Characterization of a Nitrate and Technetium Plume with Environmental Geophysics
Dale Rucker, hydroGEOPHYSICS, Inc., Tucson, AZ

Investigating Coal Tar NAPL in Primary and Secondary Fractures in Bedrock
Andrew Coleman, Electric Power Research Institute, Palo Alto, CA

Estimating UXO Spatial Density Using a Composite Index Technique
Christopher Abate, AMEC Earth & Environmental, Inc., Westford, MA

Concentrations of 170 Analytes in Rural New York State Surface Soils
Emily J. Shusas, New York State Dept of Health, Troy, NY

Vertical Delineation of BTEX Using Soil, Soil Gas, and Tree Core Sampling
Stephanie Fiorenza, Atlantic Richfield Company, Houston, TX

Characterization of a Nitrate and Technetium Plume with Environmental Geophysics

Dale Rucker, hydroGEOPHYSICS, Inc.  2302 N Forbes Blvd, Tucson, AZ 85745, Tel: 520-647-3315, Fax: 520-647-3428, Email: dale@hydrogeophysics.com
Jim Fink, hydroGEOPHYSICS, Inc.  2302 N Forbes Blvd, Tucson, AZ 85745, Tel: 520-647-3315, Fax: 520-647-3428, Email: jim@hydrogeophysics.com
Chris Baldyga, hydroGEOPHYSICS, Inc.  2302 N Forbes Blvd, Tucson, AZ 85745, Tel: 520-647-3315, Fax: 520-647-3428, Email: chris@hydrogeophysics.com
Rob McGill, hydroGEOPHYSICS, Inc.  2302 N Forbes Blvd, Tucson, AZ 85745, Tel: 520-647-3315, Fax: 520-647-3428, Email: rob@hydrogeophysics.com
Marc Levitt, hydroGEOPHYSICS, Inc.  2302 N Forbes Blvd, Tucson, AZ 85745, Tel: 520-647-3315, Fax: 520-647-3428, Email: marc@hydrogeophysics.com

Fissile material production generates an enormous quantity of liquid inorganic and radioactive waste.  During the Cold War, Hanford, a production facility located in eastern Washington, generated billions of gallons of nitrate waste laden with transuranics and other radionuclides, heavy metals, and organics.  The waste was disposed in either large sealed tanks or disposed directly to the ground in unlined trenches, cribs, reverse wells, and ditches.  With a thick vadose zone, it was originally anticipated that the contaminants disposed directly to the ground would not likely reach the water table in any measurable time period.  To demonstrate waste migration beneath a former disposal site, a geophysical study was conducted on the Hanford complex at a site that contained 22 trenches and 6 cribs.  The site, called the BC Cribs and Trenches Site, received approximately 30 million gallons of sodium nitrate waste, with upwards of 400 Ci of Tc-99 during the period of 1956-1958.  The geophysical study mainly included electrical resistivity to map the distribution of electrical properties to a depth of 60 meters.  The results of the survey showed that most of the waste is tied up in the vadose zone.  However, one area near the cribs may have had a breakthrough and nitrate waste could be reaching the water table located 120 meters below ground surface.  A correlative analysis was used to convert electrical properties to nitrate concentrations, with a calculated mass balance that agreed well with the disposed mass.  Although not directly imaged with electrical resistivity method, a strong correlative relation also exists between the electrical properties and the Tc-99 concentration, which has similar transport properties as the nitrate.

Investigating Coal Tar NAPL in Primary and Secondary Fractures in Bedrock

Andrew Jay Coleman, Ph.D., P.G., Senior Project Manager, Manufactured Gas Plant Site Management, Electric Power Research Institute, 3420 Hillview Avenue, Palo Alto, CA 94303-0813, Tel: 650-855-2249, Fax: 650-855-1069, Email: acoleman@epri.com

