Fig. 9. Stability of trichloroethylene (TCE) and tetrachloroethylene (PCE) in the polyethylene irrigation pipe (waterline). The first test of each mini-sprinkler was begun before 1000 h; the second tests were begun after 1127 h. Within each test, bars with the same letter are not significantly different from each other (SAS PROC ANOVA, Duncan's multiple range test, = 0.05).