American Society for Testing and Materials is an international standard. ASTM standards are applicable by individual, companies and other institutions around the world. This standard is not mandatory but it can be supported by law of the government. This voluntary standard is applicable for materials, products, system and services. However, ASTM can serve for infiltration and exfiltration acceptance testing of installed precast concrete pipe sewer line. This standard is called ASTM C969M.
Scope of ASTM C969M is a standard procedure for water leak test on installed concrete pipe sewer line. This is not a routine test. Obtained values during testing are applicable only to the sewer tested and time of testing. The values cannot be applicable for other sewer lines. ASTM C969M involves some acceptable rules. Let review these rules. Firstly, before applying leakage test, the sewer line should be cleaned from residue. The manholes, the ends of the branches, laterals, wyes, and stubs to be included in the test shall be plugged. All plugs shall be secured to prevent leakage blowout due to testing pressure. The important point, Infiltration or exfiltration test must be tested between two manholes or more than two manholes. Also, this distance shall not exceed 213m. Stop the water discharging operation and allow the groundwater to turn back to its normal level. The groundwater level must be 0,6 m above the peak of the pipe measured from the highest head of the sewer. The minimum test period must be 15 min and maximum period shall not exceed 24 h. For absorption of water inside the pipe, keep the pipe full by water during min 4 h and max 72 h.
The other important point is allowable leakage limit. This limit shall not exceed 18,5 L/ (mm of internal diameter) (km of sewer) (24h) when the average height on the test section is 1.8m or less. If the groundwater level in the test section is greater than 1,8m, allowable leakage limit must increase by proportion of square root of the average groundwater height to the square root of the base height of 1,8m. In addition, Manholes may be tested separately and independently or with the pipeline with an allowance of 4 L/(m of diameter) (m of head) (h).
After applying all procedure, If the rate of leakage is less than or equal to the allowable limit, the section of sewer tested is acceptable. If the test section fails, it is not prohibited that it be repaired and retested in accordance with practice. Due to the sealing effects of groundwater, internal flow in the sewer line, and test water, the test conditions and results are not repeatable.