POWER September 2011 - 36

TOP PLANTS
1. A tight fit. The compact size of the site
required the engineering team to utilize nearly
every square foot of space. The plant is built
literally to the property lines on all sides. Courtesy:
SNC-Lavalin
tractor mobilized crews to the staging area to
install the platforms and ladders prior to the
sections being brought to the site. Maso emphasized
that " this minimized the amount of
site erection time, which was critical to the
execution plan. "
Two Alstom three-pressure HRSGs were
fully assembled at a site near Tampico, Mexico.
The units were engineered by Alstom specifically
to be transported fully assembled.
The level of completion included hydrostatic
testing, instrumentation and electrical, insulation
of drums and piping, and finish painting.
The units were transported on separate
barges to the Astoria II site. They were offloaded
with multi-axle transporters and set
on their waiting foundations.
A facility in Corpus Christi, Texas, assemCouncil.
That agreement was negotiated
with the union locals and included the understanding
that offsite prefabrication of
major components was the only way the
project could be executed.
Overcoming Construction
Challenges
The main power island for Astoria II was
constructed on a seven-acre parcel of land
fronting the Bowery Bay section of Long Island
Sound on the north and a body of water
known as Steinway Creek on the west. The
compact size of the site required the engineering
team from SNC-Lavalin Constructors
Inc. to utilize nearly every square foot of
space. The plant is built literally to the property
lines on all sides.
In addition, a new 345-kV gas-insulated
switchyard and control room had to be constructed
at the Con Edison site across Steinway
Creek from the main Astoria Energy
site. This highly contaminated site posed a
huge environmental challenge during the
excavation phase, which included more than
1,000 feet of trenching to install two new underground
feeders to tie into the existing 345kV
grid. Significant upgrades also had to be
made at Con Ed switchyards in both Manhattan
and Brooklyn.
Offsite modular construction had to be
maximized in order to both meet the schedule
and allow the plant to be erected on the
limited footprint. The SNC-Lavalin project
team constructed a new berthing dock to allow
barges to dock at site. This was needed
due to the deteriorated condition of the existing
bulkhead, Maso pointed out.
The 275-foot-tall exhaust stacks were prefabricated
by Alstom in the largest sections
possible and delivered, along with the outlet
duct work, to the Port of Newark. The units
were unloaded and transported by barge to a
staging area in New Jersey. The erection con36
bled
six piping utility modules to be installed
at the Astoria II plant. They were loaded
on a single 100-foot by 300-foot barge and
tions posed unique environmental challenges
that were met with success due to the careful
planning and expertise of the field staff, explained
Rowena DeFato, manager of Sustainability/Environment
at SNC-Lavalin.
The Astoria II power plant is located on
property once used for bulk oil storage.
This previous site use resulted in soil contamination
by petroleum products. DeFato
pointed out that the site construction and
site environmental management plans were
supplemented by various other specific
plans needed for such a complex remediation
site. These included a monitoring well
protection plan, water management plan,
soil management plan (including sampling
protocols), and a noise control plan. In addition,
the site was required under law to have
a stormwater pollution prevention plan, a
spill containment and countermeasure plan,
and a facility response plan.
Due to space constraints at the construction
site, several major components were assembled
off-site and barged in.
towed to the Astoria II site. Delivery of these
modules had to be timed with delivery of the
HRSGs in order to be set at a predetermined
point in the execution plan.
The main electrical room was completely
assembled and tested at a facility in Houston,
Texas, and was the largest unit of its kind
ever manufactured by Powell Electric. It was
towed by barge to the Astoria II site and required
two 600-ton-capacity cranes to set it
on its foundation. The Houston facility also
manufactured four smaller electrical rooms.
The 12 cooling fan modules were assembled
at a facility on the Hudson River near Coeymans,
N.Y. These modules were delivered
by barge to the Astoria II site and set in place
by a massive Manitowoc 18000 Series crane.
" The overall coordination of shipping logistics
and unloading of heavy equipment
went off like clockwork, with the great effort
that the team put into motion during the
development of the execution plan and construction
sequencing, " Maso said.
Environmental Issues
The Astoria II project actually consisted of
two separate construction sites: the power
plant itself and the 345-kV substation located
across Steinway Creek. Each of these locawww.powermag.com
" The
physical location of the construction
site also required creative solutions to avoid
adverse environmental impacts, " she said.
" For example, the shallow groundwater did
not allow for the usual concrete wash pit,
so a service was found that would provide
concrete wash bins that, once filled, were removed
and replaced with empty containers.
The project was also able to achieve an average
76% recycling rate. "
Successful Teamwork: Astoria I
and Astoria II
Start-up and commissioning of the Astoria II
facility was completed in June 2011. The Article
X Permit had strict provisions for noise
generated during steam blows that were met
through the use of high-volume, low-velocity
blow methods. The new, combined Astoria
Energy II control room was fully integrated
with the Astoria I plant during a scheduled
outage early in the commissioning schedule.
" The facility achieved the commercial operation
date on July 1, 2011 and is now operating
in conjunction with the existing Astoria
Energy I plant as the largest natural gas power
plant in New York City, " Maso said. ■
-Angela Neville, JD, is POWER's
senior editor.
POWER | September 2011
http://www.powermag.com
POWER September 2011

Table of Contents for the Digital Edition of POWER September 2011
