The Washington, DC Chapter of the Association for Preservation Technology is pleased to announce its Fall 2023 Symposium:

Bridging the Gap between Then and Now: Preservation of Historic Infrastructure


When: September 15th, 2023

Where: The Columbus Club at Union Station in Washington, DC


8:00 AM to 8:45 AM             Breakfast and Registration

8:45 AM to 9:00 AM             Welcome Address

9:00 AM to 12:00 PM           Morning Presentation Session

12:00 PM to 1:00 PM           Lunch

1:00 PM to 3:30 PM             Afternoon Presentation Session

3:30 PM to 4:30 PM             Walking Tour

4:30 PM to 6:30 PM             Happy Hour (optional)

Click here for a PDF version of the Agenda: 2023 APT DC Symposium Agenda.pdf

MorninSession Presentations:

History on the Move: Developing and Preserving the Rock Creek and Potomac Parkway and the Suitland Parkway

Speakers: S. Michael Mitchell and Kate Ricketson | Quinn Evans

This presentation will focus on two unique parkways in the national capital region—the Rock Creek and Potomac Parkway in Washington, DC, and the Suitland Parkway in the District and Prince George’s County, Maryland. Co-led by an architectural historian and a landscape architect, the presentation will outline the developmental history of both parkways, explore the challenges that both parkways face, and detail treatment recommendations Quinn Evans prepared for the Suitland Parkway.

The two parkways reflect two distinct periods of parkway design. The Rock Creek and Potomac Parkway originated with the Senate Park (McMillan) Commission’s transportation plans for Washington, DC, and was designed and constructed between 1916 and 1936. The roadway, connecting Rock Creek and West Potomac parks, reflects the early picturesque goals of the American parkway movement in its winding curves, grade separation, wooded seclusion from the nearby city, and ornamented bridges. The Suitland Parkway, designed and constructed between 1942 and 1944, was officially built as a military highway but served principally as a commuter route into downtown Washington. Over time, the parkway achieved national prominence as an entry point into the nation’s capital for US presidents and foreign dignitaries.

The Suitland Parkway evokes a later stage of parkway design, combining a wide, scenic, and mostly naturalistic corridor following the native topography with wider, flatter curves to accommodate higher-speed vehicles.

Today, maintaining the Rock Creek and Potomac Parkway has required confronting several issues. A rise in graffiti on historic parkway structures such as bridges began occurring with great frequency during the COVID-19 pandemic. A growing unhoused population in the area has resulted in the formation of encampments in public spaces along the parkway, requiring collaboration between District and federal entities to balance the preservation of historic resources and cultural landscapes with a growing humanitarian crisis.

Meanwhile, treatment recommendations for Suitland Parkway will focus on protecting the historic integrity of the circulation corridor while identifying strategies for integrating new trails into the parkway, improving resiliency and stormwater management, and enhancing the parkway’s character to support its use as the dignified ceremonial entrance into the nation’s capital.

Reviving the American Train Depot: Structural Repair and Reconfiguration

Speakers: Margaret Cowie, P.E., and Derek Trelstad | Silman

Across America, monumental structures built to serve a once-vital rail transportation industry are being rehabilitated and reimagined for twenty-first century use. While the architectural and historical value of these structures is widely accepted, their functional value is often less certain. To further complicate restoration efforts, many of the buildings were abandoned or hastily renovated during the 1970s and 1980s after the decline of passenger rail.

Grand Central Terminal (GCT) in the heart of New York City, Cincinnati Union Terminal (CUT) on the edge of downtown Cincinnati, Ohio, and Michigan Central Station (MCS) in downtown Detroit, MI are three stations with surprisingly similar stories. Each was conceived as a major transportation hub for their respective cities and epitomizes the architectural and cultural aspirations of their time. Each experienced a massive decline in the mid-twentieth century and destruction in the 1970s and 1980s – a brutalist tower addition in the case of GCT, partial demolition in the case of CUT, and complete abandonment and vandalism in the 1980s in the case of MCS. GCT and CUT saw a revitalization in the 1990s and now attract a regular stream of visitors through creative and evolving use. MCS had to wait a few decades longer, but soon plans to open its doors as the anchor of the Ford Motor Company’s future Corktown campus.

