bluuebunny/crossref_metadata_2025 huggingface dataset:
Volume Determination and Recoverability of Free Hydrocarbon
Authors: Testa Stephen M. , Paczkowski Michael T.
Published: February 2007

Free‐phase hydrocarbon product occurs as perched zones on the capillary fringe beneath numerous petroleum‐handling facilities. Under such site conditions, too much emphasis is placed on the time‐frame required for remediation by federal, state, and local regulators, notably in respect to monitoring the efficiency and effectiveness of the respective remediation program. The time required for remediation within the scope of present‐day technology is a calculated or educated guess at best. Typically, remediation duration is determined by a number of estimates. These estimates have innate compounding errors. Areas of estimation include physical measurement accuracy; “true” vs. apparent thickness; validity of bail‐down testing; extrapolation of free hydrocarbon product thicknesses between monitoring points; contouring of thickness maps, extrapolation of geologic information, planimetering, and estimation of porosity; specific yield and retention; all of which are key factors used in ultimately determining the volume of free hydrocarbon product in place.

Once an initial estimated volume is determined, pilot testing of a recovery system should commence to determine recovery rates.

Factors that will affect recovery rates include the areal distribution and geometry of the hydrocarbon pool, type, and number of recovery system(s) selected, and the performance or efficiency of these systems with time. Effectiveness of the recovery program is thus best estimated based on barrels recovered to date divided by the total volume of barrels that are considered recoverable.

Remediation time frame at petroleum hydrocarbon recovery sites can be estimated. However, regulators at all levels need to be aware of the large number of compounding errors associated with these calculations. Estimations should be used with extreme caution, because they are usually overestimations. Once a realistic time frame for remediation is mutually agreed upon, it should be clearly understood that it is flexible. It is recommended that a range be initially determined and that as a project progresses and new data are introduced, the remediation time frame be adjusted accordingly.
Flush‐Joint Threads Find a Home
Authors: Foster Shawn
Published: February 2007

With the rapid growth of PVC in the well casing and screen market, many different applications and methods of use have surfaced. One major method of fastening or joining thermoplastic well casing is the flush‐joint thread. Widespread use of flush‐joint threads on Schedule 40 and Schedule 80 pipe has caused concern about the physical strength and hydrostatic integrity of these threads. These concerns are magnified when one discovers the multitude of different manufacturers, each with his own thread design. There has, however, been a solution: Committee F17 of ASTM has passed a change in the Standard F480, which is now: ASTM F480–88A Standard Specification for Thermoplastic Well Casing and Couplings Made In Standard Dimension Ratios (SDR), Schedule 40 and Schedule 80. This change partially consists of incorporating specifications for flush‐joint threads in Schedule 40 and Schedule 80 casing, in sizes ± inch to 16 inch in Schedule 80 and 2 inch to 16 inch in Schedule 40. This long overdue standard now ensures field thread compatibility with all pipe specified with this standard. It also requires manufacturers to cut a functional and reliable thread.

Extensive testing has been done to determine the physical properties of the specified thread. The three tests that help the purchaser determine the working parameters of this flush‐joint thread include:

1. Tensile test of the threaded joint

2. Internal hydrostatic pressure test

3. External hydrostatic pressure test.

Using ASTM guidelines test methods were developed for testing this thread. Results show that the new thread specification in F480 is a valid and functional design.
Equipment Decontamination Procedures for Ground Water and Vadose Zone Monitoring Programs: Status and Prospects
Authors: Mickam James T. , Bellandi Robert , Tifft Edwin C.
Published: February 2007

A 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.
Using Soil and Meteorologic Data Bases in Unsaturated Zone Modeling of Pesticides
Authors: Carsel Robert F. , Jones Russell L.
Published: February 2007

Various types of models are being used to evaluate pesticide transport and transformation in the unsaturated zone. Model predictions can be used, for example, to develop alternative agricultural management strategies for pesticide use. However, intensive data requirements for transient models sometimes deter their use. Site‐specific measurements are preferred, but existing data bases can be used as a source of required model parameters, especially weather and soil characteristics. These existing data bases make possible the use of models to predict leaching potential in a wide variety of environments.
Ground Water Monitoring at Wellhead Protection Areas
Authors: Meyer Philip D.
Published: February 2007

Wellhead protection programs implemented to this date have not, in general, included a comprehensive ground water monitoring strategy. This is due both to the relatively recent introduction of the wellhead protection concept into the ground water field and also to the complexity of the monitoring problem. A well‐planned monitoring program, however, can contribute significantly to the success of a wellhead protection program. The elements of wellhead protection, important from a monitoring perspective, are the management objectives, the types of potential contaminant sources, and the locations of those sources with respect to the wellhead protection area boundary. General monitoring strategies applicable to wellhead protection are derived from the relationships between these elements.
A National Evaluation of the Leaching Potential of Aldicarb Part 2. An Evaluation of Ground Water Monitoring Data
Authors: Lorber Matthew N. , Cohen Stuart Z. , DeBuchananne George D.
Published: February 2007

