Zone of capture analysis for the A/M area of the Savannah River Site

The groundwater of the A/M Area of the Savannah River Site (SRS) is contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) as the result of the past use and disposal of these solvents. For the purpose of remediating this contamination, the A/M Area of the SRS has been divided into three sectors termed the central, northern (or SRL), and southern sectors. The central portion of the A/M Area has had an active remediation system of eleven recovery wells since 1985 and its effectiveness has been evaluated through groundwater modeling. Remediation will soon begin at the northern or SRL sector with a pump and treat system of six wells distributed at four different locations with total pumping of approximately 250 gallons per minute (gpm). The locations and effectiveness of the capture system for each sector has been estimated through groundwater modeling without full consideration of the central recovery system. This report will provide an estimate of the number of recovery wells required for the southern sector and also consider the effects of the current and planned recovery systems for the northern and central plumes. The southern sector contamination (which is defined as the area south of the M-Area basin) has been initially characterized and one recovery well (RWM-16) has been installed, for which an aquifer test was performed. However, to date a recovery well system has not been designed for the southern sector nor has a comprehensive evaluation of the recovery systems for all three sectors been completed. The purpose of this groundwater modeling study is to: (1) determine the location and number of recovery wells necessary to contain or remediate the southern sector, and (2) complete an analysis of the combined central, northern and estimated southern sector remediation so that the interactions of the systems can be determined

Characterizing hydrogeologic heterogeneity using lithologic data

Large-scale (>1 m) variability in hydraulic conductivity is usually the main influence on field-scale groundwater flow patterns and dispersive transport. Incorporating realistic hydraulic conductivity heterogeneity into flow and transport models is paramount to accurate simulations, particularly for contaminant migration. Sediment lithologic descriptions and geophysical logs typically offer finer spatial resolution, and therefore more potential information about site-scale heterogeneity, than other site characterization data. In this study, a technique for generating a heterogeneous, three- dimensional hydraulic conductivity field from sediment lithologic descriptions is presented. The approach involves creating a three-dimensional, fine-scale representation of mud (silt and clay) percentage using a stratified interpolation algorithm. Mud percentage is then translated into horizontal and vertical conductivity using direct correlations derived from measured data and inverse groundwater flow modeling. Lastly, the fine-scale conductivity fields are averaged to create a coarser grid for use in groundwater flow and transport modeling

Relationship between oral declaration on adherence to ivermectin treatment and parasitological indicators of onchocerciasis in an area of persistent transmission despite a decade of mass drug administration in Cameroon

BACKGROUND: Onchocerciasis control for years has been based on mass drug administration (MDA) with ivermectin (IVM). Adherence to IVM repeated treatment has recently been shown to be a confounding factor for onchocerciasis elimination precisely in rain forest areas where transmission continues and Loa loa co-exists with Onchocerca volvulus. In this study, participants’ oral declarations were used as proxy to determine the relationship between adherence to IVM treatment and parasitological indicators of onchocerciasis in the rain forest area of Cameroon with more than a decade of MDA. METHODS: Participants were recruited based on their IVM intake profile with the aid of a semi-structured questionnaire. Parasitological examinations (skin sniping and nodule palpation) were done on eligible candidates. Parasitological indicators were calculated and correlated to IVM intake profile. RESULTS: Of 2,364 people examined, 15.5 % had never taken IVM. The majority (40.4 %) had taken the drug 1–3 times while only 18 % had taken ≥ 7 times. Mf and nodule prevalence rates were still high at 47 %, 95 % CI [44.9–49.0 %] and 36.4 %, 95 % CI [34.4–38.3 %] respectively. There was a treatment-dependent reduction in microfilaria prevalence (r(s) =−0.986, P = 0.01) and intensity (r(s) =−0.96, P = 0.01). The highest mf prevalence (59.7 %) was found in the zero treatment group and the lowest (33.9 %) in the ≥ 7 times treatment group (OR = 2.8; 95 % CI [2.09–3.74]; P < 0.001). Adults with ≥ 7 times IVM intake were 2.99 times more likely to have individuals with no microfilaria compared to the zero treatment group (OR = 2.99; 95 % CI [2.19–4.08], P < 0.0001). There was no clear correlation between treatment and nodule prevalence and intensity. CONCLUSION: Adherence to ivermectin treatment is not adequate in this rain forest area where L. loa co-exists with O. volvulus. The prevalence and intensity of onchocerciasis remained high in individuals with zero IVM intake after more than a decade of MDA. Our findings show that using parasitological indicators, reduction in prevalence is IVM intake-dependent and that participants’ oral declaration of treatment adherence could be relied upon for impact studies. The findings are discussed in the context of challenges for the elimination of onchocerciasis in this rain forest area

Situation analysis of parasitological and entomological indices of onchocerciasis transmission in three drainage basins of the rain forest of South West Cameroon after a decade of ivermectin treatment

