UFC 3-280-04
17 DEC 2003
Table 5-3. Typical Media Designs
Characteristics
Values
Range
Typical
Dual Media
Anthracite
Depth, mm
300600
450
Effective size, mm
0.82.0
1.2
Uniformity coefficient
1.31.8
1.6
Sand
Depth, mm
150300
300
Effective size, mm
0.40.8
0.55
Uniformity coefficient
1.21.6
1.5
TriMedia
Anthracite
Depth, mm
200500
400
Effective size, mm
1.02.0
1.4
Uniformity coefficient
1.41.8
1.6
Sand
Depth, mm
200400
250
Effective size, mm
0.40.8
0.5
Uniformity coefficient
1.31.8
1.6
Garnet or ilmenite
Depth, mm
50150
100
Effective size, mm
0.20.6
0.3
Uniformity coefficient
1.51.8
1.6
Source: WEF (1992)
Table 5-4. Typical Media Designs
Media
Anthracite Coal
Silica Sand
Garnet
Typical
Design
Application
Conditions
Effective
Depth
Uniform-
Effective
Depth
Uniformity
Effective
Depth
Uniformity
Size
(mm)
ity
Size
(mm)
Coeffi-
Size
(mm)
Coefficient
(mm)
Coeffi-
(mm)
cient
(mm)
cient
Single
--
--
--
12
1525
1.2
--
--
--
A
Single
--
--
--
23
1830
1.11
--
--
--
A
Dual
0.9
915
<1.6
0.35
305
<1.85
--
--
--
B
Dual
1.84
380
<1.1
0.55
380
<1.1
--
--
--
A
Tri
1.0
430
1.61.8
0.42
230
1.31.5
0.21
100
1.51.8
B
1.1
0.48
0.23
Tri
1.2
760
--
0.80.9
305
--
0.40.8
150
--
C
1.3
Note: A = heavy loading, strong floc.
B = moderate loading, weaker floc.
C = moderate loading, strong floc.
Source: EPA 570/9-91-004
5-1.2.9 Media Support and Underdrain Systems. With the exception of upflow and
downflow continuous backwash systems, granular filtration media are supported by an
underdrain system. In addition to providing this support, the underdrain system acts to
distribute the backwash water evenly, collect the filtered water, and prevent loss of the
5-10
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