OFFICE MEMORANDUM

>~ ~

MICHIGAN

DEPARTMENT OF STATE HIGHWAYS

G. J. Fellows Engineer of Design

From, Max N. Clyde Engineer of Design

December 14, 1967

Subject, Storm Sewer Design Program

In accordance with your conversation with J. V. Murray, we are transmitting the originals of the Storm Sewer Design Program. Please pre­pare and distribute copies of the program to the interested and affected parties to insure uniformity in storm sewer design throughout the Department.

Upon completion, please return the originals to the Utility Design Section.

MAX N. CLYDE

JEngine~ of Design

r/'1/. )1~ . V. MURRAY

Design Supervising Engineer

DD/AJI/gp

STORM SEWER DESIGN

Following is the procedure to be used in the design of storm

sewer systems for highway drainage. This procedure incorporates

several changes in Department policy on sewer design.

changes are:

The major

1. All storm sewers will be designed on a full flowing

basis.

2. Storm sewer design for depressed freeways, using a 50

year storm frequency, will be based upon the sewer flowing under

a head with the hydraulic gradient being a minimum of 1 foot below

gutter grade. A further restriction on the use of this method

provides that the sewer must have an independent outlet.

3. Sewers will be designed with a limiting maximum velocity

of 10 fps with a normal maximum of 8 fps. In extreme cases,

velocities in excess of 10 fps may be tolerated, however; the

designer should obtain the approval of the Utility Design Section

before using higher velocities.

1

1. General

The MDSH uses the rational method for the design of all storm

sewers. The rational method translates rainfall into runoff by

the formula Q = CIA in which:

a. Q is the maximum rate of runoff expressed in cubic feet

per second (CFS),

b ~ "C" is a runoff coefficient which is an estimate of the

ratio of the maximum rate of runoff to the average rate of rainfall

on the area during the time of concentration.

c. "I" is the average rainfall intensity, in inches per

hour, for the period of maximum rainfall having a duration equal

to the time of concentration.

d. A is the drainage area, in acres, tributary to the

point under design.

2. Runoff Coefficient "C"

As the rational method uses average rainfall intensities

prevailing over the time of concentration, which bear no relation

to storm pattern, the use of average "C" values has proven an

acceptable tool in sewer design.

The Department considers the runoff coefficient to be largely

dependent on the percentage of imperviousness of the area under

consideration. Figure 1 indicates the "C" factors to be used for

varying degrees of imperviousness from 1% to 100%.

Following is a list of suggested "C" values for the types

of surface commonly found in the design of highway drainage

systems.

2

Type of Surface % Impervious "C" Value

Pavement and Bituminous Shoulder 100 0.80

1 on 2 Slopes 70 0.60

Flat Unpaved Areas-Heavy Soils 30 0.28

Flat Unpaved Areas-Sandy Soils 10 0.10

Residential Areas 30-60 . 3 to . 5

Commercial Areas 60-100 . 5 to . 8

It is often desirable to develop a weighted "C" factor for

an area with several types of surface. Following is an example

demonstrating this technique as applied to a typical highway cross

section.

ROW Width

Pavement

Sidewalks

Flat Grassed Area (Clay Soil)

100Ft.

60 Ft.

12 Ft.

28 Ft.

60 X .8 = 48.0

12 X • 8 9 • 6

28 X .28 7.8

65.4 -!- 100 .65 weighted "C" value

3. Rainfall

a. Frequency

All highway storm sewers are to be designed for storms

having a 10 year frequency except that a 50 year frequency

storm shall be used at underpasses or other depressed road­

ways on the interstate system, and trunklines built to

3

a. Frequency cont.

interstate standards, where ponded water can only be removed

through the storm drain system.

b. Intensity Duration Curves

The rainfall intensity duration curves in Figures 2

through 5 are from U.S. Weather Bureau Technical Paper No. 25.

The localities to which these curves apply are shown in

Figure 6. Table 1 is developed from these curves and gives

the rainfall intensity directly for times between 10 minutes

and 4 hours for the four zones and return periods of 10 and

50 years.

c~ Time of Concentration

The time required for the maximum rate of runoff to

develop is known as the time of concentration. Generally,

it is the time required for a drop of water to flow from the

most remote part of the drainage area to the point under

design. It consists of two parts; the initial or inlet

time and the time of flow in the sewer.

The time of flow in the sewer can be closely estimated from

the hydraulic properties of the sewer. Average flowing-full

velocities expected at the prevailing sewer slope or the slope of

the hydraulic grade line are to be used.

The initial or inlet time must be estimated by the designer.

Past experience has indicated a 15 minute initial time to be

adequate for the design of most highway sewers. However, the

steep grades associated with single sag depressions tend to

produce more rapid runoff. If construction of a pumphouse is

contemplated, at such a location the use of a 10 minute initial

time is warranted. Where multiple sags drain to a common pumphouse

4

a 15 minute initial time is again adequate.

Some circumstances, as when an open drainage system is to

outlet into a proposed storm sewer, may require special study to

determine the initial time.

4. Drainage Area

The area tributary to any point under consideration in a

storm sewer system must be determined. It can be measured

accurately and is the only element of the rational formula

subject to precise determination.

The Department's storm sewers are normally designed to

accommodate the runoff from highway right of way only. However,

in keeping with the Department's "Drainage Policy and Guide,"

allowances should be made to accommodate the surface drainage of

those areas outside the right of way, which slope naturally

towards the roadway, in the condition of imperviousness in effect

at the time of design.

5. Velocities

Generally, design velocities should satisfy the following

conditions:

Min.

Desirable Min.

Max.

Desirable Max.

Velocity

Velocity

Velocity

Velocity

3 fps

4 fps

10 fps

8 fps

When the design is based on a hydraulic grade line the

physical grade of the sewer does not determine the design velocity.

5

Care should be exercised therefore, to assure that the physical

grade of the sewer is such as to provide reasonable self cleaning

velocities atflows less than the design storm.

The following table lists the minimum construction grades to

be used for various sizes of circular concrete pipe storm sewers.

Pipe Size Grade % Pipe Size Grade %

12 0.48 54 0.09

15 0.36 60 0.09

18 0. 2 8 66 0.08

21 0.22 72 0.08

24 0.17 78 0.08

27 0.16 84 0.07

30 0.15 90 0.07

33 0.14 96 0.07

36 0.12 102 0.06

42 0.12 108 0.06

48 0.10 120 0.06

6. Storm Sewer Design Procedure

?allowing is an outline of a typical procedure for the design

of a storm sewer:

1. Obtain prints showing the proposed highway construction.

2. Locate the manhole and inlets on the plan portion of the

prints. (See Sections 5.148 and 5.152 of the Highway Survey and

Design Manual for typical structure spacing)

3. Number the above structures.

4. Determine the area draining to each manhole or inlet and

compute its weighted "C" value.

6

5. Enter the above information on the tabulation sheet.

6. Sketch the desired sewer grade or hydraulic gradient on

the profile sheet and calculate its approximate slope.

7. Obtain the rainfall intensity from Table 1 for the

appropriate initial time.

8. Compute the runoff (Q) for the uppermost structure by

multiplying the weighted "C" factor x intensity x area (CIA).

9. Enter the nomograph in either Figure 7 or 8 with the

above Q and select a sewer size that will accommodate this flow

when flowing full at a grade approximating the slope of the

hydraulic gradeline.

10. Determine the velocity of flow from the nomograph

interpolating between tbe lines of equal velocity as required.

11. Compute the flow time in the sewer from the first to

the second manhole. Add this value to the initial time to obtain

the time of concentration for the second manhole.

12. Add the acreage draining to the second structure to that

of the first and determine the weighted "C" value for the

accumulated area.

13. Compute the estimated runoff at the second structure

using the accumulated area, its weighted "C" factor and the

rainfall intensity corresponding to the new time of concentration.

14. Select a pipe size as in 9 above.

15. Repeat steps 10 through 14 to determine sewer sizes at

the suceeding structures.

Upon completion of the above design adjustments of the H.G.L.

and sewer sizes may be required to obtain the most economical

system consistant with good sewer design practices.

7

7. Estimating Runoff

On occasion the designer may be required to make a preliminary

estimate of the storm water runoff to be discharged to an existing

sewer or to be pumped from a depressed section.

The following procedure is suggested:

1. Assume an average sewer velocity of 5 fps or 300 feet

per minute.

2. Estimate the time of concentration:

Initial Time + L 300

Where L is the length of the approach sewer. (Note:

Where two approach sewers are involved use the longer sewer to

estimate the time of concentration).

3. Determine the total drainage area and its weighted "C"

value.

4. Obtain the rainfall intensity from Table 1 for the

estimated time of concentration.

5. Multiply the total drainage area by the weighted "C"

value and the rainfall intensity to obtain the estimated runoff.

