I
magine pulling your drilling rig up
in downtown Manhattan, parking on
the sidewalk, and setting up your
site.
It’s actually happening more and more
frequently.
As the use of geothermal energy for
heating and cooling grows more popular, even buildings in urban centers such
as New York and Boston are replacing
their outdated HVAC systems with geothermal heat pumps.
Nationally, ground-source heat
pumps are not new. But the use of geothermal heat pumps in the New York
City metropolitan area is relatively
young, with the first systems used for
both heating and cooling placed into
service in the last 15 years, says John
Rhyner, LEED AP, senior project manager with P.W. Grosser Consulting in
Bohemia, New York. Founded in 1990,
P.W. Grosser specializes in evaluating a
geothermal system’s “ground coupling”
options, system design, and conducting
due diligence of subsurface conditions.
One geothermal design that is growing in popularity is the standing column
well, essentially a recirculating water
well constructed as a free-standing rock
borehole.
Standing column wells have grown
in popularity because they provide “the
biggest bang for the geothermal buck,”
explains Rhyner. These wells can
deliver from 20 to 40-plus tons of heating/cooling capacity per well (1 ton
Photo courtesy of DRAGIN Geothermal Well Drilling
GEOTHERMAL/continues on page 28
Standing column wells, a relatively new technology,
are gaining acceptance in the northeastern United States
and presenting a new opportunity for water well drilling
firms at the same time.
By Jill Ross
NGWA.org
Jill Ross is a former editor of
Water Well Journal and worked
for the National Ground Water
Association from 1996 to 2004.
Today, she does freelance work
from home. She can be reached
at [email protected].
Water Well Journal December 2010 27/
Table 1. Example number of wells and loops and land area required for a
100-ton system.
Geothermal
System
Closed Loop
Open Loop
Standing
Column Well
Thermal
Number of
Capacity
Loops/Wells
per Loop
for 100-ton
or Well
Load
2 tons
50 loops
2 gpm/ton 1 supply well
@ 200 gpm, 2
diffusion wells
20 tons
5 wells
Required
Spacing
20 ft
Minimum 150 ft,
depends on
hydrogeology and
loads
50 ft
Required Land Area
20,000 sq ft
Property must measure a
minimum of 150 ft on one
side to properly space
wells
12,500 sq ft if clustering
wells, or 250 linear ft of
sidewalk frontage
Courtesy of P.W. Grosser Consulting.
Figure 1. An example of a large-scale geothermal standing column well
installation. Courtesy of P.W. Grosser Consulting.
GEOTHERMAL/from page 27
equals 12,000 BTUs/hr). As a comparison, consider that a 500-foot-deep
closed loop generates 2 to 3 tons, he
says (Table 1).
Plus, since a single standing column
well can provide so much tonnage,
the system requires much less space to
install.
“You can actually use the sidewalk
frontage as the drilling site,” Rhyner
says. “It makes sense in the city where
real estate is limited and expensive, or
the project is a retrofit of an existing
building that is built out to the property
line.”
28/ December 2010 Water Well Journal
What Is a Standing
Column Well?
A standing column well system (see
Figures 1 and 2) consists of three main
parts:
●
●
●
the wells and buried connecting
piping (the “well loop”)
an interior plumbing system circulating city water throughout the spaces
to be conditioned (the “building
loop”)
the water-to-water or water-to-air
heat pumps located in the mechanical
rooms.
The heat pumps separate the “well
loop” from the “building loop” and
contain their own refrigerant loop.
“A standing column well can be
envisioned as a long, narrow glass of
water with a straw inserted to the bottom,” Rhyner explains. The “glass”
consists of an 8-inch-diameter borehole
drilled through the soil and into the rock
to a depth of on average about 1500 feet
for commercial installations. The drill
bit and rods are removed. “What is left
is, hopefully, a self-supporting, open
rock borehole,” Rhyner says.
The shallow, soil portion of the borehole is supported by 10-inch or 12-inchdiameter steel casing. The “straw,”
referred to as the “porter shroud,” is a 6inch-diameter plastic pipe inserted into
the completed borehole to the bottom.
The bottom 50 feet of the shroud has
holes drilled into it to act as an intake.
