Installation (chute formation)
1. 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.
2. Ensure all necessary soil testing (e.g. soil pH, nutrient levels) and analysis has been completed, and required soil adjustments performed prior to planting.
3. Clear the location for the chute clearing only what is needed to provide access for personnel and equipment for installation.
4. Remove roots, stumps, and other debris and dispose of them properly.
5. Construct the subgrade to the elevations shown on the plans. Remove all unsuitable material and replace with stable material to achieve the desired foundations.
6. If the chute is temporary, then compact the subgrade to a firm consistency. If the chute is intended to be permanent, then compact and finish the subgrade as specified within the design plans.  
7. Avoid compacting the subgrade to a condition that would prevent the turf from bonding with the subgrade.
8. Ensure the sides of the chute are no steeper than a 1.5:1 (H:V) slope.
9. Ensure the completed chute has sufficient deep along its full length.
10. Ensure the chute is straight from its crest to the toe of the chute.
11. On fill slopes, ensure that the soil is adequately compacted for a width of at least one metre each side of the chute to minimise the risk of soil erosion, otherwise protect the soil with suitable scour protection measures such as turf or erosion control mats.
12. Place and secure the turf as directed.
13. Install an appropriate outlet structure (energy dissipater) at the base of the chute (refer to separate specifications).
14. Ensure water leaving the chute and the outlet structure will flow freely without causing undesirable ponding or scour.
15. Appropriately stabilise all disturbed areas immediately after construction.

Additional specifications for the installation of the mattresses:
Installation procedures should be provided by the manufacturer or distributor of the product.  A typical installation procedure is described below, but should be confirmed with the product manufacturer or distributor.

Materials
* Rock infill: hard, angular, durable, weather resistant and evenly graded with 50% by weight larger than the specified nominal rock size. The diameter of the largest rock size should be no larger than 1.5 times the nominal rock size.
* Geotextile fabric: heavy-duty, needle-punched, non-woven filter cloth, minimum bidim A24 or equivalent.
Installation
1. Refer to approved plans for location, extent and installation details.  If there are questions or problems with the location, extent, or method of installation contact the engineer or responsible on-site officer for assistance.
2. Mattresses of different thicknesses should be stored on-site in separate piles and clearly labelled.
3. Clear the proposed channel area of trees, stumps, roots, loose rock, and other objectionable materials.
4. Excavate the treatment area to the lines and grades as shown on the plans.  Over-cut the area to a depth equal to the specified mattress thickness such that the finished surface will be at the elevation of the surrounding land.
5. Place filter fabric directly on the prepared foundation.  If more than one sheet of filter cloth is required to over the area, overlap the edge of each sheet at least 300mm and place anchor pins at minimum one metre spacing along the overlap.
6. Ensure the filter cloth is protected from punching or tearing during installation of the mattresses.  Repair any damage by removing the rock and placing with another piece of filter cloth over the damaged area overlapping the existing fabric a minimum of 300mm.
7. Flatten out each mattress on a hard, flat surface, and stamp out any unnecessary creases.  Edge creases will need to be stamped into the bottom of the 2nd and 4th internal diaphragms.
8. Ensure that each diaphragm is vertical and the correct height.  Fold the sides and ends of the mattress to meet the top of the diaphragms.  Fold the side panel flaps to lie adjacent to the diaphragms.  Tack temporarily either by using short lengths of binding wire, or alternatively by twisting the top diaphragm wire over the flap selvedge wire.
9. The ends of the diaphragms must now be permanently laced to the sides of the mattress.  At the four corners, bend the projected lengths of the end panels to overlap the sides, and lace up with binding wire.
10. When the mattress is placed over a geotextile, care must be taken to ensure that projecting ends of wire are bent upwards to avoid puncturing or tearing the cloth.  Geotextile should be placed according to specifications.
11. Carry the wired-up mattress to its final position, and wire it securely to the adjacent mattresses.  Mattresses should be placed and wired together empty as it is difficult to wire mattresses together when both are full of stone.
12. On slopes, the mattress should generally be laid with the diaphragm across the slope rather than up and down the slope.  On chute and stream beds, the mattress should generally be laid with the diaphragm at right angles to the main direction of water flow.
13. All hand wiring must be done as a continuous lacing operation.  Begin wiring by securing the binding wire to the corner of the panels to be joined by looping it through and twisting it together.  Then lace with single loops and double loops in turn at 100mm intervals.  Finally poke the loose end inside the mattress.  Tightness of the mesh and wiring is essential at all times.
14. Place the fill material, by hand or mechanically, in the compartments, starting at the bottom if on a slope.  The fill should be a hard, durable stone, in size between 80mm and two-thirds the thickness of the mattress, but generally no greater than 200mm.
15. Filling can be done unit by unit, but several units should be ready for filling at any one time.
16. For units with PVC coated wire mesh, particular care shall be taken to ensure that sharp edges of quarry stone are not placed against the mesh in order to avoid causing unnecessary abrasion.
17. Slightly overfill each mattress to allow for settlement.  Tack the lid to the corners of the mattress, and then securely wire it to the tops of the sides, ends and diaphragms, using alternate single and double loops as specified above.
18. With more than one mattress filled, the edges of adjacent lids can be wired down in the same operation, saving both time and binding wire.
19. When the mattress is laid on a slope steeper than 1.5:1(H:V), it should be secured by star pickets or hardwood pegs driven into the ground just inside the upper end panel at two (2) metre centres or as necessary.
20. On soft or sandy slopes, pegs can be used to hold the mattress in position during filling.
21. Mattresses can be shortened where necessary, by cutting along the fold at the top of a diaphragm and removing the bottom spiral connections.
22. Always consult manufacturer's specifications and assembly instructions before modifying the shape of the mattress or wiring deformed mattress shapes.
23. Immediately upon completion of the channel, vegetate all disturbed areas or otherwise protect them against soil erosion.
24. Where specified, fill all voids with soil and vegetate in accordance with the approved plan.

Maintenance
1. During the construction period, inspect all chutes prior to forecast rainfall, daily during extended periods of rainfall, after significant runoff producing storm events, or otherwise on a weekly basis. Make repairs as necessary.
2. Check for soil scour adjacent the chute. Investigate the cause of any scour, and repair as necessary.
3. Ensure sediment is not partially blocking flow entry into the chute. Where necessary, remove any deposited material to allow free drainage.
4. Dispose of any sediment in a manner that will not create an erosion or pollution hazard.
5. When making repairs, always restore the chute to its original configuration unless an amended layout is required.

Removal
1. When the soil disturbance above the chute is finished and the area is stabilised, the chute and any associated flow diversion banks should be removed, unless it is to remain as a permanent drainage feature.
2. Dispose of any materials, sediment or earth in a manner that will not create an erosion or pollution hazard.
3. Grade the area in preparation for stabilisation, then stabilise the area as specified in the approved plan.