In modern times, drilling for water has left behind the ancient art of dowsing and now employs a host of scientific tools, testing and advanced machines, all aimed at taking the guesswork out of locating large sources of water deep in the earth.

Marlborough has long pursued a plan to obtain a consistent supply of water, independent of neighboring Newburgh. Last week Marlborough got lucky.

After a first drilling attempt failed, a second try proved the charm and has brought Marlborough a step closer to realizing their goal of establishing four or five wells to supply water to the town on a consistent basis.

At the suggestion of the town’s geologic consultant, HydroSource, the second drill site was moved just 30 feet to the west of the previous attempt on the St. Andrews property in the Marlborough hills. It appears this small distance made all the difference because a steady and strong supply of water was realized at several depths along the 700 feet that was drilled into the earth.

Ricky Tompkins, of David H. Tompkins & Sons of Montgomery, said at the 620-foot mark he was pumping approximately 60 gallons a minute out of a 6-inch hole. He said this was triple the production of the previous unsuccessful well and is hopeful, after later testing, that this well will come in at a yield of at least 100 gallons per minute. He said if it finalizes at 150 to 200 gallons per minute, “that would be awesome.”

Tompkins said for this job he used a 6-inch carbide steel tipped drill bit that was strung with a rotary [pneumatic] hammer and charged with 1070 CFM, 350 psi [pounds per square inch] rotary screw compressor. He said diamond tips are used for drilling in oil fields, in part because they last longer, but the cost differential is quite substantial; $7,000 compared to carbide ones at $500 per bit. Tompkins used 35, 20-foot lengths of pipe for the 700-foot well.

Tompkins said at the lower depths they found multiple shale rock but some with white quartzite seams, which is evidence of a potentially good supply of water. He said for the first 200 feet he was able to drill six feet per minute, but at the lower depths the process slowed to about two feet per minute.

“The rock is exactly the same [but] there is so much water on top,” he said. “We have to concentrate on lifting the water and drill at the same time, so it takes a lot more air. The air that charges and lubricates my hammer also blows the cuttings out to make a clean boring hole.”

At 700 feet, Supervisor Stephen Osborn called it quits, suspecting that this one well will be a good source of water.

“With the rig in, if you’re getting 65 gallons a minute, it is likely to mean that without the rig you’re getting 90 to 100 gallons per minute,” Osborn said. “That’s good because that’s sort of the range we’re looking for. This well alone can supply a quarter of the town’s needs, as is.”

Osborn said he decided to go deeper than originally planned “because we’re seeing that mix of rock that tells us we’re in the right spot,” adding that the cost for this well will be near $20,000.

Porter Moore, of HydroSource, took filtered samples of the water every five feet, placing the small particles and flakes of stone in sealed marked baggies to create a geologic record. At about 690 feet he showed Osborn a mix of black and white specks, a clear indication that the drilling had hit quartzite.

“There are two different rock types coming together, so this is a very good sign.” Moore said. “We go into that contact because that’s generally where the water will be.”

Moore calls himself the company’s “go-to guy”
“I do a little bit of everything – geophysics, pump testing, drilling and I’m always on site,” he said.

Moore said additional study of the area indicated that if they moved over by 30 feet they would hit the points of contact needed to unleash the type of water they were seeking. He said the first 200 feet showed signs that “we were stepping into some zones that looked favorable.”

He said the “signs” were small pieces of white quartzite “that are veins that run through the shale that indicate there are some different rock types connecting.”

Moore said some larger pieces of stone also came to the surface, which indicates there already is a fracture in the rock below.
“When we’re drilling into that, its hammering away at it and bringing those larger chunks up so we’re going through a fracture zone at that point,” he said.

Moore said it is ideal for the drill to split two pieces of rock that have come together, which will allow access to the most amount of water.

“When you do, filtration of the water will come into those zones [and] you’ll be hitting into pockets of water,” he said. “The fractures will be funneling water into those areas and that’s what we’re looking for.”

Moore said he will return later with a crew to perform a 48-hour continuous pump test that will accurately gauge the gallons per minute the new well is producing. The testing will also reveal how far the water may be drawn down as it is run continuously.

Eventually, a full battery of water chemistry tests will be done, checking for any contaminants and iron oxides. Samples will be taken every hour. Wells in the surrounding area will also be closely monitored to see that they are not being drawn down as water is pulled from this new well. If neighboring wells are adversely affected, the Town Board may have to re-evaluate whether to put this new well into full operation.

By MARK REYNOLDS
mreynolds@tcnewspapers.com