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Sediment Sampling: What Is a PONAR Grab Sampler?

 

The PONAR grab sampler is the main bottom sampling device used on vessels to study the composition of the bottom sediments of a lake or river.  The grab sampler provides a means to obtain a somewhat quantitative and undisturbed sample of the bottom material. It takes a bite of known surface area and penetration depth, provided that the bottom material is neither too hard or nor too soft. It is called a grab sampler because of the manner in which it obtains samples.

Early studies on Lake Michigan used oceanographic and freshwater grab samplers that were not satisfactory. Research scientists from the Great Lakes Research Division of the University of Michigan devised a new sampler, the PONAR grab sampler, that was first available for sale in 1966. The sampler is named after Great Lakes scientists, Charles E. Powers, Robert A. Ogle, Jr., Vincent E. Noble, John C. Ayers, and Andrew Robertson.

The PONAR grab sampler consists of two opposing semi-circular jaws that are normally held open by a trigger mechanism. The sampler is lowered to the bottom where contact with the bottom sets off the trigger and a strong spring snaps the jaws shut trapping a sample of the bottom inside. Fine copper screen covers the top of the jaws so that the trapped material will not wash out as the sampler is retrieved.

For the full article, including a description of how the bottom material is studied, go to http://www.gvsu.edu/wri/education/instructors-manual-bottom-sampling-31.htm.  

Source:  Excerpted from the Instructor’s Manual on Bottom Sampling and used with permission from Annis Water Resources Institute (AWRI).  www.gvsu.edu/wri/education

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Expansion of the Jacksonville Ocean Dredged Material Disposal Site Is Finalized

USACE Jacksonville and EPA Region 4 identified the need to either designate another Jacksonville ODMDS or expand the current 1‑square nautical mile (nmi2) site. ANAMAR was contracted in 2009 to prepare an Environmental Impact Statement for this multi-year, multi-faceted site designation project. Congratulations to all the people who worked on this project! The final rule will go into effect on November 13 designating the new 4.56‑nmi2 area.

jax port

Jax Sampling pic 1 FILEminimizer

Jax Harbor sampling pic 3 FILEminimizer

 

Jax Sampling pic 1 FILEminimizer
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2014 Mouth of the Columbia River Deep Water Site and Shallow Water Site Monitoring Series, Part 2 of 4: Grab Sampling

Part 2 of our Oregon adventure series describes the grab sampling effort that was part of the June and October surveys.  During the two surveys the team collected benthic samples at 40 locations in and around the drop zones of the DWS .  During the October survey, the team collected sediment samples from 45 locations for physical and chemical analysis.  We used a Gray O’Hara modified box corer to collect samples at water depths ranging from 178 to 279 feet.

The objectives of the study were to:

  • Provide a physical characterization of the benthic habitat
  • Assess levels of chemicals of concern
  • Characterize the benthic invertebrate community

 

Michelle pic 1

Deploying the grab sampler. The ropes helped keep the sampler from swinging and ensured that it reached the water surface safely. The sampler weighed 600 lbs.

 

 

Michelle pic 2

Emptying a sample into a decontaminated stainless steel pan.

 

 

michelle pic 3

An intact sample in the box core.

 

 

michelle pic 4

Washing the benthic sample through a 0.5-mm-mesh sieve box.

 

 

michelle pic 5

The remaining material (organisms plus coarse sediment) was decanted into a jar and fixed with 10% buffered formalin solution.  Sample organisms were later taxonomically determined at the lab.

 

 

michelle pic 6

Homogenizing a sediment sample prior to containerizing in glass sample jars.

 

 

michelle pic 7

An unlucky Dungeness crab caught in the box corer. 

 

 

michelle pic 8

The box corer stand also makes a nice throne.

 

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ANAMAR’s Work in Charleston Harbor Profiled in "Dredging Today"

ANAMAR’s Work in Charleston Harbor Profiled in "Dredging Today"

(Pictured above is the cooper marl we frequently encountered while collecting core samples)

The Charleston Harbor Federal Navigation Channel covers an area of approximately 14 square miles and is formed by the confluence of the Ashley, Cooper, and Wando rivers. Maritime interests want the harbor channel deepened beyond 45 feet so the Port of Charleston can handle the larger container ships that will routinely call when the expanded Panama Canal opens in 2015. In response to this need to accommodate larger ships and increasing ship traffic, a feasibility study is being conducted for the Charleston Harbor Navigation Improvement Project to analyze and evaluate improvements to Charleston Harbor. The Post-45 feasibility study examines the economic benefits and environmental impacts of the deepening project and determines what depth would be recommended for construction. ANAMAR was contracted to conduct sediment evaluations to determine if the proposed dredge material is suitable for disposal in the Charleston Harbor ocean dredged material disposal site (ODMDS) and to help identify potential beneficial uses for dredged material such as habitat development, shore protection, or beach nourishment.

Charleston 103012 007 FILEminimizer

ANAMAR managed all sampling operations and worked closely with subcontractors to coordinate logistics. The sampling plan included collection of vibracore samples at 105 sites, plus grab samples at the reference station, and site water samples at three locations for elutriate preparation. Due to the size of the project, the sampling effort took nearly 4 weeks to complete and presented some unique challenges. Inclement weather caused by Tropical Storm Sandy followed 2 days later by a winter storm resulted in minor delays in sampling operations. This area also experiences six-foot tidal fluctuations resulting in very strong currents during incoming and outgoing tides; therefore, the sampling team had to plan daily sampling operations during workable currents (i.e., slack tides). Since sampling was taking place within the shipping channel and berthing areas, the captain maintained regular communication with the ships so that sampling would not interfere with shipping traffic. The physical composition of the sediment itself also proved to be challenging. Most of the sediment in the areas of interest was highly consolidated Cooper Marl, which was difficult to penetrate and to remove from the core barrel. A method was developed in the field to pressurize the core barrel using compressed air to extrude sample material from the barrel. This “on-the-fly” innovation helped the field effort stay on schedule.

