WATERPROOFING
and to minimise the surface area in order to contain any fire which does occur. For the specifier, building effective bunds will help show that they have discharged their duty of care, while their continuing good condition will be of concern to the Responsible Person formulating the hospital’s fire safety strategy. It may also be the case that a bund can contain the water or other chemicals used by the fire and emergency services to bring a blaze under control, or to cool storage tanks in the event of flames reaching them. There is a further responsibility to ensure that oils and other potential contaminants do not escape beyond the confines of the building and enter the drainage system and thus water courses beyond. Fines and other penalties can be incurred if wildlife or the environment are harmed, so adequate steps must be taken to prevent such occurrences.
Cleaning up spillage
From a practical point of view, if the upstands and floor to a bunded area are fully sealed with an impervious coating, the clean-up of any spillage is made very much simpler: a matter of mopping up and drying off the surface to ensure that it does not pose a slip hazard, rather than an extended deep clean requiring special equipment.
According to the Health and Safety Executive, (HSE) depending on the quantities and variety of liquids being stored, it is advisable to consider the risks posed collectively by the different materials held in a bunded area, with hospitals being the exception. For this reason it is common to create a series of smaller bunds, rather than one larger one; with the option to direct spillages to a separate evaporation area.
Outdoor storage
Where the specifier is dealing with outdoor, and particularly rooftop storage, then provision will have to be made for removing rainwater from within the bund, which will require the installation of either pumped or gravity drainage. Electrical pumps should be located remote from the tank, or be designed not to be able to cause ignition to flammable vapours, while drainage outlets will require a valve
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If the upstands and floor to a bunded area are fully sealed with an impervious coating, the clean-up of any spillage is made very much simpler
Early engagement with a recognised specialist manufacturer of tried and tested waterproofing and other sealant systems can facilitate the design process.
– preferably lockable – to prevent spillages running away uncontrolled. Ideally the base to the exterior bunded area will slope towards the drainage outlet or pump location, and any rainwater be passed through an interceptor, or be held in a buffer tank so that contaminants can be removed prior to discharge.
Consideration also has to be given to the safety of those who routinely have to enter bunds for the purpose of maintenance work. For this reason, a distance of one metre should be kept between the bund wall and storage vessels whose capacity is up to 100 m3 and two metres for larger tanks.
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Early engagement with a specialist Early engagement with a recognised specialist manufacturer of tried and tested waterproofing and other sealant systems can not only facilitate the design process, but also help speed the installation time required, and even shorten the overall programme duration. Such manufacturers will also be able to recommend a shortlist of reputable, approved installers, whose operatives are properly trained in the correct application techniques to ensure performance in practice matches up to the demands of the project. Alternatively, for products such as epoxy-based fluid applied membranes, which can be installed by semi-skilled labour, the manufacturer will be able to offer on-site training or supervision so that the same objectives are achieved.
Indeed, RIW has a national installer network, including companies which concentrate on internal fit-outs, well versed in dealing with the challenges presented by plant rooms. They will be able to offer main contractors or lead consultants proven method statements for addressing different challenges, and be experienced in coordinating their work with that of M&E contractors.
Full design responsibility The company is in fact one of a small number of manufacturers which moves beyond the role of simply being a material supplier, and will actually take full design responsibility for major projects – including working extensively on the construction and waterproofing of multi-storey basements and other sub- structures. RIW has furthermore been involved in the building of numerous healthcare facilities across the country, with its widely specified range of compatible systems employed for both tanking work and the creation of bunded areas to protect plant, personnel, and patients.
When it comes to the design of individual containment areas, the first task for the specifier or specialist installer will be to assess the location where a bund is to be created – looking at its size, configuration, and the condition of the substrates across which the waterproofing system is to be applied. For instance, irregularities in the subfloor, either in the form of unevenness or excessive porosity, will make it far more difficult to achieve a good seal with the underside of a steel angle section. This might require the laying of a levelling compound, as well as a sealant coating able to withstand heavy traffic. Where work is required to level the area, an ideal solution is to utilise one of RIW’s concrete repair mortars, such as RIW Cementfill FC, a fast-setting cement modified repair product. It was developed primarily as a fairing coat for use in structural repair applications – suitable for smoothing and filling minor blowholes or other defects in substrates – which can level both vertical and horizontal surfaces.
No tendency to crack
Unusually, RIW Cementfill FC can be applied from a thickness of 6 mm down to nothing, without any tendency to crack or ‘feather-edge’. The cured material serves
October 2018 Health Estate Journal 93
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