The structural framing that supports each of these buildings displays the triumphs of early twentieth century engineering. Large, vaulted ceilings, which create the iconic waiting room spaces, are built with thin structural Guastavino tile at MCS and GCT and with curved steel trusses at CUT. But behind the timeless finishes and murals of the main halls are a network of lesser-known and less cared for spaces suffering from neglect or hastily completed alterations, made to accommodate the larger freight operations that typically replaced passenger service. Maintaining the relevance - and revenues - of the vast concourses, corridors, and crannies that make up these monumental train stations is a monumental challenge. In the often-unseen rooms and passages of GCT, CUT, and MCS, preservation and engineering converge to find unique solutions for the rehabilitation of these historic infrastructure hubs that both honor the engineering feats of the early twentieth century while simultaneously adapting the structures for the new demands of the twenty-first century.

Infrastructure Preservation in Fredericksburg, VA: Lessons Learned

Speaker: Andrea Livi Smith, Ph.D | The University of Mary Washington

Like other communities in the DMV, Fredericksburg, VA boasts extensive historical infrastructure. Located at the fall line of the Rappahannock River, Fredericksburg is perhaps most recognized by its rail bridge, which features prominently on the vast majority of promotional materials for the city. Though less well-known, other bridges as well as a canal, an active rail station, and a rail-trail are also important city resources. This infrastructure until recently has been well-used but disparate, with little connectivity between features. However, the city has in the last decade committed to redeveloping the focus on the riverfront as well as improving the walkability and bikeability of the city. These efforts are ongoing, and have faced some setbacks, but overall illustrate how a small city can balance conflicting needs in adapting historic infrastructure to the present - and hopefully the future. This paper discusses major milestones in the preservation of infrastructure in Fredericksburg, paying special attention to lessons learned that are applicable to other cities.

Where Did it Come From & What Does it Mean? The NPS Guidelines for Rehabilitating Historic Covered Bridges

Speakers: Tom Vitanza, RA, AIA, NCARB | NPS HPTC and Christopher H. Marston | NPS HAER

The Guidelines for Rehabilitating Historic Covered Bridges (GRHCB) were published in 2019 yet it is a relatively unknown tool in the historic covered bridge preservationists’ toolbox. Funded by the Federal Highway Administration’s Office of Research and Development in conjunction with the National Park Service, the project started in 2002 with a partnership that included documentation, engineering studies, National Historic Landmark nominations, conferences, publications, and a traveling exhibition all as part of the FHWA National Historic Covered Bridge Preservation Program (NHCBP). At the first National Best Practices Conference for Covered Bridges in Burlington, VT, in 2003, a multi-national gathering of covered bridge historians, timber framers, engineers, public officials, and enthusiasts worked together to draft and ratify “The Burlington Charter for the Preservation of Historic Covered Bridges”. This charter established several goals for insuring the long-term safeguarding of historic covered bridges. It concluded by creating a mandate for “the US National Park Service to develop guidelines that apply and adapt The Secretary of the Interior’s Standards for the Treatment of Historic Properties: with Guidelines for Preserving, Rehabilitating, Restoring & Reconstructing Historic Buildings to historic covered bridges in a manner consistent with these goals and objectives.”

Between 2003 and 2019 the project continued through the maze of requirements that eventually culminated in the GRHCB focusing on Rehabilitation. Members of the historic covered bridge community including public officials, engineers, historians, architects, craftspeople, and covered bridge groupies kept the momentum over the years. This presentation will provide a brief historical overview of the project, the people, the process, the recommendations, the case studies, and the application and potential uses for this important document.

Afternoon Session Presentations:

Infrastructure along the Georgetown Waterfront: A Case Study in the Transition of an Industrial Center to a Recreational Destination

Speaker: Angelina Ribeiro Jones, MLA, MSHP | NPS

This research explores the Potomac River’s identity as a component of the industrial and recreational infrastructure along the Georgetown waterfront. The presentation will describe how the river was harnessed as an armature for a variety of uses including settlement and survival, industry, transportation, commerce, and recreation. Prior to colonization and during the early contact period, the Potomac River attracted settlement by Native Americans including Algonquian-speakers such as the Nacotchtank and Piscataways, who established villages and planted crops in the soils of the floodplain. Georgetown, Maryland was founded as a tobacco port in 1751 (incorporated in 1789) due to its proximity to the Potomac River and the opportunities it afforded for commercial navigation. In the 19th century, the addition of the Chesapeake and Ohio (C&O) Canal (completed in 1850) and the Alexandria Canal and Potomac Aqueduct (also known as the Alexandria Aqueduct) (completed 1843) continued the commercial use of the Georgetown waterfront and increased industrial development at the point of junction between the C&O Canal and the Potomac Aqueduct.

