Vadose Zone Monitoring Research Articles

AUTOMATIC SAMPLING OF PERCHED WATER FROM VADOSE ZONE SHALLOW WELLS

Since the late 1970s there has been increased interest in understanding groundwater movement and solutetransport in the vadose zone. While it is widely recognized that the potential for significant lateral flow exists as waterperches above impeding layers in the vadose zone, conducting meaningful research on this phenomenon requires controlof land management over large areas. A 7500-ha holding available to the Tennessee Agricultural Experiment Station atthe Ames Plantation in West Tennessee provides such an opportunity for extensive vadose zone monitoring over largeareas. In 1991 an interdisciplinary team of researchers at The University of Tennessee began developing a researchfacility in a 994-ha agricultural watershed to monitor off-site movement of agricultural chemicals. A 10-ha no-tillage testsite was equipped with a centrally located 0.4-ha test plot and a monitoring system to characterize surface andsubsurface hydrology. Shallow wells to collect perched water, with screens at the loess-paleosol interface (1.8 to 2.8 mbeneath the soil surface), were installed at 23 locations on concentric circles with radii of 45, 60, 90, and 150 m from thecenter of the 0.4-ha test plot.<br><br>Potassium bromide was surface applied on 9 March 1993 to the 0.4-ha test plot at the rate of 300 kg/ha of Br. Datafrom shallow wells at the Ames Plantation Water Quality Project indicated extensive lateral movement of water in thevadose zone. Based on the spatial distribution of the shallow wells that yielded bromide, 17 additional shallow wells wereinstalled in March 1995 to more accurately characterize water movement at the loess-paleosol interface. An automaticsampling system was installed to collect samples from the 17 new wells as well as from four of the original wells. Thesampling system uses a liquid level switch and a datalogger to open a solenoid valve allowing vacuum from supply tanksto extract the sample from the well into sample collection jugs and to record the time the samples are extracted. Thesampling system is working well and is easily maintained by the field technician.

Handbook of Vadose Zone Characterization and Monitoring

Journal of Environmental QualityVolume 25, Issue 4 p. 925-925 Book Review Handbook of Vadose Zone Characterization and Monitoring Edited by L.G. Wilson, Lorne G. Everett, and Stephen J. Cullen, Lewis Publishers/CRC Press, 2000 Corporate Blvd. NW, Boca Raton, FL 33431. 1995. 730 p. ISBN 0-87271-610-8 Jim McCord, Jim McCord Geohydrology Department, Sandia National Laboratories, Albuquerque, NM, 87185-1324Search for more papers by this author Jim McCord, Jim McCord Geohydrology Department, Sandia National Laboratories, Albuquerque, NM, 87185-1324Search for more papers by this author First published: 01 July 1996 https://doi.org/10.2134/jeq1996.00472425002500040041xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume25, Issue4July‐August 1996Pages 925-925 RelatedInformation

Vadose Zone Monitoring: Experiences and Trends in the United States

AbstractThe vadose zone is the portion of the geologic profile above a perennial aquifer. Inclusion of mandatory vadose zone monitoring techniques as an approach to aquifer protect ion was first proposed under the Resource Conservation and Recovery Act in the United States in 1978 and has since received increasing acceptance at federal and stale levels. The goals of a vadose zone characterization and monitoring effort are to establish background conditions, identify contaminant transport pathways, identify the extent and degree of existing contamination, establish the basis for monitoring network design, measure the parameters needed in a risk assessment, and provide detection of contaminant migration toward ground water resources. The benefits of vadose zone monitoring include early warning of contaminant migration, potential reduction of ground water monitoring efforts, reduction of contaminant spreading and volume, and reduced time and cost of remediation once a contaminant release occurs. Vadose zone characterization and monitoring techniques should be considered as critical hydrologic tools in the prevention of ground water resource degradation.

A Systematic Approach to Designing a Multiphase Unsaturated Zone Monitoring Network

AbstractA systematic approach is presented for the design of a multiphase vadose zone monitoring system recognizing that, as in ground water monitoring system design, complete subsurface coverage is not practical. The approach includes identification and prioritization of vulnerable areas: select ion of cost‐effective indirect monitoring methods that will provide early warning of contaminant migration: selection of direct monitoring methods for diagnostic confirmation; identification of background monitoring locations; and identification of an appropriate temporal monitoring plan. An example of a monitoring system designed for a solid waste landfill is presented and utilized to illustrate the approach and provide details of system implementation. The example design described incorporates the use of neutron moisture probes deployed in both vertical and horizontal access tubes beneath the lcachate recovery collection system of the landfill. Early warning of gaseous phase contaminant migration is monitored utilizing whole‐air active soil gas sampling points deployed in gravel‐ filled trenches beneath the subgrade. Diagnostic confirmation of contaminant migration is provided utilizing pore‐ liquid samplers. Conservative tracers can be used to distinguish between chemical species released by a landfill from those attributable to other (e.g. off‐site) sources or present naturally in the subsurface. A discussion of background monitoring point location is also presented.

