Using spray concrete for water leisure environment

Premier Gunite case study on using spray concrete to create a water leisure environment at Woburn Safari Park, Sea Lion Cove.

Premier Gunite case study: Woburn Safari Park, Sea Lion Cove.

Using spray concrete to create a water leisure environment.

Woburn Safari Park is home to many rich and wonderful species of animals, including Bengal tigers, white rhino, Canadian timber wolves and Asian elephants.

In 2003 they unveiled their new Sea Lion Cove to the public, which is situated in the park's Wild World Leisure Area and is home to male and female Californian Sea Lions.

The Cove was installed by Heritage Pools, a leading UK company who design and construct pools, spas and water leisure environments for the commercial leisure industry and private individuals, while the structural part of the installation was carried out by their sister company Premier Gunite whose spray concrete was used to create the structure, pool shell and the decorative rocky surround.

The Design.

The brief for the installation was to create a water based enclosure where the sea lions could swim, play, rest and most importantly breed, complete with areas for public viewing.

The cove had to serve two purposes; firstly it had to provide a safe and habitable environment for the sea lions and secondly it had to provide entertaining viewing for the park's visitors where people could get close to the sea lions and see them swimming, playing on the pool edges and resting.

Premier Gunite was integral to the design of the cove to allow us to quickly and simply create the structural and design aspects such as the waterfall, sloping beach areas, rocky surround and more.

If we had relied on ordinary shuttered concrete, the build would have taken much longer and involved more complex design challenges commented Brian Andrews, Managing Director of Heritage Pools and Premier Gunite .

Structure.

The structure of the Sea Lion Cove was designed from two different angles.

Firstly it had to be hard-wearing and long-lasting, as Andrews explains The installation had to be extremely strong so that it would last the test of time.

Moving the sea lions is a laborious process and can upset their routine so the cove was built to last.

The brilliant thing about Premier Gunite is that years later the structure will be as strong as the day it was finished Premier Gunite spray concrete was chosen to complete the pool and cove structure for the installation as it is twice the strength of standard shuttered concrete, and is extremely durable, providing a waterproof finish that is resistant to moisture and fire.

Premier Gunite is ideal for creating water filled structures as the finish is salt and fresh waterproof and extremely hard wearing and strong commented Andrews.

Secondly, the structure was aesthetically designed to appeal to the public as an attraction.

The theme of a cove was decided upon with a high OErocky' landscape surround.

This project was a very interesting one to work on as we were able to be really creative and produce a visually interesting structure.

Premier Gunite is ideal for this method of construction as it allows for a fluid free-form design.

explains Andrews.

Premier Gunite uses a OEshortcrete process where the concrete is pre-mixed before being pumped through a hose and spray applied with compressed air onto a light weight shuttered formwork, which is constructed from hardboard and then reinforced with two layers of steel.

The mix used in the spray process consists of 450kg OPC, 450kg aggregate and 1400kg zone two sand mixed with water to a relatively dry consistency.

The consistency of the mixture is crucial, if it is too wet it is of no use as it will simply slide off, it is better to have it slightly too dry and then add water to achieve the ideal mix.

'The mixture we use has a low slump of just 50ml making it the ideal substance to apply to vertical structures', added Andrews.

In comparison, traditional concrete uses a fluid workable mix that is limited in design to the effect of gravity and has to be manually applied by hand so the process takes much longer.

Once the initial structure had been completed including the mass filling of the area with spray concrete to change the shape and aspect, the structural walls were built to form the pool shell, after this, work began on creating the free-form decorative structure of the cove.

A shaped metal frame was affixed to the concrete wall which was then covered with a mesh to ensure the concrete set on the exterior of the frame, before three inches of concrete was sprayed onto it to create the initial OEboulder shape'.

Creating these decorative structures is actually quite an art, once the preliminary shape has been applied, one of our experts then uses a fresco (large trowel) to carve back into the concrete to create the individual rock shapes, the finer details were then picked out using a special paint that is applied directly onto the concrete to add areas of shading and interest commented Andrews.

Entertainment Aspects.

As a public attraction, part of the design included underwater viewing windows to give people the full experience of the sea lions swimming underwater.

35mm bullet proof glass sheets were set into the concrete walls, the strength of Premier Gunite ensures the glass is held securely in place despite the pressure from the 540 cubic metres of water that fills the pool.

The underwater viewing has proved to be a big hit, at the opening we even had a BBC cameraman dive in with an underwater camera to film the sea lion's view of the pool commented Dr Jake Veasey, Animal Collections Manager at Woburn Safari Park.

One of the main concerns for animals kept in captivity is that they will experience boredom and frustration, to keep the Woburn sea lions entertained Heritage installed an interactive waterfall and beach where they could play and rest.

Dr Veasey explained The sloping beach design was to enable the young pups to get in and out as they can't swim when they are born and start to learn when they are about 10 days old.

The Finished Result Three years later the Sea Lion Cove is buzzing.

The breeding programme has been a great success; the cove has attracted hordes of visitors eager to watch these fascinating animals and the structure remains strong and in top condition.

Dr Veasey commented, Since the Sea Lion Cove opened we have had six pups born successfully, so the sea lions definitely like it! It has also become an extremely popular attraction.

Heritage Pools won a SPATA design award for the Sea Lion Cove installation for the ingenuity of design that combined Heritage's expertise in creating innovative water leisure structures with Woburn Safari Park's expertise in animal management.

The finished pool has a footprint of 28m x 20m and a graduated depth of 3.0 metres at the deepest with shallow water and beach areas.

Materials use to create the Woburn Safari Park, Sea Lion Cove:.

Concrete 265 cubic metres.

Steel reinforcement 12 tonnes.

Sand 58 tonnes.

Cement 15 tonnes Stone 300 tonnes.

Salt 6 tonnes.

Water 540 cubic metres.

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