Apparatus for maintenance of a seawall comprises a plurality of anchoring members for being introduced through the seawall, a single retaining member for being secured on ends of the anchoring members which extend from a water facing side of the seawall, and a plurality of securing members for securing the retaining member on the ends of the anchoring members to tension the anchoring members and apply compressive force against the seawall. Another apparatus for maintenance of a seawall includes a retaining member having a rearward face beyond which the securing member and the end of the anchoring member do not protrude when installed on a seawall. An anchoring device installation system and method involves the use of a rail fixated to a floor at the bottom of a body of water on the water facing side of the seawall to guide formation of a passage in the seawall and the introduction of an anchoring member through the passage at preselected vertical and lateral angles.