SWALE AT 1.0 SOUTH Stage 1 - Calculate Treatment Volume (1/1 Year Return Period) V T= Treatment Volume = A P * I / 1000 Where: A P = Catchment Area (m 2 ) = 800 V T= Treatment Volume = 21.60 m 3 /hr I = Average annual rainfall for 1/1 year strom (mm/hr) = 27 Stage 2 - Calculate Velocity (V) / Treatment Flow (Q F ) / Residence Time (R T ) (1/1 Year Return Period) Swale Dimensions MANNING'S EQUATION V = 1 Base (b) 0.75 n R2/3 1/2 S o Water Height (h A) 0.1 Side length actual (L A) 0.9 Side length - Wet (L W) 0.30 Where: answer dimension Swale height (h) 0.3 Mannings Angle Length (A L) 0.32 Roughness (n) 0.30 m -1/3 s Hydraulic Radius (R) 0.08 m Where: Cross sectional area of swale n = from CIRIA, 2004 guidance where water is running (A) 0.105 m 2 R = A/P W Wetted Perimeter of A = (b*h A)+(2*h A*h/2) Swale (P w) 1.38 m P W = A L+A L+b Swale Slope (S o) 0.0101 SO = 1 in 99 (0.0101) Velocity (V) 0.06 m/s Volume of Flow = Q F = V * A * 60 * 60 QF 22.69 m 3 /hr Where: Residence Time = (R T) = SL / V / 60 Swale Length (SL) (m) = 73 RT 20.27 mins Stage 3 - Checks - (1/1 Year Return Period) Type Purpose Pass? Velocity V < 0.3m/s yes Volume V T < Q F yes Residence Time R T > 10mins yes Comments

SWALE AT 1.0 SOUTH Stage 4 - Calculate Volume (1/30 Year Return Period) QF(1/30)= Flow of 1/30 return period = AP * I / 1000 Where: A P = Catchment Area (m 2 ) = 800 Q F(1/30)= Flow of 1/30 return period = 52.00 m 3 /hr I = Average annual rainfall for 1/30 year strom (mm/hr) = 65 Stage 5 - Calculate Velocity (V) / Swale Flow Capacity (Q SFC(1/30) ) for 1/30 Year Return Period Swale Dimensions MANNING'S EQUATION V = 1 Base (b) 0.75 n R2/3 1/2 S o Water Height (ha) 0.3 Side length actual (L A) 0.9 Side length - Wet (LW) 0.90 Where: answer dimension Swale height (h) 0.3 Mannings Angle Length (AL) 0.95 Roughness (n) 0.30 m -1/3 s Hydraulic Radius (R) 0.12 m Where: Cross sectional area of swale n = from CIRIA, 2004 guidance where water is running (A) 0.315 m 2 R = A/P W Wetted Perimeter of A = (b*h A)+(2*h A*h/2) Swale (P w) 2.65 m P W = A L+A L+b Swale Slope (S o) 0.0101 S O = 1 in 99 (0.0101) Velocity (V) 0.08 m/s Swale Flow Capacity = Q SFC(1/30) = V * A * 60 * 60 Q SFC(1/30) 91.84 m 3 /hr Stage 6 - Checks - (1/30 Year Return Period) Type Purpose Pass? Velocity V < 1.0m/s yes Volume QF(1/30) < Q SFC(1/30) yes Comments

Branch L (m) Grad (1 in?) D (mm) V (m/s) T f (min) T c (min) I (mm/hr) A P (hec) εa P (hec) Q (m 3 /s) All Q (m 3 /s) Remarks 2.00 76 18 100 1.829 0.69 4.69 51.9 0.026 0.026 0.004 0.014 Pass 2.01 76 16 100 1.940 0.65 5.35 49.7 0.020 0.046 0.006 0.015 Pass 2.02 76 15 100 2.003 0.63 5.98 47.7 0.025 0.071 0.009 0.016 Pass 2.03 76 15 100 2.003 0.63 6.61 45.9 0.025 0.096 0.012 0.016 Pass 2.04 76 15 100 2.003 0.63 7.24 44.2 0.030 0.126 0.015 0.016 Pass 2.05 10 38 100 1.254 0.13 7.38 43.9 0.000 0.126 0.015 0.010 Fail 2.05 10 38 150 1.637 0.10 7.34 43.9 0.000 0.126 0.015 0.029 Pass

PIPE DESIGN - USING RATIONAL METHOD Rational Method =Q = Flow in pipe (m 3 /s) = C * A P * I Where: C = 0.00278 (If AP is in hectares) T = duration of storm = T c AP = Impermeable Area (Hectares) Tc = Time of Concentration (minutes) = T f (of all connecting pipes) + 4mins(T e - time of entry 30 * 25.4 I = Rainfall intensity (mm/hr) = Where: into pipe system) T + 10 Tf = Time of Flow (minutes) = L / V / 60 Additional information L = Length (m) Grad = Gradient (1 in? Slope)= Determined as per CIRIA, 2005 Guidance D = Diameter of pipe (mm) V = Velocity (m/s) = interpolated from hydraulic charts εap = summation of impermeable areas for all connecting pipes (Hectares) All Q = Allowable Flow capacity of pipe = interpolated from hydraulic charts Catchment A Outfall Branch L Grad D V Tf Tc I Ap εap Q All Q Remarks 1.08 42 11 450 6.153 0.11 8.99 40.1 0.000 1.470 0.192 0.979 Pass Catchment B Outfall 1.21 5 13 375 5.046 0.02 10.34 37.5 0.000 2.689 0.294 0.557 Pass