Marokopa Erosion Protection Structure

Thursday, 01 February 2018

Foreshore protection to mitigate the effects of coastal erosion are costly to construct and have a finite lifespan. The introduction of man-made structures into this dynamic and volatile coastal environment require regular monitoring and eventual replacement.

The Marokopa erosion protection structure was constructed by Waitomo District Council (WDC) to temporarily delay the effects of coastal erosion on the Marokopa Road carriageway. A private unconsented seawall was also erected adjacent to WDC’s consented structure.

Over recent years the unconsented privately erected seawall has begun to fail which has attributed to undermining the foundation of the WDC structure and created a health and safety risk.   Emergency works were required in December 2016 to mitigate the risk to public safety. 

Engineering advice was sought. The site was investigated to assess the options and provide a structural design plan to reduce the risk of any further failure to the WDC structure.   Consultation with the Regional Council and local Iwi, which included obtaining an archaeological assessment, was also undertaken to help inform the process.    

Initially, the best outcome looked to be achieved by dismantling the private wall and adding rock armouring to extend the structure for an extra 20 metres north. However, estimated construction and professional services costs, the uncertainty of success and the high risk to both recorded and unrecorded archaeological sites meant that in November 2017 WDC decided not progress with the project any further.

WDC intends to continue with regular monitoring and maintenance of the erosion protection structure at Marokopa as to the resource consent requirements for that structure.