Aldicarb was first found in ground water in Suffolk County, New York, in the late 1970s associated with its use on potatoes. Since then, there has been a substantial amount of monitoring associated with aldicarb use on potatoes nationally and on citrus in Florida. A recent monitoring study by the registrant of aldicarb supplemented limited monitoring data on other critical aldicarb uses including cotton and peanuts. This paper reports on monitoring programs and studies encompassing more than 50,000 ground water samples, of which approximately 32 percent are positive and 13 percent are above EPA's Health Advisory Level of 10 ppb. These monitoring results were used in an integrated assessment to identify areas of the United States where aldicarb is likely to leach to ground water (Lorber et al. 1989). Positive findings are reported for 61 counties in 19 states, and findings above 10 ppb are reported for 31 counties in 11 states. Monitoring data associated with the use of aldicarb on potatoes in the Northeast and upper Midwest (Wisconsin, Virginia, New York, Massachusetts, Rhode Island, Maine) are extensive and demonstrate the potential for aldicarb to impact ground water near potato‐use sites. In contrast, monitoring associated with potato use in the Northwest (Idaho, Oregon, Washington) and a three‐county potato‐growing area in Florida have shown negative results. Sampling near cotton use in the South and Southwest (Georgia, Alabama, Tennessee, Arkansa, Louisiana, Texas, Arizona) showed negative findings, while a small number of positives were found in North Carolina and South Carolina. Limited monitoring associated with peanuts showed negative results in the South (North Carolina, South Carolina, Georgia), although sampling beneath a field research site in Georgia showed trace positives. Sampling from monitoring wells established in the shallow water table aquifer beneath and downgradient from citrus use sites in Florida showed both a high frequency and high concentrations of aldicarb, with one finding above 1000 ppb and numerous findings greater than 100 ppb. However, in three separate efforts encompassing more than 1200 samples from roughly the same number of domestic drinking water wells located near citrus fields with histories of aldicarb usage, only 2 percent contained residues of aldicarb. No positives were found in 800 samples from roughly the same number of deep public drinking water wells in counties with high citrus acreage and aldicarb usage. This paper also reports on monitoring associated with lily bulb use in northern California, fernery use in Florida, sugar beet use in Montana, and smaller exploratory efforts in several other states.
Accounting for Temporal Variations in Large‐Scale Retrospective Studies of Agricultural Chemicals in Ground Water
Authors: Liddle Susan K. , Whitmore Roy W. , Mason Robert E. , Alexander W. Joseph , Holden Larry R.
Published: February 2007

Ground water studies that require long data collection periods may be affected by temporal changes in ground water chemistry. Seasonal fluctuations in ground water chemistry are particularly apparent in shallow aquifers. Of specific interest is the inclusion of temporal variability in the design of statistical surveys of agricultural chemicals in well water. Statistical treatment of temporal variability involves selecting a probability sample from temporal units. The selection strategy may include repeating the same spatial units in each temporal stratum or choosing an independent sample of spatial units for each temporal stratum. The appropriate strategy depends on the specific study objectives. Failure to account for temporal variability may compromise the validity of study conclusions. An example of a large‐scale retrospective survey designed to estimate temporal averages of water quality across all wells is presented.
Pesticide Contamination of Ground Water Artificially Recharged by Farmland Runoff
Authors: Exner Mary E.
Published: February 2007

Atrazine, cyanazine, alachlor, and metolachlor in the surface water of a recharge structure, which impounds runoff from row‐cropped farmland in Nebraska, are transported with seepage to the shallow ground water flow system and to the locally confined regional aquifer. All wells in the shallow flow system and all those in the regional flow system impacted by seepage from the structure had detectable concentrations of at least one of the four pesticides.

The detectable concentrations of cyanzine, alachlor, and metolachlor in the two flow systems ranged from 0.1 to 0.9 ppb. These concentrations were an order of magnitude lower than those in the surface water. Concentrations in the regional aquifer clustered at the lower end of this concentration range. These three pesticides were not detected in the baseline study of the regional aquifer.

Unlike alachlor, cyanzine, and metolachlor, atrazine was always present in the wells impacted by seepage from the recharge structure. In the shallow flow system, concentrations ranged from 0.3 to 8.8 ppb and from 0.1 to 2.5 ppb in the regional aquifer. The average of the detectable atrazine concentrations in the baseline study was 0.04 ± 0.05 ppb.
A Supplementary Method for Assessing the Reliability of Fluids Sampled from Deep Aquifers
Authors: Nativ Ronit
Published: February 2007

