Monitoring of Water and Contaminant Migration at the Groundwater-Surface Water Interface (ER200422). Final Cost and Performance Report
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Abstract : The overall objective of this project was to field demonstrate and evaluate the effectiveness of two technologies for characterizing coastal contaminate migration. The specific objectives of this demonstration were to demonstrate (1) that the Trident probe can be used to help delineate areas where groundwater seepage is occurring and Contaminant of Concern concentrations in those areas, (2) that the UltraSeep system can be used to quantify the flow of groundwater and concentration of contaminants that may be impinging on the surface water system, (3) the technology to end-users to determine the utility of these tools for making decisions at DoD coastal landfills and hazardous waste sites, and (4) the quantification of the costs associated with the operation of each technology. The first demonstration was at Naval Support Activity Panama City. The Trident probe was used successfully to identify areas of groundwater discharge from the site to the surface waters of St. Andrews Bay, and the UltraSeep was used successfully to quantify groundwater discharge rates and volatile organic compound (VOC) discharge concentrations in two discharge zones identified with the Trident probe. The second demonstration was performed at the former Naval Training Center Orlando. The Trident probe successfully identified areas of groundwater discharge from the site to the surface waters of Druid Lake and the UltraSeep successfully quantified groundwater discharge rates and VOC discharge concentrations in two discharge zones identified with the Trident probe. The cost analysis indicated that the cost of an integrated Trident probe/UltraSeep survey is expected to be on the order of $120K, which represents a cost savings of about 42% relative to the estimated cost for the baseline technology of about $210K.Keywords:
Groundwater discharge
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The nature and extent of a trichloroethene (TCE) groundwater plume at the southern portion of the U.S. Department of Energy Portsmouth Gaseous Diffusion Plant near Piketon, Ohio, requires the use of multiple remediation methods and approaches for long-term corrective actions and short-term flexibility to contain and reduce groundwater contamination. Interim source control actions included closure in the early 1990s of landfills identified as the primary sources of the contaminated groundwater. The unlined landfills were closed by installing bentonite barrier walls and groundwater collection trenches for groundwater contamination source control and installing multi-layer landfill caps to reduce infiltration. In 1994, a barrier wall was installed along the southern boundary of the site to prevent plume off-site migration. The South Barrier Wall, installed to bedrock by deep soil mixing using a tandem auger system, was designed to be effective for 5-7 years while final groundwater corrective actions were investigated for implementation. The selected final remedy for the groundwater plume was source isolation using barrier walls and groundwater interceptor trenches and plume remediation using an innovative phytoremediation technology. The phytoremediation corrective action was implemented in phases in 2002 and 2003 by planting approximately 28 acres (0.1 sq. km) of hybrid poplar trees in a trench and sand-pipe design within the plume area. Groundwater monitoring data in 2002-2003 from the southern site boundary showed that TCE concentrations were increasing in many of the monitoring wells. These monitoring results indicated that the TCE groundwater plume was close to moving off-site at the center and west end of the South Barrier Wall. Even though the phytoremediation has been implemented, effective remediation might not start until the trees reach a more mature state. In addition, the placement of the trees may not fully contain the very leading edge of the plume.
