Grouting Repair of Seawall and Revetment, Dana Point Harbor, California

Located at the westerly end of Dana Point Harbor, the Ocean Institute annually educates over 78,000 children through "immersion" expeditions into the wonders of the marine environment. A long awaited expansion of the facilities was begun in early 2001, to create the Ocean Education Center. This new waterfront campus is a 3,066 m² working marine research station, intended to maximize student participation in the learning process. Remedial grading for construction of the campus expansion involved removal and recompaction of old fill soils, immediately inland of the adjacent seawall and revetment. Excavation procedures included a shoring wall for protection of the seawall during soil removals. A sudden breach in the shoring system during a high-tide event flooded the construction excavation with over 10,000 m³ of seawater. Local erosion during this event resulted in subsidence of the revetment and a voided condition in the vicinity of the breach, leaving an approximately 8-m section of the seawall foundation unsupported. Consequently, repair of the breach was essential for construction to proceed. The repair process involved application of four discrete grouting techniques. Macroscopic voids were filled with a bentonite/cement slurry grout in the immediate vicinity of the shoring wall. Limited-mobility displacement grouting was used to compensate for local soil loss and to supplement inbound support of the revetment. Gravel was then packed beneath the seawall behind a bulkhead, and permeated with a Type-III cement grout. Smaller voids beneath the seawall were grouted with a fly ash/cement mix. The water was then successfully pumped from the excavation, and construction of the campus was able to resume. The Institute's Ocean Education Center opened in October 2002.