Boreholes could be the answer to saving money

A typical 160 cow herd with 80 youngstock needs about 24cu m of water a day, says DairyCo extension officer Chris Coxon. “The logical first step is to contact the EA to check the viability of your plan, although there is no obligation to go through the EA when you plan to keep abstraction below 20cu m a day,” explains Mr Coxon.

“The EA will look at what else is going on in the area in terms of water supply, use and abstraction. When you get the go ahead from that, then the next step is a water prognosis report which will provide information on the geology of the area and can be interpreted to predict the likelihood of finding water.”

Surveys or site reports are usually obtained through drilling companies or a water consultant and cost from £65 to several hundred pounds, depending on the level of detail and interpretation. This usually includes a percentage figure of finding water at given depths and an estimate of volume. However, there are no guarantees on the quality and volume of water, or on the sustainability of either of these, so drilling will always carry a risk.

In some areas it is not practical to abstract groundwater, for example on parts of the Somerset Levels with high saline content. But provided the prognosis report is positive, the next step is to select drilling contractors for tenders.

Consultants caution there are many stories of poor service, so use a contractor with a good track record, preferably recommended by other customers. Previous and future land use must also be taken into consideration when siting the borehole. Potential contamination from past and future activities, for example septic tanks and slurry stores, is frequently a problem and any likely expansion of buildings should also be accounted for.

Cost

The prognosis, a site report, pipework and drilling usually costs between £4000 and £6000 but in some situations costs can be lower than this, says Matthew Renshaw of Jackson Drilling, Baltonsborough, Somerset. Electrics, pipe run to the dairy, pumps, storage tanks and any specialist treatment such as filtering would be in addition to these figures, taking the range of fully installed systems to between £10,000 and £20,000, says Mr Coxon.

The large range in price is also accounted for by variations in drilling depths and soil types. As a guide, Mr Renshaw reckons drilling costs are roughly £60/m with an additional £20/m to line the drilled hole. Most boreholes are drilled to between 30m and 40m but 100m is not uncommon.

It’s also important to keep the flexibility of a mains supply, even when only used in an emergency, adds Mr Coxon. However, water used in dairy plant and equipment must be of high potable (drinking) quality, so mains water is recommended here for peace of mind and safety.

Getting permission

When you intend to abstract more than 20cu m a day, as well as requiring an abstraction licence, you first need to seek permission from the EA to drill and test the borehole, says Keith Seymour, from the Environment Agency.

“The purpose of this is to ensure the proposed abstraction does not affect other water users or groundwater dependant rivers or wetland. Also, there are some catchments where groundwater is fully committed. Therefore, it’s worth coming to the Environment Agency at an early stage to check.

The Environment Agency will do an initial risk screening to help identify any obvious problems and will ask the farmer to carry out a water features survey, looking at neighbouring boreholes, springs and rivers. They will then report what degree of testing is needed to support any licence application, and may specify certain conditions on borehole construction.

“For example we may set a maximum depth of drilling or ask the farmer to seal off the upper part of the borehole to prevent interconnection of different layers of water bearing strata, or aquifers,” says Mr Seymour.

The output or yield from the borehole will not be known until the borehole has been properly tested, nor will its quality. “Just because a neighbour has a reliable supply does not mean that you will,” warns Mr Seymour.

“Whether or not our permission is needed, it is always in the owner’s interest to ensure the right depth and type of casing is installed and sealed to avoid pollution of their own supply and to keep the borehole stable.” This will depend on local ground conditions, which is where the geological prognosis helps the contractor to design and construct the borehole properly.

The headworks of the borehole should also be sited either in a sealed chamber or above ground to prevent pollution. “Owners are often not aware of this good practice, although a reputable, specialist contractor should be,” says Mr Seymour.

The cost of an annual licence depends on the volume of water authorised to be abstracted. There is also a first time application fee of £135 and in some cases a £100 advertising charge. There is no fee for the Groundwater Investigation Consent.

The quality of the water should also be analysed to make sure it is fit for use, although this is outside the remit of the Environment Agency. It is a legal requirement drilling records of all water supply boreholes deeper than 15m are sent to the British Geological Survey.

CASE STUDY – GELLI AUR COLLEGE, CARMARTHENSHIRE

Installing a borehole at Gelli Aur College, Carmarthenshire, was part of an ongoing dairy development for two herds totalling 500 cows and has the potential to save £8000-£9000 a year in water costs.

When looking to site the borehole, a ground survey eliminated some areas where contamination from earlier uses such as workshops and housing could have caused problems for water quality. So the borehole was sited further from the dairy unit than originally hoped, adding to the costs, says farm manger John Owen.

Finding enough water was never going to be a problem, as the farm is on a flood plain. “You can dig with a spade and find water,” says Mr Owen. However, tests revealed high levels of manganese which have to be filtered out before the water is suitable for cattle. Hypochlorite is added to the water before the filtering process.

Installing the borehole and supplying the dairy from it has cost about £10,000, with the filtration equipment adding considerably to the original estimates. The annual abstraction licence costs £152.

Mr Owen says the savings from installing a borehole are worthwhile, but warns those considering it should be prepared for problems. For example, at Gelli Aur the original pump has already had to be replaced with a higher capacity model. Savings are being limited by the need for filtration which slows up supply. So the savings being achieved at present are only half what they might be when the tanks could be filled quickly enough to cope with peak demand.

The unit relies on mains water as well as its private supply and some remedial work had to be done post installation to remove the possibility of borehole water getting into the mains supply.

“Annual servicing costs at Gelli Aur are £500 but to date we have spent £1500 annually on maintenance,” says Mr Owen. “Ongoing costs should be assessed in advance where possible. For example, consider who will service and repair any equipment, are they local, are they reliable, what is their callout fee and how long will they take to get to you,” he says.

He also suggests getting several prices and to make sure contractors are quoting on a comparable basis. “This is because some companies are only quoting for the drilling and installation of the water supply to the borehole pump and not the electrics, storage tanks and costs for running a supply, which all may be extra.”

“Make sure your installer knows what is required by the Environment Agency in terms of keeping the private supply isolated from the mains supply. There must be no possibility of contamination,” advises Mr Owen.