8

FIGURE I

MICHI~AN DEPARTMENT or STATE HI GHWAVS 0 A T A e E N T E R

TABLE OP RUNOFf COEI"I"'eiENTS CTO BE USED WITH 5EWER DESIGN PROGRAM 0401'!0)

PCT RUNDf"f peT RlJNOf"f" PCT RuNorr IMPERV COEFF C IMPERV COEFF C !MPERV cour e

1 • 0.0!3'5 41. 0' 37'50 13 I , (),61'7'2 2. 0,0233 42, 0,3833 82, 0,6840 3, 0,0330 43. 0,3915 83, 0,6908 4, Oo0427 411. (),3997 84, (),691''5 5, 0,0523 45, 0,4079 85, (),'1'(1112 6, 0.0619 46, 0,4160 86, 0,1'108 .,, o.o/'15 47. 0.4241 87, (), 7'174 a, 0,01'110 48. 0,4321 88, 0,1'?40 9, 0,0905 49, 0,4402 89, 0,7305

10. 0,1000 so. 0,4461 90, 0,131'0

11. 0.1094 '51. 0,4561 91. 0,'1'435 !2, 0.1188 52, 0,4640 92, 0,'1'1199 13' 0,1282 53. 0.47'19 93, o,7'163 111. 0.137'5 '54, 0,41'97' 911, (),1',,_., 15o 0,1468 55, 0,481'5 95, o,7690 16, Ool560 56, 0,4953 96, Oo11'53 17, 0,1652 57. 0.5030 97, 0.1'1115 18. 0,17'44 58, 0,5107 98, o, 7'1lH 19, 0' lE135 59. 0.5183 99, (),1'939 20, 0' 1926 60, 0,5259 100, o,aooo

21. 0,2016 61' 0,5335 22, 0.2107 112, 0,'5410 23, 0.2196 113, 0,5465 24, Oo2286 1\4, 0,5560 25, 0.2375 1\5, 0,5634 26, 0.2464 66, 0,5708 2'1', 0,2552 117, 0.51'8:?. 28, 0.2640 68, (),5855 29, Oo21'28 1\9, 0.5928 30, 0,21115 '1'0, 0,6000

31. 0,2902 7! ' 0,601'2 32. 0.2988 '1'2. Oo<H44 33, 0,307/i 73, 0.6215 34, 0,3160 74, Oo6286 35, 0,324') 75, 0,6356 36, 0,3330 76, 0,6427 3'/', 0,341"1 17, 0.6496 31!, (),31!99 '1'8, 0' 6566 39, 0,3563 7'9, (),6635 40. (),366'1' f\Q, o,6T04

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TABLE 1

'0!CHIGA'I flEPARTMf"NT OF <;TATE HIGHWAYS

RA TNF"ALL I~ITENS! iY 9 D!IRATION TARLF <TD BE USEfl WITH SEWFR DESIGN PROGRAt-A ll40Afl)

T!ME 70'1( 70NE ;> ZONE ~ 70NE 4 TN

M!NIITES )0 9 VR so~vR !O~VR 'iO~vR tn~vR sn~vR )r'lwYR 50 9 YR

)('),() s . :n 7,08 l!.'ifl '5,98 3,78 /j. 9 8 ~.91'> '5,;>3 1 (J .1 5,2'5 7,05 4,54 'i,CJS 3,7(> 1!,9'5 3.94 "·21 )('),2 '5,22 7,02 4,5! '5,93 3,74 4, CJ:l 3,93 '!.19 111 • ~ 5,20 6,99 4,4C) 5,90 3.72 /j' 9 0 3,91 'l' 1 6 )(1,4 5, l A 6,97 4,47 5,1\7 3,70 4,1'\A 3,89 5. 1 4 Hl, 5 ~ & 1" 6,94 4,4'\ '5,85 3,68 lj,l'\'5 3,R7 'i.)2

111,6 5. 14 1\,91 4' 4 1 5,R2 3,61\ 4,A'l 3,811 5.10 10,7 5' 1 2 6,88 4 '4 1. 'i.Ro 3,65 4 • ill 3,84 'i,07 1fl.11 s • 1 () 6,86 4,411 '5,77 3,63 4,7f', 3,8::> o;,os 1(),9 5.08 6.1'13 4,3R S,?'i 3' 6 j 4,7f, 3, R 1 ';,03 11 '0 5,06 6,80 4,31'> '1,7;> 3,59 4,74 3,7<1 5,01

11.1 5,04 6,78 4,34 5,70 3,58 4' 71 3,7R 4,99 11 '2 5,02 6,75 4,1::> 'S,Ail 3,56 4,<'>9 3,7A 1!. 9 7 11 ,3 5,Q() 6,73 4 ' l f1 "i,A5 3.54 4 ' 1\7 3,74 4,95 1 1 ' 4 4,98 6,70 4,;>R 5,<'>3 3' 53 4,65 3' 7 ~ 4,93 1 1 ' 'i 4,9fl 6,68 411~7' "\,61 3.51 lj • "'3 3' 7 1 4,91

11 '6 4,94 6,65 4,;>'i 'i,S8 3,49 /j' "'0 3,711 11, R 9 1 1 ' 7 4,'12 6,63 4,;:>1 '5,'i6 3.48 4,';8 3,6R 4,87 1 I , 11 4,90 6,61 4 ' ::> 1 5,54 3,46 4,'\A 3,67 4,115 1 I , 9 4 .tlA 6,58 ,,;>n '5,'52 3.4'i 4,'i4 :!,65 4,f',3 1?.0 II, A 7 6,56 4, 1 R '5,119 3,43 llo'52 3,1\4 4, A 1

12.1 4,85 6,53 4. 1"' 'i,47 3,42 i.l,'i() 3 'I'>' 4,79 1?. 2 4,83 6,51 4 • \ 'i '5,45 3.40 4,4B 3 '6 1 4,77 1 ;>. 3 4,81 6,49 4' 1' '\,43 3.3'1 4,41\ 3,6(1 4,76 1?.4 4,79 6,47 4' 1? "io41 3.3 7 4' 4 4 3,5!'\ 4,74 12.5 4,7/l 6.44 4.1(} "i,39 3,36 4.4? 3 '57 4,72

1:>,1> 4.76 6,42 4,0'1 5 ' 'l 7 3,34 /j' 4 0 3,56 4,70 \?,7 4.74 6,40 4.01' '5,15 3, :n 4' 3 8 3,54 4,69 1?,8 4. 73 11,38 4,0'\ 5, ''13 3.31 I!' 'H 3 ''i i 4,67 12,9 4,71 6' 3 6 4,04 'i,1j 3,30 4. ::15 3 ''i? 4,65

1 '' 0 4.69 6,34 4.0? 5,;>9 3.29 IJ,j:l 3.50 /j '6 3

1 '.1 4,6fl 6,31 4,01 '5,?7 3,27 /j ' 3 1 3,4'l 4.62 1 3'? 4,6<'> 6,29 3,90 '3,;>5 3,?6 4,;>9 3,41'1 lj '6 0 l 1' 3 4,65 6,27 3,9A '5,?3 3.25 4,;:>7 3.46 4,58 1 3. 4 4,63 6,25 3,91'. "·'1 3.23 4,?6 3.4'1 4.57 13o'i 4,61 6.23 3,9'i 5' 1 9 3.22 /j' 2 4 3' 411 4,'i5

13,1'> 4,60 1\,21 3.9~ 5' 1 7 3.2! 4,;>:;> 3' 4 1 4,53 jj,7 4,')8 I) ' 1 9 3,9? "i,j6 3.!9 II , ? 1 3,4::> 4,52 1 'I ' 8 4.57 6.17 3,90 5.!4 3,jll 4' 1 9 J,4fl 4,50 13.9 4,55 1:>,[5 3,8'l 5.12 3.17 4,)7 3,39 /j' 4 9

Tl>.1E INTERVAL ON THIS SHEET = () • 1 MINUTE 17

TABLE 2

~I CHI GMI !'IFPART~FNT OF STATF HIGHWAYS

RAINFALL I~tTENSTTY - f111RATION TARLF (Til RE USEf1 w ITY SEWER nESTGN PROGRAM "4f1f\())

T T "'E 70'IF 1 7DNF ;> ZONE i 70NE 4 TN

MlNIITES 1n-vR 50-YR lr1-YR 'iO-YR 1n-vR 5n-yR !!1-VR 50-YR

14,() 4,54 6.13 3,8R "i' 1 0 3' 16 ll • 1 5 ),311 11 , 4 7

1 4 ' 1 4,5? 6. 11 J,Rt, 5,()8 3. 14 11 • 1 4 3.37 4,46 1 4. 2 4,51 1>,09 3,8'i '5,()7 3.13 It o\2 3,1A 4,44 1 4 • 3 4' 4 9 6,08 J,R4 "i,os 3' 11' II , 1 1 3,1b 4.42 1 4. 4 4,4FI i),Q() 3,8? <;,113 3' 11 /j' 09 3, :n 4' 4 1 liJ,'i 4,4A A,04 3 ' ill '5,01 3,09 /j '() 7 3,3? 4,40