In deep aquifers, temperatures of formation fluids recovered during drill‐stem tests were usually higher than regular bottom‐hole temperatures recorded at the same borehole and interval. Wherever the opposite was observed, the sampled formation fluids were diluted with mud filtrate or cushion water. Temperature measurements are a useful criterion for differentiating between representative and contaminated formation‐fluid samples.
Development of a Standard, Pure‐Compound Base Gasoline Mixture for Use as a Reference in Field and Laboratory Experiments
Authors: Kreamer David K. , Stetzenbach Klaus J.
Published: February 2007

In recent years, leaking underground petroleum storage tanks have become a major environmental concern. Federal, state, and local agencies are making efforts to assess, control, and remediate petroleum product leaks. Because petroleum products are mixtures of many compounds and the composition frequently changes, there exists a need for a standard reference mixture that can be used as a basis for comparison in the study of fluid transport properties in porous media and to evaluate leak detection devices. The proposed standard presented here retains the most important liquid and vapor properties (such as vapor density, air diffusion coefficient, and basic chemical constituency) of gasoline mixtures. It also reduces the complexity of the mixture to make it an acceptable standard for routine use in laboratory and field experiments.
Influence of Casing Materials on Trace‐Level Chemicals in Well Water
Authors: Parker Louise V. , Hewitt Alan D. , Jenkins Thomas F.
Published: February 2007

Four well casing materials — polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and stainless steel 304 (SS 304) and 316 (SS 316) — were examined to determine their suitability for monitoring inorganic and organic constituents in well water.

The inorganic study used a factorial design to test the effect of concentration of mixed metals (arsenic [As], chromium [Cr], lead [Pb], and cadmium [Cd]), pH, and organic carbon. Sample times were 0.5, 4, 8, 24, and 72 hours. Except for slow loss of Pb, PTFE well casings had no significant effect on the concentration of metals in solution. For the other casings, changes in analyte concentration often exceeded 10 percent in eight hours or less and, thus, could bias analyses of samples taken from wells constructed with these materials. Specifically, PVC casings sorbed Pb and leached Cd; SS 316 casings sorbed As and Pb and leached Cd; and SS 304 casings sorbed As, Cr, and Pb and leached Cd. Both stainless steel casing materials showed markedly poorer performance than the PVC casings.

The well casings were also tested for sorption/desorption of 10 organic substances from the following classes: chlorinated alkehes, chlorinated aromatics, nitroaromatics and nitramines. Sample times were 0, 1, 8, 24, and 72 hours, seven days, and six weeks. There were no detectable losses of analytes in any of the sample solutions containing stainless steel well casings. Significant loss of some analytes was observed in sample solutions containing plastic casings, although losses were always more rapid with the PTFE casings than with PVC. Chlorinated organic substances were lost most rapidly. For samples containing PTFE casings, losses of some of these compounds were rapid enough (>10 percent in eight hours) to be of concern for ground water monitoring. Losses of hydrophobic organic constituents in samples containing PTFE casings were correlated with the compound's octanol/water partition coefficient.
Application of Marine Seismic Profiling to a Ground Water Contamination Study, Aberdeen Proving Ground, Maryland
Authors: Hughes W. Brian
Published: February 2007

Continuous high‐frequency marine seismic profiling was used to define the extent of geologic units in the offshore areas of J‐Field, Aberdeen Proving Ground, Maryland, during March and April of 1988. J‐Field is an area that was used by the U.S. Army for disposal of chemical warfare agents, munitions, and organic solvents from the 1950s through the 1970s. A major concern at this site is the subsurface migration of hazardous wastes into offshore areas and eventually into the Chesapeake Bay. A 150‐foot (45.7 meter) deep paleochannel containing Pleistocene age fluvial and estuarine sediments was identified from boreholes constructed onshore. The paleochannel sediments consist of three lithic units. From bottom to top these units consist of gravel and sand, massive silty and sandy clay, and interbedded sand and clay. The seismic profiles were used to identify the extent of these units and map them in offshore areas. An accurate knowledge of the distribution of the geologic units in onshore and offshore areas is important to the investigation because the coarse‐grained paleochannel sediments may provide a preferential flow path for contaminated ground water and the fine‐grained sediments may impede the movement of contaminants into deeper aquifers.
Cone Penetrometer Tests and HydroPunch® Sampling: A Screening Technique for Plume Definition
Authors: Smolley Mark , Kappmeyer Janet C.
Published: February 2007

Cone penetrometer tests and HydroPunch® sampling were used to define the extent of volatile organic compounds in ground water. The investigation indicated that the combination of these techniques is effective for obtaining ground water samples for preliminary plume definition. HydroPunch samples can be collected in unconsolidated sediments and the analytical results obtained from these samples are comparable to those obtained from adjacent monitoring wells. This sampling method is a rapid and cost‐effective screening technique for characterizing the extent of contaminant plumes in soft sediment environments. Use of this screening technique allowed monitoring wells to be located at the plume boundary, thereby reducing the number of wells installed and the overall cost of the plume definition program.
Field Sampling of Residual Aviation Gasoline in Sandy Soil
Authors: Ostendorf David W. , Leach Lowell E. , Hinlein Erich S. , Xie Yuefeng
Published: February 2007

