About Us

WALO UK Ltd is a specialist in the field of hydraulic asphalt engineering, particularly in providing impermeable barrier systems for the construction and renovation of dam-faces, dam-cores, reservoirs, pumped storage and equalizing reservoirs, artificial lakes, irrigation systems, canals, river banks, landfill sites and coastal protection and flood alleviation schemes.

WALO has now been in the business of providing hydraulic asphaltic barrier systems for the containment of water all over the world for more than 60 years. The company has focused on the constant improvement of processes such as horizontal and vertical laying of bituminous seals. By using the most modern machinery, WALO has also produced results in the construction of landfill seal systems, biotopes, snow reservoirs and parks.

WALO provides a complete service to its customers, both at home and overseas – from initial feasibility studies to designing, manufacturing and installing suitable materials to match their individual requirements for sealing systems in every kind of hydraulic application.

The WALO group, which is wholly owned by the Bertschinger Family, currently employs over 2,300 people. The Group’s objectives are to keep abreast of market forces and to adjust the business to changes in all its fields of operation.

WALO UK Limited is a division of the Walo Bertschinger Group of Switzerland.
The Parent Group was founded in Zurich in 1917 as a civil engineering business and it has subsequently expanded throughout Europe and overseas, developing new enterprises in many diverse fields of operation.

The WALO Group is still a privately owned, family run business today. Initially specialising in developing water storage projects for reservoirs, the company soon diversified and developed its hydraulic asphaltic engineering knowledge into lining dams and canals. In a giant step for hydraulic engineering, WALO created the single layered lining system instead of the double layered system normally specified.

This proved to be of great benefit because it produced a barrier which was quicker to lay and did not have the problem of air pockets forming between the two layers. By the end of the 1970s, WALO had developed a dense asphaltic concrete system for permanently sealing landfill sites, with highly positive implications for the environmental image of the waste industry.


WALO has created a Dense Asphaltic Concrete (DAC) impermeable landfill barrier system, which is impermeable to methane and leachate, found in most solid waste landfill deposits.

Leachate drainage from landfill cells is always a major concern for waste operators, who are under increasing pressure to prioritise environmental considerations. The application of DAC means that landfill sites can now safely house very toxic waste. This is because the resulting contained landfill cannot leach through the impermeable barrier into the groundwater. Many potential sites, such as old quarries, are dismissed out of hand as unsuitable for waste treatment as they have very steep walls. However, landfill designers and engineers looking for practical solutions for landfill lining find that DAC is very stable on slopes, even those as steep as 34º, which means even sites with very steep walls can be used for landfill.

Thus more space can be created for contained landfill while still providing great protection for the environment. Very strong – yet very flexible – DAC is only 34 cm thick and provides decades of impermeable sealing service in the waste treatment industry.

The DAC lining system is perfect for lining reservoirs, canals and irrigation systems as it is non-toxic, impermeable, very strong and still flexible enough to withstand the stress of large volumes of water being pumped in and out every day.

Large ships travelling though canals cause powerful waves but canals lined with DAC can withstand the pressure they create. Long side slopes in these containment systems are not a problem either, as WALO can line slope lengths of 120m or more using specially designed machines which have no need for regular joints – often a major problem for barrier systems.

As well as providing Dense Asphaltic Concrete (DAC) linings to the waste industry, WALO also provides hydraulic asphalt concrete impermeable barrier systems to the water and power industries, lining dams of every size from relatively small projects to major hydro electric plants.

For example, many of Switzerland’s major power stations have large equalising reservoirs which have been lined by WALO using exclusively designed machines built in the company’s own workshops.

WALO’s DAC lining system provides a strong, flexible, non-toxic lining, which is thin enough to flex under extreme pressure without cracking, while being totally safe for human, animal and marine life. These factors make it perfect for water storage.

In addition to lining dam faces, reservoirs, canals and landfill sites, Dense Asphaltic Concrete (DAC) is a very versatile product, useful in all kinds of containment lining systems where an impermeable barrier is needed.

