Delay in Dredging Silver Lake

Silver Lake dredging likely to be delayed

DNREC considers plan to use Geotube technology

By Ryan Mavity,  Cape  Gazette

Ryan  Mavity Photo

DREDGING THE WEST END of Rehoboth Beach's Silver Lake has been delayed as state officials try to nail down a staging area for the $300,000 project. Rehoboth Elementary School property is a likely choice, but that would push the start date un­til next summer.

Plans to dredge Silver Lake in Rehoboth Beach are moving for­ward, but officials say the choice of dredging equipment could de­lay the project until next sum­mer.

Mayor Sam Cooper said the Department of Natural Re­sources and Environmental Con­trol has approached Rehoboth Elementary School officials, seeking to use school property as a base of operations. Original­ly, plans called for basing the project on land at Silver Lake Park, but Chuck Williams, proj­ect manager of the department’s Shoreline and Waterway Man­agement Section, said that's no longer the case.

Cooper said state environmen­tal officials are considering using Geotube technology to store dredge spoils. It's a technology being used in dredging projects in Henlopen Acres and North Shores, in which sediment from the lake is pumped into a bag that filters sediment and sludge as water slowly drains out of the tube. The spoils are then re­moved for use as farm fertilizer.

Williams said the bags are 100 feet long and 35 feet wide; each bag holds 420 cubic yards of spoils.

Cooper said if the state decides to use Geotubes, it would delay the project until summer, when children are not using the school property.

Williams said the department is still considering the choice of dredge equipment. One factor is city efforts to protect the lake us­ing vegetative buffers. Williams said the department initially con­sidered staging a mechanical dredge in Silver Lake Park. But because new vegetation has been planted, it is not feasible to re­move the plants and restore them afterward, Williams said.

Officials are now considering a hydraulic dredge, using Geotube for the spoils. Mechanical dredges are typically placed on the shoreline, whereas hydraulic dredges float on the water and pump the spoils to an offsite lo­cation. Cooper said the school is the most logical base of opera­tions, because Silver Lake Park is too small to place the bags.

Williams said using a hy­draulic dredge and Geotube is a much cleaner operation than mechanical dredging.

The bags are designed not only to filter the spoils, but to also treat the water so that it is clean when released back into the lake, he said.

DNREC officials have contact­ed Cape Henlopen School Dis­trict about using the school, Williams said; initial talks have been positive, although no deci­sion has been made.

The cost of the project has been estimated at $300,000. At least $200,000 will come from the state's 21st Century Fund, a section of the state budget that funds long-term infrastructure projects.

Williams said the state will likely look for the remaining $100,000 once it knows whether the school site is available.

Cooper said city taxpayers are also expected to contribute to the project.