Response to oustanding issues Animal Husbandry MCU12/0184

                                                                                            ~
                                                                                         Callaghan & Toth

Farm contour benches which form the existing catchment that drains all runoff to existing
dams at the base of each valley. The dams 1 & 2 shown on plan Plan 01 will have a 5m wide
broad crest weir spillway which will alternate flows to be equal to pre-development
concentrations.


The dam modifications have been modelled to act as a detention basin. The spillway size is
sufficient to reduce the increase in runoff from the roofs (Table 5.1) for a 05, 010 and 0100
storm back to predevelopment levels as shown in Table 5.2. Refer to attached Detail
detention basin calculations for 010 Pre and Post development flow calculation for Dams
and Roofs in Appendix 5


        TABLE 5.1:             Pre-Development and Post Development Discharges

 Location                                                  Q5             Q10                 Q100
 Pre-Development Roof Area                           0.538 mJ/s O. 38       mJ/s 1.0< 2          m3/s
 Post Development Roof Area                          0.769 mJ/s O. 51       m3/s 1.2 7           m3/s
 Roof Flow Increase                                  0.231 mJ/s       0.221 mJ/s            0.135 mJ/s


        TABLE 5.2:             Pre Dam Spillway and Post Dam Spillway


 Location                                                 Q5              Q10                 Q100
 Pre-Dam 1 &2 Spillway                              2.200 m3/s 2.5           m3/s 4.50           m3/s
 Post Dam 1 &2 Spillway                          Spillway depth      Spillway depth       Spillway depth
                                                         0.24m           0.26m                0.42m


                                                    1.81 m3/s           1.90 m3/s           3.49 m3/s
 Dam 1 &2 Spillway flow                             -0.39 mJ/s          -0.68 mJ/s          -1.01 mJ/s
 Decrease


The detention effects of Dam 1 & 2 spillways in all cases reduce the flows by more then the
increase in flow caused by the shed roofs.


As there are existing gravel roads already along the ridges the effect on runoff from the new
gravel roads is considered to be similar to the runoff from the existing roads.




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1209 Animal Husbandry   -
                            Top Forestry Rd. Ridgewood                                SWQMP_REV_3
September 2013