Biomedical Engineering Reference
In-Depth Information
Table 5.2. (continued)
Injection Wells
Direct Push
Trenching
Fracturing
Depth of treatment zone
Can be used for any depth
Depth limited by size of rig
used and is very
dependent upon formation
properties
Depths up to 60-70 ft are
often achievable in
unconsolidated media,
though some rigs are
capable of going deeper
Limited to the trench depth.
Depths greater than 80 ft
are generally cost
prohibitive
Limited to drilling
equipment used
Hydraulic conductivity of
treatment zone
Most effective in moderate
to high permeability
conditions
Most effective in high
permeability conditions
Generally trench is filled
with high hydraulic
conductivity media
Fracture zones have high
hydraulic conductivity
Injection point inefficiency
can make flow rates low
even in moderate
permeability zones unless
injections are pressurized
Heterogeneity of treatment
zone
Most effective for low to
moderate heterogeneity
Most effective for low
heterogeneity
Treatment zone
homogenized by
emplacing homogenous
media in trench
Homogenous media
emplaced in fractures
Well efficiency (flow rate
per unit head) often much
higher than direct-push
points, which allows larger
volume injections with less
pressure, leading to less
preferential flow during
injection
Injection point inefficiency
leads to a higher degree of
preferential flow for a given
flow rate in heterogeneous
formations relative to
injection wells
Groundwater velocity
Low groundwater
velocities will minimize
downgradient impact of
electron donor
emplacement
Low groundwater
velocities will minimize
downgradient impact of
electron donor
emplacement
Trench can be designed to
allow for adequate
treatment time depending
on groundwater velocity
Low groundwater
velocities will minimize
downgradient impact of
electron donor
emplacement
High groundwater
velocities will limit lateral
impact of electron donor
emplacement
High groundwater
velocities will limit lateral
impact of electron donor
emplacement
High groundwater
velocities will limit lateral
impact of electron donor
emplacement
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