The Water Corporation engaged Astron to undertake the management of Acid Sulfate Soils (ASS) and Surface Water Quality for the Millstream to Greenbushes Water Main Link. The monitoring included weekly validation sampling of lime-treated stockpiled drill cuttings for net acidity with the aim to utilise all treated soils on site to reduce in removal costs.
Work was undertaken over a nine week period, with an established up-gradient and down-gradient surface water monitoring point from the drilling works monitored for any changes to acidity and water quality parameters. Stockpiled and treated drilling spoils were also field tested with select samples submitted for confirmatory analytical analysis. Weekly reporting on both the soil and water was submitted to the Water Corporation, with any immediate concerns identified the day of sampling. Detailed daily ASS log sheets were recorded and submitted as documentation of the field testing efforts.
The investigation during the project indicated that no change to the water quality had occurred during the HDD works. Field and analytical validation testing of treated and stockpiled soils indicated that spoils were adequately treated, and were subsequently used onsite for bunding purposes.