1 II • 6 II, 115 1'.,0(' J,Rn 'i,OO 3.08 4,06 3 • :11 4,3A 1 4 '7 4,44 6,00 3,7A 4,08 3,07 1Je()4 3,3n 4.37 1 4 , R 4,4? 5,98 3,77 4,<J6 3.06 4.113 3,;><J /j ' 3 5 1 4. 9 4,41 5,96 3,7A 4,95 3,05 IJ,Il1 3. ;> 'l 4,34 1'i,O lj ' 3 q 5,9'5 3,75 4,Q3 3.04 4,0(1 3,;:>7 4,32

1 'i • l 4,3A 5.93 3,71 4,<12 3,02 1,<18 3,;><; 4' 3 1 1'i,;> 4. 37 5.91 3,7? {f. ~Q() 3,0! 'J,97 3,;:>4 4,29

1 "i ' ' 4,3') '5,89 3. 71 4,RA 3.00 'J,<l'i 3,21 4.28 1'io4 4. l4 'i,ll8 3' 7rl 4,R7 2,99 1!11Q4 3,2? 4,'?7 1 "i. 5 4' 3 3 'i,R6 3 .1\ R 4,R'i 2,98 1,92 3 ' ;> 1 lj' 2 5

1'i,6 4' 31 'S,I34 j,(,7' li, ~HI. 2.97 1,9! 3,;>1') 4,24 !'i' 7 4. 30 'J,A) 3,61'1 lj, R? 2,96 ~,A9 3,j9 lj ' 2 3 j'\,8 4,29 5,81 3,1\'; 4, R 1 2.95 'J,RA 3, 1 R 4.?1 1 5 '9 4.28 5,79 3 • 611 4,79 2,94 1,R7 3' 1 7 4.20 \1',,0 .4.26 5,78 3,6? 4. 7 7 2.93 'J,R"i 3' 11\ 4' 19

1"'. 1 4,2'5 5,76 3 • 6 1 4o76 2. 92 'loR4 3, I 5 4' 17 1"-·2 4,24 5,74 3. 61'1 4,75 2,91 ~.8? 3, ! 4 4' 1 6 1 1\ • 3 4. 2 3 5,73 3.5'1 4 ' 7' 3 2.90 ~, R I :l.t~ 4. 1 5 \1'>,4 4,21 5,71 3.5~ 4. 7 2 2,A9 1,RQ 3. 1, 4 ' 1 3 !Ao"i 4.20 5,70 3.57 4,70 2,81l 1,78 3 • 1 1 4' 1 2

)1\,6 4, I 9 5.68 ,,.,, 4,1'>9 2.87 <,77 3 ' 1 rJ 4 oil 1A,7 4, 1 B 5.66 3.55 4,1\7 2,Bfl <,71> J,oq 4. 1 0 )f>,/l 4. 1"' 5,65 3.5< 4.1'16 2,fl'i <,74 ),QR 4,0fl )1\,9 4. 15 5,63 3,5? 4,1\4 2o84 1.73 3,07 4,07 17,n 4' 14 5,62 3 • 5 1 lj ' "' 3 2,83 ~.7'? 3,07 4,06

1 7. 1 4. 1 3 5,60 3.50 4,1)2 2.82 1, 7 I 3,0, 4,05 j7,;> 4.12 5,59 3,4'l 4,1\0 2.81 1,1\9 3,/l'i 4,04 17.3 4. 11 5,'57 3,4R 4,59 2.80 ,,,fl 3,04 4,02 17,4 4,oq '3,56 3.47 4,'ifl 2.79 <.67 3.0< 4.01 17,5 4,(1fl 5,54 3,41\ 4,56 2.78 1,(,6 3,0? 4.00

1 7' 6 4.07 S,<;J 3,4'; 4,55 2,77 1,A4 3./lt 3,99 1 7' 7 4,!)11 '),51 3,44 4,"i4 2'1176 1,1'13 1.01'1 1,9R 1 7, A 4.Q5 o;,so 3.41 4,'i;? 2.75 ,,1);> ;:>,99 1,97 17,9 4,()4 '5,48 3,4? 4o'il 2.7'4 '. ">1 2.9~ 1,95

TP4E I"'TtRVAL llN THIS SHEFT " () ' 1 M l ~HITt 18

TABLE 3

I~!CI1lGAN OEPARTMENT OF STATE HIGHWAYS

RAINFALL !"!TENSITY ~ DURATION TARLF (TO BE USEI:l WITH SEWFR OESTGN PROGRAM 040A0)

TIME ZONE I. 7rJNE 2 ZONE ~ 70NE 4 !N

MINIITES tn~vR 5o~vR lO~YR so~vR !O~YR 5o~vR tO~VR so~vR

111,0 4.03 5.47 3. 41 4,50 2. 7 3 1,60 2,91'1 3,94

1 ll.l 4,0;:> 5.46 3,4(') 4.48 2.72 3,51l ;?,,91' 3.93 111.2 4,01 5,44 3. 3'1 4.47 2.7'2 1.57' 2,96 3,92 18' 3 4,00 5,43 3,311 4, II 6 2.71 1,56 ;:>,95 3,91 !Roll 3.99 5.41 3,37 4 ' /j 5 2.70 3,55 2,94 3' 90 18,'5 3,97 5,40 3 ' 31\ 4 '4 l 2,69 3,'54 2.93 3,89

111,6 3,96 5' 39 3,3'5 4,42 2.68 3' '53 2.9::1 3,88 11'1 ' 7 3,95 5,37 3 ' Jlj 4,41 2.67 l,'i! 2.92 3,87 !ll.ll 3,94 5,36 3,31 4,40 2,66 3,5(1 ;:>.91 1,85 !11,9 3,93 5,35 3' 3 ::> 4,38 2.66 '!,49 2,9(1 3,84 19,() 3,9;> '5,31 3' 11 4.37 2,65 ~.48 ;>,89 3 '8 3

19.1 3,91 5,32 3 ' 3 (1 4,36 2,64 "1,47 2' llA 3,82 19,2 3,90 5,3! 3.;>~ 4.35 2,63 1.46 ;>,811 3,81 )9,3 3,89 5.29 3,;>~ 4' '/j 2,62 3.45 ;>,81 3,fl0 )9,4 3,8R 5,28 3,211 4,32 2.61 3 , 4 II ;>,All 3,1'9 19,5 3,87 5,27 3,27 4' 31 2 ' (';.l ~.43 2.85 3,78

1<:1,6 3,86 5,25 3,;>6 4,30 2,60 3,42 ;>.85 3,77 19,7 3.85 5.24 J,?'i 4,;>9 2.59 1.4! 2.114 3,76 j9,B 3,84 5,23 3,24 4.28 2 '58 3,40 2.83 3,75 jQ,9 3,83 So22 3,23 4,;;7 2,57 3,39 2.112 1,74 20,(1 3,82 5,2() 3,2? 4.?6 2,57 1,~7 2,8? 3,73

21'1.1 3,81 5.t9 3' 2 !. 4,;::>4 2,56 "1.36 2.81 ~.72 20.2 3,80 5.!8 3.21 4.;>3 2.55 "1,35 2.80 3. 71 20,3 3,80 5' !7 3,20 4,;:>;> 2,54 ~ ,34 (',79 3,70 2f1,4 3,79 5d5 3.1<l 4,;>1 2.54 ~.33 2,79 3,69 20,5 3,78 5oi4 3, I A 4.20 2.53 ~.32 ;:>,711 3,61'1

2(1,6 3,77 5.13 3' 1 7 4' j 9 2.52 3.31 2,77 3,67 211,7 3,76 5.12 3.11\ 4.)8 2,51 "1,30 (',711 3,66 20,11 3,75 5' 11 3. 1"' 4.17 2.51 3.?9 2.76 3,65 20,9 3,74 5.09 3.1'5 4.16 2,50 "1,29 2 .. , 'I 3,64 21 '0 3,73 s,os 3.!4 4.!5 2,49 3.?8 2,74 3,1\4

21,! 3. 72 5,07 3oi3 4' 1 4 2,48 ~.27 2.74 3,63 21 '2 3,71 5,()6 3.12 4. 1 3 2.48 "1,?6 2,73 3,62 21 • 3 3,70 5,05 3.t2 4.11 2,47 3,;>5 2,7? 3,61 21. '4 3,70 5,04 3 .11. 4.10 2.46 ~.24 2' 71 ~.60

