Contained Coastal Scour Protection
Coastline erosion has become an increasingly problematic issue, especially where infrastructure is affected. Engineers, Permitting Agencies, Municipalities and local communities wrestle with solutions that will meet performance needs, existing permit regulations, and budget restraints. A common coastal problem faced by communities around the world occurs when heavy wave action continues to erode existing coastline to the point infrastructure becomes endangered and/or is brought to failure. These problems make cause for transportation delays, loss of revenue for local businesses, and most importantly threat to public safety.
A series of solutions utilizing local materials (sand and stone) coupled with the superior engineering performance of containment of such materials in-place, can provide results that will satisfy engineering need and environmental mandate, while controlling costs and expediting construction time.
This was the case for an elevated roadway along the North Center Coastline in Old San Juan, Puerto Rico. The section of roadway is part of the main access road into Old San Juan, the oldest settlement within Puerto Rico. For a decade, heavy wave action caused severe damage to the area, eroding the toe of a 90 ft. tall, 2:1 slope supporting the highway PR25R. When a landslide occurred in the area in the Summer of 2015, it brought down several metric tons of sand and clay. In its path, it also took out a lane of the roadway and adjacent side-walk, frequented used by tourists, Government agency workers and local-residents, depositing it into the sea below.
A long-term solution was to support a new slope and protect it from future erosion at the toe.
The U.S. Army Corps of Engineers (Jacksonville District), Department of Natural Resources, Puerto Rico Highway Authority and local agencies approved the design for a two phase project consisting of a Marine Mattress (confined stone) base foundation, sand filled geo-containment tubes (confined sand) as a breakwater revetment core and a rock veneer cover to protect the newly constructed slope while awaiting the new phase of steel sheet piles for the support of the repaired and widened roadway and adjacent sidewalk.
This unique solution brought construction time and costs within budget and eliminated timely delays by holding the rock foundation and sand core breakwater in place during the construction phase during periodic storms (surge and waves) on the very exposed shoreline.