Reference Documents - MCU23 0070

3.6      DOUGLAS LANE ROAD FLOW CALCULATION
A road flow capacity assessment has been undertaken to confirm that the external flows on Douglas
Lane do not enter the site.

3.6.1    PEAK FLOW CALCULATION

Refer to Figure 6 for the external catchment delineation and Table 10 for peak flow rates calculated
using the Rational Method. Refer to Appendix B for additional details.




                                                                 External
                                                                 Catchment
                                                                 0.13ha




                                                          Manning’s
                                                          Section



                                  Figure 6 – External Catchment to Douglas Lane

                                    Table 10 – External Catchment Peak Flows
                       63% AEP       39% AEP         20% AEP         10% AEP      5% AEP         2% AEP        1% AEP
 Peak Flow (m³/s)        0.030        0.040           0.055           0.068           0.081       0.103         0.113



3.6.2    ROAD CAPACITY CALCULATION

The Manning’s Equation has been used to undertake a road flow calculation on Douglas Lane. Refer to
Figure 6 above for the cross-section location. The longitudinal grade on Douglas Lane fronting the site
is approximately 8% and a surface roughness value of 0.015 was adopted for the pavement.

The results in Table 11 show the flows do not overtop the kerb, which is approximately 120mm high.
Refer to Appendix B for further calculation details.

                                    Table 11 – Manning’s Equation Calculation
                             Max Road Flow Depth
  1% AEP Flow (m³/s)                                                 Velocity (m/s)              DV Product (m²/s)
                                    (mm)
          0.113                      42                                  1.54                           0.07




SITE BASED STORMWATER MANAGEMENT PLAN – Revision B                                     36 & 38 DUKE STREET, SUNSHINE BEACH
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