Sediments

Sediment Assessment

We perform sediment evaluations for the purposes of both human health and ecological risk assessments.  We evaluate ecological sediment quality based on sediment toxicity to invertebrate organisms at the bottom of the aquatic food chain. Occasionally, we will move up the food chain and test fish or other aquatic species as a second line of evidence. For assessing human health, we use EPA methods for calculating toxicity based on constituents present in sediments.  We have sampled, analyzed and evaluated for our clients sediment toxicity in canal bottoms, bayous, canals, rivers and inundated uplands, forests and wetlands.  We can provide for you the best current science for sediment assessment, and based on the evaluation, perform a remediation if necessary.

Sediment Remediation

MP&A has provided design, value engineering, analyses, critique and comment on many proposed and ongoing sediment remediation projects in the U.S. and New Zealand. Most of our sediment work has involved remediation of PCB, chlorinated solvent or metal impacted sediments, but we have also had major participation in reservoir capacity and channel maintenance projects dealing with non-contaminated sediments. We have developed mathematical and visual models to track particle mass and contaminant mass through the dredging, slurry transport, dewatering, disposal and water treatment processes. These models can work forwards or backwards to predict production rates or to confirm in situ solids concentrations. 

We have performed numerous bench scale process simulations, analyses, scale-up, design and cost estimates for dredging and dewatering projects. Additionally, our team has:

  • Designed daily tracking forms to monitor progress on sediment remediation projects
  • Performed project forensic analyses on failed dredging projects
  • Designed and built our own sediment sampling equipment to best collect nearly undisturbed sample cores for analyses
  • Monitored, measured and mapped placement of sand caps per design specifications
  • Designed dredge prisms based on sample analytical results
  • Prepared maps with quantity and mass predictions to meet remediation goals
  • Designed turbidity control systems and downstream monitoring programs for dredging and in-water excavation programs