SAK Construction, LLC,
(SAK) recently completed a $2.9
million contract for the District of
Columbia Water and Sewer Authority
(DC Water). The project involved a segment
of DC Water’s Potomac Interceptor
sanitary sewer system, and required SAK
to rehabilitate the aging reinforced concrete
pipe with cured-in-place pipe (CIPP).
When the Potomac Interceptor (PI) was
built following an act of Congress in June
1960, lawmakers couldn’t have predicted
the tremendous growth in the area’s infrastructure.
That law authorized the construction,
operation and maintenance of a
sanitary sewer connecting the new Dulles
International Airport, 25 miles northwest
of Washington, to the district’s sewer
system. It also stipulated that the sewer
should be of sufficient capacity not only
to provide service for Dulles but also for
the expected growth and development in
adjacent areas in Virginia and Maryland.
The PI varies in size from 30-inch to
96-inch diameter, reinforced concrete pipe
in the main trunk to 13-foot by 7.75-foot
rectangular, reinforced concrete pipe in
the lower reaches of the sewer system.
The sewer design included provisions for
interceptor venting at the manholes and
access shafts along most of the sewer system
to promote the exhaust of sewer gases
or the intake of air as needed. Venting is
generally accomplished through ventilated
manhole covers or 12-inch cast-iron vent
pipes that extend from the manholes.
Now over 50 years after its creation, the
PI conveys an astonishing 50 million gallons
per day of wastewater for treatment
from several service areas near Dulles,
flowing to the Blue Plains Advanced
Wastewater Treatment Plant in southwest
Washington, before discharge into
the Potomac River. The PI system consists
of four primary interceptor segments -
Loudoun and Fairfax counties in Virginia,
Montgomery County in Maryland, and the
District of Columbia.
Expanding the Plan
The initial project plan was to line 930
feet of interceptor in a right of entry (easement)
area just off the golf course property.
However, the access was much more
complicated and required additional work
to accomplish the goal.
“The necessary work led to an expanded
segment under the golf course,” said Rick
Travers of Arcadis/Chester Engineers. Travers
is a consultant to DC Water as part
of the Sewer Program Management team
and is onsite at the Blue Plains Treatment
Facility. According to Travers, “Four different
properties were affected, all with
different right-of-entry agreements. A
fifth agreement was reached with Loudoun
Water, since they owned a 72-inch diameter,
6,000-foot-long pipeline that had to
be connected with our bypass. From an
engineering standpoint, this was a hurdle
to get over. If we hadn’t undertaken the
larger project, we would be back to do work
in another 5 to 10 years.”
4 Construction | June 2015 June 2015 | Construction 5
SAK Construction, LLC
By Alicia McMahon
An SAK employee monitors the injection of the thermo-setting resin into the CIPP liner prior to installation into the sewer.
Employees of SAK Construction manage the installation of the liner into one of the manhole entrances to the sewer. Tankers carrying the resin, which
are pumped into the liner prior to installation, are seen in the background. This photo shows more clearly the liner exiting the wetout facility. The silver
tank holds the bulk resin, prior to it being mixed with catalysts and pumped into the liner.
In order to bypass Loudoun Water’s 18-inch Sterling Trunk Sewer, SAK
was required to build a doghouse manhole on the 18-inch sewer. Because
time was of the essence, SAK decided to build a traditional brick manhole
– located about 100-feet from the 11th green. (Photo courtesy of SAK
Construction)
SAK built a doghouse manhole to the right of the 11th green for the bypass pumping, leaving the fairway itself
undisturbed. Much of the actual sewer lining work took place under the golf course, with few golfers even being
aware of the activity. (Photo courtesy of SAK Construction)
Uses Innovative Solution to
Rehab Key Interceptor for
District of Columbia Water
and Sewer Authority
Project Team
• General Contractor: SAK Construction, O’Fallon, Missouri, with a regional
office in Arbutus, Maryland
• Owner: DC Water and Sewer Authority, District of Columbia
• Construction Manager: Bryant Associates, Landover, Maryland
• Design Engineer: Chester Engineers, Pittsburgh, Pennsylvania, with local
offices in Gaithersburg, Maryland, and Arlington, Virginia
• Subcontractors:
- Cleaning and Closed Circuit TV: Doetsch Environmental, Warren, Michigan
- Bypass Pumping: Municipal Hydro Services, Carrollton, Georgia
6 Construction | June 2015
Original project discussions included a
plan that would have created a formidable
challenge for a nearby golf course – the
1757 Golf Club in Dulles, Virginia. The
plan called for rehabilitating the PI system
segment that has sewer lines running
under the club with CIPP, a process that
utilizes a resin-impregnated felt tube that
is generally installed through manholes and
then cured, creating a sewer within a sewer
without any excavations. “CIPP is like a
sock turned inside out; when inverted, the
coated side of the felt tube is then on the
inside of the CIPP liner creating a smooth,
new pipe surface,” explained Bob Stier, SAK
Atlantic Division General Manager.
