Polish enthusiasm for new lining techniques

Anna Wrobleweska of Wavin Metalplast-Buk reveals that the increasing use of compact pipe in Poland is the result of a combination of sound market research, promotion and persuading investors and contractors of its benefits.

Compact Pipe, a method developed by Wavin was launched in the West European market in the first half of 1990s, when it came to the attention of Polish investors and contractors. At that time, the U-liner method was the only 'close fit' rehabilitation technique available and the pipeline renovation market in Poland was still at an early phase of development. Initially contractors were not prepared to risk investment in expensive installation equipment.

The first Compact Pipe renovation project in Poland was a 300 mm steel pipe in Plac Macieja, Wroclaw which was completed in August 1997. When the work was successfully completed and the investor gave a positive opinion about the method, many projects followed.

Promotion campaigns and training were intensified and brochures and video films on Compact Pipe were prepared. Technical seminars for potential investors were organised, and Compact Pipe was presented at different conferences. Interested parties were invited to construction sites to evaluate the properties of the method and the true efficiency of contractors.

Compact gains credence
In the three years between 1997 and 2000, over 30 kms of gas, water and sewage pipes and industrial installations were renovated using the Compact Pipe technology - Table 1. In 1999 Compact Pipe technology was chosen to renovate the Szczytniki-Dobrzykowice sewer pressure pipe (DN 400mm and DN 500mm) in Wroclaw, which remains until now the largest renovation project in Poland.

The DN 400mm sanitary sewer in in Poznan is located at the depth of 5-8 metres below the ground level. The groundwater level in this region is relatively high. As the pipe was leaking, considerable quantities of groundwater were flowing into it, which would damage its structure. Since the street was being rebuilt, it was decided to reline the sewer at the same time without reducing its strength. Because of the condition of the sewer and external loads, SDR 17 Compact Pipe was used to provide enough ring stiffness to guarantee stability under large deflections (e.g. due to the destruction of the old pipe) and load (pressure of groundwater, vehicular traffic).

The inner diameter of the manhole of 1m was an additional difficulty, as it was necessary to bend the pipe along a very short radius when it was being pulled in, which required considerable pulling power.

The final result was a close fit liner with a relatively large ring stiffness in the old sewer. Despite the large thickness of the wall, the liner fitted the inside of the pipe so well that it was possible to locate the places in which the old pipe was displaced.

The Dobrzykowice-Szczytniki pressure sewer in Wroclaw is, to the best of the author's knowledge, the largest renovation project carried out in Poland in 1999: 7600 m of DN 400mm pipe and 830 m of DN 500mm pipe. The sewer was built of steel pipes in 1904. Following a nearly one hundred year long use, the abrasion and corrosion wear made continued operation unsafe. More and more frequent failures considerably reduced the sewer's capacity (lower quantity and pressure of wastes transported through it) and the change of the waste flow direction was practically impossible. The sewer passed through a number of difficult and inaccessible places for which a traditional trench would have led to many traffic problems.

Concerns over reservoirs
Environmentalists and ecologists were pleased with the lining of the pressure sewer where it crossed watercourses and in the Szczytnicki Park who feared that due to more and more frequent failures waste would leak and pose a serious hazard to the water reservoirs in that area and to the Odra and Widawa rivers.

The first renovation works were started in June 1999. By the end of August over 3,700 metres of DN 400 pipe and about 600 m of DN 500 pipe were renovated. The works were completed as planned, in December 1999.

In addition, the old DN 400 cast iron water pipe located in Traugutta street in Wroclaw had been damaged by floods and needed renovation. As its capacity was to remain unchanged, methods which minimally reduced the pipeline bore were considered. It was decided to use Compact Pipe and an SDR 17 PE liner. Closed circuit TV inspection revealed a number of surprises. The most interesting of them was a bend fabricated of four 45° segments of pipe to avoid another pipeline. However due to the flexibility of Compact Pipe, this by-pass was overcome. The number of excavations was reduced and the work could be completed earlier than planned.

Industrial applications
Relining of the DN 500 water pipe in PoWoGaz in Poznan is an interesting example of the renovation of industrial installations. The pipe, about 75m long, joins the water meter inspection stations with the factory water tower. The increasing number of leaks of water from the pipe constituted a hazard to the foundations and structure of the buildings.

The location of the starting chamber was the greatest problem. The manhole was located at the far end of a longitudinal extension to the building, and the free space around it very limited. Additionally, the depth of the manhole was very small (about 1m), which meant the liner had to be bent through a small radius. Thus, it was decided to use DN 500 SDR 32 Compact Pipe.

The relatively high flexibility of this liner helped to insert it into the manhole through the hole made in the glass windows of the extension, produced when two adjacent panes were removed. A steel guide helped to insert the pipe smoothly. The liner was pulled through the inside of the sewer, through the 30° bend. Its end was led to the inside of the bottom tank of the water tower. Installation works were made over the weekend, which was important to the investor as production did not have to be interrupted.


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