Bored Water Wells – Part 2
by Greg Ettling
July 1, 2008
Illinois driller deals with – and flourishes in – varying geologies
In
the first part of this article, Andy Wiesenhofer of Reynolds Drilling Corp.,
Riverton, Ill., told us about his firm’s entry into the bored water well
market, and how the use of fiberglass pipe in those applications has evolved.
Here, in part two, we’ll look at a little company history and some of the
specifics of Reynolds’ work.
Reynolds Drilling usually has 20 employees, depending on the workload, and the
firm’s drilling projects are about evenly split between well drilling and pump
repair and test drilling.
Wiesenhofer started out cable-tool drilling in 1976 for his dad, who still has
a drilling business in Washburn, Ill. “In the early 1980s, the bottom kind of
fell out, and I left to pursue some other interests. I worked for some
consulting engineers, and that’s where I got into the test drilling with auger
rigs and split-spoons for geotechnical projects. And then the environmental
market started to come on a little bit. Then, in 1988, I went back to drilling
cable-tool until the mid-1990s, when I went to Springfield to work for AE
Exploration doing environmental and geotechnical drilling again. In the late
1990s, we got a bucket rig to do methane wells in landfills, and that’s what
got us started on the bored wells.”
As detailed in the previous article, Wiesenhofer went through no small effort
to make fiberglass pipe an integral part of his company’s bored well projects.
That’s what works best for Reynolds, and that will continue to be its standard
procedure.
On Occasion …
There are exceptions, however. “We also use some PVC – 16-inch, large-diameter
– in some bored well applications,” Wiesenhofer explains. “Last year, we did
three 16-inch jobs out of 140 total projects, so that’s a pretty small
percentage.”
If he runs into a fine-sand situation, he tells us, “With our fiberglass pipe,
we slot it in the field, and we can get about a 50-slot screen. We use buckshot
gravel around the outside of it for the gravel pack. Sometimes, if we have a
sand-pumping problem, we’ll line that 30-inch pipe with a 6-inch pipe and
screen, and use a finer filter pack to make kind of a double filter pack. Last
year, we only ended up with about four jobs that we needed to do the 6-inch
liner on.
“Of those 140 jobs, we flood-drilled 60 of them. On 24 of them, we did rock
drilling where we cut into the shale and sandstone, and made wells in the
bedrock. It’s kind of hard to do with the bucket rigs in limestone or cap rock.
We will core that with core buckets. Of our three bucket rigs, two of them have
hydraulic pulldowns on them, and that’s where you actually can put the weight
of the rig on the drill string; the other one is a straight kelly rig. We
bought a new bucket rig last year that has 120-foot kellys, and now we can do
down to about 115 feet without having to put on any extension bars. Our
fiberglass pipe is OK’d to 120 feet of depth.
“In some areas, you can do drilled wells in sand and gravel just fine, but in
other places, if you drill down into the bedrock, you’ll get saltwater. A bored
well in the shallower part gives you fresh water still. According to state
code, we are able to use water after 10 feet; anything above that we’re not
supposed to use.”
Typical Installation
For Reynolds’ wells, Wiesenhofer explains, “We typically start off at the top
with a 43-inch hole, and then down about 15 feet, we’ll drop down to about a
36-inch hole. And then we take that down to the depth we want and set the pipe.
That allows for about 3 inches of gravel pack all the way around. From 10 feet
down, there is a transition from that big pipe to a 6-inch pipe that comes up
to about a foot above grade. The gravel pack goes to the top of that lid, and
then there’s a 1-foot bentonite layer that goes in on top of that – in the
11-foot to 14-foot region. Then that’s backfilled with clay. This makes the
transition to the smaller-diameter pipe easier to facilitate the installation
of a pitless adapter. That bentonite layer has to be in there to keep out
surface water. That was one of the improvements in the code; in the past, there
wasn’t any provision to seal that off.
“We’ll get calls about old bored wells that experience problems after it rains,
and we’ll dig them up around the outside – down to the lid – and put in a
bentonite layer, and that usually solves the problem.”
Asked about well decommissioning, Wiesenhofer relates, “Those wells have to be
filled with either all bentonite or a bentonite-cement grout. But because of
the diameter, a lot of times, we’ll just dig down to the top of the lid and
backfill with clay. If the lid is very deep and it can’t be reached with a
backhoe, we’ll fill the larger part of it with pea gravel, and then a foot
below the lid, to a couple of feet below the surface, that has to be filled
with bentonite. It’s better to actually take off the lid and backfill it with
clay, but that’s not always possible. Some of the older concrete wells came all
the way to the top of the ground, actually above grade, and that still is a
provision in the code that they can be done like that, but they have to have
concrete poured around the outside from 10 foot down to grade.” He also notes
that the casing must be removed to 2 feet below grade for proper abandonment.
Long-term Plans
“We’re going to continue to do what we do,” Wiesenhofer states confidently. “We
have a pretty good corner on the market.” An important key to that position, he
says, is the utilization of fiberglass pipe. “That has made it easier to travel
more efficiently because of the decrease in weight compared to the concrete.
Before, if we were working 100 miles away, we’d have to shuttle tiles back and
forth; one 3-foot tile weighs about 1,000 pounds. The fiberglass pipe weighs a
lot less, so we can head out with up to 200 feet of pipe on one trailer. The
fiberglass has been a big improvement to the installation of bored wells; I’d
never go back.” ND
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