Overland Flow & OSD — New Dwelling, Inner West

Council —Inner West Council

Development — Residential — Single dwelling

Services — Stormwater Management Plan · Water Sensitive Urban Design · On-Site Detention

Year — 2021

Outcome — Approved

Background

The client had been through a pre-DA meeting with council and come away with advice that significantly constrained what they could build. They engaged Amuna to work through it.

The problem

Council's pre-DA advice required the wall-to-wall development to be cut back to accommodate an open overland flow channel — a substantial loss of floor area. On-site detention was also required.

Our solution

We reviewed the site against council's own policy and formed the view that the overland flow was minimal and could be managed within a conventional pit and pipe network rather than an open channel. We put that case to council's engineers directly, and the design was approved without the channel.

Council then imposed an OSD requirement. We substituted a rainwater tank for the detention, which satisfied council policy while giving the client usable storage rather than dead volume.

Was it approved? Yes.

Rainwater tank detail