Risk assessment of metal leaching into groundwater from phosphate and thermal treated sediments

Peter K. Ndiba, Lisa Axe

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Beneficial reuse as an alternative to disposal is increasingly being considered in management of contaminated sediments dredged from harbors. The risk of metal leaching into groundwater in reuse of phosphate and thermal treated sediments was assessed with sequential extraction, synthetic precipitation leaching procedure (SPLP), and leaching as a function of pH and liquid to solid ratio (L/S). Sequential extraction revealed that phosphate addition at 5% by dry weight, followed by calcination at 700°C reduced metal association with exchangeable/carbonate and organic phases and increased that with sparingly soluble residuals. Over the pH range 4 to 9, metal leachability varied by two to four orders of magnitude while varying L/S over 5 to 100 showed little difference. The SPLP revealed that risk to groundwater criteria based on applying a dilution attenuation factor (DAF) of 13 (New Jersey) to groundwater quality levels were achieved. Risk criteria based on a DAF of 1 (Florida and Wisconsin) were exceeded for Pb, Cd, and Mn; thermodynamic analysis demonstrates that the criteria cannot be satisfied should dissolution control pore water concentrations.

Original languageEnglish (US)
Pages (from-to)427-434
Number of pages8
JournalJournal of Environmental Engineering
Issue number4
StatePublished - Apr 2010

All Science Journal Classification (ASJC) codes

  • General Environmental Science
  • Environmental Engineering
  • Environmental Chemistry
  • Civil and Structural Engineering


  • Groundwater quality
  • Heat treatment
  • Heavy metals
  • Leaching
  • Lead
  • Pollution
  • SPLP
  • Sediment


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