Saipan is an island located in the Western Pacific and is part of the Commonwealth of the Northern Mariana Islands. Here, the Commonwealth Utilities Corporation, (CUC) in association with the United States Geological Survey (USGS), has been busy developing a plentiful and sustainable water supply for its inhabitants that meet the Federal Clean Water Act. The goal of the program is to develop a sound water supply that is critical for the well-being of the inhabitants as well as ensuring the vibrancy of the island tourism trade.
For the past 13 years, distributor Western Well Supply has been providing drilling tools, supplies and advice to various companies throughout the Pacific Rim. CUC typically has used tricones over the years to drill water wells, but has encountered performance difficulties when faced with ground conditions consisting of rock and other hard formations.
The CUC consulted the folks at Western Well, who recommended the use of a DTH hammer and bit in order to provide extremely efficient drilling at an affordable cost. The CUC purchased two Numa 10-inch DTH hammers and two 12-inch bits for the tasks at hand. The 10-inch hammers are capable of drilling holes from 97⁄8inches to 12 inches in diameter in vertical and horizontal applications. Designed for long life and fast penetration rates in hard rock conditions, the hammer is designed for completing water wells, rock sockets, caissons, foundation holes, elevator shafts, exploration drilling, blast holes or any other rock drilling project.
The CUC used GEFco Speedstar 25K and 30K drill rigs with on-board 900/350 compressors for the drilling of the water wells throughout the island. The ground condition in much of Saipan consists of formations of clay, limestone and volcanic materials. In addition, difficult high back-pressure conditions are very common in this part of the world. On many occasions in the Pacific Rim, hammers could not drill against the tremendous backpressures that commonly were encountered. With this in mind, the contractors depended on the outstanding service and support Western Well had provided.
In advance of the main project, the Numa hammers were used to drill deep exploratory holes in the central highlands on the island to see if significant water sources existed. Many of these holes were drilled to depths of more than 1,000 feet, which are the deepest ever drilled in the Mariana Islands, including Guam. More importantly, however, the test holes indicated that a significant saturated thickness existed that may prove to be an important new fresh water source for west coast villages that presently receive only two hours of brackish water per day.
The main drilling project required the installation of more than 25 water wells throughout the central highland area of the island. Each hole was 12 inches in diameter, and some extended to a depth of 1,100 feet. In some instances, drilling continued through hundreds of feet of water. This proved to be no challenge for the DTH hammers and bits as they quickly drilled each hole with no incidence of downtime due to product issues. Once complete, the wells produced from 80 gallons to 100 gallons of water per minute - and a constant 24-hour source of clean water.
Saipan Water Well ProjectApplication: deep hole water well drilling
Hole Size: 12 inches
Depth: 1,100 feet
Formation: clay, limestone, volcanic
Hammer: Numa Challenger 100
Rig Type: GEFco Speedstar 25K and 30K