Page 22 - Port of Baltimore - May/June 2017

PORT ENVIRONMENT
questions and dispersed uncertainty. The creation of a new framework from MDE allows the material to be screened and then used with appropriate controls, such as a clean cap and protecting groundwater.
“We’ve each done a lot of legwork and education within our own agencies,” Weiss said.
A YouTube video explaining the initiative is available at www.youtube.com/ watch?v=yiVhs5P0Zjg.
The dredged material shows promise for use in other forms too. A pilot project in Virginia several years ago used bay channel-dredged material to grow barley. It worked well, but the cost of transporting the material to Virginia was prohibitive. The State Highway Administration is testing several blends to see if MDOT MPA’s dredged material can be reused as engineered fill, borrow material and manufactured topsoil in roadway projects.
“Finding innovative ways to manage sediment removed from the shipping channels serving the Port of Baltimore is a priority for the MDOT MPA,” said its Director of Harbor Development Chris Correale. “With the development of MDE’s draft guidance document and technical screening criteria, there is now a clear path forward for making innovative reuse a reality, not just for the MDOT MPA but for the private sector and related industries throughout Maryland.
“While we have encountered challenges with the material at every turn, it doesn’t make it impossible,” Weiss noted, adding that industry increasingly has expressed interest in working
with the MDOT MPA to use the material. “What we have found is that it does have great potential.” 􏰀
From Recycled Concrete Aggregate to Oyster Reef
Maryland’s State Highway Administration funded a five-year, three-phase study to determine if recycled concrete aggregate (RCA) from highway projects could be safely used to create oyster reefs. Reefs once were made of oyster shells, but those shells are scarce due to the declining oyster population.
The study, conducted at
Morgan State University’s Patuxent Environmental & Aquatic Research Laboratory (PEARL) and its National Transportation Center, first did extensive tank testing, using water drawn from the Chesapeake Bay, to evaluate whether chemicals from the aggregate leached into the water. Researchers also evaluated oyster
growth and spat (baby oysters) survival in flow tanks, comparing traditional shell and a mixture of shell with RCA as a base material.
“Native oyster populations are at less than 1 percent of historic levels due to protozoan diseases, overharvesting and pollution,” said Kelton Clark, Director of PEARL. “This tremendous decline has dramatically changed the bay’s ecosystem and oyster industry. Individual oysters filter 4 to 34 liters of water per hour, removing sediments and pollutants. Historic oyster populations could filter the bay’s entire water every three or four days, but today that takes nearly a year.”
Initial results indicated that recycled aggregate reefs could work.
[20] The Port of Baltimore ■ May/June 2017
The state is determining whether recycled concrete aggregate from highway projects can be used to create oyster reefs. Oyster growth and survival rates were compared in tanks. (Bottom right) Dr. Kelton Clark (left) works with a local waterman for oyster restoration.