by Kelly Streeter
I had the opportunity to visit John Canning Painting, Plastering and Conservation Studios in Cheshire, CT last week. Bill Barry, John Riccio and I met to discuss the application and customization of the TPAS software to the types of plaster surveys they routinely do. While there, I was able to tour the studio and get a sneak peak at the murals they are designing and executing for the Cathedral of St. Patrick in Norwich, CT. What a treat.
The Old Post Office building in Washington, DC, constructed between 1892 and 1899, was designed by Willoughby J. Edbrooke, the Supervising Architect of the Treasury Department. Purpose-built to house the Post Office, it is considered the last significant building of the Romanesque Revival style constructed in Washington DC. It was also the first building in the city to incorporate a steel frame to support the interior structures of the building while exterior granite (Vinalhaven, ME) is load-bearing and tapers from 5’ thick near the foundation to approximately 1’ thick at the eave of the mansard roof.
In the 1880s Congress approved the building of a new post office. Planned to be a grand edifice to act as an anchor to revitalize the neighborhood between the Capitol and the White House, the construction dragged on for seven years. By the time it was completed the Beaux Arts style of architecture had gained favor making the newly completed Post Office appear almost immediately outdated. In fact, the new structure was derided in the New York Times as “a cross between a cathedral and a cotton mill”. The post office moved into the new headquarters when it was completed, but in 1914, the Mail Depot was moved to a larger building constructed next to Union Station, leaving the purpose built landmark underutilized. Since the 1920s the massive structure has served as overflow space for various government agencies.
In the 1920s the building commission of the Treasury Department was actively developing the surrounding Federal Triangle complex and promoting the building’s demolition. This act was only suspended by the deepening depression: the government could not afford to tear the building down. Given its mixed use and orphan status with no government agency directly responsible for its upkeep, the Old Post Office slowly fell into disrepair. In 1964 the Pennsylvania Avenue Commission, organized by President John F. Kennedy, recommended that the building be demolished to make way for the completion of the Federal Triangle. By the early 1970s, demolition permits were in place and the funds for the demolition were appropriated by Congress.
The building narrowly avoided the wrecking ball again when a preservation group led by Nancy Hanks, the then chairwoman of the National Endowment for the Arts, prevailed upon Congress to reverse its decision. The building was added to the National Register of Historic Places in 1973, treated to an extensive renovation beginning in 1976 and officially renamed the Nancy Hanks Center in 1983.
In early 2012 The Old Post Office building was deemed surplus building stock by the General Services Administration, which entered into a long-term lease agreement with The Trump Organization, whose plan is to rehabilitate the building as the Trump International Hotel Washington, D.C. Vertical Access worked with Robert Silman Associates for the Trump Organization to complete the due diligence survey in advance of the lease of the property. In August 2012 a VA team completed a thorough exterior survey of the tower and areas of the main building.
WASHINGTON — To the myriad indignities suffered by Congress, including stagnant legislation, partisan warfare and popularity on a par with petty criminals, add this: the Capitol’s roof is leaking, and there is no money to fix it.
The Capitol dome, the nation’s grandest symbol of federal authority, has been dinged by years of inclement weather, and its exterior is in need of repair.
The dome has 1,300 known cracks and breaks. Water that has seeped in over the years has caused rusting on the ornamentation and staining on the interior of the Rotunda, just feet below the fresco “The Apotheosis of Washington, which is painted on the Rotunda’s canopy. Continue reading article in New York Times
Driving along the San Miguel River near the historic town of Uravan in western Colorado, one has to study the cliffs to find remnants of a 10 mile long structure built 120 years ago. Constructed by the Montrose Placer Mining Company between 1889 and 1891, the Hanging Flume ended its service life in 1903 and has since succumbed to weathering, rock fall and plundering by locals in need of timber.
With much of the structure long gone and few existing original documents and photographs, myriad mysteries surround the construction process. Did the workers use a steam engine powered drill, or were the thousands of anchor holes in the sandstone drilled with only a hammer and chisel? How were the frames weighing more than 300 pounds moved into place? These and other questions have stirred up a “flume fever” in residents of neighboring communities. It is known that at its completion, the Flume was a 10-mile long series of wooden and earthen troughs carrying 80 million gallons of water per day to gold mines.
In 2004, Vertical Access teamed with Robert Silman Associates, Anthony & Associates and Western Colorado Interpretive Association (et al.) to document representative sections of the Flume. Eight years later, VA technicians returned to the Flume to begin a new phase of work.
Keith Luscinski and Donn Hewes were on site February 10-12 to gather more information on one particular “hanging” section, that is, a section that was built on the side of the cliff. Taking dimensions and recording deterioration, the two technicians gathered information to prepare for reconstruction of the 50-foot long section that is slated to take place in April. The building process will not only help answer questions about the original construction techniques, but also provide residents and visitors of the area with a representation of the original structure.
