How they work

Peter and his company work with lots of other organisations when they are designing a wetland. They work with engineers, ecologists, landscape architects and others to design, construct and maintain a wetland. This large group usually creates the wetland for a property developer, a local council or a government agency. Peter says that each wetland is different - rocky, sandy, hilly or flat - so his company has to be versatile and creative to meet many different challenges.

How they do it: the design process

Concept design

When Peter's company starts designing a wetland they are usually given a plan of the site by the surveyors showing the slope of the land. The design process starts with a quick sketch over this plan to figure out where the water might flow in and out and where it will travel. This initial idea is developed into a concept design to show councils and developers for approval. The team uses this design to work out how much the project might cost, how much earth needs to be moved and how many plants will need to be put in. Computer modelling is sometimes used to analyse the pollutant that will come into the wetland and how well the wetland will clean the water. Sometimes the size or shape of the wetland will need to change so that it can effectively clean the water flowing through.

Detailed design

Once the concept design is approved by everyone, a detailed design is made. This has cross sections of the wetland showing the exact shape of the wetland, how much earth needs to be removed and taken away and how many plants need to be put in. This plan is very detailed and can be many pages - but it needs to be approved before the wetland can be constructed.

Construction

Then the big trucks move in to dig out the dirt and make the wetland. Concrete and construction companies build pits and pipes or install pumps for irrigation. Smaller companies do the final shaping, add the topsoil and put the plants in. Once everything is planted there are usually a couple of years of maintenance and management needed to complete the wetland.

Constraints and challenges

Each wetland presents different constraints and challenges for the designers. The Blue Hills wetland at Glenmore Park in western Sydney provided an interesting challenge for Peter's company. The site for the wetland had power poles through the middle of it that needed to be accessible by trucks. Strict rules about power poles meant that there could be no sprinklers or water underneath them. The wetland had to look good because the property developer was building houses around it. And it needed to have a thirty metre wide corridor of land through it to provide a wildlife corridor for animals. It also needed to be safe for children and have gently sloping edges.

"There were a lot of things involved and each one dictated the shape of the wetland, the size of the wetland and the timing of how quick it took to build and the expense of building it.

A wetland ecologist in the Blue Hills team had to interact with all facets of the design team as people tried to put their brief together and work together to try to maximise the environmental outcomes. Because with every constraint there was also opportunities so the capacity to try to maximise the environmental outcomes from a constraint to an opportunity was very significant in the design process.

The primary designing force was water quality so that the primary function of the Blue Hills system is to clean water. Whenever property development goes in water is dirtier down the creek system than it would have been without it, so that the primary reason a wetland like Blue Hills goes in is to clean the water, to try to minimise or reduce the impacts of property development on the creeks and the dams and the river systems."