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If a joint ends at another part of the structure, such as the connection between a wall and a bottom slab, the waterstop shall also be placed at least 300 mm inside the adjacent part of the structure. 

Waterstops shall be placed in accordance with the manufacturer's specifications. Waterstops shall be carefully placed and maintained in position during concreting and compaction operations. Concrete shall be carefully compacted around the waterstops so as to leave no cavities. 

Waterstops shall fulfil the following requirements: 

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The Contractor shall submit details of the waterstops, including a description of the installation of the waterstops, to the Engineer for his approval at least one month before commencement of the formwork at site. 

## 6.1.13 Testing of tanks 

All tanks shall be tested for water tightness in accordance with EN 1992-3. The testing procedure shall be according to the following procedure. 

Excavation for tanks shall not be filled and tank wall faces shall not be coated or plastered outside and inside before the watertightness tests have been passed successfully. 

 The test may not be commenced before the concrete has hardened for 28 days. 

 Filling of tanks with water shall take place with a constant flow rate. The chosen flow rate shall raise the level in the tank not more than 2 m height in 24 hours. 

 A period of 1 week shall be allowed for saturation and stabilization (admission of water into the concrete). 

 Water levels shall be measured by approved means at 24 hours intervals for a test period of 5 days. 

 During the test period the total permissible water level drop, after allowing for evaporation and rainfall, shall not exceed 1/500 of the average water depth of the full tank or 10 mm, whichever is greater. 

The testing procedure shall be used also for small chambers (flow confluence or distribution cham- bers) and for manholes of gravity pipelines. 

Notwithstanding the satisfactory completion of the above test, any leakage or soaking visible on the outside face of the tank walls shall be stopped, after allowing for self-sealing. Any sealing or making 

