Reference Document - Flood & Stormwater Management Plan 28_8_2025

                 Table of Contents
                 Executive Summary ................................................................................ 2

                 1.    Introduction ..................................................................................... 6
                       1.1     Site Characteristics ................................................................................ 6
                       1.1.    Flood Overlay ......................................................................................... 7
                       1.2.    Lawful Point of Discharge .................................................................... 8
                       1.3.    Request for Information ....................................................................... 9
                               Item 10: Issue – Earthworks ..............................................................................9
                               Item 11 9
                               Item: Flood impact assessment ........................................................................9
                               Item 16 / 17 ...................................................................................................... 10
                               Items – 8 - 20.................................................................................................... 10
                               Item 21 11
                               Item 23 / 24 ...................................................................................................... 12
                       1.4.    Further Advice 7 November 2023 ..................................................... 13
                               Issue - Stormwater Quality ............................................................................. 13
                               Information Request........................................................................................ 14
                               Detention Basin ................................................................................................ 15
                       1.5.    DA Approval Conditions 3 June 2025 ................................................ 17
                               Condition 22 - Flooding .................................................................................. 18
                               Condition 23 - Flooding .................................................................................. 18

                 2.    STORMWATER QUANTITY.............................................................. 19
                       2.1.    Hydrologic Assessment ...................................................................... 19
                               2.1.1.        Existing Scenario .............................................................................. 19
                               2.1.2.        Rational Method Check ................................................................... 20
                               2.1.3.        Developed Scenario ......................................................................... 21
                               2.1.4.        Mitigation Scenario.......................................................................... 23
                       2.2.    Flood Investigation .............................................................................. 25
                               2.2.1.        Flood Model ...................................................................................... 25
                               2.2.2.        Existing Scenario (E05) .................................................................... 25
                               2.2.3.        Proposed Scenario (P08) ................................................................. 25
                               2.2.4.        Afflux .................................................................................................. 25
                               2.2.5.        Peak Flow .......................................................................................... 26
                               2.2.6.        Flood Storage ................................................................................... 26
                               2.2.7.        Flood Immunity ................................................................................ 27

                 3.    STORMWATER QUALITY ................................................................ 29
                       3.1.    Design Objectives ................................................................................ 29
                       3.2.    Stormwater Quality Treatment ......................................................... 29
                               3.2.1.        Strategy ............................................................................................. 29



                 23-0167SMP01-V4 | Stormwater Management Plan | 33 Pavilion Street, Pomona

Document Set ID: 24092538
Version: 1, Version Date: 02/09/2025