Two complementary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured field extrusion of core barrels into pint‐size Mason jars, while the second consisted of laboratory partitioning of intact stainless steel core sleeves. The barrel extrusion procedure involved jar headspace sampling in a nitrogen‐filled glove box, which delineated the 0.7m thick residually contaminated interval for subsequent core sleeve withdrawal from adjacent boreholes. Soil samples removed from the Mason jars (in the field) and sleeve segments (in the laboratory) were subjected to methylene chloride extraction and gas chromatographic analysis to compare their aviation gasoline content. The barrel extrusion sampling method yielded a vertical profile with 0.10m resolution over an essentially continuous 5.0m interval from the ground surface to the water table. The sleeve segment alternative yielded a more resolved 0.03m vertical profile over a shorter 0.8m interval through the capillary fringe. The two methods delivered precise estimates of the vertically integrated mass of aviation gasoline at a given horizontal location, and a consistent view of the vertical profile as well. In the latter regard, a 0.2m thick lens of maximum contamination was found in the center of the capillary fringe, where moisture filled all voids smaller than the mean pore size. The maximum peak was resolved by the core sleeve data, but was partially obscured by the barrel extrusion observations, so that replicate barrels or a half‐pint Mason jar size should be considered for data supporting vertical transport analyses in the absence of sleeve partitions.
Identifying Potential Pollutant Point Sources in an Area of High Ground Water Consumption
Authors: Davis Ronnie McConnell , Flores Patricia Irene
Published: February 2007

The Commonwealth of Pennsylvania relies heavily upon its ground water resources for drinking water. The U.S. Environmental Protection Agency, Region III, is responsible for regulating the discharge of waste to the subsurface through injection wells within Pennsylvania. To facilitate identification of industrial facilities unregulated by EPA that may be contaminating ground water through industrial water and waste water discharge wells, a screening procedure was devised utilizing a Geographic Information System (GIS). This procedure involved cross‐referencing locations of industrial sites to maps of municipal sewer systems. The effectiveness of this GIS screening procedure was investigated in seven counties in southeastern Pennsylvania. Facilities identified by the procedure were inspected for possible violations of Underground Injection Control (UIC) program regulations. As a result of these inspections, many facilities were found to be illegally discharging waste into ground water. In addition, other EPA program violations were identified. The project demonstrated that the GIS screening procedure can be an effective tool to locate sources of pollution of ground water.
Statistical Modeling of Hydrogeologic Data ‐ Part I: Regression and ANOVA Models
Authors: Kufs Charles T.
Published: February 2007

Statistical modeling can be a powerful tool for analyzing complex hydrogeologic and water quality data. The objectives of this paper are to discuss the nature of statistical models; to describe two types of statistical models, regression models, and analysis of variance (ANOVA) models; and to give examples of how the models have been and could be applied to solve hydrogeologic problems.
Suggested Modifications to Ground Water Sampling Procedures Based on Observations from the Colloidal Borescope
Authors: Kearl Peter M. , Korte Nic E. , Cronk Tom A.
Published: February 2007

Observations of colloidal movement under natural conditions and during pumping were conducted at several field sites. Results indicate that several modifications to present sampling protocols may improve the representativeness and cost effectiveness of obtaining ground water samples for assessing the total mobile contaminant load. These modifications include the installation of dedicated sampling devices, limited purging of the well prior to sampling, sampling at a flow rate of 100 mL/min, and no filtering of samples. This sampling approach can result in significant cost savings while providing the best possible water samples.
A New Pumping Strategy for Petroleum Product Recovery from Contaminated Hydrogeologic Systems: Laboratory and Field Evaluations
Authors: Abdul Abdul S.
Published: February 2007

More than 200,000 gallons of automatic transmission fluid (ATF) leaked from an underground storage tank system and contaminated an area of about 64,000 ft2 of a soil and ground water system. A pumping strategy for improved drainage and recovery of free oil was developed, tested in a laboratory model aquifer, and implemented and evaluated at the field site. This pumping strategy differs from conventional approaches in two important ways: (1) The oil recovery rate is carefully controlled to maximize the pumping rate while maintaining continuity between the oil layer in the soil and the recovery well, to avoid isolation of the oil in the subsurface; and (2) The rate of ground water pumping is controlled to maintain the depressed oil/water interface at its prepumped position. This approach prevents further spread of oil into the ground water, prevents reduction in the volume of recoverable oil due to residual retention, and maintains a gradient for oil flow toward the recovery well. In a model aquifer study, nearly 100 percent of the recoverable volume of ATF was pumped from the system, and about 56,000 gallons of the ATF has been recovered from the field site.
A Diffusive Sampler for Passive Monitoring of Underground Storage Tanks
Authors: Karp Kenneth E.
Published: February 2007

Passive measurements of volatile organic compounds (VOCs) provide a method for early detection and long‐term monitoring of potential leaks from underground storage tanks (USTs) and associated fuel service lines. A diffusive sampler was constructed of a sorbent tube that fits inside a specially designed sampling chamber. VOCs in the soil enter the chamber by molecular diffusion and are collected by the sorbent. The sorbent is easily retrieved for laboratory analyses by thermally desorbing into a gas chromatograph/mass spectrometer (GC/MS), or qualitative concentrations can be determined directly in the field with specific‐indicator detectors.

