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Soil and Sediment Sampling Methods

Abstract:

Research has been initiated to meet EPA's initiative addressing the fundamental issues concerning contaminated sediments, namely: (1) adequately estimating risks; (2) developing and evaluating risk management options; (3) and monitoring sites before, during, and after remedy implementation. Research to improve the collection of undisturbed surface sediments so that the effects of recent disturbances (such as dredging activities) can be identified and quantified is underway. A prototype undisturbed surface sediment sampler has been created and is undergoing field testing at contaminated sediment sites. Research to remotely identify surface sediments (i.e., the fluff layer or liquid mud) is being initiated.

A new area of research currently being initiated is related to asbestos determination and separation from soils. EPA's Asbestos Research Plan identified areas where knowledge and understanding of asbestos could be improved. Within the plan, one area of needed research was in fiber definition and source characterization. An asbestos workgroup was formed to prioritize the exposure research support for the Asbestos Research Plan. Among the high priority research areas were the needs for: (1) standard soil sampling and sample preparation methods and (2) a standard bulk sample (e.g., soil, asbestos containing materials, etc.) grinding technique. The objective of this research effort is to evaluate (and develop, if necessary) a method for the effective and efficient separation of asbestos fibers from soils while maintaining the integrity of the asbestos fibers (i.e., without fiber length reduction) so that the true characteristics and quantity of asbestos in the soils can be determined.

Brownfields are real property of which the expansion, redevelopment, or reuse may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. Brownfields redevelopment is a priority at EPA. Current investigations into the risk to human health associated with Brownfield redevelopment may be overlooking an important exposure pathway as a result of vapor intrusion into buildings. Persons inhabiting or employed in new or existing structures built over volatile organic compound (VOC)-contaminated ground water, or soil, may be exposed to harmful vapors emanating from the ground beneath them. A research program is being initiated that will standardize soil gas sampling techniques, examine spatial and temporal variations in vapor concentrations as they relate to vapor intrusion, and look for surrogate sampling possibilities that may reduce the need for in-home sampling.

Under this task, improved sampling approaches and devices will be developed for characterizing the concentration of VOCs in soils. Current approaches and devices used today can lose up to 99% of the VOCs present in the sample due to inherent weaknesses in the device and improper/inadequate collection techniques. This error generally causes decision makers to markedly underestimate the soil VOC concentrations and, therefore, to greatly underestimate the ecological and human health risks associated with these compounds. To improve the sampling of VOC-contaminated soils, research will be conducted in four major areas where VOCs can be lost, namely, during sample collection, handling, storage, and preservation with the goal of eliminating or greatly reducing the VOC losses.

Objective:

The overall objective of this task is to provide EPA with improved state-of-the-science guidance, strategies, and techniques to more accurately and effectively collect environmental samples. Under this umbrella objective, research is being conducted to: (a) identify and collect undisturbed surface sediments so that the effects of recent depositional events (e.g., flooding or dredging) can clearly be delineated as to their influence on the contamination concentrations present downstream (or where the sediments are deposited); (b) determine an effective method to effectively and efficiently separate asbestos in soils from the rest of the soil matrix while maintaining the integrity (i.e., no fiber size reduction) of the asbestos fibers; (c) support Brownfields vapor intrusion modeling efforts by providing improved soil vapor/gas sampling techniques, spatial (lateral and vertical) and temporal (diurnal, seasonal, and meteorologically-influenced) variability data, and surrogate sampling possibilities; and (d) reduce/minimize the loss of VOCs during sample collection, handling, and preservation.

Progress to Date:

A prototype undisturbed surface sediment (USS) sampler has been created and tested in the laboratory and at one field site. During the USS sampler testing, each sampling event was filmed to provide visual evidence of the amount of surface disturbance that occurred when the USS sampler and the Ponar sampler (a very commonly used sediment sampling device) came into contact with the sediments. An EPA project report has been prepared and published on the initial testing of the USS sampler. Slight modifications to the design had to be made after each testing to accommodate the differences in sediment types encountered in each situation. A contaminated site has been identified for testing of the second version of the USS sampler. Sampling should occur in December 2005 or an alternative site may be necessary.

