Trinity+Church+-+Preservation+and+Restoration

Preservation and Renovation of Trinity Church toc //Nick Dastalfo BAE/MAE, AE 537 2014//
 * Boston, Massachusetts**

__Introduction__
Trinity Church in Boston, MA is one of the most historic and iconic buildings in the northeastern part of the country. This Romanesque church was built in 1871 in downtown Boston by the prominent American architect, Henry Hobson Richardson (Haynes 2003). The building is ornately decorated and constructed using mostly granite and sandstone as well as some more detailed stonework. This church was an engineering feat of its own time as it utilizes a system of wooden piles to support the foundation system in light of the marshy conditions of the Back Bay area of Boston.

Due to water penetration and wear on the building over the past one and a half centuries some of the stone masonry was in need of extensive repairs. Additionally, due to the rise and fall of the water level in Boston, the wooden piles started to experience severe deterioration and strength reducing damage. The church is also home to 33 large antique stained glass windows which have also begun to fall into a dilapidated state. In a major push in the last couple of decades there has been a major push for extensive renovations the wooden piles, masonry work, and stained glass windows were all of high priority.

The following report will chronicle the restoration process as well as describe the extent of the damage and work performed on the building.

__Keywords__
Trinity Church, Boston, Wood Piles, Water Table, Settlement, Stained Glass, Restoration



__Building History__
Trinity church is a long standing monument and figure in the community of Boston. The current site of the church is actually the third Trinity church that has been in operation in the Boston area. Trinity church did not make the move to the Back Bay area until the second church was constructed in 1872 to fulfill the church's need for more space and a new location. The church is located on a 39, 487 square foot lot that has street access on all four sides. This allows the church to be very visible from surrounding streets and neighboring parts of town. The second church was shortly destroyed by the Great Fire of Boston in 1872 and was rebuilt into the structure one sees today. The cost of $435,000 was quite expensive for its time but was necessary in order to realize the great design of H.H. Richardson (Haynes 2003).

The church is constructed in the French Romanesque architectural style but is often called Richardsonian Romanesque which derives it's name from H.H. Richardson himself (WTTW 2012). The front façade is adorned with varying types and colors of granite and sandstone (See Figure 1). The floor plan of the church is in the typical Latin cross style and rises to a central tower that is 372 feet high (Paulson 2003). This architectural gem is located in Copley square in the Back Bay area of Boston amidst other well known building such as the John Hancock Tower (See Figure 2), Copley Place, and the Hynes Convention center. Considering its architectural prowess, it is not surprising that Trinity church was ranked #2 on a list of the "Top Ten buildings that change America published by the American Institute of Architects (WTTW 2012).



Timber Piles
After the first Trinity Church in Boston, commissioned by the Episcopalian Church, was burnt down in the Boston fire of 1872 a new location to build was sought out. The plot of land that was chosen was a relatively small, triangular piece of land in the Boston bay area. This area of Boston is known for it's poor, marshy soil conditions. In a great engineering feat of the time, Trinity church was built atop a matrix of 4,500 timber piles driven into the earth (Lambrechts 2008). These piles were driven into the earth approximately 35 feet and supported four massive granite pyramids which took a large amount of the load from the church above (Haynes 2003). The timbers were constructed of entire trees, cleared of branches, and driven into the ground upside-down. To maintain structural integrity, the piles had to be fully submerged beneath the water or else the combination of air and water could cause rotting. Unfortunately, due to the changes in the water table, this condition occurred fairly extensively. Similar to most wood exposed to both air and water, the timbers began to experience some deterioration. An example of the rot and cross-section loss of the piles can be seen to the right in Figure 3. An estimated 70+ of the original piles are experiencing deterioration that requires engineering attention (Paulson 2003).

