MIL-HDBK-1005/16
a)
Types and quantities of cement to fill annular
space to prevent fluid migration.
b)
Final casing setting depths.
c)
Information to determine if any state or Federal
relief mechanisms are needed to operate the system (e.g., aquifer
d)
Operational testing of the injection system to
obtain the appropriate operating permit(s). State and Federal
UIC rules require strict compliance to provide maximum assurance
that underground sources of drinking water (defined as, among
other criteria, aquifers containing 10,000 mg/L or less total
dissolved solids) will not be negatively impacted by underground
injection of domestic wastewater.
A useful reference to assist with well design criteria
is Ground Water and Wells, UOP Inc., 1975.
9.3.2.4
Operational Considerations. There are several
operational considerations when designing an injection well.
One possible concern with injection wells may be clogging of the
aquifer around the well, especially at the borehole interface
between the gravel pack (if used) and the borehole wall.
Suspended solids can accumulate and bacterial growth tends to
concentrate in this area. Other processes that can decrease
injection rates in wells are precipitation of calcium carbonate,
iron oxides, and other compounds in the aquifer; dispersion and
swelling of clay; and air binding.
Injection wells are more vulnerable to clogging than
surface infiltration because the infiltration rates are much
higher. Clogging effects can be remediated by several methods,
including periodic pumping of the wells to reverse the flow and
potentially dislodge clogging materials, or acidization of the
injection well. When the wells are pumped, the initial flow is
typically brown and odorous and is recycled through the treatment
plant. Pumping schedules may range from 20 minutes per day to
several times per year. If pumping does not restore the
injection rate, redevelopment of the well may be necessary. The
best strategy for dealing with clogging is to prevent it by
proper treatment of the water before injection. Limiting the
loading of suspended solids, assimilable organic carbon,
nutrients such as nitrogen and phosphorus, and microorganisms may
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