Sediment Control And Transmission Gully:

STATEMENT BY WELLINGTON REGIONAL COUNCILLOR ROBERT SHAW

The Wellington Regional Council is pursuing improved sediment control techniques for earthworks that affect waterways.

This work has urgency because of the pending works for the Transmission Gully road.

The Porirua City Council and the Wellington Regional Council together funded a major review of the sediment control techniques used through New Zealand.

The establishment of new approaches with contractors is now a priority because of major works that are proceeding in the Region as a part of the implementation of the Regional Land Transport Strategy.

The long-term goal is to set much tighter performance standards in the “sediment and erosion control plans” and have regional councils monitor impacts in a consistent way throughout the country.

The Wellington Regional Council is now using Auckland Regional Council’s guidelines known as Auckland TP90.

This standard still based on 1988 guidelines, but provides more material and advice detailing control techniques.

The new guidelines to be developed for WRC will take into account Wellington’s unique plans and soil conditions.

At present, Transit New Zealand is applying for consents for SH58 upgrade that runs adjacent to the Pauatahanui Inlet.

Because the Pauatahanui catchment is so special ecologically, and because of the potential sediment yields are significant, the WRC has required that flocculation be used when sediment retention ponds fail to meet target efficiencies.

Flocculation is brilliant its been used widely in Auckland 21 sites during the winter Alpurt B1 development, uses inexpensive small systems they look like portable loos, costing $1,750 per unit, efficiencies to 99% even in storms. The critical documents required in the SH58 consents also include contractors’ plans and engineering consultants’ plans with specific requirements.

Once these are set in place there will be a clear structure/chain of command to ensure that the problems do not fall through the gaps and people take responsibility for the issues.

All documents require WRC buy-in through certification, and there is also active involvement of Council staff in a sediment control team to be set up with Transit.

So, in fact, there is a level of shared responsibility and an onus for us all to get the environmental management of that project right roll on Transmission Gully.

For more information:

http://robertshaw.freeyellow.com/index.html

robert.shaw@xtra.co.nz

Telephone 233 0252

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