Laboratory Evaluation of Three Types of PP450 Drainage Synthetic Envelopes for Some Soils of Khouzestan

This investigation was performed to evaluate the suitability of threeSynthetic Envelopes PP450 manufactured by three local workshops in Khouzestan for drainage purposes in three projects, namely, Dehkhoda, Hendijan, and Ramshir projects (respectively, in the north, south, and in the middle of the Khouzestan province). Experiments were performed in the laboratory using an upward flow permeameter. Recommended criteria for the evaluation of the envelopes were steady discharge with time, gradient ratio (GR) for the determination of soil particle movement and envelope clogging potential, and hydraulic conductivity of soil envelope. According to the results for all the three criteria, type 1 envelope (with tiny pores) was considered suitable for Dehkhoda project soils while for Ramshir project soils, based on the same 3 criteria, envelope 3(with macro pores) was the most suitable followed by envelope 1, while envelope 2 (with medium-sized pores) had a lower technical performance for this soil. For Hendijan project soils, envelopes 3 and 2 were partially suitable because hydraulic conductivity of soil envelope was very low. Summing up, envelope 1 and 3 are recommended for Ramshir project and envelope 1 for Dehkhoda project soils .For Hendijan project soils, envelope 3 needs further testing before making recommendation .