Environmental Engineering Reference
In-Depth Information
resources with an associated landscape component that contributes to their signifi-
cance, such as a sacred landscape or historic trail. The potential for indirect impacts
(e.g., vandalism, unauthorized collection) would be greater during the operations and
maintenance phase compared to prior phases due to its longer duration.
Ecological Resources
Most impacts on ecological resources (vegetation, wildlife, aquatic biota, special sta-
tus species, and their habitat) would be less during the operations and maintenance
phase than for the exploration and drilling and construction phases because no new
drilling or construction activities would take place. However, operations and mainte-
nance activities have the potential to affect ecological resources mainly by reducing
the acreage for foraging and migrating animals, fragmenting habitat, and creating
noise at the project site during the life cycle of the project (which could last up to 50
years). Some of these impacts could be significant. Increased human activity also
increases the risk of fire, especially in arid or semiarid areas. Application of herbi-
cides to control vegetation along access roads, buildings, and power plant structures
would increase the risk of wildlife exposure to contaminants.
Water Resources
Impacts on water resources during the operations and maintenance phase result
mainly from the water demands associated with operating a geothermal power plant.
Water resources during operations would be needed for replenishment of the geo-
thermal reservoir through reinjection. However, because some water would be con-
sumed by evaporation, additional water would have to be added to the system from
another source. Makeup water to replace the evaporative losses and blowdown in a
water-cooled power plant system would also be needed, depending on the type of
power plant used (e.g., flash steam facilities can lose up to 20% of its cooling water
due to evaporation, but binary plants are nonconsumptive because they use a closed-
loop system). Water can also be lost due to pipeline failures or surface discharge for
monitoring and testing the geothermal reservoir. The availability of water resources
could be a limiting factor in siting or expanding a geothermal development at a given
location. Cooling water or water from geothermal wells that is discharged to the
ground or to an evaporation pond could affect the quality of shallow groundwater
if allowed to percolate through the ground. However, the potential for this type of
impact is considered minor or negligible because the facility would have to comply
with the terms of the discharge permit required by the state.
Land Use
Impacts on land uses during the operations and maintenance phase are an extension
of those that occurred during the exploration and drilling and construction phases.
Although, to some extent, land use can revert to its original uses (e.g., livestock graz-
ing), many other uses (e.g., mining, farming, hunting) would be precluded during the
life span of the geothermal development. Mineral resources would remain available
for recovery, and operations and maintenance activities are unlikely to affect mining
and energy development activities, military operations, livestock grazing, or aviation
on surrounding lands.
