A Stormwater Management Plan must be submitted for all applications proposing new buildings, and where alterations and additions to an existing building will result in a net increase of more than 50m²of hard surface area on a site (excluding land in Warriewood Valley Land Release Area). The plan must demonstrate:

• the direction of water flows on all surfaces,
• any existing or proposed water collections points/methods
• any existing or proposed water reuse systems
• any existing or proposed connections to Council’s stormwater infrastructure
• the size, location and design of any required on-site detention tank or basin
• the size, location and design of any required rain garden
• the size, location and design of any required rainwater tank
• existing and proposed impervious area and percentage change in existing and proposed impervious area
• consistency with any relevant BASIX recommendations.