Abstract
Geo-environmental hazards associated with abandoned borrow pits in
Nigeria are on the rise and a major concern to citizens,
environmentalists and governments. Several highway failure spots are
directly linked to the action of erosion initiated by active or
abandoned (inactive) borrow pits situated close to the roads. This study
examines the negative environmental impacts of the continuous removal of
soil from borrow pits in some areas of Ado Ekiti, Nigeria. Four borrow
pits were selected; two active sites and two abandoned sites. At
inception, topographical and 3-Dimensional maps of the borrow pits were
drawn and modelled. The area of the borrow pits and the volume of
overburden excavated soils were calculated. The soil over burden
pressure at the average height of the borrow pits were measured. The
active borrow pit sites were checked again after two months to know the
difference in the volume of overburden removed in the pit for that
period. The volume of soil removed from borrow pit 1 (Active site), 2
(Active site), 3(Abandoned) and 4 (Abandoned) are 37000 m3, 34000 m3,
114000 m3 and 81000 m3 respectively. Environmental assessment of the
study area through photographs showed prevalence of landslides, erosion,
flooding, vegetation removal and structural failure. The volume of soil
overburden removed from the abandoned borrow pit is more than the volume
extracted from the active sites, this significant change in the value of
overburden removed causes significant change to the terrain of the
borrow pit. Some measures were then suggested to curb the problem
occurring from the uncontrolled and indiscriminate borrow pits
excavation thereby improving environmental sustainability. This study
serves as a basis for government to put in place laws that help protect
the environment from indiscriminate mining of borrow pits.