The diffusive samplers were evaluated in an exposure chamber under controlled conditions. Laboratory measurements of the sorbed mass of organic vapor were found to be in close agreement with theoretical values and indicate the passive sampling approach is viable for detecting relatively low concentrations of organic vapors in the vadose zone over a one‐day sampling period, as well as providing relatively long‐term monitoring periods up to 58 days. A field test found the sampling approach successful in identifying an area where the vadose zone was contaminated by leaking petroleum USTs.
Field vs. Lab Alkalinity and pH: Effects on Ion Balance and Calcite Saturation Index
Authors: Shaver Robert B.
Published: February 2007

Ground water samples for a hydrochemical investigation were collected from 92 observation wells completed in a shallow, unconfined aquifer in southeastern North Dakota. The samples showed predominantly an increase in HCO3‐ (positive bias) and both a pH decrease (positive bias) and a pH increase (negative bias) from field to lab. Positive pH bias generally was associated with ground water characterized by dissolved‐solids concentrations less than 400 mg/L. Negative pH bias generally was associated with ground water characterized by dissolvedsolids concentrations greater than 400 mg/L.

Observed HCO3‐ bias from field to lab slightly distorted ion balance distribution. Excess anions greater than 2 percent generally corresponded to increased HCO3‐ from field to lab.

Observed HCO3‐ and pH bias significantly distorted the distribution of calcite saturation indices. Samples with dissolved‐solids concentrations less than 400 mg/L that generally showed a positive pH bias had a mean change in calcite saturation index of ‐0.214 (toward undersaturation). Samples with dissolved‐solids concentrations greater than 400 mg/L that generally showed a negative pH bias had a mean change in calcite saturation of +0.132 (toward over saturation).

Calcite saturation indices were much more sensitive to observed pH bias than to observed HCO3‐ bias. Linear regression analysis indicates % percent of the variability in calcite saturation index change from field to lab is attributed to change in pH from field to lab. Field pH should be used to compute calcite saturation index.
Atrazine in a Stream‐Aquifer System: Transport of Atrazine and Its Environmental Impact Near Ashland, Nebraska
Authors: Blum Darryl A. , Carr James D. , Davis Ralph K. , Pederson Darryll T.
Published: February 2007

Lincoln's municipal wellfield consists of 44 wells located adjacent to the Platte River near Ashland, Nebraska. The herbicide atrazine was monitored in the river and two transects of monitoring, wells. The amount of atrazine transported down the Platte River in 1989, 1990, and 1991 was shown to increase each year. Induced recharge from the Platte River results in movement of atrazine from the river into the aquifer. A 21‐day lag time was determined for the movement of atrazine from the river to a transect of monitoring wells 10 feet West of the bank. The role that colloids play on the transport of atrazine was determined to be insignificant. A small percentage of atrazine found in the river was determined to come from rain water. The infiltration of agrichemical‐contaminated river water was shown to significantly reduce the quality of raw water and finished water being produced by the adjacent aquifer.
Atrazine in a Stream‐Aquifer System: Estimation of Aquifer Properties from Atrazine Concentration Profiles
Authors: Davis Ralph K. , Pederson Darryll T. , Blum Darryl A. , Carr James D.
Published: February 2007

Lincolns municipal wellfield consists of 44 wells developed in an alluvial aquifer adjacent to the Platte River near Ashland, Nebraska Induced recharge from the river is the primary source of water for the wellfield. Wafer samples were collected on a periodic basis from the Platte River arid two transects of monitoring wells. These samples were analyzed for the herbicide atrazine, which was used as a tracer of induced recharge in this stream‐aquifer system. Atrazine concentrations in the river and aquifer were much less than 1.0 ppb during late fall and winter, but increased to as high as 18.9 ppb during spring and summer, associated with runoff from upgradient agricultural lands. There was approximately a 21‐day lag time from the first detection of increasing atrazine concentration in the river to the first detection in monitoring wells immediately adjacent to the river. This lag time was relatively constant throughout the year and from one year to the next, even with major fluctuations of river stage and wellfield production. This consistency of lag time indicated that the travel times from the river to the first set of monitoring wells immediately adjacent to the river were fairly constant.

Paths of preferential flow were identified in the aquifer at a depth of 25 to 35 feet below land surface. This aquifer zone appeared to play a significant role in movement of water from beneath the river into the wellfield.

