Civil Engineering - Testing of Gravity Pipelines

    1.  Gravity pipelines laid in open cut shall be tested after they are jointed and before any concreting or backfilling is commenced, other than such as may be necessary for structural stability whilst under test.

     2.   The pipelines shall be tested by means of air and by a visual examination, in lengths determined by the course of construction. Generally pipelines will be tested as complete lines or between manholes.

Visual examinations shall be done by mirror and light, in which case, deviation of plus or minus 20mm, i.e. for 160mm and 200mm pipelines a 75% and 80% clear gauging is required.

3.    A further air test shall be carried out after the backfilling is complete. Failure of this test may require a water test.

4.    Engineer shall arrange for CCTV survey of lengths of sewers.

This survey may be done following completion of certain sewer lines and/or will be done prior to the end of the defects correction period. Should however the inspection of the selected pipelines fail, the Contractor shall first rectify the faults and subsequently arrange for hire of equipment and personnel to repeat the tests and for the survey of any other lengths.

The process shall be repeated at the Contractors expense until satisfied that the whole of the works is constructed in accordance with the drawings and the Specifications.

5.    A pipeline shall have failed the CCTV inspection if any of the following are identified:

·        Any evidence of cradling of the pipes;

·      Any evidence that the pipeline is out of tolerance (e.g. depressions with ponded water, bends in the sidewall);

·        Any dislocated or damaged joints;

·        Any evidence of infiltration;

·        Any projecting connections.

Civil Engineering - Unplasticized PVC Pipes and Fittings used in Sewerage Projects

Unplasticized PVC Pipes and Fittings
1. Unplasticized PVC pressure pipes shall comply with the relevant provisions of BS 3505. Pipes for below ground use for potable water and having an outside diameter less than 75 mm shall be coloured blue.

2. Joints and fittings for pressure pipes in accordance with BS 3505 shall comply with the relevant provisions of BS 4346: Parts 1 and 2 for solvent welded and mechanical joints respectively.

3. Unplastizcized PVC pipes, joints and fittings for gravity sewers and drains shall comply with the relevant provisions of BS 4660 or BS 5481 and shall be of the socket/spigot and rubber ring seal type suitable as sewer pipe laid to a depth of 7 metres in heavily trafficked roads.

4. Solid wall concentric external rib-reinforced unplasticized PVC sewer pipe shall not he used without the approval of the Engineer.

5. UPVC pipes shall be capable of withstanding ultraviolet degradation. A rodent inhibitor shall be incorporated in the material of the pipe.

6. The Contractor shall advise the manufacturer of the climatic and transporting conditions at the site of the Works and shall seek his advice on the storage of uPVC materials on site. Subject to the Engineer’s approval this advice shall be followed at all times.

Civil Engineering - Ductile Iron Pipes and Fittings used in Sewerage Projects

1. Ductile iron pipe and fittings shall be in accordance with BS EN 598 1995 or with International Standard ISO 2531 or such other established and internationally recognized standard providing for requirements equal to or exceeding those of ISO 2531 or BS EN 598 1995.

2. Flanges & bolting shall be confirmed to BS 4504 1969 for 16 bar test pressure.

3. Ductile iron pipe and fitting joints, unless otherwise noted in the Schedule of Quantities, shall be either of the ‘bolted gland’ or the ‘flexible non restraining’ spigot and socket type utilising electrometric gasket rings, at the option of the contractor and to the approval in all respects of the Engineer. A complete set of jointing material shall be supplied for each joint together with an additional 5% of the total material and lubricant as spare.

4. All ductile iron pipes and fittings used for sewerage purposes shall be internally lined with a high alumina cement mortar lining in accordance with section 4.4.3 of EN 598 1994. Externally pipes shall be coated with metallic Zinc covered by a finishing layer of a bituminous product or synthetic resin compatible with Zinc in accordance with section 4.4.2 of EN 598 1994.

5. Pipes for underground installation shall either be externally coated at the manufacturer’s factory and with an approved polythene coating or sleeved at site prior to installation. Sleeving shall be to an approved standard, be adequately restrained and free from tears, pinholes and other damage. An approved proprietary system shall he employed for each pipe joint.

6. Pipes for sections of pipeline constructed above ground shall be supplied complete with materials for an appropriate site applied additional coating system to provide a final finished colour to exposed pipes of either white or aluminium to reduce thermal effects.

7. Polythene coating to ductile iron pipes and fittings shall in its manner of application and characteristics comply with DIN standard 30674.