Hornsby Flood Management Conditions

69. Creation of Easements (modified - Mod B) The following easements are to be created on the title of the property in accordance with Conveyancing Act 1919: a) At Stage 1, a drainage easement over the relocated RMS pipeline in accordance with the requirements of the TfNSW. b) At Stage 1, a drainage easement over the overland flow path associated with the RMS easement for a 100 year average recurrence interval storm. c) Where relevant to each of Stages 1, 2, 3, 4 and 5 of the development the creation of an appropriate "Positive Covenant" and "Restriction as to User" over the constructed on-site detention/retention systems, water quality system and outlet works, within the lots in favour of…

25. Stormwater Drainage (modified - Mod A & B) (modified - Mod B) The stormwater drainage system related to each of Stages 1, 2, 3, 4 and 5 of the development must be designed in accordance with AUS-SPEC Specifications (www.hornsby.nsw.gov.au/property/build/aus-spec-terms-and-conditions and the following requirements: a) Connected directly to an on-site detention and water quality treatment system and subsequently the internal drainage system. b) Existing depressions and watercourses proposed to convey catchment areas from upstream shall be designed and constructed to contain the major overland 100-year Average Recurrence Interval (ARI) storm event. c) All proposed habitable floor levels…

54. Stormwater Drainage (Mod D) The stormwater drainage system for impervious areas within the site must be designed and constructed for an average recurrence interval of at least 20 years and be gravity drained in accordance with the following requirements: a) Impervious areas to be connected to the existing internal drainage system and the proposed on-site detention system, draining to the natural watercourse drainage system. b) In order to avoid nuisance flooding, upstream flows are to be captured by a swale drainage system capable of draining the 100 year average recurrence interval (ARI) upstream storm flow and conveyed overland to a Council-controlled drainage system. c) All pits are…

5. Not be constructed in a location that would impact upon the visual or recreational amenity of residents. Reason: To manage stormwater flows to minimise potential flooding. Water Savings Urban Design A Water Saving Urban Design (WSUD) is to be constructed generally in accordance with the submitted “Stormwater Concept Plans” prepared by Telford Civil Consulting Engineers, Revision “I”, dated 30 July 2025. The Water Quality Targets as detailed within the report and Hornsby Development Control Plan 2024 are to be achieved in the design and supported by a MUSIC model. Reason: To manage the quantity and quality of stormwater to better protect the local environment and waterways. Internal…

2. Overland flow or any bypass from the stormwater drainage systems on site must be spread evenly over the site so as not to discharge water in a concentrated manner onto adjoining land.