Gail Heath

Spatial focusing of electrical resistivity surveys considering geologic and hydrologic layering

Electrical resistivity tomography ERT has shown great promise for monitoring transient hydrologic processes. One advantage of ERT under those conditions is the ability of a user to tailor the spatial sensitivity of an ERT survey through selection of electrode locations and electrode combinations. Recent research has shown that quadripoles can be selected in a manner that improves the independent inversion of ERT data. Our ulti

Autonomous Monitoring of Fluid Movement Using 3-D Electrical Resistivity Tomography

The electrical resistivity tomography method (ERT) is seeing increasing use in long-term monitoring. Applications might include monitoring of advanced remediation methods, vadose zone fluid-flow monitoring, and monitoring below tanks at the Hanford reservation. For this method to be cost effective, future systems will need to be highly automated. This paper compares different strategies for collecting three-dimensional (3-D) data sets. We discuss the critical design aspects of the system and the importance of using integrated hardware for data collection, and software for data interpretation. An autonomous acquisition system was used to monitor a field experiment at the Idaho National Engineering and Environmental Laboratory. The system was successful at collecting data that were used to monitor infiltration of water into interbedded sediment and basalt layers. The results showed the advantages of autonomous systems for collecting data, and the need for robust operating systems designed specifically for a...

A structured approach to the use of near-surface geophysics in long-term monitoring

The need to understand and manage earth systems means that information on the temporal and spatial behavior of these systems is needed. The typical approach used in obtaining this information is through long-term monitoring efforts. However, many of these efforts are less than successful. There are several reasons for this:

Conceptual Models of Flow through a Heterogeneous, Layered Vadose Zone under a Percolation Pond

Understanding how water and solutes move through the vadose zone is necessary to make effective remedial action decisions where contaminants were spilled or leaked at the ground surface or were buried in shallow land-disposal sites. In layered, heterogeneous systems, high contrasts in hydraulic conductivity can lead to formation of perched water zones, and enhanced lateral spread of contamination. Two conceptual models are considered solute for migration through the vadose zone. In the diffuse flow conceptual model, perched water zones accumulate until the head over the perching layer becomes sufficient to drive the infiltration through the perching layer. In the preferential flow conceptual model, perched water moves laterally until a path around the perching layer is encountered. Preferential flow paths can enhance contaminant migration because greater moisture saturation leads to higher advective velocities, and the preferential flow paths bypass low permeability layers with higher sorption capacity. Monitoring wells and instrumented boreholes were installed around a newly constructed industrial-waste percolation pond and an ephemeral river that lie over a 150-m-thick layered vadose zone. Background data gathered before discharge to the pond began show the presence of at least one, and possibly two, deep perched zones. The shallower zone, at approximately 45-m below land surface (bls), extends 800-m south of the river to the vicinity of the pond. There is a deeper zone at 90-m bls, southeast of the pond, in the direction away from the river. The river last contained water in May 2000, two years before data collection began in the summer of 2002. Two significant implications of this are (1) perched water persists for several years in the absence of surface recharge, and (2) lateral migration of perched water extends on the order of a kilometer from the river. Hydrological data collected and analyzed since discharge to the pond began in October 2002 indicate a high degree of spatial variability within the shallow subsurface, resulting in directional flow in a southern direction from discharge to the south cell and a northern direction from discharge to the north cell. Water arrival was observed at deeper locations before shallower ones, and lateral transport was observed not only at basalt/interbed interfaces but also within thick basalt layers. Recharge was observed as deep as 87-m bls and as far away as the Big Lost River 860-m to the north. New perched zones formed at the first alluvium/basalt interface on the southern end of the pond after discharge began to the south cell and at deeper lithologic interfaces where monitoring wells were completed on the northern, southern, and western perimeter of the pond. Preferential flow was found to be the most prevalent type of flow at the Vadose Zone Research Park, in contrast to the current INEEL conceptual model of vadose zone transport that adopts the diffuse flow model for contaminant transport predictions.

