Fort Washington Stabilization Project

by Chris Mayo
Since 1809, Fort Washington has guarded Washington, D.C., from its perch above the Potomac River. Originally completed in 1809, the Fort was destroyed by its own garrison in 1814.

Reconstruction began almost immediately, and a new fort was completed in 1824. An extensive remodel was completed in the 1840s and the first cannons were mounted in 1846. Since then, the majestic brick and stone structure has stood as a lone sentry overlooking the river.

Although the fort’s guns were replaced and upgraded through the early 1900s, the basic structure has remained unchanged since it served as an Adjutant General’s School during World War II, after which responsibility for the fort was transferred to the United States Department of the Interior.

As is the case with many buildings of the era, maintenance was performed sporadically and often with less than optimum attention to historic detail. Original brick was repointed with cement mortar rather than with the lime-based mortars that were used until the early 1900s. Cosmetic repairs were made to the deteriorating aspects of outer areas, while underlying out-of-sight features remained untouched. Predictably, the proud structure slowly decayed over the years.

By 1999, it became obvious that without considerable repairs the fort would soon reach a state of disrepair from which it might not recover. A section of wall had collapsed, other walls were deteriorated and bulging, and severe leakage and erosion had become significant issues. The National Park Service decided that for the fort to survive, full-scale stabilization would have to take place.

The Christman Co. of Lansing, Mich., was contracted to manage the project. Christman was chosen because since 1894, the company has built a reputation for both new and restorative project management, and because they are known for the ability to assemble collaborative teams for projects. True to form, the contractor worked with Lord, Aeck & Sargent Inc., an architecture firm based in Atlanta, in conducting a condition assessment and completing a priority list. The superior-slope wall was bulging and showing water damage from top to bottom. Stonework on the main entry archway was cracked and threatening to break apart. The upper terreplein (the gun placement decks behind the superior slope) was heaved and cracked, and the drainage system and southern slope were damaged and eroding. Each required unique solutions. Schiffer Mason Contractors Inc. of Holt, Mich., 4SE Structural Engineers in Charleston, S.C., and CMC Ltd. Materials Consultants, United Kingdom, rounded out the team that would complete the work.

The main entryway to the fort, an elegant stone archway, was suffering from neglect — showing deteriorating mortar joints as well as damaged and spalled stone. Fortunately, most of the damage was limited to those areas most exposed to the weather, and the stone behind the spalls was still in acceptable condition. After brainstorming to come up with a way to repair the archway while retaining the original look, the team decided to utilize pieces of the good stone on the face of the entryway. Utilizing a Dutchman technique, it was possible to attach the stone to solid masonry deeper in the wall using steel staples. This method enabled the team to use original stone in the repair.

The challenge of the superior-slope wall, though much more detailed and labor-intensive, was solved in much the same way. The superior slope inclines from 5 feet at the low point to 35 feet at the highest. Like many masonry walls of the time, the base of the wall is far wider than the top. Essentially the superior slope is four walls — two visible outer walls tied to two inner walls with a cap on top. The bulging was the result of the failure of the ties, or delamination — the outer walls were separating from the inner. “There was a tremendous amount of moisture in the wall, and if we had only fixed the masonry without resolving the moisture issues, the problem would eventually return,” says Dan Schiffer of Schiffer Mason Contractors. “We all recognized that we would have to create a means to drain the water away from the wall, yet we had to do it within a historic context.” They came up with stepped lead flashing, which would allow the wall to shed water. “Using lead allowed us to create flashing that will work and is within historic context,” says Schiffer.

In addition to the water issues, much of the brick on the exterior of the wall was damaged or stained from cement mortar repointing. As the wall was disassembled, craftsmen were able to salvage enough brick from the inner walls to replace the damaged brick on the new outer wall. Steel ties were utilized to bond the inner walls and outer walls. Intricate scaffolding was designed to allow the masons to work on the wall without damaging the earth and foliage at the base of the wall, a particular concern of the National Park Service.

It turned out that water was the underlying problem on the terreplein decks as well. At some point, a slab had been poured to repair the problem, but it had exacerbated it instead. Water had leached underneath the slab, increasing the rate of deterioration. A need for a new slab was obvious, yet measures had to be taken to ensure that the same water problem wouldn’t recur. The team decided to pour a new slab and add a layer of sealant on top, then used salvaged brick interspersed with new brick to return the surface to as close to its original condition as possible.

While the entryway, superior slope and terreplein decks presented the most complex issues, myriad other deficiencies in the fort were also addressed. The drainage system in the main esplanade (on the ground level) and the brick and cobblestone trenches leading to brick-lined drainage pipes required repointing and restabilization. Ultimately, PVC lining was installed in nonvisible areas as a means to guide water to the historic drainage pipes. The soldier’s barracks and officers’ quarters were repointed, and the slate roofs were repaired with Virginia black slate mined from the same regional area as the original slate. The south slope (from the fort to the Potomac) required stabilization, as years of erosion were taking their toll. Caissons and soil nails capped with concrete were used, allowing reinforcement without disturbing the natural greenery.

“It took a lot of discipline to focus just on stabilization,” says project manager Gary Scheuren. “When you’ve been involved in historic restoration for a while, the tendency is to want to fix everything.”

Overall, one final facet of the Fort Washington project that stood out was the ease with which the major players collaborated, an observation made by each person interviewed for this article. “Lord, Aeck & Sargent enjoyed working collaboratively with The Christman Co. and Schiffer Mason Contractorsry,” says project manager Robert Wanderman, AIA. “Resolving the complex issues inherent in historic fort construction required input from each firm’s expertise.”