Azura-Edo Independent Power Plant Environmental Impact ... - IFC

The results of the inorganic and organic parameters from the groundwater
samples collected are provided below.
Groundwater Quality
Groundwater was sampled at three boreholes close to the Project site, namely
two Ihovbor-Evboeka community boreholes and the Orior-Osemwende
community borehole and results are presented in Table 4.2. The pH value was
recorded at 5.2 and 5.4 at the Ihovbor-Evboeka community boreholes and 5.1
(wet season) at the Orior-Osemwende community borehole. These values lie
outside of the WHO optimal range for drinking water (between 6.9 and 9.5)
(WHO, 2007) and the recommended FMEnv range for drinking water quality
(Annex B). The in situ temperature of the groundwater at the Ihovbor-Evboeka
community boreholes was measured at 28.4 and 24.5 ºC. The temperature at
the Orior-Osemwende borehole was recorded at 23.5 ºC.
The results of the analysis of the other parameters are presented below.
• Salinity and Conductivity. The conductivity values were recorded at 18.4, 23.2
and 43.6 µS/cm at the Ihovbor-Evboeka (Borehole 1) and Ihovbor-Evboeka
(Borehole 2) and Orior-Osemwende communities respectively. The results are
within the FMEnv standards of 1000 µS/cm and below the WHO and EU
maximum upper limit for drinking water of 250 µS/cm (Lenntech, 2011). The
salinity of the groundwater at the Ihovbor-Evboeka community borehole was
recorded at 0.007 percent during the dry season and 0.008 percent during the
wet season. Salinity was measured as 0.020 percent at the Orior-Osemwende
community (wet season).
• Dissolved Oxygen and Oxygen Demand. The dissolved oxygen content of the
water recorded at Ihovbor-Evboeka was 2.15 (dry season), 4.20 (wet season) and
at Orior-Osemwende community was 4.20 mg/l (wet season). All dissolved
oxygen values fall below the FMEnv limit of 7.50mg/l (FEPA, 1991). The
Biological Oxygen Demand (BOD) of the groundwater was less than 1.0 mg/l
during both sampling surveys. In addition, the Chemical Oxygen Demand
(COD) at the Ihovbor-Evboeka borehole was recorded at 8.0 mg/l (Borehole 1,
dry season) and fell below 1.0 mg/l during the (Borehole 2, wet season).
• Turbidity and Dissolved and Suspended Solids. The turbidity of the
groundwater was recorded at 1.0 NTU (1) at both boreholes. This falls just
outside the WHO drinking water standards for turbidity (