Reports
Cox Creek exterior sedimentary environment baseline study 2006
2007, Hill, J.M.
File Reports, Coastal and Estuarine Geology, File Report 2007-04
Executive Summary
The Cox Creek is a dredged material containment site located in Baltimore Harbor. The Cox Creek facility is a site which was in operation in the 1960’s through 1984, which has been reactivated. A limited amount of material was accepted in 2005. The site is an upland disposal site anchored to land, with a diked containment area projecting into the Harbor. Dredged material from Baltimore Harbor is the primary material designated to be placed in the site. Use of the site will prevent overboard disposal of dredged sediment and accept material that would in the past be sent to the Hart-Miller Island Containment Facility (HMI). HMI is to be closed at the end of 2009.
A total of 10 sites were sampled to establish a baseline to monitor the effects of reactivation and operation of the containment facility. Nine (9) monitoring sites adjacent to the area with 1 site designated as reference site. EA Engineering, Science and Technology (EA) collected the samples and the Maryland Geological Survey (MGS) was responsible for analyses and interpretation of the data. The samples were collected late September (9/19,20, 21,and 29) 2006. Samples consisted of undisturbed sediments collected at the sediment-water interface.
The data showed:
- Sediments are fine grained. The sediments have a slightly higher Sand content than sediments further into the Harbor. However the average Clay content for the area is ~20% , comparable to samples from previous studies in Baltimore Harbor.
- Based on the total N content of the sediment the area is consistent with the overall Harbor area with a consistent input of organic matter from primary production. However , the area around Cox Creek area has a higher terrigenous C input, being closer to the main stem of the Bay and other sources of non-reactive/terrigenous carbon.
- Cd, Mn, and Ni are within background levels found for the Northern Chesapeake Bay.
- Trace metals in the study area follow the general pattern seen in the 1994 - 1997 Baltimore Harbor study. However based on the enrichment distribution maps and elevated values greater than the in the previous study; the facility appears to be a source of Cr, Cu, Fe, Pb, and Zn to the external sedimentary environment.
- The reference site is not representative of the area. The site is physically different with a Sand content of 70%; the next highest Sand content is ~40% with the average sand content less than 20%. Additionally it has the highest relative metal content for most of the metals. The reference site helps provide spatial coverage to define the external source of the metals, but is not a good gauge to measure changes due to reactivation and operation of a dredge disposal site.