PB050043 FILEminimizer

Coordinating sample delivery with the chemistry and bioassay laboratories to meet holding times while field operations were ongoing required multiple sample shipments due to holding times and the amount of time required to collect all the samples. It was necessary to run the bioaccumulation tests in two batches due to holding times and the laboratory space required for such a large number of samples. Close coordination with the laboratories and couriers was critical.

PB050052 FILEminimizer

ANAMAR succeeded in collecting all the required sample material and processed and shipped the material to the laboratories within holding times. ANAMAR reviewed and evaluated all the laboratory data and produced a report summarizing the results of the physical, chemical, and toxicological analysis of sediment, elutriate, water, and tissue samples of the proposed dredge material collected from the project area.

Below is a quotation from the news article: Dredging Today (July 2, 2015) "Post 45 Project Gets Funding"

"The Charleston Harbor Post 45 Deepening Project is the first project in the U.S. Army Corps of Engineers to go through the Corps’ new Civil Works Planning Process from start to finish.

This has enabled the Charleston District to reduce the initial study timeline of five to eight years down to less than four years, and reduce the initial study budget from $20 million to less than $12 million dollars. This project will serve as a model for Corps civil works projects around the world."

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ANAMAR's Recent Work Profiled in International Dredging Review

ANAMAR's Recent Work Profiled in International Dredging Review

ANAMAR’s recent work with the U.S. Army Corps of Engineers–Jacksonville District to sample Jacksonville Harbor has been profiled in International Dredging Review.  The project is part of the Jacksonville Harbor Deepening, one of the five major ports mentioned in President Obama’s “We Can’t Wait” initiative from 2012.  Check out the International Dredging Review news article to learn more!

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REQUIREMENTS FOR MPRSA OCEAN DISPOSAL EVALUATIONS

REQUIREMENTS FOR MPRSA OCEAN DISPOSAL EVALUATIONS

The following information was taken directly from Appendix C of the SERIM (EPA and USACE 2008; see the reference at the end of the article) and is required for completion of an MPRSA Section 103 evaluation.

Information should not be repeated, but referenced where material is needed for more than one part of the evaluation documentation.

1. Dredging and Disposal Project Information

a.  A map showing dredging locations/boundaries and delineating dredging units. Shall include range stations to adequately delineate project limits

b.  Core boring logs (if available) and other historical and current sampling stations keyed to the map

c.  Volume of material to be dredged by dredging unit

d.  Percentage of fine-, medium-, and coarse-grained material by dredging unit

e.  Bathymetric information for the channel to be dredged with the project dredging depth contour highlighted

f.   Design depth (including overdredge depth or advance maintenance) and width for each dredging unit or project reach

g.  Expected method(s) of dredging, transport, and disposal of material

h.  Expected start, duration and end of dredging, transport, and disposal of material

i.   Proposed disposal location (or zone) within the ODMDS

j.   Historical compliance with ODMDS site designation and SMMP conditions

2. Exclusionary Criteria - 40CFR §227.13(b) [Tier I]

a.  Rationale for meeting the exclusionary criteria (choose one):

i.   The dredged material is composed predominately of sand, gravel, rock, or any other naturally occurring bottom material with particle sizes larger than silt, and the material is found in areas of high current or wave energy

(1)  Grain sizes of the dredged material (from 1d above)

(2)  Current data from current meters or tide gauges (if available)

ii.   The material is substantially the same as the substrate at the disposal site and the dredging site is far removed from sources of pollution so as to provide a reasonable assurance that such material has not been contaminated by such pollution.

(1)  Grain sizes of the dredged material (from 1d above)

(2)  Grain sizes of the material at the disposal site

(3)  Locations to (keyed map), quantities, and types of pollutants discharged upstream of the dredging area (see Section 3.1.1 of the RIM for data sources)

(4)  Results of previous testing in the area demonstrating lack of contamination

b.  If one of the exclusionary criteria is met, items 3 through 6 below need not be addressed.

3. Need for Testing (Tier I)

a.  Site history narrative including potential sources of contamination

b.  Locations (keyed to map), quantities, and types of pollutants discharged upstream of the dredging area (see Section 3.1.1 of the RIM for data sources)

c.  History of dredging in area

d.  Summary of the past physical, chemical, and biological tests including a narrative description of past suitability determinations

e.  Maps showing all past sampling stations (from 1b above)

f.   Description of any events that have occurred since the last sampling or dredging event that might influence sediment chemistry or bioassay results

4. Water Column Determinations - 40CFR §227.6(c)(1) and 227.27(a) and Suspended Particulate Phase Determination - 40 CFR §227.6(c)(2) and 227.27(b) [Tiers II-III]

a.  Evaluation of the Liquid Phase - Water Quality Criteria Choose one of the following:

i.   Sediment Chemistry Screen

(1) Table showing for and analyte: sediment chemistry value, each station estimated elutriate concentration, background concentration, applicable marine water quality criteria or standard, and the required dilution to achieve the criteria/standard

(2) ADDAMS STFATE result (if required) for the contaminate requiring the most dilution

(3) Sediment testing report (or)

ii.   Elutriate Analysis

(1) Table showing for each station and analyte: elutriate concentration, background concentration, applicable marine water quality criteria or standard, and the required dilution to achieve the criteria/standard

(2) ADDAMS STFATE result (if required) for the contaminate requiring the most dilution. Include any special disposal practices (e.g., minimum distances from site boundaries, tidal state, current magnitude/direction) that must be instituted to assure compliance.

