Case Study 5 – Jingarri Karratha

Background

Although relatively small this 200 green title lot for 300 houses located near the western suburb Nickol in Karratha was completed in two stages. Stage 1 was completed in 2013 and then Stages 2 & 3 were completed together in late-2014. It was a very, very complex development in an area where costs are extraordinarily high.

The whole site is filled and to give some magnitude to the scale of the cost, just 100mm of extra fill would add more than $2 million to the development costs!

The project faced a number of challenges – not the least of which was developing land in the Pilbara with the myriad of issues ranging from a lack of contractors to significant accommodation costs. The latter were solved by building a 100-bed camp on the site. The issues of the cost of fill, and ‘M’ and even ‘H1’ class sites meant that the earthworks design for this site – all of which had to be filled – was very complex and sensitive to the cost of the fill.

Both stages were each completed ahead of the designated time and the construction of about 50 houses on each stage started before clearances were granted – a step only possible with the close working relationships with the service and local authorities, the contractor and our Client.

Action

A team approach that looked at the housing and footing details that were traced back to the fill used for the site and then after considerable effort was the key to the success of this development. By using a slightly better quality of fill and even though it was slightly more expensive the development has mostly ‘M’ class sites with some ‘H-1” areas where a smaller thickness of fill was placed on the site. Elsewhere in Karratha sites that use lessor quality of fill have sites with poorer classifications and so much more expensive footing costs.

Outcomes

This development portrays just how important it is to approach the project by starting with the ultimate product and asking just what it is that the Client is aiming to achieve. By balancing the fill quality and hence its cost with the housing footings, the development has achieved the best outcome of the lowest combined cost. The development in Karratha is perhaps a good example (albeit in more extreme conditions) of what is needed in many future Perth and Peel region developments – a proper and detailed examination of the combined or whole-of-project cost.