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. 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.
