Characterization of Sediment at the Gorge Dam, Cuyahoga River Area of Concern, Akron, OH

摘要

Background/Objectives. The Gorge Dam, located on the Cuyahoga River between Akronand Cuyahoga Falls, OH, was identified in the Ohio 2008 Integrated Water QualityMonitoring and Assessment Report as a significant contributor to non-attainment of theState’s water quality standards due to habitat alteration and hydraulic modification (OhioEPA, 2008). GLNPO is working with the Ohio EPA to provide information that is criticalin the evaluation of the removal of the dam. Under the Great Lakes Legacy Act program,GLNPO completed a two-phase site characterization to determine the nature and extentof chemical contamination in the sediments upstream of the Gorge Dam with supportfrom Battelle. The objective of Phase 1, which was conducted in September 2009, was tocollect sufficient sediment physical and chemical data to estimate the prevalence ofchemicals of interest (COI) and the spatial variability of concentrations in those COI atthe site. The Phase 2 objectives which were to finalize the characterization of the natureand extent of COI and determine sediment thickness within the Cuyahoga River GorgeDam project area.Approach. Spatial correlation information obtained from historical data and Phase 1 resultswere used to develop a comprehensive but efficient sampling design. A blockkriging analysis was performed based on semivariogram models derived to determine theamount of sampling required to sufficiently characterize the spatial distribution of contaminantsin the investigative area. The combined Phase 1 and Phase 2 sampling strategyresulted in 50 discrete sample stations - 28 locations in Phase 1 and 22 locations inPhase 2. At each location, full-length (to refusal) sediment cores were attempted with vibracoreor push core methods. Refusal was not achieved at some locations due to variouscauses. A statistical approach was also utilized to determine the number of poling locations(N=181) needed to accurately (95% CI) determine sediment thickness, which wasthen used to calculate the total sediment volume within the targeted stretch of the CuyahogaRiver.Results. All COI were screened for potential adverse environmental effects using consensus-based probable effect concentration levels (PEC; MacDonald et al., 2000). Threecontaminants: cadmium, lead, and total PAHs, exceeded their PEC levels in >50% of thesamples. Interestingly, there were no notable hot spots either horizontally or verticallywithin study area sediments. However, statistical data summaries determined that, in general,contaminant concentrations were lower in the bend of the river by the Front StreetBridge and were demonstrated using three dimensional graphic displays. Site data indi