The radiological assessment of the impact of municipal solid waste dumpsite on soil and groundwater in the vicinity of dumpsite was investigated using electrical resistivity method and gamma ray spectroscopy. The research aims at determining the extent of contamination on the soil, groundwater and evaluation of the radioactivity concentrations in soil and groundwater. Twenty (20) samples of soil were taken on the active and dormant parts of the dumpsite were analyzed. Fourteen (14) Vertical Electrical Soundings were also carried out on and around the dumpsites. Based on the results obtained using the VES, the subsurface information revealed the lithological units of the subsurface and the extent the leachate has migrated through the sand available on the dumpsite vicinity. Leachate has penetrated into depths of about 30m into the groundwater aquifer. The radiological assessment of the radionuclides 40K, 226Ra and 228Ra obtained for the active dumpsite revealed the absorbed dose rates, annual effective dose rates for the active dumpsite ranged from (313.35 ̶ 1670.29) nGy/h with the mean of 926.33 nGy/h and (0.001 ̶ 0.31) mSv/y with the mean of 0.15 mSv/y. The mean value for the radium equivalent (211.97) is lower than the permissible limit 370. The absorbed dose rates, annual effective dose rates for the dormant dumpsite ranged from (395.97 ̶ 1038.38) Bq/kg with the mean of (813.15 nGy/h and 2.43 ̶ 6.37) μSv/y with the mean of 0.14μSv/y. The mean value for the radium equivalent (185.71) is lower than the permissible limit 370. These results are compared to those reported for other research done on dumpsites, and the dormant part of the dumpsite was found lower than the standard and that of the active dumpsite pose serious threat to the wellbeing of the people near or working there. Results reveals that soil on the active part of the dumpsite have been contaminated by radioactive materials all through the dumpsite area.
Key words: Vertical Electrical Sounding, Leachate, Gamma-Ray spectrometry, Radionuclides, Mean Absorbed Dose Rate.
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