The contract for the "Separation and Isolation of Asbestos from Soils" has been let. Initial testing of selected soils indicates that they are asbestos-free and will make a good base matrix for asbestos spiking. Asbestos, both amphibole and serpentine forms, has been obtained and is being characterized.

A contract is currently being competitively bid upon for the initial work in the Brownfields vapor intrusions/Superfund collaborative effort. This contract will be for the standardization of a soil gas collection method. Comparisons with micro-purge techniques will be made concurrently with the macro-purge "standard" soil gas technique.

Several studies are ongoing for the VOC-contaminated soil. A sample preservation study has been conducted and results are currently being processed. Testing of an innovative sampling device continues and results are currently being processed. A final field site is being sought for further testing. Instrumentation has been procured and initial testing has been completed for the study of effects of soil disturbance on VOC emissions from aged, contaminated soil, the examination of the micro-purge soil gas techniques, and sample compositing techniques. Field sampling has occurred at two Superfund sites. Results are currently being processed and additional sites are being sought for further testing.

Relevance/Significance/Impact:

These activities support EPA’s first strategic research goal (as defined in the 2001 EPA Strategic Research Plan) by maintaining a balanced program of problem-driven research.

Contaminated sediment research has been identified directly by EPA as a major area of concern. In addition, the States are interested in contaminated sediments because they impact designated uses established in state water quality standards. EPA is interested in contaminated sediments because it has been charged to conduct a comprehensive national survey of data regarding the quality of aquatic sediments in the U.S. and the methods and techniques developed can directly affect and benefit the data gathering efforts. To respond to its needs, EPA has established a contaminated sediments research program. The current and proposed future studies on the collection of undisturbed surface sediments support many of the high priority research priorities as identified by EPA. Additionally, meetings with the U.S. Army Corps of Engineers and U.S. Navy (held in September 2005) confirmed the need for the ongoing research effort to develop tools and techniques to collect undisturbed surface sediments (e.g., fluff or liquid mud). As a result of ongoing and planned research efforts, EPA will provide sampling tools that will allow for the location and collection of undisturbed surface sediments that can, in turn, be subsampled at varying thicknesses. Remedial Project Managers (RPMs) can use the USS sampler to identify any downstream impacts due to the resuspension of contaminated sediments from dredging, snow melt flooding, or large storm events. If impacts are found, the RPMs can reevaluate their remediation plans, apply more protective measures or barriers (e.g., silt screens), or halt dredging operations to protect the environment.

EPA looked at the state of the science on asbestos and developed a series of science questions that are presented in EPA's Asbestos Research Plan. Within the plan, one area of needed research was in fiber definition and source characterization. In particular, a research need was identified to “Develop a standard method for asbestos analysis in soil.” An asbestos workgroup was formed to prioritize the exposure research support for the Asbestos Research Plan. Among the high priority research areas were the needs for: (1) standard soil sampling and sample preparation methods and (2) a standard bulk sample (e.g., soil, asbestos containing materials, etc.) grinding technique. The current research effort will deal with a portion of the first of these two high priority research needs. The initial objective of this research effort is to evaluate (and develop, if necessary) a method for the effective and efficient separation of asbestos fibers from soils while maintaining the integrity of the asbestos fibers (i.e., without fiber length reduction) so that the true characteristics and quantity of asbestos in the soils can be determined. By providing a method to separate the asbestos fibers intact, risk assessors, RPMs, and modelers will have accurate data from which to assess the potential exposure and extent of potential harm to living organisms that may occur due to the release of asbestos fibers.

