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Physical and Chemical Testing of Dredged Material

Physical and Chemical Testing of Dredged Material

Note: This blog is an excerpt from the SERIM* (Southeastern Regional Implementation Manual) concerning the physical and chemical testing of dredged material.

5.0    PHYSICAL AND CHEMICAL TESTING OF DREDGED MATERIAL

Testing is frequently required to characterize the physical and chemical properties of sediments proposed for dredging and disposal. The following information supplements Section 9.0 of the 1991 Green Book and Section 2.8.1 of the QA/QC Manual (EPA, 1995). Strict adherence to established testing protocols and detection limits while conducting all analyses will aid in expediting review and concurrence for projects. Any deviation from these protocols should be approved by the USACE SAD district and EPA Region 4 prior to analysis. Such deviation should be clearly defined in the SAP (see Sections 2.2 and 4.1). Established QA/QC procedures must be followed (see Section 8.0).

5.1   Physical Analysis

Sediment proposed for dredging and disposal and reference sediments should be analyzed for grain size distribution, TOC, and total solids/percent moisture (Table 5-1). In addition, specific gravity, bulk density, and Atterberg limits may be required on a case-by-case basis. Atterberg limits should be determined when clumping of dredged material is expected during disposal (e.g., new work projects in cohesive clays). The grain size analysis should be conducted according to the methods described in Plumb (1981) or ASTM (2002) and reported as percentages retained by weight in the following size classes, at a minimum:

  • Gravel
  • Coarse Sand
  • Medium Sand
  • Fine Sand
  • Silt/Clay (expressed as “Fines”)

Gravel and sand fractions should be separated using the standard sieve sizes indicated in Table 5‑1 and reported as cumulative frequency percentages (Section 7.1). The USCS should be utilized and each sample assigned the appropriate two-letter group (see ASTM, 2006). There may be cases where silt and clay fractions will need to be distinguished. USACE SAD districts and EPA Region 4 will provide guidance on a case-by-case basis on whether it is needed. Silt and clay fractions should be quantified by hydrometer (ASTM, 2002), pipette, or Coulter Counter (Plumb, 1981). Use of a laser diffraction grain size analyzer is also acceptable (Loizeau et al., 1994). Total solids and percent moisture should be measured as described by Plumb (1981) or APHA (1995).

It should be noted that the results of the above physical analyses may be used to support compliance with one or more of the three exclusionary criteria in 40 CFR 227.13(b) for ocean disposal (see Section 3.1.1).

 

Table 5-1. Parameters Used for the Physical Characterization of Sediments

Parameter

Method

Measure/Quantitation Limit

Grain Size Distribution

Plumb, 1981; ASTM, 2002

 

Gravel (>4.75mm)

Retained on No. 4 sieve

Coarse Sand (2.0-4.75mm)

 

Passing through No. 4 sieve and retained on No. 10 sieve

Medium Sand (0.425-2.0mm)

 

Passing through No. 10 sieve and retained on No. 40 sieve

Fine Sand (0.075-0.425mm)

 

Passing through No. 40 sieve and retained on No. 200 sieve

Silt (0.005-0.075mm)

 

As determined by hydrometer, pipette or Coulter counter/laser particle size analyzer

Clay (<0.005mm)

 

As determined by hydrometer, pipette or Coulter counter/laser particle size analyzer

Total (percent) Solids

Plumb, 1981

Value based on mass. 1.0%

Total Organic Carbon

9060 (SW846)

0.1%

Specific Gravity

Plumb, 1981

 

Atterberg Limits*

ASTM 4318D

 

*Not needed in all cases. Consult your USACE district and EPA prior to analysis.