Vertical Access will be working with other members of the project team over the next two months to acquire the necessary timbers and arrange construction logistics. As part of the preparation process, VA has constructed a 1/8-scale model of two sections of the Hanging Flume. The model has already proved valuable by providing insight into the assembly process. Stay tuned for updates on the final product in April!
by Kelly Streeter, PE
I joined Evan and Keith at the Confederation Building in Newfoundland in May to complete a nondestructive evaluation pilot project designed to challenge our conclusions from our hammer sounding study of the limestone units. While in some cases it may be easy to detect delaminations by hammer sounding alone, the variable installation details at the Confederation Building made it very difficult to confidently predict by ear whether or not a stone “sounded” delaminated.
By using ultrasonics we were able to evaluate the stone’s response to a hammer hit in both the time domain and the freqency domain. As Evan mentioned in his post, we had the added advantage of easily-accessible, known-delaminated and known-sound units which had already been removed for the renovation of the building’s west wing. Not only were these units easily accessible, we could clearly see the delaminations in some of these removed units. We tested those first to calibrate our observations. It was fairly easy to see the multiple reflections from the delaminated stones, marked with arrows in the plot below, as opposed to the one clear reflection from the sound stone.
We then plotted the power spectral density, or PSD of the recorded hammer hit. The PSD allows us to convert the power of a signal, as measured over time, into the frequency domain, showing us clearly in numerically and visually (on a graph) what our ear is trying to parse out. Using this method we can analyze the way the frequency content changes from one stone to another.
The calibration went very smoothly. We found that we could easily identify the differences in both the time and frequency domain plots between the sound and delaminated stone units. We took these observations to the wall to test two different areas on the tower.
And then came the hard part.
It was a challenge (to put it lightly) to manage the rope access equipment, the tablet computer and the hammer and receiving transducer and all of the associated cables. I found myself wishing I had two more arms.
Another significant challenge was the weather. We had to battle the frequent, low-level mist and rain throughout our visit. I was attempting to get the data but not expose the electronics to excessive moisture.
In the end, it was an excellent and rare opportunity to apply different nondestructive evaluation theories derived for more modern structural materials like concrete and pavements, to dimension stone. We discovered that we could quite easily detect delaminations once we had calibrated the equipment to a known condition.
Imagine what the Norse sailors who first settled the site now known as L’Anse aux Meadows in Newfoundland must have experienced traveling across the Atlantic Ocean 1,000 years ago; or what the English explorer John Cabot felt when he purportedly landed on Newfoundland at the end of the 15th century. These sailors, venturing west from northern Europe, found the edge of a new continent. While a four-hour delay on the outbound flight and a cancelled return flight are hardly hardships compared to what these early explorers suffered, they do make one realize that St. John’s, only three hours from New York City by airplane, is still an insular and isolated place.
Following Cabot, explorers from other European countries landed on the shores of Newfoundland, and in 1583 Sir Humphrey Gilbert declared the island to be a colony of England. Although France was granted land rights to parts of Newfoundland in 1713, the island was effectively a British colony until 1907 when it acquired dominion status. Finally, a tightly contested referendum held in 1948 determined that Newfoundland, together with Labrador to the north, would become a province of Canada.
The Confederation Building, constructed in 1959-60, was built to house the Newfoundland and Labrador House of Assembly as well as other government offices for the newly established province. The building consists of an eleven-story tower with three to five story wings on three sides of the tower. The exterior is mainly clad in brick, with St. Marc (Quebec) limestone used at the parapets and window surrounds.
Exterior renovations began in the fall of 2009 to address the deterioration of the window systems and masonry cladding. With work at the west wing ongoing, Vertical Access was retained by Erik Jokinen to assist with the investigation of the limestone on the tower. During three days of field work this week, Vertical Access technicians Keith Luscinski and Evan Kopelson performed a hands-on inspection of the upper areas of the tower, documenting masonry conditions and hammer sounding over 1,000 limestone units. Kelly Streeter joined Keith and Evan for two days on site to perform a pilot study on the use of acoustic emission as part of the investigation.
A key question in the study was how to identify blind delaminations that may not be visible on the exterior surface of the stone and are difficult to detect by traditional hammer sounding. As part of the pilot study, acoustic emission, a nondestructive techniques based on ultrasound, was applied to stone units previously removed from the west wing of the building. Both sound units and units with visible delaminations were tested in the pilot project setup. Following calibration of the testing procedures to the specific stone used on the Confederation Building and type of delamination encountered, Kelly performed ultrasonic testing at two areas of limestone at the top of the tower. Initial results are promising in being able to identify blind delaminations based on the frequency pattern of the acoustic emission. Also evident from the pilot study is the need for careful calibration to the specific conditions likely to be encountered.