Trees love Firth's permeable products

With responsibility for the maintenance of Kell Park, Auckland Council were concerned about the lack of parking and the flow of traffic through the car park for this popular destination for dog walkers and the like.

Contracts Manager for Asset Construction Ltd, Richard Scott explains how they became involved with making the improvements to the amenities. “Asset Construction were awarded both the design and build contract for these improvements to the car park. Auckland Council’s original intention was to remove a protected tree to fit in the additional parking and roadway, but after further consideration, Council requested us to explore options to still meet the project brief, but also protect the heritage tree.”

After some lateral thinking by Asset Construction Limited, consultation with arborists and Asset Construction Limited’s engineering design partner ‘Envivo’, Richard says they came up with a plan. “It’s not only the area immediately under and around the tree that we needed to consider, which we did cater to with a timber boardwalk that has been stained to match the colour of the asphalt, but a much wider area called the root zone - an area that must have filtration to allow rain water to get to the root system of the tree.”

Richard says that in looking at all systems and products available Firth FlowPave was chosen for the paving in the root zone because it looks great and exceeded the required filtration properties. However due to the traffic that would be using the roadway, a permeable concrete base below the paving was used to give the additional pavement strength whilst allowing the water to get through to the tree’s root system.

“Firth FlowPave is a pavement system that combines permeability with a structural capability making it an ideal solution for the situation encountered here,” says Stuart Girvan, Technical & Specification Advisor (Masonry) for Firth.  “We worked with Asset Construction Limited to develop a solution that Council would be happy with.”

“If you look at the images you can see a white band around the paved section,” says Richard. “This is a concrete perimeter beam which was used as a separation between the permeable system and the standard hotmix pavement. The permeable pavement consisted of 175mm of Firth’s 19mm permeable concrete, a layer of geotextile, 30mm of 2/7 graded chip and we finished with the 80mm thick Firth FlowPave units.”

”We saved the tree with the use of Firth’s permeable product range and some design,” adds Richard. “I hope the tree knows how much effort went in to keeping it healthy and safe.”

Principal: Auckland Council 
Designer: Asset Construction Limited 
Consultants: Envivo Planners and Consulting Engineers
Contractor: Asset Construction Limited 
Location: Kell Park, Albany 
Products: Firth FlowPave and Firth Certified Concrete® - 19mm pervious concrete