To provide earthworkers with an understanding of erosion and sediment control.
To ensure that the erosion and sediment controls are put into practice to minimise any adverse environmental effects during any earthwork activities.
Some general points on erosion are:
- Erosion is a process by which earth is loosened and removed by wind and water.
- Natural erosion occurs slowly.
- Erosion can be accelerated by human activities.
The main factors influencing erosion are:
- soil type
- surface cover
- topography
- climate
The main forms of erosion associated with earthworks are:
- splash
- sheet
- rill
- gully on-site
- stream and channel off-site
Some general points about sediment are:
- Sediment is the name given to the earth particles which have been transported by wind and water.
Sediment is a pollutant.
Sediment can impact on the water quality in streams, lakes, estuaries and harbours.
Sediment in the water can lead to increased erosion of stream banks, etc.
Sediment can bind to toxins in the water trapping them in the system.
High levels of sediment deposition can:
- modify or destroy habitats
- abrade or smother flora and fauna
- destroy food sources
- interrupt life cycles
- damage pumps
- pollute water supplies
- cause flooding
- leave unsightly damage
The recovery time from sediment is measured in years rather than months. Earthworks are a major source of sediment. Sediment yield from earthwork can be up to 1,000 times greater than from rural land. Environment Bay of Plenty is responsible for ensuring the natural and physical resources of the region such as the land, air, water and coastal resources are managed in a sustainable manner under the Resource Management Act 1991. Environment Bay of Plenty has developed a Regional Land Management Plan which outline the rules and regulations regarding earthworks. Under these rules and regulations certain types of activity require Land Use Consents. Land Use Consent forms are available from Environment Bay of Plenty.
| When Is A Land Use Consent Required? |
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Activities requiring Land Use Consents:
- earthworks
- roadworks
- reclamation
- dumping
- any proposed activity within the bed or a lake, river or stream such as the construction of structure
- any activity which results in discharges of stormwater containing sediment into water or onto land
- crossings such as bridges or culverts
If there is any doubt as to whether a Land Use Consent is required contact Environment Bay of Plenty.
| Erosion And Sediment Control Plans |
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Land Use Consent applications should include an Erosion and Sediment Control Plan. The purpose of an Erosion and Sediment Control Plan is to illustrate which erosion and sediment control measures are intended.
The purpose of an Erosion and Sediment Control Plan is to:
- control anticipated erosion
- prevent sediment from leaving the site
Erosion and Sediment Control Plans should include:
- a locality map
- a site plan illustrating:
- the extent of earthworks
- type of potential erosion
- sediment controls
- catchment boundaries
- off-site sources of runoff
- engineering drawings and specifications
- details of vegetative control measures
- contingency plans
- construction schedule/staged activity
- monitoring and maintenance schedules
| Erosion And Sediment Control Practices |
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Some general points on erosion and sediment control practices:
- Keep disturbed areas small.
Stabilise disturbed areas as soon as possible.
Retain existing vegetation where possible.
Revegetate as soon as possible.
Limit time of exposure.
Take the season and weather forecast into account.
Retain sediment on site.
Protect disturbed areas from runoff above site.
Keep on site runoff velocities low by:
- contour drains
- retention of natural vegetation
- provision of buffer strips of vegetation
- low gradients and short slopes
Maintain control measures to ensure ongoing effectiveness.
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