Under 17th Street: archeology of the Potomac Park levee, a wharf and a sewer outlet

Digging beneath a busy Washington, D.C. street, beside some of the most visited park land in the capital, would not normally have been practical. Construction along 17th Street made it possible, and what it exposed was the infrastructure the Monumental Core was built over: a wharf built by enslaved labor, a canal lock keeper's house, a sewer outlet and tens of thousands of cubic yards of dumped fill. This summary follows part 2 of an NPS series on the archeology of the Monumental Core, written by Charles LeeDecker.

Why the digging was possible

Recent construction projects along 17th Street revealed a few archeological sites tied to landscapes that existed before the Monumental Core parklands were made. The largest was the Potomac Park Levee, where a levee closure structure crosses 17th Street into the Washington Monument Grounds and West Potomac Park. The site of main interest was the 17th Street Wharf, an important part of the city's historic infrastructure, built by slave labor and later a workplace that was predominantly African American. The wharf lies under pavement, flanked by heavily visited park land; fieldwork happened during construction, when traffic control and public safety measures were in place and heavy equipment was available for deep excavation.

The wharf: bottles and a lunchroom

One construction trench in the roadway held massive timbers possibly from the wharf's deck. In the same trench, deeply buried, artifact-rich layers held glass and ceramic vessels and food remains. Similar deposits occur at household sites elsewhere in the city, but here they seem to show drinks, medicine and food consumed in an industrial workplace, and some may be linked to a lunchroom run by Henry Hill. The most notable finds are more than 100 pieces of 19th-century-style stoneware bottles. Other finds include a stoneware master ink bottle, glass beer or mineral-water bottles, a wine or liquor bottle, fruit-jar fragments and lamp-globe pieces.

Stoneware bottles from the 17th Street Wharf site. NPS

Glass bottles from the wharf site: a "Salvation Oil" medicine bottle (left) and unmarked patent or prescription medicine bottles. NPS

Fill from the whole city

Test pits elsewhere in the levee zone held highly varied fill: late 19th-century household refuse and building debris, including whole beverage and medicine bottles, with ceramic fragments throughout. The variety shows that fill in the late 19th century was drawn from many sources, not just sediment dredged from nearby shipping channels. The Chief of Engineers' annual reports from the 1870s say local citizens and cartmen dumped great quantities of street sweepings, household refuse and construction debris on public land, along with material from grading Pennsylvania Avenue and from excavations for major public buildings. Contractors supplied tens of thousands of cubic yards, and anonymous citizens dumped single cartloads of cellar spoil, furnace ash and backyard trash.

The sewer outlet

The most impressive feature was the headwall of the sewer canal outlet where the B Street sewer emptied into the Potomac, which the article quotes Hains as calling "a grave error in sewage disposal". Partly exposed and dismantled for the levee structure, the Tiber Creek Sewer Outlet was a massive brick shaft five courses thick. Its headwall was about 40 feet long, with two shorter wingwalls on either side. The sewer portal had an arched, semi-elliptical opening of stones topped by a keystone dated 1880. The shaft was 23.5 feet wide inside, closely matching an 1892 city sewer map, and about 13 feet high by estimate. A small feeder line to the same network was documented along 17th Street during earlier work in President's Park.

Headwall of the sewer canal outlet that emptied into the Potomac River. Lockhouse B is in the background. NPS

Detail of the keystone from the sewer outlet. NPS

The canal lock keeper's house

A short sewer replacement along 17th Street let archeologists document two resources from the 1832 C&O Canal Extension. Reclaiming the Potomac Flats took millions of cubic yards of fill, which engulfed the wharf, the lock and the lower part of the lock keeper's house. When 17th Street was extended across the new land in 1902, it followed the wharf's alignment and partly crossed the abandoned house's footprint. Lockhouse B was moved out of the right-of-way to its present location in 1915. During the 2012 sewer replacement the original foundation was documented in an access shaft more than 12 feet below grade, and remains of Lock B were documented beneath Constitution Avenue. Both sites show the challenges and opportunities of archeology in a modern city, where early resources survive in settings that make fieldwork difficult.

Archeological documentation of the lock keeper's house foundation; the base of the original foundation is more than 12 feet below grade. NPS

Sources

• National Park Service, "Archeology in the Monumental Core: Part 2", from the series "History and Archeology of the District of Columbia Monumental Core", by Charles LeeDecker, who also wrote the 2013 monitoring report it draws on, prepared by The Louis Berger Group (https://www.nps.gov/articles/history-archeology-of-dc-monumental-core-part-2.htm); rewritten in hubnx's own words.