PROJECT
Engineering design from re-zoning through to construction
The client needed rezoning of 19 ha and a comprehensive engineering design.
Constraints included:
Fox Environmental were involved from the initial re-zoning process through the various design and construction phases over 12 years. We provided hydraulic modelling, stormwater management, wastewater pump station design.
We built a detailed hydraulic 1D model of the development and neighbouring catchments to size stormwater pipe reticulation and basins to manage stormwater in events up to and including 50-year return period. This allowed the reviewing and setting of minimum floor levels throughout the site. We also designed a wastewater pump station and rising main to serve 190 houses and modelled the earthworks to minimise the need for imported fill.
The outcome was a 4 m deep wastewater pumpstation with a 1.3 km DN180 PE pressure main, and a 1.8 ha stormwater management area, 2.6 km of roading and associated services for this development.
We experienced unusual ground water variation across the site which made a winter construction period challenging. A progressive dewatering system was employed with discharge and collection to three basins in series to manage sediment and volume, before being pumped to a formalised first flush basin in the subdivision’s Stormwater Management Area downstream.
The Contractor staged construction with traffic management designed to enable traffic flow without closing the road. Good communication and forewarning of activities with the local road users helped to maintain understanding and avoid frustration.
Each section of road subgrade was checked to align bearing capacity with design pavement depths. Seasonal changes required continual reviews to reflect the construction period. Several road sections required geotextiles to minimise pavement depth and cost of road metals.
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