Vapor intrusion is a research priority identified in both the 2003 Contaminated Sites and RCRA multi-year plans by EPA. In the Contaminated Sites Multi-Year plan - Appendix D, EPA specifically requested assistance in this area under the GW-4 Goal of "Emerging Issues" specifically stating it needs "research on improved methods for assessing migration of contaminants from ground water to indoor air. This includes improved site characterization techniques, model verification studies, and improved guidelines for use of models." Similarly, in the RCRA Multi-Year plan, EPA identified the research need that stated " develop or evaluate innovative characterization technologies that allow for quicker and more accurate assessment of contaminated sites, especially for the vapor intrusion pathway." The proposed research program in this area is designed to help resolve these issues. In FY05, the Brownfields Program expanded becaming highly interested in the vapor intrusion issues as it related to potential Brownfields site redevelopment. Current investigations into the risk to human health associated with Brownfield redevelopment may be overlooking an important exposure pathway as a result of vapor intrusion into buildings. Persons inhabiting or employed in new or existing structures built over volatile organic compound (VOC)-contaminated ground water, or soil, may be exposed to harmful vapors emanating from the ground beneath them. A vapor intrusion research program is being initiated that will standardize soil gas sampling techniques, examine spatial and temporal variations in vapor concentrations as they relate to vapor intrusion, and look for surrogate sampling possibilities that may reduce the need for in-home sampling. Results from this research program will provide tools, methods, and data to support modeling efforts so that the true potential and true risks of exposure to these harmful vapors can be determined. With this information in hand, the Agency can implement better remedial strategies to protect human health and the environment.

Research conducted under this task also directly supports EPA, by providing improved methods, techniques, and tools to reduce or eliminate the losses of contaminants that occur during sampling. This research program, addressing the issue of eliminating errors (i.e., losses) that occur during the sampling and analysis of soil samples contaminated with VOCs, is reviewed annually during the Waste Progress Review held in Washington. It is through these continual reviews that EPA ensures that it meets the nation's wants, needs, expectations, and requirements, now and in the future. Current sampling techniques for VOC-contaminated soils and sediments may result in losses of up to 99% of the VOCs. These unknown and unquantified losses result in data being given to decision makers and regulators that may only represent part of the contamination (i.e., some percentage less than the actual contaminant concentrations) present at a given site. In turn, the decision makers then decide whether remediation is necessary based on negatively biased results that can lead to leaving significant concentrations of VOCs in the soils. Each experiment under this task addresses a unique aspect of the overall sampling problem. When these studies are completed, they will provide a complete picture on the best methods and techniques to collect and analyze VOCs in the soil matrix. With the improved data which allows for the collection of more accurate and representative samples from the field, decision makers will be able to make much improved decisions based on better facts about the extent of contamination at a contaminated site.

Approach:

It should be noted that the major difficulty to date with this task has been identifying and obtaining access to Superfund or other contaminated sites with the characteristics that are desirable (or at least usable) for our studies. These characteristics for the sediment sampling work include: different sedimentary environments (e.g., lakes, rivers, bays, harbors) with relatively shallow water to sediment depths, relatively clear water, and contamination in the low mg/kg to mid ug/kg concentrations. For the Brownfields vapor intrusion, conditions would include: long-term access to homes or near home locations for sampling, shallow depth to ground water (3-5 m below ground surface), and contamination of VOCs in the low mg/kg to mid ug/kg concentrations. For the VOC in soils work, conditions include: relatively shallow depth to contamination (3-5 m or less below ground surface); VOC concentrations in the low mg/kg to mid ug/kg levels; minimal rocks, pebbles, and cobbles; and minimal contamination by other inorganic and organic compounds.

FY06 Activities

Investigations to improve the collection of undisturbed surface sediments so that the effects of recent disturbances (such as dredging activities) can be identified and quantified will continue in FY06 with sampling using the second (modified from the original version) version of the USS sampler. Sampling is currently planned for December 3-9, 2005, at the New Bedford Harbor Superfund site in New Bedford, MA, which has varying levels of PCB contamination. If weather conditions do not permit the planned sampling trip, either (a) sampling will occur in late spring at New Bedford Harbor or (b) an alternate site will be sought in warmer climates. Sampling in a different sedimentary environment from the initial trial of the USS sampler (a fresh water lake) is required to test the robustness of the sampler.

