Do fundo do mar... Sea bottom
Thursday, January 27, 2005
Beach work mindful of artifacts
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Delawareonline
By Molly Murray
January 27, 2005
Army Corps says it will tread lightly
The News Journal/SCOTT NATHAN
Workers load sand onto the beach at Laurel
Street in Rehoboth Beach on Monday as part
of the replenishment project.
State and federal officials are eagerly awaiting the broad expanses of sand that should be ready for beach-lovers in Rehoboth and Dewey this summer.
But they want to be sure that the price tag attached to building the beaches is not another hunk of Delaware's history.
The U.S. Army Corps of Engineers in February will start a $15 million beach replenishment project from Rehoboth south to Dewey, digging into the ocean bottom southeast of Indian River Inlet to suck up a million cubic yards of sand, which will then be piped onto the storm-ravaged shoreline.
But the corps and state officials said they will take special care to make sure the dredging gear does not ravage an underwater historical site, as a similar project did last fall in Lewes.
Taking sand from a site 200 feet off the Lewes shore, corps dredgers in September and October chewed into an underwater historical site - an old settlement or a shipwreck - and piped artifacts onto a beach near Roosevelt Inlet. Many items were shattered by the dredge and scattered along the sand for beachcombers to discover.
After the relics were spotted on the Lewes beach, state officials were unable to completely close the public beach. Two state legislators plan to propose a bill that would make it easier for the state to protect and quarantine historical sites discovered along the shore, including underwater locations in Delaware Bay or the Atlantic Ocean.
The bill from Rep. Joseph W. Booth, R-Georgetown, and Rep. Gerald W. Hocker, R-Ocean View, will provide authority for a 90-day moratorium on public access to historical sites that might be discovered in the future.
"The intent here is to prevent valuable archaeological sites from being disturbed before we have a chance to understand what we have and whether it needs to be further researched or protected," Booth said.
State scientists and corps officials hope that authority won't be necessary during the project that starts next month.
But they said it is difficult to say with any certainty what lies beneath the mud and sand on the bottom of the bay, or under the ocean along a continental shelf that has, over hundreds of thousands of years, intermittently been underwater or exposed.
A wealth of treasures
The sediment includes a wealth of treasures, ranging from the bones of mastodons to wrecks of sunken ships from Colonial days to Native American and early European settlements.
Kelvin Ramsey, a senior scientist and geologist with the Delaware Geological Survey, said the mud and sand found along Delaware's coastal plain also can be found off the coast, deep underwater.
That is clear from core samples taken from the sea floor, some with the silty deposits that might be found at the bottom of Delaware's Inland Bays, and others with fine sand that is common along the state's ocean beaches.
"That shoreline has moved back and forth in the last 10,000 to 12,000 years," he said.
Army Corps officials and state scientists have pored over images of the site where sand will be drawn for the Rehoboth-Dewey project - a sand bar south and east of the inlet.
Three sites protected
Underwater surveys revealed three potential "targets" - areas that might be shipwrecks or something significant because they contain enough metal to register on a magnetometer scan or are large enough to show up on side-scan sonar. Those sites have been marked and will be avoided by the dredge crews.
But Corps officials also thought they had a clear dredging site when they began the Lewes project, said Robert Dunn, the archaeologist with the corps' Philadelphia District.
The only hint of something amiss were two "sonar anomalies," he said, which experts thought were piles of rocks that had scattered off the nearby jetty. Corps officials do not typically dive on dredge sites because of the cost.
Dunn said the Rehoboth-Dewey dredging plan calls for avoiding all the identified "targets" and having the dredge work in narrow swaths across the bottom. If something is hit, the disturbance would be less significant than with a wider dredge path.
The corps also will not be using the type of dredging head used at Lewes, which is thought to have chopped up artifacts.
The dredge for the Rehoboth-Dewey Project will work like a giant vacuum, sucking sand and water from the bottom. The sand will be pumped to an offshore barge, transported north to the beaches and then pumped onto the shoreline.
In addition, a 1 1/2 -inch mesh screen will cover the suction end of the vacuum hose to keep out large objects.
That also should prevent the dredge from bringing ashore military ammunition that could be buried in the sand. The military used the beach south of Indian River Inlet more than three decades ago for target practice on drone airplanes that flew over the ocean.
Corps inspectors and the dredge crew also have been trained to better recognize broken glass, artifacts, arrowheads or even ancient elk bones that might end up on the beach with the sand.
Dunn has recommended inspectors who find bits of glass or unusual things to "pretend it's historical even if it may turn out to be a Budweiser bottle."
Looking to the summer
Officials said they expect their precautions will counter some of the risks in what is an important project for the state's tourism economy, and for protection from ocean flooding.
Once the beaches are built up from the 50 to 70 feet width they had eroded to, a tall dune to help against storm surges will be built, said Anthony P. Pratt, the state shoreline and waterway administrator.
Delaware environmental officials have for years been working to win federal funding for a beach repair project for Dewey-Rehoboth. Once the initial renourishment is done - with the corps absorbing most of the cost - the federal government also will maintain the beach every few years for the next 50 years.
Plastic piping for the project is already staged at the beach off Dagsworthy Avenue in Dewey Beach.
Pratt said the dredge crew will start in the center of Dewey Beach and work south, then move the pipe and start working north. The Dewey part of the project is expected to be complete in early April, he said.
The piping then will be moved north to Rehoboth Beach and staged in the center of the city's beach. The pumping will go from mid-beach south, then shift to the north, Pratt said.
Work is expected to be complete in Rehoboth by June 1, he said. The end result will be beaches five times as wide as last summer.
