Frequently Asked Questions

We have collated some our frequently asked questions and their answers. If you have a question that isn’t answered here please let us know by emailing


In our day-to-day operations Stevenson works with aggregate and large plant equipment. During certain times of the year this can create dust around the quarry. We have certain mitigations in place to ensure this doesn’t become untenable.

How does Stevenson mitigate dust from our trucks on the roads in and around the quarry?

The quarry has three large off road trucks circulating the internal quarry roads watering them throughout the day. The trucks also supply water to our dust suppression systems as required. The water for this comes from our onsite water recycling plant.

When it comes time for trucks and trailers to leave the quarry we get them to use the truck wheel wash. In addition, we also use road sweeping and vacuum trucks to keep the quarry entrance clean.

How are dust levels monitored? Where are they monitored?

We have equipment onsite taking regular samples every six days over a 24-hr period. The samples are sent away on a monthly basis, the results are then shared with Auckland Council as part of our consent requirement.

There are plans to install more sampling units around the quarry to help inform our operational team on a “live” basis what our dust levels are looking like. The current unit is set up to the north of our crushing plants.

What is your current process for the containment or suppression of dust?

Our tertiary plant has a dust extraction system and we use water sprays and encapsulation where possible.

With any future plant design we will require more encapsulation around plant and conveyors. This means more water, more mist sprays and sealed internal roadways.

There has been a notable issue with dust entering our tanks and homes resulting in having to change the water filters every six weeks where it should be every six months. Does Stevenson Aggregates have anything to offer in this space?

The particularly dry weather has added to the dust experienced in the area. While not all of this is due to our quarry activities we would be happy to discuss excessive dust in water filtration systems on a case-by-case basis.