HomeMy WebLinkAboutCT 02-13; FARBER; DRAINAGE ANALYSIS; 2003-09-01•
DRAINAGE ANALYSIS
CT02:..13
FOR
FARBER JEFFERSON STREET CONDO
\ Prepared for:
. Curt Farber
Prepared by:
PIRO ENGINEERING
930 Boardwalk, Suite D
San Marcos, CA.
92069
September 2003
WO.2864
hl~
f)
(
,,' •
Property-Existing Conditions
The existing property consists of a 1.15 acres gross residential lot located at the northeast comer
of Jefferson Street and Las Flores Drive in the City of Carlsbad. The property is currently
occupied by a single story, single family residence with associated paved improvements
including driveway parking areas and concrete flatwork. There is approximately 0.37 acre
(16,117 sf) of paving in the existing condition. Existing drainage for this lot primarily flows
south to Las Flores Drive although a fraction of the site currently drains west toward the freeway.
Drainage reaching Las Flores flows west in the street gutter and enters an existing ,curb inlet on
the north end of the curb :r:eturn on Jefferson Street.
Proposed Development:
The proposed development consists of a condominium building with associated driveway, patios,
recreation facilities and walkways. The impervious area of the site will be increased to
approximately 0.66 acres. Drainage for most of the site will be intercepted by a private storm
drain system and piped directly into the existing curb inlet on Jefferson Street. No other drainage
enters the site. Runoff from the northern lot is intercepted by an existing concrete driveway
which transports it to Jefferson Street.
Drainage Calculations:
According to the County Hydrology Manual the rational method of analysis should be used to
determine basin drainage flows because the overall drainage basin is less than 0.5 square miles.
With this method, flow is dependent upon the runoff coefficient 'C', the time of concentration as
well as the acreage of the basin. 'C' is used to express the percentage of rainfall, which becomes
surface runoff.
The drainage will be analyzed for the 10-year frequency storms of the 6 hours and 24 hours
duration both in the existing and developed conditions. Pipe and inlet capacities will be an~yzed
using the 100-year frequency storm.
Location:
117°20'50"
33°10'15"
For lO-year frequency storms
From the lO-year 6 hr. & 24 hr. precipitation maps;
P6=1.68", P24=3.1O"
P61P24=0.54, Use P6=1.68"
2
... --------------------------------~~~~--------
For 100-year frequency storms
From the 100-year 6 hr. & 24 hr. precipitation maps;
P6=2.60", P24=4.50"
P6IP24=0.58, Use P6=2.60"
Existing Runoff from the site for 1 O-year frequency storm
Runoff Coefficient:
From the San Luis Rey Hydrologic Soil Group Map, the site has Type A soil. From Table 2, For
the paved areas use 0.75. For the unpaved area use 0.30.
Composite C:
0.37/1. 1 5XO.75=0.2413
0.78/1.15X0.30=0.2035
Composite C= 0.45
Tc:
H=77-73=4', L=225', From nomograph Tc=2.4 min.
flow in Las Flores gutter to curb inlet.
Assume about 2 cfs flowing at average gutter grade of 5%
From county chart (Appendix X-D), 4.6 fps over 220'
T=220/(4.6)(60)=0.8 min.
Tc=2.4+0.8=3.2 min.
Use Tc of 5 minutes minimum per City Stds.
For P6=1.68 in., Il0=4.42"1hr.
QI0=(0.45)(4.42)(1.15)=2.29 cfs
Proposed Runoff from the site for 10-year frequency storm
Runoff Coefficient:
0.66/1. 15XO. 75=0.4304
0.4911.15X0.30=0.1278
Composite C= 0.56
3
.-----------------------------
Tc:
Consider flow to most northerly inlet in A2 (see drainage map).
Calculate approximate flow:
Approx. area=0.07 acres
QIO=(0.56)(4.42)(0.07)=0.17 cfs
For 2% minimum grade, asswnmg n=0.050 (see Appendix XVI A attached) depth is only 0.08'
with a velocity less than 0.5 fps. T=30/0.50/60=1.0 minute
For travel time in trunk sewer to Jefferson curb inlet:
Pipe length is 295' at 1%. Assume average size is 8" with 1.4 cfs. V=4.2 fps. .
Tc=295/(4.2)(60)= 1.2 min.
Total time 1.0+1.2=2.2 minutes.
Use Tc of 5 minutes minimum per City Stds.
For P6=1.68 in., Il0=4.42"1hr.