Because the well is open to the rock
formation, groundwater from fractures
and faults in the rock intercepted during
drilling fills the well. A submersible
pump is installed inside the shroud
below the standing water level, near the
top of the well, which circulates the
groundwater through the system. Typical flow rates through a standing column well range from 90 to 150 gpm
depending on well diameter and design.
During operation, the pump draws
water up from the bottom of the well,
sends it through the heat pumps in the
building, and then releases it back into
the top of the well. The water then must
flow all the way down to the bottom
where it is drawn back into the shroud
intake, back up to the pump, and the
cycle repeats.
Heat exchange occurs at two points
in the system. First, in the heat pumps
between the well loop and building
loop; and second, between the circulating groundwater and the exposed rock
in the well.
During cooling mode in the summer,
the heat pumps extract unwanted heat
and moisture from the building loop,
transfer it to the well loop, then it is
released to the rock in the well. In the
winter during the heating mode, the
energy flow is reversed, extracting heat
energy from the rock, delivering it to the
heat pumps which boost the temperature, then transferring it to the spaces to
be heated via the building loop.
Standing column wells are optimally
designed to have a “bleed,” which is
when a portion of the circulating water
NGWA.org
Figure 2. Diagram of a small-scale residential standing column well system.
Courtesy Carl Orio.
Jersey, western Virginia, western
North Carolina, western South Carolina, and northern Georgia. This is a
hilly to mountainous region characterized by thick regolith underlain by
igneous and metamorphic rocks. It is
geologically similar to the Northeastern Appalachian region, except it has
not been glaciated.
“The standing column well has been
applied most successfully in the Northeast because of near surface bedrock
and the presence of clean water at reasonable static levels,” Orio says. “Any
area of the world sharing these characteristics could make equally successful
applications.” Indeed, he adds, he has
heard anecdotal evidence of standing
column well installations in China and
Germany.
The History of the Standing
Column Well
is diverted rather than returned to the
borehole.
“Standing column wells like to work
within a 45- to 75-degree range,”
Rhyner explains. “For example, during
peak cooling periods if the return water
rises above the high temperature set
point, the well is bled, which draws in
ambient-temperature groundwater to replenish the well and bring water temperature back into the optimal range.”
However, it is important to note that
the rock has to be able to yield water at
least at the same rate as the bleed to
avoid excessive drawdown during the
bleed cycle. The bleed water can be
redirected to an irrigation tank, a diffusion well, or be used as cooling tower
makeup water if a hybrid system is
being used, or it can simply be diverted
to a drain.
Bleed rates can range from 3% up to
30%, depending on the installation, says
Carl Orio, chairman and CEO of Water
Energy Distributors Inc., a geothermal
designer and distributor in Hampstead,
New Hampshire, as well as a founder of
the Northeast Heat Pump Association.
Where Can Standing Column
Wells Be Built?
“Standing column wells really can be
used anywhere where rock is located
NGWA.org
close to the surface and is stable
enough,” Rhyner says. “It’s most costeffective where rock is within 75 to 100
feet of the surface.”
These ideal bedrock conditions exist
in only some parts of the United States
—about 60% to 65%, according to Orio.
In the paper “A Survey of Standing
Column Well Installations in North
America” by Carl Orio and others, the
authors found that the majority of currently known standing column wells
exist in the following parts of the
United States (Figure 3):
1. The Northeastern Appalachian region, which includes Maine, Massachusetts, New Hampshire, New York,
northwestern New Jersey, and also
portions of southeastern Canada.
This region is a hilly to mountainous
region characterized by glacial
deposits underlain by igneous and
metamorphic rocks.
2. The Appalachian Plateau and Valley
and Ridge region, which includes
Pennsylvania, West Virginia, eastern
Kentucky, eastern Tennessee, and
northeastern Alabama. This is a hilly
to mountainous region characterized
by thin regolith (weathered rock)
underlain by sedimentary rocks.
3. The Piedmont and Blue Ridge region, which includes southern New
The first known standing column
well originated in Bangor, Maine, quite
by accident, says Orio, whose company,
Water Energy Distributors, perfected the
standing column well ground-source
coupled heat pump approach in the
1970s.