(3) Elutriate chemistry testing report

b.  Liquid and Suspended Phase Bioassays

i.   Comparison of 100% dredged material elutriate control and dilution water (if not significantly more toxic, items ii and iii below are not required)

ii.   LC50/EC50 for each station where 100% elutriate is toxic

iii.  ADDAMS STFATE results for station with lowest LC50/EC50. Include any special disposal practices (e.g., minimum distances from site boundaries, tidal state, current magnitude/direction) that must be instituted to assure compliance

iv.  Elutriate bioassay testing report

5. Benthic Screen (optional) [Tier II]

a.  Tier II tests for benthic impact evaluation should be used only to screen out sediments that are not likely to meet the criteria or to assist in selecting a compositing or testing scheme under Tier III.

i.   Theoretical Bioaccumulation Potential (TBP) calculation

ii.   Sediment testing report

6. Benthic Determinations - 40 CFR§227.6(c)(3) and 227.27(b) [Tier III]

a   Benthic Toxicity Evaluation

b.  Benthic Bioavailability Evaluation

i.   28-day bioaccumulation exposure

ii.   Tissue chemical analysis

iii.  Comparison with FDA Action Levels and tissues exposed to the reference and risk-based analysis as required

iv.  Sediment testing report

7. Non-Testing Related Regulatory Issues: Subparts B,C,D and E of 40CFR§227

a.  Subpart B - Environmental Impact

i.   §227.4 Criteria for Evaluating Environmental Impact

ii.   §227.5 Prohibited Materials

iii.  §227.7 Limits established for specific wastes or waste constituents

- address presence of pathogens, biological pests, non-indigenous species

iv.  §227.8 Limitations on the Disposal Rates of Toxic Wastes; §227.11 Containerized Wastes; and §227.12 Insoluble Wastes

v.  §227.9 Limitations on Quantities of Waste Materials

- include project volumes

- provide site capacity if determined

vi.  §227.10 Hazards to Fishing, Navigation, Shorelines, or Beaches -reference appropriate section(s) of the site designation EIS/EA if necessary

b.  Subpart C - Need for Ocean Dumping

i.   For federal projects, provide authorization and reference Feasibility Study or other NEPA document providing assessment of disposal alternatives.

ii.   For non-federal projects, the alternative disposal alternatives should be summarized and assessed. The final determination is made in the USACE Statement of Findings on whether or not to grant the permit.

c.  Subpart D - Impact of the Proposed Dumping on Aesthetic, Recreational, and Economic Values

i.   Reference appropriate section(s) of the site designation EIS/EA to address potential impacts of disposal at the site on recreational fisheries, commercial fisheries, shore recreation, and cultural resources with regard to disposal of dredged material at the site.

ii. Address visible characteristics.

iii. Address presence of toxics and bioaccumulative chemicals (reference 6 above).

iv. Address pathogens (reference 7.a.iii above).

d.  Subpart E - Impact of the Proposed Dumping on other Uses of the Ocean -reference appropriate section(s) of the site designation EIS/EA

8. MPRSA Section 103 Conditions

a.  Requirements (management options) to meet the Ocean Disposal Criteria

i.   Disposal zones or minimum distances from the disposal site boundaries

ii.   Ambient disposal conditions (e.g., current or tidal conditions)

iii.  Limits on disposal vessel size or discharge rates

b.  Requirements necessary to meet site designation conditions

i.   Grain size limitations

ii.   See 40CFR Section 228.15(h)

c.  Requirements necessary to meet the requirements of the disposal site SMMP.

i.   Disposal zones

ii.   Limits on oceanographic conditions for disposal

iii.  Disposal monitoring requirements

iv.  Reporting requirements

d.  All conditions must be implemented through permit conditions or contract specifications for federal projects. The draft permit conditions/contract specification must be included as part of the MPRSA Ocean Disposal Evaluation Documentation. These are typically available from the SMMP.

 

Citation:

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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Sampling Control Site Stations

SERIM Excerpt

Note: This blog is an excerpt from EPA/USACE’s Southeast Regional Implementation Manual (SERIM) concerning sampling control site stations.

4.4   Sampling Control Site Stations

Control sediment should be used in all bioassay and bioaccumulation tests.  Control sediment is distinguished from the reference sediment because it is selected to provide optimum conditions for the organisms.  Control samples are used to determine the general health of the test organisms during the bioassay and bioaccumulation tests, and to evaluate test protocols as part of the laboratory QA/QC program.  The coordinates of the control site or source of the control sediment should be documented in the SAP and approved by the appropriate USACE SAD district and EPA Region 4 prior to collection.