INSIGHTS INTO HYDRODYNAMIC AND GEOCHEMICAL PROCESSES IN A VALLEY-FILL ARD WASTE-ROCK REPOSITORY FROM AN AUTONOMOUS MULTI-SENSOR MONITORING SYSTEM

Acid mine site remediation is a significant problem, both in the U.S and globally. Due to the volume of acid producing rock the only practical solution is minimizing acid production by reducing or eliminating water flow through the rock. Typically, this is achieved through emplacement of a cap over the waste rock. The Ruby Gulch repository at the Gilt Edge Mine NPL Site is such a capped waste rock repository. Eliminating discharge from valley-fill capped waste-rock repositories is difficult and multiple factors can cause continuing oxidation and ARD discharge. Consequently, early in the cap-cover design EPA and the Bureau of Reclamation design-build team recognized the need for a long-term monitoring system which would provide actionable information on the repository performance and behavior. Specifically, the following objectives were defined for a monitoring system: 1) provide information on the integrity and performance of the newly constructed surface cover and diversion system; 2) continuously assess the wastes hydrological and geochemical behavior, such that rational decisions can be made for the operation of this cover and liner system; 3) provide easy and timely information access on system performance to a variety of stakeholders; and 4) generate information and insights which can be used to enhance future cover and monitoring discussions between EPA, the Bureau of Reclamation and DOE Idaho National Laboratory. A longterm monitoring system was designed and integrated into the multi-layered geomembanerock-soil cap-cover over the 65-acre, 450’-high, sulfide waste-rock dump to provide information to meet these objectives. The system consists of tensiometers, lysimeters and thermocouples in four wells, a 523-electrode resistivity system installed below the cap and in the wells, a weather station, and a precision outflow-meter at the toe-discharge of the repository. Continuous data from this system as well as auxiliary manually collected samples are parsed into a web accessible central server. Automated and on demand data processing allows for 2-D, 3-D and 4-D resistivity tomography and user controllable data mining. The philosophy underlying this system is that it should provide both for effective automated and autonomous data collection and for a cost effective way for multiple stakeholders to use this data. ______________________ 1 Paper presented at the 7 th International Conference on Acid Rock Drainage (ICARD), March 26-30, 2006, St. Louis MO. R.I. Barnhisel (ed.) Published by the American Society of Mining and Reclamation (ASMR), 3134 Montavesta Road, Lexington, KY 40502 2 Ken Wangerud is a Remedial Project Manager in the Superfund Remedial Program at the Environmental Protection Agency, Region 8, Denver, CO 80202. Roelof Versteeg is a Senior Advisory Scientist at the Idaho National Laboratory (INL), Idaho Falls, ID 83415. Gail Heath is a Principal Scientist at the INL, Idaho Falls, Idaho 83415. Rich Markiewicz is a scientist at the Bureau of Reclamation, Denver, CO. Alex Richardson is a scientist at the INL, Idaho Falls, Idaho, 83415. 7 th International Conference on Acid Rock Drainage, 2006 pp 2262-2281 DOI: 10.21000/JASMR06022262

MANAGING A CAPPED ACID ROCK DRAINAGE (ARD) REPOSITORY USING SEMI-AUTONOMOUS MONITORING AND MODELING 1

Effective ARD repository management requires ongoing assessment of remedial integrity and operational performance in such a manner that short and long term risks and cost are balanced and optimized. Such management requires actionable information on the behavior of the repository. This information will typically be derived from diverse data (physical, chemical and hydrological), forward and inverse hydrological, geochemical and geophysical models and cost/benefit models. With the increase in volumes of data and complexity of analysis, end users face increasing challenges in obtaining information in a timely and cost effective manner. A web accessible workflow environment for performance monitoring, designed at the Idaho National Laboratory (INL), was implemented for a capped ARD repository (the Ruby Gulch Repository) and is part of the Gilt Edge Superfund site in South Dakota. This repository is instrumented with a geophysical, hydrological and environmental sensor network. Data from this network are transmitted automatically every two hours to a server. At the server, the data are automatically parsed in a relational database and analyzed using automatically executing scripts. The resulting information is both transmitted through automated reports and accessible by users through a web application. The combination of near real time reporting and analysis and integration with analysis tools provides for actionable information on short and long term repository behavior. The structure of a web accessible workflow system for performance monitoring is well suited for both managing data, creating information and providing access to information for diverse users.

