Table- Stormwater Calculations

PIPED DRAINAGE SYSTEM BASED ON FOLLOWING ASSUMPTIONS :
ARI =                                                                  20 Years                RUNOFF COEFFICIENTS :
DURATION =                                                              5 Mins.                ROOF AREAS :                   1.00
INTENSITY =                                                           253 mm/hr                PAVED AREAS :                  0.90
MIN. PIPE GRADIENT :                                                  1.0 %                    PERVIOUS AREAS :               0.77
                                                                                                                     Runoff                            Accumulated
Name              Description       Surface IL        Upstream IL           Downstream IL      Catchment Area        Coefficient     Flow Rate         Flow Rate            Minimum Pipe Requirement
                                                                                                                                                                                      Slope %       Capacity
                                         (m)                 (m)                  (m)                (sq.m)                              (L/s)              (L/s)         Size (mm)    (min)          (L/s)
                  Legal Point of
Out/A             Discharge                    9.09               8.09             -                          2490            1.00         174.99                174.99 existing
1/A               Detention Tank               9.28               9.03                  8.27                  2490            1.00         174.99                174.99        375              1        290
                                                    From 3/A = 9.09,
2/A               Gully Pit 1                  9.22 From 1/B = 8.92                     9.06                  968             1.00             68.03              68.03        225              1         70
3/A               Gully Pit 1                  9.90         -                           9.20                  230             0.77             12.45              12.45        150              1         26

1/B               Trench Drain      10.58 to 9.22                   10.28               8.92                   738            0.90             46.68              46.68        225              1         70
1/C               Gully Pit 1                8.95             -                         8.55                  1177            1.00             82.72              82.72        300              1        160
1/D               Spel Puraceptor            9.30                    8.79               8.72 spill                            0.90         -                 -                 150              1         26
2/D               Gully Pit                  9.21                    8.89               8.86 spill                            0.90         -                 -                 150              1         26
3/D               Gully Pit                  9.21                    8.97               8.94 spill                            0.90         -                 -                 150              1         26
4/D               Gully Pit                  9.31                    9.08               9.05 spill                            0.90         -                 -                 150              1         26
5/D               Gully Pit                  9.60             -                         9.15 spill                            0.90         -                 -                 150              1         26
                  Legal Point of
Out/E             Discharge                    8.45                  7.85          -                          385             0.77             20.83              20.83 existing
1/E               Field Inlet Pit              9.08                  8.54               7.93                  232             0.77             12.55              20.83        150              2         35
2/E               Field Inlet Pit              9.38           -                         8.61                  153             0.77              8.28               8.28        150              1         26