  • Control sediment shall be defined as:  "A natural sediment essentially free of contaminants and compatible with the biological needs of the test organisms such that the sediment has no discernible influences on responses being measured in the tests" (1991 Green Book, Section 1).
  • Control sediment is used in the whole-sediment bioassay tests to assess the overall health of the test species.  The average control test species mortality should not exceed 10% [30% for the zooplankton in the elutriate toxicity tests (see Appendix L)].  In the event these levels are exceeded, testing may need to be repeated.
  • The control sediment tests are not usually compared to the proposed dredged material as part of the analysis to determine whether sediments are suitable for ocean disposal.

Citation:

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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Administrative Permit Requirements

Administrative Permit Requirements

 

(Note: This blog is an excerpt from EPA/USACE’s Southeast Regional Implementation Manual (SERIM) concerning sampling control site stations.)

MPRSA Section 103 permits for the transportation of dredged material for the purpose of disposal at an approved ODMDS are issued by USACE SAD district offices.  MPRSA Section 103 applications should be consistent with USACE permitting regulations in 33 CFR Parts 320 to 330.  All information submitted as part of the MPRSA application process should also comply with EPA Ocean Dumping Regulations in 40 CFR Parts 220 to 228.

USACE SAD districts will coordinate all sediment testing plans with EPA Region 4.  Pre-application conferences to prepare appropriate sampling plans are encouraged for all MPRSA Section 103 permit applicants.  Upon receiving all necessary information from the applicant, USACE SAD districts will provide for EPA Region 4 review the complete documentation of the project evaluation conducted under the SAP in the form of a Section 103 evaluation.  This information can be provided prior to, with, or after the Public Notice.  The evaluation reports will be consistent with the information provided in Appendix C and will be accompanied by a Section 103 Sediment Testing Report (Appendix D) and draft permit conditions necessary for implementation of the ODMDS Site Management and Monitoring Plan (SMMP). 

USACE SAD districts are responsible for coordination of all federal actions, including EPA Region 4 concurrences, pertaining to MPRSA Section 103 applications.  The applicant may also need to coordinate activities with the appropriate state regulatory agencies for compliance with Section 401 of the Clean Water Act and the State Coastal Management Program [Coastal Zone Management Act Section 307(c)].  A schedule for coordination is provided in Appendix B.

The permit process is outlined in Figure 2-1 and consists of 10 main steps:

  1. Pre-application Consultation:  Includes discussion of the need for the dredging project and a discussion of alternatives and the qualitative and quantitative information required by the District Engineer for use in evaluating the proposed dredged material.
  2. Evaluation of Dredged Material Proposed for Ocean Disposal:  Includes development, approval, and implementation of the SAP.  This step should include close coordination between EPA Region 4, USACE SAD districts, and the applicant (see Section 2.2).
  3. Permit Application: According to 33 CFR 325.1, a permit application must include the items listed in Table 2-1.
  4. Review of Application for Completeness:
    1. Additional information is requested if the application is incomplete.
      1. Applicant is given the opportunity to respond according to each district’s review schedule.  
  5. Public Notice:  If the application is complete, USACE issues a Public Notice per 33 CFR 325.3.  The notice must include all of the information required in 33 CFR 325.3(a), including the information required by 40 CFR 225.2(a) (see Table 2-2).  A supplemental revised or corrected Public Notice will be issued if the District Engineer believes the new information affects the review of the proposal. 
  6. USACE Section 103 Evaluation:  Either before, with, or after issuance of the Public Notice, USACE’s District Engineer will submit to EPA Region 4 its determination of compliance with criteria (40 CFR 227 and 228) and the basis for that determination in the form of a Section 103 evaluation (see Appendix B).  If the District Engineer or EPA Region 4 does not find the material to be in compliance, the project is modified or the waiver process is initiated (40 CFR 225.3 and 225.4):
    1. Economically feasible alternatives are reviewed.  If an adequate alternative is identified, the decision to deny a permit is discussed in either a Statement of Findings or Record of Decision.
    2. If no alternatives are available, a request for waiver from the Chief of Engineers is applied for.
    3. The EPA Administrator reviews the waiver request and either denies or grants the waiver.
  7. EPA MPRSA Review:  Independent review of the information will be performed to determine whether the disposal activity complies with the criteria found in 40 CFR 227 and 228.  This includes a review of all necessary physical, chemical, and biological tests.  Refer to Table 2-3 for detailed explanations of EPA MPRSA review periods.
  8. USACE Public Interest Review:  USACE must consider all comments, suggestions, and concerns provided by all commenters and incorporate their comments into the administrative record of the application. If the permit is determined to be contrary to the public interest, the decision to deny a permit is discussed in either a Statement of Findings or a Record of Decision.
  9. Other Permits:  If the permit is not contrary to the public interest, review of other required permits needs to be addressed.  If applicable, other application permits from federal and state agencies need to be obtained.
  10. Permit Issued:  A decision to issue a permit is discussed in either a Statement of Findings or a Record of Decision, and a Permit Public Notice with a list of permit decisions is published by USACE.


Table 2-1.  Permit Application Items [33 CFR 325.1]

a.

A complete description of the proposed activity, including necessary drawings, sketches, or plans.

b.

The location, purpose, and need for the proposed activity; scheduling of the activity; names and addresses of adjoining property owners; location and dimension of adjacent structures.

c.

A list of authorizations required by other federal, interstate, state, or local agencies for the work, including all approvals received or denials already made.

d.

The source of the material; the purpose of the disposal and a description of the type, composition, and quantity of the material (this ideally includes information necessary to determine if the material is in compliance with the criteria); the method of transportation and disposal of the material; and the location of the disposal site.

e.

