Wilmington District Week in Review

District team works to repair dike breach on Eagle Island

Last week, we shared the good news about how well our Roanoke flood damage reduction project performed during the post-Ida rains. We are also happy to report that all our five reservoirs throughout the District enjoyed a re-charge from the rains. But there has been some bad news too.

The days-long rainfall that passed over the Atlantic East Coast last week brought supersaturated soils, along with strong winds and wave action to the Southeastern North Carolina coast line. One of the ill effects came to light last Sunday morning, November 16, when a serious breach was discovered in a dike on the Cape Fear River’s Eagle Island dredged material disposal area. The dike and spillway number one, where the break occurred, had been checked and found standing strong the previous evening. Some time during the night, it appears that water began seeping around the spillway drainage pipe within the dike fill, and the wood spillway structure, pipe, and dike discharged into the Brunswick River.

“All of the Eagle Island disposal areas receive inspection before a dredging project begins, so our folks had a good look at the dikes within the past month. Also, the dikes are routinely checked by contractor personnel and by workers from New Hanover and Brunswick Counties conducting insect control work on Eagle Island. We had no reason to anticipate a weakness at Spillway Number 1 prior to the incident,” said Bob Keistler, project manager for dredging in the Cape Fear River channel.

This 50-foot wide breach opened up in a dike on Eagle Island, a major Cape Fear River Channel dredged material disposal area on Saturday night, November 15.

Inspections have determined that about 26,000 cubic yards of material escaped, blanketing a marsh along the river with two to three feet of sediment. About 5.76 acres of marsh were affected. Fortunately, the dredged material that flowed out does not contain harmful levels of any contaminants.

The disposal area is an uninhabited island on the Brunswick County side of the Cape Fear River. It has three ‘cells’ or land areas, each surrounded by dikes. Dredged material that is unsuitable for placement on a sandy beach is pumped into the cells as watery slurry, and gradually ‘dewatered’ through evaporation and by drainage through spillways built into the earthen dikes that surround the cells. Cell one, where the breach occurred, was being used to receive dredged material from a contract to dredge the Anchorage Basin for the Wilmington Harbor Project. However, no dredging had occurred after the 9th of November, when Southern Dredging took a break to switch out dredges. “It appears the primary problem was the heavy and continuous rainfall,” said Keistler.

What is being done to address the problem?

• Actions to slow the discharge of material were taken immediately on Sunday the 16th, and on Wednesday, November 18th, ES&J Enterprises, Inc., an earth moving contractor with experience working on Eagle Island, set to work on the first of three task orders to accomplish repair and restoration. Their first task will be to put in place a coffer dam around the breach and stop all discharge of material
• Meanwhile, members of the District’s environmental staff have inspected the area along with officials from the NC Land Resources commission, the Coastal Area Management Authority (CAMA) and the NC Marine Fisheries commission. They have identified the extent and nature of the damage. With the agency input, the District is drafting a restoration plan which will be forwarded to the agencies for review over the next week. The plan will likely involve removal of the discharged material from the marsh area, but placement of that material is yet to be determined.
• After the coffer dam is in place ES&J will repair the dike. Other work will include completing the environmental restoration and clearing vegetation along the toe areas of the dike and around spillways to ease future inspections and reduce the possibility of like incidents in the future.

Have a question about this project? Contact Penny Schmitt at 910-251-4626.

Reservoirs refill during Ida rain event

Wilmington District’s reservoirs are going into the winter season in good shape, thanks to abundant rainfall brought by the remnants of Tropical Storm Ida. The chart below shows the elevations of our lake projects as of 8:00 a.m. on Thursday, November 19. The ‘guide curve’ is the desired level for each lake. As you can see, all our lakes are close to guide curve except for John H. Kerr, which is at 307.4 feet, and being brought back to guide curve by a moderate flood release of 20,000 cubic feet per second. The winter season is the time of year when we expect rainfalls to refill reservoirs that are often depleted by hot, dry summer weather and evaporation. For more information on Wilmington District reservoir operations, go to http://epec.saw.usace.army.mil/.

Click on Reservoir Name Below to go to Project Webpage:

	John H. Kerr	Philpott	Falls	B. Everett Jordan	W. Kerr Scott
0800 Elevation (ft-msl)	306.85	972.13	252.27	218.17	1029.82
Guide Curve (ft-msl)	296.23	971.50	251.50	216.00	1030.00
		Lake and Guide Curve Levels for the past 180 days

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