Page 454 - Water and wastewater engineering

GRANULAR FILTRATION 11-27

Wash troughs
Intel main

Graded
filter
Wash water sand
outlet

Graded gravel
Perforated pipe
Outlet main
laterals
(a)
Gravel
placed
on top
of
block

(b)
IMS® cap Grout Sand

FIGURE 11-10
Filter underdrains: ( a ) perforated pipe laterals,
Concrete
( b ) vitrified clay block, (c) Integral Media Support
R
(IMS ). In view ( c ): left is water flow during filtra-
(c) tion, right is backwash flow pattern.