The application should include:  (1) an evaluation of dredged material disposal alternatives, including an examination of potential beneficial uses of the proposed dredged material and a consideration of alternative disposal options before selecting the ocean disposal option (40 CFR Sections 227.14 to 227.16), and (2) documentation of the criteria used as the basis upon which selections or rejections were made.  If prior evaluations are current, reference to them is encouraged.

f.

Include written documentation of the site dredging history, including all results from previous sediment testing (both abiotic and biotic) and a general survey of other prior or current dredging activities at or near the site.  If prior evaluations are current, reference to them is encouraged.

g.

If the ocean disposal application for re-certification of the proposed maintenance dredged material is currently covered or was previously covered under a MPRSA Section 103 disposal permit, the permit number (or Public Notice and date) should be provided.  If more than 3 years have passed since the last evaluation was conducted for the dredge site, or if data are considered to be inadequate, the USACE SAD district, in consultation with EPA Region 4, will assess the need for additional evaluation.

h.

Give detailed information along with written documentation on known or suspected site contamination including oil, chemical, or waste spills and any other discharges that may cause contamination of the proposed dredging site.  The local U.S. Coast Guard and Port Authority offices shall be consulted to obtain additional information on spills or suspected contamination.  Results of the consultation shall be documented as part of the application.  Any chemicals known to contaminate or suspected of contaminating the proposed dredging site must be added to the list of possible COCs (see Section 5.0 of this manual).

 


Table 2-2.  Public Notice Information* Specific to MPRSA Section 103 Public Notices [33 CFR 325.3(a)(17) and 40 CFR 225.2(a)]

 

Regulatory Requirement

Examples/Guidance

1.

The location of the proposed disposal site and its physical boundaries

Include the disposal site corner coordinates and center coordinates (latitude and longitude).  Include distance from shore and water depth.  Include disposal zone if applicable.

2.

A statement about whether the disposal site has been designated pursuant to MPRSA Section 102(c)

Include date of designation and/or CFR citation.

3.

If the proposed disposal site has not been designated by the Administrator, a statement of the basis for the proposed determination of why no previously designated site is feasible and a description of the characteristics of the proposed disposal site necessary for its designation pursuant to 40 CFR Part 228

Include a statement as to why an EPA-designated ODMDS is not feasible.  Address the 5 general (40CFR228.5) and 11 specific criteria (40CFR228.6) for the proposed site.  Detailed information is typically provided in a supplemental document such as an Environmental Assessment.

4.

The known historical uses of the proposed disposal site

Provide year site was first used.  Provide volume of material disposed at site (see Ocean Disposal Database: http://el.erdc.usace.army.mil/odd/).  Include details regarding most recent disposal project (volume, dates, physical characteristics, disposal zone if applicable).

5.

Existence and documented effects of other authorized disposals that have been made in the disposal area (e.g., heavy metal background reading and organic carbon content)

Provide summary of monitoring (bathymetry, physical, chemical, biological) that has been conducted at the ODMDS and the conclusions of the monitoring.  [For example:  there has/has not been mounding at the site; there has been a change in the grain size to a siltier/sandier bottom; there has/has not been a significant change in the taxa/diversity/biomass of macro invertebrates at the site.]

6.

An estimate of the length of time during which disposal would continue at the proposed site

Provide the anticipated date for initiation of disposal activities and the expected duration of disposal activities.

7.

Information on the characteristics and composition of the dredged material

At a minimum, provide results of physical tests.  Also provide results of chemical and biological tests on the dredged material if available.  If EPA Region 4 has concurred on the suitability of the material for ocean disposal, this should be mentioned here.  If additional tests will be conducted, this should be explained as well as how the results will be made available to the public.

8.

A statement concerning a preliminary determination of the need for and/or availability of an Environmental Impact Statement

 

* Information provided for the Public Notice and other pertinent information will be used by USACE as an aid in determining the suitability of the proposed dredged material for ocean disposal under the criteria defined in 40 CFR  Part 227 (see Appendix C for Section 103 Evaluation Report).  If the data submitted by the applicant are insufficient to evaluate the proposed dredged material and prepare the Section 103 Evaluation Report (Appendix C), USACE SAD district, with the cooperation of EPA Region 4, will request additional information. 

Citation:

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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Port Aransas Sampling Expected to Begin Tomorrow

Port Aransas Sampling Expected to Begin Tomorrow

 

ANAMAR’s sampling team, Terry Cake and Manager Michelle Rau, is in Corpus Christi Bay area and will start sampling operations tomorrow. The sampling will be performed at the federally maintained Corpus Christi Ship Channel and the offshore ocean dredged material disposal site (ODMDS). Good luck to the sampling crew!

 

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ANAMAR Awarded Contract with the U.S. Army Corps of Engineers, Galveston District

ANAMAR Awarded Contract with the U.S. Army Corps of Engineers, Galveston District

 

The U.S. Army Corps of Engineers, Galveston District has awarded ANAMAR a contract to perform environmental services for the collection and analysis of water and sediment samples.  The sampling will be performed at the federally maintained Corpus Christi Ship Channel and the offshore ocean dredged material disposal site (ODMDS).

The purpose of the testing is to evaluate shoal material prior to maintenance of the channel to determine whether unacceptable impacts would result from dredging operations.  The Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) prohibits placement of material into the ocean that would unreasonably degrade or endanger human health or the marine environment.

USACE-Galveston District employs an environmental management framework to provide structure and accountability within its business processes to help enhance and expand the positive impacts of its mission while reducing, mitigating, or eliminating potential negative impacts.

