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More than 1,000m² sealed per day with
Bentofix® and Secudrain®

Location of work/project:



Germany - Hohenwarte

NAUE GmbH & Co. KG

A controllable seal made of geosynthetics at Hohenwarte II pump storage station costs less and was installed far quicker, while simultaneously providing more dependable, long-term performance. Because the pump storage operation places stress on the barrier system, quality assurance in the construction was of high importance.

After more than 50 years of pump storage operation the dam of the Hohenwarte II production facility near Saalfeld/Thuringia began to exhibit high rates of leakage. The site operators opted to update the 15,000m² barrier zone with a more controllable, engineered geosynthetic system.

​After the preparations to better support and protect the forthcoming geosynthetic components, a tie-in drain age channel was added to the mineral seal, an anchor trench was set at the dam crown, and drainage prisms were created. Piping was installed in the prisms and Secudrain® 131 C WD 401 131 C drainage mats were placed from crown to prism. Bentofix® NSP 10300 a geosynthetic clay liner (GCL) was installed upward on the slope and atop the drainage mats, from the drainage channel to the anchor trench. The tie-in trench was filled with high-quality clay and compacted.

The Bentofix® NSP 10300 a, with its 50cm bentonite impregnated edge, provided a self-sealing overlap zone for enhanced barrier performance. Each roll of GCL was produced in such a way that it could be installed without transverse joints.

​Bentofix® panel installation took place with an average installation rate of more than 1,000m² seal accomplished per day. A 30cm-thick sand protection layer was installed atop the GCL, followed by a 20cm thick protection and filter layer made of old filter material.

​Stone revetment was then constructed as the top layer. The construction sequencing and the materials used created a consistent, controlled, high-quality barrier. The geosynthetic system extended 600m in length (approx. 8m below the crown). The slope angle was 1:2.8. The geosynthetics selected for the site enabled a consistent seal quality and efficient installation without interfering with the existing dam geometry.

Geosynthetics saved the site from what would have been a costly, labor-intensive 50cm-thick mineral seal installation. All project parameters and targets were exceeded.

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