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Nevis – In The Business Of Building Nevis

The question has been asked before: With so much water underneath, why did Nevisians have to struggle to have it flowing steadily in the taps at the home? With a demand of 1.3 million gallons of water per day, there were times when Nevisians would be advised to sparingly use the little water available.

Fresh water brought to Nevis

Fresh water brought to Nevis

That was happening right here in Nevis a mere two and a half years ago. The island had an erratic water supply. Sometimes, no water at all.

Today all that is changed and Nevisians have more water being pumped from the ground than they actually need. An additional 1.5 million gallons per day to be exact. In economics one would say that the supply is higher than demand. That always leads to better and cheaper availability of commodities. Nevisians are now not only enjoying more water but also enjoying better quality water than any other time in history.

ACTION! spoke to Dr Roland ‘Skip’ Hoag, the person behind the company that has made this difference on the island of Nevis — Bedrock Exploration & Development Technologies (BEAD).

“This project began two years ago with a goal to develop a million gallons per day of new ground water for the island of Nevis,” commented Dr Hoag. “The exploration programme used is systematic and includes existing geologic data, well data, satellite imagery and digital elevation data to map the geology and the geomorphology of the Earth’s surface.”

He noted that the data is combined in a computerised Geographic Information System (GIS) and once the initial “remote” mapping is done detailed geological mapping is conducted in the field in order to “ground truth” the newly integrated

The combined data is evaluated and areas that they think might be favourable for ground water are mapped. A geophysical programme is then designed to verify the geological model of each of these favourable zones and to pin point sites for test drilling.

The next step is where a series of transects across the favourable zones are laid out and subsurface data is collected every 20 metres or so along those transects. The geophysical data will image the subsurface geology to a depth of over 1000 feet. This imaging allows for the delineation of buried channels and lava flows which will likely be saturated with water and are recharged from the mountain.

“These channels and lava flows were covered over by the last eruption which occurred about 100,000 years ago, burying them so that their presence is not obvious on the surface and therefore had been missed by prior drilling attempts on the island of Nevis,” reported Dr Hoag.

The geophysical surveys done on Nevis resulted in the pinpointing of the most favourable drill targets. In addition to the geophysical surveys done for the water project BEAD used the same technique to map favourable structures for the geothermal exploration effort. By combining the two efforts each project benefited because they were able to do more surveying giving a much more comprehensive view of the earth.

According to Dr Hoag, the results of the geophysical surveys were tested by drilling test wells

According to Dr Hoag, the results of the geophysical surveys were tested by drilling test wells. The initial drilling allowed them to calibrate the geophysical surveys thereby identifying the targets that would be the most favourable for
the development of high yield wells. Initially several test wells were drilled on the western part of the island because that is the area with the greatest need for water.

“Even though the geophysical targets were small we needed to test several of them in order to rule out the western side of the island for further exploration,” said the water engineer. “The most successful well was located in Barnes Ghaut but the flow rate was not high enough to justify the expense of putting it on line.”

Due to the disappointing results the geophysicalsurveying expanded to the western side of the island and very favourable targets were identified in the Hog Valley, Hicks Estate, Maddens, Fothergills, Gingerland and Hamilton Estates areas. Very successful wells with excellent water quality were drilled in the Maddens, Fothergills and Hamilton Estate areas. The wells at Maddens and Fothergills produce over one million gallons per day. Since the island’s average daily water demand is only about 1.3 million gallons per day these wells have allowed for the replacement of poorer quality wells resulting in a significant improvement in island wide water quality.

He explained that the reason the water quality is high is because the wells are located at higher elevations closer to the main source of groundwater recharge, Nevis Peak. Noted Dr Hoag: “Therefore the wells are getting water that is more actively recharged from the volcano. On the other hand the existing wells near the coast have increased dissolved mineral content due to a longer flow path from Nevis Peak and from salt spray from the ocean.”

In December 2008, BEAD were awarded another contract to develop an additional half a million gallons per day in an area west of Hamilton Estate. This as a result led, in February, to the drilling of a well there, which has yet to be tested, but it was expected that it might do as much as a half a million gallons per day.

