A.73 Terry Creek, GA

A.73.1 Summary

Environment:	Freshwater
Scale:	Full
Contaminants of Concern:	Toxaphene-Outfall Ditch Max: 2,600-30,000 ppm North Dupree Creek Max: 290 ppm Confluence Area Max: 110 ppm
Final Remedy:	A cable arm environmental clamshell bucket was used. Removed material was retained in drain beds for six months to dry. Dried contaminated sediment was sent off site to Savannah, Georgia, 78 miles.

 

A.73.2 Site Description

Three removal areas:

• Outfall Ditch
• North Dupree Creek area
• Confluence area

 

Year: 2000

Target Volume: 26,000 yd³

Actual Volume Removed: 35,148 yd³

A.73.3 Remedial Objectives

Mass removal of toxaphene:  target depth 1-8 ft in Outfall Ditch and 1-6 ft everywhere else.

A.73.4 Remedial Approach

A cable arm environmental clamshell bucket was used.

Three removal areas:

Outfall Ditch

North Dupree Creek area

Confluence area

A.73.5 Monitoring

Resuspension:

Sheet piling dike installed around perimeter of Outfall Mouth removal areas to minimize run-in of adjacent creek sediment due to required 5 ft excavation and to aid in controlling migration of sediment outside removal area.

Silt curtains for containment.

Air and water samples taken to ensure contamination did not disperse.

Residuals:

Technically no numerical goal numbers hit. Decided removal was adequate based on post-removal concentrations.

Post dredging concentrations:

Median: 4.5 ppm

Max: 2,700 ppm toxaphene

Sampling was done inside and outside of silt curtains to ensure resuspensionA renewed suspension of insoluble particles after they have been precipitated. measures were successful.

A.73.6 References

Agency for Toxic Substances & Disease Registry Public Health Assessment Terry Creek Dredge Spoil Areas/Hercules Outfall Site Brunswick, Glynn County, Georgia as updated Mar 2010. http://www.atsdr.cdc.gov/hac/pha/pha.asp?docid=1030&pg=1 (ATSDR).

USEPA Region 4: Superfund Terry Creek Dredge Spoil Area/Hercules Outfall as updated Jan 2012. http://www.epa.gov/region4/superfund/sites/npl/georgia/tcredrespoga.html.

Major Contaminated Sediment Sites Database; Sept. 2004 as updated 2008. http://www.smwg.org/MCSS_Database/MCSS_Database_Docs.html.

Publication Date: August 2014