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Project : WIPRO LIMITED .

DESIGN OF STORM WATER DRAIN for ( ZONE -02)

Rational formula for calculating runoff Q = (C I A)

Q–Runoff in m3/secC– Co-efficient of run offI – Intensity of rainfall in mm/ hr.A – Drainage area in sq.mtrs.Run-off co-efficient for various types of surfacesOpen grounds, unpaved street : 0.10 to 0.30Parks, lawns, gardens : 0.10 to 0.25Macadam roads, pavements : 0.25 to 0.70

Asphalt pavements : 0.85 to 0.90Water tight roof surface : 0.90 to 0.95Storm frequencyIntensity of precipitation.Time of concentrationManning’s formula for calculating the size of drainQ= A x V

V = (1 x R2/3 x S1/2) / nV = Velocity of flow in m/sec.n = Co-efficient of friction, 0.013R = Hydraulic mean depth in mts.

R = A / PA = area of cross section in m2

(Top width + bottom width)/2xdepth of flow for trapezoidal SectionBottom width x depth of flow for rectangular sectionP = Wetted perimeter in metersBottom width + (2 x √2 x depth of flow) for trapezoidal section = B + 2 x √2 x DWhere D= depth of flowBottom width + 2 x depth of flow for rectangular section = B + 2DS = Hydraulic bed slope.

Location : Survey No,124/P,132/P Gopanapally , Vottinagulapally ,shreelingapally mandal , hyderbad - 510019

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DESIGN

DRAIN- A to B

Area of Sub-catchment   17,512 Sqm17512 Sqm

Intensity of rainfall " I " 100  mm/hr

"C" Run-off coefficient for Hardscape area 0.90 "C" Run-off coefficient for Softscape area. 0.60 Percentage paved area in Total Area "A1" 30%Total Paved area = 0.3 x 17512 5254 sq.mtr.Discharge = Q1 = C x I x A1Hence,

Dischage = Q1 = 0.9 x 100 x 5253.6 0.13  cum/secPercentage un-paved area in Total Area "A2" 70%Total Un-paved area = 0.7 x 17512 12258 sq.mtrDischarge = Q2 = C x I x A2Hence,Dischage = Q2 = 0.6 x 100 x 12258.4 0.204  cum/secActual total run off Q = Q 1 + Q2 0.336  cum/sec

Design of RCC drain Q = A x V

Area of flow A = B x D

Assume depth of flow for a rectangular drain ' D ' 0.4 mtrs.

Also assume breadth to depth ratio 1.75

So, breadth of drain = B = 1.75 D 0.7 mtrs.

Area of flow = A = 0.7 x 0.4 0.28 Sqm.

Wetted perimeter = P = B + 2D

Perimeter = P = 0.7 + 2 x 0.4 1.5 mtrs.

Wetted Radius = R = A / P

Wetted Radius = R = 0.28 / 1.5 0.187  mtrs.Manning’s formula for calculating the size of drain

Mannings Formulae = Q = (A X R2/3 X S1/2) / n

Where,Slope of drain = S = 1 in 300 300Mannings constant (friction coefficient) " n " for RCC Drains 0.013Design Discharge

= 0.28 x (0.187)^(2/3) x (1 / 300) ^(1/2) / 0.013 ) 0.41 cum/sec

Calculated size :-

  Width of drain is 700 mm

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  Depth of drain is 400 mmDesigned discharge is higher than the actual discharge 1.45 m/sce