Water And Wastewater

Stormwater Treatment System

Client:Worsley Farm Subdivision
Date:n/a
Location:Christchurch
Value:n/a
Size:n/a
Services Provided:
- Water & Wastewater

CPG's Water and Waste team were engaged to design and implement a stormwater treatment system for a 110 lot hillside subdivision in Christchurch.

The Christchurch Water and Waste team were engaged to design and implement a stormwater treatment system for a 110 lot hillside subdivision in Christchurch. The system needed to over compensate storage in a gully detention basin to allow filling within the floodplain in the lower part of the development. It also had to attenuate stormpeaks to those of pre-development and provide first flush stormwater treatment. Modelling was undertaken and a system provided that would treat all storm durations up to a 50 year storm, with secondary flow paths and spillways to cater for a 200 year storm. The effects were assessed and consenting was successful.

Erosion and sediment control to protect the values of the Cashmere Stream involved the continual shifting of sedimentation ponds, with a zero discharge philosophy. When this could not be achieved due to continual wet weather, use was made of gravel filters, with addition of lime and flocculants.