5.2   Chemical Analysis of Sediments

As discussed in Section 3.2.1.1, chemical analysis of sediments can be used to document compliance with applicable EPA WQC or state WQS. However, it cannot be used for determination of water column toxicity or the assessment of contaminant toxicity and bioac­cumulation from the material to be dredged. As discussed in Section 3.2.2, sediment chemistry can be used to screen out sediments that are not likely to meet the LPC or to assist in selecting a compositing or testing scheme under Tier III. It can also be used in Tier I as part of confirmatory analysis (see Section 3.1.2). It should be noted that chemical analysis of sediments is not required to document compliance with the ocean dumping criteria, but can be a beneficial tool in evaluating current and future projects.

The COCs that should be analyzed on a routine basis are listed in Tables 5-3 through 5-7. The routine metals, polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), and pesticides listed in these tables were chosen based on the requirements of 40 CFR 227.6, their toxicity, their persistence in the environment, their ability to bioaccumulate, and their widespread and consistence occurrence in the estuarine, marine, and freshwater sediments and organisms of the southeastern United States. These lists can be reduced or expanded based on site-specific knowledge of pollution sources or historical testing showing the presence or lack of presence of specific contaminants. Table 3-2 provides a list of resources for determining COCs. It should be explicitly stated in the SAP when listed contaminants will not be analyzed. One of the primary sources of dioxin-like compounds [chlorinated dibenzo‑p‑dioxins (CDDs), chlorinated dibenzofurans (CDFs), and certain PCBs] in surface water is bleached pulp and paper mills (EPA, 2001c). Dioxin-like compounds will be added to the analyte list when pulp and paper mills are or were present upstream in the watershed of the proposed dredging area unless it has been previously documented that these compounds are not present within the sediments in the vicinity of the project. Other major sources of dioxin-like substances to the air and land that could deposit in sediments include solid and medical waste incineration, secondary copper smelting, and cement kilns (EPA, 2001c). If any of these activities are present in the project vicinity, dioxin-like compounds should be considered. Appropriate methods and target detection limits for the dioxin-like compounds and any other supplemental COCs can be found in Appendix M of this document, the EPA QA/QC Guidance (EPA, 1995), the Inland Testing Manual, or the 1991 Green Book. If sediment chemistry is to be used in the screening method (Section 3.2.1.1) to document compliance with the WQC, analyses must be performed for all analytes listed in Appendix F.

The target detection limits (TDLs) listed in the tables are performance goals (EPA, 1995). Laboratory reporting limits (LRL) for each project should be at or below these values (Jones and Clarke, 2005). LRLs are the minimum levels at which a lab will report analytical chemistry data with confidence in the quantitative accuracy of that data. LRLs are adjusted for sample-specific parameters such as sample weight, percent solids, or dilution. As routine data acceptance criteria, the LRLs for each analyte should be below the listed TDL, with the caveat that some sediments with higher percent moisture content may have LRLs above the TDLs. It is the applicant’s (USACE SAD district for Civil Works projects) responsibility to meet the TDLs. Some laboratories have had difficulties in the past meeting the required TDLs because of inappropriate sample preparation and clean-up procedures to remove interfering substances typically found in marine sediments (e.g., elemental sulfur). If the TDLs cannot be attained, a detailed explanation should accompany the data providing the reasons for not attaining the required TDLs. Re-analysis may be necessary or the contaminant may have to be assumed to be present at the reported LRL. Appropriate sample preparation, clean-up, and analytical methods have been developed for estuarine/marine sediments by the National Oceanic and Atmospheric Administration (NOAA) (1993) and the EPA research laboratory at Narragansett, RI (EPA, 1993a). Established sample and clean-up procedures are presented in Table 5-2.

*Source:

USEPA/USACE. 2008. Southeast Regional Implementation Manual (SERIM) for Requirements and Procedures for Evaluation of the Ocean Disposal of Dredged Material in South­eastern U.S. Atlantic and Gulf Coast Waters. EPA 904-B-08-001. U.S. Environmental Protection Agency Region 4 and U.S. Army Corps of Engineers, South Atlantic Division, Atlanta, GA. http://www.epa.gov/region4/water/oceans/documents/SERIM_Final_August 2008.pdf

 

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