Neponset River Sediment study… • The restoration of anadromous fish to the Neponset River has been the subject of a study by the US Army Corps of Engineers. • One of the findings is the presence of PCBs in the sediments impounded behind both the Baker Dam and Tilestone-Hollingsworth Dam. The sampling effort was limited, however, to one sample in each impoundment.
Cooperators … • Massachusetts Executive Office of Environmental Affairs • Massachusetts Department of Fisheries, Wildlife, and Environmental Law Enforcement • River Restore • U.S. Environmental Protection Agency • U.S. Geological Survey
Budget and timeline … • $284,910 • The project began July 2002 and is slated to end October 2003
Major players and their role … • U.S. Geological Survey • Robert Breault project chief • Jason Sorenson field sampling • Stacy Archfield field sampling • Andy Massey field sampling • Massachusetts Executive Office of Environmental Affairs • Karen Pelto River Restore Coordinator • Mike Merrill field sampling
Objectives… • Review existing data, conduct site reconnaissance, prepare quality assurance project plan • Measure water depths and sediment thickness • Assess sediment quality in the Neponset River • Determine specific sources of polychlorinated biphenyls
Scope … • The following samples and data collected throughout theNeponset River: • Water depth • Sediment thickness • Twenty surficial-sediment samples • Thirty-five sediment cores • Twenty-four PISCES deployed along the Neponset Riverand contents analyzed for PCB congeners
Braided Channel The study area… T&H Dam Baker Dam Mother Brook Paul’s Bridge
Water depths and sediment thicknessdata collection… • Water depth data were collected using an echo sounder and sub-meter accurateGPS (over 5,000 soundings). • Sediment thickness data were collected using a sub-bottom profiler and manual probing with a steel rod (over 110 manual measurements).
PCB Congener Samples…. • PISCES samplers were deployed and retrieved two weeks later at strategic points along the Neponset River. • Hexane was decanted and sent to AXYS analytical for congener analysis.
Sediment Sampling… • Twenty surfical sediment samples were collected randomly throughout the Neponset River. • Thirty-one sediment cores have been collected in three areas of the river (Baker and T&H Dam impoundments, and the Braided Channel.
Sediment Core Processing… • Cores were photographed and logged prior to homogenization. • Cores were composited in Teflon bags. Each bag was rinsed with methanol, 5-percent nitric acid, and DIW, in that order.
Sediment chemical analysis… • Surficial-sediment and core samples were sent to XRAL, laboratory for analysis of inorganic elements. • Surficial-sediment and core samples were sent to USEPA, Region I laboratory for analysis of organic compounds including, PCBs and Pesticides. • Surficial-sediment and core samples were sent to USGS, Kentucky Sediment Laboratory for grain-size analysis. • Core samples were sent to New England Testing Laboratory for MassEPH analysis.
Quality control … • A quality assurance project plan was approved for this project. • Quality control samples were sent to both laboratories including, • Duplicates • Performance evaluation samples purchased from theNational Institute of Standards and Technology (NIST) • Equipment “blanks” • Bathymetry and sediment thickness maps will be QA/QC’d once these maps are prepared by means of manual measurements in the field.
How will the physical data be analyzed and presented? • River channel morphology and the thickness of impounded sediments will be mapped using a combination of the triangular irregular network (TIN) data model and topogrid functions of ESRI’s ARC/INFO geographic information system (GIS) software (Environmental Research Institute Inc.). • The total volume of fine-grained bottom sediment behind each impoundment will also be determined using the TIN data model of ARC/INFO
How will the PCB data be analyzed and presented? • RMSD will be determined as the square root of the sum of squared differences between normalized congener concentrations in the two samples divided by the number of congener pairs compared. • RMDS = [S (A-B)2/ n]0.5 • Where: • A, B are normalized congener concentrations, in nanograms per sample • n is the number of congener pairs
Working hypothesis… • Former Lewis Chemical Company • 1940-1960 leather manufacturing • 1963-1983 Lewis Chemical Company • Hazardous waste • Collection • Transportation • Storage • Processing • Forced to terminate operations under a Court Order issued by DEP in 1983 Findings: • SOIL: PCBs (aroclor-1248) were detected in the soil samples (Environmental Strategies & Management, 2002) X Site of former Lewis Chemical Company
How will the chemical data be analyzed and presented? • The extent of contaminant enrichment in Surficial-sediment samples will be determine by comparing sediment chemistry to “background” concentrations of elements and organic compounds. • The potential for adverse biological affect by contaminated sediment will be determined using consensus-based freshwater sediment quality guidelines. • The potential for adverse health effects on humans from contaminated bottom sediment will be addressed using direct-contact, exposure-based soil concentration standards.
How will the findings be published? • A USGS Water-Resources Investigation Report is planned.