During the beginning of the 20th century, industry in Georgetown continued to expand, even as recreational boating on the Potomac River gained popularity. However, as the century progressed, much of the industrial infrastructure transitioned to recreational use. In 1938, the federal government acquired the C&O Canal and the National Park Service (NPS) took over management of the waterway. The Potomac Aqueduct was superseded by the Key Bridge in 1923 and most of the structure was subsequently demolished. However, the northern abutment of the aqueduct was preserved.

The industries of the Georgetown waterfront started to wane by the early 1960s and most of the industrial building stock east of Key Bridge was demolished between 1969 and 1974. In the present day, the C&O Canal and the Potomac Aqueduct abutment have been rehabilitated as recreational features, which is a key aspect of their preservation.

Other infrastructure built along the Potomac River that intersects with the Georgetown Waterfront that will be discussed in this presentation includes: Foxall/Columbia Foundry, Georgetown Branch of the Baltimore & Ohio Railroad, Potomac Interceptor Sewer, and Whitehurst Freeway.

Resilient Design Behind the Stone Retaining Walls of the Chesapeake & Ohio Canal National Historic Park

Speakers: Adam Rush, P.E. and Gloriana Arrieta Martinez, Ph.D., P.E. | SGH

The Chesapeake and Ohio (C&O) Canal, constructed between 1828 and 1850, stretches 184.5 miles along the Potomac River from Cumberland, Maryland to Georgetown in Washington, D.C. It connected farmers and early industry in the west to the Chesapeake Bay, providing access to a broader market for these goods. The C&O Canal was not a financial success; however, its continual operation between 1850 to 1924 provided crucial infrastructure for trade and commerce. Today, visitors to the National Historic Park walk and ride bicycles along the same rugged towpath where mules previously pulled barges.

The canal consists of a water-filled prism and a towpath that runs parallel to the canal. The historic, dry-laid stone masonry retaining wall that supports the towpath had been damaged by repeated floods, and repairs had not been implemented since the canal ceased operations in 1924. Some portions of the wall had been washed out and other portions were severely deteriorated. The objective of the project was to not only rehabilitate a 0.9-mile stretch of the

historic wall, but also to raise the elevation of the towpath to minimize the frequency of floods and therefore reduce the maintenance required for the towpath, all while minimizing disturbance to the historic fabric of the canal.

The project team evaluated multiple engineering solutions to achieve the project goals of improving the structural performance of the walls supporting the towpath, increasing the height of the towpath to reduce park closures due to flood events, and retaining the historic character of the park. Much consideration was given to modern waterfront construction techniques to see which could be adapted to this historic site. Ultimately, the design team determined that a cost-effective solution to the retain the historic character was to repair and reconstruct dry-laid stone retaining walls. The performance and aesthetics of this system met the design objectives of the park and the design team developed details to reconstruct, extend, and repair the dry-laid retaining wall using techniques to match the historic construction of the

wall. Extending portions of the wall was required to raise the towpath elevation; this posed the most significant challenge given the increased structural demands for the wall. The presentation will go into details of the design and describe how challenges were overcome by the team to fulfill project objectives.

Thanks to this project, a portion of the canal is preserved for the enjoyment of future generations.

Nettle Creek Aqueduct: Considering Previous Failures and Building a Sustainable Future

Speakers: Meg Kindelin, AIA and Kara Johnston AIA| JLK Architects

The Illinois and Michigan (I&M) Canal, a National Historic Landmark, connected Lake Michigan to the Mississippi River via the Illinois River. It played a key role in the development of Northern Illinois. As the I&O encountered larger tributaries, aqueducts were needed to cross these waters requiring considerable engineering.

An aqueduct, in some form, has carried the I&M Canal over Nettle Creek since 1848. The Nettle Creek Aqueduct has experienced seven major reconstructions between 1847 and 1938. The most recent building campaign was constructed in 1933 by the Civilian Conservation Corps (CCC) but was washed away in a historical flooding event in 2013.

