Mapping Subsurface Seepage Flow Patterns in Proximity to a Coal Combustion Residual Landfill Using Electrical Resistivity Tomography

Electrical resistivity tomography data were acquired in proximity to the coal combustion residual landfill in an effort to image and analyze seepage pathways through the shallow residual soil and underlying karsted limestone bedrock. The water table is at a depth of more than 45 m. The most prominent subsurface seepage pathways identified on the acquired electrical resistivity tomography data are located immediately adjacent to the toe of the landfill and are attributed to stormwater run-off. The moisture content of the limestone appears to decrease gradually with increasing distance from the toe of the landfill, suggesting there is also a horizontal component of moisture flow in the subsurface. Shallow limestone with higher moisture content generally underlies or is in close proximity to anthropogenic features such as drainage ditches and clay berms that are designed to channel run-off. At one location, electrical resistivity tomography data were acquired along essentially the same traverse at different times of the year, and the resistivity of shallow limestone overall was lower on the data acquired after heavy rains.

Geophysical Investigation of a Solid Waste Disposal Site Using Integrated Electrical Resistivity Tomography and Multichannel Analyses of Surface Waves Methods

Electrical resistivity tomography survey was deployed at a solid waste landfill in southwest Missouri USA with the intent to map variations in moisture content through the solid waste and underlying subsurface, and to map the top of bedrock. Multichannel analyses of surface waves survey was also deployed to map variations in engineering properties of the solid waste and underlying subsurface, and to constrain the interpretations of top of bedrock. The 2-D resistivity images through the waste suggest rainwater seeps through the cap cover system of the solid waste landfill, and moisture content within the solid waste increases with solid waste burial depth. The resistivity anomalies displayed by the soil and bedrock directly underneath the solid waste suggests a lateral component to moisture infiltrating at the toe of the landfill, which is flowing inward to the base of solid waste structural low. The 1-D shear wave velocity profiles obtained from the multichannel analyses of surface waves survey helped interpret the top of bedrock underneath the solid waste, where top of bedrock is difficult to map using electrical resistivity tomography, as shallow fractured bedrock is moist and displays comparable resistivity values to that of overlying soil. Not surprisingly, the top of bedrock is readily identified on the electrical resistivity tomography profiles in places where subsurface is relatively dry. The deployment of the combined non- invasive, cost and time effective geophysical surveys, along with engineering judgement on available site history data, has reasonably identified potential landfill seepage pathways. The methodology presented could be used in similar site investigation settings.

Characterizing Lake Bottom Sediments Using Marine Geophysical Tools

Missouri is a state with rich karst terrain. Geotechnical evaluation of foundation design for bridges and dams requires an understanding of the characteristics of subsurface geological environment, including sediments, bedrock and benthic habitat. It is crucial that the community empowers itself with the knowledge of the karst system’s characteristics in order to potentially use it as a source of water and drainage, but also to avoid the disaster of building constructions too close to vulnerable land on top of massive karst caverns. Electrical resistivity tomography profiling (underwater cables), and continuous resistivity profiling (towed cable) surveys were conducted to characterize the lake sediments (rock and soil) beneath the man-made Little Prairie Lake, in Central of Missouri State, United States. Electrical resistivity (with marine cables and towed cable) was used to determine variability in the lithology and thickness of sediments (soil and rock) beneath the lake with conjunction of echo sounder in order to calculate water depth. Side scan sonar was used to map the variations in the lithology/nature of exposed lakebed sediments and to locate the potential hazard of trees. On land, electrical resistivity tomography was used with multi-channel analysis of surface wave method to determine sediments, joints, and the depth of bedrock. Analyses of the acquired data revealed the location and orientation of the original stream channels (prior to the construction of the earth fill dam). Underwater electrical resistivity tomography and continuous resistivity profiling determined joints, sediments, and bedrock underneath water bodies. Integrated marine geophysical tools help to evaluate the subsurface prior to any construction project (dam or bridge), are useful in determining the characteristics of lithology (fractured rock, intact rock and soil), and make it possible to map benthic habitat and the submerged potential hazards of trees on the lakebed as well as accurately measuring water depth.

Estimating the economic and social consequences for patients diagnosed with human African trypanosomiasis in Muchinga,Lusaka and Eastern Provinces of Zambia(2004-2014)

Background:Acute human African trypanosomiasis(rHAT)caused by Trypanosoma brucei rhodesiense is associated with high mortality and is fatal if left untreated.Only a few studies have examined the psychological,social and economic impacts of rHAT.In this study,mixed qualitative and quantitative research methods were used to evaluate the socio-economic impacts of rHAT in Mambwe,Rufunsa,Mpika and Chama Districts of Zambia.Methods:Individuals diagnosed with rHAT from 2004 to 2014 were traced using hospital records and discussions with communities.Either they,or their families,were interviewed using a structured questionnaire and focus group discussions were conducted with affected communities.The burden of the disease was investigated using disability adjusted life years(DALYs),with and without discounting and age-weighting.The impact of long-term disabilities on the rHAT burden was also investigated.Results:Sixty four cases were identified in the study.The majority were identified in second stage,and the mortality rate was high(12.5%).The total number of DALYs was 285 without discounting or age-weighting.When long-term disabilities were included this estimate increased by 50%to 462.The proportion of years lived with disability(YLD)increased from 6.4%to 37%of the undiscounted and un-age-weighted DALY total.When a more active surveillance method was applied in 2013-2014 the cases identified increased dramatically,suggesting a high level of under-reporting.Similarly,the proportion of females increased substantially,indicating that passive surveillance may be especially failing this group.An average of 4.9 months of productive time was lost per patient as a consequence of infection.The health consequences included pain,amnesia and physical disability.The social consequences included stigma,dropping out of education,loss of friends and self-esteem.Results obtained from focus group discussions revealed misconceptions among community members which could be attributed to lack of knowledge about rHAT.Conclusions:The social and economic impact of rHAT on rural households and communities is substantial.Improved surveillance and strengthening of local medical services are needed for early and accurate diagnosis.Disease prevention should be prioritised in communities at risk of rHAT,and interventions put in place to prevent zoonotic disease spill over from domestic animals and wildlife.Supportive measures to mitigate the long-term effects of disability due to rHAT are needed.