CIVIL ENGINEERING FORMULAS

364 CHAPTER THIRTEEN

wherellength of weir, ft
hdepth of flow over weir at down-stream end, ft

Siphon spillways are better adapted to handling large storm water and sewer
flows. The area for the siphon throat, A sq ft, is:

(13.10)

whereQdischarge, ft^3 /s
ccoefficient of discharge, which varies from 0.6 to 0.8
gacceleration due to gravity 32.2 ft/s^2
hhead, ft

DESIGN OF A COMPLETE-MIX
ACTIVATED SLUDGE REACTOR

The volume of the reactor can be determined using the following equation
derived from Monod kinetics:

Vr (13.11)

(^) cQY(SoS)
Xa(1kd (^) c)

A

Q

c 2 gh

Combined

sewer

Siphon

Bypass

Combined

sewer

Storm

sewer Sewer

Air vent

Weir

(a) (b)

Wet-weather

flow

(c)

Sanitary

sewer

Storm

sewer

FIGURE 13.2 Flow-regulating devices for sewers: (a) Side weir. (b) Siphon spillway.

(c) Leaping weir. (Merritt—Standard Handbook for Civil Engineering, McGraw-Hill.)