“A homeowner found that his well
didn’t have any yield, so his idea was to
put the water back into the well,” Orio
recalls. Soon after, the well began behaving strangely. “The well began cooling off rapidly in January, and the local
water well contractor just said, ‘Spill a
little water.’ The well quickly rose in
temperature about six degrees,” Orio
says. “This was the genesis of the bleed
effect, and the practical genesis of the
standing column well.”
After the well was studied by Orio
and other geothermal designers in the
early 1980s, it became apparent that the
standing column well could provide a
source of high energy transfer for large
geothermal applications.
During the 1990s, the standing column well was promoted by the Association of Energy Engineers and by the
American Society of Heating, Refrigeration, and Air-Conditioning Engineers.
Likewise, this well design was applied
more frequently in commercial applications. In 1994, ASHRAE granted a research project, headed up by Jeffrey
GEOTHERMAL/continues on page 30
Water Well Journal December 2010 29/
GEOTHERMAL/from page 29
Spitler, Ph.D., PE, of Oklahoma State
University. Orio, who was on the research team, says the publication of the
team’s reports in 2004 resulted in the
first national recognition of the standing
column well. Since 2007, it has been
included in the official ASHRAE
installers’ manual.
Drilling setup along W. 21st Street in New York City for a geothermal retrofit for
two dormitories for The General Theological Seminary of the Episcopal Church.
Photo courtesy of P.W. Grosser Consulting.
Opportunities for
Water Well Drillers
Drilling and constructing standing
column wells is an ideal fit for water
well contractors, even more so than
drilling closed loop geothermal systems,
Orio says.
“When drilling boreholes for closedloop systems, water well drillers can
be undercut on price by the guys who
have the smaller, cheaper machines,”
he explains.
However, drilling standing column
wells requires heavy-duty rigs, more
along the lines of what are used to drill
wells for drinking water. The “almoststandard” standing column well for residential and medium commercial is a
6-inch bore, in the 250- to 500-foot
depth range, Orio says.
“We call that well an ‘8-6-4’: 8-inch
casing into rock, 6-inch bore, and a
4-inch porter shroud with a 4-inch well
pump.”
Opportunities in the Northeast region
abound, and about a dozen water well
drilling companies have taken advantage of this emerging market to further
diversify their menu of services. One
such company is Dragin Geothermal
Well Drilling Inc., with offices in
New Hampshire and Massachusetts.
Dragin Drilling was established
in 1996 by partners Carrie Collins
Quagliaroli and David “DJ” Quagliaroli.
Dragin Geothermal came about a few
years ago, when the partners decided to
establish a sister company to reflect the
company’s growing expertise in geothermal installations. Now, says DJ
Quagliaroli, the original drilling company is all but dormant as the company
focuses solely on this emerging market.
“We constructed our first large-scale
system in 2005,” Quagliaroli says. Now,
Dragin’s project portfolio showcases installations at Harvard, Yale, and various
other institutions all over New England,
30/ December 2010 Water Well Journal
including the heart of Boston. The company also drills standing column wells
for private residences.
“Our workload is about 75 percent
commercial and 25 percent residential
right now,” Quagliaroli says.
So how is drilling a standing column
well borehole different than drilling a
water well?
“When drilling a geothermal well,
one big difference is that it’s not really
about how much water you get,”
Quagliaroli explains. “You need to drill
to a certain depth to meet the requirements for heat exchange.”
You also have to “gear up,”
Quagliaroli says. In addition to needing
a heavy-duty rig, drillers will need auxiliary air compressors and boosters.
Also, there is the issue of handling the
cuttings and water that result from
drilling these deep bores, which can
present a bit of a challenge in tight
urban settings. The cuttings and drill
water have to be diverted into large
plastic-lined roll-off containers. The
water then needs to be filtered on-site
before it can be returned to the earth.
“On a recent job in Bangor, we had
one employee who just handled water
all day long,” Quagliaroli says.
Addressing groundwater quality is
also essential for standing column wells,
especially in urban areas.
“A standing column well is essentially an open-loop system,” Rhyner
says. “Poor water quality can be a deal
breaker. Due diligence is critical. Test
wells are not always cost-effective, but
published groundwater quality data do
exist from federal and state geological
surveys, and a seasoned hydrogeologist
should be able to offer insight into local
conditions. If nothing more, good old
common sense should prevail.”
