Clean Water - Reservoirs

At the Drinking water treatment plant of Yachiyo-city, water tanks must be maintained. Total water tanks surface area of 3550 m2 must be refurbished and waterproofed.

The lining must have an approval for drinking water application JWWA K-143.

This elevated reservoir was built in 1925 to supply drinking water to the city of Renchen. Because of the outstanding quality of the groundwater that feeds the reservoir, treatment with chemical additives is unnecessary. The used mineral-type coating, which suffered from degradation, disappointed the city’s Department of Public Works, which soon sought a better alternative. At an initial meeting with the owner and contractor, a Sika expert proposed and explained Sikaplan WT 4220, an innovative waterproofing system with new technology, new material, and new components.

The elevated drinking water tanks at Kunigundenruh were built in 1968 (2 x 5’600m³, 1 x 12’000m³). The concrete structure was sealed internally with an epoxy coating and only one year later, due to some leakage, it was additionally lined with a loose laid welded PVC sheet membrane system. After more than 36 years, this membrane had finally become brittle due to loss of plasticizers, some cracks had developed in its surface and it had started to leak. This allowed water ingress to the reinforced concrete structure, especially at the floor to wall joints and also at the intersection with the structural steel support structure. In these areas the concrete had suffered spalling around the corroding steel and it needed to be repaired.

This elevated drinking water tank at Ottenburg is one of the largest (10’000m³) of its type in this region of Germany and it was originally built in 1968. This tank supplies the fresh drinking water for more than 70’000 inhabitants in the region of Freising. “The concrete structure was also internally waterproofed with a cement slurry system, however this had aged and some cracks had also developed through the walls, leading to water ingress; the integrity of the structure was also then endangered as the water leaking into the concrete had led to corrosion of the steel reinforcement” said the project engineer.

The existing water tank was a 185 m3 concrete structure, with a rigid internal waterproof lining system which had begun to leak. The concrete was therefore also in direct contact with the drinking water and this had a negative impact on the water quality. Client and Engineer: Jungfraubahnen AG - Contractor: Neo-Vac AG Oberriet, Switzerland