1. Introduction This section describes the sources of available data on which much of the performance standards is based. Completed dredging projects that provide information on upstream and downstream water column conditions, as well as on mass of contaminant removed, provide a basis for determining historical rates of loss and dredging-related recontamination. It was thought that dredging projects that have been completed or are currently in progress can provide practical information on resuspension issues. Information on water quality data, equipment used, monitoring techniques, etc. from these projects will give insight as how to develop the performance standards. For the resuspension standard, water column monitoring results available from other sites were used to complete an analysis of the case study data. The process used to gather relevant information from dredging sites and the information obtained are included herein. It is also important to review all information that exists for the Hudson River. Available data was used to assess the existing variability in the Hudson River water quality, and can be used to estimate the water column quality during and resulting from the dredging operation. Descriptions of the data sets available to perform this analysis are provided herein. 2. Case Studies Objective and Overview During completion of the Hudson River Feasibility Study (FS) and the associated Responsiveness Summary (RS), the GE dredging database, the USEPA website, and other online sources were investigated to identify dredging projects that were relevant and similar to that proposed for the Hudson River in size and complexity. The USEPA and State agencies were contacted to gather information for each dredging project. Information including but not limited to the type of dredging equipment utilized, contaminants of concern and associated concentrations, stabilization method, presence of odors, noise issues, problems encountered during dredging, effectiveness of silt/barriers, cleanup goal requirements (allowed residual), reduction rate in term of average concentration, average dredge equipment productivity, total volume to be removed, dredge season/period, average depth of cut, and method of monitoring for resuspension during dredging was gathered and tabulated. Final results were presented in Appendix A of the FS report and used to support statements and respond to comments on the FS report and white papers of the RS report. Sites including but not limited to New Bedford Harbor, Fox River, Saginaw River, St. Lawrence River, Commencement Bay, Cumberland Bay, Manistique River, Sheboygan River, and Grasse River were contacted. It was thought that additional information was needed to support the development of the performance standards. As a result, a dredging site survey (case study search) was conducted during preparation of the Hudson River performance standards to summarize remedial work conducted at various domestic dredging sites. Information related to specific removal operations, productivity, transport and sediment processing and handling, water quality monitoring and associated work plans, residual cleanup goals, post-dredge confirmation sampling, water quality Malcolm Pirnie/TAMS-Earth Tech 1 Public Review Draft – May 2003 Appendix: Case Studies of Environmental Engineering Performance Standards Dredging Projects modeling, and engineering contingency plans were collected from each of the sites surveyed when applicable and available. Case Study Tasks A general search was conducted on the Internet within each of the USEPA regional websites to identify recent dredging projects that may have been conducted since the completion of the Hudson River FS and RS reports. In addition, follow-up conversations were held with dredge site contacts established during the initial survey effort conducted during preparation of the Hudson River FS and RS. The following sources were researched to locate relevant information for dredge sites described in this document. Agencies/Organizations/Sources USEPA Regional Offices Michigan Department of Environmental Quality Wisconsin Department of Natural Resources Great Lakes National Program Office Fox River Group International Joint Commission -US and Canada Great Lakes 2000 Cleanup Fund Technical Journals GE Major Contaminated Sites Database The GE Major Contaminated Sites database was reviewed to identify if any new sites had been added since the completion of the Hudson River Responsiveness Summary (RS) Report (USEPA, 2002). It was concluded that there were no major additions made to this database at the time this search was conducted, and as a result, USEPA Regional offices, among other sources identified herein, were contacted to obtain any information on new dredging projects underway since completion of the Hudson River RS report (USEPA, 2002). The main task conducted was the development of a list of questions that identified the information needed from each dredge site. Follow-up conversations were held with past surveyed dredge site contacts to obtain recently released reports and information with regard to project performance. Records of Decision (RODs) recently issued by USEPA were reviewed to identify additional dredging sites to contact for specific site information outlined in the questionnaire. Dredging reports obtained were reviewed for pertinent information. A case study narrative was then prepared for each dredge site This information was tabulated for quick reference for other team members and to allow for comparison between various dredge sites. Malcolm Pirnie/TAMS-Earth Tech 2 Public Review Draft – May 2003 Appendix: Case Studies of Environmental Engineering Performance Standards Dredging Projects Development of List of Questions As a first step in the search for the information needed to support the performance standards, a list of questions was compiled by members of the residuals, resuspension, and productivity teams and assembled into an extensive questionnaire. This questionnaire served as a guide for the case study task force in soliciting information from various dredge sites. In addition, a copy of the questionnaire was available in electronic format for electronic mailing to any contact who agreed to provide specific information on a given project. This questionnaire also served as a guide for telephone conversations with project contacts to ensure all pertinent available information was obtained. Copies of the questionnaire were distributed to project personnel associated with various dredge sites and to different parties within the USEPA. The questions utilized in the case study survey are as follows: General Site Details • What type of dredge equipment was used, mechanical or hydraulic? • How many dredges were used in the river to meet removal goals? • How was removal of debris such as large boulders and tree limbs handled; with a separate dredge specifically used to remove debris ahead of “removal” dredge or with the selected removal dredging equipment as encountered in the excavation area? • What was the average dredge cycle time? • What size mechanical bucket was used or size of hydraulic cutterhead? • How much water was entrained in the mechanical bucket per cycle? • What was the depth of cut achieved per dredge bite/pass of dredge? • How long did it take to reposition the dredge? How often did the dredge require repositioning? • What was dredged sediment loaded into? • What was the dredging pattern? (channel to shore and downriver? How were multiple dredges positioned in the river?) • Was the area backfilled? What method of backfill placement was used? • Were wetlands dredged from the river? What type of equipment was used? What was the corresponding productivity in these areas? • Was shoreline dredging required? How was this accomplished? How were banks stabilized following dredging? • Were silt curtains used to create an enclosed dredging zone? How was equipment moved into and out of the area? Did this impact productivity? • How was the dredge and scow positioned in the river? • What downtimes occurred and how often which impacted expected productivity? • What were the main dredging limitations? What were the main limitations on productivity? Malcolm Pirnie/TAMS-Earth Tech 3 Public Review Draft – May 2003 Appendix: Case Studies of Environmental Engineering Performance Standards Dredging Projects Dredge Productivity • What contaminants and level of contamination were removed? • Was more than one type of sediment commodity handled (TSCA and Non-TSCA for instance)? • What was the sediment type? (Primarily cohesive, Non-cohesive, rocky) • Where was dredging conducted? (along shore, within channel, or both?) • What was the bathymetry of the river system? • What ranges of removal depths were required? • What was the average depth of removal required? • What volume of sediment required removal? • What was the dredging season used? • Was the expected dredging schedule met? • What volume was removed per day or week? What was the expected volume to be removed per day or week? Were removal goals met? • What were the main problems encountered? • Were community issues such as noise and odor a concern? If so, how were they handled? • Were residents located along shore near the target dredging area? Residuals • Could you provide a report discussing the dredging operation and results? • What type of dredging equipment was used? • Can you provide analytical data for all pre dredging, post dredging and post backfill sediment samples and measured parameters