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HOBAS for Penstocks
Newsletter | No. 60 | January 08
·
Meandering through the White
Mountains, a large wooden penstock
served as the main water supply for a
local hydro facility. Jackman Station, as
the facility is referred to, is fed by the
Franklin Pierce Reservoir, which was cre-
ated by the hydros dam and surrounding
earthen dikes. The water elevation in the
reservoir is managed according to spring
run-off.
Public Service of New Hampshire
(PSNH), the Granite States largest elec-
tric utility, serves more than 475,000
homes and businesses. PSNHs power
generation facilities consist of nine hydro-
electric plants, including the Jackman
Hydro station, which was built in 1926.
This facility, located in Hillsborough, has
been serving the area for years, but the
penstock was approaching the end of its
service life.
HOBAS for Penstocks
Reliable CCFRPM
Prior to the recent improvements, 5,000
feet of wood stave penstock extended
from the Franklin Pierce reservoir to a
surge tank upstream of the powerhouse.
This 7.5-foot diameter penstock was
made up of vintage wood stave sections,
circa 1926. Repairs were undertaken in
1954 and in the 1970s, yet the down-
stream sections of the wood penstock
still leaked badly. This leakage caused
icing problems during winter months and
required constant maintenance. In 2003,
the penstock had a significant rupture
that impacted abutting properties. To
prevent future failures and ensure reliable
operations of the hydro facility, repairs to
the existing penstock were necessary. In
C
O N T E N T S
3 | Product Profile
The Performance
Advantage
4 | H O B A S U s e d o n P e a c e
P r o j e c t
6 | High Point Picks HOBAS
C
ONTACT
HOBAS PIPE USA
www.hobaspipe.com
info@hobaspipe.com
tel.: (281) 821-2200
Continued on page 2 THE HIGH STRENGTH AND CORROSION RESISTANT HOBAS PIPE HAS MANY
ADVANTAGES IN PENSTOCKS.
2 |
HOBAS PIPELINE 1/08
a series of contracts, PSNH decided to
replace the remaining wood stave pen-
stock with a new pipeline.
Kleinschmidt, headquartered in Pittsfield,
Maine, that specializes in energy and
water resource projects, was retained to
develop a feasibility study and engineer a
replacement pipeline. Kleinschmidt ini-
tially evaluated five pipe material options
for the penstock replacement: wood
stave, concrete, HDPE plastic, steel and
fiber reinforced polymer (FRP). Factors
that led to the final determination includ-
ed the structural reliability, corrosion
resistance, hydraulic capacity, ease of
installation (pipe weight) and perform-
ance history of the pipe material.
Kleinschmidt provided their evaluation
and recommendations to PSNH, which
chose the fiberglass pipe option and pur-
chased CCFRPM pipe manufactured by
HOBAS PIPE USA of Houston, Texas.
Design Considerations
The corrosion resistance and relative
stiffness of FRP pipe meant it could be
supported on the existing grade and half
buried, rather than placed on saddles or
completely covered in a buried trench.
This design flexibility, combined with a
longer projected service life lead to a com-
petitive total construction cost for the FRP
alternative, stated Keith Martin, a project
engineer and civil/structural engineer with
Kleinschmidts Pittsfield, Maine, office.
The lower frictional resistance of HOBAS
compared to other materials allowed the
replacement pipe to be reduced to a 7-
foot diameter without additional head
loss, stated Martin.
The pipe was half buried in the shallow
trench of the existing penstock, requiring
minimal excavation costs and low environ-
mental disturbance. Approximately 300
feet of the new penstock were supported
above ground on steel saddles to accom-
modate the topography as well as mini-
mizing the impact to the wetlands that the
penstock crossed.
HOBAS REPLACES WOOD STAVE PENSTOCK
Continued from page 1
SOME OF THE PIPE WAS INSTALLED
ON CRADLES TO MINIMIZE THE
ENVIRONMENTAL IMPACT. HIGH
STRENGTH HOBAS PIPES ARE IDE-
ALLY SUITED TO ABOVE GROUND
APPLICATIONS.
