2001 aci award
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Tecvac, Inc. Receives
Award of Excellence
For Concrete Repair
ecvac, Inc. is the proud
recipient of the National
Capitol Chapter of The
American Concrete
Institute's Year 2001 Award of
Excellence in Concrete Repair for
work it performed at the Historic
Union Station in Washington, DC.
For the second year in a row,
Tecvac has been recognized by its
peers for completing a difficult
project using its exclusive vacuum
processes.
Using its proprietary TecSealtm
Process of leak repair, technicians
successfully mitigated a host of
chronic leaks in the station.
Technicians also performed
structural repairs without surface
destruction or marring of the historic
members.
Tecvac, Inc. is an internationally
recognized leader in innovative
repair techniques for concrete,
masonry and stone using vacuum
technologies. Call today for more
information.
Tecvac, Inc. 39482 Rickard Road
Lovettsville, VA 20180
Office 703 742-9186 FAX 703 742-9231 toll free 800 847-9324 www.tecvacinc.net
For the Second Year In A Row, Tecvac, Inc. Has Been Presented With the
NCC/ACI's Award of Excellence For Concrete Repair
T
K
Chronic Leak Mitigation
Washington Union Station
Washington, DC
Tecvac, Inc.
39482 Rickard Road
Lovettsville, VA 20180
800 847-9324
Union Station Link Ramp Structure 1
Mitigation of Water Intrusion
Washington Union Station
General Description
This project began as a difficult leak repair job. It quickly evolved into a
structural repair project that was merely complicated by water intrusion.
Each time a new area or joint was opened up, it was anyone's guess what
condition the underlying members would be found. On more than one occasion it was
necessary to install emergency shoring because of the extensive deterioration of concrete
discovered. As it turned out, beams and columns were rebuilt, structural steel supports
were installed and prestressed cables were repaired. In one instance, a hole area of ramp
was removed, the cable ends repositioned and the area converted to beam and slab.
After years of leakage, one column was found to be mostly aggregate. The matrix
was so deteriorated that it could be dug into with a pocket knife for several inches.
Because of its position within the Link Ramp, replacement of the column would have
caused long term shut down and long term disruption of ongoing tourist operations. The
contractor used a unique vacuum method where the column was bagged and impregnated
with acrylic repair resin. Total restoration was completed in just two days with no
disruption to operations.
The expansion joints also posed a difficult task of replacement. No less than five
previous attempts by others failed to install a lasting joint. Sometimes within weeks, the
newly installed joints were failed and leaking. The Contractor in this project used a
combination of innovative techniques and materials that have now been in place for
almost two years with no signs of deterioration or leakage.
Union Station Link Ramp Structure 2
Mitigation of Water Intrusion
Washington Union Station
This project entailed mitigation of water intrusion into Amtrak passenger
boarding areas and other areas of occupied space at Washington Union Station. This
proved to be an intense task spanning a range of complexities. From simple concrete
removal and replacement to prestressed cable repairs, the Contractor was more notably
faced with the results of chronic leakage and contamination of a throng of concrete
members and configurations. Although not fully described, the multi-tasked operation
included extensive testing, demolition, structural concrete repairs, expansion joint
removal and replacements, prestressed cable repairs, waterproofing, bearing pad
replacements, emergency shoring, structural steel fabrication and drain installations.
Modeled after the public baths of Diocletian in Imperial Rome, Union Station was
opened to the public in 1907. Departing passengers in the first decades would have
entered the majestic structure from the Western Carriage Porch. Upon entry into the
Main Hall, it is very easy to imagine the bustling throng of travelers from times past.
The Roman Legionnaires still stand behind their shields on the balconies at the
mezzanine level, guarding the tourist and travelers below. Changes have been made over
the years but a chronic problem has existed since construction; water intrusion.
Sometimes it was in the shadows and sometimes it was an open embarrassment.
The proud and imposing structure has been in a constant state of improvement
and repair. While there are reams of history, including war-time take over during WWII
and a horrific crashing of a runaway locomotive in 1953, this water mitigation project
Union Station Link Ramp Structure 3
was of times that are more recent. It is interesting to note however, that when
diminishing rail travel threatened demolition in 1964, the roof had been repaired and
completely replaced a number of times. The station was granted landmark status under
the Historic Sites Act of 1964 and listed on the National Register of Historic Places in
1969.
In 1968, Congress designated Union Station as the site of the National Visitors
Center. The Center was to be operated by the National Park Service. It was at this time
the railroad owners agreed to renovate the main hall for tourist functions and to construct
a parking garage. The garage would adjoin the North face of the station and would
accommodate 4,000 cars and 100 buses. In exchange for the renovation and construction,
the Department of Interior agreed to lease the station for twenty-five years.
In 1973-74, the AMTRAK Improvement Act was passed where Congress
authorized federal funds to supplement development of the Visitors Center. With less
than half of the parking garage completed, and cost overruns approaching $5 million, the
construction work was forced to halt. The Department of the Interior opened an
truncated version of the Visitor Area in 1976, but without parking facilities it was little
visited. By 1978, Visitor Center functions were further curtailed when federal
appropriations were reduced. The whole Visitor Center issue was mired in Congressional
controversy and the uncompleted work at the Station continued to deteriorate until
Congress passed the Union Station Redevelopment Act in 1981. This Act stabilized
funding of the project and, despite numerous disputes and delays, ultimately positioned
dedicated individuals who would transform the Station into the magnificent and complex
structure we visit and travel from today.
