Flood Mitigation in Historic Douglass Cemetery
Douglass Memorial Cemetery was established in 1895 as a segregated, nondenominational African American cemetery and it currently experiences frequent flooding which threatens the preservation of this historic burial ground. The City of Alexandria has engaged a team of engineers and archaeologists to evaluate the cause of the flooding and to develop solutions that are respectful to the sensitive nature of the site. Through examination of historic plans, careful site investigations and observations during intense storm events, it was determined that flooding is due to inadequate capacity of the existing stormwater infrastructure, poor surface drainage and new development areas that discharge to the stormwater drainage system in the cemetery.
To mitigate the flooding in this area, a multidisciplinary team has worked closely with the city and the Douglass Cemetery Descendant Advisory Group to develop plans to replace the existing stormwater conveyance system adjacent to and within the cemetery and to carefully regrade areas of the cemetery that have settled over time due to recurring inundation. The sensitivity of the site and the proximity of historic burial areas to the existing stormwater infrastructure and restoration area presents numerous technical and non-technical challenges.
The rehabilitation of infrastructure near historically sensitive areas poses various questions:
How can impacts to sensitive resources be limited? Can piped stormwater be rerouted to avoid sensitive areas? What will it cost for installation and for maintenance? How can these flooding issues be avoided in the future?
Both the answers and the process of investigation from this project are likely of value to others considering historically sensitive projects and this presentation will include a discussion of the following:
- Overview of the site constraints and historical resources challenges,
- Summary of the drainage analysis and physical site investigations performed,
- Design solutions, maintenance and preservation considerations and project costs.
