2019-08-29_PERMIT FILE - M2019028 ‎(3)‎

• Permit No: M2019028
• IBM Index Class Name: PERMIT FILE
• Doc Date: 8/29/2019
• Doc Name: Adequacy Review Response
• From: J&T Consulting
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

Technical Review Guidelines for Gravel Mining&Water Storage Activities
When the length of the riverside berm is greater than 1,300 feet, two spillways shall be
constructed and the bottom length of each spillway shall conform to the following relationship:
Ls = 0.6 Ap/12,000
or
Ls = 100 feet,whichever is greater.
In which:
Ls = length of the side channel spillway
Ap = area of pit measured in square feet at the high water line
Protection with the grouted boulder rundown on the pit side slope may be used to stabilize the
spillways. Construction of this type of spillway stabilization must conform to the requirements
indicated in Figure 2.8. The riverbank should be stabilized in accordance with the requirements of
Section 2.3—Riverbank Protection. The crest of the spillway will be vegetated and shall have a
10-foot-wide stabilized maintenance access trail along the entire crest of the spillway. The
objective is to provide a smooth, flat driving surface with the ramps between top of berm and
spillway bottom being no steeper than 10 percent. Access ramps, if sloped different than the side
slopes of the spillway, shall not protrude into the bottom width of the spillway. The pitside
rundown slope will be protected using grouted boulders. Grout used for the grouted boulder
portion of this structure and installation practices shall be per the USDCM Hydraulic Structures
chapter.
Concrete may be used to protect spillways through riverside banks. The design of the concrete
shall include consideration of all forces which may be encountered including, but not limited to,
uplift forces and pore pressures generated by underlying materials. The riverbanks shall be
protected in accordance with the requirements of Section 2.3—Riverbank Protection. Whenever
concrete lining is used for the spillways, the geometric configuration of the concrete used to
protect the spillway should conform to the dimensions shown on Figure 2.9.
Soil cement is also an acceptable form of protection for side channel spillways. The riverbanks
should be protected in accordance with the requirements of Section 2.3—Riverbank Protection.
The crest of the riverside berm will be protected with a layer of soil riprap. The layer of soil
cement on the spillway crest must be a minimum of 2 feet thick. The pitside slope is to be
protected with soil cement placed in horizontal layers not exceeding 8 inches in thickness and
between 8 and 12 feet wide. The soil cement should conform to the requirements of Section
2.4.3—Soil Cement. The geometric configuration of soil cement for stabilizing side channel
spillways should conform to the dimensions shown on Figure 2.10.
January 2013 Urban Drainage and Flood Control District Page 18