Work is expected to begin in May 2014.

 

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Now-Extinct Marine Mammals Found beneath Sediment of Chile’s Pan-American Coastal Highway during Road Construction

Now-Extinct Marine Mammals Found beneath Sediment of Chile’s Pan-American Coastal Highway during Road Construction

Ten species of marine vertebrate were found buried in four separate levels of sedimentation, suggesting their carcasses had washed ashore in what were then tidal flats during four time periods nearly 6 to 9 million years ago. Scientists suggest that the deaths were likely caused by harmful algae blooms. Among the species found were now-extinct walrus-like whales, aquatic sloths, baleen whales, sperm whales and seals.

For more information on these findings, check out the Smithsonian press release:

http://www.eurekalert.org/pub_releases/2014-02/s-sss022514.php

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Sampling Reference Stations

Sampling Reference Stations

Excerpted from the Southeastern Regional Implementation Manual (SERIM)

4.3 Sampling Reference Stations

For dredged material evaluations for ocean disposal, the test results from proposed dredging site samples are compared to test results from appropriate reference site sediments. Reference sediment is defined as “A sediment, substantially free of contaminants, that is as similar to the grain size of the dredged material and the sediment at the disposal site as practical, and reflects conditions that would exist in the vicinity of the disposal site had no dredged-material disposal ever occurred, but had all other influences on sediment condition taken place” (1991 Green Book, Section 3.1.2). Reference sediment sampling stations are selected to simulate conditions at the proposed disposal site in the absence of past dredged material disposal. Reference sediments must be collected for each evaluation. Results from previous evaluations are not acceptable. Test organisms should be selected to minimize sensitivity to possible sediment grain size differences among the reference site, the control site, and the proposed dredging site.

Using historical reference sites and EPA Region 4 studies of reference areas, EPA Region 4 has identified preferred reference sites for each ODMDS for various grain size distributions. These sites are identified in Appendix K. One or more of these sites may be used and should be selected based on the grain size of the proposed dredged material. These reference areas shall be utilized. Alternative reference sites will be approved on a case-by-case basis.

Reference sediments may be collected from (1) a single reference-sediment sampling location; or (2) from a number of approved locations. Reference samples may be composited and tested according to guidance provided in Chapter 8 of the 1991 Green Book.

Replicate sediment samples should be collected at the reference site(s) using an appropriate collection device [see Table 5 for the EPA QA/QC Guidance (EPA, 1995)]. In most cases, a grab sample is adequate for reference sediment stations. Replicates may be composited into a single sample [see Chapter 8 of the 1991 Green Book or Chapter 4 of EPA (2001b) for guidance]. The collected sediment should be of sufficient quantity to conduct all required testing. A minimum of three replicate sediment samples from the reference site(s) should be collected for all testing [i.e., three grabs at one site or one grab at three sites or any other combination for a minimum of three grabs].

Citation: 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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What can fossils tell us about the rock surrounding them?

What can fossils tell us about the rock surrounding them?

Fossil scallops in the Coquille River as a case study

During a benthic survey off the Coquille River, Oregon, in September 2013, ANAMAR was collecting samples of epifauna using a 12-foot otter trawl when suddenly the gear encountered unidentified rock. The trawl net snagged and the cable instantly snapped, losing the gear on the seafloor in about 45 feet of water. Although many attempts were made to recover the trawl using a grapple hook off the deck of the survey vessel (R/V Pacific Storm), the gear was too entangled on the seafloor to be brought up with that method. Directly following completion of the benthic survey, an ANAMAR subcontractor returned to the site and recovered the trawl gear using SCUBA divers. The trawl was still in good shape and the remaining trawl tows were completed for the survey. In addition to finding the trawl gear, the divers also observed several fossil scallop shells embedded in the rock on the seafloor. The fossil scallops were in excellent condition (see images below). The divers were able to pry a few of the fossil shells loose for closer inspection and photography.

 

jasons coquille FILEminimizer

 

 

Because the area where the survey took place is an ocean dredged material disposal site (ODMDS), information on the naturally occurring rocks found there is of interest to agencies tasked with managing the site (U.S. Army Corps of Engineers and U.S. Environmental Protection Agency). For this reason, and also out of personal interest, I began collaborating with paleontologists to determine the identity of the fossil scallops in the hopes of learning more about the rock they were found in. I soon found my answer after contacting specialists at the Burke Museum of Natural History in Seattle, Washington. Dr. Elizabeth Nesbitt, Curator of Paleontology, graciously identified the fossil scallops as either Patinopecten coosensis or P. oregonensis based on photos I sent her. The flared portions of the shell adjacent to the hinge (called auricles) serve as key characteristics differentiating these two species. These fossils lacked auricles so they could not be identified beyond these two species. However, based on the fossils and the associated matrix, Dr. Nesbitt was able to identify the rock formation the fossils were found in!

The rocks and fossils are part of the Empire Formation which is better known from exposures about 20 miles south of the Coquille River at Cape Blanco, Oregon. The Empire Formation, composed mostly of sandstone, along with the fossils it contains, are as old as 12 million years (Miocene), but it is theorized to be closer to 8 to 5 million years (Miocene-Pliocene epoch boundary). Since we know the identity of the rock as being part of the Empire Formation, we therefore know something about its composition. In this case, the rocks that snagged the trawl gear must have been composed of sandstone and some siltstone. This formation represents sands deposited in what was then a small marine basin which now is represented only by Coos Bay. It is probable that other rocks within the ODMDS are also fossiliferous sandstone/siltstone from the Empire Formation.

