past projects

Port Vincent in Yorke Peninsula was historically an old port and it served as one of the landing spots for ketches sailing up and down the peninsula. Initially also a homeport of fishermen, the introduction of Government regulations in the late 70s lead to the decline of fishing. The shipping of bagged grain also ended around then. Today, it has reinvented itself as a holiday destination with a magnificent coastline and a sheltered bay. Its establishment as a tourism drawcard was boosted by the building of the $12.2 million Vincent Landing that was completed in 2003. Below is an account of how the locals got involved in the Vincent Landing Marina project 20 years ago. Farmers, some as far as 25km away contributed 45,000 tonnes of paddock rocks for Vincent Landing Marina, a highly venturesome project, now nearing completion at Port Vincent on York Peninsula, South Australia. Locals have stockpiles of limestone rock, created from raking their paddocks over the years. Some weighing up to 3t, from about 20 properties for breakwater construction. “Once we started moving it other farmers kept ringing us,” project manager Peter Lee recalls. Paradise Developments (Port Vincent) p/l is spending $10m on the marina, which is immediately north of Port Vincent and 33 nautical miles across Gulf St Vincent from Outer Harbor. The 50ha site extends one kilometre along the coast and half a kilometre out to sea. It lies beneath 30m high cliffs that overlook, what was formerly a muddy beach.

Opening of Vincent Landing Marina to the Sea – 9 January 2003. December 2002 - 2 x 2000 pipes placed to fill marina while the team went home for Christmas

The completed development will consist of a new excavated harbor protected by two 500m long breakwaters, and a reclaimed 71-allotment residential land division. Both breakwaters and the reclaimed area will be supported by 150,000t of rock, placed on the soft marine clays forming the seabed in order to provide adequate support for the fills above.

Each of the waterfront allotments can have a floating berth capable of mooring a 10-12m yacht. The other allotments are at the foot of the cliffs. Work started in mid-January this year and is due for completion in December. A peak workforce of 40 is using seven hydraulic excavators in the 30-40t range, six 6-wheel-drive articulated trucks, up to 15 semi-trailers and B-doubles plus swamp dozers, loaders and general equipment. At the time of publication the breakwaters are in place, the marina has been pumped dry and about 80,000 of the total 240,000cu m of the excavated material has been placed as fill. Graham Kimber describes the project as ‘adventurous’. Unlike many other inland or on-shore marinas, the breakwaters are in 7m of water and temporarily joined at the marina mouth to form a giant D-shaped bund. This bund must hold back the sea while the enclosed area is pumped dry and excavated to provide a minimum of 3m of water depth at the lowest known tide.

The presence of the sea is emphasised by the sight of excavators and trucks operating up to 8m below where peak tides lap the outer edge of the breakwater/bund. Rock used to support the fill and breakwater cones and to provide armoured protection for the breakwaters and allotment revetments varies from 200mm to 5t (2m3). Four submersible pumps that output 200/sec were used to pump dry, the harbor. They were driven by twin 100 kVA gensets set up on the adjacent bund. The water was pumped into a specially prepared rock basin lined with filter cloth to stop sedimentation entering the sea and the resultant pluming (discolouration). Secci disc readings were taken daily to monitor clarity of the surrounding water. The harbour excavation is to RL-5.5 or about 7m below mean sea level. During the excavation phase pumping was at a reduced level to cope with seepage and natural drainage from the sea floor. The excavated material is levelled and compacted to create the allotments that are filled to a depth of 1 to 4m. On completion of excavation, the harbour entrance will be opened and the marina flooded.

Graham Kimber decided that sourcing of the rock was best served by opening a quarry nearby. A study of Mines Department information maps showed a deposit of Ramsay limestone or dolomite on a farm 20km away. Negotiations with the owners resulted in test drilling to prove the resource. Quarrying began in March this year. The marina will require about 60,000t of rock on the floor of the filled areas and a further 240,000t in and under the breakwaters and facing the revetments. A fleet of 12 vehicles comprising B-doubles, semi-trailers and side-tippers has delivered up to 5,000t of rock a day. Access to the development site has been via a purpose-built ramp down a gully in the cliff face to avoid damaging local roads.

A significant issue in the construction of the breakwaters was the discovery during excavation of particularly plastic and porous marine clays that are difficult to handle when wet, especially in fresh water. Following extensive studies by local and Melbourne-based geotechnical engineers, and testing by FMG at Kent Town (SA) and the University of Adelaide, the revetment rockwork was increased from 700mm to 2m thick. This required

Kangarilla Drilling

the importation of an additional 75,000t of rock and an extension of production at the quarry. As a further precaution, a 2.5m deep cut-off or agricultural drain was installed parallel to the cliff face and just above the filled allotments so that fresh water which continually seeps to the sea from perched inland aquifers is diverted from the marine clays. These clays,

Seagull bogged again having been formed in slat water, are susceptible to weakening and erosion in a freshwater environment.

On completion of filling, the road system, sewers, water and electrical reticulation will be constructed. A 90-berth floating marina will be built within the harbour and consist of four primary fingers each having about 20 serviced berths of varying sizes. Pacific Pontoon & Pier of Brisbane was the construction contractor. The floating units will be made at the company’s Coolangatta facility and assembled and installed at Port Vincent.

The berths will be supported and stabilised by 42, 400mm-diametre tubular steel piles driven into the seabed and encased in a high-density polyethylene jacket that effectively deprives the steel of oxygen and eliminates corrosion. Also to be constructed are a carpark, boat ramp and a beach. The beach will be just south of the southern breakwater and formed by excavating and removing existing foreshore clay and importing clean white sand.

About 4t of fish, mainly whiting and mullet, were removed from the enclosed basin. Locals took as many as they could; the local dump got the rest.

Excavation of the seabed to fill the blocks

As the lunch partner, all you need to do is select 10-15 company executives that you would like to attend. You can expect a total of 15 guests, which includes 2 people from your business, and 3 from CCF SA (including CCF SA CEO).

During lunch, you will be able to present your business to the industry executives. Post event, you will be provided with the contact details of those who attended and also post-print acknowledgement in CCF SA Magazine. Lunches are held at Chianti, Sean’s Kitchen, Georges on Waymouth.

‘Let’s do lunch’ opportunity is provided once per calendar month and are subject to availability. COVID19 restrictions must be complied with at all times. Contact the Members Services team via ccfsa@ccfsa.com.au or 8111 8000 for more information.