BACKGROUND: Community-Directed Treatment with Ivermectin (CDTI) is the main strategy adopted by the African Programme for Onchocerciasis control (APOC). Recent reports from onchocerciasis endemic areas of savannah zones have demonstrated the feasibility of disease elimination through CDTI. Such information is lacking in rain forest zones. In this study, we investigated the parasitological and entomological indices of onchocerciasis transmission in three drainage basins in the rain forest area of Cameroon [after over a decade of CDTI]. River basins differed in terms of river number and their flow rates; and were characterized by high pre-control prevalence rates (60-98%). METHODS: Nodule palpation and skin snipping were carried out in the study communities to determine the nodule rates, microfilarial prevalences and intensity. Simulium flies were caught at capture points and dissected to determine the biting, parous, infection and infective rates and the transmission potential. RESULTS: The highest mean microfilaria (mf) prevalence was recorded in the Meme (52.7%), followed by Mungo (41.0%) and Manyu drainage basin (33.0%). The same trend was seen with nodule prevalence between the drainage basins. Twenty-three (23/39) communities (among which 13 in the Meme) still had mf prevalence above 40%. All the communities surveyed had community microfilarial loads (CMFL) below 10 mf/skin snip (ss). The infection was more intense in the Mungo and Meme. The intensity of infection was still high in younger individuals and children less than 10 years of age. Transmission potentials as high as 1211.7 infective larvae/person/month were found in some of the study communities. Entomological indices followed the same trend as the parasitological indices in the three river basins with the Meme having the highest values. CONCLUSION: When compared with pre-control data, results of the present study show that after over a decade of CDTI, the burden of onchocerciasis has reduced. However, transmission is still going on in this study site where loiasis and onchocerciasis are co-endemic and where ecological factors strongly favour the onchocerciasis transmission. The possible reasons for this persistent and differential transmission despite over a decade of control efforts using ivermectin are discussed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-015-0817-2) contains supplementary material, which is available to authorized users

Zone of capture analysis for the A/M area of the Savannah River Site

The groundwater of the A/M Area of the Savannah River Site (SRS) is contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) as the result of the past use and disposal of these solvents. For the purpose of remediating this contamination, the A/M Area of the SRS has been divided into three sectors termed the central, northern (or SRL), and southern sectors. The central portion of the A/M Area has had an active remediation system of eleven recovery wells since 1985 and its effectiveness has been evaluated through groundwater modeling. Remediation will soon begin at the northern or SRL sector with a pump and treat system of six wells distributed at four different locations with total pumping of approximately 250 gallons per minute (gpm). The locations and effectiveness of the capture system for each sector has been estimated through groundwater modeling without full consideration of the central recovery system. This report will provide an estimate of the number of recovery wells required for the southern sector and also consider the effects of the current and planned recovery systems for the northern and central plumes. The southern sector contamination (which is defined as the area south of the M-Area basin) has been initially characterized and one recovery well (RWM-16) has been installed, for which an aquifer test was performed. However, to date a recovery well system has not been designed for the southern sector nor has a comprehensive evaluation of the recovery systems for all three sectors been completed. The purpose of this groundwater modeling study is to: (1) determine the location and number of recovery wells necessary to contain or remediate the southern sector, and (2) complete an analysis of the combined central, northern and estimated southern sector remediation so that the interactions of the systems can be determined

Defense Waste Processing Facility

The information contained in this report is intended to supplement the original Environmental Impact Statement (EIS) for the Defense Waste Processing Facility (DWPF). Since the original EIS in 1982, alterations have been made to he conceptual process that reduce the impact to the groundwater. This reduced impact is documented in this report along with an update of the understanding of seismology and geology of the Savannah River Site. 6 refs., 2 figs., 2 tabs

Final Report on Testing of Off-Gas Treatment Technologies for Abatement of Atmospheric Emissions of Chlorinated Volatile Organic Compounds

The purpose of this report is to summarize the results of the program for off-gas treatment of atmospheric emissions of chlorinated volatile organic compounds (CVOCs), in particular trichloroethylene (TCE) and perchloroethylene (PCE). This program was funded through the Department of Energy Office of Technology Development`s VOC`s in Non-Arid Soils Integrated Demonstration (VNID). The off-gas treatment program was initiated after testing of in-situ air stripping with horizontal wells was completed (Looney et al., 1991). That successful test expectedly produced atmospheric emissions of CVOCs that were unabated. It was decided after that test that an off-gas treatment is an integral portion of remediation of CVOC contamination in groundwater and soil but also because several technologies were being developed across the United States to mitigate CVOC emissions. A single platform for testing off-gas treatment technologies would facilitate cost effective evaluation of the emerging technologies. Another motivation for the program is that many CVOCs will be regulated under the Clean Air Act Amendments of 1990 and are already regulated by many state regulatory programs. Additionally, compounds such as TCE and PCE are pervasive subsurface environmental contaminants, and, as a result, a small improvement in terms of abatement efficiency or cost will significantly reduce CVOC discharges to the environment as well as costs to United States government and industry

Groundwater modeling of the proposed new production reactor site, Savannah River Site, South Carolina

This report addresses groundwater modeling performed to support the Environmental Impact Statement (EIS) that is being prepared by the Department of Energy (DOE). The EIS pertains to construction and operation of a new production reactor (NPR) that is under consideration for the Savannah River Site (SRS). Three primary issues are addressed by the modeling analysis: (1) groundwater availability, (2) changes in vertical hydraulic gradients as a result of groundwater pumpage, and (3) migration of potential contaminants from the NPR site. The modeling indicates that the maximum pumpage to be used, 1000 gpm, will induce only minor drawdown across SRS. Pumpage of this magnitude will have a limited effect on the upward gradient from the Cretaceous into the Tertiary near Upper Three Runs Creek. Potentiometric surface maps generated from modeled results indicate that horizontal flow in the water table is either towards Four Mile Creek to the north or to Pen Branch on the south. Particle tracking analysis indicates that the primary flow paths are vertical into the Lower Tertiary Zone, with very little lateral migration. Total travel times from the NPR site to the edge of the model (approximately 3 miles) is on the order of 50 years. The flow direction of water in the Lower Tertiary Zone is relatively well defined due to the regional extent of the flow system. The Pen Branch Fault does not influence contaminant migration for this particular site because it is in the opposite direction of Lower Tertiary Zone groundwater flow. 20 refs., 27 figs., 2 tabs