February 2011, Vol. 66 No. 2


Proposed HDD To Advance Water System On Hawaiian Islands

The Kauai Board of Water Supply has issued a Request for Proposals for a water development project that uses groundbreaking advances in the art of horizontal directional drilling (HDD), while building on existing water development technology in the Hawaiian Islands.

The board proposes a two-mile-long, high-elevation horizontal shaft capable of producing up to 8 million gallons per day artesian flow that could approach 1,200 psi while drilling up to nearly 12,000 feet. In this project, global and local environmental factors play a role, as do cultural, economic and technological issues.

One benefit of this project is that water can be gravity fed to customers rather than pumped at a high electrical cost. Another is that as the water flows to customers can be fed through hydroelectric plants, actually producing electricity instead of expending it.

Getting water from high-level sources in the Islands is certainly not new. High-level tunnel water sources have been in existence for a century in Hawaii, with examples on Oahu, Maui and Lanai. Each of those tunnels was hand-dug, and work was stopped when sufficient pressure was encountered, to avoid danger to the workers. Several continue to produce potable water today.

The majority of Kauai’s water is drawn from groundwater supplies floating on top of ocean water. Depending how high above sea level people live, the water must be pumped upwards. On an island with some of the highest electric costs in the nation, that pumping is exceedingly expensive. Due to both scarcity and the cost of production, some have suggested that water is rapidly becoming the new oil. The proposed directional drilled well is expected to reduce power costs as well as generate power as the water is supplied to lower elevation consumers.

“This horizontal shaft will directly benefit the customers in the central Kauai area, which is our largest customer base,” said Project Manager Dustin Moises. “Customers will likely enjoy uninterrupted service during natural disasters and power outages, while minimizing the departments’ reliance on imported fossil fuels. In the long run, water will be available at lower rates to all of our customers throughout the island, not just central Kauai, due to the energy savings from the horizontal well.”

“In the process of meeting this goal, the department and I will work with the community addressing all of the local, environmental and cultural factors as well as any eco-tourism concerns,” said Moises.

The proposed directional drilled well would draw the same water now being tapped for the island’s domestic and agricultural water use, but would intercept it at a higher elevation. Construction of the shaft will require advances in the art of horizontal directional drilling. The safety of workers is just one of the issues. Work will require exceptional care, since it will occur in the sensitive physical and cultural environment of the Kahili Mountain range.

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