Aquifer dispersivity was calculated using a method described by Hoehn and Santschi (1987). Macrodispersivity (AL) was shown to increase linearly over the scale of the wellfield. Calculated values of AL were within limits of other reported values for this type of aquifer material and agreed well with values reported by Hoehn and Santschi (1987); These findings will be extremely beneficial for planning and management of the municipal wellfield.
Differences Between Water‐ Level Probes
Authors: Plazak Dan
Published: February 2007

Water‐level probes, even of the same make and model, may not give the same water‐level measurement. If more than one probe is used on a site, it may be useful to measure the differences in water‐level measurements, and, if necessary, to normalize the water levels to a single reference probe.
The Resonant Sonic Drilling Method: An Innovative Technology for Environmental Restoration Programs
Authors: Barrow Jeffrey C.
Published: February 2007

The resonant sonic drilling method offers unique capabilities to the environmental restoration market. By using a drill head that imparts high‐frequency, high‐force vibrations into a steel drill pipe, continuous, relatively undisturbed cores can be taken through virtually any formation. The resonant sonic method requires no mud, air, water, or other circulating medium for penetration: drills very fast; easily drills at any angle through formations such as rock, clay, sand, boulders, permafrost, or glacial till; and yields no cuttings in the drilling process. Case histories of projects using the method demonstrate excellent results but also indicate several problem areas with the method in its present state. Expanding research efforts to further develop the resonant sonic drilling method should help solve current drawbacks, and could produce a drilling technology for environmental work that significantly changes the way monitoring wells are drilled and constructed.
Leaching Potential of Turf Care Pesticides: A Case Study of Long Island Golf Courses
Authors: Primi Patricia , Surgan Michael H. , Urban Timothy
Published: February 2007

Pesticides used to maintain golf course turf can threaten ground water. This concern is particularly important in most of New York's Long Island, where generally sandy soils overlie a sole source aquifer. This study uses two methods to evaluate the potential for pesticides that are commonly used on Long Island's golf courses to leach to ground water.

Adapting the Pesticide Root Zone Model (PRZM). Release 1. for dense turf and applying site‐specific soil data, certain pesticides, including metalaxyl and trichlorfon, are identified as potential problem leachers. PRZM simulations also identify the Long Island soils, including the sandy Plymouth and Carver soils, which arc most vulnerable to leaching.

When adequate input data for PRZM is unavailable, the ground water ubiquity score (GUS) method may be useful. GUS teachability classifications of pesticides commonly applied on Long Island golf courses, and of pesticides actually detected in ground water samples taken on Long Island, agree with PRZM predictions and the field data. The GUS method is applied to the evaluation of the leaching potential of pesticide degradation products (DCPA, maneb, and mancozeb metabolites), and the degradation products are shown to be a greater threat to ground water than their parent compounds.

These methods are potentially useful in designing ground water monitoring programs and for guiding the pesticide use and selection decisions of golf course managers.
Ground Water Monitoring Statistics Update: Part II: Nonparametric Prediction Limits
Authors: Davis Charles B. , McNichols Roger J.
Published: February 2007

Nonparametric prediction limits can be useful statistical tools for ground water monitoring at facilities regulated under RCRA Subtitle C. Subtitle D. and similar regulations. New, exact tables arc presented for both “1 of m” plans (m chances to gel one observation inbounds at each of r monitoring wells to avoid a statistically significant increase) and “California” plans (first or all of the next m‐1 observations inbounds at each well). The tables provide per‐constituent significance levels (false positive rates) as a function of the background sample size n. m. r, the prediction limit (the largest or the next to largest, background observation), and the confirmatory resampling plan selected.

When used in a monitoring program, future observations from several wells are compared with a prediction limit obtained from a common background sample. The table significance levels therefore depend critically on having IID (independent and identically distributed) observations. In particular, the false positive rate computations are not valid, and the procedures should not be used, with constituents whose measurements exhibit inherent spatial or systematic temporal variability.

Recent U.S. EPA guidance explicitly encourages controlling facility‐wide false positive rates over both constituents and wells. Nonparametric prediction limits, particularly with California resampling plans, will have greater difficulty in meeting the new. lower per‐constituent false positive rate goals than previous ones, especially if many constituents are involved. Nonetheless, nonparametric prediction limits remain superior to other commonly used procedures for dealing with data with high proportions of nondctects.
A Risk‐Based Approach for Managing Hazardous Waste
Authors: Chiang C.Y. , Petkovsky P.D. , McAllister P.M.
Published: February 2007

In 1992, the U.S. Environmental Protection Agency (EPA) proposed risk‐based management of hazardous waste. A major component of the proposed rule is the determination of non‐site‐ specific screening concentration levels from waste leachate. Ground water at a downgradient exposure point must not exceed those screening levels, or more stringent requirements would apply.

