1. 24 July 2014 • Water & Wastes Digest Water & Wastes Digest • Www.wwdmag.com 25
By Janet Rummel
Colorado utility nears
the end of construction
of 50-mile pipeline
B
efore the end of 2014, Colorado Springs
Utilities will lay the final piece of pipe for
one of the largest water projects currently
being built in the western U.S.
The Southern Delivery System (SDS) is a
regional water project in southern Colorado that
will bring Arkansas River water stored in Pueblo
Dam to Colorado Springs, the state’s second larg-
est city, and its partner communities, Fountain,
Security and Pueblo West. Colorado Springs
Utilities is completing SDS at a time when the fre-
quency and volatility of drought is growing in the
arid American West, while the economy is improv-
ing and water demand is increasing.
Fifty miles of predominantly 66-in.-diameter
welded steel pipe serve as the artery of SDS, travel-
ling up 1,500 ft in elevation via three new pump-
ing stations and eventually arriving at a new water
treatment plant north of the dam.
To finish SDS on time and under budget, the
municipally owned utility and its program man-
ager, MWH Global, divided the pipeline into sev-
eral different work packages. Separate packages
facilitated competitive private industry bidding,
which is among the reasons that the project is pro-
jected to come in significantly under budget at
completion, reducing the final projected cost from
almost $1 billion to $841 million.
“The program team has been innovative in
how we have approached SDS—starting with the
design and engineering to contracting and con-
struction,” said John Fredell, SDS program direc-
tor. “We also have extended this ‘outside the box’
approach to how we communicate and inform
interested stakeholders, local residents and busi-
nesses impacted by construction activities.”
The following are a few highlights of the creative
approaches the SDS team used to install the pipeline
in often challenging physical and social conditions.
Ascending From Pueblo Reservoir
The southernmost section of the pipeline, a
4.3-mile section known as South Pipeline 1 (S1),
stood out as one of the most difficult sections to con-
struct due to technical and geological conditions.
Much like a stair step, S1 needed to rise 150 feet
from the reservoir basin and surmount the sur-
rounding embankment in order to level out and
begin its gradual ascent northward. This journey
was complicated by the presence of a railroad line
cut into the surrounding bluff.
The design engineer chose a route between
a drainage way on one side and two 80-ft hills.
After examining multiple options, the SDS
project team determined that the best design was
a 308-ft-long, 10-ft-diameter tunnel at an approx-
imately 3% slope underneath the railroad. A 90-ft
vertical riser shaft situated within the bluff sup-
ported the pipe and tunnel.
Subsurface conditions proved complicated.
The bluff is located just a few hundred yards from
one of the globally recognized sections of the
Cretaceous-Paleogene boundary, the marker bed
of the geologic period approximately 65.5 mil-
lion years ago. Geologically, the bed hosts layers
of limestone and shale, providing both very strong
and very weak subsurface soils.
Construction engineers began work by drilling
a vertical tunnel and installing a riser shaft, rest-
ing it in sand bedding. Then came the arduous
work of digging through limestone. Because of the
slope, tunnel methods such as auger boring and
jack and bore were ruled out. Methods that called
for conveyor discharge or muck cars also were not
practical due to the slope.
Instead, the main tunnel was completed with
the use of a 27-ton road header. Mucking was com-
pleted using a skip bucket attached to a tracked
skid-steer loader.
At the opposite end of the tunnel, engineers con-
structed an approximately 12-ft-wide final cavern
section in the shale, and supported it using rock
bolts at a staggered pattern, steel mesh and shot-
crete. The roof of the cavern intersected the previ-
ously installed sand bedding of the north riser pipe.
Despite such difficult soil and technical con-
ditions, the S1 tunnel crossing was completed
successfully, on time, under budget and to the rail-
road owner’s specifications.
Traversing an ATV Area
After leaving Pueblo Reservoir, S1 pipeline tra-
verses through one of the most well-used motor
sports areas in southern Colorado. Construction
was underway during spring and summer—prime
season for motor sports enthusiasts to ride.
The conventional approach would have been to
establish a linear work area multiple miles long,
stage the pipe sections (66 in. in diameter and 50 ft
long) end to end, and fence off the linear construc-
tion site. That approach would have prohibited
the public from using the many ATV trails that
traversed the pipeline alignment. But because the
SDS team sought to minimize disruption to local
residents, they took a different approach.
Prior to the two-month-long trenching project,
the SDS public involvement team distributed infor-
mational materials to enthusiasts who frequented
the area, and coordinated with both the city of
Pueblo Parks and Recreation Department and
State of Colorado Division of Parks and Wildlife—
the two agencies that co-manage the area. Then,
rather than laying one continuous line of pipe, the
contractor staged the pipe above-ground in islands
and then built several crossings using gates and
fences between the islands of pipe to allow safe
passage through the construction zone.
These passageways were left open until the
actual pipe laying was at each crossing and con-
struction was too intense to keep them open. Signs
were put up encouraging individuals to
use the crossing, but to stay out of the con-
struction areas. This gave off-road motor-
ists the opportunity to enjoy the area. As a
result, there were no complaints from ATV
enthusiasts, and the measures helped pro-
tect public and worker safety by creating
designated safe corridors to cross through
the construction zone.
Engaging Residents in
Pueblo West
Another community engagement chal-
lenge arose in Pueblo West, a community
of 30,000 residents. The 6.4-mile South
Pipeline 2 (S2) section needed to travel
through 125 residential yards and required
the purchase and removal of six houses and
the relocation of their owners.
To keep residents safe and informed and
minimize disruption, SDS staff aimed to be
good neighbors.
Two full-time “construction facilita-
tors” continuously were on site at the
construction areas and served as daily
touch points for residents and businesses.
Through door-to-door visits, meetings
and a 24-hour staffed hotline, the facilita-
tors explained the project and occurrences
that residents could expect. As work pro-
gressed, residents received ongoing visits,
letters, e-mails and newsletters to keep them
apprised of issues ranging from road closures to
plans for yard revegetation.
Even the six homes acquired for demolition
became a community asset. After the project paid
for the owners to relocate, the SDS team offered reus-
able items—such as plumbing fixtures, cabinets and
doors—to the local Habitat for Humanity office to
resell or install in their homes. Local fire and police
departments were invited to use the houses to con-
duct drills and practice simulated firefighting.
By utilizing creative approaches to construction,
coupled with a commitment to communication
and community relations, SDS is advancing a criti-
cal water infrastructure project for four southern
Colorado communities, creating a more certain
water future for its customers. WWD
Janet Rummel is senior public affairs specialist for
Colorado Springs Utilities. Rummel can be reached at
jrummel@csu.org or 719.668.3030.
For more information, write in 1109 on this issue’s reader
service form on page 42.
pipe distribution systems
Finishing Strong
The 6.4-mile pipeline in the Pueblo
West neighborhood had to travel
through 125 residential yards.
Installation of the shaft riser
Several crossings were built using gates and fences to allow
ATV riders to safely pass through the construction zone.
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