NSA Annapolis Shoreline

Carr Creek runs through Naval Support Activity Annapolis at Greenbury Point, an active military installation in the North Severn Area of the U.S. Naval Academy. Along both sides of the creek, steep forested banks about 10 to 12 feet high were eroding, with an undercut toe sending sediment into the creek and threatening trees and cultural resources regulated by the Maryland Historical Trust. There was no existing marsh within the work area to buffer the shore.

The U.S. Navy funded a living shoreline through a cooperative agreement with NAVFAC Washington. The Alliance for the Chesapeake Bay held the prime agreement and managed the project, Mariner Science & Exploration served as technical lead, and Sustainable Science worked as engineering subconsultant from the kickoff meeting in October 2021 through the as-built deliverables in July 2024. The goals were to stabilize four reaches (E, E1, G, and P), arrest sediment delivery to Carr Creek, and protect existing trees and cultural resources, with no grading of the slopes and minimal disturbance.

Sustainable Science started with a historical data review and a conceptual layout drawn from LiDAR and orthoimagery, then completed a topographic and bathymetric survey with substrate characterization alongside a tree survey, wetland delineation, utility location, and GIS base mapping. A wind and wave analysis, with the longest fetch of roughly two miles, and a tidal elevation analysis set the sill location and elevation, and the concept accounted for projected sea level rise.

The design is a low-profile hardwood log sill: logs of at least 16 inches in diameter with their tops set at mean high water, secured with rebar or all-thread, with branch packing to fill the undercut toe. A band of sand fill 10 feet wide sits behind the sills, broken by 10-foot vent openings, and extends no more than 11.1 feet channelward of mean high water. Low marsh of Spartina alterniflora and high marsh of Spartina patens, Panicum virgatum, and Panicum amarum are planted in the fill, with upland seed mixes and replacement trees at a one-to-one ratio for any trees removed. The permitted design called for 498 linear feet of sill, 200 cubic yards of sand, and approximately 4,095 square feet of marsh.

Sustainable Science prepared the 12-sheet construction plan set with the erosion and sediment control design, limits of disturbance, and access and staging on mulched haul roads and timber mats. Through the Navy 30 percent and 60 percent reviews, the firm tightened the limits of disturbance near historic sites and labeled the trees to be removed so that trees cleared for access could be reused as sill logs.

Mariner Science & Exploration led the joint permit application and coordination with the Maryland Department of the Environment and the U.S. Army Corps of Engineers, while Sustainable Science prepared the application plan set and led the erosion and sediment control permitting with MDE. The MDE Tidal Wetlands Division issued General Tidal Wetlands License 23-GL-0208 in September 2023, with federal authorization under the Maryland State Programmatic General Permit and a finding of consistency with the Coastal Zone Management Program. MDE approved the sediment and stormwater concept in August 2023 and issued final approval in January 2024, finding no stormwater management requirements for the project. The site lies within the Chesapeake Bay Critical Area and partly within the FEMA 100-year floodplain.

The team also obtained a Navy dig permit and an accident prevention plan, and coordinated on cultural resources and essential fish habitat. The Alliance for the Chesapeake Bay handled base access and approval routing with NAVFAC Washington and NSA Annapolis. Sustainable Science’s construction-phase scope, first limited to Reaches E1 and E, grew to cover all four reaches by March 2023.

Coastal Construction Services built the project in 2024. After the pre-construction meeting and site walk in March, Sustainable Science staked the work and set survey control. When the Navy installed a gate at the planned construction entrance, the firm redlined the erosion and sediment control layout, moving the entrance to the end of an existing gravel road and shrinking the stockpile area, and MDE accepted the revision within days. The access path was flagged around trees, and the initial clearing was mostly briars.

Work began in mid-April. By mid-May the first sand and stone had been delivered and log sills were in at Reaches E and E1, with G in progress; the east side went first, then Reach P on the west side through its own stone construction entrance. Sustainable Science made site visits, answered contractor questions, issued an interim punch list, and confirmed in a June inspection that the logs, vents, and sand fill matched the plans. Planting finished at the end of June, with the share of low marsh increased to match the observed high tide, and goose fencing went up to protect the Spartina. By mid-July, mulch covered the eastern haul road, four replacement trees had been planted for the two removed during construction, and the stockpile areas on both sides of the creek had been removed and stabilized. Mariner Science & Exploration provided construction oversight and inspection.

The project stabilized 607 linear feet of shoreline across the four reaches, placed 200 cubic yards of sand fill, and planted 4,095 square feet of new low and high marsh. The completed work was surveyed in June 2024, and Sustainable Science delivered the stamped as-built plan in July 2024, with CAD and GIS shapefiles of the sill, wetland, and topography in the Navy’s GIS format.

The tidal wetlands license requires 85 percent native cover for three consecutive years and annual marsh monitoring reports through September 2028, a five-year monitoring period. By early August 2024 the marsh vegetation was developing, the replacement trees were doing well, and the haul roads and stockpile areas were stable.

Installed about 607 LF of living shoreline along Carr Creek

Planted approximately 4,095 SF of marsh vegetation

Placed 200 CY of sand fill across four reaches

Secured MDE tidal wetlands license 23-GL-0208

Completed as-built survey and GIS deliverables

Planted four replacement trees, net two bonus