final summary report drainage system evalutation … of mesa drainage system evaluation - phase ii...

ATION PHASE I1

pa County, Arizona

Concentration Point 109A - combined Quarter Section Map Numbers 107B,D,108A,B,C,D,109A,116A,B,D

Outfall ID MH-624 ,

Drainage Area 0.14 sq miles Areas with 100% Retention 1.75 sq miles

Total Area 1.89 sq miles

Step 1: Determine Weighted dunoff Coefficient (C)

Description of Land Use Runoff Coefficient (C)

Total 90.8 acres 87.6 acres (reduced)". Weighted Runoff Coefficient* =

Step 2: Determine Time of Concentration (T,)

L = Length of the Longest Flow Path in feet ........................... 13,210 feet ............................... K b = Watershed Resistance Coefficient*" 0.050

S = Watercourse Slope in feettmile ...................................... 79.2 Wmile

Iterative Process to Determine Tc and Rainfall Intensity (I)

Step 3: Calculate Peak Discharge ('Q)

Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.80 ................... I

= Rainfall Intensity in incheslhour (1 0-yr storm). 2.1 0 inlhr = Rainfall intensity in incheslhour (100-yr storm) ................... 3.24 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 87.6 acres ........................................... Q z o = 10-yr Peak Discharge in cfs 147 cfs .......................................... Qloo = 100-yr Peak Discharge in cfs 227 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residentlal areas to account for retention occurfng

within walled back yards. Thk reduced drainage area is used when calculating the weighted runoff coefflcIent,

as well as the peak discharge. **For the purposes of this study, the watershed resistance coefficient is constant for all drainage areas.

NAGE SYSTEM NALUATION - PHASE I! Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 117D Quarter Section Map Numbers

Outfall ID Drainage Area 0.15 sq miles

Areas with 100% Retention 0.1 I sq miles Total Area 0.26 sq miles ,

Step 1: Determine Weighted Runoff Coefficient (C)


Total 97.4 acres 90.1 acres (reduced)" Weighted Runoff Coefficient* = IZZ8

Stew 2: Determine Time of Concentration (7,)

........................... L = Length of the Longest Flow Path in feet 8,930 feet s"

............................... K b = Watershed Resistance Coefficient** 0.050 ...................................... S = Watercourse Slope in feetlmile 79.2 ft/mile

Iterative Process to Determine T, and Rainfall lntensity (I)

- - I - -

Tc - -

Q = CIA

......................................... Runoff Coefficient (weighted).

Rainfall intensity in incheslhour (10-yr storm) .................... Rainfall Intensity in incheslhour (IOO-yr storm) ...................

.............. Drainage Area* (contributing areas only) in acres., ........................................... IO-yr Peak Discharge in cfs

........................................ 100-yr Peak Discharge in cfs..

0.78

2.60 inlhr

3.91 inlhr

90.1 acres 183 cfs

275 cfs

* The drainage area is reduced by 25% of the medium densify and medium to low density residential areas to account for retention occuring

within walled back yards. This reduced drainage area is used when calculating the weighted runoff coemcient,

as well as the peak discharge. **For the purposes of this study, the watershed resistance coefncient is constant for all drainage areas.

CIN OF MESA DRAINAGE SYSTEM EVALUATION - PHASE II Rational Method Calculation Sheet Source: Drainage Design Manual for aricopa County, Arizona

Concentration Point Quarter Section Map Numbers

Outfall ID Drainage Area

Areas with 100% Retention Total Area

0.23 sq miles 0.77 sq miles 1 .OO sq miles


Description of Land Use I Runoff Coefficient (C) I Residential - low densi

Total 145.7 acres

126.30 acres (reduced)* Weighted Runoff Coefficient* =

S t e ~ 2: Determine Time of Concentration (T,)

L. = Length of the Longest Flow Path in feet ........................... 10,560 feet ............................... K ~ J = Watershed Resistance Coefficient** 0.050

S = Watercourse Slope in feetlmile ...................................... 79.2 ft/mile

Iterative Process to Determine Tc and Rainfall Intensity (1)

- - I - -

TC - -

Step 3: Calculate Peak Discharge (Q)

Q = CIA

C = Runoff Coefficient (weighted). .................................... 0.63 .................... I = Rainfall Intensity in incheslhour (10-yr storm) 2.40 inlhr

= Rainfall Intensity in incheslhour (100-yr storm) ...............,... 3.53 inlhr

A = Drainage Area* (contributing areas only) in acres ..............,. 126.3 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 191 cfs ......................... ......... Qioo = 100-yr Peak Discharge in cfs ... 281 cfs

* The drainage area is reduced by 25% of the medium dens@ and medium to low density residential areas to account for retention occuring within wailed back yanls. This reduced drainage area is used when calculating the weighted runoff coefficient,

as well as the peak discharge. HFor the purposes of this study, the watershed resisfance coeti7clent is constant for all drainage areas.

