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 under 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 (ft) of Trinchera Beach at Hagatna Bay. Marine Corps Drive is the primary roadway connecting Andersen Air Force base and Naval Base Guam as well as the primary access to many local villages along the Western coast of Guam, including downtown Hagatna, the capitol and major cultural center of Guam. 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. Damage to the highway 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 the construction of a 1,630 linear-foot (lf) precast concrete seawall to replace the most critically damaged sections of the existing seawall at Trinchera Beach. The precast concrete seawall design acts as a cantilever retaining wall that utilizes the weight of backfilled soil to provide resistance to lateral earth pressures. Installation of the precast concrete panel wall would consist of excavating the existing soils to the limestone shelf and placing the precast concrete panels. After construction, the excavated area would be regraded to the elevation of the existing ground surface. This design has a top elevation of 8.9-ft above MSL, a crest width of 1-ft and a base that is 7-ft wide, with the total disturbed area being approximately 20- ft due to excavation and backfill of the existing soils. A splash apron composed of formed concrete over a gravel fill behind the crest of the structure is included to provide scour protection and tie the structure to the existing ground. 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 $16.2 million.

A previous version of the Draft Integrated Feasibility Report and Environmental Assessment (IFR/EA) identified a revetment as the tentatively selected plan. Based on engineering comments received on the 2023 Draft IFR/EA, USACE revised its designs and cost estimates and identified a precast concrete seawall as the TSP. To make sure the public is informed of the change and has an opportunity to comment on the new plan, the USACE and Guam BSP are releasing the updated Draft IFR/EA for public review again.