Chapter 31 - Town Commercial Zone 31.1.3.2 Exception Residential dwelling units associated with any permitted activity shall be permitted where the siting and construction of any dwelling is designed to reduce the exposure of the occupants to external noise. Such dwellings shall be constructed to achieve an indoor design sound level of 53 dBA L max in any habitable room based on a designed sound level of 75 dBA L max at the boundary of the site, or 10 metres from the dwelling whichever is the closer to the dwelling. The indoor design level shall be achieved with windows and doors open unless adequate alternative ventilation means is provided. 31.1.4 Land Disturbance 31.1.4.1 Land Disturbance General Any land disturbance activity which meets the conditions below is a Permitted Activity. 31.1.4.1.1 Conditions a) Any increase in the concentration of suspended sediment shall not be more than 20% as measured by the ‘black disk’ method, notwithstanding that the concentration of suspended sediment in run-off water shall not exceed 200 grams/cubic metre at any point of discharge to any receiving water. The effects on the receiving water are to be measured at a distance downstream of two widths of the receiving watercourse or 50 metres, whichever is the lesser; b) No woody material of greater than 100mm diameter shall be left in any permanently flowing river, lake, wetland or sea as a result of a land disturbance operation; or c) All land disturbance sites are to be stable when subject to a storm event of 10% probability or less. 31.1.4.1.2 Exception Except any land disturbance activity in an area identified as a hazard area that is required for the purposes of constructing or providing access to any structure requiring a building permit under the Building Act 1991, shall not be a Discretionary Activity, with no restriction on the exercise of Council’s discretion. 31.1.4.2 Excavation and Filling 31.1.4.2.1 Conditions a) The maximum volume for either excavation or filling shall not exceed 20m³in any continuous ten year period; b) The gradient of any side cut excavation must not exceed an average of 9.5 (1:6) and must not exceed 11.3 (1:5) along any length of more than 20 metres; c) Stormwater controls, watertable cut-offs, and culverts are to be installed to ensure that erosion does not occur on the inside edge of the cut. No culvert size less than 300mm may be used to drain any side-cut excavation; 31 - 5