GEOPHYSICAL INVESTIGATIONS OF THE ARCHAEOLOGICAL RESOURCES AT THE POWELL STAGE STATION

Within the boundaries of the Idaho National Laboratory, an ongoing archaeological investigation of a late 19th century stage station was expanded with the use of Electro-Magnetic and Magnetic geophysical surveying. The station known as the Powell Stage Station was a primary transportation hub on the Snake River Plain, bridging the gap between railroad supply depots in Blackfoot, Idaho and booming mining camps throughout Central Idaho. Initial investigations have shown a strong magnetic signature from a buried road and previously unknown features that were not detected by visual surface surveys. Data gained from this project aids in federally directed cultural resource and land management and use requirements and has contributed additional information for archeological interpretation and cultural resource preservation.

Design and installation of a remotely controllable autonomous resistivity monitoring system at the Gilt Edge Mine superfund site, South Dakota

Acid mine site remediation is a significant problem in the U.S and globally. Due to the volume of acid producing rock involved, the only practical solution is minimizing acid production by reducing or eliminating water flow through the rock materials. One method to achieve this is utilizing a capping system. Detailed monitoring information on cap and rock behavior allows for rapid and cost-effective intervention in case of cap failure. A remotely controllable autonomous resistivity monitoring system was integrated in the repository below the geo-membrane cap at the Gilt Edge Mine Superfund site. The structure of this system allows users to have access to raw and processed data in real time. Introduction – Gilt Edge Mine The Gilt Edge mine site is located southeast of the town of Lead in the Northern Black Hills, Lawrence County, South Dakota. Mining operations for gold, copper and tungsten were conducted intermittently by several owners and operators since 1876. Cyanide leaching, mercury amalgamation and zinc precipitation were used to recover gold. About a century ago a series of small mines began dumping metal laden mill tailings into Strawberry and Bear Butte Creeks. In 1986 Brohm Mining Company got a permit to conduct large-scale open pit mining. Under the permit, BMC developed three open pits, a large cyanide heap-leach pad, and a 12 million cubic yard, valley fill, waste rock dump as well as other operations. BMC also did cleanup activities to address some historic tailings off site. Early permit applications had not mentioned acid generating materials, but sulfidic heavy metal laden rock materials were abundant. Mining ceased in 1998. During 1998-1999 BMC had serious financial difficulties and told the State that it could not continue site control. The South Dakota Department of Environment and Natural Resources (DENR) maintained necessary water treatment operations at the site, using the State’s Regulated Substance Response Fund until August 2000, when operations were turned over to EPA. In February 2000 the governor of South Dakota requested that EPA region 8 propose the site for the Superfund National Priorities List (NPL) and provide emergency response as well as long-term remedial cleanup. The site was proposed in May 2000 and was listed in December 2000. More detail about the site can be found at the EPA Superfund website at http://www.epa.gov/region8/superfund/giltedge

Automated Multisensor Monitoring of Environmental Sites: Results From the Ruby Gulch Waste Rock Repository

The last ten years have seen a fundamental shift in geoscience investigations from characterization to monitoring. This shift is present both in environmental applications and in the oil industry. In the environmental sector this change was driven by changes in industrial practices, successful efforts in addressing the most egregrous sites and changes to treatment options which include e.g. in situ engineered treatment and natural attenuation and reactive barriers. In the oil industry, this change is driven by instrumented or smart oil fields. While the goals, costs of and approaches to characterization efforts are generally well defined, the same does not yet apply to monitoring efforts (especially in the environmental sector) even though the need for effective, automated monitoring is well recognized (NAS 2005).

Using geophysics to understand arsenic occurrence in Bangladesh groundwater

The naturally occurring presence of arsenic in ground water is a growing concern in both developed and third world countries. This problem is particularly acute in West Bengal, India, and Bangladesh where most of the population relies on millions of tubewells that tap into the arsenic-enriched groundwater of the Ganges-Brahmaputra delta and where at least 25 million people drink tubewell water containing 50 microg/L resulting in a host of arsenicrelated diseases.