Project Title:

Phosphate-Based Heavy Metal Stabilization Technologies for Contaminated Sediments and Dredge Material

Principal Investigator(s):

Dr. Taylor Eighmy, University of New Hampshire

Bradley Crannell, University of New Hampshire

Dr. Les Butler, Louisiana State University

Dr. Frank Cartledge, Louisiana State University

Advisory Board:

Mr. Dave Hartman, N.H. Office of State Planning

Dr. Tom Fredette, U.S. Army Corp of Engineers

Mr. Peter Kinner, Normandeau Associates Incorporated

Mr. Mark Lyons, Wheelabrator Environmental Systems

Mr. Peter Wellenberger, Great Bay NERR

Dr. Chuck Nieder, Hudson River NERR

Dr. Mike De Luca, Mullica River NERR

Dr. Chris Deacutis, Narragansett Bay NERR

Accomplishments ------ CLICK HERE TO VIEW APPENDICES

Tasks Scheduled for this reporting period:

1. The reactive barrier diffusion study will continue throughout the reporting period. LSU will be tracking metal diffusion using SXM to determine the best point to stop the experiments and measure the diffusion profiles in 128 diffusion columns.
2. The batch phosphate treatment optimization experiments will be run and nearly completed.
3. The optimum treatment formulations will be determined for the primary treatment study involving three sediments.

 

Progress on tasks for this reporting period:

1. Analysis of the reactive barrier diffusion study has been conducted throughout the reporting period. At the University of New Hampshire the first set of diffusion tubes have been sacrificed with lead concentrations, pH, and Eh being measured. Louisiana State University has been measuring concentration profiles of critical tubes during the reporting period. The raw data from these results are presented in Appendix A. The initial results are very promising and are beginning even at this early stage to display an inhibition of diffusion with several forms of phosphate barriers. LSU has been working to greatly improve the automation of the analysis system. They have succeeded in creating a computer/motor driven sample holder, which automates the repositioning of the samples. This is a critical step given the large number of samples we intend to analyze, and that each sample is analyzed at approximately 20 points on the X-axis. The current beam line being used at the CAMD facility in Louisiana is a relatively low energy beam, which requires long exposure times for concentration determinations at each data point. Therefore, we have prioritized the samples, and are monitoring the diffusion of a select number of samples (Appendix B). The entire sweet of diffusion tubes will be analyzed when a high-energy X-ray beam is made available from the CAMD facility. LSU has also nearly complete an automated data collection system, which converts the raw data collected at the CAMD facility into metal concentration gradients.
   
   
2. Base line analysis of the solubility of heavy metals in untreated Newtown creek sediments has been completed for the response variables pH and Eh (Appendix C). Results are as anticipated that lower pH, and increased oxidizing conditions lead to increased metal solubility. Some elements such as calcium are shown to be unaffected by redox conditions. The initial batch phosphate treatments have been completed and results are presented in Appendix D. Extensive methods for these treatments have been written and are presented in Appendix F. Treatment was effective in reducing Zn solubility, but not effective on Pb and other metals.

   To improve the treatment effectiveness a second set of preliminary treatments has been designed, which lower the solution pH to 4 instead of 2, and use calcium instead of sodium hydroxide to raise the solution pH. See appendix E for complete treatment procedures. These treatments have been completed, but results were not returned in time for this report.

3. Preliminary formulations for the primary treatment study are started, but without final confirmation from the second set of preliminary studies, it is impossible to call them finished. This is anticipated to be completed very early in the next reporting period, and should not cause any significant delays in the research.
   
   
4. Work has begun on base line analysis of the untreated sediments and the various phosphate sources, to characterize their elemental (Appendix F) and mineralogical compositions (Appendix G and H). High concentrations of metals in the Idaho phosphate sources are of some concern and may limit the usefulness of this one treatment material (Appendix F). High phosphate concentrations were observed in the Florida phosphate sample (Appendix F). Elemental analysis of four sediments revealed Newtown Creek to contain on average the highest concentrations of heavy metal contaminants. XRPD analysis of phosphate samples has shown that fluorapatite and carbonatehydroxylapatite are the primary sources of phosphate in the Florida and Idaho phosphate samples (Appendix G). XRPD analysis of the three untreated sediments shows the major mineral phases to contain quartz, aluminum silicates, and iron sulfides. Further analysis of minor phases found in these sediments is continuing (Appendix H).
   
   
5. Mr. Allen Beck of the Narragansett Bay NERR has retired and has been replaced on the board by Dr. Chris Deacutis who is filling his position and the Narragansett Bay NERR. His experience and the proximity of the Narragansett Bay NERR to the Providence River sediment collection site will make him a valuable addition to the team.

Tasks and activities for next reporting period

1. Analysis of diffusion profiles to determine rates of diffusion and diffusion retardation due to the reactive barrier.
2. Determination of products formed at the reactive barrier interface during diffusion.
3. The main treatment study is to begin during this reporting period, treating all three contaminated sediments with an ideal phosphate treatment regime.
4. The analysis of sediments treated in the main treatment study will begin.
5. Moving equipment to new higher energy beamline at CAMD facility, which is scheduled to begin construction on March 1, 2000. Begin analysis of Pb, Zn and Cd diffusion with new beamline.

Expenditures

Expenditures to date have been within the range anticipated to date. Significant analytical costs were incurred during this reporting period, as was anticipated. A donation to the project was received from JANCO Corp. in Dover, New Hampshire of two large PVC stands to hold parts of the leaching systems.