Annex 7 - Engineering Specifications

  1.3. Footprint of reef patches to consider construction practicality and tolerances. This includes:
    1.3.1.        Allowance for a minimum distance from MHWS sufficient to allow for placement of
                  design rock grading.
    1.3.2.        Minimum distance of 1m from seaward extent to allow for construction tolerances in
            deeper water.
  1.4. Crest width to be minimum 1m in any direction. Larger crest widths (up to nominal 10m) are
        more desirable as they provide a larger area for oyster growth.
  1.5. Access space between reef patches to nominally be 1m - 4m although larger spaces may be
        desirable depending on site configuration or expected sediment transport or siltation.
  1.6. Final layout of reef patches to be determined by certifying coastal engineer prior to
        construction and take into consideration local bathymetry, geometry of Restoration
        Footprint, adjacent land uses, presence of erosion, existing infrastructure, wave action, water
        flows, sediment type, expectation of siltation and any other relevant factors.


2. MATERIALS

  2.1. Rock
    2.1.1.        Grading to be stable for individual locations and provide voids, rugosity and habitat
                  complexity suitable for habitat growth as per design reef patches in drawings.
                  - Phase I sites. Rock grading to be 150 - 500mm diameter with 50% over 300mm.
                  - Phase II sites. Rock grading for individual sites to be determined by coastal engineer
                  for stability and suitability prior to construction
                  - Individual larger rocks may add to rugosity and may be incorporated provided that it
                  fits within the profile of the reef patch and achieves good interlocking.
    2.1.2.        Rock to be igneous or metamorphic rock suitable for use in the marine environment.
                  Rock to be sound, hard, durable and angular. Rock to be clean and free of topsoil and
                  organic matter.
    2.1.4         Rock characteristics to be in accordance with the Table 2.


Table 2: Rock characteristics

 Parameter                                        Standard              Requirement
 Density                                          AS1141.6.1            >2600kg/m3
 Water absorption                                 AS1141.6.1            <1.5%
 Abrasion resistance (Los Angeles)                AS1141.6.23           <25%
 Wet Strength                                     AS1141.6.22           >170kN
 Salt Attack (Sodium Sulphate Soundness)          AS1141.6.24           <6%

  2.2. Cured Oyster Shell