Hazardous waste storage, disposal, remediation, and closure

Hazardous waste storage, disposal, remediation, and closure

EPA's Approach to Vadose Zone Monitoring at RCRA Facilities

AbstractThe U.S. Environmental Protection Agency (EPA) recently proposed to amend federal regulations to require vadose zone monitoring at certain hazardous waste facilities. To support this proposal, EPA evaluated previous policy on vadose zone monitoring and examined advances in vadose zone monitoring technology. Changes in EPA vadose zone monitoring policy were driven by demonstrated advances in the available monitoring technology and improvements in understanding of vadose zone processes/When used under the appropriate conditions, currently available direct and indirect monitoring methods can effectively detect contamination that may leak from hazardous waste facilities into the vadose zone. Direct techniques examined include soil‐core monitoring and soil‐pore liquid monitoring. Indirect techniques examined include soil‐gas monitoring, neutron moderation, complex resistivity, ground‐penetrating radar, and electrical resistivity. Properly designed vadose zone monitoring networks can act as a complement to saturated zone monitoring networks at numerous hazardous waste facilities. At certain facilities, particularly those in arid climates where the saturated zone is relatively deep, effective vadose zone monitoring may allow a reduction in the scope of saturated zone monitoring programs.

Reply to the preceding Discussion by Michael A. Williams of “Vadose Zone Monitoring with the Neutron Moisture Probe.”

Groundwater Monitoring & RemediationVolume 13, Issue 1 p. 161-162 Reply to the preceding Discussion by Michael A. Williams of “Vadose Zone Monitoring with the Neutron Moisture Probe.” John H. Kramer, John H. Kramer Vadose Zone Monitoring Laboratory, Institute for Crustal Studies, UCSB, CA 93106–1100Search for more papers by this author John H. Kramer, John H. Kramer Vadose Zone Monitoring Laboratory, Institute for Crustal Studies, UCSB, CA 93106–1100Search for more papers by this author First published: February 1993 https://doi.org/10.1111/j.1745-6592.1993.tb00434.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue1February 1993Pages 161-162 RelatedInformation

Vadose Zone Monitoring with the Neutron Moisture Probe

AbstractThe neutron moisture probe is widely applicable to vadose zone monitoring problems which require measuring variable moisture contents. Neutron data are proportional to hydrogen density (modified by local chemistry) and sensitive to wetting fronts as well as changing volumes of hydrocarbon liquids. They cannot, however, be used to confirm contaminant chemistry, nor to detect steady‐state flow. Neutron data are amenable to statistical analysis, providing a measure of the significance of data variations. Detection of incipient moisture changes at numerous monitoring locations is more practical using raw neutron data than data calibrated for moisture content because calibrations suffer from uncertainties associated with soil heterogeneities. When properly applied, the neutron probe is an effective monitoring tool as illustrated by three example applications described in this paper: (1) neutron moisture logs are used to detect subtle lithologic changes and identify monitoring horizons; (2) sequential neutron data are used to track induced saturation at a soil flushing pilot study; and (3) neutron logs from a horizontal access tube beneath a waste facility are used to pinpoint moisture anomalies.

Class III Landfill Monitoring in Active Fault Regime

A Class III landfill in the San Joaquin Valley area has been investigated in connection with regulatory permitting requirements. The hydrogeologic regime is dominated by recharge from the nearby Kern River. A review of subsurface data for the nearby Kern Bluff oil field shows a north-side-up fault that forms a structural trap on the north side of the field. This fault is herein named the Kern Bluff fault. Trenching within the landfill site shows that the fault transects the site. Displacement continues to the surface, with modern soils displaced against the Miocene-Pliocene Kern River Formation. Limited monitoring well data indicate that the fault divides the groundwater beneath the site into two aquifers. Vadose zone monitoring data indicate limited migration of contaminants within the Kern River Formation, but the contaminants have not reached the water table.