A hydrology study concluded that any efforts to recreate the 1938 design would not sufficiently relieve the long-term flooding hazards to the town of Morris. A new, larger, replacement aqueduct was needed to accommodate the rising water levels, and the replacement design balanced contemporary requirements while recalling the historic CCC-era aqueduct. The team encountered several challenges, including:

  • The new aqueduct arch superstructure design, now 4 times the size of the CCC-era design, had to carefully emulate CCC-era precedents and integrate new design parameters. The team analyzed previous failures to developed several design options including single arch spans and multiple arch spans. Ultimately, a 140-foot single arch span was deemed the best solution.
  • A contemporary code compliant stone veneer over a concrete structure had to incorporate accommodation of movement, flexure, control joints, drainage, and support anchorage, while minimizing the visual impacts of these requirements to recall the pattern, type and aesthetics of the CCC-era bridge within a limited state budget.
  • A new concrete mix was developed to match the historic concrete in color and texture to replicate the CCC-era concrete.
  • A new walking/running trail along the elevated canal was integrated as part of the IDNR I&M trail network, incorporating accessibility and other codes.
  • Salvaged historic elements like the wood and iron sluice gate and limestone were reinterpreted along the pathways in new seating and interpretive areas.

Reconstructing historic infrastructure that meets contemporary requirements will be an on-going challenge with climate change. After seven failed aqueducts at this location, this design need to provide endurance for the town of Morris, users of the I&M Canal Pathway, and the people of Illinois.

Restoration of the Arlington Memorial Bridge: Joining Historic Reconciliation with Future Transportation

Speakers: Amanda Lewkowicz, AIA, LEED AP, SITES AP and Charles Thompson | Quinn Evans

How do you achieve the once-in-a-generation restoration of a vital transportation link in the capital of the US? The Arlington Memorial Bridge is listed on the National Register of Historic Places for its significant architectural and engineering design as well as what it symbolizes. Designed by McKim, Mead, & White, it was constructed in 1932 as a symbol of reconciliation between Union and Confederacy by creating a physical link from the Lincoln Memorial with Arlington House, the Robert E. Lee Memorial. The bridge extends the grandeur and procession of the National Mall across the Potomac. Carrying an estimated 68,000 vehicles daily, the 90-year-old structure showed signs of aging with failing concrete and steel infrastructure and damaged decorative elements.

The bridge’s bascule span was a movable steel truss with two leaves that meet over the navigation channel and was active until 1961. This project removed the existing bascule span and replaced it with a fixed structure emulating the original design while retaining the original ornamental iron fascia. To determine an appropriate treatment for the metal architectural components, extensive research was done to identify the original alloy composition and applied finish to both the bascule fascia panels and aluminum balustrade. The fascia panels were held in place and connected directly to the supporting truss. Due to the interlocked nature of this system, the entire fascia truss had to be cut from the structure and be lifted, as one piece, onto a barge where restoration efforts took place. The aluminum balustrade, unlike the fascia, was able to be disassembled and relocated for restoration work. Existing finishes were removed, damaged elements were repaired or replaced in kind, and a new protective coating was applied.

To facilitate the replacement of the concrete substructure of the bridge, all granite and aluminum balustrade and bench assemblies were disassembled. While, as a requirement of the project, the bridge was to remain open during construction with only two days of closure. The quantity of demolition and disassembly presented a challenge to this goal. The design team developed a system of identification that was implemented by the contractor to achieve this while assuring accurate reinstallation.

Walking Tour:

Gilding Restoration Following 2011 Earthquake

Speakers: Michael Kramer and Lisa DaSilva | Gilders' Studio Inc. 

This tour will cover the plaster and gilding restoration in Union Station’s Main Hall after the earthquake of 2011. The work began in 2012 and completed in 2016. We will talk about the structural modifications and repairs which had to take place before the finish work could begin as well as the design and installation of the scaffolding and the investigation of the existing gilding. Since the Main Hall sits atop a hollow space, the scaffold could only cover 20% of the floor in the Main Hall due to load considerations. Also, as a major transportation hub, the scaffold could not interfere with the egress of the thousands of commuters who traverse Union Station every day. Finally, the 8,000 square feet of gilding had to take place in stages and each area had to be 100% complete before moving on to the next stage.  We will walk the Main Hall and also have a chance to access the top of the colonnade to get a close up look at the work.

About the Venue: Designed by Architect’s Daniel H. Burnham and Pierce Anderson, Washington Union Station is a restored, historic, mixed-use, intermodal transportation hub located in the heart of Washington, D.C. Originally opened in 1908, Union Station served as the primary rail transit hub in the city for most of the 20th century, until 1981 when, following structural decline of the building, the National Park service closed its doors to the public. In 1981 the Union Station Redevelopment Act provided funding necessary to restore the building and in 1988 it reopened with expanded retail and food services. In 2015, the Union Station Redevelopment Corporation released a Historic Preservation Plan to guide preservation and restoration at the station complex well into the 21st century.

Registration Fees:

APT DC Member:    $100

Non-Member:          $125

Student:                   $50

We will continue to update this page as more information becomes available.

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