Materials
* Aggregate: 15 to 25mm crushed rock.
* Mesh: wire mesh with 6 to 12mm open grid.

Installation
1. Refer to approved plans for location and dimensional details. If there are questions or problems with the location, dimensions or method of installation contact the engineer or responsible on-site officer for assistance.
2. Ensure that the installation of the sediment trap will not cause undesirable safety or flooding issues.
3. Clear the area of all debris that might hinder excavation and disposal of spoil.
4. Excavate the settlement pool around the storm inlet to obtain the required settling volume/area as specified on the approved plans.
5. Ensure the maximum depth is 600mm measured to the crest of the inlet structure, and batter slopes are no steeper than 2:1(H:V).
6. Grade the approach to the stormwater inlet uniformly to minimise scour cause by inflow water.
7. Drill or otherwise establish drainage holes at various levels in the inlet structure to allow free draining of the excavated pool. Cover the drainage holes with weir mesh then cover the mesh with a stable batter of filter aggregate.
8. Where directed, establish a flow control bund to control the passage of bypass flows.
9. Take all necessary measure to minimise the safety risk caused by the structure and to prevent unsafe entry into the stormwater inlet.

Maintenance
1. Inspect the sediment trap after each runoff producing rainfall event and make repairs as needed to the structure.
2. Stabilise flow entry points as required.
3. Remove sediment if over 1/3 of the storage volume has been lost, or as necessary to provide adequate storage volume for subsequent storms.
4. Dispose of sediment in a suitable manner that will not cause an erosion or pollution hazard.
5. Replace the filter aggregate when water fails to adequately drain from the sediment pool or when silt is observed passing through the drainage holes.

Removal
1. When the up-slope drainage area has been stabilised, seal the drainage holes, fill the basin with stable soil to the specified grade and elevation, then compact and stabilise/revegetate as required.