QIO=(0.56)(4.42)(1.15)=2.85 cfs
Must detain QIO(Developed)~Q10(Undeveloped)=2.85~2.29=0.56 cfs (see sheet 6)
Storm Drain System:
Check capacity offlat grate inlets using BPR~Chart 3
Assume minimum size of grate is 12" X 12" and minimum ponding is 0.5'
Perimeter ignoring bars: P=2(0.83)+2(.83)(0.5)=2.49'
To allow for clogging: Pe(effective)=2.49/2=1.25'
Area of opening: A=(0.83)(0.83)(0.5)=0.34
From Chart 3, Discharge per foot of effective P=1.2 cfs
For 0.5' ponding over 12" X 12" grate Q=(1.2)(1.25)=1.5 cfs
Storm Drain Capacity:
Use n=0.012, Minimum grade of 1 %
6"~0.61 cfs, 3.10 fps
8"-1.33 cfs, 3.76 fps
10"-2.35 cfs, 4.34 fps
12"-3.86 cfs, 4.91 fps
4
t .
Pipe Sizes:
For sake of simplicity use: 100 year storm, Use average Tc=5 minutes i.e. IlO0=6.85"1hr. for
each individual drainage basin and add Q' s in pipes:
C=0.56
Al=0.07 ac., QlO=0.16 cfs, QI00=0.27 cfs
A2=0.18 ac., QlO=0.42 cfs, QI00=O.69 cfs
A3=0.06 ac., QIO=O.14 cfs, Q100=0.23 cfs
A4=0.10 ac., QIO=O.23 cfs, Q100=0.38 cfs
A5=0.19 ac., QlO=0.44 cfs, Q100=0.73 cfs
A6=0.17 ac., QlO=0.40 cfs, Q100=0.65 cfs
A7=0.03 ac., QlO=0.07 cfs, QI00=O.12 cfs
A8=0.09 ac., QI0=0.21 cfs, QI00=0.35 cfs
To be conservative, larger pipe sizes may appear on plan.
Check Capacity of existing 5' Type B curb inlet on Jefferson Street that the proposed storm drain
system is connecting to. This inlet is in a sump.
Drainage Basin Area=3.17 acres (see Exhibit A)
However 0.89 acres from the site is being piped directly into the inlet. Hence only 3.17" .
0.89=2.28 acres flows to the curb inlet opening.
Assume C=0.56 calculated before for the developed condition.
Tc:
Assume 5 minutes for drainage to get off northerly lot into Jefferson Street.
Average slope of Jefferson Street is 0.5% toward curb inlet. Assume average flow is 2cfs.
From County App. X"D, V=1.8 fps., L=51 0', T=51 0/1.8(60)=4.7 minutes
Tc=5+4.7=9.7 minutes, II00=4.47"1hr.
Q100=(0.56)(4.47)(2.28)=5.7 cfs
Inlet is in sump with 12" curb; height of opening is 9". Horizontal opening is 4' for 5' TyPe ~B'
Curb Inlet.
Using BPR chart 1073.03 attached; water ponding at 7" would allow 1.4 cfsllineal foot of
opening. 1.4 cfs X 4 lineal feet=5.6 cfs -water ponds slightly over 7".
Because of the gutter depression of 6" the water depth in the street beyond the depression would
be slightly over 1".
Assume that ponding occurs at the 18" RCP going west from the curb inlet
Q100=(0.56)(4.47)(3.17)=7.9 cfs
From Headwater Chart (D-l) Hw/D=1.21
Hw=1.21 X 1.5=1.82' OK depth from gutter flowline to pipe invert is 3.57'
5
Post construction Water Quality Flows using the 85th Perce~tile Precipitation map (see attached)
For site, P=0.62"
Post construction BMPs that require numeric sizing are Storm Drain Grate~,
Bio-filter Strips and the Baffle Box.
Storm Drain Grates:
Check the largest sub-area draining to inlet for numeric sizing.
A5=0.19Ac.
For Tc=5 min., P=O.62 , , 1=1.6"1hr.
Qwq=(0.56)(1.6)(0. 1 9)=0. 17 cfs
From previous calculation, 12"XI2" grate can handle 1.5 cfs with 0.5' ponding.
Bio-filter Strips which are the sloping grass areas over which storm water flows to the inlet.
Analyze A5: For 2% minimum grade, assuming n=0.050 (see Appendix XVI A attached) depth
is only 0.08' with a velocity less than 0.5 fps.
Hence the strip has the capacity and good characteristics for filtering out pollutants.
Baffle Box:
Area entering box=0.89 acres.
The Qwq (85th Percentile) for this project is as follows:
1=7.44(0.62)5 -0.645 = 1.6 in.lhr.
Qwq=(0.56)(1.6)(0.89)=0.80 cfs
Baffle Box is designed and sized by Bio Clean Environmental Services Inc . .;
P.O. Box 869, Oceanside, CA 92049 to treat this flow.
Model #NSSB-4' -8' -84" selected which will treat approximately 5 cfs (see letter dated 10/29/03
from "Bio Clean" in the Storm Water Management Plan.
