Powerline Plan and Environ. Assessment Jan. 2013 - Flood Control ...

Powerline Flood Retarding Structure Draft Supplemental Watershed Plan
Pinal County, AZ
and Environmental Assessment
NRCS Table 3b - Structural Data – Channel Work, Powerline FRS Apache Junction-Gilbert Watershed, Maricopa and Pinal Counties, AZ
Channel Dimensions
n-Value
Velocities
(ft/s)
Channel
Name
(Reach)
Station
Drain
Area
(mi 2 )
100 Year
Freq Design
Discharge
(ft 3 /s)
Water
Surface
Elevation
Feet
(msl)
Hydraulic
Gradient
(ft/ft)
Gradient
(ft/ft)
Bottom
Width
(ft)
Elevation
(ft/msl)
Side
Slope
Aged
As-
Built
Aged
As-
Built
Excavation
Volume
(yd 3 )
Type
of
Work
1/
Existing
Channel
Type 2/
Present
Flow
Condition
3/
CP25
10+00 to
27+50 2.1 984
1602.0
1597.1 0.0017 0.0017 60
1598.0
1595.1 6 0.045 - 2.9 - 13,900 I O E
CP25
Hardened
27+50 to
46+50 2.1 939
1597.1
1593.8 0.0017 0.0017 60
1595.1
1591.8 2 0.013 - 7.0 - 13,800 I O E
CP9
46+50 to
61+50 12.5 3,153
1593.8
1594.1 0.0017 0.0017 150
1591.8
1589.2 6 0.045 - 3.4 - 30,600 I O E
CP5R
Hardened
61+50 to
77+50 21.5 7,746
CP5R
77+50 to
Vineyard
Road Flood
Pool 21.5 8,129
CP4
(Siphon
Draw) 25.2 13,444
1/
2/
3/
I-Establishment of new channel including necessary stabilization measures
II-Enlargement or realignment of existing channel or stream
1594.1
1590.7 0.0017 0.0017 150
1590.7
1580.4 0.0017 0.0017 500
1599.0
1579.1 0.0037 0.0037 1000
III-Cleaning out natural or manmade channel (including bar removal and major clearing and snagging operations)
IV-Clearing and removal of loose debris within channel section
V-Stabilization as primary purpose (by continuous treatment or localized problem areas-present capacity adequate)
N-An unmodified, well-defined natural channel or stream
M-Manmade ditch or previously modified channel or stream (show approximate date of original construction in parenthesis)
O-None or practically no defined channel
Pr: Perennial - Flows at all times except during extreme drought
I: Intermittent - Continuous flow through some seasons of the year
E: Ephemeral - Flows only during periods of surface runoff, otherwise dry
S: Ponded water with no noticeable flow-caused by lack of outlet or high groundwater table
1589.2
1586.5 2 0.013 - 11.0 - 48,700 I O E
1586.5
1576.0 6 0.045 - 3.3 - 911,900 I O E
1595.9
1576.0 6 0.045 - 4.1 - 455,500 I O E
January 2013
USDA- NRCS Page 8-11 January 2013
Kimley-Horn and Associates, Inc.