Groundwater Pollution
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This report presents the results of groundwater and vadose zone monitoring and remediation for fiscal year 1999 on the US. Department of Energy's Hanford Site, Washington. Water-level monitoring was performed to evaluate groundwater flow directions, to track changes in water levels, and to relate such changes to evolving disposal practices. Measurements for site-wide maps were conducted in June in past years and are now measured in March to reflect conditions that are closer to average. Water levels over most of the Hanford Site continued to decline between June 1998 and March 1999. The most widespread radiological contaminant plumes in groundwater were tritium and iodine-129. Concentrations of carbon-14, strontium-90, technetium-99, and uranium also exceeded drinking water standards in smaller plumes. Cesium-137 and plutonium exceeded standards only near the 216-B-5 injection well. Derived concentration guide levels specified in US Department of Energy Order 5400.5 were exceeded for plutonium, strontium-90, tritium, and uranium in small plumes or single wells. Nitrate and carbon tetrachloride are the most extensive chemical contaminants. Chloroform, chromium, cis-1,2dichloroethylene, cyanide, fluoride, and trichloroethylene also were present in smaller areas at levels above their maximum contaminant levels. Metals such as aluminum, cadmium, iron, manganese, and nickel exceeded their maximum contaminant levels in filtered samples from numerous wells; however, in most cases, they are believed to represent natural components of groundwater. ''Resource Conservation and Recovery Act of 1976'' groundwater monitoring continued at 25 waste management areas during fiscal year 1999: 16 under detection programs and data indicate that they are not adversely affecting groundwater; 6 under interim status groundwater quality assessment programs to assess contamination; and 2 under final status corrective-action programs. Another site, the 120-D-1 ponds, was clean closed in fiscal year 1999, and monitoring is no longer required. Groundwater remediation in the 100 Areas continued with the goal of reducing the amount of chromium (100 K, D, and H) and strontium-90 (100 N) reaching the Columbia River. The objective of two remediation systems in the 200 West Area is to prevent the spread of carbon tetrachloride and technetium-99/uranium plumes. Groundwater monitoring continued at these sites and at other sites where there is no active remediation. Subsurface source characterization and vadose zone monitoring, soil-vapor monitoring, sediment sampling and characterization, and vadose zone remediation were conducted in fiscal year 1999. Baseline spectral gamma-ray logging at two single-shell tank farms was completed, and logging of zones at tank farms with the highest count rate was initiated. Spectral gamma-ray logging also occurred at specific retention facilities in the 200 East Area. These facilities are some of the most significant potential sources of remaining vadose zone contamination. Finally, remediation and monitoring of carbon tetradoride in the 200 West Area continued, with an additional 972 kilograms of carbon tetrachloride removed from the vadose zone in fiscal year 1999.
Hanford Site
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This report describes the groundwater monitoring plan for the 216-A-29 ditch on the Hanford Site. This document presents a groundwater monitoring plan, under Resource Conservation and Recovery Act of 1976 (RCRA) regulatory requirements found in WAC 173-303-400, and by reference, requirements in 40 CFR 265.93 (d)(6) for the 216-A-29 Ditch (A-29 Ditch) in the Hanford Site's 200 East Area. The objectives of this monitoring plan are to determine whether any hazardous constituents are detectable in the groundwater beneath the ditch. The groundwater monitoring network described in this plan includes 10 RCRA-compliant wells to monitor the aquifer in the immediate vicinity of the A-29 Ditch. Groundwater assessment activities have been conducted at the A-29 Ditch, the result of elevated specific conductivity and total organic halogens (TOX). A groundwater assessment report (Votava 1995) found that no hazardous constituents had impacted groundwater and the site returned to interim-status indicator-parameter/detection monitoring. This plan describes the process and quality objectives for conducting the indicator-parameter program. The site will be sampled semiannually for indicator parameters including pH, specific conductance, TOX, and total organic carbon. Site-specific parameters include tritium and ICP metals. These constituents, as well as anions, alkalinity, and turbidity will be sampled annually. Groundwater elevations will be recorded semiannually.
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This report presents the results of groundwater and vadose zone monitoring and remediation for fiscal year 2000 on the U.S. Department of Energy's Hanford Site, Washington. The most extensive contaminant plumes are tritium, iodine-129, and nitrate, which all had multiple sources and are very mobile in groundwater. Carbon tetrachloride and associated organic constituents form a relatively large plume beneath the central part of the Site. Hexavalent chromium is present in smaller plumes beneath the reactor areas along the river and beneath the central part of the site. Strontium-90 exceeds standards beneath each of the reactor areas, and technetium-99 and uranium are present in the 200 Areas. RCRA groundwater monitoring continued during fiscal year 2000. Vadose zone monitoring, characterization, remediation, and several technical demonstrations were conducted in fiscal year 2000. Soil gas monitoring at the 618-11 burial ground provided a preliminary indication of the location of tritium in the vadose zone and in groundwater. Groundwater modeling efforts focused on 1) identifying and characterizing major uncertainties in the current conceptual model and 2) performing a transient inverse calibration of the existing site-wide model. Specific model applications were conducted in support of the Hanford Site carbon tetrachloride Innovative Treatment Remediation Technology; to support the performance assessment of the Immobilized Low-Activity Waste Disposal Facility; and in development of the System Assessment Capability, which is intended to predict cumulative site-wide effects from all significant Hanford Site contaminants.