In conjunction with the USS sampler testing, initial investigations are underway to remotely detect the presence of the sediment surface fluff layer (or fluid mud) so that sampling efforts will not be wasted or made in areas where the fluff layer does not exist. Currently, researchers at the U.S. Army Corps of Engineers-Waterways Experiment Station (USACOE-WES) in Vicksburg, MS, are investigating the use of the DensiTune silt density probe for the determination of the presence and location of fluid mud associated with dredged channel refill and navigable depth. Their efforts have looked at fluid mud layers greater than 6 inches in depth. No effort has been made on a finer scale nor in looking at non-navigable channel usage of the probe. Discussions are ongoing with the USACOE-WES about a collaborative research effort to "fine-tune" the DensiTune probe to detect thin sediment fluff layers and using the USS sampler to confirm the probe results and collect the required surface sediment layers. An IAG with USACOE-WES is anticipated.

Research was initiated and a contract let in late FY05 to address the separation and isolation of asbestos in soils. This research will continue looking at an effervescence-based extraction technique. Base soils and bentonite clay have been provided to the contractor so initial characterization of the soils and clay to determine if they are asbestos-free will begin. If asbestos-free, testing of the extraction technique will begin on the pure bentonite clay sample (assumed to be a difficult matrix). If successful, soil spiking/testing will be initiated. Should the effervescence-based extraction technique fail to maintain the integrity of the asbestos fibers, an alternate separatory method will be sought.

It is anticipated that research on the creation of a standard bulk sample preparatory technique (i.e., a technique that will maintain asbestos fiber integrity while separating the asbestos from a hard, compacted/cemented/solid material, such as rocks, wall boards, etc.) will begin in late FY06.

An initial vapor intrusion/indoor air research effort has been funded through the Brownfields Office (OCBR) to establish a single standardized method for the collection of soil vapor/gas samples. A contract is in the process of being competed to support this research effort. This research effort will examine the variables associated with soil gas sampling (e.g., purging, sample size, and sampling flow rates) as well as compare the standard method (a.k.a. macro-purge method) to a micro-purge sampling technique.

Several experiments examining means to control the losses of VOCs during sampling, handling, and preservation continue toward completion. These experiments include: a sample preservation study; assessing the release of VOCs due to sample disturbance; examining the use of micro-purge soil gas techniques (done in conjunction with the vapor intrusion effort); sample compositing; and the testing of the prototype soil sampler to minimize the loss of VOCs during sampling. The sample preservation and sample compositing study should be completed this FY. The sample disturbance, micro-purge soil gas technique, and prototype sampler testing require sampling at one more Superfund site; therefore, it may be completed late this FY with reporting next FY depending on access to a suitable site.

A comparison study of the most common SW-846-based methods for VOC determination will be initiated in FY06 (hopefully). The quality assurance project plan has been revised and approved. The results of this study will provide decision makers with information on which method is most efficient at extracting and quantifying VOCs and thus provide the most accurate data on VOC concentrations at a site. This study has been delayed due to the unavailability of the instrumentation commercially for the third most commonly used SW-846 method (Method 8261). We are also in the process of acquiring a loaner headspace/trap instrument to include in this evaluation.

FY07 Activities

Initial investigations to remotely detect the presence of the sediment surface fluff layer (or fluid mud) using the DensiTune silt density probe and confirmation of the results with the USS sampler will continue in conjunction with the USACOE-WES. Final report preparation should be completed in the fourth quarter of FY07 or early FY08. Additional testing under varying hydrologic and sedimentary regimes may be warranted in late FY07 and throughout FY08.

Research on the development of a standard bulk sample preparatory technique (i.e., a technique that will maintain asbestos fiber integrity while separating the asbestos from a hard, compacted/cemented/solid material, such as rocks, wall boards, etc.) will be initiated (if not done so in late FY06) or continue. Final report preparation should be completed in the fourth quarter of FY07 or early FY08.