CITY OF MESA DRAINAGE SYSTEM Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1208 Quarter Section Map Numbers 120A, B, C, D

Outfall ID MH-313C-S Drainage Area 0.02 sq miles

Areas with 100% Retention 0.98 sq miles Total Area I .OO sq miles

Step I: Determine Weighted Runoff Coefficient (C)

Runoff Coefficient

I .

Total 15.8 acres

NA acres (reduced)* Weighted Runoff Coefficient* = 1283,

Step 2: Determine Time of Concentration (7,) P

Tc = 1f,4 ~ 0 . 5 ~ ~ " 5 2 ~ " 3 1 i-0.38

L = Length of the Longest Flow Path in feet ................... :. ...... 5,280 feet ............................... K b = Watershed Resistance Coefficient** 0.050

...................................... S = Watercourse Slope in feet/mile 49.1 Nmile

Iterative Process to Determine 7, and Rainfall lntensity (I)

- I

- - -

Tc - -

Step 3: Calculate Peak Discharge (9)

Q = CIA

........................................ C = .Runoff Coefficient (weighted).. 0.83 ................... I = Rainfall Intensity in incheslhour (1 0-yr storm). 2.75 inlhr

= Rainfall Intensity in incheslhour ( I 00-yr storm). .................. 4.1 9 inihr

A = Drainage Area* (contributing areas only) in acres ................ 15.8 acres ........................................... QIO = 10-yr Peak Discharge in cfs 36 cfs

Q ~ o o = 100-yr Peak Discharge in cfs ..,......................................t 55 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas fo account for retention occuring

within walled back yards. This reduced drainage area Is used when calculating the weighted runoff coefficient,

as well as the peak discharge.

*For the purposes of this study, the watershed resistance coefficient is consfant for all drainage areas.

Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfall ID HWl24B-S Drainage Area 0.26 sq miles

Areas with 100% Retention 0.73 sq miles Total Area 0.99 sq miles


Description of Land Use Runoff Coefficient (C) I

Total 163.7 acres

161.73 acres (reduced)* Weighted Runoff Coefficient* = Qsi!

Step 2: Determine Time of Concentration (7,)

I. = Length of the Longest Flow Path in feet ........................... 7,275 feet

............................... K b = Watershed Resistance Coefficient*" 0.050 S = Watercourse Slope in feetlmile ...................................... 79.2 Wrnile

Iterative Process to Determine 7, and Rainfall Intensity (I)

Step 3: Calculate Peak Discharge (Qj

Q = CIA

Runoff Coefficient (weighted). ......................................... Rainfall Intensity in incheslhour ( I O-yr storm) .................... Rainfall Intensity in incheslhour (1 00-yr storm) ................... Drainage Area* (contributing areas only) in acres ................

........................................ 10-yr Peak Discharge in cfs...

........................................ 100-yr Peak Discharge in cfs..

0.59 2.75 inlhr

4.14 in/hr

161.7 acres 262 cfs

394 cfs

* The drainage area is reduced by 25% of the medium density and medium fo kw density residential areas to account for refentlon occuring wa in walled back yards. This reduced drainage area is used when calculating the weighted runoff coefnclent,

as well as the peak discharge. **For the purposes of this study, the watershed resistance coefncient is constant for all drainage areas. .

INAGE SYSTEM EVALUATION - PHASE II Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfall ID Drainage Area


126B 126A, B, C, D HWI 19C-N

0.24 sq miles 0.76 sq miles 1 .OO sq miles

Step I: Determine Weighted Runoff CoefTicient (C)


Total 155.6 acres

124.58 acres (reduced)* Weighted Runoff Coefficient* = !LZQ

Step 2: Determine Time of Concentration (T,) L

L = Length of the Longest Flow Path in feet ........................... 10,560 feet

............................... Kb = Watershed Resistance Coefficient** 0.050 ...................................... S = Watercourse Slope in feetimile 79.2 Wmile



Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.70 ................... 1 = Rainfall Intensity in incheslhour (10-yr storm). 2.40 inlhr

= Rainfall Intensity in incheslhour (100-yr storm) ............,...... 3.53 inlhr

................ A = Drainage Area* (contributing areas only) in acres 124.6 acres ..................... ................... Qlo = 10-yr Peak Discharge in cfs .., 20

.......................................... QIOO = 100-yr Peak Discharge in cfs 306 cfs

* The drainage area is reduced by 25% of the medium densify and medium to low densify residential areas to account for retention occuring within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient,


INAGE SYSTEM NALUATIO Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1278 Quarter Section Map Numbers 1276,127D

Outfall ID MH-513 Drainage Area 0.01 sq miles




Total 8.4 acres

NA acres (reducedy Weighted Runoff Coefficient* = Qa.@


Tc = 77.4 ~ 0 ~ 5 ~ ~ 0 . 6 2 ~ 4 . 3 f j.0.38


............................... K b = Watershed Resistance Coefficient*" 0.050 ...................................... S = Watercourse Slope in feetlmile 49.1 ft/mile

Iterative Process to Determine T, and' Rainfall lntensity (I)


Q = CIA

C = Runoff Coefficient (weighted) ......................................... 0.83 ........... ........

