1 of 18  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 06: Concrete and Steel Works  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:  Property at 25$^{o}$C  Rubber  PVC  Minimum  tensile  strength  (N/mm$^{2}$)  20  15  Minimum elongation at break  (%)  450  285  Hardness (IRHD/ Shore A)  60 - 75  70 - 75  Softness (BS 2571)  42$^{o}$C - 52$^{o}$C  Specific gravity  1.1 (+5%)  1.3 +(5%)  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  6_Vol3_d4.3_Section 6 Concrete and steel works_en_GIR_rev6.docx 