Reducing risk of water contamination in Christchurch

July 7, 2021
CCC Wellhead Upgrade Pre-Condition Surveys

The brief

Prendos was engaged to complete pre-development condition surveys, in order to reduce the risk of contamination from floodwater to 27 drinking-water wells. And in doing so, establish the extent of existing damage to properties adjacent to the proposed drilling sites prior to work commencing.

 

The solution

To achieve this, well casings at each site had to be extended above ground and over-drilled to depths ranging from 6m to 20m, depending on the depth of the confining layer. This was followed by the filling of annuluses with a stabilised bentonite grout mix; and valve assembly arranged horizontally over a concrete plinth.

We carried out pre-development condition surveys of all relevant properties, consisting of more than 200 primarily residential properties (apartments and detached houses), as well as some commercial buildings.

Close liaison with property owners was required to obtain access at mutually convenient times. No contact details were available for most residents, so access had to be arranged at mutually convenient times by pre-notification letters and door-knocking.

 

The outcome

Through clear, open and respectful communication with all property owners and tenants, Prendos surveyors compiled the large number of condition surveys within the set timeframe. Using three in-house surveyors proved very effective as it ensured uniformity across all reports. This allowed the main contractor to get on with the work of upgrading the wellheads with minimal issues.

What’s more, careful co-ordination and quick mobilisation of our survey teams allowed programmed works to be completed on time, despite very tight timeframes and short lead-in times.

 

Client: Seipp Construction
Location: Christchurch
Services: Building surveying – pre-development condition surveys
Prendos contact: Andrew Maxon – Senior Building Surveyor | andrew.m@prendos.co.nz