The East Hagatna Shoreline Protection Project is currently in the feasibility study phase. The study area is located on the west central coast of Guam between the villages of Asan and Tamuning. This study is authorized by Section 14 of the Flood Control Act of 1946, as amended. The Government of Guam, represented by the Bureau of Statistics and Plans (BSP) and the Department of Public Works (DPW) is the local non-federal sponsor. A feasibility cost share agreement (FCSA) was executed on 18 August 2021.
The study area is located north of downtown Hagatna, adjacent to Marine Corps Drive (Highway 1) along approximately 2,100 feet of Trinchera Beach at Hagatna Bay. There is a significant shoreline erosion problem at Hagatna Bay that has been ongoing for many years. A seawall constructed in the 1990s, intended to mitigate for this erosion, is being undercut by erosion and is on the verge of collapse. Marine Corps Drive is the primary roadway connecting Andersen Air Force base and Navy Base Guam as well as the primary access to many local villages, including downtown Hagatna, the capitol and major cultural center of Guam. Damage to the highway and utilities would result in major traffic delays, economic loss to businesses in the Hagatna area and disruption of public services. Additionally, the bay is used for recreational activities by both residents and tourists.
The Tentatively Selected Plan (TSP) consists of a 2,100 linear feet revetment to replace the existing seawall. This design involves the removal and replacement of 2,100 ft of existing seawall with revetment. The revetment would consist of compacted fill as the foundation and base grade, a geotextile filter fabric, a double layer of underlayer stone, a double layer of armor stone, and anchoring by an oversized toe stone. Depending on the cost and availability of local stone, use of pre-cast concrete armor units (tribar) may be considered. This design will meet USACE coastal engineering criteria for expected design life and adaptability to relative sea level change (RSLC). The TSP is the least cost alternative with a project first cost estimate of $11 million.