Swale Clearing

Dry Hills Estate Vineyard, Blenheim

Swales are one of those things that are easy to forget about, until they stop working.

DirtPro carries out regular swale maintenance at a Dry Hills Estate vineyard, clearing a 500-metre swale every one to two years to keep water moving freely across the site. Using the Hitachi ZX55 mini excavator, the full length can be cleared in a single day.

The blockage on this site builds up over time from a combination of vegetation growth and algae, gradually reducing the swale's capacity to carry water. Left unchecked, debris accumulates at the culvert at the end of the swale, and once that blocks, water has nowhere to go. It backs up, spills over, and starts eroding the surrounding land.

A day's work every couple of years is a small investment compared to the cost of repairing erosion damage or a washed-out culvert.

How do you know when your swale needs clearing?

• Water pooling or moving slowly after rain
• Visible vegetation or algae growth along the swale floor
• Debris building up at culvert or outlet points
• Erosion appearing at the swale edges

If you've got swales on your Marlborough property that haven't been touched in a few years, it's worth getting them looked at before the next big rain event.