Materials
* Primary core rock: well graded, hard, angular, erosion resistant rock, with mean size as specified in the approved plan, but not less than 225mm, or greater than 350mm.
* Armour rock: well graded, hard, angular, erosion resistant rock, with mean size as specified in the approved plan, but not less than 225mm.
* Aggregate filter: 15 to 25mm clean aggregate.
* Geotextile filter fabric: heavy-duty non-woven, needle-punched filter fabric, minimum 'bidim' A34 or equivalent.

Installation
1. Prior to commencing any works, obtain all necessary approvals and permits required to conduct the necessary works including permits for the disturbance of riparian and aquatic vegetation, and the construction of all permanent or temporary instream barriers and instream sediment control measures.
2. Refer to approved plans for location and construction details. If there are questions or problems with the location, or method of installation, contact the engineer or responsible on-site officer for assistance.
3. If there is flow within the watercourse or drainage channel at the time of construction of the rock filter dam, then install appropriate downstream sediment control devices and/or flow diversion systems prior to construction of the dam. Such measures should only be installed if considered appropriate for the local conditions, and only if their installation is judged to provide a net overall environmental benefit.
4. To the maximum degree practicable, construction activities and equipment must not operate within open flowing waters.
5. Clear the location for the dam; clearing only what is needed to provide access and to install the dam.
6. Remove any cleared organic matter and debris from the disturbance area and dispose of it properly. Do not use organic matter or debris to build the rock filter dam.
7. To assist in the eventual removal of all materials used in the construction of the rock filter dam, a protective layer of geotextile fabric (preferably in the form of a single sheet) should be placed over the channel area and dam abutments prior to installation of the dam. If more than one sheet of fabric is required, overlap the fabric by at least 600mm.
8. If dispersible, highly unstable, or highly erosive soils are exposed, then priority must be given to the prompt stabilisation of all such areas.
9. Place the core rock for the rock filter dam. Ensure the upstream face is 2:1(H:V) or flatter, and the downstream face is 3:1(H:V) or flatter.
10. The rock material used to form the dam should be well-graded mixture of rock with a minimum size of 225mm and a maximum of 350mm (excluding armour rock). The rock may be machine placed with the smaller rocks worked into the voids of the larger rocks.
11. Small rock filter dams (< 1m high) including should be constructed in a slightly curved profile (in plan view) pointing upstream. The centre of the dam's crest should be slightly lower (typically 200mm) than the outer abutments to promote initial overtopping at or near the centre of the channel.
12. Where necessary, extend the rock protection downstream past the toe of the formed embankment until stable conditions are reached, or a distance equal to the height of the dam, whichever is the greater.
13. Install the specified filter (aggregate and/or filter cloth) on the upstream face of the rock filter dam.
14. If filter cloth is used, then:
(i) extend the fabric over the crest of the rock filter dam into the spillway chute;
(ii) consider the placement of several layers of overlapping fabric, thus allowing each layer to be removed individually once the fabric becomes blocked with sediment.
15. Take all necessary measure to minimise the safety risk caused by the structure.

Maintenance
1. Inspect the rock filter dam prior to forecast rainfall, daily during extended periods of rainfall, after runoff producing rainfall, or otherwise on a weekly basis.
2. Ideally, rock filter dams should discharge (from full) over no less than 8 hours. If drainage is too rapid, then additional filter aggregate may be required to achieve optimum hydraulic performance.
3. If flow through the structure is reduced to an unacceptable level, the upstream filter medium (aggregate or filter cloth) should be removed and replaced.
4. If a greater degree of water treatment (filtration) is required, extra geotextile filter fabric should be placed over the upstream face of the structure.
5. Check the structure and downstream channel banks for damage from overtopping flows. Make repairs as necessary.
6. Immediately replace any rock displaced from the dam.
7. Remove sediment and restore original sediment storage volume when collected sediment exceeds 10% of the specified storage volume.
8. Dispose of sediment and debris in a manner that will not create an erosion or pollution hazard.

Removal
1. The rock filter dam should be removed as soon as possible after they are no longer needed.
2. If there is flow within the watercourse or drainage channel at the time of removal of the rock filter dam, then install appropriate instream sediment control devices and/or flow diversion systems prior to its removal. Such measures should only be installed if considered appropriate for the local conditions, and only if their installation is judged to provide a net overall environmental benefit.
3. All settled sediment upstream should be removed prior to the dam's removal. Dispose of the sediment in a manner that will not create an erosion or pollution hazard.
4. Remove all materials used to form the embankment including the geotextile filter cloth and dispose of in a manner that will not create an erosion or pollution hazard.
5. Restore the watercourse channel to its original cross-section, and smooth and appropriately stabilise and/or revegetate all disturbed areas.