132 5 Stockpiling of ore or potentially acid forming waste rock shall occur only at sites specifically prepared for that purpose. Any area to be used for this purpose shall be constructed from or lined with at least 600mm of natural or non acid forming materials with a permeability of less than or equal to 1x10-8 m/s, or alternatively a synthetic liner with equivalent or better performance, approved by the Waikato Regional Council. In situ soils may be used for this purpose if the Consent Holder can demonstrate to the Waikato Regional Council’s satisfaction that the protection provided is equivalent to the liner specification detailed above. In addition to the provisions of Condition 4(a) and 4(b) above, PAF stockpile site preparation shall include: a. Grading of the proposed stockpile site and construction of stockpile drains around the site perimeter to divert stockpile run-off and leachate to a collection pond or ponds (from which collected water can be pumped to the water treatment plant prior to discharge to the Ohinemuri River); and b. Placement of selected, coarse waste rock as the initial layer on the low-permeability layer of the stockpile footprint to act as a leachate drainage layer; c. If an alternative synthetic liner is used in preference to an earth liner, the liner shall be covered with a protection layer consisting of soil that is placed and compacted to a minimum thickness of 400mm. 6 Drains constructed for the purposes of conveying run-off and leachate from the PAF stockpile(s) to the collection pond(s) and the Water Treatment Plant shall be lined by a method agreed to by the Waikato Regional Council and detailed in the Water Management Plan prepared pursuant to Conditions G49 – G51 of Schedule Two – General Conditions. 7 The Consent Holder shall ensure that the collection pond(s) referred to in Condition 5 above is designed and constructed from materials that provide secure long term containment including: a. A low-permeability liner forming the base and sides of the pond(s) that achieve the same or better standard to that required of the PAF stockpile liner as detailed in Condition 5 above, or alternatively a synthetic liner with equivalent or better performance, approved by the Waikato Regional Council; b. A minimum water storage capacity equivalent to the volume of runoff generated from within its catchment during a 10-year return period, 72-hour duration, design storm; c. A pump system capable of pumping all stormwater reporting to the collection pond during rainfall events less than or equal to the above design storm to the water treatment plant for treatment; and
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