I = Rainfall Intensity in incheslhour (10-yr storm) ; 3.60 inlhr .................. = Rainfall Intensity in inches/hour (1 00-yr storm). 5.28 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 8.4 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 25 cfs ......................................... Qzoo = 100-yr Peak Discharge in cfs 37 cfs

* 7he drainage area Is reduced by 25% of the medium density and medium to low densify residential areas to account for retention occuring

within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient,

as well as the peak discharge. e

**For the purposes of this study, the watershed resistance coeMcIent is constant for all ddnage areas.

ll'Y OF MESA DRAINAGE SYSTEM EVALUATION a PHAS ational Method Calculation Sheet

Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1318 Quarter Section Map Numbers 131 B

Outfall ID HW-125C-S Drainage Area 0.01 sq miles




Total 4.8 acres NA acres (reducedy Weighted Runoff Coefficient* =

Step 2: Determine Time of Concentration fl,) i

L = Length of the Longest Flow Path in feet ........................... 1,800 feet ............................... K b = Watershed Resistance Coefficiente* 0.050

S = Watercourse Slope in feetlmile ...................................... 79.2 Nmile

Iterative Process to Determine T, and Rainfall intensity (I)

I = l~ainfall Intensity (100-yr) in incheslhour OM i-D-F curve) 1 6.50 1 6.75 1 6.78 1 I I I 1


Q = CIA

C = Runoff Coefficient (weighted) ......................................... 0.83 ....................

i = Rainfall Intensity in inches/hour (10-yr storm) 4.37 inlhr ................... = Rainfall intensity in incheslhou~ (100-yr storm) 6.39 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 4.8 acres .......................................... Qlo = 10-yr Peak Discharge in cfs. 17 cfs .......................................... Qioo = 100-yr Peak Discharge in cfs 25 cfs

* me drainage area is reduced by 25% of fhe medium density and medium to low densify residential areas to account for retention occuring

within walled back yanls. This reduced drainage area is used when calculating the weighted runoff coefficient,

as well as the peak dischar?ge. **For the purposes of this study, the watershed resistance coeMcient is constant for all drainage areas.

C I N OF MESA DRAINAGE SYSTEM LUATION - PHASE II Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfail ID HWl25C-N Drainage Area 0.79 sq miles

Areas with 100% Retention 0.21 sq miles Total Area 1 .OO sq miles



Total 505.3 acres

NA acres (reduced)* Weighted Runoff Coefficient* =


L = Length of the Longest Flow Path in feet ........................... 10,560 feet ............................... K b = Watershed Resistance Coefficiente* 0.050

S = Watercourse Slope in feetimile ...................................... 79.2 ft/mile

Iterative Process to Determine T, and Rainfall Intensity (I)

Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.58 .................... I

= Rainfall Intensity in incheslhour (10-yr storm) 2.40 inkr

= Rainfall Intensity in incheslhour (100-yr storm) ................... 3.53 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 505.3 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 701 cfs .......................................... QIOO = 100-yr Peak Discharge in cfs 1,032 cfs

* 730 dralnage area Is reduced by 25% of the medium density and medlum fo [ow density residential areas to account for retention occuring

within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficIenf,

as well as the peak dlscharge. *For the purposes of thls study, the watershed resistance coefficient is constant for all drainage areas.



Ouffall ID NA Drainage Area 0.22 sq miles


Step 1: Determine Weighted Runoff Coefficient (6)


Total 137.8 acres 107.8 acres (reduced)* Weighted Runoff Coefficient* = - 0.63


........................... L = Length of the Longest Flow Path in feet 3,500 feet

Kb = Watershed Resistance Coefficient*" ............................... 0.050


Iterative Process to Determine Tc and Rainfall lntensity (I)


Q = CIA

C = Runoff Coefficient (weighted). .......................... ;. ............. 0.63

................... I = Rainfall Intensity in incheslhour (10-yr storm). 3.62 inlhr

= . Rainfall Intensity in incheslhour (100-yr storm) ................... 5.37 inlhr

A = Drainage Area* (contributing areas only) in acres... .........,.,. 107.8 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 2

Qioo = 100-yr Peak Discharge in cfs .......................................... 367 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retention accuring within walled back yank This reduced drainage area is used when calculating the weighted nrnoff coefficient,

as well as the peak discharge. "For the purposes of tftis study, the watershed resistance coefficient is constant for all drainage areas.

