PAWTUCKET — An architecture engineering firm hired to study the leaking Pawtucket City Hall tower has come up with four solutions and is recommending one — a masonry restoration of $1.1 million — as the best fix.
The Robinson Green Beretta Corporation (RGB), based in Providence, was hired by the city to investigate the problematic tower, which has continued to leak after heavy rains despite an almost $3 million reconstruction project that took place in 2005 to 2006. Maintenance workers have been dealing with the leaks by using an array of buckets and tarpaulins, and the water damage at one point caused the elevator's electrical system to short out.
Public Works Director Lance Hill said the study has been given to the City Council for its review and discussion. He said that RGB's recommendation “is not necessarily my recommendation” and he will be awaiting input from the City Council on the next steps. “At this point, I'm just bringing it to the City Council so we can formulate a plan and move forward,” said Hill.
According to the study, the continual presence of large quantities of water at the base of the tower after substantial rainfall indicates that water infiltration is occurring and the walls of the tower are absorbing more moisture than they were originally anticipated to receive.
In its summary of the problem, RGB found that a reason that the walls may be forced to deal with more moisture than was originally intended may be that a masonry sealer has been applied to the exterior of the tower. Once in the well, the sealer prevents the moisture from evaporation and/or drying and it can freeze within the wall assembly causing the brick to pop or “spall.”
Water that penetrates the wall assembly is typically removed by “weep holes,” and RGB said it was advised that weep holes above windows on the north side of the tower were closed and had since been re-opened. When the weep holes were closed off, water that had entered the wall assembly had no way to escape and backed up inside the exterior walls of the tower.
RGB noted that pressurized water will follow a path of least resistance, and since discharge to the exterior was no longer an option, water trapped within the northeast walls of the tower made new pathways and discharged to the interior tower floor.
RGB has identified four possible solutions to the water infiltration problem: do a masonry restoration, install a “rain screen” system, demolish the tower, or do nothing. Of these alternatives, RGB recommends masonry restoration because it will extend the life of the historic tower and “provide the city with a visual landmark for many years to come.”
RGB wrote that the other options, installation of a rain screen and demolition of the tower, would potentially solve the water issue but would alter the visual image of the historic structure. The firm stated that it does not consider “doing nothing” as an alternative since there would be no gain to the city--only further decay and damage to the structure/tower.
Noting that Pawtucket City Hall was built in 1935 and is listed on the National Register of Historic Places, RGB stated that masonry restoration of the tower would be the least costly option to the city and would ensure a historic landmark for several decades. The firm projected an estimate of $1.1 million, but noted that a comprehensive forensic investigation documenting all existing conditions, extent of previous work and new work required would be needed to establish a more accurate estimate of construction costs. Complete restoration of the tower, if done properly, would be expected to extend the life of the tower for another 30 years before another restoration project would be required, RGB stated.
A second alternative, that of installing a rain screen system, was estimated to cost about $1.3 million. This consists of an outer weather-resistant skin installed over a supporting grid, which maintains a ventilated and drained cavity between the exterior weather-facing surface and the structural moisture-resistant surface. Of various options, a terra cotta rain screen system would provide the appearance of a masonry building, but it was noted that the steel structure of the tower would have to be evaluated to determine if it could support the additional weight of the rain screen without added reinforcement.
A properly installed rain screen system would be expected to last 80 to 100 years, RGB stated.
Dismantling and removing the tower in its entirety was estimated to be the most expensive option, at an estimated cost of $2 million. In order for the structure to be removed safely, the entire tower would need to be staged and “fall protection” provided over the existing building and adjacent pedestrian areas below. Additionally, the infill of the opening where the tower once presided will need to be designed, the study noted.
Lastly, RGB pointed out that if the tower was left alone and no work was performed, the water infiltration would continue and accelerate the deterioration process.
According to the study, continual water infiltration of the tower walls will result in masonry deterioration to the point of complete failure. At that point, chunks of masonry will become dislodged and fall from the building, causing potential liability situations for the city.
The firm maintains that, if left alone, the tower's structural system will eventually deteriorate to the point where the tower itself will become structurally unstable and could potentially fail and fall, “causing a major catastrophe resulting in millions of dollars of property damage and possibly loss of life.”
Also, there would be constant interruption of the elevator service as the electrical components would short out after every rainfall resulting in an inaccessible building and costly maintenance repairs to re-establish the elevator service.
The study also noted that allowing constant water infiltration into the interior of the building will result in destruction of other interior finishes, mold growth, and failure of the main building's structural system “resulting in never-ending costly repairs.”