18 research outputs found
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Proposed experiment for SnCl{sub 2} treatment of Outfall 200 for the purpose of mercury removal from East Fork Poplar Creek, Y-12 Plant, Oak Ridge, Tennessee
Identification and treatment/elimination of point sources of mercury (Hg) to East Fork Poplar Creek (EFPC) within the Y-12 Plant have reduced base flow mercury concentrations considerably; but, after all such actions are completed, nonpoint sources will continue to add mercury to the creek. Studies conducted in 1996 on the use of air stripping to remove elemental mercury from Outfall 51, a mercury-contaminated natural spring, demonstrated that the addition of trace concentrations of stannous chloride (SnCl{sub 2}) converted a large fraction of the dissolved mercury in the outfall to elemental mercury, which could subsequently be removed by air stripping. Dissolved mercury is the dominant form in EFPC at the north/south (N/S) pipes, where it emerges from the underground storm drain network. More than 50% of that mercury is capable of being rapidly reduced by the addition of a 3--5 fold molar excess of stannous chloride. Upon conversion to the volatile gaseous (elemental) form, mercury would be lost across the air-water interface through natural volatilization. EFPC within the Y-12 Plant is shallow, turbulent, and open to sunlight and wind, providing conditions that facilitate natural evasion of volatile chemicals from the water. Preliminary calculations estimate that 75% or more of the elemental mercury could be removed via evasion between the N/S pipes and the Y-l2 Plant boundary (Station 17). Alternatively, elemental mercury might be removed from EFPC in a short reach of stream below the N/S pipes by an in-situ air stripping system which bubbles air through the water column. The purpose of these proposed experiments is to test whether natural volatilization or in-situ air stripping may be used to further reduce baseflow concentrations of mercury in EFPC. Results of this experiment will be useful for understanding the transport and fate of other volatile chemicals in the upper reaches of EFPC
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Mercury and Methylmercury Relationships in Contaminated Streams the Southwestern U.S.A.
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Evaluation of the environmental effects of stormwater pollutants for Oak Ridge National Laboratory
Despite Best Management Practices (BMP), total suspended solids (TSS) and oil and grease (O and G) concentrations in stormwater runoff frequently have been above the National Pollutant Discharge Elimination System (NPDES) Permit effluent limits at ORNL. Although the effects of stormwater pollutants to aquatic ecosystems are of concern regionally and nationally, NPDES permit violations at ORNL are best addressed on a site-specific basis. This document explores several key questions to determine whether the TSS and O and G noncompliances at ORNL are primarily a regulatory problem (i.e., Category 1 and 2 effluent limits are neither reasonably achievable nor effective in achieving environmental protection), or a legitimate ecological concern that will require effective remediation. The three tasks outlined in the study plan were to (1) clarify the degree of TSS and O and G noncompliances at ORNL, (2) provide guidance as to appropriate limits for TSS and O and G in Category 1 and 2 discharges, and (3) provide information about the effectiveness of possible mitigation or remediation measures for TSS and O and G in stormwater releases, assuming that such measures are needed for one or more ORNL Category 1 or 2 outfalls
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Evaluation of fish kills during November 1986 and July 1987 in upper East Fork Poplar Creek near the Y-12 Plant
The Environmental Sciences Division (ESD) investigated two fish kills that occurred on November 21, 1986, and July 9, 1987, in upper East Fork Poplar Creek at the outfall of New Hope Pond (NHP) below the Oak Ridge Y-12 Plant. Investigative procedures included sampling of water at the inlet and outfall of NHP for water quality, examination of operating procedures at the Y-12 Plant and in the biomonitoring program that may have adversely affected the fish populations, review of results of concurrent ambient toxicity tests of the inlet and outfall water of NHP, autopsy investigations of the cause of death of the stonerollers, and laboratory experimentation to evaluate potential causes. The investigations revealed that the cause of death was bacterial hemorrhagic septicemia caused by Aeromonas hydrophila, which is a stress-mediated disease. The specific stressor responsible for the outbreak of the disease was not identified. Several possible stresses were indicated, including elevated concentrations of mercury and chlorine, excessive electroshocking activity, and elevated levels of the pathogen. Cumulative stress due to the combination of several factors was also suggested. Elevated temperatures and overcrowding may have enhanced the spread of the epizootic but were not the primary causes. The impact on the stoneroller population below NHP was not ecologically significant. 23 refs., 3 figs., 12 tabs
