Maipo River

The Maipo River in central Chile runs past a metal finishing plant in the town of Puente Alto, where 100 kg of carbon tetrachloride (CCI4) are accidentally spilled into the river. Other compounds were also included in the spill, but the environmental health officials are most concerned about the CCI4. They have decided that all water supply plants on the river should be shut down if the concentration of the pulse is greater than 5 ppb. At what time and how far downstream will this occur ... 

In this reach, on the day of the spill, the Maipo River carried a discharge of 60 m /s, at a mean depth of 2 m, with a mean cross-sectional area of 60 m2 and a stream slope of 0.002. The longitudinal dispersion coefficient is known to be 20 m2/s. 

The time and distance before the peak concentration of CCI4 is below 0.5 ppb is sensitive to uncertainty in the value of K2. We can see that, within a 95% confidence interval, the time when water intakes need to be turned off could vary between 0.8 and 12.4 days, or over 67 to 1,071 km of the Maipo River. The Maipo River, however, is not 1,071 km long, so the entire river below Puente Alto would need to be alerted. 

Table E9.2.1 Expected variation in the times and distance that water supply needs to be shut down on the Maipo River below the Puente Alto spill to maintain CCI4 concentrations below 5 ppb...

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See also in sourсe #XX -- [ ]

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