Appendix F - River Control and Drainage Works Programme 5.9.1.2 For the Fairhall and Mill stream channels up to New Renwick Road to maintain clear stable channels and enlarge if proven necessary to carry a one in a 100 year flood. 5.9.2 New Works Required • Enlarge and clear Fairhall and Mill channels downstream of New Renwick Road. 5.10 Riverlands Floodway and Wither Hills Streams (Note: the Wither Hills streams include Mapps, Jacksons, 15 Valley, Sutherlands, Wither and Rifle Range). 5.10.1 Design Intentions 5.10.1.1 To maintain the Riverlands floodway in a clear and easily maintained condition. 5.10.1.2 To achieve a hydraulically efficient channel of Wither Stream through Blenheim by construction and maintenance of a concrete lined channel. 5.10.1.3 To minimise debris and sediment being brought down from Wither Hills streams into the Riverlands channel system. 5.10.2 New Works Required • Completion of concrete lined channel. • Construct debris retards and screens. 5.11 Doctors Creek (up to New Renwick Road) 5.11.1 Design Intentions 5.11.1.1 To upgrade to a consistent standard and maintain a small channelto carry minor floods. 5.11.1.2 To zone as a flood hazard area land flanking Doctors Creek that floods and ponds in major floods. 5.11.2 New Works Required • To enlarge and improve channel downstream of New Renwick Road culvert. 5.12 Pukaka 5.12.1 Design Intentions 5.12.1.1 To strengthen weak stopbanks. 5.12.1.2 To maintain an overflow spillway on the eastern bank that spills into a zoned flood hazard area at times of high Pukaka flood and/or coincidence of high Diversion flood. 5.12.1.3 To investigate options of increasing Pukaka outlet culvert capacity intothe Wairau Diversion. 5.12.1.4 To investigate options of environmental planting on the Pukaka berms. App F - 7