21 '5 3,69 5.o2 3' 10 4,09 2o46 ~. :n 2.1'1 3,59

21 '6 3,68 5,01 3,09 4,08 2,45 ~.;>;> 2•ro 3,58 21. '7 3.67 5,oo 3.08 4.07 2.44 ~.21 2.69 3,57 21 , a 3,611 4.99 3.011 4o06 2,43 3o?O 2,69 3,56 21 '9 3.65 4.98 3,07 4,05 2.43 3.19 2.68 3,55

TI '4E INTERVAL ON THIS SHEET " 0,1 MINUTE 19

TABLE 4

MICHIGAN rlEPARTMF.:NT OF 5TATE HIGHWAYS

RAINFALL I ~I TENSITY ~ DIIRATION TARLE <TO BE USED WTTH SEWER DESTGN PROGRAM rl4080)

TIME ZONE 1 ~ONt ? ZONE 1 70NE 4 IN

MTNUTES 1o~vR so~vR to~vR ';OmYR lOmyR 5f'1~yR jrleVR so~vR

2::>.0 3,64 4,97 3,(11', 4,04 2.42 '· 111 2.67 3,'05

22,1 3,64 4,96 3,0"\ 4 '113 2,41 1, I 7 2,67 ~.54

2?,2 3,63 4,95 3,04 4,0;> 2,41 1' 1. 6 2,6f> 3,53 22,3 3,62 4,93 3,()4 4,01 2,40 ~' 1"' 2.65 3,52 22,4 3,61 4,92 3,01 4,(1() 2' 39 '' 15

2,6'l 3,51 22,5 3,60 ,, '91 3,0:> 3,99 2,39 1' 14 2' 6il 3,50

2?,6 3,59 4,90 3,0::> 3,<l8 2.31'1 1' 13 2,1\1 3,49 2?,7 3,59 4,89 3. 01 3,9il 2.37

'· 1" 2.63 3,49

2?,8 3,58 4,88 3,011 3,G7 2' 37 3, I I 2·"'' 3' il8 2;>,9 3,57 4,87 2,9<) 3,96 2.36 ~' I 0 2.6? 3,47 2::1.0 .3,56 /j' 86 2,9<) 3,95 2.35 :l, 10 ?,1\1 3,46

2 ~.! 3,55 4,85 2,9A 3,94 2.35 1,()9 2,6(1 3,45 23,? 3,55 4,84 2,97 3,93 2,34 1,(')8 2 ,e;o 3,44 2 :l ,3 3,54 4,83 2,91\ 3.9? 2.34 ),()7 2,59 3,44 23.4 3,53 4,82 2,91) 3,9) 2.33 1,06 2,511 3,43 ;n,s 3,52 4,8) 2.9'l 3,90 2,3;> 3,()5 2.51l 3,4;?

23,6 3,5! I;, B 0 2. 9/j 3.89 2.32 1,()5 ;>,57' 3,41 23,7 3,51 4,79 2.94 3,88 2' 31 1,(14 2,57' 3,40 21,1\ 3,50 4,78 2,93 3,87 2.30 3.03 2,511 3,40 23,9 3,4<) 4,77 2.92 3,81) 2,30 1,();> ;>,5'5 3.39 211' 0 3,4A 4,76 2,9';> 1,116 2.29 ~.01 ;>,55 3,38

24.1 3,48 4,75 2,91 3.85 2.29 ~.oo 2,54 3,3 7 24.2 3,47 4,74 2,91') 3,84 2,28 3.00 2. 54 3,36 24,3 3,46 4' 73 2,90 3,83 2.27 ?,99 2,51 3.36 24,4 3,45 /j '7 2 2,89 3oA2 2.27 ?,98 2 '5? 3.35 24,5 3,45 4' 7 1 2.88 3,81 2.26 ,,97 ;:>,5:;> ~.34

24,6 3,44 4.70 2,81'1 3,110 2.26 :;>,97 ;>,51 3,33 24,7 3,43 4,69 2,87 3,79 2.25 ?,<)6 2. 5 j 1,33 24.~ 3.42 4,68 2.81\ 3,79 2o25 ;>,95 2,5() 3,32 24,9 3.42 4.67 2.81'1 3,1'8 2' 211 ?,94 2,5('1 3. 3 1 25.0 3.4\ 4,66 2,85 3,77 2.23 :;>,94 2,49 3,30

25 .t 3.40 4,65 2.84 3.76 2o23 ;>,93 2,4A 3,30 2">·2 3, 'I 0 4,64 2,84 3,75 2.22 ?,92 2.48 3,29 25.3 3' 3 9 II , 6 3 2.8~ 3,74 2·22 ;>,91 2.47' 1.28 25,4 3.38 4.62 2,8::> 3,74 2.21 ?.91 2,47 3,27 2'5,5 3,37 1! '61 2,8, 3,73 2.21 ?,90 2.41'1 3,27

25,6 3.37 4,60 2,81 3.72 2.20 '·1'19 2,4il 3,26 25.7 3,36 4,59 2oil0 3.71 2' 19 ;>,1\A ;>,45 3,25 25.11 3 .3'5 4,59 2' llO 3.70 2.19 ,,118 ;>,45 3.25 25,9 3.35 4,58 ;>,7Q 3.70 2.18 '.ll7 ;>,44 3,;>4

TI 'iE !NHRVAL ON THIS SHEET ., 0 ' I MINUTE

20

TABLE 5

MICHIGAN l'lEF'ARTMENT OF STATE HIGHWAYS

RATNF"All INTENSITY m DURATION TARLE no AE USE11 WITH SEWER OESTGN F'ROGRAM 04080)

TTME ZONE 1 ;>ONE 2 ZONE ~ 7DNE 4 TN

MINIITES to~vR 50mYR to~vR so~vR !OmyR 5(1myR to~vR 50•YR

21\,0 3,34 4,57 2.7<1 3.~9 2.18 ?,ll6 2,44 3,23

21\.1 3.33 4,56 2.711 3.68 2ol7 ?,115 2. 4 ~ 3.22 211.2 3,33 4,55 2.77 3,67 2d7 ::>,1\5 :;>,4::> 3o22 26.3 3 ,3?, 4,54 2.77 3.66 2.16 ::>.84 2.4? 3,21 2flo4 3.31 4,53 2o7f> 3,66 2d6 ?,113 ;:>.41 3o20 ;:>6,5 3.31 4.52 2o76 3.65 2d5 :>,A3 2o41 3o20

21'1,6 3,30 4.51 2.7"'> 3.64 2.15 :>,A;> 2,4(1 3.19 2(),7 3,29 4,51 2.74 3,63 2. !4 ?oil! 2,4(1 3.!8 21'1,8 3,29 4,5o 2.74 3.62 2<14 i'o81 2,3Q 3. 111 26,9 3,28 4,49 2.7~ 3,62 2.13 :>.110 2,3Q 3,)7 27.0 3,27 4,48 2.7~ 3,61, 2.!3 ?,7CJ 2.3~ 3.16

27 o1 3,27 4,47 2,7? 3,60 2.12 ;>,79 2,3A 3.16 ;>7,2 3,26 4,411 2.7'1 3,59 2.12 :>,7'8 2' 31' 3.15 27'.3 3.25 4,45 2.71 3.59 2.11 '?. 77 2' 37 3.14 27',4 3,25 4,45 2,7'0 3,58 2.11 ;>.77 2,3A 3.14 21',5 3,24 4,44 2.7'0 3,'57 2.10 ;>,711 2,36 3.! 3

27,6 3,23 I;, 4 3 2,6'l 3,'56 2.!0 ?,75 ;2,35 3.!2 ;>7,7 3,23 4,42 2,6<1 3,'i6 2,0<;1 ::>,75 2,35 3.t2 27,11 3,22 4,4! 2,611 3,55 2.09 ;>,74 2,34 3. 11 21',9 3,22 4,40 2,67 3,54 2.08 :>,73 2,34 3.10 211,() 3,21 4,40 2,67 3,54 2.08 ;>,73 ;:>, 33 3.10

28.1 3,20 4,39 2,61\ 3.'53 2.07 ?,72 ;>,33 3,09 211,2 3.20 4,38 2,611 3,52 2.07 ?,7! 2.3::> 3,08 211,3 3,19 II, 3 7 2,6'5 3,51 ;:>,01\ :>.71 2,3;> 3,08 211,4 3' 18 4,36 2.6'i 3,51 2.06 ?,70 2,31 3,07 211,'5 3,18 4,35 2.64 3,50 2o05 ;:>,69 2.31 3,06

28,1'1 3' 1 7 4,35 2,64 3,49 2.05 :>.69 2,30 3,06 28,7 3.t7 4,34 2,63 3,49 2.04 :>,611 2,30 3,05 21l,B 3.16 4,33 2.6~ 3,48 2.04 ;:>,(>8 2,30 3.05 21'1,9 3o15 4,32 2,6;> 3,47 2.03 :>,67 2,29 3,04 2<1,0 3.15 4,32 2' 6, 3,46 2.03 ;>,66 2,2<l 3,03

