The 20 Mass project located at 20 Massachusetts Ave. NW. in Washington, D.C., was recognized as the Best Project in the Office/Retail/Mixed-Use category for the 2024 MidAtlantic Best Projects awards.
The 1970s-era, seven-story office building was completely transformed into a 485,000 SF mixed-use destination, featuring a 274-room luxury hotel, Class-A office space, and amenities. To achieve this, the building’s exterior and interior were stripped down to its structural frame, and three new floors were added, expanding the space by 101,000 square feet.
Permitting Public Spaces
Bohler DC handled the site civil engineering design and permitting. One of the main challenges involved obtaining permits for the high-quality public space that developer, The RMR Group, had envisioned. In Washington, D.C., the public space permitting process is more rigorous than in other jurisdictions, so the design team collaborated closely with DDOT staff to align on the vision. This required multiple revisions to the landscape and grading design, while also working to meet the architect’s targeted slab elevations to minimize construction costs and project impacts.
Overcoming Challenges
Bohler DC faced significant grading challenges when dry utility vaults were proposed in the loading dock. These long vaults, built on a single plane, required careful planning prevent potential flooding in the alley and protect the loading dock.
During construction, an unforeseen challenge arose with a combined sewer pipe under F Street, dating back to 1873. While the sanitary main had always been indicated on the plans, it’s common for discrepancies to surface once construction begins and DC Water inspectors are on-site. In this instance, the inspector expressed concerns about the public space design being built over the pipe, citing potential risks to its structural integrity.
To resolve this, DPR conducted CCTV inspections and confirmed there were no active connections to the main. Afterward, the team needed to complete an approved plan revision during construction. “Only then were we allowed to abandon the main using flowable fill and proceed with the public space design above it,” says Bohler DC Project Manager Cameron Mavity.
“In addition, the existing Truist Bank next door remained operational throughout the construction process,” said Assistant Project Manager Matthew Koop. “The building is extremely old and required extensive coordination with DPR to support the bank building during construction.”
Other challenges such as asbestos, uneven floor slabs—which required extensive coordination with the architects to align with their grading plans—and misaligned columns were resolved using virtual design and construction technology. Prefabricated facade panels were also used to manage space limitations, ensuring access to the building’s alleyway and garage was maintained during construction.
Promoting Sustainability
The project’s sustainability features included a green roof, stormwater management systems that reduced water usage by 40%, and high-performance glazing designed to cut energy consumption by 20%. The construction team also recycled 75% of the 10,000 tons of waste. Bohler DC handled the stormwater calculations and documentation to secure the LEED stormwater credit, with the extensive green roof helping to meet DOEE regulations and LEED requirements.
Learn more about this award-winning project here.
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