Due to the cyclical periods of high and low water table levels in that area of Boston, the piles were oscillating between water and air exposure throughout their lifecycle. Once the piles are exposed to air, the naturally occurring fungi begin to grow and eat away at the piles. This caused the timber piles to begin to rot and lose some of their structural integrity. Some of the piles even at a complete loss of cross-section and load carrying capabilities. The rate of the piles' deterioration is highly variable and occur within a matter of a couple years to a couple decades if the right conditions persist. The rotting of the piles also varies pile by pile based upon the species of tree, where it was grown, as well as other factors. These foundation issues resulted in partial settlement of the building in certain areas. Consequently, the settlement induced higher stresses in the structure and caused masonry failure and cracking as well as cracking of the priceless stained glass pieces.

Water Level in Boston
At the time of construction, the wooden piles would have been placed and cut off below the water level. Since the piles were installed, the water table has dropped for a variety of reasons. One reason for a daily change is the high and low tides of the water. Simply due to the tides, there can be up to a 10 foot swing in the water level (Lambrechts 2008)! Other causes tend to stem from the use and water permeability of the area. Firstly, due to population increase and a greater need for water the sub-terrain storages of water were being pumped out and used by the city of Boston. Simultaneously, as the city of Boston develops and more buildings are built, the area of permeable soil has decreased dramatically. With a greater amount of water being taken and a lesser amount replenishing the underground water levels, the water table inevitably shrunk.

The problem of the lowered water table and pile deterioration was first discovered in 1929 at the Boston Public Library (across the street from Trinity Church) (Paine 1935). Although there were observations of minor exposure of the wooden piles, this only stirred up an awareness for the potential problem. The issue wasn't taken seriously until the 1970's and 1980's and was thoroughly investigated upon the creation of the Boston Groundwater Trust. Since the 80's the water levels have been carefully monitored via 725 observation wells furnished with the proper equipment (Lambrechts 2008).

Masonry Damage
Although some of the masonry work and repair is simply from nearly 150 years of wear on the building, some of the failures could possibly be due to settlement of the building. Once moisture was able to infiltrate some of the sandstone and brownstone on the façade, the expansion of rust from the wrought iron framing and the expansion/contraction of many freeze-thaw cycles multiplied and accelerated the problems (LeMessurier 2014). Many of the doorways, corners, and window conditions have needed repointing or mortar repairs. In locations where the differential settlement under the building was greater, individual blocks or pieces of large stone could be to crack or chip off. This is because the masonry (granite and sandstone) are both brittle materials and fail in a brittle matter as opposed to yielding. some of the excessive cracking on the south side has been attributed to the construction of the John Hancock tower nearby.

===Stained Glass Damage=== Trinity Church is home to 33 exquisite stained glass pieces which decorate then historic church. Most of the initial stained glass pieces were commissioned by noteworthy English workshops such as Burlison & Grylls, Daniel Cottier & Co., Henry Holiday, and Clayton & Bell (Sloan 2014). But of all the decorated stained glass artists, the most famous within Trinity Church would have to be John La Farge. La Farge was responsible for the majority of the murals and painting within the church but also commissioned the four most famous pieces in the church. These pieces, as well as La Farge's work were highly regarded not only because of their beauty but also because of his style. He utilized a new, ground breaking method that had not been used prior. He simply revolutionized the standard for stained glass design with his technique of layering opalescent glass. The opalescent glass has a translucent, milky appearance resulting from the suspension of opaque particles within the glass. The feat creates entirely different light effects from this new composition of glass. This method also allowed two colors to be blended or transitioned together in a single pane. This can be seen in Figure 4 to the left.

Many of the existing windows in Trinity Church are the original French-style stained glass panels placed in the panes nearly 140 years ago! All of the stained glass pieces were commissioned to well known window designers of the time. So at the time of construction, these artistic displays were of the highest quality and workmanship. Due to weathering effects, structural stresses, and poor repairs in the past the stained glass windows were in need of renovation. Much of the issues have arisen due to settlement concerns which stem from the timber pile damage discussed in a previous section. These were further complicated by some failures in the masonry surround the windows.

The recommended treatment for any of the damaged stained glass was for removal, restoration, and reinstallation. This process will include cleaning, adding protective measures, repairing cracks using silicone or epoxy, and possibly recreating broken pieces. The estimated time of restoration for some of the pieces of glass is estimated to be in upwards of 18 months (Sloan 2014).