2<1.! 3.14 4,31 ?..61 3,46 2.02 ?,66 2,28 3,03 29,2 3,14 4,30 2,60 3,45 2o02 :>,65 2.2~ 3,02 2<;1,3 3' 13 4,29 2,6(1 3,44 2o01 ;:>,1)5 2.27 3,02 2'lo4 3,J2 4,28 z,s<~ 3.44 2·01 ;>,64 2o21' ::!,()1 29,5 3' 12 4,;:>8 2,5<1 3,43 2o00 ;> ,!'\ 3 2,2'> 3.00

2'l,6 3, 11 4,27 2,51'\ 3,42 2.00 ;>,63 2,21'. 3,00 2<1,1' 3.11 4,26 2,58 3,42 2o00 ::>.62 2.2'1 ;:>,99 29,8 3.10 4,25 2,57 3.41 lo99 ;>,62 2.2'5 ;:>,C/9 29,9 3.10 4,25 2,5'1' 3,40 lo99 ? ~d) 1 2,25 2,CJ8

TIME INTERVAL nN THIS SHEET " 0,1 MINUTE

21

TTME IN

MINUTES

30,6 30~1'1 31 • 0 31 '2 31 '4

31 '6 31 '8 32,0 3;>,2 32,4

32,6 3;>,8 33,1) 33,2 33,4

33,1\

33' ll 34.0 34.2 34.4

34,6 34,8 3'5.0 35,2 35,4

3'5,6 3'\,8 311;0 36.2 36,4

31'>,6 31'\,1\ 37.0 37 '2 37',4

ZONE

3,09 3,08 3,07

3,06 3.05 3,03 3,0? 3' (Ji

3,00 2,99 2.98 2,97 2,96

2,95 2' 91! 2,93 2,9;> 2,91

2,90 2,8'l 2,88 2,87 2.86

2o85 2,84 2,83 2.82 2,81

2.81 2.80 2,7() 2,78 2' 77

2,76 2,7'5 2.74 2' 73 2,73

2.72 2.71

MICHIGAN DEPARTMENT 0~ STATE HIGHWAYS

RA !NFALL !~!TENSITY ~ DIIRATION TARLF (TO BE USED WITH SEWER DESIGN PROGRAM 0408n)

1

I!, 2 4 4,22 4,21

4' 19 4' 1 8 4,16 4,15 lj d 4

4.12 4.11 4,09 4,08 4,07'

4,05 4,04 li '0 3 4,01 4,00

3,99 3,97' 3,96 3,95 3,93

3,92 3,91 3,90 3,88 3,87

3,86 3,85 3,84 3.82 3,81

3' 80 3,79 3,78 3,77 3,75

ZONE

2.53 2,5;> 2,5! 2,50 2,4'l

2.48 2,4A 2,47 2,4A 2oii'S

2' 411 2,43 2,4;> 2,4! 2,4(1

2,3<> 2,3Q 2.31'1 2,37' 2,3A

2d'5 2,34 2' 33 2.3~ 2,3;>

2' 3! 2,311 2.2'1 2.2'l 2.2!1

2.27' 2,2A 2·2"' 2,25 2,24

3' /j 0 3,38 3,37

3. 3 6 3,35 3' 33 3,32 3.31

3,30 3,?8 3.27 3,26 3,25

3.24 3.22 3,21 3,:>0 3' 1 9

3. 1 8 3' 1 7 3.!5 3.!4 3,13

3.!2 3.11 3.10 3,09 J,ns

3,07 3,06 3,05 3,04 3,03

3,02 3,01 3.00 2,90 2,'18

!.96 1.95 1,94 1,93 1 '9 2

1 '91 1 • 91 lo90 1o8'l 1,88

1 '8 7 1,87 1 '8 6 1 '8 5 1.84

1,84 1. 8 3 1.82 1.81 1 '8 1

1.60 1,79 1,7A 1.78 1 '77

1.76 1 '7 6 1.75 1.74 1.1'4

1 '7 3 1.1'2 1 '7 2 1 ' 'T 1 1,70

;>,57 ?,56 ;>,'55 ;>,54 ;>.52

?,51 ;>,'50 ;>,49 ;>,48 ;>,47

?,46 ::>.45 ::>,411 ?,43 2.42

? '/;1 ?,40 ;>,jQ

;>,38 ;>,37

;>' 36 ;>,.35 ?o34 ;>.33 ?,3::>

?.3::> ::>' 31 ::>.30 ?o29 ;>,;>8

?.27 ;>,;>6 ;>,;>5 ;>,::>4 ? , ;>II

TIME I~TERVAL llN THIS SHEET • 0,2 MINUTE 22

TABLE 6

ZONE

;:>,;:>4 2.23 2.2::>

2.21 2.21 (',('(1 2. 1 Q

(',!R

2' 17 2.16 2,11'> ?.1'5 2' 14

2.13 2.1? 2.12 2. 1 1 2.10

2,09 2,0Q 2,011 2. 01' 2.011

2,01\ 2,05 2 ,()4 2o03 2,03

2e0~

2.01 2.01 ;:>,oo !,9Q

1,91'\ 1 , 9 A !,97' 1,96 I ' 'l <'>

II

2.97 ::>,96 ;>,95

2,'l4 2,93 ;:>,92 ;>,91 ;>,89

2,88 2,87 2.116 ;:>,85 2,84

2,R3 ::>,82 2,51 ;>,80 2,7'J

;>,7'8 2,77 2,76 2.75 ;>.74

;>,73 2.72 ? '71 ;>,70 2,69

:;>,68 '2.67 2,66 ::>,65 2.64

2,63 ::>' 6 3 2·62 2.61 2,60

TABLE 7

M!CHl\,AN DEPARTMENT OF STATE HIGHWAYS

RAINFALL INTENSITY ~ OIIRATION TARLF" (TO BE USED WITH SEWER DESIGN PROGRAM 04080)

TIME ZONE 1 ZONE 2 ZONE ~ 70NE 4 YN

MINIITES to~vR so~vR to~vR so~vR to~vR 5'l*YR to~vR 50mYR

31'\,0 2.70 3,72 2.2? 2,'l5 !.68 2.?1 1 ''l4 ?.57 3A05 2,68 3,69 2,20 2,92 ),67 2.19 1 '92 ;>,55 39,0 2.66 3,67 2.11l 2,90 ),65 2' 1 7 1 • 91 2,53 39,5 2,64 3,64 2.!"' 2.88 ),64 ? '15 1,8Q 2o51 40,() 2.62 3.61 2' 1 'i 2aB6 1.62 , ' 1 3 1 , ll A 2.49 40,5 ;:>,60 3,59 2.13 2,113 1 '6 1 2' 11 1 , A"' ?.47 4 1 '0 2.58 3,56 2.11 :;>.8! ),59 2,09 ),85 2,45 4 I , 5 2.56 3,54 2.\fl 2,79 ),58 ;>,()8 1, A 3 2,43 42.0 2,54 3.51 2,0R ;>,77 1 '57 ;>,()6 1 '8? 2. 111 4?,5 ;>.53 3,49 2.07 2,75 1. 55 2,04 1 '8 () ;:>,39 43,0 2.51 3,46 2,05 2,71 1,54 ?,1)2 1 '7 9 2.38 43~5 2,49 :l,44 2.01 2' 7l 1 '53 ::>.01 \,?'A 2,36