DETENTION ANALYSIS
IO-year frequency storms
Assume:
The hydrograph is triang¢ar with the common time of concentration of 5 minut~s being the peak
~d an end of storm at 15 minutes. Flow at the peak is Q 1 0=2.29 cfs for the existing condition
and QI0=2.85 cfs for the developed condition. (See ExhibitB Detention Graph)
Storage required is represented by the area between the two hydrographs.
V=252 cf.
Provide Storage Pipe between manholes for storage with a restrictor pipe out of the downstream
manhole to limit the flow to the undeveloped Q 1 0=2.29 cfs. v
6
t,
I
Check restrictor pipe of 6" and storage pipe of 48" .
For QlO=2.29 cfs. Depth in Storage Pipe:
Velocity in 6" restrictor pipe=2.2910.1963=11.67 fps
Headwater at restrictor: ,
H=d+ 1.2V sqr/2g
H=O.S+ 1.2(11.67)sqr/64.4=3.0'
Volume/foot for 48"pipe. From Kings, Table 7-4.
D/d=3/4=0.75, A=(0.64)(16)=10.24 sf
For 20' of 48" pipe, V=(20)(10.24)=205 cf
Additional storage of 60 cf provided in upstream cleanout.
Total storage=205+60=265 cf, ok 13 cf over 252 cf required
Check Headwater in 100 year storm:
Q100=(0.56)(6.85)(0.89)=3.41 cfs. Depth in Storage Pipe
Velocity in 6" restrictor pipe=3.23/0.1963=17.39 fps
Headwater at restrictor:
H=d+ l.2V sqr/2g
H=0.5+1.2(17.39)sqr/64.4=6.14' No Good
Provide 12" overflow pipe above 3.0 depth in 48" pipe.
Overali Flow depth:
At 3.0', Q=2.29 cfs
For 12" pipe with invert set at 3' depth, using Q=3.41-2.29=1.12cfs
From Chart D-l, Hw=0.61'
Total depth at downstream box=3.0+0.61=3.61'
7
S..f7;V LV)$ ,R't&'y
v~-_.
South' Oceanside
. MIC'
~ .. ~ A··?h
.. -
-
•
TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN} Coefficient, C
Soil Type{l)
Land Use
A B C D
Res i dent i a 1 :
Single Family .40 .45 .50 .55
Multi-Units .45 .50 .60 .70
Mob.ile homes .45 .50 .55 .65
Rural (lots greater th~n 1/2 acre) .30 .35 .40 .45
Commerci al (2) .70 80% Impervious .75 .80 .85
Industrial (2) .80 .85 .90 .95 90"" I mperv i ous
NOTES:
(1) Obtai n soil type from Append; ces IX-C) thru Ix-c4.
(2)Where actual conditions deviate significantly from the tabulated impervious-
ness values of 80% or 90%, the values given for coefficient C, may be revised
by multiplying 80% or 90% by/the ratio of actual imperviousness to "the
tabulated imperviousness. However, in no case shall the final coefficient
be Jess than 0.50. For example: '"'Cons'id~r"" commerci""iJr'"prope"rt"y" '0.1 "0 "5"6[f:----_. ":I"'.~' ~.~ •• -•• -.-:.--:-~ •• ~ ... _._ .. _~_ .. ~-~-. -•
Actual imperviousness = 50%
Tabulated imperviousness = 80%
Revised C = 50 x 0.85 = 0.53 ' 80
APPENDIX IX-B
-('
'\!' .
3000
2004
/0
H
'. • Tc. t/ltLJ0·38.5"
JC = hmlr 0.1' CO/1Ct:!/,N~rar/on
L = Leng/h or· warc-rsnerd
H r LJ//~re/1ce in e/c-var/on wonS'
d/c-.:.-riY4 s/o.Q/f: nne rs~~ ~pcm&x ¥-BJ 7;
L ~
./H//es ~t!!r Nou ..... s AI/';nvres
/iJ
L
2000
1800
/GOo .'.
#00
soo
2(}()
4 240
-f--/6d
2-f--/2iJ
100
!!ID
IJI)
70
/---:1--G()
SO
ZtJ
i
SAN D. EGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES NOMOGRAPH FOR DETERMINATION
OF TIME OF CONCENtflATION (Te)
FOR NATURAL WATERSHEDS DESIGN MANUAL --
....
t ,
~
COUNTY OF SAN' DIEGO .
OEPARTMENT OF SANITATION &
FLOOD CONTROL
10'·YEAR 6-HOUR PRECIPITATIOrJ
. '-16-ISOPLUVIALS OF 10-YEAR 6·UOU~ .
t .' PRECIPITATIOr~ IfJ . 'ENTilS OF At4 tr~CH
45 I t '!!~ '>~v ;.,). \. "t. \.."., l.LH ,. L. ... '""'_ 1'\1 ' '" ", "I ,n"'f'\\t \~._ t 1\' '_'.' \.......... It'" )r. '~)c::;f!a!
