Abstract:
The broad objective of the study was to investigate potential environmental risks of
Eburru wellhead geothermal power plant on the local community. Primary data on
perception of the local community towards the potential risks was collected through
focus group discussions, interviews and structured questionnaires. The questionnaires
were administered to ninety five (95) households residing in four villages neighbouring
the power plant in Eburru location, Gilgil Sub-county. Historical data on brine
chemistry, noise and hydrogen sulphide (H2S) gas was also reviewed and analyzed.
Processing and presentation of primary data was achieved using Microsoft Excel. Data
on brine chemistry, noise and H2S gas was analyzed by making reference to the relevant
environmental standards. Any parameter that exceeded the maximum recommended
limit was considered to present an environmental risk. Results have been presented in
form of frequencies, tables, bar graphs and pie charts. The study found out that the local
community consider Eburru wellhead power plant to impact them negatively. In terms
of severity of the impacts, the highest ranked risk was associated with H2S gas odour,
followed by noise emission, atmospheric venting of geothermal fluids and brine
discharge. The chemistry of the brine did not meet the recommended limit for effluent
discharge into the environment. The ambient H2S gas levels measured outside the
boundary of the power plant exceeded the 24 hour average tolerant limit of 0.0355 ppm
up to a distance of 100 m in the northern direction. Ambient noise levels exceeded the
tolerable limit of 35 dB (A) up to a distance of 1100 m from the boundary of the power
plant. The ambient noise level does not warrant hearing impairment. Atmospheric brine
spray can cause damage to the surrounding vegetation due to elevated levels of boron.
Relocation of the affected persons within a radius of 1.5 km from the boundary of the
power plant is recommended. Other measures include use of engineering measures to
reduce noise, H2S and atmospheric spray of brine, installation of a reinjection system
and stepping up education and awareness among the locals. Precautionary principle
should be considered in the initial design of future geothermal power plants. Further
research should consider studies on diurnal variation of H2S gas emission,
epidemiological studies to determine real impacts of noise and H2S on the health of the
locals and an experiment to determine the fall out area of atmospheric brine spray and
deposition.
