One the major prerequisites we need to build the houses we need to combat our housing crisis is infrastructure, without it, the development can’t occur. This post is about a highly but often forgotten element of infrastructure Three Waters – Water Supply, Wastewater & Stormwater focusing in this part again on Stormwater. However, while the previous part focused on traditional Grey Infrastructure this part focuses on Green Infrastructure.
Recently NACTO released the Urban Street Stormwater Guide with a focus on Green Infrastructure. Expanding the view of Green Streets came up in NACTO’s fantastic Global Streets Design Guide which AC has recently endorsed however it was great to read a more specialised guide on the matter. The use of Green Infrastructure is becoming a much more popular part of street design, the reason being that traditional Grey Stormwater systems are very expensive. Green Infrastructure can assist traditional stormwater systems by providing resilience & extra capacity especially in urban areas where impervious surface covers around 60% of land areas, but also by creating more vibrant streets that provide more amenity to residents/visitors as well as providing higher environmental outcomes. Green Streets improve air quality, they mitigate the urban heat island effect, increases species habitat, from small oases for birds and insects to the large water bodies that eventually receive stormwater runoff.
The guide advises to move away from thinking stormwater as waste but instead to design streets to embrace it. So what do NACTO think are the important elements to Green Streets.
- They Protect & Restore Natural Resources.
- They Promote Health, Equity & Human Habitat.
- They are Designed for Safety & Mobility.
- They are Designed for Lifecycle.
- They are Designed to help Provide Resilence.
But Green Streets are not just nice to have, they expand capacity, provide resilience & expand the life of traditional assets lowering long run CAPEX or as NACTO puts it in this case study.
In 2010, New York City estimated that updating the city’s stormwater system to control combined sewer overflows using only gray infrastructure would cost the city $6.8 billion of capital investment over twenty years. By blending gray and green strategies, the city reduced its estimated cost by $1.5 billion.
Green Streets are also integral for a city such as Auckland which is prone to storm events where traditional stormwater infrastructure is overwhelmed causing environmental/health risks as well as frustration. As streets comprise one-third or more of all land and half of the impervious surface in many cities, a huge opportunity exists to use streets better to deal with stormwater. Re-design also has benefits for users with best practice Green Streets you less chance of a car going through a puddle drenching you on the sidewalk, a need to jump over large puddles to not get wet, accessibility to a transit station becomes easier, or for the cyclists who have to cycle through the puddle.
Designing best practice cycle infrastructure can be key for Green Streets & Green Streets key for best practice cycle infrastructure, protected cycle lanes make it easier to implement permeable cycle lanes & Copenhagen lanes (Cycle lanes at a different street level) stop the pooling of stormwater in cycle lanes. Green Street design would also be a great way to implement the Million Trees Programme campaigned on by the Mayor Phil Goff as it would maximise the investment by
- Providing resilience/capacity for the existing Stormwater system providing environmental outcomes as well as saving on traditional grey stormwater infrastructure.
- Combat the Heat Island Effect lowering ambient temperatures in urban areas.
- Acting as a Carbon Sink.
- Creating high amenity neighbourhoods through placemaking.
- Lowering average speeds on streets increasing safety & amenity.
- Higher health outcomes both physical & psychological for residents.
- Reduction in localised pollution from vehicles.
- Improved Business.
- Reduced Crime.
- And more, all which are covered well in this Citylab Article – The Case for More Urban Trees & Dan Burden’s – 22 Benefits of Urban Street Trees.
During the recent AC endorsement of the NACTO Global Streets Design Guide I believe it did include the other guides of which this new guide was pictured. I sincerely hope that ADO/AT include Green Streets thinking as part of the street design guide they are currently working on for Auckland because it’s clear that Green Streets not only have higher social/environmental/health outcomes but also will save the ratepayer money in the long run its a win-win.
This new thinking of how to deal will stormwater will be integral if we are to provide for the growth to tackle this housing crisis, however again it is key that an integrated approach is taken to infrastructure where AC/AT/NZTA/Watercare/Panuku/Crown work together on each area as a complete package of Three Waters, Transport, Planning & Community/Social Services to make work & not in isolation of each other.
I would also recommend the NACTO Guide to those more interested in the area.