1. II. Sewer Network and Facilities Topic II. 10
II. Sewer Network and Facilities Topic 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

2. 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

3. Schemes of Drop Manholes Structures
Kinds of Drop Manholes
Schemes of Drop Manholes Structures
a - 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

4. Shaft type without stilling pool and for low drops
Kinds of Drop Manholes
Shaft type without stilling pool and for low drops

5. Kinds of Drop Manholes Shaft type with horizontal baffles (scheme)
Kinds of Drop Manholes Shaft type with horizontal baffles (scheme) Chute type with stilling pool

6. Drop Manhole with a Baffle and Stilling pool
Kinds of Drop Manholes
Drop Manhole with a Baffle and Stilling pool

7. 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

8. Inverted Siphons I. Purpose II. Main Parts
For overcoming terrain obstacles by the sewer - with
pressure pipes
For overcoming underground obstacles by the sewer - with
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

9. Inverted Siphons
Principal Scheme

10. Inverted Siphon (Scheme of Main Parts)

11. Inverted Siphon