ASTM Subcommittee develops standards

Under ASTM Committee D‐18 on Soil and Rock, Subcommittee D‐18.21 on Ground Water and Vadose Zone Investigations is developing standards for methods and materials used in the conduct of ground water and vadose zone investigations and monitoring. The Subcommittee is chaired by David M. Nielsen of Blasland, Bouck, and Lee, Inc., Westerville, Ohio; vice‐chairman is Ivan Johnson of A. Ivan Johnson, Inc., Arvada, Colo.; and secretary is Joseph D. Ritchey of Heritage Remediation/Engineering, Inc., Toledo, Ohio.

Equipment Decontamination Procedures for Ground Water and Vadose Zone Monitoring Programs: Status and Prospects

AbstractA major portion of the work effort and, therefore, the money spent during investigations of ground water and the vadose zone at hazardous waste sites is associated with collecting chemical data. To that end, effective decontamination of reusable drilling equipment, sampling apparatus, and tools is critical to the credibility of chemical data. Samples representative of the site under study are essential.Several state and federal regulatory agencies have established guidelines for procedures that should be considered when developing decontamination protocols. These agencies were contacted and asked to furnish copies of their decontamination guidelines. The information received was reviewed, and comparisons were made to assess the status of standards of decontamination practices for ground water and vadose zone monitoring programs at hazardous waste sites. Summaries of a variety of decontamination protocols were prepared. From this review, it is apparent that there is a need to standardize, to the extent possible, procedures for the field decontamination of equipment.Two ASTM Subcommittees, D18.14 on Waste Management and D18.21 on Ground Water and Vadose Zone Monitoring, are currently working on developing standards for decontamination procedures. They, in cooperation with state and federal agencies and other interested technical groups, will develop standards for the field decontamination of equipment used to study ground water and the vadose zone.

Standards for groundwater monitoring

The American Society of Testing and Materials Subcommittee D‐18.21 on Groundwater Monitoring is charged with developing standards for methods and materials used in the conduct of groundwater and vadose zone monitoring investigations. The subcommittee, which is part of ASTM Committee D‐18 on Soil and Rock, is chaired by David M. Nielsen of Westerville, Ohio; vice‐chairman is Ivan Johnson of Arvada, Colo., and secretary is Joseph D. Ritchey of Keck Consulting Services, Inc.Sections within the subcommittee have been formed to address a variety of narrower subject areas, including surface and borehole geophysics, Wayne Saunders, chairman vadose zone monitoring, Lome Everett, chairman monitoring‐well drilling and soil sampling practices, Robert Pentergast, chairman determination of hydrogeologic parameters, Doug Bedinger, chairman monitoring‐well design and construction, Martin Sara, chairman monitoring‐well maintenance, rehabilitation, and abandonment, Steven Nacht, chairman groundwater sample collection, handling, and field analysis, Beth Martin, chairman design and analysis of hydrogeologic data systems, Roger Henning, chairman special problems of monitoring in karst terrains, James Quinlan, chairman groundwater modeling, J . D. Ritchey, chairman

Tensiometer and pore water sampler for vadose zone monitoring : Morrison, R D; Szecsody, J E Soil SciV144, N5, Nov 1987, P367–372

Tensiometer and pore water sampler for vadose zone monitoring : Morrison, R D; Szecsody, J E Soil SciV144, N5, Nov 1987, P367–372

Vadose Zone Monitoring: An Early Warning System

AbstractCurrently, vadose zone monitoring is required under the Resource Conservation and Recovery Act (RCRA) only at land treatment facilities. Contaminant leak detection through ground water monitoring is very important, but it is considered to be after the fact. Remedial action costs can be reduced considerably by monitoring the vadose zone for compounds that exhibit high rates of movement. Volatile organic compounds (VOCs) exhibit this property and are present at many municipal landfills, recycling facilities, and treatment storage and disposal facilities (TSDFs). Through the authors’personal experience, it has been noted that gaseous phase transport of VOCs through the vadose zone is at least an order of magnitude greater than advective transport of VOCs in ground water. Therefore, VOCs in soil gas are an effective early warning leak detection parameter. Downward movement of leachate can be intercepted by porous cup lysimeters. Attenuation in the vadose zone slows the apparent movement of contaminants; however, it is only a matter of time before leachate reaches the water table. The authors believe that soil‐gas and pore‐water monitoring should and eventually will be required at all RCRA sites. If vadose zone monitoring becomes an additional requirement under RCRA, both the facility owner and the taxpayer will benefit. During the interim, facility owners can benefit by employing vadose zone monitoring techniques coupled with either qualitative or quantitative chemical analyses.

