Appendix G Water and Sewer Analysis

                       WATER SUPPLY AND SEWER NETWORK ANALYSIS
Client: Noosa Shire Council                        Location: 62 Lake Macdonald Drive, Cooroy


                               Table 6 – Sewer Modelling Scenarios
                           Scenario
                                                                   Model Alias
             Year            Development Stage

             2021       Pre-development                2021_PWWF

             2021       Post-development               2021_PWWF_COVEY

             2031       Pre-development                2031_PWWF

             2031       Post-development               2031_PWWF_COVEY

             2036       Pre-development                2036_PWWF

             2036       Post-development               2036_PWWF_ COVEY



3.4 Network Assessment

There are two proposed connection points for the development to existing maintenance structures
one in the north and the other in the south on Dianella Ct as shown in the site plans in Appendix A.
The connection point drains to the existing sewer pump station CRY020. CRY020 ultimately
discharges to the Cooroy Sewage Treatment Plant. The proposed development will use DN150
gravity sewers to convey flow to the connection points.

As part of this analysis, the development and associated demand was added to the model based
on the site plans shown in Appendix A. The results from the sewer network assessment are shown
in Appendix C.

In the model provided it was identified that SPS-CRY020 utilised an outdated pump curve for the
2021 and 2036 scenarios. Upon further discussions with Callaghan & Toth it was determined that
Unitywater recently upgraded this pump station with two new pumps (Flygt NP3153 SH3-274) with
a duty flow of approximately 16 L/s. Refer to Appendix C for pump information.

In the 2021 pre-development scenarios the Flygt NP3153 SH3-274 pump model had adequate
capacity to cater for the incoming PWWF flow of 14 L/s. In the 2021 post-development scenario,
the new Flygt pumps had adequate capacity for the incoming flow of 16 L/s due to the increase in
PWWF from the proposed development.

In the 2036 pre-development scenario, the pumps had adequate capacity for the incoming PWWF
of 15 L/s. In the 2036 post-development scenario, the PWWF further increased to 17 L/s due to the
inflow of the proposed development. Due to the increased inflow a pump upgrade was required
which increased the duty flow to 18 L/s. Further modelling confirmed that with the full development
loading, the pump upgrade would be required before 2031 based on Unitywater’s current demand
forecast. However, in the 2031 post-development scenario the existing pumps at CRY020 had
adequate capacity up to a sewer loading from the development of 100 EP (assumed to equate to
the yield from lot 1 and 2 – 51 units).

Note that the pump upgrades and new selected pumps detailed in this report are indicative only
and will need to be determined at detailed design as part of a network works application.




Covey Associates Pty Ltd                     6                                    Project No: 233467
Consulting Engineers                                                              M23-0030Rpt Iss A