4.2.19 Gradient Control Structures
22.214.171.124 Permitted Activity Rule – Gradient Control Structures*
- Unless controlled by Rule 126.96.36.199 the use, erection, reconstruction, placement, alteration or extension of any gradient control structure, and associated bed disturbance, in, on, under or over the bed of a river or lake, and
- Necessary deposition of any construction material, and
- Any discharge of sediment associated with construction activities;
are permitted activities subject to the following conditions:
- The structure shall not be located in, on, under or over any river bed exceeding 10 metres in width.
- Any maintenance work undertaken on the structure shall not exceed a total of 24 hours in any two-month period.
- Any such gradient control structure shall be designed so that a two percent annual exceedance probability (1 in 50 year) flood event shall not cause any increase in upstream water levels on neighbouring properties.
- The construction works shall comply with the suspended solids discharge standards as set out in Section 4.2.21.
- All equipment and surplus construction materials shall be removed from the river or lake bed and the floodplain on the completion of that activity.
- No contaminants (including, but not limited to, oil, hydraulic fluids, petrol, diesel, other fuels, paint or solvents, but excluding sediment) shall be discharged to water from the activity.
- The structure shall provide for the safe passage of fish both upstream and downstream.
- The structure shall not be constructed in a water body identified as Natural State in the Water Management Class Maps in this Plan.
- The structure shall be maintained in a structurally sound condition at all times.
- The activity shall not disturb any archaeological site or waahi tapu as identified at the date of notification of this Plan, in any district plan, in the NZ Archaeological Association’s Site Recording Scheme, or by the Historic Places Trust except where Historic Places Trust approval has been obtained.
- In the event of any waahi tapu that is not subject to condition j) being identified by the Waikato Regional Council to the person undertaking the use, erection, reconstruction, placement, extension or alteration, the activity shall cease insofar as it may affect the waahi tapu. The activity shall not be recommenced without the approval of the Waikato Regional Council.
- Any erosion occurring as a result of the structure shall be remedied as soon as practicable.
- The structure shall be constructed of rock or clean concrete placed such that there is no visible steel in the finished work.
- This rule shall not apply to activities located in, on, under or over the bed of a river or lake that is a Significant Geothermal Feature.
- The owner of the structure shall inform the Waikato Regional Council in writing of the location of the structure at least 10 working days prior to commencing construction.
- The use, erection, reconstruction, placement, alteration or extension of a gradient control structure in, on, under or over the bed of a river that does not comply with Rule 188.8.131.52 is a discretionary activity in accordance with Rule 184.108.40.206.
- Where a waahi tapu site is identified whilst undertaking the activity, the process that Waikato Regional Council will follow in order to implement condition k) is set out in Section 220.127.116.11 of this Plan.
- Where a structure or activity is to be located in, on, under or over the bed of a water body that is Significant Geothermal Feature, Rules 18.104.22.168 to 22.214.171.124 shall apply. Significant Geothermal Features are defined in the Glossary, and in Development and Limited Development Geothermal Systems, identified on maps in Section 7.10 of this Plan.
Explanation and Principal Reasons for Adopting Method 126.96.36.199
The use, erection, reconstruction, placement, alteration or extension of gradient control structures are unlikely to have any significant adverse effects. They provide some positive effects by preventing scour and providing a stable river bed and bank. The reason for restricting the structure to points of a river bed not exceeding 10 metres wide is that rivers are unlikely to be navigable at this width.