DISCHARGE WATER FROM HYDROSTATIC TESTING OF NATURAL-GAS PIPELINES AS SOURCE OF PAH LOADING INTO AQUATIC ENVIRONMENTS

A complex mixture of polycyclic aromatic hydrocarbon (PAH) and alkylated polycyclic hydrocarbons was identified and quantitatively determined in discharge water from hydrostatic testing (DWHT) of natural gas pipelines. The PAH were quantified in water samples drawn from throughout dewatering procedures using selected ion monitoring of particular molecular ions referenced to deuterated PAH internal standards with capillary GC/MS [gas chromatography/mass spectrometry] techniques. Over 100 PAH or alkylated PAH were detected in portions of DWHT using solvent extraction for prefractionation. Concentration of total PAH content showed a clear decreasing trend throughout dewatering from a high value of 32,000 .mu.g/l at start to < 8000 .mu.g/l toward end of discharge. This trend was parallel with bulk hydrocarbon concentrations in the aqueous samples. Consequences for environmental release and disposal practices were discussed based on these results.