The above is an example of how fossils can help us infer the identity of the surrounding substrate. In this case, the identity of the fossil scallops, along with the matrix attached to the fossils, were used to pinpoint the exact formation they represent. Knowing the formation, we then were able to learn more about the composition and approximate geological age of surrounding rocks that represent the same formation. All this information came from observing and collecting a handful of fossils incidental to recovering of some equipment from the seafloor!

Interestingly, the French word for scallop is Coquille. Thus the Coquille River, where the fossils were collected, was actually named after a scallop!

Sources:

Ehlen, J. 1967. Geology of state parks near Cape Arago, Coos County, Oregon. The Ore Bin 29(4):61–82.

Nesbitt, E. Department of Paleontology, Burke Museum of Natural History, University of Washington, Seattle, WA. Pers. comm. 12/06/13.

Portell, R.W. Department of Invertebrate Paleontology, Florida Museum of Natural History, University of Florida, Gainesville, FL. Pers. comm. 11/18/13.

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Dredging and the Disposal of Dredged Material

Dredging and the Disposal of Dredged Material

The video above is an ANAMAR production presented by Paul Berman, ANAMAR’s Quality Assurance/Quality Control Officer, explaining some of the purposes and processes related to dredging. The information below is an excerpt from the Southeastern Regional Implementation Manual (SERIM) explaining further details of the steps that are taken to minimize the impact of dredged material disposal.

Sampling Reference Stations

Excerpted from the Southeastern Regional Implementation Manual (SERIM)

4.3 Sampling Reference Stations

For dredged material evaluations for ocean disposal, the test results from proposed dredging site samples are compared to test results from appropriate reference site sediments. Reference sediment is defined as “A sediment, substantially free of contaminants, that is as similar to the grain size of the dredged material and the sediment at the disposal site as practical, and reflects conditions that would exist in the vicinity of the disposal site had no dredged-material disposal ever occurred, but had all other influences on sediment condition taken place” (1991 Green Book, Section 3.1.2). Reference sediment sampling stations are selected to simulate conditions at the proposed disposal site in the absence of past dredged material disposal. Reference sediments must be collected for each evaluation. Results from previous evaluations are not acceptable. Test organisms should be selected to minimize sensitivity to possible sediment grain size differences among the reference site, the control site, and the proposed dredging site.

Using historical reference sites and EPA Region 4 studies of reference areas, EPA Region 4 has identified preferred reference sites for each ODMDS for various grain size distributions. These sites are identified in Appendix K. One or more of these sites may be used and should be selected based on the grain size of the proposed dredged material. These reference areas shall be utilized. Alternative reference sites will be approved on a case-by-case basis.

Reference sediments may be collected from (1) a single reference-sediment sampling location; or (2) from a number of approved locations. Reference samples may be composited and tested according to guidance provided in Chapter 8 of the 1991 Green Book.

Replicate sediment samples should be collected at the reference site(s) using an appropriate collection device [see Table 5 for the EPA QA/QC Guidance (EPA, 1995)]. In most cases, a grab sample is adequate for reference sediment stations. Replicates may be composited into a single sample [see Chapter 8 of the 1991 Green Book or Chapter 4 of EPA (2001b) for guidance]. The collected sediment should be of sufficient quantity to conduct all required testing. A minimum of three replicate sediment samples from the reference site(s) should be collected for all testing [i.e., three grabs at one site or one grab at three sites or any other combination for a minimum of three grabs].

Citation: 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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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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Word from the Field: Oregon ODMDS Sampling

Word from the Field: Oregon ODMDS Sampling

 

Congratulations to the ANAMAR crew working on the Ocean Dredged Material Disposal Sites off the Oregon coast. They completed sampling eight stations in and around the Chetco ODMDS yesterday and are collecting samples from the Coquille site today. While sampling, the crew spotted a grey whale and witnessed some picturesque fog rolling through.

Pictured above is the box corer the crew used to collect samples from the Chetco ODMDS, and below is a photo of the Oregon fog.

michportlpic2 FILEminimizer

 

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Word From the Field: San Francisco DODS Survey

ANAMAR’s biologist Jason Seitz recently assisted EPA and USACE in a benthic survey of the San Francisco Deep Ocean Disposal Site (SF-DODS) aboard the R/V Point Sur 50 miles off the coast of San Francisco. During the survey, Jason and other crew spotted many of nature’s majestic creatures. In the following paragraph Jason lists some of the species observed during the survey.

“We encountered several species of marine mammals during the SF-DODS survey, including humpback whales, northern right whale dolphins, Pacific white-sided dolphins, Rizzo’s dolphins, sea otters, seals, and sea lions.  We also encountered pelagic birds such as black-footed albatross, storm petrels, shearwaters, murres, murrelets, and tufted puffins.”

-Jason Seitz


    b2ap3_thumbnail_Black-footed-albatross.JPG           

SF-DODS, an ocean disposal site for dredged materials, is regulated under the Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) and co-managed by USACE San Francisco District and EPA Region 9. SF-DODS is also the nation’s deepest disposal site. It is located along the continental slope in water depths of about 3000 meters and is just outside the Gulf of the Farallones National Marine Sanctuary.