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Oak Ridge Gaseous Diffusion Plant Biological Monitoring and Abatement Program for Mitchell Branch
A proposed Biological Monitoring and Abatement Program (BMAP) for the Oak Ridge Gaseous Diffusion Plant (ORGDP; currently the Oak Ridge K-25 Site) was prepared in December 1986, as required by the modified National Pollutant Discharge Elimination System (NPDES) permit that was issued on September 11, 1986. The effluent discharges to Mitchell Branch are complex, consisting of trace elements, organic chemicals, and radionuclides in addition to various conventional pollutants. Moreover, the composition of these effluent streams will be changing over time as various pollution abatement measures are implemented over the next several years. Although contaminant inputs to the stream originate primarily as point sources from existing plant operations, area sources, such as the classified burial grounds and the K-1407-C holding pond, can not be eliminated as potential sources of contaminants. The proposed BMAP consists of four tasks. These tasks include (1) ambient toxicity testing, (2) bioaccumulation studies, (3) biological indicator studies, and (4) ecological surveys of the benthic invertebrate and fish communities. BMAP will determine whether the effluent limits established for ORGDP protect the designated use of the receiving stream (Mitchell Branch) for growth and propagation of fish and aquatic life. Another objective of the program is to document the ecological effects resulting from various pollution abatement projects, such as the Central Neutralization Facility
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The Oak Ridge Y-12 Plant biological monitoring and abatement program for East Fork Poplar Creek
In May 1985, a National Pollutant Discharge Elimination System permit was issued for the Oak Ridge Y-12 Plant, a nuclear weapons components production facility located in Oak Ridge, Tennessee, and operated by Martin Marietta Energy Systems, Inc., for the US Department of Energy. As a condition of the permit, a Biological Monitoring and Abatement Program (BMAP) was developed to demonstrate that the effluent limitations established for the Oak Ridge Y-12 Plant protect the classified uses of the receiving stream (East Fork Poplar Creek), in particular, the growth and propagation of fish and aquatic life, as designated by the Tennessee Department of Health and Environment. A second purpose for the BMAP is to document the ecological effects resulting from implementation of a water pollution control program that will include construction of nine new wastewater treatment facilities over the next 4 years. Because of the complex nature of the effluent discharged to East Fork Poplar Creek and the temporal and spatial variability in the composition of the effluent (i.e., temporal variability related to various pollution abatement measures that will be implemented over the next several years and spatial variability caused by pollutant inputs downstream of the Oak Ridge Y-12 Plant), a comprehensive, integrated approach to biological monitoring was developed for the BMAP. 39 refs., 5 figs., 8 tabs
Macrolevel Model Development for Safety Assessment of Road Network Structures
Traffic analysis zones are often delineated by the existing street network. This practice may result in a considerable number of crashes on or near zonal boundaries. Although the traditional macrolevel approach to crash modeling assigns zonal attributes to all crashes that occur within the zonal boundary, this paper acknowledges the inaccuracy resulting from relating crashes on or near the boundary of the zone to merely the attributes of that zone. This paper proposes a novel approach to account for the spatial influence of neighboring zones on crashes that occur specifically on or near the zonal boundaries. Predictive models for pedestrian crashes per zone were developed with a hierarchical Bayesian framework and with separate predictor sets for boundary and interior (nonboundary) crashes. The hierarchical Bayesian model that accounted for spatial autocorrelation was found to have better goodness-of-fit measures than did models that had no specific consideration for crashes located on or near the boundaries. In addition, the models were able to capture some unique predictors associated explicitly with interior and boundary-related crashes. For example, two variables, total roadway length with a posted speed of 35 mph and long-term parking cost, were not statistically significant from zero in the interior crash model but were significantly different from zero at the 95% level in the boundary crash model