86 • Assist the regrowth or replenishment of ecologically sourced swamp maire. • Ensure that the hydrological (surface and groundwater) connection and hydrological replenishment is maintained. • Protection through covenant or similar mechanism in perpetuity. 14.4.4 Culverts and fish passage 14.4.4.1 Culverts Culverts will be installed at stream or overland flow path crossings. BECA (2022) states that culverts will typically be sized to accommodate the 20-yr storm flow. However, key culverts will be sized to the 100-year return event, where build-up of headwater and overland flow would have detrimental effects on infrastructure (e.g., inundation of the SFA, access roads and adjacent property). Erosion protection devices will be installed where required. Typical scour protection and flow energy dissipation devices are discussed in BECA (2022). Culverts will either be concrete pipe or box culverts, subject to detailed design. Piping and culverts relating to the WRS have not been included and are dealt with under the reclamation of tributary 2. 14.4.4.2 Fish passage requirements for culverts Regulations 62 and 63 of the NESF set out the information that is required to be collected and supplied to the Waikato Regional Council. That extent of detail is not provided here but the key culverts and their fish passage requirements are provided in Table 26 (from BECA 2022). Fish passage design should follow the guidance provided in the Fish Passage Guidelines (NIWA 2018), noting that these guidelines are for structures up to 4 m in length25. Table 26:. Key Culverts at Willows Farm SFA and fish passage requirements. Excludes culverts to be installed at WRS and Mine access road. Culvert information from BECA (2022). Locations of culverts shown in BECA (2022). Culvert ID Design Storm AEP Approximate Length (m) Minimum Size (m) Fish passage requirements SW-C2A 1% 50 1.5 Passage for climbing fish required. SW-C3A 1% 27 1.2 Passage for climbing fish required. SW-C4A 1% 10 1.2 No fish passage requirements. Feature is an ephemeral flow path. SW-C4B 1% 15 1.2 No fish passage requirements. Feature is an ephemeral flow path. For completeness we note that although culverts will be placed on the clean water channels of the WRS, no culverts will be placed on the lower tributary 2 and there is no requirement for fish passage during WRS construction and operations. We understand that at rehabilitation of tributary 2 the nine culvert crossings associated with the clean water channels will be removed. 25 The fish passage guidelines focus on the legislative requirements for providing fish passage and provide the necessary information to allow infrastructure designers to integrate the needs of fish into the design process.
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