 

b2ap3_thumbnail_ODMS-Sampling-aboard-the-Point-Sur.JPG

 

Photo's courtesy of Jason Seitz

 

 

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Significant Figures, Decimal Places, and Rounding Part II

Part II Rounding Rules

When the data collected have more sig figs than needed, the results should be rounded. Rounding removes superfluous digits from a number and can make it easier to use in subsequent calculations and evaluations.

First, determine how many digits or decimal places the final result should be reported to, then find the next digit to the right. If its value is 0, 1, 2, 3, or 4, drop that digit and all subsequent digits. If the value is 6, 7, 8, or 9, increase the preceding digit (the last one that will be reported) by 1, and then drop all subsequent digits and decimal places from the number. If the last digit or decimal place to be reported is a 9, it will increase to a 0 and the next digit or decimal place to the left will be increased by 1. Follow the same rule for any additional 9s.

If the value is 5, then there are two possible rules to follow. Under standard rounding rules, the preceding digit or decimal place should be increased by one, with the same rules applying as if it were greater than 5. This is called the round-up rule. The alternate rule is that if the value is a 5, the last digit or decimal place to be reported should be left as-is if it is an even number and increased by 1 if it is an odd number. This is called the round-to-even rule.

Examples:

1.34 rounded to one decimal place would round to 1.3.

1.995 rounded to two decimal places would round to 2.00.

134 rounded to the 10’s place would round to 130.

1523 rounded to the 100’s place would round to 1500.

A note about spreadsheets: Spreadsheet programs (e.g., Excel) allow for the easy presentation and numerical evaluation of large quantities of data, which makes them very useful in a wide range of applications, including report preparation. If using Excel to perform rounding functions, there are two limitations the user should be aware of. First, Excel always rounds up and does not have a simple built-in round-to-even function. Second, Excel does not have a rounding function for integers (i.e., numbers cannot be rounded to the nearest 10s or 100s place) and puts trailing 0s in place of sig figs.

Examples:

1.25 in Excel will round to 1.3, as opposed to 1.2 by using the round-to-even rule.

1392 cannot be rounded any further in Excel, whereas it can be presented as 1390 by rounding to the nearest 10s place and as 1400 by rounding to the nearest 100s place.

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Sediment Testing Interference Series – Part IV

Specific Types of Interferences and Solutions (continued from Part III)

Toxicological Interferences

Whereas chemical testing is used to determine the concentration of target contaminants in a sediment sample, toxicological testing is used to determine the effects of the sediment on the survival and development of multiple representative species. Since the organisms will be affected by the sediment as a whole, and since the material is typically a mixture of sand, silt, and clay with numerous chemical contaminants present, it may be difficult or impossible to determine the exact cause of high mortality or abnormal development. Several interferences, or confounding factors, have been identified, however, and are described below.

Ammonia

Above certain levels, ammonia is highly toxic to most marine organisms. It is also a non-persistent toxicant in the environment, and procedures have been developed to help reduce ammonia to more tolerable levels for the test organisms. These procedures were initially developed for the more sensitive benthic species, but, with EPA approval, can also be applied to other organisms under certain circumstances.

Total Organic Carbon (TOC) Availability and Quality

Changes in the nature of TOC in the dredge material may pose limitations to test organism survival. Organic compounds can change over time, particularly with changes in temperature, moisture content, and oxygen availability. If the quality of TOC degrades over time, it can affect the survival of certain species, e.g., for Leptocheirus plumulosus due to poor quality food in the sediment. Though the sediment may have low toxicity, survival can be substantially reduced. Providing a small amount of food for the organisms during analysis alleviates the problem and allows for a more accurate determination of toxicity.

Salinity

Marine organisms are sensitive to the salinity of the test sediment. Sediment collected from far upstream or from terrestrial locations will often have much lower saline levels than sediment from offshore locations and could cause stress to the test organisms and increase mortality. An acclimatization period for the sediment, typically lasting a few days to 3 weeks, will gradually expose the sediment to saline. Once the acclimatization is completed, the test organisms can be added and testing can commence.

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Sediment Testing Interference Series – Part III

Specific Types of Interferences and Solutions (continued from Part II)

Organic Interferences

Organic compounds (PAHs, pesticides, PCBs) are typically measured by either mass spectroscopy or retention time. Because of a preliminary extraction procedure, salt does not interfere in the analysis of organic compounds, but sediment can still be affected by matrix interferences in a number of ways.

  • Complex organic molecules can bind together or degrade over time and form non-target compounds.
  • New contaminants that have the same characteristic mass or retention time as the target analyte can be introduced into the environment (from leaking vessels or industrial runoff, for example).
  • Sediment will likely settle into separate layers, leading to different chemical and physical characteristics in each layer. The sediment will require thorough homogenization prior to analysis to ensure that it is representative of the site.

There are a variety of solutions to eliminate or minimize potential interferences during preparation and analysis.

  • Commercially available cartridges are used to remove or “clean up” interfering (non-target) compounds for most organic analytical groups, such as PAHs, pesticides, and PCBs.
  • Using more-sensitive equipment can help distinguish target compounds from interfering compounds. High resolution mass spectroscopy (HRMS) is often used for testing parameters such as dioxins and PCBs to narrowly target specific compounds. Results from these procedures will often be much more sensitive than when ordinary mass spectrometer tests are applied, but these procedures are also considerably more costly. As one example, the cost for analyzing PCBs by gas chromatography is around $200 per sample, but for HRMS it is around $800 per sample.
  • Different types of detectors are available for different analyses. For example, an electron capture detector is useful for pesticide and PCB analysis.
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