Project Summary
Flooding has plagued King Street in the heart of downtown historic St. Augustine, Florida, for many years due to inadequate drainage systems and high tailwater conditions at the receiving waters. One drainage system discharging into the Matanzas River is also plagued with collapsed pipes and highly impervious drainage areas. These factors and others have contributed to significant drainage issues for this busy commercial and historic district, even during smaller storm events.
In anticipation of the reconstruction of King and Cathedral streets, along with the planned reconstruction of the intersection at the base of the Bridge of Lions, the Florida Department of Transportation (FDOT) retained Hanson to develop an outfall into the Matanzas River that was adequate to accept the future upgraded stormwater collection systems.
Hanson had previously designed a new stormwater collection system for King Street from Malaga Street to Avenida Menendez to a 90% level and was familiar with the conditions and ensuing demands. The outfall project was part of a plan to transfer ownership of King Street from FDOT to the city of St. Augustine.
Protecting history
King Street abuts historic properties, businesses and parks, which required significant coordination with FDOT, the city of St. Augustine and its Historic Architectural Review Board, the state historic preservation officer, other regulatory agencies and property owners. The condensed project involved installing a 54- to 60-inch drainage pipe system and a backflow prevention device starting from the intersection of Avenida Menendez and King Street and eventually penetrating the seawall along the Matanzas River. Most of the work occurred within Bayfront Park, a prominent landscaped area between the Bridge of Lions and the Municipal Marina.
A major objective of the project was to reconstruct any features demolished by the outfall installation to their original specifications. The impacts and subsequent reproduction included a concrete masonry wall, timber pergola, concrete columns, curb and gutter, sidewalks, lighting and asphalt pavement.
The work included installing a structure underground to stabilize the seawall due to the new outfall pipe severing the original anchor system that kept the wall in place. This involved driving sheet and king piles to significant depths while keeping in mind the nearby historic sites and minimizing disturbance to residents and visitors. The structure was critical for protecting the historic sites.
Buried treasure
The project team timed construction to minimize interruptions to the public, especially during high-profile events such as the world-renowned Nights of Lights, presented every year by the city of St. Augustine.
Because of the area's historic nature, an archaeologist was assigned to monitor any earth-moving operations during the construction of the outfall project. While digging at the intersection of King Street and Avenida Menendez, a work crew discovered a mostly intact, 28-foot-long, 19th-century maritime vessel 8 feet beneath the surface. FDOT retained SEARCH Inc., an archaeological firm with maritime specialists, to remove the mud and soil around the well-preserved vessel. After several days of documentation, the soggy, fragile, wooden planks and other found artifacts were placed in wet storage to protect them from the damaging air and moved off-site for further studies.
Construction of the outfall project was completed in March 2024.