Dredge work that potentially impacts federally regulated waters requires a permit from the Army Corps of Engineers. The New England District of the Corps (CENAE) is responsible for permitting work conducted in Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont.

Although the guidance document for the dredged material program, (Regional Implementation Manual for the Evaluation of Dredged Material Proposed for Disposal in New England Waters, (RIM), 2004), has not been revised or amended, there have been administrative changes. In some cases, this has resulted in confusion on the side of applicants, the need for revisions to project plans, and extending project schedules. As of this date, some of the changes observed in recent private dredge projects have included the following:

  • Reinterpreting the term “significant stratification” for core samples. According to the RIM section 4.2 Sampling of Proposed Dredged Material,

In instances where significant distinct vertical stratification (at least 2.0 feet) is evident in samples, subsampling and testing of each layer (e.g. sand vs. silt) may be required to adequately characterize the materials.

Recently CENAE has not interpreted that at least 2 feet is needed for a layer to be considered significant.

Additionally, this change in approach can be seen in the subtle language shifts observed in Sampling and Analysis Plans issued by CENAE. Older documents used the following language,

If the cores show significant stratification, in the opinion of the sampling crew, subsamples should be made of each layer.

Recent documents use the following language,

If any core shows significant stratification or obvious signs of contamination in the opinion of the sampling crew, in consultation with NAE staff, then subsamples shall be made of each layer.

The two key changes are the insertion of NAE staff in the opinion of significance and subsampling is no longer a “should” statement, but a mandatory “shall” statement.

  • No longer requiring the collection of the reference site samples for use in testing.

In the past these materials were analyzed along with the project samples. The performance of reference site samples were used in statistical comparisons with project samples for the Suspended Particulate Phase (SPP), Solid Phase and Bioaccumulation Assays. Recently CENAE has provided standard reference data sets, generated from recent historical data, for statistical analysis of data in the Solid Phase and Bioaccumulation Assays. The elutriate samples analyzed in the SPP assays are now being compared to the performance of the laboratory control samples.

  • Allowing submission of supplemental data to support a finding of no significant toxicity in the SPP testing.

In situations where the ammonia concentration in the elutriate solution could be toxic to the test organisms, CENAE has developed an additional procedure for making this evaluation. Essentially the sediment is treated to reduce ammonia concentrations and the treated sediment sample is used to create another elutriate solution. An additional SPP assay is conducted with the ammonia mitigated sediment elutriate sample.

Overall, as elements of the dredge program continue to change, it is important that projects are more closely scrutinized for meeting compliance. This also means that projects may require more coordination than previously required, and may take more time to complete. Finally, there are aspects of these changes that also impact project costs. This includes changes to sampling efforts, volumes being collected, and incorporation of a new set of testing.

Stakeholders need to pay particular attention to this line in the RIM, “The applicant should know that additional information may be required on a project-by-project basis.” It is clear that the current Sampling and Analysis Plans should be regarded as a key piece of communication and the expectations of regulators may not be the same as previous dredge studies.

For More Information
Have questions about dredge material? Need help with understanding your permit and required compliance testing? Start a conversation now.

Renée Ashley McIsaac

Project Manager

Renee brings over a decade of analytical experience to her role as project manager at our Hampton, NH laboratory which specializes in Environmental Toxicology and Chemistry.