The screening concentration level is determined with verified models and equations that simulate the transport and attenuation of chemicals as they travel from the source area to the exposure point. A consortium of screening levels is determined in this paper by considering varying physical, chemical, and biological conditions. In addition, a method is developed for multi component leaching from contaminated soils in a landfill to determine the time‐dependent behavior of a finite source. Finally, this paper discusses infiltration rate through the clay liner.
A Field Study of Enhanced Recovery of DNAPL Pooled Below the Water Table
Authors: Michalski Andrew , Metlitz Michael N. , Whitman Ira L.
Published: February 2007

A large subsurface pool of waste solvent product, consisting primarily of 1,1,1‐tichloroethanc and carbon tetrachloride, was encountered during investigations at an industrial site in northern New Jersey. In the 1950s the product was discharged through a settling chamber directly below the shallow water table. Eventually the product accumulated within elongated depressions of erosional surface of varved clays at depths 10 to 15 feet below grade. The host sediment, line to medium sand, was overlain by line sand and silt. The delineated area of pooled DNAPLs covered 2750 feet2, and the maximum pool thickness exceeded 3 feel.

The primary recovery involved pumping product from nine wells. Each recovery well was equipped with a sump extending into the clay, which enabled the system to keep the product pumping level below the bottom of the pool. A total of 3495 gallons of solvent product was recovered over two years. Nearly half of this volume was produced by two wells placed at the lowest points of the pools. Postpumping sampling of the former pools indicated that 43 to 94 percent of the pooled solvent mass was removed during the primary recovery. Average initial product salutation within the pool was estimated at 53.2 percent of the total porosity measured at 31 percent. Average residual saturation after the primary product recovery was 3.7 percent of the total pore volume.

To test the feasibility of residual product recovery, an experimental secondary recovery was undertaken. Using sheet piling, a 506 feet2 lest cell was constructed inside the former DNAPL pool. The cell featured a central recovery well, six peripheral wells, and monitoring probes. I he selected sequence of secondary operations included partial dewatering. hot water injection, final dewatering, and thermally enhanced vapor extraction (TVE). During six weeks of the secondary recovery operations. 87.9 gallons of product were removed, of which 72 percent was from TVE. 25 percent from hydraulic mobilization effects. and 3 percent from dissolution of residuals. Confirmatory soil sampling showed an average reduction of residual contamination by 93.4 percent in comparison to the concentration of residuals prior to the secondary recovery. For the lest cell, a combined total solvent recovery of 99.6 percent was achieved. This high recovery exceeded DNAPL recoveries expected or achieved in other field‐scale attempts.
Low‐Flow Purging and Sampling of Ground Water Monitoring Wells with Dedicated Systems
Authors: Puls Robert W. , Paul Cynthia J.
Published: February 2007

A field study was conducted to assess purging requirements for dedicated sampling systems in conventional monitoring wells and for pumps encased in short screens and buried within a shallow sandy aquifer. Low‐flow purging methods were used, and wells were purged until water quality indicator parameters (dissolved oxygen, specific conductance, turbidity) and contaminant concentrations (chromate, trichloroethylene, dichloroethylene) reached equilibrium. Eight wells, varying in depth from 4.6 to 15.2 m below ground surface, were studied. The data show that purge volumes were independent of well depth or casing volumes. Contaminant concentrations equilibrated with less than 7.5 I. of purge volume in all wells. Initial contaminant concentration values were generally within 20 percent of final values. Water quality parameters equilibrated in less than 10 L in all wells and were conservative measures for indicating the presence of adjacent formation water. Water quality parameters equilibrated faster in dedicated sampling systems than in portable systems and initial turbidity levels were lower.
The Occurrence of Agricultural Chemicals in Illinois' Rural Private Wells: Results from the Pilot Study
Authors: Mehnert E. , Schock S.C. , Earnhardt M.L. , Caughey M.E. , Chou S.F.J. , Dey W.S. , Dreher G.B. , Ray C.
Published: February 2007

Water samples from 240 private wells in rural Illinois were collected over one year and analyzed for 39 agricultural chemicals. Sampling was conducted to provide preliminary information to refine a plan for a statewide survey of the agricultural chemical contamination of rural private wells. Wells were sampled according to a stratified random sampling plan that included four classes of depth lo the uppermost aquifer material and two classes of well type. Depth lo uppermost aquifer material was defined as the depth from ground surface to a geologic material that, if saturated, could he used as an aquifer.

Occurrence, defined as the presence of one or more target analytes in a well water sample above some specified concentration, was shown to be higher in large‐diameter bored or dug wells than in small‐diameter drilled wells. For small‐diameter wells, occurrence generally decreased as the depth to the uppermost aquifer material increased, In addition, depth to the uppermost aquifer material could be used to predict the occurrence of some individual agricultural chemicals, such as nitrate and atrazine, but could not be used to predict the occurrence of pielorarn or pesticides in small‐diameter wells.

