To the Acres go the spoils

Four Geo-Tubes hold what used to be at the bottom of Henlopen Acres' marina. Water is slowly seeping out of the bags, filled with material dredged from the marina. BY RYAN MAVITY
December 12, 2012

No, whales have not washed up at the Henlopen Acres marina; it’s just what used to be at the bottom of the marina.

The huge black, Hefty-bag looking things lying in rows along the marina are known as Geo-Tubes, a dewatering system that holds the spoils from the bottom of the marina and slowly allows water to drain out.

The town approved the $200,000 dredging of the marina this summer, and contractor Precision Marine Construction began the project in mid-October, Town Manager Thomas Roth said.

Precision Marine owner Rob Whitford said dredging was completed earlier this month with the dredged material now sitting in four large bags, 200-feet long and 60-feet wide. When blown up, they can be filled 7 feet deep with spoils.

Whitford said water slowly sweats out of the bags, which act as a filtration system that is designed to keep solids in and allow water out. Small trenches were cut around the bags to direct the water back into marina. Once the water is out, the spoils will harden, like a cake, he said.

The bags will then be unzipped and a hydraulic excavator will be brought in to lift the material out of the bags and onto dump trucks, where they will be hauled to an agricultural site on Route 16 east of Milton. Whitford said the material from the bags would be used both as backfill and fertilizer.

Precision Marine did the same sort of job for North Shores’ marina earlier this year. Roth said the bags would be on-site until May.