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TNTAKE FACILITIES 4.7

Vacuum line

J,
High water

: ,'~
!1~ ~'- Siphon chamber
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54-in.-diameter caisson

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,I Vacuum High water
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kow water

FIGURE 4.4 Siphon well intakes.

The groundwater potential of a river valley is also worthy of consideration. Gravel-
packed wells or horizontal groundwater collection systems (collector wells) may, on oc-
casion, offer an economical alternative to difficult, costly intake construction and the as-
sociated operating challenges when geologic conditions are favorable. Well intakes are
not subject to the river intake hazards of navigation; flood damage; clogging with fish,
sand, gravel, silt, ice, or debris; and extreme low water. An additional benefit associated
with well intakes is the improved water quality due to riverbank filtration resulting from
the surface water being subjected to ground passage prior to its collection. The water ob-
tained from well intake systems along rivers is typically a mixture of groundwater and
induced flow from the river. Gravel-packed wells are vertical collection systems with typ-