Reports
Centreville Dam Sediments Study Queen Anne's County, Maryland. Reconnaissance Survey of Sediments At Centreville Dam, Corsica River
2014, Van Ryswick, S., Sylvia, E.R.
File Reports, Coastal and Estuarine Geology, File Report 14-01
Executive Summary
In response to a request by American Rivers, Maryland Geological Survey (MGS) was contracted to study the sediments within the Centreville Dam impoundment located in Queen Anne’s County in the State of Maryland. The dam is located at the head of Gravel Run immediately to the southeast of the Rt. 213 bridge. The sediments required TCLP analysis to verify that the sediments meet the regulatory thresholds for TCLP metals for disposal at the Queen Anne's County landfill. Cores were collected at six locations to quantify the physical and chemical properties of the sediment, and to test for the presence of leachable metals above regulatory thresholds. The samples tested included sediments from five sites above the dam, a composite sample from these five sites, and a sample from a site below the dam for comparison. The fieldwork for this study occurred in September 2013.
This report focuses on Blairs Valley Lake in Washington County, Maryland and Franklin County, Pennsylvania. The lake is 22 acres and is located within Indian Springs Wildlife Management Area (WMA). Ten surficial sediment samples were collected throughout the lake and coordinates were stored using Real-Time Kinematic Global Positioning System (RTK GPS). Sediment at each site was described and sampled for analysis. The analysis includes physical properties, including bulk density and grain size, and elemental analysis.
The elemental concentrations of 10 surficial sediments followed similar spatial patterns when plotted by station. The concentrations of major elements Al, Fe, K and Mg as well as the concentrations of trace metals Cu, Ni, Pb and Zn were quite similar to each other in profile-plot, and generally similar to clay content. The concentrations of trace metals As and Cr differed slightly from these others, perhaps because they are less affected by sorption in these environmental conditions. Compared to the relative eco-toxicological screening levels LEL, most trace metals were above the conservative LEL, but only Fe was above the higher SEL in three samples. No eco-toxicological harm is anticipated. Compared to the relative crustal abundance via the use of Fe-normalized enrichment factors, the elements As, Cs, Hf, Pb and Sb are enriched. However, these elements are often encountered in high concentrations in clay-rich sedimentary rocks and the sediments derived from them. No anomalies or outliers were identified.
The 10 collected samples throughout Blairs Valley Lake were similar to sediments of other lakes nearby, including New Germany Lake and Deep Creek Lake. No abnormalities were found in regard to the physical or chemical properties of the bottom sediments of Blairs Valley Lake.
