MIL-HDBK-1005/16
are modeled after the Federal classifications, are presented in
Table 16. Refer to Groundwater Recharge Using Waters of Impaired
Quality, National Research Council, 1994.
9.3.2.1
Applications Guidance. Recharge wells are potentially
applicable in areas where surface soils are not available, land
is too costly, wastewater flows are excessive, wastewater quality
is unacceptable for infiltration basins, drinking water wells are
in close proximity to wastewater treatment facilities, or vadose
zones have restricting layers or undesirable chemicals that could
leach out. For these conditions, among others, injection wells
are an option. Domestic and industrial wastewater injection
wells typically recharge brackish to saline water aquifers or
aquifers of otherwise poor water quality. The injection wells
may also be used to develop a barrier to saltwater intrusion in
coastal areas using highly treated wastewater. Wastewater to be
used for underground injection undergoes various levels of
pretreatment, up to and including advanced wastewater treatment
processes. The interaction between the injection water and the
native groundwater, including a full characterization of each,
should be well understood. This characterization is typically
based on Federal (and often state) drinking water standards.
9.3.2.2
General Design Guidance. Several general design
criteria should be evaluated when designing an injection well
system and before construction:
a)
Well completion details, including type of casing
material on well and screen, if used (e.g., carbon steel,
stainless steel, polyvinylchloride [PVC], etc.), approximate
casing setting depths, casing diameters (generally designed for
fluid velocities of 8 fps [2.4 m/s] or less), necessity of tubing
and packer, and whether well is screened or open borehole.
b)
Pump station design.
c)
Wellhead piping and appurtenances (including flow
and pressure monitoring equipment).
d)
A hydrogeologic drilling and testing program to
collect and analyze aquifer data (e.g., packer testing, coring,
specific capacity testing, geophysical logging program, and water
quality sampling).
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