'\ "r."~ 1 '\ .. " <:::.:: " :q <t,.. !Ir
30' 1 \ 't 'I·:'::::..,.f"'~~~7'" > .... J.u .. ~.~-L'~~...i''<
15' If· I···, J )j}-llw'-T I \)L/_, • C I I .~'" 1,,,,:,1' "
33·
4; I I l'~~)\lqloIEGO r~:t<2Dakit.T~ )~k-wJ'I1'77Jl1 J~ 1\ r==t-
u.s. OEPARTMEN
NATIONAL OCBANIC AND ATJ,IOSPIlERJC ADMINISTRATION ,
SPECIAL STUDIES BRANCH, OFFICE OF IIvOROLOGY, N .... TIONAL WEATHER'SBRVICB ' .
30' I ' I ' 1· ... --1
1180 45' 30' 15 1 1170 . 45.' 30' 15 I 11 E
.-
COUNTY OF SAN DIEGO •
DEPARTMENT OF SANITATION , _ FLOOD CONTROL lO-YEAR -24-JIOU~R PRECIPITATlor~
F 10-YEAR 24 .. HOUR
45 ';;;> !U"IC~ ~~~ I '< .. ~
30' I ~' , ~q,.t.:.{.4..r.~ I( , ~(~.q \~....}-J.... '" \\£1-/1'0 '17~'-Id ~ Uf) Y I V
IS' I I )\ I ".FI4---..J
33·
45 1 I . ,I t.\J (1 SAlQ Dltes:::: I~--f(;
Ptep,fred by
U.S. OEPARTMErit OF COMMERCE
NATIONAL OCEANIC AND ATI.IOSPItI\RIC ADMINISTRATION
SPECIAL STUOIES bRANCH, OFFICE OF -ltyOROLOGY, NATIONAL WEATHER SERVICE
....
T l-I
30 t "I I_ f' --r . I
1180 4,' 30' lS' 1170 45' . 30' 15' 1160
..... .....
t -.
COUrrrY OF SAN DIEGO .
DEPARTMENT OF SANITATION.&
FLOOD CONTROL 1 00-YEAR6-HOU
"'20./ ISO'PLUVIALS
PRECIPITATIOr·l IN
PRECIPITATIOi~
1 ~O-YEAR 6·HOUR
45' '!!I\I!f~1 ,.:i ..... ~.:\.).I\.~-. 1 'f' ~ ~ I '·\.~""~'i\.\.':Il'\\f 1\1"~"f'~~ • r" ~ '~~ \.. t'_~nn,"l ~~l--\ 1; bi!f ... f .. ~ -~~~*\"t""'Tt'\'t I ,·S c:::::::: 'G ( t.'-,?!!
33··
U.S. DEPARTMEN~. r
NATIONAL OCEANIC AND AT. OSPHERIC ADMINISTRATION
SPECIAL STUDIES BRANCH, OFFICE OF H' DROLOQY, NATIONAX,'-WEATHER SIRVICE
30' -f I --1 -~'----'-+I--' ----1'---;-
118' 45' 30' 15' . llt 45' 30' 15' lIE
..
" ...
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION &
FLOOD CONTROL
L~5 '
30'
15 1
33°
45.1
Prepo(od by
U.S. DEPARTMEN!r OF C.OMMERCE
NATIONAL OCEANIC AND AT~OSPHERIC AD:'IINlSTRATION
SPECIAL STUDIES BRANCH, OFFICE OF HYDROLOGY. NATIONAL \YEATHliiR SERVICE .
~·3Q.---1-' -"-"---'--l~--'~: --...0..-1--____ --+-__ __ .. _. __ :1. =t= .
H H I :1> I
W
. 1180 45' 30 1 , l5 1 1170
e
e
4:5 1 30' 15' 1160
OCIlW'CIDI!
C~R"""'O
lilfOlMTU
~ounty 0/ San Diego
Irtment 0/ Publ~c Works
'Iood Control Section
lA.IO\.\.J.
11'IIIMIO~~tlI'tIII'<'C~ mwll.r.oWf
,~ MMrf&MTt:l_""IM~
JJt'/II.iII;1lMOmttaI"~ ~ff.WCtL1
.. 1I1f11t.....,.
,..,-*"' ..... ,..~".."., .......... _ .. ......., .... 'ftfr
... .f~
,., ..... ~ .. ""U .. _.,..... ••
pooow ................... '
85th Percentile Precipitation .(lnche t,
..
.... ~.
II : ..a :::
:: L
~ .s
! .a 1_.", "'" 5 11
~ .1 ..