Of the 39 target analytes, 10 were detected at concentrations exceeding their respective minimum reporting levels. Nitrate and atrazine were the only compounds found at concentrations exceeding their respective maximum contaminant levels (MCLs) or U.S. EPA lifetime health advisory limits (HAI.s).

A nonparametric statistical technique, contingency table analysis, identified factors associated with the occurrence of agricultural chemicals in three of the file study areas. Elevated specific conductance (>500 μmhos/cm) of the sampled water was strongly associated with the occurrence of agricultural chemicals. This association was common to all three study areas analyzed. Identification of the source of the specific conductance could help identify the dominant pathway for transport of agricultural chemicals to ground water.
Organic Acid Derivatization Techniques Applied to Petroleum Hydrocarbon Transformations in Subsurface Environments
Authors: Barcelona Michael J. , Lu Jie , Tomczak Daniel M.
Published: February 2007

Evidence for the natural microbial remediation of subsurface fuel contamination situations should include identification and analysis of transformation or degradation products. In this way. u mass balance between fuel constituents and end products may be approached to monitor cleanup progress. Application of advanced organic acid metabolite derivatization techniques to several known sites of organic compounds and fuel mixture contamination provide valuable information on the pathways and progress of microbial transformation. Good correlation between observed metabolites and transformation pathways of aromatic fuel constituents were observed at the sites.
Handheld Double Packer Equipment for Water Sampling and Hydraulic Measurements in Deep Boreholes
Authors: Laaksoharju Marcus , Ahonen Lasse , Blomqvist Runar
Published: February 2007

The need 10 characterize deep and shallow bedrock hydrogeologic conditions in remote terrain encouraged the development of an inexpensive, last, and easily transporrable double packer sampler. The principal objective was to combine water sampling and hydraulic measurement with the same equipment. Unconventional construction that does not create any large hydraulic pressure differences in the equipment allows light and inexpensive standard materials and components to be used. The low cost, lightweight equipment can thus be operated by a single person.

The equipment is based on the principle of using soft, hydraulically expandable packers that isolate the required section of the borehole. The inflation and deflation of the packers is controlled by a single tube, through which the water sample is also withdrawn. The uppermost part of the tube branches into two tubes; the pumping action is generated by cyclic pressure pulses applied to one of these tubes.

The equipment has mainly been used in narrow 1,8‐inch (46 mm) diameter boreholes down to a depth of about 3280 feet (1000 m); versions capable of operating in larger boreholes and with higher pump capacity have also been constructed. At one sampling site, the chemical composition of water from an isolated fracture zone was compared with open hole water at the same depth. The water from the fracture had a different chemical composition compared with the mixed water sample from the open hole. To collect representative ground water samples, double packers and long pumping limes are required.

The equipment characterizes both the hydraulically conductive bedrock structures and the chemical compositions of bedrock ground water. Through comparison to K‐values and chemical constituents in other portions of the borehole, the collected data can be used to estimate transport pathways, aquifer yield, travel times, and ground water evolution. The range of hydraulic conductivity measured with the equipment in association with this research was 10‐10 to 10‐7 m/s.
Remediation of Dissolved BTEX Through Surface Application: A Prototype Field Investigation
Authors: O'Leary Katherine E. , Barker James F. , Gillham Robert W.
Published: February 2007

The feasibility of surface application for remediating monoaromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylenes — termed BTEX as a croup) dissolved in ground water under field conditions was investigated at a site within Canadian Forces Base. Borden. Ontario. The surface area was 25 m2 and underlain by 3 to 3.5 m of unsaturated sands soil. For periods of at least 216 hours, between 43 and 72 cm/d of water containing BTEX at concentrations that averaged between 8 and 11 mg/L were continuously applied by drip irrigation. Nitrogen was added to the soil as a nutrient for the final third of the investigation.

Before the applied water reached the water table. BTEX mass losses ranged from of to essentially KM) percent. Less than 6 percent of the BTEX mass losses could be attributed to volatilization from the unsaturated soil. The remaining BTEX mass losses were attributed to biodegradation, mostly in the top 50 cm of the soil, which contained more inorganic nitrogen and organic carbon than the deeper soil. Biodegradation rates increased with applied concentration, nitrogen addition, and exposure to BTEX. Benzene concentrations in ground water attained compliance with Canadian and American drinking water standards only after nitrogen application.
The Electromagnetic Borehole Flowmeter: Description and Application
Authors: Young Steven C. , Pearson Hubert S.
Published: February 2007

Borehole flowmeters are downhole tools that measure axial flow in a well or borehole. Desirable flowmeter characteristics include low detection limit, a wide range of operation, accuracy, durability, reliable performance, and a small diameter and length. The recently developed electromagnetic (F.M) flowmeter has these trails. The first portion of this paper presents the MM flowmeter design, provides laboratory calibration data, and compares the performance characteristics of MM flowmeters 10 those of impeller and thermal pulse flowmeters. The second portion of the paper discusses applications of the MM flowmeter.