__Preservation Work__
When the church leadership originally began discussing and planning out the restoration in the mid 1990's, there were 4 goals in mind. Each of which targeting a different need of the congregation yet simultaneously interdependent due to construction limitations and overlap. The four primary goals of the church are listed below and explained individually in greater detail.

1) Restore the deteriorated conditions of the beautiful church 2) Expand the Church for the future 3) Update the HVAC system. 4) Maintain operating conditions during construction.

Restoration[[image:Tension Rod Detail.JPG width="247" height="221" align="right" caption="Figure 5. Photo of some of the detailed murals/paintings within the Church. Courtesy of Trinity Church."]]
In terms of the physical restoration of some of the mortar, stonework, and roofing materials of the building, great care was taken to preserve the classic Romanesque look that the church had become so well-known for. The repairs were carefully done using a surplus of original stone and materials that were found in storage under the church's west porch. The excess of original materials allowed the church to repair all of the visible failures to near authentic quality.

All of the paintings, murals and wall art within the building was also restored. This brought the old faded colors of the historic church back to life. As seen in Figure 5 to the right, the original builders went to great detail to cover every surface with decoration. Because of this fact the scope of some of these restoration was quite large, especially in the nave. Work on the murals and painting was a continuous, constant effort for about a year.

The repair of the wood piles and much of the foundation work was much more complicated than some of the other work above in the super structure. Excavating and getting down to the problem at the pile/capstone interface took a lot of effort. Temporary shoring was needed to support the building as crews systematically went around and repaired the damaged piles. The typical repair for a rotted pile was to remove the top portion that had suffered the most damage due to greater exposure to the air. Steel struts replaced the section of rotten wood to bear the load of the building (Schnabel 2014). The entire excavated area along the tops of the piles was filled in with lightweight concrete. An important concern was being sure to cut the piles low enough where they would be exposed to water and air. Otherwise, the same problem will recur years later at the pile/strut interface.

Expansion
The expansion of the lobby space was not necessarily part of the preservation and restoration of the church, yet very relevant to the work on the church. An additional 13,000 square feet were added below grade at the basement level (Koerth 2010). This expansion was desired to facilitate a growing church congregation in the coming generations. This work needed to be carefully coordinated with other repair work. Additional space for the expansion was not available adjacent to the church, so naturally, beneath the church became the solution. To enable this new creation of space, the basement needed to be lowered by 4 feet. Therefore, this expansion was coordinated and tied into the restoration of the timber piles below as well as the structure above.

The four granite pyramids supported by the wood piles as the primary foundation system was exposed in the expansion process (Kenneth 2014). In both Figure 6 and 7 below, the pyramids can be seen in the corners and edges of the newly renovated space beneath the church.

HVAC System
The aspect of the restoration that seems the most unique is the need for an updated HVAC system. This need was not perpetuated by a particular building failure but by an inefficiency in energy usage. Since the building is so old and was not designed with modern technology in mind, design solutions were limited. Six geothermal wells were drilled on the property to a depth of 1,500 feet (Koerth 2010)! Typically geothermal wells are not used in urban setting because there must be enough space to maneuver and operate the drilling equipment. The small amount of open space enclosing Trinity Church allowed this unique implementation of this system in an urban setting.

===Continuity of Operations=== In order to install the geothermal wells without disrupting the continuity of church activities the contractor had to take special precautions. Additional noise-reducing structures were erected around the drilling sites to limit noise pollution within the church (Trinity Boston Foundation 2014). The number of drilling teams onsite was doubled in an effort to limit the time the equipment would occupy space and create noise. Sarah Wilcox, associate for administration at Trinity Church stated, "One of our goals is to be a good neighbor..."(Trueblood 2002). These extra efforts were performed as a benefit to the church itself but also as a means of respecting the surrounding building occupants and business'. The duration that the drilling teams were onsite was only 6 weeks. Another measure that was taken to reduce the impact on day to day church operations was the type of scaffolding that was used. A series of metal, mobile access towers were used in the sanctuary as opposed to more standard and stationary wood framed scaffolding. The steel poles were tied directly into the buildings granite foundations to eliminate additional framing and support for the scaffolding. A photo of a crew at work using this system of scaffolding can be seen above to the right in Figure 9. The work on the murals and stained-glass in the sanctuary was quite extensive and lasted for approximately a full year. The mobility of the restoration equipment was pivotal in having services and other church functions continue without missing a beat.