411' 0 2,47 3,42 2,0? ;>,69 1 '51 1 • 9 <) 1.7~'> ;>,34 44,5 2,4n 3.39 2.01 ;>,fl7 1 'so I , 9 7 1 ' 7 'i ;>,)2 4'i,O 2.44 3,37 1 '9Q ;>,65 1,49 1 '96 1 '7 4 ;>,3! 45,5 2.42 3.35 1 , 9 R 2. '"' 1.48 1 ''14 1 '7' 2.29 41',,0 2.41 3,33 1,91'; 2.~1 1 • 4 6 1 '9 2 1 '71 2.27 I~ A, 5 2.39 3,31 1.9'5 2.!>0 1 • 4 5 1 ' <) 1 \,7fl 2,21) 47,0 2.37 3,;>8 1 • C) 3 ;>,58 1,44 \,A9 1 '6'1 ;>,24 47,5 2,36 3.26 ),9? ;>,'11\ 1 '4 3 1 , 8 A \,68 ;>,22 41l,o 2,34 3,;>4 1,91 2,'\4 1.42 1 ' 8 (\ \,fl6 2.21 48,5 2,33 3,22 ),8'1 2,52 1 '41 I , 1'15 ),6'i 2.19 49,0 2.31 3,20 ),811 :(,51 1.40 1 , B 4 1 • 6 4 2.18 4'1,5 2.30 3. 18 ),87 2.49 1,39 1 '8? I , 6 3 2' 16 sn.o 2.28 3.16 ),8,., 2,47 1 '3 8 1 , R 1 1 • 6 2 ?.15 50,5 2.27 3' 14 1,84 2.46 ),36 1.79 1. 61 2' 13 51 '0 2,25 3.12 ),83 ?,44 1.35 1 '7 8 1 , 6 n 2' 12 51 '5 2,24 3. 10 1,8? 2,43 1,34 1, 77 1 • 5 <l 2.10 52,0 2,23 3,09 1 ' Ill 2,41 1 '3 3 \,75 1 '57 2,09 52.5 2.21 3,07 ),8() 2.40 ),32 1 '7 4 1 '51'> ?,07 53,0 2,20 3,05 ),7fl 2,38 1. 31 1 , 7 3 1 '5 'i 2.06 53,5 2.19 3,03 1' 77 2,37 1 .31 1 ' 7 '2 1 '54 2.05 511. 0 2.!7 3,01 1,1'<'> ;>,35 ),30 1 '7 0 1 , 5' ;:>,03 5 /j. 5 2' 16 3,00 ),7'5 2.34 1 '2 9 1 '6 9 1 '5 ;> ?.02 5'1,0 2' 1 5 2,98 ),74 :;>. 32 ),28 1 ' 611 1 • 5! ?.01 5'1.5 2d3 2,96 1 '73 2' 31 l· 27 t '6 7 1.50 1,99 5A,(l 2.!2 2.94 1,72 ;>,;:>9 1.26 1 '66 1 '5 t) 1 • Q 8 51),5 2' 1l 2.93 1 '71 2,28 1.2'5 1 • 65 1 '4 9 1 , 9 r 57,0 2.10 2,91 1 ' 7 (1 2.27 1 '2 4 t.63 1 , 4 R 1 '96 57,5 2' Of\ 2,89 1,1'\9 :;>,25 1.23 1 , 62 1 ' 4 1' 1 '94

TIME I"lTERVAL f1N THIS SHEET " 0,5 MINUTE

23

TABLE 8

'llCHIGAN DEPARTMENT OF STAT!:: HIGHWAYS

RAINFALL INTENSITY ~ DURATION TA RLF: <TO BE USEO WITH SEWER DESIGN PROGRAM f140Afl)

TI 'IE ZONE 1 ZONE 2 ZONE ~ 70NE 4 IN

M!NtiTES tn~vR 5o~vR tn~vR so~vR !O~YR so~vR lO~YR so~vR

5A,O (!,07 ;:>,88 1. 6R ;:>,24 1. 2 3 1 '61 1 ' lj 6 1 '9 3 5<l,O 2,05 2,115 1,6A ?.?! 1.21 1 • 59 I , 4 4 t ' 9 1 60,0 2.03 2.82 1. 64 2' 1 9 1.19 j • o; 7 1,11? 1 , B 9

6 I , 0 2,00 2,79 1 , II? 2, I II 1.1 A 1 • '55 1 , II 1 1 , II 6 62,0 1 '9 8 2,76 1 '6fl 2' 1 4 1.16 1.'53 1 ' 3 () 1 '8 4 63,0 !. 96 ;;>,73 I , 5 fl 2.12 I.! 5 1 '51 1' 37 t. 82 64,0 1 '9 4 2,70 1 '5"' 2,09 1.13 1 '119 1.31i 1 '8 0 65,0 1 '9:? ?.,67 1.5'5 ;>,07 1.12 1 '4 7 1,34 t.78

66,0 1,90 2,64 1 '5, ;>,()5 1.! I j,46 1,31 !,76 67,0 1,8il 2,62 1 '51 ?,()3 1 '09 1 ' 114 1 '31 1,74 6/l,O 1 '8 6 2,59 1 '5 (') 2,00 1.08 1 '4 2 t.3n 1 '7 2 69,0 1. 84 2.56 l,llA 1 'q 8 1 '07 1 , Ill 1 , 2 A 1 '7 0 7f'l,O 1 • 82 2' 511 1.47 1 '9 6 1 '05 1.39 1 '2 7 1 '6 8

7 1 '0 1 '8 0 2,51 lo4'i 1 '9 4 1 '0 4 1 ' 3 7 1 '26 l '6 6 7;>,0 1 '7 9 2.49 1,44 1 'C) 2 ),03 1 '3 6 1.24 ),64 73,0 1.77 2,47 1,4? 1 '91 1.02 1 ' 3 4 1 '21 1.62 7 lj' 0 1.75 2,44 1 ' 4 1 1 'Fl9 1 '0 1 1 ' 3 3 1.22 1 '61 7'\,o 1,73 2.42 ),3'1 \,87 1, on 1 ' 3 t 1 , ;> n ),59

76,0 1 '7 ;:> 2,40 1,31'1 1.a<95 Q,98 1.,10 1 ' 1 9 I , 57 77,0 1,70 2,37 ),37 1 'fl3 0,97 j,;:>Q 1' 1 8 1.56 78,0 1,69 2,35 j,35 I , R 2 0,96 \ '27 1.! 7 ),54 7<1,0 1.67 2,33 1' 34 I , B 0 0,95 1o?6 1.16 1 '53 fll'l,O 1,6'5 :2,3! 1,3"! 1 '7 8 0,94 1.25 1,14 1 '51

81 '0 1 '6 4 ;>,;>9 1' 3 2 1 '7 7 0.93 1 ' ;:> 3 1' !3 1 '4 9 8;>,0 1 '6 ;> 2,27 1,30 1 '75 0.92 1 '22 1.1? 1 '4 8 83,0 1.61 2,25 1 '2<l 1 '7 3 0,91 1 '21 1 .11 1 '4 7 84,() 1 '6 0 2,23 1 '2 ('\ I , 7 2 Oo91 1 ' 2 () 1 ' 1 (1 1 '115 85,0 1 '58 2.21 1.27 I , 7 0 0.90 1.19 l,O<l 1 • 4 4

86,() 1.57 2' 1 9 1.2~ ),1\9 Q,ll9 1 ' 1 8 !,OR I , 4 2 87,0 1 '55 2,)7' 1 '2"i 1 ' 1\7 0.88 1 ' 16 ),()7 1 '4 1 81'\,0 1 '54 2.15 1 '24 1 '6 6 0.87 1 ' 1 5 1 '01'. 1 '4 0 89,() 1 '53 2.!3 1 '2 ~ 1 '65 0,86 I , 1 4 \,O'i 1' 38 9(),0 1 '51 2.12 1.22 1.63 0,85 1 ,)3 1 '04 1.37

91 '0 1 '50 2.!0 1 '21 ! '6 2 0,85 1.\2 1 '0 3 \,31'> 92.0 1,49 2,08 1, ::> n 1 '61 0,84 1.11 \,Of' 1.34 93,0 1,48 2,06 1 ' 1 0 !,59 Q,83 !dO 1, 0 I 1 ' 3 3 94,0 1,46 2,05 1 , Ill 1 • 58 0.82 1 ' (') Q 1. on 1,32 95,0 1 • 4 5 2,03 1 , I J' 1 • 51' 0,82 1 , OB 1 '0 (') 1 '31

96,0 1 '4 4 2,01 1,1(, 1 • 55 0,8! j ' 0 1' 0,99 1.30 97',0 1.43 2,00 1 ' 1 '5 1 '54 0.60 1 ' () 7 0,98 1 , 2 B

TIME INTERVAL nN THIS SHEET ~ 1.0 MINUTE 24

TABLE 9

MICHIGAN OEF'ARTMENT OF STATE HIGHWAYS

RAYNF"ALL ! ~!TENS! TY m DIIRATION TAtlLF (TO BE USED WITH SEWER DESIGN PROGRAM 04080)

TIME ZONE 1 70NE 2 ZONE 1 2'fJNE 4 IN

MINIITES lOmYR SOmYR !OmVR 50-YR 10-YR 50-VR !OmVR 50-YR

9/l,O 1,42 1,98 1 ,14 1 • 'i 3 0,79 1 • (){\ (),97 1 • 2 7 100,() 1,40 1,95 1 • 1 :> I ''\1 0,711 j,()4 0,95 I , 25 102.0 1 • 3 7 1 '9 2 1 • 1 (j 1 '4 8 0,77 1.02 0,94 1.23 104.0 1 .35 1,89 !,OQ 1 '4 6 0,76 1 ' () 1 0.9:? 1 ' 2 1

106.0 1,33 1,86 1,07 1 ' /j 4 0,74 11,99 0,91 t .19 1011,0 1 ' 3 1 1 , A 3 !.O"i 1 ' ,, 2 0.7'3 1'1,98 0,8'l 1.!7 110,0 1 '29 1 '81 1 '0 4 1 ' lj 0 0,72 (1,96 0,88 1 .15 11?.0 1,27 1 • 7 8 1.0::> 1.38 0,71 11,95 0,86 1.!3 1111,0 1 '25 1 • 75 1.01 1. '36 0,70 11,93 O,R"i 1 ' 1 1