CITY OF MESA DRAINAGE SYSTEM EVALUATION - PHASE II Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 133A - combined Quarter Section Map Numbers 133A, 132A,B,C, &D, 131 0

Outfall ID HW-I 25C-S Drainage Area 1.01 sq miles




Total 649..1 acres

61 9.1 acres (reduced)" Weighted Runoff Coefficient* =


L = Length of the Longest Flow Path in feet ........................... 11,780 feet ............................... K b = Watershed Resistance Coefficient** 0.050

S = Watercourse Slope in feetlmile ...................................... 79.2 Wmile

Iterative Process to Determine 7, and Rainfall Intensity (I)

- - I - -

Tc - -


Q = CIA

C = Runoff Coefficient (weighted).. ....................................... 0.59 .................... I = Rainfall Intensity in incheslhour (10-yr storm) 2.30 inlhr

= Rainfall Intensity in incheshour (100-yr storm) ................... 3.34 inhr

A = Drainage Area* (contributing areas only) in acres ................ 619.1 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 833 cfs .......................................... Qloo = 100-yr Peak Discharge in cfs 1,210 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retention occuring

within wailed back yards. This reduced drainage area is used when calculafing the weighfed runoff coefficient,


**For the purposes of this study, the watershed msistance coefficient is constant for all drainage areas.

INAGE SYSTEM EVALUATION - PHASE II Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfall ID Drainage Area 0.01 sq miles

Areas with 100% Retention 0.40 sq miies Total Area 0.41 sq miles



Total 7.8. NA

acres acres (reduced)? Weighted Runoff Coefficient* = QJXi


Tc = 11.4 L 0.6 Kb 0.52 S-0.37 i4.38


............................... K b = Watershed Resistance Coefficient** 0.050 S = Watercourse Slope in feetfmile ...................................... 79.2 Wmile


- - I - .n.

Tc - -


Q = CIA

C = Runoff Coefficient (weighted).. ..................................... 0.83 ................... I = Rainfall Intensity in incheslhour (1 0-yr storm). 4.00 inlhr ................... = Rainfall Intensity in incheslhour (100-yr storm) 6.03 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 7.8 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 26 cfs ........................................ Q i o o = 100-yr Peak Discharge in cfs 39 cfs

* The drainage area is reduced by 25% of the medium densfly and medium to low density residential areas to account for retention occuring

within walled back yards. 7111s reduced drainage area is used when calculatlng the weighted runoff coefficient,

as well as the peak dischame. **For the purposes of this study, the watershed resistance coefficient is constant for aN drainage areas.

INAGE SYSTEM EVALUATION - PHASE II ational Method Calculation Sheet


Concentration Point 134D Quarter Section Map Numbers 134C, 134D

Outfall ID HW 1 34D-S Drainage Area 0.01 sq miles

Areas with 100% Retention 0.20 sq miles L

Total Area 0.21 sq miles



Total 9.0 acres



L = Length of the Longest Flow Path in feet ........................... 3,000 feet ............................... Kb = Watershed Resistance Coefficient** 0.050


Iterative Process to Determine T, and Rainfall Intensity (I)

Q = CIA

C = RunoffCoefficient(weighted) .......................................... 0.83

.................... I = Rainfall Intensity in incheslhour (10-yr storm) 3.85 idhr = Rainfall Intensity in inches/hour (1 00-yr storm).. ................. 5.65 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 9.0 acres ......................................... Qlo = I 0-yr Peak Discharge in cfs.. 29 d s

.......................................... Qioo = 100-yr Peak Discharge in cfs 42 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density resldential areas to account for retention occuring within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient,


INAGE SYSTEM NALUATI Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1358 Quarter Section Map Numbers 135B, 135D

Outfall ID MH-1270-N Drainage Area 0.02 sq miles



I J

Total 15.8 acres

NA acres (reducedy Weighted Runoff Coefficient* = a83,

Ster, 2: Determine Time of Concentration ff,)

L = Length of the Longest,Flow Path in feet ........................... 5,280 feet

............................... Kb = Watershed Resistance Coefficiente* 0.050

S = Watercourse Slope in feeffmile ..................................... 49.1 Wmile



Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.83 .................... I = Rainfall Intensity in incheslhour (10-yr storm) 2.75 inlhr ................... = Rainfall Intensity in incheslhour (100-yr storm) 4.19 idhr

A = Drainage Area* (contributing areas only) in acres ................ 15.8 acres .......................................... Q f o = 10-yr Peak Discharge in ds 36 cfs

..................... ................ Q ~ o o = 100-yr Peak Discharge in cfs .... 55 cfs

* The drainage area is reduced by 25% of fhe medium densily and medium to low density resldenUa1 areas to account for retention occuring

Wthin walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient,

-& as well as the peak discharge.

HFor the purposes of this study, the watekhed resistance coefncfenf is constant for all drainage areas.