"This summer, we'll have the desert to cross," Pratt said.
Delawareonline
By Molly Murray
January 27, 2005
Army Corps says it will tread lightly
The News Journal/SCOTT NATHAN
Workers load sand onto the beach at Laurel
Street in Rehoboth Beach on Monday as part
of the replenishment project.
State and federal officials are eagerly awaiting the broad expanses of sand that should be ready for beach-lovers in Rehoboth and Dewey this summer.
But they want to be sure that the price tag attached to building the beaches is not another hunk of Delaware's history.
The U.S. Army Corps of Engineers in February will start a $15 million beach replenishment project from Rehoboth south to Dewey, digging into the ocean bottom southeast of Indian River Inlet to suck up a million cubic yards of sand, which will then be piped onto the storm-ravaged shoreline.
But the corps and state officials said they will take special care to make sure the dredging gear does not ravage an underwater historical site, as a similar project did last fall in Lewes.
Taking sand from a site 200 feet off the Lewes shore, corps dredgers in September and October chewed into an underwater historical site - an old settlement or a shipwreck - and piped artifacts onto a beach near Roosevelt Inlet. Many items were shattered by the dredge and scattered along the sand for beachcombers to discover.
After the relics were spotted on the Lewes beach, state officials were unable to completely close the public beach. Two state legislators plan to propose a bill that would make it easier for the state to protect and quarantine historical sites discovered along the shore, including underwater locations in Delaware Bay or the Atlantic Ocean.
The bill from Rep. Joseph W. Booth, R-Georgetown, and Rep. Gerald W. Hocker, R-Ocean View, will provide authority for a 90-day moratorium on public access to historical sites that might be discovered in the future.
"The intent here is to prevent valuable archaeological sites from being disturbed before we have a chance to understand what we have and whether it needs to be further researched or protected," Booth said.
State scientists and corps officials hope that authority won't be necessary during the project that starts next month.
But they said it is difficult to say with any certainty what lies beneath the mud and sand on the bottom of the bay, or under the ocean along a continental shelf that has, over hundreds of thousands of years, intermittently been underwater or exposed.
A wealth of treasures
The sediment includes a wealth of treasures, ranging from the bones of mastodons to wrecks of sunken ships from Colonial days to Native American and early European settlements.
Kelvin Ramsey, a senior scientist and geologist with the Delaware Geological Survey, said the mud and sand found along Delaware's coastal plain also can be found off the coast, deep underwater.
That is clear from core samples taken from the sea floor, some with the silty deposits that might be found at the bottom of Delaware's Inland Bays, and others with fine sand that is common along the state's ocean beaches.
"That shoreline has moved back and forth in the last 10,000 to 12,000 years," he said.
Army Corps officials and state scientists have pored over images of the site where sand will be drawn for the Rehoboth-Dewey project - a sand bar south and east of the inlet.
Three sites protected
Underwater surveys revealed three potential "targets" - areas that might be shipwrecks or something significant because they contain enough metal to register on a magnetometer scan or are large enough to show up on side-scan sonar. Those sites have been marked and will be avoided by the dredge crews.
But Corps officials also thought they had a clear dredging site when they began the Lewes project, said Robert Dunn, the archaeologist with the corps' Philadelphia District.
The only hint of something amiss were two "sonar anomalies," he said, which experts thought were piles of rocks that had scattered off the nearby jetty. Corps officials do not typically dive on dredge sites because of the cost.
Dunn said the Rehoboth-Dewey dredging plan calls for avoiding all the identified "targets" and having the dredge work in narrow swaths across the bottom. If something is hit, the disturbance would be less significant than with a wider dredge path.
The corps also will not be using the type of dredging head used at Lewes, which is thought to have chopped up artifacts.
The dredge for the Rehoboth-Dewey Project will work like a giant vacuum, sucking sand and water from the bottom. The sand will be pumped to an offshore barge, transported north to the beaches and then pumped onto the shoreline.
In addition, a 1 1/2 -inch mesh screen will cover the suction end of the vacuum hose to keep out large objects.
That also should prevent the dredge from bringing ashore military ammunition that could be buried in the sand. The military used the beach south of Indian River Inlet more than three decades ago for target practice on drone airplanes that flew over the ocean.
Corps inspectors and the dredge crew also have been trained to better recognize broken glass, artifacts, arrowheads or even ancient elk bones that might end up on the beach with the sand.
Dunn has recommended inspectors who find bits of glass or unusual things to "pretend it's historical even if it may turn out to be a Budweiser bottle."
Looking to the summer
Officials said they expect their precautions will counter some of the risks in what is an important project for the state's tourism economy, and for protection from ocean flooding.
Once the beaches are built up from the 50 to 70 feet width they had eroded to, a tall dune to help against storm surges will be built, said Anthony P. Pratt, the state shoreline and waterway administrator.
Delaware environmental officials have for years been working to win federal funding for a beach repair project for Dewey-Rehoboth. Once the initial renourishment is done - with the corps absorbing most of the cost - the federal government also will maintain the beach every few years for the next 50 years.
Plastic piping for the project is already staged at the beach off Dagsworthy Avenue in Dewey Beach.
Pratt said the dredge crew will start in the center of Dewey Beach and work south, then move the pipe and start working north. The Dewey part of the project is expected to be complete in early April, he said.
The piping then will be moved north to Rehoboth Beach and staged in the center of the city's beach. The pumping will go from mid-beach south, then shift to the north, Pratt said.
Work is expected to be complete in Rehoboth by June 1, he said. The end result will be beaches five times as wide as last summer.
"This summer, we'll have the desert to cross," Pratt said.
