MIL-HDBK-1005/16
monitoring program may be required based on Federal or state
regulations and depending on the quality of the effluent
discharged to the basins. Proximity of public drinking water
wells may also affect the groundwater monitoring requirements.
Refer to Artificial Recharge of Groundwater, A.I. Johnson and
Donald J. Finlayson, eds., 1988.
9.3.1.2
General Design Guidance. Infiltration systems for
artificial recharge of groundwater should consist of a number of
basins, in cases where hydraulic loading rates need to be
maximized. Depending on topography, such basins can have a
surface area of 0.25 to 25 acres (0.10 to 10 hectares) or more.
Each basin requires its own water supply and drainage so that it
can be flooded, dried, and cleaned according to the best schedule
for that basin. Basins should not be placed in series so that
the outflow from one basin is the inflow for the lower basin
because in such systems the basins cannot be dried and cleaned
individually. Design the overall system to allow any basin to be
taken out of service for a sufficient drying period. The first
few basins are sometimes designed to be used as pre-sedimentation
basins. Some basins, particularly deep or low infiltration
basins, should be designed with separate drainage systems, which
allow quick de-watering for drying and cleaning. Construct
basins with horizontal or well-graded bottoms to prevent low
places where water can stand for long periods and interfere with
infiltration recovery and cleaning operations.
In cases where groundwater mounds could rise above the
bottom of the infiltration facilities, the basins should be laid
out to minimize the inundated area. Groundwater flow modeling,
using readily available models such as MODFLOW, may be required
to evaluate potential mounding effects during the design. The
basins should be small or long and narrow. Adjacent basins
should not be flooded at the same time. Refer to EPA 625/1-81-
013a, Process Design Manual for Land Treatment of Municipal
Wastewater, Supplement on Rapid Infiltration and Overland Flow.
9.3.2
Injection Wells. Many successful injection well
systems, which inject moderately to highly treated wastewater,
have been constructed across the United States. Many of these
systems are located in California, Texas, and Florida. Injection
wells are characterized under five general categories (Class I,
II, III, IV, or V) based on the type of waste stream, well
design, use of well, and hydrogeologic characteristics at the
injection site. Florida's injection well classifications, which
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