Quantitative Risk Assessment of Groundwater pH during Seismic Exploration in Sagbama, Niger Delta, Nigeria

Quantitative Risk Assessment of Groundwater pH during Seismic Exploration in Sagbama, Niger Delta, Nigeria were investigated with dynamite energy source. A total amount of 116,349.2 kg dynamite was detonated in 60, 398 source point in an area of 771.26 square kilometers of Sagbama area. The energy source was the high explosive dynamite (trinitrotoluene) and 6m Electric Detonators loaded in 5 hole pattern source array. Eleven boreholes was used to study the impact of the dynamite shots in Sagbama. The American Water Works Association method was used in the analysis of pH. A control sample was taken from the borehole stations by sampling a day before detonation of dynamite. Subsequently, sampling was carried out a day after dynamite detonation and then, on a forth-nightly basis. The pH range was 7.47 – 7.70. These Variations of the pH of the water sample test values in comparison with the values of the control samples were not significant enough to be said that there was any groundwater contamination. The shattering property (brisance) of the dynamite resulted in the crushing of some amount of the sediment particles. Computation of the grain size distribution curve parameters yielded a permeability value of 3.24 cm/sec. The representative lithology of Sagbama area as revealed by the borehole logging showed that they are mainly non-plastics also categorized as cohensionless sands. The presence of silty sands at 4 to 5m depths could be an obstruction to infiltration of contaminants from dynamite detonation. However, the pH of the groundwater did not exceed the tolerance or compliance limit specified by the Federal Ministry of Environment, Housing and Urban Development.