NAGE SYSTEM EVALUATION - PWAS Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1398 Quarter Section Map Numbers 139B, 139D

Outfall ID HW-1248-S Drainage Area 0.01 sq miles



Total 4.2 acres

NA . acres (reduced)* Weighted Runoff Coefficient* = QAU

S t e ~ 2: Determine Time of Concentration (7,)


............................... Kb = Watershed Resistance Coefficient*" 0.050 ...................................... S = Watercourse Slope in feevmile 79.2 ft/mile



Q = CIA

.......................................... C = Runoff Coefficient (weighted) 0.83 .................... I = Rainfall Intensity in incheslhour ( I 0-yr storm) 4.50 inlhr

.................. = Rainfall Intensity in incheslhour ( I 00-yr storm). 6.95 inihr

A = Drainage Area* (contributing areas only) in acres ................ 4.2 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 16 cfs ......................................... QIOO = 100-yr Peak Discharge in cfs. 24 cfs

* 7716 drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retention occuring


as well as the peak discharge. T o r the purposes of this sfudy, the watershed resistance coefficient is constant for aN drainage areas.

C I N OF MESA DRAINAGE SYSTEM EVALUATION - PHASE I1 Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfail ID HW124B-S Drainage Area 0.29 sq miles



area #. (acres) I Sub- I Area I Description of Land Use Runoff Coefficient (C)

Total 186.1 acres

NA acres (reduced)* Weighted Runoff Coefficient* = QAB



K b = Watershed Resistance Coefficiente*.. ;. ..... 0.050 ...................... ...................................... S = Watercourse Slope in feetlmiie 79.2 ftlmile


- I

.,.r

- - T c - -


Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.66

.................... I = Rainfall Intensity in incheslhour (10-yr storm) 2.40 inlhr

= Rainfall Intensity in incheslhour (1 00-yr storm) ................... 3.53 inlhr

A = Drainage Area* (contributing areas only) in acres... ............. 186.1 acres

Qzo = 10-yr Peak Discharge in cfs ........................................... 296 cfs

......................................... QIOO = 100-yr Peak Discharge in cfs. 436 cfs

* The drainage area is reduced by 25% of the medium densify and medium to low density residential areas to account for retention occuring

wlfhin wakd back yards. 7his reduced drainage area is used when calculating the weighted runoff coefficient,

as well as the peak discharge. i - **For the purposes of thls sfudy, the watershed resistance coefficient Is constant for all drainage areas.

c l n OF MESA DRAINAGE SYSTEM EVALUATION - PHAS Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 141A Quarter Section Map Numbers 141A

Outfall ID NA Drainage Area 0.23 sq miles



t I I I


Total 150.0 acres 120.0 acres (reduced)* Weighted Runoff Coefficient* =

Sten 2: Determine Time of Concentration (T,)

L = Length of the Longest,Flow Path in feet ........................... 3,500 feet ............................... K b = Watershed Resistance Coefficiente* 0.050

S = Watercourse Slope in feetlmile .................................... 79.2 Wmile



Q = CIA

C = Runoff Coefficient (weighted). ......................................... 0.65 ................. I = Rainfall Intensity in incheslhour (10-yr storm).,. 3.62 inlhr

= Rainfall Intensity in incheslhour (100-yr storm) ................... 5.37 inlhr .............. A = Drainage Area* (contributing areas only) in acres.. 120.0 acres

Q.ro = 10-yr Peak Discharge in cfs ........................................... 283 cfs

QIOO = 100-yr Peak Discharge in cfs .......................................... 420 cfs

* m e drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retention occuring within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient,

as well as the peak discharge. **For the purposes of thls study, the watershed resistance coefficient is constant for all drainage areas,

UATION - PHASE II

copa County, Arizona


Outfall ID Drainage Area '


141A - combined 141A, 140A, B, C, & D, 1398 & D MH-4546

0.53 sq miles 1.04 sq miles 1.57 sq miles


area # I Sub- (acres) Area I Description of Land Use Runoff Coefficient (C)

Total 340.3 acres

31 0.3 acres (reduced)" Weighted Runoff Coefficient* = QvkY2

Sten 2: Determine Time of Concentration f f , 1

T, = 11.4 ~ 0 . 5 ~ ~ 0 . 5 2 ~ 5 . 3 1 i5.38


...................................... S = Watercourse Slope in feetimile 79.2 ft/miie



Q = CIA

C = Runoff Coefficient (weighted). ....................................... 0.65 .................... I = Rainfall Intensity in inchesthour (10-yr storm) 2.12 inlhr

= Rainfall Intensity in incheslhour (1 00-yr storm). .................. 3.09 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 310.3 acres Qlo = 10-yr Peak Discharge in cfs ......................... ., ............... 428 cfs

QIOO = 100-yr Peak Discharge in cfs .......................................... 623 cfs

* me drainage area is reduced by 25% of the medium density and medium to low densify residential areas to account for retention occuring

within walled back yards. This reduced drainage area is used when calculaffng the welghfed runoff coemcient,

as well as the peak discharge. HFor the purposes of this sfudy, the watershed resisfance coefficient is constant for all drainage areas.



