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(i) Catchment Area

Compound Area = 24.18

Proposed Building Area = 217.64

Table 14.2 Manning's Coefficient, n = 0.011

= 8.28 mLand Slope, S = 37.60 %

= 0.39 min

= 15.02 mLongitudinal Grade, S = 0.13 %

= 1.03 min

Roof And Property Drainage Flow Time = 5 minRoad Inlet Flow Time = 5 min

= 11.42 min

= 6.42 min

Figure 13.3 = 140

120 140 15010.0 1.13 1.04 0.99

11.42 1.01 0.93 0.8915.0 0.72 0.65 0.62

= 0.93

Design storm based on 2-year ARIAppendix 13A a = 4.5140 b = 0.6729 c = -0.2311 d = 0.0118

For t = 30 min

Eqn. 13.2 =

= 4.59

= 98.84 mm/hrFor t = 60 min

= 4.20

= 67.01 mm/hr

= 49.42 mm

= 67.01 mm

= 33.10 mm

= 173.93 mm/hr

m2

m2

(ii) t c and t cs

Overland Flow Distance, Lo

Overland Flow Time, to = 107nL 1/3 /S 1/2

Length of Kerbed Gutter Flow, Lk

Kerbed Gutter Flow Time, tg = Lk/(40S1/2 )

tc

tcs

Since tc < 30 mins2P24h

tc

FD

ln(ARI It) a + blnt + clnt2 + dlnt3

ln(2I30) 2I30

ln(2 I60)2I60

P30 = 2 I30 x d

P60 = 2 I60 x d

P11.42 = P30 - FD(P60 - P30)2I11.42

KIRAAN HYDRAULIK UNTUK PERMOHONAN KEBENARAN MERANCANG UNTUK MEMBINA SEMULA SEBAHAGIAN 3 UNIT RUMAH KEDAI 2 TINGKAT SEDIA ADA, NO 155, 157 & 159, LEBUH CARNARVON, DI ATAS LOT 496, SEK. 22, BANDAR GEORGETOWN D.T.L., PULAU PINANG.UNTUK TETUAN EN. YEOH CHEONG GIAP

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= 239.53 mm/hr

(iii) Permissible Site Discharge(PSD)

Development I(mm/hr) Impervious Pervious Area CA Q(l/s)Status C A C APre-Development 173.93 - - 0.91 241.82 220.06 10.6Post-Development 239.53 0.88 217.64 0.71 24.18 208.69 13.9

For Above Ground Storage: (Using Open Space Area)

Eqn. 19.1a a == 63.62

Eqn. 19.1b b == 590.51

Permissible Site Discharge,PSD = 11.28 l/s

I(mm/hr) Impervious Area Pervious Area CAC A C A

5 234.9 0.90 218 0.71 24 213.04 13.9010 187.1 0.89 218 0.69 24 210.38 10.9315 151.7 0.88 218 0.63 24 206.76 8.7120 128.2 0.87 218 0.59 24 203.61 7.2530 98.8 0.86 218 0.52 24 199.74 5.48

(iv) On Site Detention (OSD)

PSD (l/s) c d5 13.90 11.28 6.19 1.96 1.72

10 10.93 11.28 5.20 2.49 1.95 Maximum SSR required

15 8.71 11.28 4.00 3.13 1.42 = 1.9520 7.25 11.28 2.82 3.76 0.8130 5.48 11.28 0.55 4.97 -0.06

(v) SSR Provided(Using OPEN RC ROOF as detention)Length of open space, L = 11.6 mWidth of open space, b = 3.4 mDepth of open space, d = 0.05 m

Area provided, A = 39.44

Volume provided, V = 1.97 > 1.95 (SSR) OK

(vi) Outlet pipesizeDifference in depth = 0.050 m

= 0.018

= 0.153 m

= 0.075 m= 75 mm

= 0.004Time taken to discharge detained water = 325 s

= 5.42 minPipe size adopted = 75mm dia

10I11.42

(4Qa/tc)(0.333tcQp/Qa + 0.75tc + 0.25tcs)

4QaQp

td Qd(l/s)

td Qd(l/s) SSR(m3)

m3

m2

m3

Area of orifice, Ao' m2

Diameter of orifice, Do'

Dia. of outlet pipe provided, Do

Area of orifice provided, Ao m2

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(vi) Check on Existing 400mm U-Drain Capacity

Upstream catchment area, A = 483.64= 0.04836 ha

C = 0.63

= 239.53 mm/hr

= 0.02027

=

= 0.03156

Invert Level, IL = 1.99 mReduced Level, RL = 3.01 mWidth, b = 0.4 mDepth, h = 1.020 mFree board = 0.15 mEffective depth, d = 0.87 mManning's coefficient, n = 0.011Longitudinal gradient = 0.00473

Hydraulic area, A = 0.232Wetted Perimeter, P = 5.45 mHydraulic radius, R = 0.043 m

= 0.177

> 0.032 OK

m2

10I18.16

Peak upstream flow rate, Qy m3/s

Total outflow, QT Qy + (PSD)

m3/s

m2

Capacity of flow rate, Qc

m3/s ( QT )