__Summary__
All of the above failures, renovations, and preservation efforts play just a small part in the storied history of Trinity Church. If it wasn't for all of the work and money Trinity Church would surely not be as beautiful and well kept as it is today (See Figure 9). These preservation efforts have successfully helped the church maintain it's beauty and functionality in the modern day.

The building failures that occurred at the church were primarily attributed to the pile deterioration that then, in tern, yielded other failures in the masonry and stained glass. Although the deterioration with the piles has been a big concern over the past decades, this is not a recent discovery. With the discovery of this problem dating back to 1929 and the occurrence of wood pile deterioration being somewhat understood at the time, there is no new phenomenon. Despite some of the damage to Trinity Church being attributed to the construction of the John Hancock Tower nearby, these problems were present beforehand and can be explained using our understanding of wood pile foundation. Therefore, this failure can mainly be attributed to the neglect of understanding how the settlement and growth of the city would influence the water table.

__Annotated Bibliography__

 * Haynes, Tim (Aug. 26, 2003). A Church on Stilts. //Science//. The Boston Globe**. 
 * **Article** – Description of the Substructure Engineering


 * Kenneth Castellucci & Associates, Inc. (2014) “Trinity Church Restoration, Boston, MA.”** //**Restoration Projects**.// 
 * **Webpage** – Abstract of the project, contains good pictures of restoration work.

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 * Koerth-Baker, Maggie. (Aug. 11, 2010). “Divine Intervention.”** //**Building Design + Construction**.// 
 * **Article** – Provides background on the church and the need for the renovations
 * Lambrechts, James. Wentworth Institute of Technology. (2008). “The Problem of Groundwater and Wood Piles in Boston.” ASEE (American Society for Engineering Education).** 
 * **Report**: Investigation of deterioration of wood piles around Boston.
 * LeMessurier (2014). “Trinity Church Restoration and Expansion.”**  (Oct. 2, 2014)
 * **Webpage** – Structural Engineer describing scope of the project
 * Paulson, M. (Mar. 16, 2003). Renovation Begins on Boston's Historic Trinity Church. //Knight Ridder Tribune Business News//.** 
 * **Article** – More Details about the scope of the project
 * Paine, Robert Treat (April 1935). The Church Endangered by the low Level of the Ground Water Low the Danger has been Temporarily Avoided**. <[]>
 * **Report** - Historic report published about the initial findings after the pile problem was discovered


 * Schnabel Foundation Contractor. (2014) “Trinity Church” //Project Lists.//** 
 * **Webpage** – Details of Timber Piles deterioration and installation


 * Sloan, Julie L. (2014). "Trinity Church, Boston". //Julie L. Sloan LLC. Consultants in Stained Glass".// Condition Studies**. <[]>
 * **Webpage** -Condition Study and Assessment of Trinity Church

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 * Trinity Boston Foundation (2014). “Preservation work.”**  (Oct. 2, 2014)
 * **Web Page** – Discussion of work and awards received for restoration project
 * Trueblood, David (2002). “Boston’s Trinity Church begins renovations with drilling of geothermal wells.” //Episcopal News Service.//** < http://archive.episcopalchurch.org/3577_20590_ENG_HTM.htm >
 * **Newsletter** – Description of geothermal system installed beneath the church.


 * WTTW(2012). “10 Buildings That Changed America.”** <[]> (Dec. 1, 2014)
 * **Web Page** – Accounts the accolades and well know features of Trinity Church