Holding back the sea: achieving zero erosion on coastal sites

For people whose homes or buildings are located on coastal sites, they know all too well the disastrous impacts of rising seas and tides - most confronting perhaps in New Zealand’s frequent storms. Without adequate protection, waves pummeling the shores can cause significant erosion - resulting in property owners watching their land dropping into the sea.  

For property owners, powerless to stop their land slipping away, the forecast of a storm can raise the possibility of a catastrophic event. The solution though is simple, Auckland Stonemasons’ Len Lavas says. Len comes from a long line of stonemasons - a family whose origins lie in Croatia, a country world-renowned for the ancient art of stonemasonry.

It’s from their forefathers that Len and his brother Jim learnt the art, gaining knowledge passed down through the generations; knowledge Len passes on every day to his ever-expanding team in Auckland. It’s also knowledge that has the capacity to change the future for coastal sites, and has been doing so in New Zealand since the 1930s in the form of artfully constructed sea walls.

Most of us will be familiar with the work of Auckland Stonemasons in a civil capacity - the Tamaki Drive sea wall, the Devonport sea wall, the Point Chevalier sea wall and countless projects around the country including the Whitianga, Pauanui and Marsden Cove waterways.  However, it’s not just civil settings where seawalls are a key element of holding back the sea; they’re often the best - and only - solution for private land owners too, Len says.

A recent project Len and his team completed at Sunkist Bay in Beachlands, Auckland comprised three sea walls around the perimeter of three separate privately-owned properties. “This is one of the worst-known areas in Auckland for erosion. About two years ago, they had some large storms and a lot of resulting damage,” Auckland Stonemasons’ Len Lavas says.

“In this particular bay, we had previously built the stone sea wall on the public beach at Sunkist Bay and that wall received no damage in these storms. A separate boulder wall that was also built in the bay was torn to pieces in the storm and the resulting damage was significant.  “During those storms, some people in this area who did not have seawalls lost around one-tenth of their sections to slips.”

The resulting three sea walls built by the Auckland Stonemasons team are designed to protect the land from future storms and rising seas - walls that are designed to last for generations.

They’re built using specialist knowledge and methodologies passed down the generations of Len’s family; skills that allow us to hold back the sea.

Each sea wall is constructed in two parts; the main core of the wall, which must be built in sections - each section completed in full between tides. “This part of the wall is always built using recycled materials. In the case of the Beachlands sea walls, we used rock and broken footpath slabs sourced from Auckland Council held together with concrete to create an extremely strong wall,” Len says.

“The basalt face is is built separately in stages; combined, they create an indestructible wall that will last indefinitely provided it is maintained - with the joints regrounted every 20 or 30 years.” Standing around three metres high, the Beachlands walls - like all seawalls - are comprised of two parts; the main sea-facing wall and second wall slightly back from the first. “The resulting stone platform created between the two walls is planted with native trees - planting that is also protected.”

The Auckland Stonemasons team offers a full service covering design, consent and construction. Find out more about stone sea walls and how they are being used around the country to hold back the sea.