Shingle extracted from riverbeds is used mainly for roads. The main factors when looking for a source of shingle are the quality of the material and how long it lasts before it breaks down.
Because many of our district’s rivers have aggrading beds, extraction of shingle is considered sustainable. An aggrading river is one that has a continuous supply of shingle, sand and silt washing downstream which causes the bed of the river to build up or aggrade.
Catchment areas that contain hard basement rocks such as greywacke, volcanic basalt and argillite generally provide good quality shingle. Mudstone and siltstone catchments provide poorer quality shingle.
Extracting shingle, sand, gravel and rock
There are around 50 shingle permits currently issued in the Gisborne district. Permit holders are required to submit monthly returns to council detailing amounts of shingle extracted. This data is used to record trends and monitor the riverbeds.
Over any 12 month period up to 30 cubic metres of shingle, sand, gravel and rock can be extracted from rivers, without applying for a shingle permit, providing extractors comply with the following requirements:
- Gravel is taken from a location in the bed that is at least 2 metres from both the water channel and the riverbank.
- Excavation is not more than 500mm in depth as measured from existing material level.
- The activity does not occur within 10 metres of an existing structure within the bed.
- Resulting spoil is redistributed within the dry riverbed immediately on completion, at least 2 metres from both the water channel and the riverbank, and in a manner which does not change the profile of the riverbed.
A shingle permit is required for extractions greater than 30 cubic metres over any 12 month period.
Resource consent - shingle permit
Resource consent - sand extraction