MIL-HDBK-1005/16
Anchoring is often accomplished by burying the pipeline and using
a 90-degree elbow at the end to surface the outfall. Multiport
outfalls may have risers along the pipeline extending above the
buried pipeline. Piers can be used to support the outfall for
some of the distance from shore, but the pipeline extending
beyond the pier (to avoid public contact) needs anchoring.
Sometimes pipes have collar-type concrete weights that can be
partially submerged with jets to anchor the pipeline. Sometimes
rip-rap is used to stabilize and provide ballast for the pipeline
sitting on the bottom grade. Abovegrade pipelines can experience
sedimentation and scour forces which need to be considered by the
designer.
Address COE requirements and state ownership of the
water body during design. If the pipeline is too shallow, it can
interfere with boat traffic. Some regulatory agencies will allow
a shallow outfall if it is marked with lighted warning buoys or
by other means. The transition zones near the shoreline will
need special consideration during design and construction, since
these are often the most environmentally sensitive and publicly
visible areas.
9.3
Groundwater Recharge. Groundwater recharge can be
accomplished by the use of infiltration basins or through
underground injection wells.
9.3.1
Infiltration Basins. Artificial recharge of
groundwater can be achieved with infiltration basins if soils are
permeable, a sufficient portion of the aquifer is unsaturated,
and the aquifer is unconfined.
9.3.1.1
Applications Guidance. Design and management of
infiltration basins should be adapted to local conditions of
water quality, climate, soil, hydrogeology, and environmental
constraints. Aspects to be considered include water depth (in
reference to possible increase in infiltration rates), length of
flooding and drying periods, frequency of cleaning basins, and
pre-sedimentation. Also, a selection between basins with
stagnant water (where fine materials are able to settle) or
basins with flowing water (where fine materials are kept
suspended because of turbulence) should be made. Chemical and
biological water quality parameters of the effluent water need to
be considered. Also consider changes in water quality as the
water moves through the vadose zone and aquifer, and potential
leaching of trace elements from the vadose zone. A groundwater
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