The investigation of coal tar in bedrock at manufactured gas plant (MGP) sites can sometimes prove to be a daunting, costly, and a physically difficult task. Investigations led by blindly installing wells in the supposed upgradient and downgradient locations at a site may be case limiting to gathering an optimal set of data. Approaching a site investigation with the intention of collecting bedrock specific information on fractured networks lays a foundation for the better placement of secondary or tertiary well sets. A fracture-specific investigation approach to a well installation project may improve future site conceptual models. Using an assortment of down-hole tools helps provide qualitative data sets and also can improve the interpretation of groundwater flow in fractured networks. The sorptive capacity of certain rocks varies considerably and influences the flux of coal tar movement in fracture networks. Investigating both the matrix and secondary porosity of bedrock during continuous coring operations provides insight into the storage capacity of a fractured network.  Contaminants can either sorb to rock or diffuse through fractures depending on the rock type. Differentiating the ratio between sorption and diffusion partially becomes a function of the ability to isolate discrete fracture networks during down-hole investigations. New promising down-hole bedrock investigation techniques can provide a site investigator with the opportunity to install less intrusive bore holes at a site and yield the same amount of information from many holes drilled.  More characterization from one or two wells rather than from many is also more cost effective and reduces the risk of interconnecting fractures at a site which can potentially cause widespread NAPL dispersion in bedrock aquifer fracture networks.

Estimating UXO Spatial Density Using a Composite Index Technique

Ken Hnottavange-Telleen, Christopher Abate, Kim Groff, Herbert Colby, and Joe Robb, AMEC Earth & Environmental, 239 Littleton Road, Suite 1B, Westford, MA 01886, Tel: 978-692-9090, Fax: 978-692-6633
William Gallagher, U.S. Army, Impact Area Groundwater Study Program Office,   PB 565/567 West Outer Road, Camp Edwards, MA 02542
Scott Greene, U.S. Army Corps of Engineers, 696 Virginia Rd., Concord, MA  01742-2751

Mapping spatial density of Unexploded Ordnance (UXO) at a military training range using conventional methods is costly and dangerous. The presented methodology predicts UXO density by overlaying multiple independent datasets to compute a composite index. At the 21,000-acre Massachusetts Military Reservation (MMR), a 1,600-acre area was divided into one-acre grid cells. Three metrics representing historical evidence, process knowledge, and present signature were used to build a relative spatial-density ranking for each cell.

Historical evidence includes records that directly map site conditions or activities related to UXO deposition. These data may include mapped cratered or burned areas or records of training activities, if geographically specific. For MMR, historic air photos revealing temporary vegetation clearance caused by ordnance impact were used to map a time-weighted clearance value for each grid cell. Process knowledge leverages the understanding of how the spatial UXO distribution was created. At MMR, because artillery shells were fired at specific targets, we were able to construct a curve of declining UXO density with distance from a known target, based on limited site-specific data. This relation was used to compute a target proximity value for each grid cell. Present signature includes data that directly reflect UXO presence in soil. At MMR, aeromagnetic data are available, and median signal intensity correlates with known UXO density. During analysis it was discovered that using the median-intensity statistic reduces the effect of the large metallic target objects. Data sets in this category that may exist at other sites include spectral/remote sensing, and mapped geochemical and geobotanical data.

By compositing the three metrics, a relative index value was created for each grid cell that was then scaled by comparison to areas of known UXO density. A field program designed to validate this methodology through intrusive investigation is planned for summer 2006.

Concentrations of 170 Analytes in Rural New York State Surface Soils

Stephen J. Shost, M.P.H., New York State Department of Health, Bureau of Toxic Substance Assessment, Flanigan Square, 547 River Street, Room 330, Troy, NY, 12180-2216, Tel: 518-402-7833, Fax: 518-402-7819, Email: sjs12@health.state.ny.us
Emily J. Shusas, M.A., New York State Department of Health, Bureau of Toxic Substance Assessment, Flanigan Square, 547 River Street, Room 330, Troy, NY, 12180-2216, Tel: 518-402-7813, Fax: 518-402-7819, Email: ejs09@health.state.ny.us
Dean B. Briggs, M.S., New York State Department of Health, Bureau of Toxic Substance Assessment, Flanigan Square, 547 River Street, Room 330, Troy, NY, 12180-2216, Tel: 518-402-7829, Fax: 518-402-7819, Email: dbb01@health.state.ny.us