, .1,. ! , , I 1 0 I' ! IJ~ 'I U11111tM1
15 20 50 1
• '"IENSm .. r ,rION D~JGH CHAAr
2
'"
Directtons for Application:
1) From precipitation .p. detena1nl & hI'. ar : 24 br. alOunts for-the "'ectld frequency, ThI'1 liP' are prtnted in ,the County Hydrc -'Manua' (10, 10 and 100 ,1'. lipS included 1 De.1gft and 'rocedure Hanual).
, .
2) A~u~t a hr. prlc1pftatioft (it nlClssary) that it is Within thl .. anal of 451 to 151
the 24 hr t prlcipitation. (liot ftl\pl1c."":
Plot I hr. precipitation on thQ riaht sid of the chart •
to DII.rt, ~ f Is) 0--... .
I '141
eo
Draw I line through the point plr.,101 to plotted 11nes. •
I~O it · 6) Th1s 11na 1. the intensitY-duration Curve !~iJt. £t the location betng analyzed. I :~ ______________________ _
.s ---. , .
,Ot ~ • Application Form: /() nUIIINlIIOl~,$ • 0) Selected rr,qUIIIC,Y //70 Yr,
.0 -' /.(/;5 • 3.T. titJ;?Ja
! .t ~ ~
& • 1) ' •• i·@(JJn., P~4· £:0 , ..!i. Ci,
" /.f;; Pa4
I) Ad~u.t.d ."... ,~pG ' in.
3) tc· _ ~ pain.
4.4Z 4) t. _.<4, (5 1n/hr,
,tHot Applicable to Desert Region
Tbi's -chart rl~lac.s -the tntens1 ty-, Durat1on-Frequenc1 curves used since : 19&5.. •
t
t .'
CHART 3
t-19 10
.... 9
Z • -l' ~ .
EXHIBIT 2
I , • • I '!I;~TCI~ ·7
t-etifNE(8J I : I ,,7
I • i i ; i I
i ; ! I i I
! i ! i 7 . -
-liiiil[W:11tDTH(8
) ~ I
'C 5 ti
a::: " ~ 3
a::
Ii 2
: i ! I' I . I . ~;
l ! i i V fI
I !
! ! i .
I I it i ~
P-2B+4 ~ : I If
A. AREA OF CLEAR OPENING IN GRATE
1'0 AUDII FCJR CLOGGING DIVIDE P OR
A BY 2 BEFORE OBTAINING d.
~ -~ ~
; I II i i_~
· .,1 UsEQJRVE(8)RJl-~
~. , ut: ., ~ OIlER GRATE
WITHOUT CUR8 P-2{8tL.J :z: ID
t-" Q.. o.a
-, s: 'TIfAN Q8FT.~
... WClIS
W ....
~ 04
W ti a: C)
a::: Q2 W ~
a: W ~ ~ OJ
....
0 -"0 -:c Ii: W Q
QI
I/~ ! • I ,1.1,1 I
W 3 45678910 15 20
Q DISCHARGE PER SQUARE FOOT OF EFFEcnVE CLEAR OPENING
f i
! !
1 I 1 I ,.
! ,
~
'I' I: I !; .;
I !:; ~ I . . Ii. : I ! i ! i i
USE CURVE (A) ~ DEPTHS 01IER GRATE LESS ~, Q8 FT. .
! I
I i I ;
OJ5 0.2 03 Q4 a5 Qti at OaosI.O 15 2 3
DISCHARGE PER FOOf' OF EFFECTtVE PERIMETER'
BU~EAU OF PUBLIC ROADS
RE'l AUG. 1968
HYDRAUUC CAPACITY OF GRATE
INLET IN SUMP
(7/9)
7....-;'
6-
OA~"-'--'
-I
20/0 ~_:~.IL.-____ n=.Ot75
~ __ --'O;';;'; __ 3_ 2°/"
I
2 3 4 6 7 8 9 10
DISCHARGE (C.F. S.)·
EXAMPLE:
Given: Q= 10 S= 2.5%
Chart gives: Depth = 0.4, Velocity = 4.4 tp.s.
RESIDENTIAL STREET
ONE SIDE ONLY
30 40
SAN DIEGO COUNTY
DE.PARTMENT OF SPECIAL DISTRICT SERVICES
GUTTER AND ROADWAY
DISCHARGE -VELOCITY CHART
.DESIGN MANUAL I ~~ ,A_ ~ ,/ .I.L...tIiL.._ .... JIG ___
50
.:: .... -:.. ,'.:'
1.0
. .9
. .:~.
,8
' •• 4
':'. ,
1 . , , --" . ;-": .. ".: ......
1"
'.:' ... 6
..... ,£.
iO
J-
,," >,~3 >~ .. , ... ,.~~ . ... ~., ... '~ ...... ~~' ...
