Puhinui Stream Restoration Project

Puhinui Stream Restoration Project. Authors Tony Miller GHD Yasenko Krpo Manukau City Council WSUD Conference , Brisbane, 2000.

Upper Puhinui | Wiri Pond | Everglade Pond/SH20 | Public Walkway

Upper Puhinui

Puhinui Stream Restoration Project
Click to enlarge	Commenced 1999 and is ongoing Consists of following projects: Upper Puhinui Project Wiri Pond Project Everglade Pond and SH20 Projects Public Walkway, riparian planting and removal of barriers to fish passage Background Puhinui Stream located in Manukau City 2000ha catchment 8km long Discharges next into Manukau Harbour next to Auckland Airport

Upper Puhinui Stream Project
	Catchment Study and Management Plan 1999 Modelling of stream 2 culvert embankments hazard Solution - Culverts & intakes upgraded Runoff from new 60 ha residential area discharges to stream without detention or treatment Solution - 2 new water quality ponds constructed

Upper Puhinui Stream ProjectEmbankment hazard
	Embankment hazard Mill Road 12m high embankment 1200mm culvert Residential catchment downstream New intake structure Upgraded cutoff Future detention area

	Embankment hazard Totara Park 6m high embankment Twin 1050mm culvert Residential catchment downstream New intake structure New embankment with full cutoff Detention dam

Upper Puhinui Stream ProjectHospice Pond & Pond 2000

	Background Catchment of 38 ha & 21 ha Ponds built ‘off line’ Designed for water quality & detention 75% TSS removal 25mm design storm and empty over 24 hours System of swales and pipes collects from 5 separate subcatchments Project won an World Environment Day award Issues Design for 1500m3 sediment over 10 years Sediment forebay operational 18 months. Collected 300mm sediment. First Clean out at 24 months Pond has 6m high embankment (3m below ground level) Project cost NZ$1.0m WQ cost is approx NZ$12,000 / ha to service existing residential catchment.

Wiri Pond Project

	Issues ‘On Line Pond’ Built in 1960’s 1050ha catchment No Maintenance 7000m3 sediment accumulated Ducks “walking on water” Sediment tested for contaminants Low turbidity Dredging trial undertaken

Wiri Pond Project Redesign

	Redesign Off line’ option chosen 2 new sediment forebays designed Bypass to take 1 in 1 month storm Costs to desilt = $NZ12/tonne Project cost NZ$1.2m

Wiri Pond Project New Forebays



Wiri Pond Project Flood Conditions



Wiri Pond Project Pond Cleanup



Wiri Pond Project Mucking Out

SH20 – SH1 Motorway Project

Click to enlarge	Motorway Project New NZ$120m 5km motorway in urban environment All stormwater directed to one of 7 new storm water quality ponds 5 of 7 ponds in joint funding arrangement Contributing catchment 50ha M’way and 364ha of residential & commercial Everglade Detention Dam project (+80ha) Key design features Ponds designed for 75% TSS removal 25mm design storm stored & released over 24 hrs Revised TP10 target storm 37.5mm Pond treatment volume 5,000 to 20,000m3 Most have sediment forebays Average depth is 1.5m Low flow outlets drowned – hydrocarbons & floatables

Barriers To Fish Passage