Few published data describe typical concentrations of chemicals in the shallow surface soils of rural New York State.  We conducted a statewide survey that determined concentrations of 170 analytes in 269 discrete surface soil samples collected from randomly selected rural parcels.  Rural properties (n=125) were selected for sampling using a digitized grid map and a random number generator.  Target analytes included volatile and semi-volatile organic compounds (VOCs/SVOCs), organochlorine pesticides (OCPs), Aroclor mixtures of polychlorinated biphenyls (Aroclors), metals, amenable cyanide and total cyanide.  Field staff collected at least two types of surface soil samples at each property: a "source-distant" sample and a "remote" sample.  Source-distant samples (0-5 centimeters depth) were obtained from areas that were reasonable points of human contact with soil but at least 5 meters distant from potential sources of the target analytes (e.g., trash, roadways, driveways or structures).  Remote samples (0-15 centimeters depth) were collected from areas that were not foci of regular human activity.  At a subset of properties, staff also collected a "near source" soil sample (0-5 centimeters depth) near a roadway or driveway (n=28).  After completion of sampling, field documentation and aerial photographs were reviewed to identify a subset of 96 remote samples that were collected from habitat, defined as areas potentially providing food and shelter for wildlife, that appeared only marginally influenced by human activity.  Several metals were frequently detected in all sample types, and several SVOCs were frequently detected in near source samples.  Most other analytes were rarely, if ever, detected.  For example, Aroclors and OCPs were rarely detected, and neither total cyanide nor amenable cyanide was detected in any sample.  These data contribute substantially to our understanding of current analyte levels in rural soils, especially with regard to differences among the rural environments surveyed.

Vertical Delineation of BTEX Using Soil, Soil Gas, and Tree Core Sampling

Stephanie Fiorenza, Atlantic Richfield Company, 501 Westlake Park Blvd., Houston, TX 77079, Tel: 281-366-7484, Fax: 281-366-7094, Email:  Stephanie.Fiorenza@bp.com
Frank Thomas, KMA, 25330 FM 2004, Angleton, TX 77515, Tel: 409-599-3384, Fax:  409-599-3384, Email: phytofarms@wt.net
Joshua Fell, URS Corporation, 1600 Perimeter Park Drive, Suite 400, Morrisville, NC 27560, Tel: 919-461-1383, Fax: 919- 461-1415, Email: Joshua_Fell@URSCorp.com
Jay W. Hodny, W. L. Gore & Associates, Inc., 100 Chesapeake Boulevard, Elkton, MD 21921, Tel: 410-506-4774 Fax: 410-506-4780, Email: jhodny@wlgore.com

At a gas station site in Raleigh, North Carolina, free product is encountered 20 ft bgs at the station grade and 10 ft bgs down slope from the station, adjacent to a creek.  Mature trees are present on the slope, and, at the station grade, trees were planted to aid in hydraulic containment and phytoremediation.  A prior investigation at the site detected low levels of benzene in two tree trunk cores collected down slope.  To confirm these results and investigate the concentration gradient from the free phase product up to the rhizosphere, soil gas samples were collected using GORE^TM Modules, passive, sorbent-based samplers, placed at three different depths in co-located boreholes.  Discrete soil samples were collected at corresponding depths under the mature trees, beneath the phytoremediation stand, and in a treeless area down slope.  Modules were also inserted into tree core holes to determine BTEX presence within the tree systems.

Soil gas and tree cores were analyzed for volatile and semivolatile organic chemicals and soil samples were analyzed for VOCs only.  The soil gas results showed a two to three order -of -magnitude decrease in BTEX mass within five feet of the free phase gasoline interface;  BTEX was trace to undetectable in shallow (2.5 bgs) soil gas and core samples.  BTEX was observed in GORE^TM Modules inserted into tree core holes.  In this field investigation, the GORE^TM Modules were effective in delineating the vertical extent of BTEX in soil gas; this ability may prove useful in vapor intrusion investigations. The module placement inside the tree is in effect an in-tree extraction, and reflects the uptake of these compounds by the tree.  When compared to repetitive tree trunk coring with an increment borer, sampling with GORE^TM Modules is minimally invasive, sensitive to low concentrations, and may allow for repetitive sampling. 

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