", ,: ',' ~ "
·po 73~, 931
r,..(.~.
~;
. [~. -. t-! . ,
~ ~. -f.' 1.0.'
~.--r
; " .
. "'. '., . ..... '" .. :'., ;: '" ": ... / 1.0
'.9 I . : .. . . ":. ....
. ".
J
.........
......... ' .
',5
I .~ .. ...
' .• 1.5
. . , ..
~ : '.: -: "
~. :': ',. " .....
'z
t' '. -. ",' :: .... --:
2 :'::.: ':'. ~ : ..... :' . .. : .
.. . . ,'.--
1.5
, .
'. ,
.' ......
.'11 "" 8
..~ o -
:t:
i-
_ ~ J~I
',W :....! .08
::; .06
.J-.,'; : g .04
. lI.. .
. 0:." .03
OJ Il.. '.
,... .02
J-
0'" .
'0« , 0-
<t
(,') .OJ
• • ..... ;': .:.......~ .. l.l.. : ' .. 0
J-,
',.!..: ..... :, •. :::X:
'. .' <!J.
....
. ... : ......
w -:c:
'.
C J-
'u,.
o
:I: J-a.. w o
u. o
o .-t-.
.'
. -;. ............... ~.:
. ~ .. -........ '.6 '.'
.5
.15
.' '!
.' . , ,
.',. 0'
• t. ~ -........ -. ,t··.o
',' ,'.
'. ~. -, "'-.-... "
<t .'tt! L. ___ ·~\.;ol '"
" .. I /.' 3'3 {-f:... " .;:-{ ,: \; ,-.,~.
.'-1.2
BUREAU OF PUaLlC ROADS
DIVISION TWO WASH., D. C.
'. . ,6 I' • '.' . h.-=
H /t ~ I r')
/0.· ---. :r-, NOMO'GRAPH FOR OAPACITY OF GURa
OPENING INLETS AT LOW' POHlTS
J i. ,.,,.(= .. /' l
<. ;!( , e ~ .. IV,""""'"'"' e -' I'::' (~) 168 8,000 EXAMPLE .>(J ) (3) ; . ! S, US6 6,000 0-42 lllc"" (l,!! he'l ;;; ~. 0-120 eft "
144 5,000 . " ~.
4,000 a-KW -5.
IS2 0 'H' 4. 3.000 (I) i.5 8.8 4.
,'I IZO (t) 2.1 7 •• ; , : ~ ,2.,000 (3) 2.2 1.7
/ HI~
l-' ; ... ·1 ·0 It, 'Ht ~" l.
" -: ! l ,.., , . 9G .,000 , . )..: 900 ~ ...... '
84 600 2.
500
72 400
CI) ,
w 300 :r:: 1.0 (,)
~ (/)
"-(,)
z -a .... -/w ,-100 C:.. • k,I, ./' ~ > 80 ..I / ct ::J :r:: 0,' (,) GO 1.0
lL (/) 50 H': SCALE, 0 -0 a: w', .9 .... (I) qllOf. edo ... 1I1l ¥1, "totw.lt
~ {II Gtoo.,. u4 lri.ll-", S, . 8 . ,/ "'~~II/'
(S) G1GO.,. eftd , :~/~/-pto)lCil'!,t -
,/
.... _/
.7
" .' i To ... # .col' {2, or (3) ptOJict \. lIorltontoU, to leol, In t tllfll ;0 .... 5tr.J,lIt Inelin.d Ii"e t"rOClCil o olld 0 Ice'e., or ,te".n. o. .6 .6"
tII".'rotael. .G "
" .-,
/ {: , 15<
.& ... .&
-1.0 ' .5
"
12 HEAO\4!ATER DEPTH FOR
CONCRETE PIPE CULVERTS
IU'f .956 '!IITH ENTRANCE CCrreRO!...
\
C"ART' 1;)-1
Average Values of Roughness Coefficient (Manning's n)
Type of Waterwax
1. Closed Conduits(l)
Steel (not lined)
Cast Iron
Corrugated Metal (not lined)
Corrugated Hetal(2) (smooth asphalt quarterJining)
Corrugated l-1etal {2} (smooth asphal t half 1 i ni ng)
Corrugated Metal (smooth asphalt full lining)
Concrete
Clay (sewer)
Asbestos Cement
Drain Tile (terra cotta)
2. Open Channels(l)
a. Un1 i ned
Clay Loam
Sand
b. Revetted
Gravel
Rock
Pipe and Wire
Sacked Concrete
c. Li ned
Concrete (poured)
Air Blown Motar(3)
Asphaltic Concrete or Bituminqus Plant Mix
d. Vegetated (smaJ I -channel. shal Jow depths)
Bermuda. Kentucky Bluegrass. Buffalo
Mowed to 2 in.
Length 4 - 6 in.