Groundwater from deep wells can be
highly mineralized or contain high chloride levels. Near the shoreline, salty
water—corrosive to metal components
of a system—should be expected.
Contamination in groundwater is also
a concern when drilling in urban areas,
Quagliaroli says. Rhyner cites a geothermal project in Manhattan that was
cancelled after the wells were drilled
when the water was found to contain
volatile organic contaminants from a
former filling station located on the site.
NGWA.org
“Don’t ever assume that groundwater
in rock cannot become contaminated by
human activities at the surface,” Rhyner
warns.
Drilling in urban areas creates a
whole different list of challenges.
“I present it to owners as ‘short-term
pain for a long-term gain’,” Rhyner
says. “Drilling is loud and it can be disruptive to neighbors. Sidewalks are
closed, and lanes of roads may also need
to be closed.”
Permits and filings can also present
delays, Rhyner says. He recommends
researching whether governing agencies
are familiar with geothermal well
drilling and have regulations in place.
If not, anticipate significant delays and
effort to educate and negotiate with the
agencies.
On a particular job, there could be
layers of people involved including an
architect, mechanical/electrical/plumbing engineers, a geothermal engineer,
geologists and hydrogeologists,
geotechnical and civil engineers,
a sustainability/LEED consultant, a
commissioning agent, a construction
manager, a general contractor, mechanical and electrical contractors, and a
drilling contractor.
“In New York City, it’s rare that even
10 percent of the people involved on a
project have any valid experience with
geothermal,” Rhyner says. “There are
a lot of points where there can be disconnects. Lack of information, poor
communication, and misapplied technology can all complicate or even kill a
project.”
What Is the Future for the
Standing Column Well?
“More engineering firms are opening
up dedicated geothermal divisions now,”
Quagliaroli says. “Right now, the Northeast market is relatively small. There are
maybe a half-dozen drilling companies
who do this kind of work. There is always room for more.”
Rhyner agrees. “We could always use
more drillers to come up to speed on the
technology,” he says. Rhyner adds that
Manhattan and the Bronx are ideally
suited for standing column wells and are
a potential hot market for geothermal installations right now. “Right now, there
are maybe several dozen systems in
place. In my opinion, that’s not a lot.”
NGWA.org
Figure 3. Groundwater regions of North America. Source: Heath, 1988 (with regions
with documented standing column wells shown shaded, Carl Orio, 1999).
Orio, a certified International Ground
Source Heat Pump Association instructor and a certified geothermal designer,
offers monthly two-day training seminars for installing contractors at Water
Energy Distributors, as well as seminars
for engineers, homeowners, and those in
sales and marketing. A new three-day
technical design workshop for engineers
was first held in 2010 and several more
are planned for 2011, the first one taking
place in mid-January.
“Any professional driller can adapt to
this technology,” Orio says, “especially
if they have deep-well experience.”
One new development that could
bloom from the growing acceptance of
the standing column well is the “dualuse” well. A single well is designed to
provide the geothermal heating and
cooling to a home, as well as the drinking water supply. Orio says several
thousand such wells are in existence
since the 1980s and can provide considerable cost savings in new installations.
Others in the industry are carefully
monitoring the safety issues in having a
recirculating well provide drinking
water. Some local health departments
have reconciled this issue, others have
Author’s note: Rhyner’s firm, P.W.
Grosser Consulting, is presently updating for New York City its Geothermal
Heat Pump Manual, originally published
in 2002, and a popular “how to” do geothermal in an urban locale. The new
version should be available on the New
York City Department of Design and
Construction’s Web site in spring 2011.
not, Rhyner says.
Whether they be single-use or dualuse, one thing is clear: the advent of
standing column wells presents a significant opportunity for the well drilling
industry.
As Quagliaroli states quite simply,
“Our industry is lucky to have it.”
Reference
Orio, Carl D., Carl N. Johnson, Simon J.
Rees, A. Chiasson, Zheng Deng, and
Jeffrey D. Spitler. 2005. A Survey of
Standing Column Well Installations
in North America. ASHRAE Transactions 111, Part 2, RP-1119. (Copy
available at www.northeastgeo.com
—click on Library, then click on
Tech Papers.) WWJ
Water Well Journal December 2010 31/