Vadose Zone Monitoring for Hazardous Waste Sites.

This book describes the applicability of vadose zone monitoring techniques to hazardous waste site investigations. More than 70 different sampling and nonsampling vadose zone monitoring techniques are described in terms of their advantages and disadvantages. Physical, chemical, geologic, topographic, geohydrologic, and climatic constraints for vadose zone monitoring are quantitatively determined. Vadose zone monitoring techniques are categorized for premonitoring, active, and postclosure site assessments. Waste disposal methods are categorized for piles, landfills, impoundments, and land treatment. Conceptual vadose zone monitoring approaches are developed for specific waste disposal method categories.

Factors Requiring Resolution in Installing Vadose Zone Monitoring Systems

AbstractIncreasingly, regulations by federal, state and local agencies are being developed that require the installation of vadose zone monitoring systems for hazardous chemical facilities in addition to, or in lieu of, conventional ground water monitoring wells. Compared to a ground water monitoring approach, vadose zone monitoring systems may permit earlier detection of chemical leakage and less costly cleanup of contamination. The effective use of vadose zone monitoring systems in detecting contamination depends on many factors. Without proper consideration of these factors, a vadose zone monitoring system may not give as high a level of reliability as a ground water monitoring system.Major factors to consider in installing a vadose zone monitoring system are: type of instrument to use, number of instruments, depth and location of instruments, and frequency of monitoring. Means to evaluate these factors in a comprehensive fashion have been lacking. Based on recent experience in installing and operating vadose zone monitoring systems, criteria and methods useful in resolving the preceding factors have been developed. Types of instruments can be classified as either direct (lysimeter, vapor probe) or indirect (tensiometer, conductivity probe). A combination of the two is needed for reliability. The depth, location and number of instruments depend on the geometry of the facility, the number and size of likely contaminant leakage points in engineered barriers, properties of the material being monitored, the effective radius of monitoring for each instrument, vadose zone properties, and types of remedial actions that are available. The freqency of monitoring largely depends on the rate of movement of the contaminant. Evaluating the preceding factors requires some level of modeling and preliminary field testing.

Book Review: VADOSE ZONE MONITORING FOR HAZARDOUS WASTE SITES. By L. G. Everett, L. G. Wilson, E. W. Hoylman. Pollution Technology Review No. 112. Noyes Data Corporation, Park Ridge, New Jersey (1984): 251 pp. Price $36. Reviewed by Dr Lewis Clark, Head of Pollutant Pathways, Water Research Centre, Medmenham, U.K

Book Review: VADOSE ZONE MONITORING FOR HAZARDOUS WASTE SITES. By L. G. Everett, L. G. Wilson, E. W. Hoylman. Pollution Technology Review No. 112. Noyes Data Corporation, Park Ridge, New Jersey (1984): 251 pp. Price $36. Reviewed by Dr Lewis Clark, Head of Pollutant Pathways, Water Research Centre, Medmenham, U.K

Constraints and Categories of Vadose Zone Monitoring Devices

AbstractTraditional monitoring methods using chemical analysis of ground water samples to detect pollutant migration are being superseded or used in conjunction with innovative approaches. A need to detect pollutants before they reach the water table has drawn interest to vadose (unsaturated) zone monitoring and brought together hydrogeologists, soil scientists and agricultural engineers who have been working on this subject for years.Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility.Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site‐specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy; degree of operational complexity; direct versus indirect methods; applicability to alternate media; effect on flow regime; and effect of hazardous waste on sampling or measurements. Application of the selection criteria is discussed in Everett et al. (1982a).

Vadose Zone Monitoring Concepts for Hazardous Waste Sites

ABSTRACTThe implementation of the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) may be enhanced by wider applications of vadose zone monitoring. More than 50 different vadose zone monitoring techniques are referenced. Fourteen different criteria are established for selecting alternative vadose zone monitoring methods. These monitoring methods are categorized according to premonitoring techniques, sampling methods and nonsampling methods which could be applied in the vadose zone. Two conceptual cases are presented covering vadose zone monitoring at a hazardous waste disposal impoundment. The rationale for the monitoring program at a new impoundment and for an active impoundment is presented. The material constitutes the first phase of a vadose zone monitoring manual.