60 5 The Willows Rock Stack shall be constructed in general accordance with the design outlined in the consent application, in particular, the following design document prepared by WSP Golder which was included in Part H of the application documents “Oceana Gold (New Zealand) Limited Waihi North Project; Wharekirauponga Underground Mine – Willows Rock Stack and Surface Facilities Geotechnical Assessment, Submitted by WSP New Zealand Limited” (the WSP Design Report) 6 Clean water drains designed to accommodate, at minimum, 1 in 10 year storm flow with 300 mm of freeboard shall be installed and maintained around the footprint of the Willows Rock Stack, WRS Toe Seepage Pond and Mine Access Road to divert clean surface runoff and intercepted groundwater around the footprint of those activities. 7 Diversion drains shall be installed and maintained to collect runoff from the Willows Rock Stack, WRS Toe Seepage Pond and Mine Access Road and divert it to the Main Collection Pond authorised by Resource Consent [insert consent numbers authorising Main Collection Pond]. 8 The footprint of the Willows Rock Stack shall be stripped of topsoil, subsoil and other weak material such that it is underlain by materials which: a. Have no acid forming potential; and b. Have a permeability of no greater than 1x10-8m/s 9 A rockfill underdrainage system shall be installed and maintained in the gully beneath Willows Rock Stack to collect contaminated seepage from waste rock, to minimise the release of seepage to ground and convey it to the Main Collection Pond. 10 The Consent Holder shall ensure that the WRS Toe Seepage Pond is fully lined with a 1.5 mm HDPE (or other similar synthetic liner approved by the Waikato Regional Council). 11 The Consent Holder shall supply at least the following documentation to the Waikato Regional Council prior to commencement of the construction works authorised by this consent: a. Detailed Design Report b. Specification c. Drawings d. Construction Monitoring Inspection Schedule All subsequent amendments to the design shall be supplied to the Waikato Regional Council prior to implementation.
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