david.s.duke@gmail.com