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Wigram East Basin improvements nearly finished

Reduced flooding, cleaner water and more walking tracks are on the cards with the completion of work to improve the Wigram East Basin in Canterbury Agricultural Park. Check out the full story on Newsline.

Project quick facts:

• The project was fast tracked to provide critical flood mitigation and works were scheduled to allow for the material excavated to be used in the construction of Nga Puna Wai sports hub. This saved money, and reduced the impact on the environment and our neighbours by vastly reducing the number of truck movements.
• In a 100-year storm the area will store around 590 million litres of water – the equivalent of more than 236 Olympic size pools.
• The area is a ‘Site of Ecological Significance’. It hosts many protected breeding birds in the spring and summer, such as the grey duck, Black Billed Gulls, Australasian Bittern, Red-billed Gull, Pied Stilt and Black Cormorant. This meant we had to be very careful with the timing of works so as not to disturb their breeding. We are also extending this habitat through the wetland and other plantings.
• Pukeko have presented a challenge on site tearing up our newly planted native plants.
• The project has added around 1km of walking tracks and routed them away from the most productive bird breeding sites to help separate dogs from breeding birds.
• The basin has already helped to reduce flooding – partially filling on 1 June to reduce flood flows in the river downstream.

Upper to mid-Ōpāwaho/Heathcote bank stabilisation

The final section of planned bank works in the upper to mid-Ōpāwaho/Heathcote was completed at the end of May, with contractors working hard to get matting down ahead of the forecast rain.

Stage 2 of the project has progressed well, helped along by lessons from Stage 1 and much less rain in early 2019 than the same period last year. Contractors will continue to monitor the new works and maintain landscape planting.
The river will undoubtedly find new unstable sections of bank to erode and the completed works won’t stop this, but they will reduce the amount of reactive repairs required. We also now have good working knowledge of construction methods which will help with future work.
Landscape planting, rock edging and eel hides also help to provide new habitats and increase ecological diversity along the river corridor.

Richardson Terrace Pump Station and Storm Filter all go

The brand new pump station near the corner of Richardson Terrace and Ferry Road was called into service in the small hours of 1 June with the heavy rainfall. The main pumps help to lift flood water out of the Bells Creek catchment into the Ōpāwaho/Heathcote River. Within the same facility, the new stormfilter - Australasia’s largest - also treats most stormwater before it flows into the Heathcote. During very large storms, such as later that weekend, water flow bypasses the filters.
The pump station and storm filter are the final stages of the overall Bells Creek flood remediation works which include Edmonds Park stormwater basin and Te Oranga Waikura Urban Forest and Stormwater Basin on Ferry Road.

The pump station is shown in the image above, and below images show the outfall into the Heathcote, and the stormwater filtration system.

Lower Ōpāwaho/Heathcote dredging underway again

Dredging will soon be underway again in the Ōpāwaho/Heathcote following the end of the inanga spawning season.

The break in river works has allowed for landscaping to be done along the Stage 1 works between Radley Street and the Woolston Barrage, as well as much needed maintenance of dredging machinery. Check out the planting plan for Stage 2 along Clarendon and Richardson Terraces here, under 'Heathcote River'.
Over the next few months the reach between Sheldon Street and Radley Street will be dredged, followed by areas around Brougham Street. Later in 2019 work will begin on the next stages upstream of Opawa Road.
The new footpath through Laura Kent Reserve is now open and thanks to the generous planting efforts of volunteers last month, as well as work from our contractor, the area is home to hundreds of new native plants and many trees.
Connal Reserve on the true left of the river (opposite Radley Park) will remain closed while the grass establishes, but should be open to the public by spring.

Curletts Stormwater Basin progressing well

Earthworks are now complete for The Curletts Stormwater Basin. It will provide approximately 130,000m3 of flood storage to help reduce flood risk to properties around the upper and mid Ōpāwaho/Heathcote River. It will also provide treatment to improve the water quality downstream in Curletts Stream and Ōpāwaho/Heathcote River.

Now that the earthworks are done, most areas have been grassed and permanent fencing installed, work on the bund structures is nearly complete. The main flood mitigation gate is due to be installed in August, before the final site tidy.

Planting of the basin with wetland plants, shrubs and trees is planned to be completed by spring. Once planting is down, the site will be opened to the public as a recreational space with formed gravel and grass tracks around the basins for pedestrian and cycle access from Mokihi Gardens to Annex Road.