It is an artwork that has been shrouded in secrecy for obvious reasons: there are 30 gold bars worth a total of £10,000 buried on the beach in Folkestone and once the tide is out at 4pm on Thursday it's finders keepers.

Organisers of the Folkestone Triennial on Thursday afternoon revealed details of a project it has been desperately trying to keep under wraps. The German artist Michael Sailstorfer has buried gold bullion in the sand of the Outer Harbour beach and once the sea is out, people will be able to come and dig for it.

"I think we might well have a lot of people," said the Triennial curator, Lewis Biggs, with understatement. "It is a participatory artwork. It is about people coming to the beach and digging and possibly finding hidden treasure. Some people will get lucky, some people will not get lucky – and that's life."

The bars are of different sizes and standard gold bullion marked Made in London, although anyone expecting the kind of gold bars you see in heist films may be disappointed. Nevertheless, each bar could be worth several hundred pounds and if you find one – it's yours.

Biggs said the work raised intriguing questions about what people would do with any gold they found. "An interesting part of the artwork is considering whether it is going to be worth more as an artwork. Do you take it to the pawnbrokers or do you take it to Sotheby's? Or do you keep it on the mantlepiece because you think it is going to be worth more later? Will its price increase as an artwork or as a piece of gold?"

The piece, called Folkestone Digs, has been commissioned by the Bristol-based arts producers Situations, an organisation trying to change the perception of what public art can be, its director, Claire Doherty, said.

"So often public art funding is spent on a static sculpture or a bauble on a roundabout and part of what we do is to say, actually sometimes a temporary project can have as much impact in the collective memory as something that has been there a long time." Possibly nothing more so than free gold on the beach.

Doherty said she had no idea who or how many people would respond to the buried gold. Would, she said, the slickly suited art critics down from London for the day be digging alongside members of the public? "What happens will happen. Maybe nobody will go and look."

As well as the fun of finding gold, organisers believe the mass digging of the beach will create its own piece of land art, washed away when the tide comes back in. The next day it can start all over again.

"The piece lasts forever because no one will ever know if all the pieces have ever be found or not," said Biggs. "A lot of people won't admit to having found one even if they have. Would you? We see no end to the artwork. It is meant to be a lot of fun."

The Berlin-based Sailstorfer has chosen not to be in Folkestone for what could become remembered as the great bucket and spade gold rush of 2014. He wants to let "the work unfold," said Doherty. "As simple as that."

Sailstorfer is interested in changing the way people view a place and his previous work includes collecting fallen autumn leaves, painting them green and reattaching them to a tree so it looks like spring. Another involved him feeding the rotting wooden walls of a chalet to a wood burner over the course of a day until nothing remained in the landscape except the wood burner.

Doherty said the Folkestone project fitted in with Sailstorfer's aim of making art "that comes less from the head and more from the stomach". She said the Folkestone work evoked thrilling gold rush stories. "Plus it is childlike, children search for treasure and the seaside is absolutely about that. The digging today will be no different to what has been happening all summer."

There are safety plans in place should it get extremely busy and a number of metal washers have also been buried to fox those who decide to get the metal detector out of the loft.

The Folkestone Triennial itself is in its third edition, a celebration of contemporary art that began in 2008, a way of using culture to help a fading seaside town which said goodbye to its heyday long ago.

Biggs, formerly in charge at the Liverpool Biennial and curating his first Folkestone Triennial, said the town had enthusiastically embraced the concept and this year more than 20 artists had been commissioned including Yoko Ono, Andy Goldsworthy and Pablo Bronstein.

The overall title is Lookout, exploring ideas of looking at the town's past and seeing where its future might emerge. One way of looking at the harbour beach project is that it is the place on which Folkestone was once reliant – it is where tourists sat in their deckchairs, where hovercrafts once went from. Now culture is becoming more important to the town.

Biggs said the Triennial, which officially runs from 30 August to 2 November, was now a focus of interest from around the world. "Artists and visitors are being invited to engage with the history of Folkestone in order to view take a view on what the future might bring."