Good stand any grass
length J2 in. +
length 24 in. +"
Fair stand any grass
Length 12 in. +
length 24 in. +"
3. Pavement and Gutters(l)
Concrete
Bituminous (plant-mixed)
Roughness
Coefficient (n)
0.015
0.015
0.024
·0.021
0.018
0.012
0.012
0.013
0.011
0.015
0.023
0.020
0.030 o._Q!lo __ _
0.025
0.025
0.01'4
0.016
0.018
0.050
0.060
0.120
0.200
0.100
0.170
0.015
0.016
APPENDI X XVI A
15
10
CFS 5
2.29 CFS 2.85 CFS
•
~ ~
5 10 15
MINUTES
RESERVOIR VOLUME=4.2 X 60=252 CF
DETENTION GRAPH
EXHIBIT B SCALE 1"=5'
TABLE 1-4 -ENTRANCE LOSS COEFFICIENTS*
Coefficient Ce to apply to velocity head V2/2g to determine loss. of head at entrance to a str~c
ture, such as a culvert or conduit.
Type of Structure and
Design of Entrance
Pipe, Concrete
Entrance head loss, h = C e e
Projecting from fill, socket end·
Projecting from fill, sq. cut end
Headwall or 4eadwall and wingwalls
Socket end of pipe
Square-edge
Rounded, radius 1/12D
;Pipe, or Pipe-Arch, Corrugated Metal
. Projecting from fill (no headwall)
Headwall or headwall and wingwalls, square-edge
Box, Reinforced Concrete
Headwall parallel to embankment (no wingwalls)
Square-edged on 3 edges
Rounded on 3 edges to radius 1i12 barrel dimension
WingwaUs at 150 to 450 to barrel
Square-edge top corner
Top corner rounded, ra(:Iius 1/12 D
*Author's NQte:
Coefficient
Ce
0.2
0.5
0.1
0.5
0.1
0.8
0.5
0.4
·0.2
0.4
0.2
The coefficients for pipes were obtained by laboratory tests wherein the invert of the pipe at the inlet end
was above the floor of the headwater pool. In nearly all field installations culverts are installed with the
invert of the pipe resting on the natural channel bed. Hence, the entrance coefficienis for the pipes listed
might require modification should future research under other condi~ions so indicate.
,.-
7-30 HANDBOOK OF HYDRAULICS
Ta.ble 7-4. For Determining the Area a of the Cross Section of a
Circular Conduit Flowing Part Full
depth of WIIter, D 0 Let.. .. •• . ,I = if and O •.. the tabulllted value. Then a.. .dt•
D .00 .01 .02 .03 .04 .Oli .06 .07 .08 .09 -. d ------------------
.0 .0000 .0013 .0087 .0069 .01011 .0147 ' .0192 .0242 .0294 .oalia
.1 .0409 .0470 .0584 .oaoo .0063 .D739 .0811 .08811 .0961 .1039
.2 .1118 .1199 .1281 .1865 .1449 .15315 .1623 .1711 .1800 .18ge
,3 .1982 .2074 .2167 .2260 .28M .245'0 .2546 .2642 .2739 .2836 .4 .2934 .3082 .8130 .3229 .3328 .8428 .3527 .362'1 .3727 .8827
.Ii .893 .408 .418 .428 .488 .448 .468 .462 .472 .482
.6 .492 .b02 .1l12 .521 .681 .1i40 .MO .559 .1169 .1i78
.7 .&87 .596 .605 .614 . • 623 .~ a .649 .6&'1 .666
.8 .674 .681 .689 .697 .704 .712 .719 ' .7211 .782 .788 .9 .7415 .71i0 .7li6 .761 .766 .771 .'17li .779 .782 .784 -. .. --_. :--
Table 7-5. For Determining the Hydraulic Radius r of the,Cross
Section of a Circular Conduit Flowing Part Full
depth of WIIter ' D Let ~._ _L .. _. _ •• _ al -if and O. -th~ tabulated value. Then r ... O,d..
D .00 .01 .02 .03 .04 .Oli .06 .07 .08 .09 -' d ---'---------------
.0 .000 ' .007 .018 ' .020· .026' .033, .089 .045 .Olil .011'1
.1 .063 .070 .071i .081 .08'1 .098 .099 .104 .110 .11/5
.2 .121 .126 .181 .136 .142 .147 .1112 .1&7 .161 .166
.3 .171 .176 .180 .185 .189· .198 .198 .202 .206 .210
.4 .2~4 .218 .222 .226 .229 .2aS ~286 .240 .248 .24'1
" .Ii .250 .258 .256 .259 .262 .• 265 ;268 .270 .278 .27/5
.6 .278 .280 .282 .284 .286· .288 .290 .292 .298· .2911
.7 .296 • 298 .299 . .800 .301 .802 .• 802 .308 .804 .804
.8 .304 ' .804 .804 .804 .304 .303 ' .803 .302 .801 .299
.0 .298 .296 .294 .292 .289 .286 .283 .219 .2~ .26'1'1
-----~~~ -"-"--_.-
, ~;,
! ,.