WALO is at the forefront of technological advances in hydraulic technology, which has seen DAC being used for sealing sea defences, coastal groins, irrigation systems, river banks and even for creating snow reservoirs in ski resorts for the production of artificial snow.


WALO has world leading, established, technical engineering knowledge and the necessary modern specialist plant and equipment to provide a DAC impermeable barrier system anywhere and for any situation.

WALO’s Dense Asphaltic Concrete (DAC) lining system, made from clean aggregates, fillers, sand and bitumen is installed using specialised laying and compaction techniques. Due to its high density, DAC is extremely resistant to chemical attack, while being very strong and still flexible.

DAC is specifically designed for use on large slopes and in areas not easily accessible with other materials. WALO has been installing DAC linings since 1939 including one reservoir as large as 1,850,000m2.

Long slopes up to 1:1.5 can be constructed using WALO’s specially engineered equipment and dense asphaltic concrete. Quick to lay, stability is not a problem because WALO’s DAC is always laid to a very high ‘Construction Quality Assurance’.

Any joints required in the DAC system are made strong and totally impermeable by the special treatment and compaction methods employed.

For over sixty years WALO has built on the services of its own laboratory to ensure consistent quality of both building materials and end products.

The lab is engaged in the development and production of formulations as well as in quality control for the production of ready-mixed materials. The company also monitors application or installation work.

WALO’s central Laboratory and mobile labs are accredited test stations for bituminous building materials and surfaces, sealing coats for dam and landfill construction, fresh concrete and concrete, primary and secondary building materials and flooring systems.

Case Studies

Snow Reservoir for producing Artificial Snow

Tyrol, Austria

Enlargement of the Tierfehd Reservoir


Rehabilitation of large pump storage scheme.

Zarnowiec Powerplant,Poland

Cottonmount Landfill

County Antrim, Northern Ireland

Rifa Compensation Reservoir

Rifawerk Hydro Power Plant, Austria

Avce pump storage scheme

Julian Alps, Slovenia

Hornberg Upper Reservoir

Wehr Power Plant, Germany

Chatillon Landfill site

South of Fribourg, Switzerland

Middle Isar Power Station

North East of Munich, Germany

Soelden Snow Reservoir

Austrian Tyrol

Sulby Dam

Isle of Man, United Kingdom

Mastic Renewal of Upper Reservoir at La Muela


Lining Terroba Dam

Rioja Valley, Spain

Reservoir Wag


Obernau Dam


Lostallo Landfill


Markersbach Reservoir


Westmill Landfill Site

Hertfordshire, UK



We have now completed lining the 11th cell at Westmill Landfill site near Ware in Hertfordshire, three weeks earlier than scheduled. This is the largest of the cells we have lined at Westmill since 2003 using Dense Asphaltic Concrete (DAC). The site, operated by Biffa Waste Services Ltd, now has an overall storage capacity of around 2.5 million cubic metres.

We lined the 11th cell with over 13,000 tonnes of asphalt. The basal surface area covers 18,400 sq. m, with slopes of 9,300 sq. m. The longest slope length lined measures 60 m with an incline of 1:2. We also constructed intercell bunds, measuring two metres high, into adjacent existing asphalt lined cells, which cover an area of 3,600 sq. m., again with a slope incline of 1:2. Once the lining works were complete, a leachate collection and removal system was installed.

The work started in the middle of summer and we completed it in just seven weeks, rather than the scheduled ten weeks.


Silvretta Seilbahn AG

Asphalt-Abdichtung Speicherteich Idalpe II

Media Briefing Kit


Contact Us

Please feel free to contact us with any enquiries or to discuss your requirements via fax or email 24 hours a day or give us a call during our normal business hours:


Walo UK Limited, 16 Parker Court, Staffordshire Technology Park, Dyson Way, Stafford ST18 OWP


+44 (0)178 533 0618
Monday – Friday 9.00am- 5.00pm.


+44 (0)178 522 1781


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