Cleary project, the HDPE log anchors after 2 seasons. The HDPE logs allow sediments to pass through in both directions.
When the beach is building the HDPE logs help retain the sands, typically in summer. When the beach is receding the HDPE logs allows the built up sand to move out, only at a slower pace. In summer these HDPE logs are covered with sand, this photo was taken in January and the Hdpe logs are still retaining some of the summer sands, elsewhere on the beach it is mostly gone.