Union Station Link Ramp Structure 4
The parking garage was finished by the District of Columbia Department of
Public Works with Sverdrup and Parcel serving as Architects. While a number of pages
could be written regarding the controversies surrounding its construction, let it suffice to
say that the transitions necessary to make the garage an intregal part of the station was a
formidable task under the best circumstances. Consequently, the melding of the Garage
to the Station has been the curse of maintenance and cleanup crews from the beginning.
When this contractor began its work in late 1999, attempt after attempt had
already been made to resolve the water intrusion along the Garage/Station junction line,
known as the Link Ramp Structure. In the previous seven years, diligent attention was
devoted to the water intrusion problem; studies were conducted, testing was performed
and repairs were made. Yet, all efforts proved to be unsuccessful and the water
continued to flow into the occupied space below. Often, AMTRAK passenger waiting
areas were blocked off, passageways were maneuvered around large trash cans used to
catch the water and often, the Metro Station located three levels below would move desks
and office equipment to avoid the incoming water.
After examining the site, reading all the reports and inspecting the previous repair
attempts, the Contractor positively identified no less than twenty conditions possibly
contributing to the leakage. It was found that some of the leaks were easily mitigated,
while others were complicated travels requiring resolutions that were more extensive.
One of the leaks, known for decades to be a "sometimes it does…sometimes it
doesn't" sort of leak was tracked to the louver of a rooftop air handling unit adjacent to
the Ramp Link Structure. In an effort to once and for all take care of the leak, the Owner
Union Station Link Ramp Structure 5
had replaced the entire roof and required that all copings and flashings were to be solder
sealed. Still, the water continued to leak into the passenger waiting area…sometimes.
Although believed to be outside the Link Ramp Area, the Contractor thoroughly
inspected the previously installed roofing system and could find no deficiencies or source
for the intrusion. While the base legs of the air handling unit were closely inspected and
found to be watertight, it was concluded that the source of the leak was positively in the
same location below. Water testing confirmed that rain water flowed from the top of the
unit onto the top louver of the exhaust vents. The louver was mounted with a slight angle
up. As heavier rains filled up the louver, the water would freely overflow the end of the
louver and into the building. Other leaks were not so simple.
The host of possible conditions were ultimately whittled to three primary causes
that included deficient expansion joints, unsealed construction joints and deficient surface
drainage. More importantly, the contractor's inspections also revealed serious structural
problems caused from the chronic leakage. In some instances, where the expansion joints
leaked, the repeated wet/dry deterioration had severely compromised the structural
integrity of the prestressed slabs and beams, and the columns below. This condition
prompted immediate support shoring and reconstruction of the members in a number of
locations.
Another mysterious source of the leakage was found to be a concealed
construction joint located under a sidewalk area that extended 250-300 lineal feet along
the Ramp. When the sidewalk was removed, the whole length of the joint was found to
be open and free flowing into the space below. A gutter system had been attached years
Union Station Link Ramp Structure 6
before to the wall in some areas just below the joint, apparently to divert the flow at some
of the leakage spots.
The joint line was thoroughly cleaned and repaired with polymer modified
patching material. A liquid waterproofing material was vacuum injected into the joint
line and the entire length was covered with an embedded elastomeric waterproofing
membrane before the sidewalk concrete was replaced.
As noted above, the transverse expansion joints located in the Ramp were in a
continual state of disrepair. Despite numerous replacements, it appeared that no joint
could withstand the onslaught of extreme bus traffic and the non-stop automobile and taxi
traffic that utilized access to the garage and station. Many brands and types of joints
were installed, promising long term wear and protection only to find disappointment
within months. Sometimes, within mere weeks the newly installed joints were "flopping"
under traffic and then leaking into the AMTRAK passenger waiting areas during
inclement weather.
The Contractor chose to install a joint manufactured by the D.S. Brown Company.
It was understandable that maintenance and clean up crews were pessimistic when the
Contractor began its work on the joints above. There was even some confidence
expressed (in the form of wagers) that the Contractor's promise would soon be replaced
with the large trashcans used to catch the water.
The deficient joints were removed and the slab edges on either side were repaired
and shaped. The length of the joint was saw cut some twelve inches away and the
concrete was removed to a depth of about two inches. The modification continued across
the joint and up the parapet wall on one end and column on the other. The newly
Union Station Link Ramp Structure 7
exposed surface was vacuum impregnated with acrylic repair resin and the studded steel
extrusion was embedded into the depressed area. The extrusion was embedded with a
specially formulated polyurethane material mixed with graded aggregates and fibers.
When the nosing material was fully cured, the expansion gland was installed. It is
important to note the gland was continuous single piece and contained no welds.
The water mitigation and joint replacements are now well into the second year
with no sign of disrepair or leakage into the station below.
West Ramp of Union Station Link Ramp
Union Station Link Ramp Structure 8
Looking West on Link Ramp
Water Testing Construction Joint Under Sidewalk
Union Station Link Ramp Structure 9
Removing Concrete To Reveal Joint
Water Discovered In Revealed Joint
Union Station Link Ramp Structure 10
Existing Joint Assembly Before Removal
New Joint Extrusion Installation
Union Station Link Ramp Structure 11
New Polyurethane Nosing Material Installation
Installed Joint Assembly
Union Station Link Ramp Structure 12
Severe Condition Revealed Under Sidewalk
Deterioration Damage To Structural Concrete Members Below
Union Station Link Ramp Structure 13
Damage To Interior Finishes
Testing Load On Prestressed Cables
Union Station Link Ramp Structure 14
Total Column Removal
and Replacement
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