Fig. 2. Color photos of IRIS. The IRIS numbers in parentheses refer to Table 1. (A) A new IRIS never installed in a soil (not in Table 1), (B) IRIS installed in a soil for 14 d showing no removal of FH (46), (C) IRIS installed in the soil for 14 d showing partial removal of FH from part of the tube (48), (D) IRIS showing complete removal of FH from all of the tube (61), (E) IRIS showing some FH removed by organic mass attached to tube surface (7), (F) IRIS showing FH removed at a microsite above water table (9).