111'1,0 1,24 1 '7 3 t.oo 1 '3 4 0,69 11,'12 (),114 1 • 09 11"1,0 1. 22 1,70 0,91'1 1 '32 0,68 (),91 O,ll3 1.07 120,0 1. 20 1,68 0,97 1 '3 0 0,67 n,<JO 0,81 1 '06 !22.0 1.19 1,66 0,91'> 1 ' :? 9 0,6(, 11 ' ill\ Q,IIO 1,04 124.0 1.17 1 '6 3 0.94 1 '? 7 (),65 n,R7 Q,1fl 1 '02

126,0 1.15 1 '61 0.9~ 1 '?5 0,64 (),81', 0,7R 1 '0 l !28,0 1 .14 1 '59 0.9::> 111 ?4 0,63 n,A5 0,71 0,99 !30,0 1.12 1 '57 0.91 1 • 22 0,62 n,A4 0,71'1 0,98 132,0 1 , I 1 1,55 0,911 1 • ? 1 0,62 n,ll3 o,7"i 0,96 !34,0 ),09 1 '53 (),80 1 .19 0,61 1'\,82 0,74 (),95

136' 0 1 • 0 ll 1 '"i 1 o.Bil 1 .,) 8 0.60 !l,R! o.7~ 0,94 138,0 1,07 1 '4 9 (),87 1 0 17 0,59 0,1'\0 0,7;> 0,92 14fl,O j,O':i 1,117 0,81'> 1 Q 1 5 0.59 O,lll) 0,7! (1,91 142.0 1 '0 4 1,45 Q,8"i 1 • 1 4 0,58 11,79 o,ro 0.90 !44,0 j,Q3 1 '4 3 0,84 1 .1 3 0,57 0,78 0,60 O,Bil

146.0 1,01 1 '41 0,81 1,) 1 0.57 (1,77 0,68 0,87 141'\,0 1 '00 1,39 0,8;> 1.10 0,51\ 11,7'6 0,1'17' 0,81\ 150,0 0,99 1,38 0,81 j,09 0.56 0.76 0,66 0,85 152.0 0,98 1,36 0,80 1 '() 8 0.55 (),75 0,1\5 0.83 154.0 0,96 1,34 0,79 1 • () 7 o,54 0,74 0.64 0.82

156.0 0,95 1. 33 0,711 1 '0 6 0.54 l'l,74 0,64 0.81 158,0 0,94 1 ' 31 0,71\ 1 '0 4 0' 53 11,73 0,63 0.80 !61'),0 0,93 I, 29 0.77 1 '0 3 0,53 0 .7'2 0.6? 0,79 16?,0 0,92 1 '2 8 o,7f, 1 • 0 2 0,52 n,72 0,6! 0.78 164,0 0.91 1 '26 0,7'5 1 '0 1 0.52 0,71 0,6! 0.77

166,0 0.90 I , 25 0,74 1 '0 0 0.51 11,70 Q,60 (),76 !6R,o 0,89 I , 2 3 Q,i'4 0,99 o.5t n,ro o,5Q [),75 170.0 0,88 1 '22 0' 73 0,98 0,50 n,6Q O,'iO 0,74 172.0 0,87 I , 20 0.72 0.97' Q,50 0,69 o,51l 0,73 1'1'4.0 0,86 1.19 0,7;> 0,97 0,50 0,1',8 0,57 o.r2

!76,0 0,135 1.18 0' 71 0,96 0.49 11,68 0,57 o. T1

TIME INTERVAL nN THYS SHEET " 2,0 MINUTES 25

TABLE 10

MICHIGAN DEPART~ENT OF STATE HIGHWAYS

RAYNFALL l~ITENS!TY ~ DURATION TARLF no 8E USEO 1• ITH SEWER OESTGN PROGRAM 04080)

TTME ZONE 1 70NE ;:> ZONE ~ ZONE 4 IN

M!NIITES to~vR so~vR lOmYR 50=YR \fJmVR 50myR lOmYR '50mYR

178,(1 0,84 ld6 o.ro Q,95 0,49 !1,67 o,sr, o,ro 180,0 0,83 1 .15 Q,J'() 0,94 0,48 n,67 o,5'i 0,69 182,0 0,82 1.14 0,69 (1,93 0,48 n,61\ 0,5'\ (),68 184,0 0,8\ 1 .12 0,69 Q,'l;:> 0.48 n,t'll\ 0 '511 O,t'lB

!81\,0 0.81 1 .11 0,611 0,91 0.47 1),66 0,53 0,67 1811,0 0.80 1 • 10 0,67 0,91 0,47 n,l'l5 0,53 0,66 190,0 0,79 1 '0 9 0,<'>7 O,<lO 0,47 n,65 0.52 (),65 192.0 0,78 1 '0 7 o,66 O,f\9 0. 116 11.64 0.5::> 0.64 194.0 o,77 1 • 06 (),61'. \l,ll8 0.46 n, "'11 0,51 0,64

196,0 0,76 1 '05 0,6'\ n ,IHl 0.46 (1,64 0,51 11,1>3 198,0 0,76 1 '0 4 0,6" 0.87 0.45 n,63 0,511 n,1>2 200.0 o,75 1.03 0' 611 (),1'\6 0.45 (),63 0,51'1 0.1'>1 202,0 0.74 1 '02 0,64 0,85 (),45 '1,63 0,4G 0,61 204,0 0,73 1 '00 0.6~ o,e5 0.45 f\,62 0,4<l 0,60

206,0 0,73 0,99 0,63 0,1'14 0,44 11,6:;> 0,4'1 0,59 ?.Oil,O 0,72 0,98 (),6, n,A4 0,44 n.62 O,IIA 0,58 210,0 0.71 0,97 0,65 0.113 0,44 n,61 0,4'1' 0,58 2\:',0 0' 71 0,96 0,61 0,82 0,44 (),61 0,41 0,57 214,0 0.70 0,95 0,61 o,R2 0,43 1'1,61 0,41'1 1),56

216,0 0,69 0,94 0 '61'1 O,P1 0,43 1'1,61 0,46 0,56 218,0 0,69 0,93 0,611 o.~o 0.43 1),60 0,4'\ 0,55 .220. 0 0,6A 0,92 0,60 o,Ro 0.43 0,60 0,45 0,55 222,0 0.67 0.91 0,5'1 0,79 0.42 (),6Q 0, II "i 0,54 2211,0 0,67 0,90 o,"i<l 0.79 0,42 n,6o 0.44 0,53

226,0 0,66 0,89 0,58 (1,78 0.42 ('),60 0,44 0,53 22A,O 0.65 0,88 o,5R o,7B Oo42 (),<;9 0,43 0,52 230,() 0,65 0,87 o,5fl o.rr 0.4;> 11,'i'l 0,43 ('),52 232,0 0,64 o,A7 0,51' 0' 77 Oo41 0.59 0,43 0,51 ;>34,0 0.64 0.86 o,57 o.r6 0.41 (),59 0.4::> 0,'51

236 '0 0.63 0,85 0,57' 0,76 0.41 !1,59 0,4;> 0,50 23A,O 0,62 0,84 Oo56 o.75 0,41 (1,58 0,41 0.49 240.0 0,62 0,83 o,51'l 0,75 0.41 o.5R 0,4! 0,49

TIME INTERVAL (IN THIS SHEET .. 2,0 MINUTES

26

.;

. ;· ....,;,_

t -j I

!

I ' .I !

l • ' ,.. . : ·' . i

.· ! . • '

.. "'"' I ' -.

1-­.w .J .... ::::> 0

w. >( 0 ro <i .... z: 0 0.. w 1--0

~ ·w 0::

.... (/)

0

.. ~ ~ '"'=' -~

·o ....

·:r: (!)

w ::c

I ,1 •. ~ .. _..

500

400 ' EXAMPLE

t..:~: .. : : I , . Tc (MIN.)

200 300

200

150

50

40

30

20

10

5 4

.3

. . .· . ~. ,,. ·· ..... Height:: 100 Fl.

Longlh= 3,000 Fl. Time of concentrotion=I4Min:

' • : • • 0. :~ •

~: .... :•; q' ,' o I

; .... .

• -~ • __ .. ..;. • t

t . ~-. . f- 15; /)(\) . tL (FT.)