Outfail ID ,

Drainage Area Areas with 100% Retention

Total Area

1410 14lD

HW-141 D-W 0.30 sq miles 0.00 sq miles 0.30 sq miles



Total 194.0 acres

154.0 acres (reduced)* Weighted Runoff Coefficient* =


T, = 77.4 ~ 0 . 5 ~ ~ 0 . 5 2 ~ 4 . 3 1 i4.38


............................... K b = Watershed Resistance Coefficient*" 0.050

S = Watercourse Slope in feetlmile ...................................... 79.2 ftlmile


- I

- - -

Tc - -


Q = CIA

C = Runoff Coefficient (weighted) ......................................... 0.65 .................... I = Rainfall Intensity in inchesthour (10-yr storm) 3.1 5 inlhr

= Rainfall Intensity in inchesthour (100-yr storm) ................... 4.71 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 154.0 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 314 cfs

.......................................... Qtoo = 100-yr Peak Discharge in cfs 469 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residenfial areas to account for retention occuring


as well as the peak discharge. **For the purposes of this study, the wafershed resistance coefficient is constant for all drainage areas.

INAGE SYSTEM EVALUATION - PHAS Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 1428 Quarter Section Map Numbers 142B

Outfall ID , HW-134B-S Drainage Area 0.07 sq miles




Total 45.8 acres .

NA acres (reduced)?: : Weighted Runoff Coefficient* =.



S = Watercourse Slope in feetJmile ...................................... 79.2 Wmile

Iterative Proces ; to Determine Tc and Rainfall Intensity (I)


Q = CIA

C = Runoff Coefficient (weighted) .......................................... 0.65

................... I = Rainfall Intensity in incheslhour ( I O-yr storm). 4.00 inlhr

= Rainfall Intensity in incheslhour (IOO-yr storm) ................... 6.03 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 45.8 acres ........................................... Q ~ o = 10-yr Peak Discharge in cfs 11 ......................................... Qioo = 100-yr Peak Discharge in cfs 179 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for refentlon occurfng within walled back yards. This reduced drainage area is used when calculating the weighted runoff coefficient, as well as the peak discharge. T o r the purposes of this study, the watershed resistance coefhcient is constant for all drainage areas.

INAGE SYSTEM EVALUATION PHASE It Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona


Outfall ID Drainage Area sq miles

Areas with 100% Retention sq miles Total Area sq miles



15.8 acres Total NA acres (reduced)* Weighted Runoff Coefficient* = aL8;2,

Step 2: Determine Tina of Concentration (T,)

L = Length of the Longest Flow Path in feet ......................... :. 5,280 feet ............................... K b = Watershed Resistance Coefficient** 0.050

S = Watercourse Slope in feetlmile. ....................... , ........... 49.1 Wmile


- I

- - -

Tc - -


Q = CIA

C = Runoff Coefficient (weighted) ........................................ 0.83 .................... i = Rainfall Intensity in incheslhour (10-yr storm) 2.75 inlhr

= Rainfall Intensity in incheslhour ( I OO-yr storm) ................... 4.19 inlhr

A = Drainage Area* (contributing areas only) in acres. ............... 15.8 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 36 cfs

Q i o o = 100-yr Peak Discharge in cfs .......................................... 55 cfs

* The drainage area is reduced by 25% of the medium densify and medium to low densify residential areas to account for retention occurlng



EVALUATION - PHASE ll

Maricopa County, Arizona

Concentration Point 3128 - combined Quarter Section Map Numbers 312A,B,C,D, 313A,B,C,D, 314A,B,C,D

Ouffall ID MH-313B-S Drainage Area 0.1 1 sq miles



72.5 acres Total NA acres (reduced)? Weighted Runoff Coefficient* = QLa

tep 2: Determine Time of Concentration (T,)

T, = 11,4 ~ 0 . 5 ~ ~ 0 . 5 2 ~ - 0 . 3 1 i-0.38


............................... K b = Watershed ~esistance Coefficient** 0.050 S = Watercourse Slope in feetlmile ...................................... 49.1 Wmile

Iterative Process to Determine T, and Rainfall Intensity ( I f .

