2013-10-30_REVISION - M1977310 ‎(3)‎

• Permit No: M1977310
• IBM Index Class Name: REVISION
• Doc Date: 10/30/2013
• Doc Name: DRAINAGE DESIGN PLAN FOR THE JD6 MINE
• From: COTTER
• To: DRMS
• Type & Sequence: AM1
• Email Name: TC1
• Email Name: SJM
• Media Type: D
• Archive: No

JD-6 Mine – Drainage Design Plan 47
Attachment 1. Rip Rap Granular Bedding Specifications (from UDFCD 2011)
DRAINAGE CRITERIA MANUAL (V 1) MAJOR DRAINAGE
Table MD -1 I-- Gradation for Granular Bedding
U.S. Standard Sieve Size
Percent Weight by Pass Square-Mesh Sieves
Type I COOT Sect 703 01
Type it CDOT SW,
703,09 Class A
3 inches
9t3 100
inches
inches
—
20-90
- - - --------- - 1/i, Inches
100
#4
95-100
0-20
#16
45-80
—
#50
10.30
#100
2.10
—
#200
0_2
0-3
The Type I and Type 11 bedding specifications shown In Table MD -11 were developed using the T-V filter
criteria and the fact that bedding which will protect an underlying non - cohesive soil with a mean grain size
of 0,046 mm Will protect anything finer. Since the T-V filter criterion provides some latitude in establishing
bedding gradations, it is possible to make the Type I and Type 11 bedding specifications conform with
Colorado Division of Highways' aggregate specifications The Type I bedding in Table MD-11 is designed
to be the lower layer in a two-layer filter for protecting fine-grained soils and has a gradation identical to
Colorado Department of Transportation's (CDO'rs) concrete send specification AASHTO M-6 (CDOT
Section 703,01), Type 11 bedding, the upper layer in a two-layer fitter, is equivalent to Colorado Division
of Highways' Class A filter material (Section 703.09 Class A) except that it permits a slightly larger
maximum rock fraction When the channal is excavated in coarse sand and gravel (50% or more of
coarse sand and gravel retained on the #40 sieve by weight), only the Type 11 filter Is required
Otherwise. a two-layer bedding (Type I topped by Type 11) is required. Alternatively, a single 12-inch layer
of Type 11 bedding can be used, except at drop structures. For required bedding thickness, see Table
MD -12. At drop structures, a combination of fitter fabric and Type 11 bedding is acceptable as an
alternative to a two-layer fitter,
Table MD-12—Thickness Requirements for Granular Bedding
Minimum Bedding Thickness (inches)
Riprap Designation Fine-Grained Soils" Coarse-Gr;ihSoilT
Type I Type 11 Type Ii
VL ( dw = 6 in), L Pao = 9 in) 4 4 6
M (dw = 12 in) 4 4 6
H (d5o = 18 in) 4 6 8
VH (car = 24 in) 4 6
May substitute one 12-inch layer of Type 11 bedding. The substitution of one layer of Type 11 bedding shall not
be permitted at drop structures The use of a combination of filter fabric and Type 11 bedding at drop structures
is acceptable.
Fifty percent or crone by weight retained on the # 40 sieve.
Rev 0412008
Urban Drainage and Rood Cont'ol Dotict
MD-87
4148A.131028 Whetstone Associates 6