Response to information request REC13/0095

 Lot 5 Culvert: Catchment A + B (see Plan 1225-25).


 Catchment Area A                        =
                                             1.755 ha


 Q 1 00 rainfall event                   FCIA        =
                                                              1/360 x 0.94 x 155 x 1.755                     0.711 m3/s


 Cross Road culvert, 1 X 1200x300 RCBC with outlet control.


 Maximum HW                 =
                                102.579(upstream side of dwy)                 -
                                                                                   102.1 04(RCBC invert)    =
                                                                                                                OA 75m


 ke= OA, A        =
                      1.212 x 0.305             =
                                                    0.370 sqm, L      =
                                                                           4.88m


 de   =
          OA67(Q/Bi/3               =
                                        OA67 X (OAll.2i/3         =
                                                                      0.246m


 TW       =
              xsect D/S of2/C (see attached PCDrain Calculation sheet)                         =
                                                                                                   OAl1 m


 (de + D)/2       =
                      (0.246+ 0.305)/2               =
                                                         0.276m


 So 110 is greater ofOAl1 and 0.276                       =
                                                              OAllm


 HW       =
              H + 110   LSo
                        -




 OA75      =
               H + OAl1             -
                                        0.069
 H    =
          0.133


From Figure 9A-5 DTMR Road                               Drainage Manual, Q         =
                                                                                        OA6 m3/s


Q 1 00 weir flow                                              Q 1 00 flow 0.711 m3Is       -
                                                                                            OA6 m3Is piped
                                                              0.251 m3/s


Weir QI00                                1.7LH312             B   =
                                                                      4m
0.251                       :::::
                                         1.7 x 4 X .H312
H                                        (0.251 I (1.7X 4))2/3
                                         0.111m


Adopt weir capacity for a 0100 of 0.711 m3/s with 4m width, 0.111m upstream depth H and
900x300 RCBC.


Note culvert more than adequate for Q5 without overtopping as Q5                                   =
                                                                                                       0.34 m3/s vs culvert
capacity of 0.46 m3/s.




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flooding eales.doc