~ ,. !
f: ;1.,
}'
"
STEADY UNIFORM FLOW IN OPEN OHANNELS 7-31
Table 7-6. For Determining the Top Width T of the Cross
Section of a Circular Channel Flowing Part Full
depth of Wllter D LIlt .. _ ...... '.' .... ." if and Or = tabullltod value. Then T = Ora.
D .00 d .01 .02 .03 .04 .05 .06 .01 .08 .09
---------------------
.0 .000 .199 .280 .341 .892 .436 .41& .1110 .543 .572
.1 .600 .026 .650 .678 .694 .ru, .733 .751 .768 .785 .2 .800 .81& .828 .842 .854 .866 .877 .888 .898 .908
.8 .917 .921S .988 .940 .947 .91i4 .960 .966 .971 .975
.4 .980 .984 .987 .990 .993 .991S .997 .998 .999 1.000
.5 1.000 1.000 .999 .998 .907 .991S .993 .990 .98'1 .984
.6 • 980 .975 . .971 .966 .960 .954 .947 .940 .933 .925
.7 .917 .908 .898 .888 .877 .806 .854 .842 .828 .81&
.8 .800 .78& .768 .71S1 .733 .'1l4 .694 .673 .650 .626
.9 .600 .1i72 ' .543 .510 .471S .436 .392 .341 .280 .199
'fable 7-7. For Determining the Mean Depth D,,/' of the Cross
Section of a Ciroular Channel Flowing Part Full
depth of WIItor D Let ,dl~lUetor of channel -if and Oro .. tabulated value. Then D,. -O .. a.
D
d, . .00 : .01 .02 .03 .04 .01S .06 .0'1 .08 .09
-------------------I
.0 .000 .001, .013 .020 .027 .034 .040 .047 .054 .061 '
.1 .068 .• 0711 .082 . .089 .000 .103 .111 .iIS· .121i , .132
.2 .140 .147 .11i5 .162 . • 170 .177 .185 .198 .200 .208
.8 .216 .224 .282 .240 .249 .• 21S7 .265 .274 .282 .291
.4 .299 .808 ;317 .B26 .331i .84li .854 .368 .378 .383
.IS .893 .403 .413 .423 .• 434 .441S .456 .467 .478 .490
.6 ' .502 .514 .527 .540 .553 .1166 .&80 .5911 .610 .625
>.7 .6U ' .657 .674 .692 .710 .780 .760 .771 .7~3 .817 , .8 .S!l2 .S69 .897 .928 . .960· :996 1.035 1.0'18 1.126 1.180 .9 . 1.241 1.311 1.303 U02 1.613 1.768 1.977 2.282 ~.792 3.940
... Dm .. area/top width ie in reality the melln depth only When the Oiroullll' conduit is HOlvin; hlllf full or less.
e
..... ,;
~M-
'~
e
1J.7
r, \ I,
CI) ,
w
%
(,)
7--
Z --~ \ 0 -.... cr·,
W' > ..J ::J t).
~ 0
168
1t16
144
IS2
I~O
I (If::
gel
84
72
60
54
48
,/
e
CI) u..
<.)
~ -a -/w"
/ ~.
~/
q;
:r:
(,)
(I) -0
.• ~'
--~
---------:
8,000
6,000
5,000
4,000
3,000
. 2,000
1,000
800
600
500
400
300
100
80
60
50
40
4
3
2
o-"z Itu:"., (3.5 1Nt)
0.'20 eft
(I)
(2)
(~)
~ SCALE o
.t1.!.-o
2.5
2.1
2.2
H_
t .. ,
1.8
7 .•
't."
E"JTRANtE
TYPE
To v,' .e." ttl' or (3) ",.olle'
IIoriIontoJl, to leol. (I).tflen
un stroll/ht Inclin.cl lift' tlirouoll
;: ~--.(J )
, .' /
:;:
...... :'
/
a:~ '" F-cf il .. 0
C( w
%:
I) oftd 0 .cal ••• or .tlF.r •• 415 ~
IIIv.troted. -~~
--~--.,----~
(£) (3)
6.
6
~.
6. -~
4. 5. 4
.... 3.
2.
I.t) I ~, ,."
-"-.. ~--
1.0
1:0
' .!i .9
~9
.6 .8
.0
. ., , .7
.1
.6 .6 ..
.S .t\ .~
HEAD\VATER DEPTH FOR
CONCRETE PIPE CULVERT~
'fIlTH ENTRAN'CE CONTROl.
C'-lART t)-L