2018-09-04_PERMIT FILE - C1981019 ‎(3)‎

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 9/4/2018
• Section_Exhibit Name: Exhibit 07 Item 15 Haul Road A Upper and Lower Ditches
• Media Type: D
• Archive: No

Exhibit 7, Item 15
Haul Road A
Upper and Lower Ditch Design
This section addresses the design of the Upper and Lower Ditches at the toe of the deeper fills
along Haul Road A above Taylor Creek. The constructed toe of the fills from the Haul Road A
widening occurred directly into a native channel, and to ensure long-term stability of the fills two
ditches will be constructed to route surface water flows at the toe of the fill down the natural
drainage.
Designs for both of these ditches are based on the 10 year, 24-hour storm event. Methodologies
and assumptions for both ditches are derived from Volume 21) Exhibit 7. Curve numbers for some
native areas subwatersheds in this hydrology demonstration were increased as the curve number
for native areas (Volume 2D Exhibit 7) created an error in SEDCAD due to zero flow.
Contributing watersheds and subwatersheds for both ditches are shown on Figure Exh. 7-15-1.
Both ditches will be riprap lined as specified in the SEDCAD model.
Locations, contributing watersheds, and profiles of the Upper and Lower Ditches are shown on
Figure Exh. 7-15-1. The dimensions, lining type, and flow characteristics for all ditches are
included in the SEDCAD attached output. However, the design and actual minimum construction
specifications are summarized on the below table.
Exh. 7, Item 15, Page 1 Revision Date: 6/15/18
Revision No.: TR -122
Average
Side
Minimum
Design
Slope
Lining
Specified
Bottom
Slope,
Rip Rap,
Ditch Name
Event
Flow Q
%
Type
Depth
Width
HAV
DSO n
UpperDitch
10 r 24 hr
3.5
11.0
Riprap
2.0
4.0
2:1
3.0
Lower Ditch
10 yr 24 hr
8.97
6.7
Riprap
2.0
4.0
2:1
3.0
Exh. 7, Item 15, Page 1 Revision Date: 6/15/18
Revision No.: TR -122