Step 3: Calcuiate Peak Discharge (Q)

Q = CIA

C = Runoff Coefficient (weighted) ....................................... 0.83

.................... I = Rainfall Intensity in incheslhour (10-yr storm) 1.83 inlhr


............. A = Drainage Area* (contributing areas only) in acres... 72.5 acres .......................................... Qlo = 10-yr Peak Discharge in cfs. 110 cfs

.......................................... Qioo = 100-yr Peak Discharge in cfs 162 cfs

* The dralnage area is reduced by 25% of the medium density and medium to low denslty residential areas to account for refenffon occuring

wifhin walled back yards. This reduced drainage area is used when calculating the welghted runoff coefficient,

as well as the peak discharge. *For the purposes of this study, fhe watershed resistance coefficient is constant for aN drainage areas.

INAGE SYSTEM EVALUATION * PHAS Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 31 38 Quarter Section Map Numbers 313A, B, C, D

Outfall ID MH-3136-S Drainage Area 0.05 sq miles


Step 1: Determine Weighted Runoff Coefficient (6)


TotaZ 31.6 acres

NA acres (reducedy Weighted Runoff Coefficient* = !uB Sten 2: Determine Time of Concentration lT, 1


K b = Watershed Resistance Coefficient** ......,.... ;. 0.050 .................. ...................................... S = Watercourse Slope in feeffmile 49.1 Wmiie

Iterative Proces s to Determine Tc and Rainfall lntensity (I)


Q = CIA

C = Runoff Coefficient (weighted) ..................................... 0.83

................... I = Rainfall Intensity in incheslhour ( I 0-yr storm). 2.75 inlhr = Rainfall Intensity in incheslhour ( I 00-yr storm).,. ................ 4.19 inlhr

A = Drainage Area* (contributing areas only) in acres. ............... 31.6 acres ........................................... Qlo = 10-yr Peak Discharge in cfs 72 cfs

Qioo = 400-yr Peak Discharge in cfs .......................................... 110 cfs

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retenflon occuring

within walled back yards. This reduced drainage area is used when calculafing the weighted runoff coemcient,

as well as the peak discharge. **For the purposes of this study, the watershed resisfance coemcient is constant for all drainage areas.

INAGE SYSTEM EVALUATIO Rational Method Calculation Sheet Source: Drainage Design Manual for Maricopa County, Arizona

Concentration Point 314B Quarter Section Map Numbers 314A, B, C, D

Outfall ID MH-313C-S Drainage Area 0.05 sq miles



Runoff Coefficient

Total 31.6 acres



T, = 11.4 ~ 0 . 5 ~ ~ 0 . 5 2 ~5.3' i-0.38

........................... 1 = Length of the Longest Flow Path in feet 5,280 feet ............................... K b = Watershed Resistance Coefficiente* 0.050

...................................... S = Watercourse Slope in feetlmile 49.1 ft/mile



Q = CIA

C = Runoff Coefficient (weighted). ......................................... 0.83

.................... I = Rainfall Intensity in incheslhour ( I O-yr storm) 2.75 in/hr = Rainfall Intensity in incheslhour (I OO-yr storm) ................... 4.19 inlhr

A = Drainage Area* (contributing areas only) in acres ................ 31.6 acres ........................................... Qio = 10-yr Peak Discharge in cfs 72 cfs

QIQO = 100-yr Peak Discharge in cfs .......................................... 110 cfs 1

* The drainage area is reduced by 25% of the medium density and medium to low density residential areas to account for retention occudng

wifhin walled back yards. This reduced drainage area is used when calculating fhe weighted runoff coefncient,



Concentration Point 317B - combined Quarter Section Map Numbers 143B, D, 144, B, C, D & 317A, B, C, D

Outfail ID Mti-317B-S Drainage Area 0.07 sq miles


Step 1: Determine Weighted Runoff Coefficient (C) i

area Sub # I (acres) Area I Description of Land Use Runoff Coefficient (C)

Total 47.4 acres .

NA acres (reduced)* Weighted Runoff Coefficient* = QJE!




I = l~ainfall Intensity (100-yr) in incheslhour (from I-5-F curve) 1 2.90 1 2.70 1 2.66 1 1


Q = CIA

C = Runoff Coefficient (weighted). ......................................... 0.83 .................... I = Rainfall Intensity in inchesihour (10-yr storm) 1.69 inlhr


A = Drainage Area* (contributing areas only) in acres ................ 47.4 acres .......................................... (210 = 10-yr Peak Discharge in cfs. 66 cfs

....................................... (2100 = 100-yr Peak Discharge in cfs... 99 cfs

* The drainage area is reduced by 25% of fhe medium density and medium to low density resldenfial areas to account for retention occuring

within walled back yards. This reduced drainage area Is used when calculaflng the weighted runoff coemcient,


*"For the purposes of this study, fhe watershed &stance coefficient is constant for all drainage ateas.