HOBAS CCFRPM is manufactured by a
unique computer controlled centrifugal
casting process. To achieve the higher
axial strength necessary for the above-
ground installation, additional reinforce-
ment is placed in the longitudinal direction
during the manufacturing process,
explained Rene Garcia, Sr. engineering
associate with HOBAS Pipes Houston
manufacturing facility. The design flexibil-
THE LIGHTWEIGHT HOBAS FIBER-
GLASS PIPE SECTIONS WERE CAR-
RIED TO THE POINT OF INSTALLA-
TION AND ASSEMBLED USING THE
SINGLE EXCAVATOR VISIBLE IN THE
BACKGROUND.
Continued on page 8 HOBAS PIPELINE 1/08
| 3
Consistent Quality and Performance
·
Most U.S. municipalities have HOBAS
pipe in their systems and the use of
HOBAS pipe in the USA is expanding
faster than ever after more than 20 years
of reliable performance. More than 40,000
miles of HOBAS pipe has been installed
around the world.
Versatile
HOBAS pipes can be economically
designed for non-pressure and pressure
service by varying the quantity, placement
and orientation of the glass-fiber rein-
forcements.
Smoother Surfaces, High Flow Capacity
HOBAS Pipe is manufactured with a
unique, precise, computer-controlled,
centrifugal casting process that no other
method can deliver. This produces very
consistent, high-density pipe with a mold-
smooth exterior surface and a glass-
smooth nonporous liner that is resilient
and abrasion resistant. In addition to
superior hydraulics, thin-wall construction
produces an oversized I.D. for the highest
flow capacity available.
The Performance Advantage
Leak-Free Joints
Another HOBAS advantage is push-
together joints for a 100 percent leak-free
pipeline that preserves the streets above
and reduces treatment costs.
Straightforward Installation
Installation is quick and easy with pre-
dictable, reliable pipe performance by
every method. Push-together joints are
simple and fast to assemble. Lightweight
pipes are safe and easy to handle, often
with the smaller equipment typically on
the site. 4 |
HOBAS PIPELINE 1/08
Continued on page 5
·
In 1986, the United States Congress
established The United States Institute of
Peace (USIP) and has provided $100 mil-
lion for construction of a permanent head-
quarters facility in Washington D.C. It will
be located at the northwest corner of the
National Mall, facing the Lincoln Memorial
and adjacent to the Korean War and
Vietnam Veterans memorials.
Construction of the facility is scheduled
for completion by the first quarter of 2010.
However, there is a great deal of work to
be done prior to groundbreaking. This
includes shoring the existing infrastruc-
ture. The United States Institute of Peace
Sewer Rehabilitation Project will ensure
structural integrity to the existing brick
sewer that is located under the proposed
building site.
HOBAS USED ON PEACE
PROJECT
Structural Requirements
The District of Columbias water and
sewer authority, DCWASA, operates
1,800 miles of sewers and provides retail
water and wastewater services to its cus-
tomers in the district. DCWASA is
charged with ensuring reliability of the
areas infrastructure. A brick sewer that
was reportedly built in 1896 has been
serving the area. Although it was in fair
condition, with only a few repairs required
in recent years along its entire length,
planners decided that it needed perma-
nent preservation to support future con-
struction.
They also decided that slipline rehabilita-
tion was necessary to ensure the sewer
would not interfere with the future USIP
facility. HOBAS centrifugally cast, fiber-
glass reinforced, polymer mortar
(CCFRPM) pipe was the only product that
met all of the project requirements. The
new CCFRPM sewer is structurally
sound, leak free and provides adequate
capacity.
Randolph Rostas, senior project manager
with the engineering firm of Metcalf &
Eddy (M&E), Washington, D.C., was
design engineer for the project. Project
manager was Naveen Krishnamurthy from
their office in Baltimore, Md. Their engi-
neers evaluated the existing site condi-
tions as well as the building proposals.
The approximate ground profile now
exists 40 feet above the top of the exist-
ing sewer. Depending on which of the final
designs for the USIP building is adopted,
the proposed lowest level of the slab
could be just five feet above the existing
sewer. Regardless of the final design, the
pipe to be installed had to be structurally
sound, grouted in place and capable of
handling the final loads.
Preserving Capacity
The existing brick sewer was sliplined
with 360 linear feet of 69-inch diameter
HOBAS CCFRPM pipe. The actual inside
diameter of the original brick sewer varied
from location to location but was general-
ly 73 to 75 inches. M&E thoroughly evalu-
ated the host pipe conditions in order to
maximize the diameter of