According to Stier, “Our main obstacle
was the initial process DC Water planned
for the contractors to follow, which called
for installing the CIPP liner through a
new manhole located within the club’s
fairway, which would have created significant
disruption to the course operations.”
He added, “Understandably, the course
superintendent was worried there would
be winter play – people trying out the
course before getting a membership, and
we were sensitive to that situation since
the project occurred during the fall and
winter months.”
To minimize course disruption and to
complete the project on a tight schedule,
SAK devised a plan to sequence their
operations and use only two existing manholes,
off the fairway. As a key first step,
SAK employed Doetsch Environmental
to complete the cleaning of the entire
length of the 48-inch sewer line from
one access point while the line was still
in service. SAK then combined two project
sections using one manhole for installing
the CIPP liner for a total length of 3,000
feet. Another section of CIPP liner was
also installed from one manhole for an
additional length of 2,000 feet.
The flow bypass from the project was
between 16 and 20 million gallons of main
flow per day, with two secondary flows
that were each less than a million gallons
per day. As part of the CIPP process, SAK
did live flow cleaning of the pipe to remove
any remaining debris. “This is a necessary
step in the CIPP process,” noted Travers,
“but it also saved SAK time, and therefore
saved money on the project.” The bypass
pumping system, completed by Municipal
Hydro Services, consisted of four, 12-inch
and eight, 8-inch pumps for the mainline
bypass operation. The two sideline
connectors were each bypassed with one,
6-inch pump.
Within Budget, Ahead of Schedule
The project was completed five months
ahead of schedule, including cleaning and
re-inspecting, with final testing in early
March. Surface restoration was completed
at the end of April, including any areas
disturbed adjacent to the actual course.
The project bids came in within DC Water’s
budget and included a $90,000 allowance
for restoration of disturbed areas on 1757
Golf Club fairways. None of that allowance
was needed due to SAK’s sequencing of the
CIPP installation.
“Originally, the club owners thought
we would need to work directly on their
property over the Potomac Interceptor;
however, our innovation and process permitted
us to complete the project without
disturbing the integrity of the course. This
was a complicated project that required
SAK to configure the necessary bypass
pipelines in a way that would not impact
the surrounding areas or operations of the
golf course,” Stier said.
“With our seasoned team of CIPP professionals,
we achieved this and have
handled additional complexities of the
project without delays or disruptions.”
Travers agreed, saying “In the end, the
significance of the project involved SAK
working in partnership with DC Water
to restore critical parts of an aging sewer
systems, giving this segment another 50
years of life.”
At the site of Inversion No. 3, the liner can be seen as it moves from the onsite wetout facility to the inversion tower. Prior to this, thermo-setting polyester resin is pumped
from the tanker truck (background) to a static mixer, combined with a catalyst mixture, and pumped into the dry liner where it is impregnated into the layers of felt. The
final product (as seen in the photo) is then inverted (turned inside-out) and directed into the manhole and finally into the sewer to be lined.
Project Schedule
Initial work began on this low-bid project in December 2014, when Doetsch
Environmental began cleaning and closed circuit TV inspection of the PI. This was
followed by the installation and testing of the bypass pumping system. The first
CIPP installation began on January 9, 2015 and the third and final installation was
completed on January 27, 2015. Notice to Proceed was issued in November 2014
with final completion scheduled for July 17, 2015.
There were two milestones on the project. Milestone 1 called for all work between
Manholes 61 and 64 to be completed by February 15, 2015, and milestone 2 called for
all work between Manholes 64 and 66 to be completed by March 15, 2015. Despite
installing the CIPP liners in the opposite order of the milestones, SAK was still able
to complete the installations on time and within the milestone time frames, earning
contractual incentives in the process.
Working above