Sinking a fence post or planting a shrub often pits Islanders against layers of clay that can make such relatively simple tasks frustrating. Moreover, many parts of the Island are so stricken with hardpan that pickaxes don’t bite the earth, they ricochet off it. With that in mind, imagine having to regularly dig down through Vineyard strata not three feet or so, but, say, to a minimum of 20 feet? Nearly impossible by hand and no mean feat even for a piece of excavation equipment like a backhoe. But for Island Water Source’s drilling rig, cutting through 20 feet of Island is merely a geologic appetizer.
Encountered on the road with its mast down and its drill rods packed in their carousel, the rig looks more like a piece of mobile artillery than a truck hefting drilling machinery. But seen on site braced by its four outriggers, its mast aloft, and a great column of rods whirring into the earth, its true purpose is clear. Mounted on an International Harvester (now Navistar Harvester) 4400 twin rear axle truck, the rig was made by Iowa drilling manufacturer Gus Pech and can be fitted out to both drill and auger into the earth. On average, the rig bores down to a depth of about 100 feet in order to tap potable water on Martha’s Vineyard. In some of the more elevated areas on the Island, it can cut a shaft much deeper. “We have drilled seven wells on this Island that approach or exceed 400 feet,” said John Clarke, the company’s owner.
The tremendous torque the rig generates enables roller bit technology that was pioneered by Howard Hughes Sr. during the days of early 20th century oil extraction, meaning it can carve its way down through the worst stone and clay of the Island. Improved upon by his tycoon son, Howard Hughes, as well as several subsequent people and firms, the tricone rock bit is an industry standard. Affixed to the end of a length of Island Water Source drill rods, it will buzz through boulders with relative ease. In fact, only fine sand takes a real a toll on this type of bit, by dulling it prematurely. A new rock bit has approximately 12,000 to 15,000 feet of drilling life to it.
Water happens to be the key to drilling for water. This is why Island Water Source fields a separate truck — another International — customized with a low-profile 1,500 gallon tank to work in tandem with the drilling rig. A portable centrifugal pump sends water from the tank truck to the rig. Aside from reducing friction, water is “used for mixing drilling mud, backwashing the mud out of the hole and for developing the well to remove fine materials from the well screen and increase yield,” said Dave Schwoch, Island Water Source’s longtime driller. The mud, a viscous soup of bentonite (a type of clay commonly used in cat litter) and occasionally polymers, is mixed to different consistencies, depending on the strata being drilled through, in the rig’s mud tub. Then it’s fed into the expanding borehole where its weight and density creates hydrostatic pressure that helps keep sides of the borehole from falling apart before a well casing can be inserted.
In places on the Vineyard where the ground isn’t especially tough and the water isn’t especially deep (80 feet or less), the drill rig can be reconfigured with spiral auger stems as opposed to the pipe-like drill stems. The auger stems look somewhat similar to the post-digging attachments sometimes seen on the rear of Island tractors, albeit much longer.
“This method is often used in the outwash plains in areas we know do not consist of heavy clays or large rocks,” Mr. Clarke said.
“I may auger 25 percent of the wells in a given year,” Mr. Schwoch said.
Whether employing drill or auger, the rig sees a good deal of its action up Island, where there is no municipal water. Despite its public water system, Edgartown’s municipal water isn’t connected to all its taxpayers, so the rig is used to drill quite a few wells in Edgartown, including Chappaquiddick, where its size and weight (more than 20 tons) gives the Chappy ferry a decent stress test. Of the other two down-Island towns, the rig sees action in roughly 10 percent of Tisbury and virtually zero in Oak Bluffs, according to Mr. Clarke.
“Being made up of unconsolidated glacial till [the Island is] not your typical cookie-cutter drilling environment,” Mr. Clarke said. He is appreciative of the Gus Pech rig’s ability to consistently deliver in tough and varied ground.
With 26 years of experience and over 2,300 wells under his belt, Mr. Schwoch continues to test that consistency, drilling through whatever the Island can muster. “Sometimes I run into plant matter or trees down over 300 feet and I have hit layers of shells down 180 to 200 feet, near the shore in Edgartown a few times,” he said.
For more information about Island Water Source and their rig visit their Facebook page: facebook.com/pages/Island-Water-Source-Inc/162447697136360.