Taking a medium dive into Auckland Council’s Development Contributions Policy Assumptions for 2025: 14 November 2024

“🏘️ Taking a medium dive into Auckland Council’s Development Contributions Policy assumptions for 2025: Item 1 …

I looked at numbers so I could see if the assumptions made sense to me.

It is important because the plan is to install a Greenfield’s quality stormwater system into Tamaki at roughly $800m paid for by today’s new homebuyers to rectify and develop land that doesn’t seem to have a system that enables growth.

Legacy factor: they’re still using a legacy assumption that every detached or duplex house creates 292m² of impervious surface area. Today’s compact homes? Often less than 70m² actual coverage including their share of a driveway & JOAL. Is this figure being used to calculate stormwater demand creation? I don’t know but would like to know.

Even more interesting – Council’s policy assumes:

90% impervious surface coverage in fully developed areas because that is the trend,
and,
“No meaningful on-site developer mitigation” possible on small sites

Reality check:
✅Unitary Plan actually limits coverage to 60-70% max
✅ Developers are regularly required install detention tanks ($10k each) to manage stormwater flows as a condition of their consent
✅ New driveways require drainage systems
✅ Many developments are required to achieve below pre-development stormwater levels

In Tamaki, with proposed stormwater fees of $79k per dwelling, these assumptions could mean new homeowners paying for 4x their actual impact. Time for some updated demand factors? 🤔

I don’t know the answer as not enough information has been provided by the council. While I have found a lot of data on the internet it is difficult to manipulate and I don’t necessarily understand some of it because I have never worked for the council.

That said, this is one of the points I have queried showing my calculations and will submit tomorrow.