Vapor intrusion research effort will be initiated to examine the vertical distribution of VOCs from the ground water surface to the soil surface or subslab interface (and possibly in-home). In conjunction with the vertical distribution of VOC effort, depending upon time and funding, the relationship between subslab vapor concentrations and concentrations from external angular drilling will be investigated in FY07 with a goal of determining if angular drilling can give accurate representation of vapor intrusion concern (so no in-house disturbance is necessary). If long-term site access is obtained, temporal variation studies can begin at the same time as vertical distribution studies.

Determination of the losses and means to control the losses of VOCs during sampling, handling, and preservation continue. These experiments include the completion of the: assessment of the release of VOCs due to sample disturbance; examination of the use of micro-purge soil gas techniques (done in conjunction with the vapor intrusion effort); and the testing of the prototype soil sampler to minimize the loss of VOCs during sampling. Report preparation will begin in late FY07 and continue into FY08.

The comparison study of the most common SW-846-based methods for VOC determination should be completed in FY07 with reporting being completed in late FY07 or early FY08.

FY08 Activities

Initial investigations, with the USACOE-WES, to remotely detect the presence of the sediment surface fluff layer (or fluid mud) using the DensiTune silt density probe and confirmation of the results with the USS sampler should be completed with final report preparation beginning in early FY08. If the DensiTune probe is successful identifying thin sedimentary layers, additional testing under varying hydrologic and sedimentary regimes may be warranted throughout FY08.

Research on the development of a standard bulk sample preparatory technique (i.e., a technique that will maintain asbestos fiber integrity while separating the asbestos from a hard, compacted/cemented/solid material, such as rocks, wall boards, etc.) will continue and be completed in FY08 (if not so in FY07). Final report preparation should be completed in early FY08.

Vapor intrusion research will be initiated on the relationship between subslab vapor concentrations and concentrations from external angular drilling (if not begun in FY07). If long-term site access is obtained, temporal variation studies will be initiated or continue investigation diurnal influences along with research investigating the lateral heterogenity issues and the use of surrogate sampling locations to accurately represent expected subslab VOC concentrations.

Determination of the losses and means to control the losses of VOCs during sampling, handling, and preservation continue with the preparation of individual experiment reports and a guidance document on sampling soils contaminated with VOCs. New areas of research that may be initiated may include studies, such as the influence of down hole vacuum effects during sampler retrieval on VOC concentrations in soil and the influence of organic matter on VOC quantitation.

The report on the comparison study of the most common SW-846-based methods for VOC determination should be completed in FY08, if not done in FY07.

Staffing:

Principal Investigator:

Brian Schumacher, Supervisory Physical Scientist

Other Researchers:

John Zimmerman, Research Physical Scientist

Products:

Abstracts and Oral Presentations:
Schumacher, B.A. and J.H. Zimmerman.Composite Sampling for Soil VOC Analysis.Presented at National Environmental Monitoring Conference, Washington, DC, July 19-22, 2004.
Date Cleared: 4/1/2004 Date Presented: 7/19/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-067

 

Schumacher, B.A. Contaminated Sediment Sampling Methods.Presented at Hazardous Substance Research Centers (HSRC) Workshop, Las Vegas, NV, November 5, 2004.
Date Cleared: 10/28/2004 Date Presented: 11/5/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-200

 

Schumacher, B.A.Quality Assurance Project Plans: A Useless Paper Exercise or Valuable Aid?Presented at 21st Annual National Conference on Managing Quality Systems for Environmental Programs, Phoenix, AZ, April 8-11, 2002.
Date Cleared: 1/29/2002 Date Presented: 4/8/2002 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 02-008

 

Schumacher, B.A., K.E. Snyder, M.M. Minnich, and K. Al-Khafaji.Movement of Trichloroethylene in Caliche.Presented at Annual Soil Science Society of America Meeting, Minneapolis, MN, November 5-9, 2000.
Date Cleared: 5/17/2000 Date Presented: 11/5/2000 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 00-119

 