He confirmed that the quality of the water is excellent. However, its temperature is a little warmer than the Maddens and Fothergills wells, but cooler than the water department’s wells in Charlestown. This well will be tested and equipped in April and May.

“We have other proposals in front of the government to drill, test and cap wells at three other sites which will allow the government to conduct forward planning since they will know the exact locations for their future water supply,” the water engineer pointed out. “So, that is really where we stand in terms of what we have done and what we hope to do in the future.”

Before BEAD water contracted to look for new ground water, Nevis had about 1.2 million gallons per day, but a number of the wells have fairly poor quality water which leads to a lot of complaints. According to Dr Hoag, these wells will be permanently shut down, but on the other hand some of the other wells in Maddens and Zion will continue to be used during a peak times when the demand increases to a million and a half or even two million gallons per day, resulting in no shortage during the year.

“Peak demand can be up to one and a half times the average daily demands,” observed Dr Hoag. “So if the average demand is one million gallons a day peak could as much as a million and a half last for a month or more in the dry season. That is why the island needs additional water beyond their existing supply.”

He further observed that while the island has quite a few storage reservoirs there is not nearly enough to store water for extended periods of time. As demand goes up with continued growth the existing wells can be used to meet part of this increased demand. It is a very good Nevis water – testing taste buds situation, he noted.

Exploring for and drilling production wells.

According to Dr Hoag, the results of the geophysical surveys were tested by drilling test wells

“In addition to exploring for and drilling production wells, our project required us to install the pipeline from the wells to their existing storage tanks or transmission mains,” added Dr Hoag. “Therefore the location of the production wells had to be reasonably close to the existing facilities. Consequently the exploration programme was somewhat focussed in the vicinity of these facilities.”

He commented that since the storage tank in Maddens is 1,400 feet away from the well a significant amount of pipe had to be laid. Fothergill’s required less pipe (500 feet or so) but the Hamilton tank well will require 1400 feet also.

According to Dr Hoag, the conventional pipe used here for waterline is PVC which is good but it is somewhat brittle and the joints can leak. BEAD decided to use polyethylene pipe with joints that are fused (melted) with a fusing machine. This pipe is more flexible and thicker, so it is less likely to break. It is more complicated to install but it should be leak free for a long period of time.

“Another new technology that we are using on these wells are variable speed drives that allow the pump rotation to be altered which will either decrease or increase the pumping rate,” observed Dr Hoag. “So as the storage tank fills up the flow rate from the well will go down and as it empties the flow rate will increase. The variable speed drive only uses the amount of current necessary to pump the water. With a conventional pumping system the wells are either gated with a valve or the wells are constantly being turned on and off, therefore using a lot more energy.”

He pointed out that they have also equipped each of the pump houses with a metrological station which measures rainfall, wind speed and several other metrological parameters. In addition the well yield, water level and several electrical parameters are measured. This data is transmitted through the internet and can be downloaded any where in the world. In fact the well can be turned on and off remotely if required.

This technology has been developing over the last twenty years and in the last five to six years the technology has reached a level where it allows them to minimise the human need to go out to the well and make measurements, although we do that as a backup.

Each of the pump houses is equipped with a diesel backup generator with a storage tank with 7 days of fuel. The generator will automatically turn on should the power be off for an extended period of time. Consequently if there is a hurricane and there is no power for an extended period of time water will be delivered into the island’s distribution system.

A PRODUCT TO BE PROUD OF: During this year’s Agriculture Open Day held at the Villa in Charlestown March 26-27, BEAD in collaboration with the Nevis Water Department set up a booth, where one of the attractions was water tasting. The tasting competition was conducted by Jerome Pinney, a pump technician with the Nevis Water Department. Three bottles with crystal clear water were on display and patrons were challenged to taste from the each of the bottles and point out which had water from Nevis wells. Pictures show Vanessa Parris of Hamilton tasting. She picked the correct one and won a phone card from one of the mobile providers.