B07056.W-01A Complete - Stormwater [As Published] · 132007.2398

Concept Stormwater Management Plan
RSL Care – Cooroy Retirement Village


3.2                Existing Catchment
3.2.1              Existing Catchment Characteristics

For the existing scenario analysis, the site was divided into two sub-catchments representing the northern and
southern gullies and discharge locations as shown in Drawing B07056-SK01 in Appendix A.

The site is considered totally pervious, with the only contribution to impervious areas being Cooroy Connection
Road to the west of the site.

Catchment areas and impervious proportions are presented in Table 3.1 below.
                    Table 3.1: Existing Sub-Catchment Areas and Percentage Impervious Values
                                                     Area            Impervious Area
                      Sub Catchment                                                         % Impervious
                                                      (ha)                 (ha)
                            North                     7.40                3.27                   5
                            South                     6.26                2.86                   5
                            Total                    13.66                   -                   -



3.3                Developed Catchment Characteristics
3.3.1              Developed Catchment Characteristics

For the developed scenario analysis the site was again divided into two sub-catchments. The divide between the
sub-catchments was located based on the alignment of proposed roads and expected bulk earthworks. The
developed scenario catchment plan is presented on Drawing B07056-SK02 in Appendix A.

Catchment areas and impervious proportions are presented in Table 3.2 below. Note, that modelling was
undertaken using the higher impervious percentage value shown in the table and is therefore conservative.
                   Table 3.2: Developed Sub-Catchment Areas and Percentage Impervious Values
                                                     Area            Impervious Area
                      Sub Catchment                                                  % Impervious*
                                                      (ha)                 (ha)
                           North                      7.00                 2.33         35 (33)
                           South                      6.58                 3.02         50 (46)
                        Entrance Rd                  0.089                0.036         45 (41)
                           Total                     13.59                   -             -
                                    * Actual values (bracketed) rounded up to nearest 5%.




B07056.W-01A.doc                                                                                           Page 5