Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/853705
Bill Langer is a consulting research geologist who spent 41 years with the U.S. Geological Survey before starting his own business. He can be reached at Bill_Langer@hotmail.com CARVED IN STONE 32 AGGREGATES MANAGER / August 2017 W hen I was a kid, my family spent summers — and some holidays — at the Jersey shore. During early March 1962, a nor'easter, called the Ash Wednesday Storm, laid waste to New Jersey re- sort towns from Bay Head to Cape May. We went to the shore the following spring. The U.S. Army Corps of Engineers had begun an emergency beach-replenishment project to restore the damage on the storm-ravaged coast. I remember walk- ing on the beach with my dad. I was 17. There was a dredge off shore pumping a water-sand slurry through large pipes onto the beach. As the water drained off, heavy equipment moved and shaped the sand into dunes and a new beach. We were witnessing a tiny part of that massive restoration project. My dad said, "Time will tell." He told me that wave after wave slowly, but surely, eats away at the beach, and it was only a matter of time until another event like the Ash Wednesday storm would come along. (Hurricane Sandy comes to mind.) He predicted we would see more and more dredges spewing sand on the beaches. Beach replenishment, or beach nourishment as it is called today, is the subject of serious debate in many coastal areas around the world, not just the Jersey shore. Many people question if beach nourishment is economically sustainable, environ- mentally conscious, and sound engineering practice. However, other viable methods of beach protection are not apparent, and it is unlikely that multimillion dollar homes and billions of tourism dollars will be allowed to be washed away into the ocean. Therefore, general opinion seems to be that, al- though beach nourishment may not be an ideal solution, it is the best solution we have at hand. Most beach nourishment projects have 50-year life cycles. Furthermore, it is likely that flooding and beach erosion will worsen over time due to rising sea levels and increased intensity of storms associated with climate change. Unless there is a drastic change in the approach to beach protection, massive amounts of sand will be required to maintain beaches during "normal" years and for restoration after major storms. Right now, most of the sand is obtained from the continental shelf; a gently sloping nearly flat plain that extends offshore from the coastline seaward about 80 to 90 miles where it is about 300 feet deep. Beyond that is the continental slope and the ocean floor. There are mounds and ridges of sand on the continental shelf that are remnants of barrier islands that existed during the Ice Age when sea level was lower. These features are prime targets for beach nourishment. They are also home to large schools of fish and other sea life, and fishermen are concerned over their use for beach nourishment. That, coupled with iso- lated sand shortages creates pressure to look elsewhere for sand. Take, for example, a beach near Miami, Fla. They are running out of off-shore sand for beach nourishment, so sand is be- ing trucked to the beach from an on-shore sand operation about 100 miles away. Ironically, the sand comes from a deposit that was a beach in the geologic past when the sea was higher than today. My dad had it right about seeing more dredges in his lifetime and mine, but someday in the future, my grandkids or their grandkids may see dredges being replaced by fleets of trucks hauling sand to the beach from onshore sources. Time will tell. AM Sand has many environmental uses, but here is one that may not have come to mind. The Sand and the Sea While beach nourishment often involves dredging sand off shore and pumping it in, some areas are running out of off-shore sand and trucking it in from on-shore operations.