Schumacher, B.A., and Zimmerman, J.H.Composite Sampling for Soil VOC Analysis.Presented at National Environmental Monitoring Conference, Washington, DC, July 19-20, 2004.
Date Cleared: 7/8/2004 Date Presented: 7/19/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-137

 

Zimmerman, J.H. and B.A. Schumacher.To Purge or Not to Purge? VOC Concentration Changes During Line Volume Purging.Presented at National Environmental Monitoring Conference, Washington, DC, July 19-22, 2004.
Date Cleared: 3/25/2004 Date Presented: 7/19/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-061

 

Zimmerman, J.H., and Schumacher, B.A.To Purge or Not to Purge? VOC Concentration Changes During Line Volume Purging.Presented at National Environmental Monitoring Conference, Washington, DC, July 19-20, 2004.
Date Cleared: 7/13/2004 Date Presented: 7/19/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-141
EPA Proceedings:
Schumacher, B.A. Re-evaluation of Applicability of Agency Sample Holding Times. EPA/600/A-03/209. Biological Advisory Committee - Research Methods Symposium, Newport, RI, U.S. Environmental Protection Agency, Washington, DC, October 14-15, 2003.
Date Cleared: 10/23/2003 Date Presented: 10/14/2003 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 03-139
Posters:
Schumacher, B.A., J.H. Zimmerman, and J.M. Nocerino.Advancing Site Characterization and Monitoring Through Client Collaborations.Presented at BOSC Review of Land Research Program, Cincinnati, OH, December 13-15, 2005.
Date Cleared: 11/9/2005 Date Presented: 12/14/2005 Peer Review Category: 3
Tracking ID: NERL-LV-ESD 05-159

 

Zimmerman, J.H.Development of a Systematic Approach to Accurately Measure Trace Levels of VOCs and SVOCs in Soil and Sediment With High Moisture Content.Presented at EPA 2005 Science Forum, Washington, DC, May 16-18, 2005.
Date Cleared: 2/11/2005 Date Presented: 5/16/2005 Peer Review Category: 3
Tracking ID: nerl-lv-ESD 05-034
Published Reports:
Capri, J., B.A. Schumacher, S. Wanning, E. Smith, J. Zimmerman, and J.D. Vanover, Collection of Undisturbed Surface Sediments, EPA/600/R-05/076, U.S. Environmental Protection Agency, Washington, DC.
Date Cleared: 7/26/2005 Peer Review Category: 4
Tracking ID: NERL-LV-ESD 05-104

 

Capri, J. and B.A. Schumacher, Literature Review and Report: Surface-sediment Sampler Database, EPA/600/R-03/115 (NTIS PB2004-101011), U.S. Environmental Protection Agency, Washington, DC, 2004.
Date Cleared: 9/18/2003 Date Published: 3/9/2004 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 03-128

Hu, Y., J.B. Beach, B.A. Schumacher, and G.L. Robertson, Evaluating Commercially Available Dermal Wipes, Cotton Suites, and Alternative Urinary Collection Materials for Pesticide Sampling From Infants, EPA/600/R-04/087, U.S. Environmental Protection Agency, Washington, DC, 2004.
Date Cleared: 8/4/2004 Date Published: 1/10/2005 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 04-153

 

Schumacher, B.A. Methods for the Determination of Total Organic Carbon (TOC) in Soils and Sediments, EPA/600/R-02/069 (NTIS PB2003-100822), U.S. Environmental Protection Agency, Washington, DC, 2002.
Date Cleared: 7/17/2002 Date Published: 8/24/2002 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 02-119

 

Schumacher, B.A., M.M. Minnich, J.H. Zimmerman, and J. Blasdell, Integrity of VOA-Vial Seals, EPA/600/R-00/066 (NTIS PB2001-101547), U.S. Environmental Protection Agency, Washington, DC, 2000.
Date Cleared: 7/25/2000 Date Published: 9/15/2000 Peer Review Category: 4
Tracking ID: nerl-lv-ESD 00-138

 

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