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Abstract : The Plainville landfill, located in Plainville, Massachusetts, has been the subject of study by several groups in recent years. A contaminant plume, exiting from the southwest corner of the landfill, is contaminating the groundwater downgradient and may affect drinking water wells located there. A two-phase remediation scheme, consisting of an interim overburden air sparging system and a final proposed pump and treat and air sparging system, has been proposed to mitigate the groundwater contaminant plume. This thesis assesses these remediation systems to determine their ability to remediate the contaminants in the groundwater plume. The interim and final proposed air sparging systems were analyzed using existing quarterly reports and a literature review. A MODFLOW groundwater flow model was used to analyze the pump and treat system. These analyses were then compared to the model utilized to design the remediation scheme. Several discrepancies in the design of the remediation scheme were noted as a result of this analysis. First, the presence of till lenses throughout the remediation zone was not addressed. Also, the extraction of water from the competent bedrock layer appears counterproductive. In addition, the air sparging system was not field tested to ascertain the flow pattern in the subsurface. Finally, the installation of the bedrock air sparging wells appears redundant. These discrepancies, however, will only decrease the projected efficiency of the proposed remediation schemes and increase clean up time. Consequently, the results of this study seem to indicate that the proposed remediation scheme is adequately designed.
Air sparging
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Sparging
Overburden
Groundwater Remediation
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Volatile organic compounds (VOCS) were discovered in the soil during routine maintenance work at the AT and T Richmond Works. Upon this discovery, AT and T initiated a soil vapor and hydrogeologic evaluation of the site in order to determine the nature and extent of VOCs in the soil and groundwater. A network of groundwater monitor wells provided the information necessary to set up a groundwater model of the site and evaluate potential configurations for a network of wells designed to establish hydraulic controls and pump groundwater to an above ground treatment system. State and local agencies and the Environmental Protection Agency participated in selection of the pump and treat approach to remediation and in selection of the configuration of the extraction well network. The network consists of twelve 6-inch diameter wells that are completed in a shallow water bearing zone. Four wells located in the groundwater plume near the source will account for the bulk of mass VOC removals. The remaining eight wells are located along the down gradient perimeter of the site. The perimeter wells win establish a hydraulic barrier to off-site migration and will account for further VOC removals.
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Site selection
Soil vapor extraction
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Section 3.0. A discussion of the interpretive assumptions used in evaluating the 1991 assessment data, and detailed descriptions of groundwater quality are presented in Section 4.0. Findings of the 1991 monitoring program are summarized in Section 5.0. Proposed modifications to the groundwater quality monitoring program in the UEFPCHR are presented.
Section (typography)
Fork (system call)
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This report presents the results of groundwater and vadose-zone monitoring for fiscal year (FY) 1996 on the Hanford Site, Washington. Hanford Site operations from 1943 onward produced large quantities of radiological and chemical waste that affected groundwater quality on the site. Characterization and monitoring of the vadose zone during FY 1996 comprised primarily spectral gamma logging, soil-gas monitoring, and electrical resistivity tomography. Water-level monitoring was performed to evaluate groundwater-flow directions, to track changes in water levels, and to relate such changes to evolving disposal practices. Water levels over most of the Hanford Site continued to decline between June 1995 and June 1996. Groundwater chemistry was monitored to track the extent of contamination, to note trends, and to identify emerging groundwater-quality problems. The most widespread radiological contaminant plumes were tritium and iodine-129. Smaller plumes of strontium-90, technetium-99, and plutonium also were present at levels above the U.S. Environmental Protection Agency or State of Washington interim drinking water standards. Uranium concentrations greater than the proposed drinking water standard were also observed. Nitrate, fluoride, chromium, carbon tetrachloride, chloroform, trichloroethylene, and cis-1,2-dichlomethylene were present in groundwater samples at levels above their U.S. Environmental Protection Agency or State of Washington maximum contaminant levels. The nitrate plume is the most extensive. Three-dimensional, numerical, groundwater models were applied to the Hanford Site to predict contaminant-flow paths and the impact of operational changes on site groundwater conditions. Other models were applied to assess the performance of three separate pump-and-treat systems.
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Maximum Contaminant Level
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