II. Sewer Network and Facilities Topic II. 10. Drop Manholes: Kinds and Structures. Inverted Siphons

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II. Sewer Network and FacilitiesTopic II. 10.
Drop Manholes Kinds and Structures.Inverted
Siphons

• Purpose
• For overcoming terrain obstacles by the sewer
• For overcoming underground obstacles by the sewer
• For sewers at steep terrain
• For sewer branches joining deeper collectors
• For buildings sewer joining deep street
  collectors
• For sewer outlets under the receiving water level

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Kinds of Drop Manholes

• I. According to the drop height
• With low drop height (h lt 6 m)
• With high drop height (h gt 6 m)
• II. According to the flow energy dissipation
• Shaft type (with or without stilling pool and/or
  baffles)
• Chute type (with stilling pool)
• With bar racks (without stilling pool)
• With baffles (with or without stilling pool)
• With flow split and mutual energy dissipation

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Kinds of Drop Manholes

• Schemes of Drop Manholes Structures
• a - chute type without stilling pool ? - chute
  type with stilling pool b - with baffle and
  stilling
• pool ? - shaft type without stilling pool ? -
  shaft type with stilling pool e - shaft type
  with
• declined baffles ? - shaft type with horizontal
  baffles

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Kinds of Drop Manholes

• Shaft type without stilling pool and for low drops

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Kinds of Drop ManholesShaft type with horizontal
baffles (scheme) Chute type with stilling pool
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Kinds of Drop Manholes

• Drop Manhole with a Baffle and Stilling pool

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Kinds of Drop ManholesShaft Type Drop Manhole
for High Drops

• 1 - open channel to the
• stilling pool
• 2 - vertical shaft pipe
• 3 - inlet sewer pipe
• 4 - manhole
• 5 - installation opening
• 6 - cover plate
• 7 - stairs
• 8 - intermediate stage
• 9 - cunette platform

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Inverted Siphons

• I. Purpose
• For overcoming terrain obstacles by the sewer -
  with
• pressure pipes
• For overcoming underground obstacles by the sewer
  - with
• pressure pipes
• II. Main Parts
• Inlet chamber (with sluice gates or stop valves)
• Outlet chamber (without sluice gates or stop
  valves)
• Pressure pipes
• For dry weather flow
• For wet weather flow
• Emergency bypass pipe

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Inverted Siphons

• Principal Scheme

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Inverted Siphon (Scheme of Main Parts)
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Inverted Siphon