Carolina Beach Lake Dredging Project Town of Carolina Beach, NC & SEGi Town of Carolina Beach

Location Carolina Beach Lake is located approximately 1.2 miles south of the Carolina Beach Town Hall and just south of Atlantic Avenue

Historical Background The lake is a remnant salt marsh, lagoon that became isolated long before development of the island.

1949

1956

1998

2006

2010

2013

 Approximate Area = 11.5 Acres (500,940 SF)  Water depth average is approximately 18” deep  Majority of the feature is within the AE Flood Zone  Perimeter of the lake is maintained grass  Elevation is 0’ – 2’ above MSL  The Lake is classified as Watershed III (moderately developed)* (These waters are also protected for Class C uses)  The features is not tidally influenced  The lake received a Jurisdictional Determination on 4/13/12 and was issued under USACE Action ID SAW * Has been corrected since the submittal of the Scoping Meeting request form. Physical Characteristics of Carolina Beach Lake

Carolina Beach Lake Watershed

2013 Illustrating the sediment accumulation that has taken place:

Current Photos

FEMA Flood Zone Mapping AE Flood Zone VE Flood Zone 0.2% Annual Chance

New Hanover County GIS Topographic Map

Purpose and Need  Purpose – To increase the depth of the lake, for the purpose of reducing flooding of the surrounding residential and commercial structures.  Need – To excavate / Dredge approximately 6’ - 10’ of sediment (muck) from the bottom of the Lake. Excavation will not take place within 5’ off the bank.

2010 Flood Event

2010 Flood Event (Cont.)

Potential Removal Methods  Pump the dredged material to the old equalization basin  Excavate and haul slurry sediment to the old equalization basin  Excavate and haul cake like material to the old equalization basin

Equalization Basin

Equalization Basin (Cont.)

Sediment Sampling and Water Table Assessment  Assessment performed by S&EC Consultants, PA  No predetermined set of analytical procedures for this type of work  Soil samples were analyzed RCRA metals and for semi-volatile organic compounds  The results of the soil sampling did not produce evidence of any gross contamination of RCRA metals in the samples.  Bis-phthalate was the only semi-volatile compound detected, but measured well below the regulatory maximum for that compound.  Analysis of two shallow water table borings was performed to determine the soil morphology and identify seasonal high water table

Sediment Sampling and Water Table Assessment (Cont.)  Based on the soil borings, each location had signs of disturbed soil or fill material on top of the old natural material  The old buried “root matt” was noted at 32” below the surface  Seasonal water table depths were recorded at 1.85’ and 2.23’ below the surface at TW-1 and TW-2 respectively.

Questions and comments welcome!!