Page I

. 96" , 448 552 1 850 , 935 , 944 952 ' 965

rnannings roughness coefficient = 0.013 I I I

9f 17199 PROPOSED STORM D IN DIAMETER AT OUTFALL Page 1

1184.20 1194.20 1 4000 0.0025 1 W I Tempe Storm Sewer Road to Main Street

1000.00 100250 1000 0.0025 60 Main Street at the Tempe Canal

,94.24 1207.44 5280 0.0025 54 University Drive: Dobson Road to Alma School Road

1194.56 1 1202.56 1 3200 1 0.0025 1 48 1 Baseline: Alma School Road to Extension

1212.61 1 1215.91 1 1320 1 0.00'25 1 42 1 Road: Main Street

121223 1215.53 1320 0.0025 30 Alma School Road: Railroad track to Broadway Road

1000.00 1031.75 12700 0.0025 84 Lehi: Center to Gilbert

1207.68 1 121268 1 2000 I 0.0025 1 48 1 Bmadway Road to 2nd Street

10oo~OO 1 1003.50 1 ,400 1 0.0025 1 36 1 Mesa Drive: Lehi to Future Red Mountain Freeway

Mesa Drive: Bates Road to McKellips i I I

36 Mesa Drive: Tempe Canal to McKeilips

1229.24 1 1230.49 1 500 1 0.0025 1 24 1 Mesa Drive: Ternpecanalto Brown Road

1229.24 1 1234.24 1 2000 / 0.0025 1 30 1 Mesa Drive: 8th Streetto Brown Road I I

1232.77 1239.37 2640 0.0025 36 Mesa Drive 8th Street to University

1217.47 1222.47 2000 0.0025 48 Mesa Drive: 2nd Street to Broadway

1000.00 I 1005.00 I 2000 I 0.0025 1 42 1 Stlpley Red FreMy lehi Road

1251.96 1 1253.96 1 800 1 0.0025 1 24 1 Stapley Southern Canal to McKellips

1 1251.96 1 1265.16 1 5280 1 0.0025 1 36 1 Stapley Brown Roadta McKellips

3 1230.70 1240.95 4100 0.0025 36 * University: Consolidated Canal to Staple]

*a-llO'R.O.W. "c-Q10 TI-130'R.0.W. *d-a100 "e - MIST. OUTFALL CAPACITY * - ASSUMED ADEQUATE CAPACITY

911 7199 PROPOSED STORM D IN DIAMETER AT OUTFALL Page 2

Stapley Drive: Main Street to Broadway

Broadway: Harris to Stapley

Gilbert Road: Brown to McKellips

Brown: Lindsay to Giibert

University: Lindsay to a p p m 25th Street

Broadway Road: Consolidated Canal to Gilbert Road

University: Eastern Canal to Lindsay

Lindsay: 8th Street to University

Main Street Val Vista to Lindsay

Southern: Consolidated Canal to Lindsay

Southern: Consolidated Canal to 32nd Street

Lindsay: US 60 to Baseline

Val Vista: Southern Canal to McKellips

Val Vista: Brown Road to Adobe

Greenfield Road: Red Mountain Freeway to McDoweli

University: RWCD Canal to Greenfield Road

Broadway Road: RWCD Canal to Greenfield Road

Higley Road: McLellan to Brown Road

Higley Road: Brown Road to Adobe

McDoweli Road: Power Road to Recker

Recke~ McKellips to 114 mile north of Brown Road

Power Road: Future Red Mountain Freeway to McDowell

McDowell Road: Salt-Gila Aqueduct to Power Road

Power Road: McDowell to McKellips

Power Road: McKellips to Brown Road

Power Road: Brown Road to Adobe

Lhiversity: Hawes to Sossaman

Sossaman: University to Apache Boulevard

Broadway Road: Crisrnon to Ellsworth

"a-110' R.O.W. 'c-Q10 "b-130'R.0.W. *d-Q100 *e - EXIS. OUTFALL CAPACITY * - ASSUMED ADEQUATE CAPACITY

University. Crismon to Salt-Gila Aqueduct

Ellsworth: U S 60 to Baseline Road

University: Meridia

Elriot Ellsworth to RWCD Canal

Hawes: Guadalupe to Elliot

i

\ *a-llO'R.O.W. % - G I 0 a - 130. R.O.W. -d - a l o o f - EXIST. OUTFALL CAPAC17Y * - ASSUMED ADEQUATE CAPACTPI

Location: Concentration Point: 5B-Corn bined

TOTAL COST $1,418,229

'Unit Cost lncludes Factor for Utility Relocation

Location: Concentration Point: 005C Outfall ID: MH4150

*Unit Cost Includes Factor for Utility Relocation

Location: 8th Avenue at the Tempe Canal

Concentration Point: 006C

Outfall ID:

*Unit Cost includes Factor for Utility Relocation

Location: University Drive - Dobson Road to Alma School Road

Concentration Point: 01 28 Outfall ID: MH3893

*Unit Cost Includes Factor for Utility Relocation

final summary report drainage system evalutation … of mesa drainage system evaluation - phase ii...

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