Reports
Masonville Dredged Material Containment Facility exterior sedimentary environment baseline study 2008
2009, Hill, J.M., Van Ryswick, S., and Wells, D.V.
File Reports, Coastal and Estuarine Geology, File Report 2009-06
Executive Summary
The Masonville Dredged Material Containment Facility (DMCF) is located in Baltimore Harbor and is currently in the initial stages of construction that began in September, 2007. The site is an upland disposal site anchored on land, and will have a diked containment area projecting into the Patapsco River. The site is designed to accept dredged material from Baltimore Harbor that would in the past, have been be sent to the Hart-Miller Island DMCF, which will cease to accept dredged material at the end of 2009.
This is the third year of exterior monitoring at Masonville DMCF. The purpose of the monitoring is to document baseline conditions prior to construction of the containment facility. The baseline data will be used to monitor the effects of the construction and operation of the facility. Ten (10) sites, the same that were sampled in 2006 and 2007, were re-sampled in 2008. Nine (9) monitoring sites were adjacent to the footprint of the dike and one (1) additional site was 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 sediment data. The samples were collected September 16 and 17, 2008. Samples consisted of undisturbed sediments collected at the sediment-water interface.
The data showed:
- There were only small changes from the 2006 and 2007 monitoring year conditions.
- Sediments are fine grained. The Masonville DMCF extends further into the Harbor and has a slightly lower average sand content and higher silt content when compared to sites closer to the mouth of the Harbor. The clay content is consistent with previous studies in Baltimore Harbor.
- Based on the total nitrogen (N) content of the sediment, the input of organic matter from primary production is consistent with the rest of Baltimore Harbor, and there is a lower terrigenous carbon (C) input than towards the mouth of the Harbor.
- The sulfur (S) to carbon ratio indicates that the area is less disturbed than other areas in the Harbor, or has a lower sedimentation rate.
- The average for all of the metals in the study area showed a slightly lower enrichment this year in comparison to last year and more similar to the 2006 monitoring year.
- Cadmium (Cd), nickel (Ni), manganese (Mn) and iron (Fe) are within background levels found for the Northern Chesapeake Bay.
- Trace metals in the study areas follow the patterns seen in the 1994 - 1997 Baltimore Harbor study. There is a source of chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) north and west of the Masonville DMCF site. All of the statistically enriched metals diminished to background levels south of the site. This is in contrast to 2007 where Cu and Pb are enriched throughout the entire study area.
- The reference site sample is physically similar to samples from the monitoring sites, but it is more remote than the other samples, and in the area with the most enriched metals content. The reference site helps provide spatial coverage to define the external source of the metals, but may not be a good gauge to measure changes due to construction and operation of a dredged material containment site.
Generally, the 2008 monitoring results showed the sediments around the DMCF were slightly coarser; accounting for the slightly lower metal contents, though comparable to the previous monitoring years.
