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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 < 6 m) With high drop height (h > 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 Structuresa - chute type without stilling pool; б - chute type with stilling pool; b - with baffle and stilling

pool; г - shaft type without stilling pool; д - shaft type with stilling pool; e - shaft type with

declined baffles; ж - 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 Manholes

Shaft 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