10,000

Nola:

. ···~=:-~~:.;.~. <. I "•• . .' :,._ .. • ,•

~· .. ~--.. :

-- .J -- w ..._>_

.q' .0:::

' . .... Use nomograph Tc for natural

basins with well defined channeLs,\::) for overland flow on bore :_ · :r: eorth,and for mowed gross road-:- .,_ side channels. : ;j:: ~

For overland flow, grossed sur~ · w . faces, multiply Tc by 2~ r. · ~- ... · .J

For overland flow, concreto or ; : .~ .. 5 asphalt surfaces, multiply Tc ·. ·:?! by0._4. ".~

For concrete channels, multiply . ~ · Tc by.o.2: .. ·::..:.:·-- ....... ; .. .-. ....... ~ .. ~r··;,; ~·

.· •')\.:· ......... ,_. :\.·-···;--·

L

5,000 z 0 -

1-­<i

3000 o:::.-' . ....z: ----2 ooo · ...__w

t . "0

I "00 ·, ·---~Z >') . ·I 0 ' . .. (.)

~. · ... : 1,000 . ll.

200

150

100

. : 1' :~ .: •. :.~-· 0

. • .: .. ..·,I : .. · .. . -· ·:~ . .

------Sosed on sludy by P. Z. Kirpich, Civil Engineering, Voi.IO, No.6, June 1940, p. 362

.. •

..

150

100

80

60 50

40

20

15

10

6 5

4

3

2·

FIG. 5'--.,.TIME OF CONCENTRATION OF Sfv1ALL •.

• "1 • ...:.

.. ~.:·:. ·: ...... -· . . .... · ...

6-l'{ . : ... . ' ,. •. , ........ ·?· .. ;. ·: .

0- .'I

·'

I,

.

i

..

'·

I •

INFORMATIONAL MEHORANDUM

Subject: Drai.nage Desi.gn

II 93 - R 1/175 - B

February 26, 1973

The Water Resources Commission has jurisdiction over alterations of watercourses and floodplains in Hichigan in order to control con­struction which would create adverse backwater effects. They have prescribed the 100-year flood as the criteria by which the effect of backwater must be considered. /

/

Our past design criteria, originally advocated by Fill/A, was to design· for a 50-year flood. At a recent joint meeting of representatives of the Water Resources Commission, FHWA, and the Department, it was agreed in principle that on future drainage structures (bridges or culverts) the design would include consideration of the backwater effects of a 100-year storm.

A new design policy will be adopted when the details of implementing a 100-year flood design are developed. In the interim all bridges

·and culverts should be checked for headwater depths created by a 100-year flood, Preliminary rainfall intensity tables for a 100-year flood design are attached for Zones 1 and 2. (Zones referred to are

· shown on Figure 6, page llo, of the Design Division's manual, "Storm Sewer Design," dated December, 1967.) Complete tables for all zones will be distributed in the next few weeks.

Where there is considerable difference in construction cost in providing for the 100-year flood as opposed to the 50-year flood, the problem should be referred to Design Supervision.

r¢· tl ~ F. J. COOK

. Engineer - Design Section I

DD-JHW:mm

Att.

n:m;;::;:

1

•

·---- --~---·

100-Yt,l\1< RAI Nr'ALL '

fH1£' Z0NE I

I 5, 0 6.53 i6oO 6.36 17 .o 6o20 IR·O 6.05 19·0 5. 9 1 20·0 5. 77 21 • 0 5.65 22 ·0 5.53 23·0 5, Lt! 24o0 5.3') 25.0 58 ~~0 26.0 5. 1 0 27·0 5o00 28·0 4·91 29·0 4·82 30·0 4. 7 4 31 • 0 4o66 32·0 4o58 33·0 4·51 34·0 4o43 35.0 4o36 36·0 4·29 37 .o 4 ·2/3 3fJ.O 4ol6 39·0 4. 10 40·0 4·04 41 • 0 3·99 42·0 3·93 43•0 3. 87 411,0 3·82 45.o 3o77 46oO 3 o72 47·0 3. 67 48.0 3o62 49·0 3. 57 so.o 3; 53 51 • 0 3·49· 52.0 3 • 4Lt

-2-

INI't:i~SITIES

ZO:'W 2

5.'-!5 5.28 5. I?. 4o9R 4.8Lj 4o7l 4.59 4, Lio

4o37 4·27 4. I 8 4·09 4o00 3o92 3. 8/i 3.77 3o70 3.63 3" 57 3.51 3 .. L!5 3,39 3.33 3·2B 3o23 3.}8 3.]3 3o08 3·04 3o00 2o95 2.91 2. 87 2. 8/i 2·80 2. 7 6 2•73 2o69

I 00- n:Ai~ I~ A I ,'JVI\LL l<'JiT:\I:;r f li':S

I'I ME ZO,\IE I ZU.~!·: ~~

··------ ·'-··-53.0 3·110 2.66 5·4 .. o 3.36 2o63 ss.o 3.32 2o60 56.0 3o2fl 2o56 57 ·0 3o24 2·53 58o0 3·20 2~~51 59o0 3 ol7 2. /t8 6o.o 3 • I 3 2. /i5

61 • 0 3. 10 2 o LJ2 62.0 3·06 2·39 63.0 3o03 2.37 64.0 2·99 2. 3/i . 65·0 2.96 2·32 66.0 2 •. 93 2o29 67 .o 2·90 2 ·27 68o0 2. 37 2o25 69o0 2. 811 2o23 70o0 2. 81 2·20 7 1 • 0 2.7 8 2. 1 8 72·0 2. 7 5 2.]6 7 3 .o 2. 7 3 2 .. 14 7'1·0 2. 70 2.}2 7 5 .o 2. 67 2o!O 7 6 ·0 2. 65' 2·08 11·0 2o62 2·06 18·0 2.60 2·04 19 ·0 2. 57 2o02' 80·0 2.55 2 •. oo 81 .o 2.52 I • 9 9 82 ·0 2. 50 I • 97 83·0 2·48 I • 95 84·0 2.45 I • 93 85o0 2 • Lt3 1 • 92 86oO 2·41 1 • 90 87 ·0 2·39 1 • 139 88·0 2. 37 1 • 87 89·0 2·35 1 • 85

. 90 .o 2o33 I • 134

(

-3-

··-· ---· ·--

1 oo-n:A1~ RAPFI\LL I NTf.N.'> IT I E:S I 00-Y[I\1~ HI\J. NI''AI.L IN 1'1-:N:.; IT II::·;

TII'1E ZONE I Z0NE 2 TIME ZONE I Z0NF. 2

91 • 0 2·31 I • 82 12t:.o I • 7 4 t , LJO

92 .o 2·29 1 • 81 129·0 I • 7 3 1 • 40

93 .o 2.27 I • 7 9 130·0 I , 7 2 I • 39 9LJ, 0 2 ·25 I , 7 g I 3 I • 0 I , 7 0 I . 3 c;

, ..

'95 .o 2·23 1 .n 132 •. o I • 6 9 1 • 37 96.0 2·21 1 <l 7 5 133.0 l • 6 8 I • 3 6

I 134·0 i .35 19'1·0 2ol9 I , 7 4 I • 67

1 9D .. o 2. 17 l • 7 3 135.0 I • 6 6 I , 3 5

99·0 2.\6 I , 7 I 136·0 I. 65 I • 3 4 100·0 2 ,j IJ l • 7 0 137·0 I , 64 I • 33 I 0 I , 0 2ol2 1 • 6 9 138.0 1 • 63 1 0 32 102.0 2.\0 1 • 67 139.0 I • 62 I • 3 I 103.0 2·09 I , 66 HO.Q I • 6 I 1 • 3 I 101/oO 2. 07 ] e 65 I 4 1 • 0 I • 60 i . 30 105·0 2·06 I , 64 l/~~~.o · I • 59 l • 29 106.0 2. OIJ I , 63 143;0 1 "53 I • 2 fl 1 07.0 2o02 I • 6 I I LJ4 .o 1 • 57 I • 2 f3

108·0 2-• 0 I I • 60 145.0 I , 56 I • 27 109·0 I • 99 I • 59 J/i6oO I , 55 I • 26 110·0 1 • 9 8 1 $58 I /i7 • 0 I , 5LJ l .26 I 1 1 • 0 1. 96 I • 57 1118•0 1 0 53 ·t .. 25

112·0 1 .. 9 5 1, 56 1''19·0 1 0 52 1 "2/J 113·0. 1 • 93 1 • 55 150.0 I ·51 .l 0 :~ /j

114·0 1 $ 92 1·54 I 51 • 0 I • 50 1 • 2<1

I 1 5 • 0 I , 9 I 1 .. 53 152.0 I • 50 I • 22 I 1 6. 0 I • B 9 1. 52 153.0 j • IJ9 i. 22 1 I 7 • 0 I • 88 1 • 5 I I 5LJ. 0 1 • 48 l • 21' 118·0 1 "g6 1 • 50 155.() I • 47 1. 20; 1 I 9 • 0 I dl5 I • 49 156.0 I • 46 . 1 • 20 120'·0 I • 8L1 I • :ll 8 157.1) I • 4 5 I • 1 9

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