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If the nearest intake is 5 miles down the river and 2 miles across the reservior, should you select "River" or "Lake?"

River. Although the intake itself is on a lake (reservior), 5 of the 7 miles from the PPE is in the river.

An unknown quantity of PCBs have been deposited into a wetland that is contiguous to a river and reservoir and has been shown to be present at observed release levels. The toxicity and persistence values (both river and lake) for PCBs are 10,000 and 1, respectively. Calculate the score for waste characteristics for the drinking water threat.

32. Hazardous waste quantity is unknown but shown to be greater than zero by the documented contamination. Therefore, the value from HRS Table 2-6 is 1. This value is over-ridden by the minimum value of 100 because a target in the surface water pathway, the wetland, is subject to actual contamination. 10,000 (toxicity) x 1 (persistence) x 100 (quantity) = 10xE6. The score from Table 2-7 is 32.

Is intake #1 subject to actual or potential contamination? Intake #2? Would the "river" or "lake" value for persistence be used for the drinking water threat?

Intake #1 is subject to actual contamination because it lies within the zone of actual contamination defined by the observed release sample. Intake #2 lies beyond that sample but within the TDL and is considered subject to potential contamination.

What HRS target value would such an intake receive?

165 or 170. 2 points for nearest individual (20 x 0.1 for dilution) and 163 points for population (1,633 x 1/10 for potential and rounded. Another 5 points is possible if any resource values can be documented for the water supply system. For instance, a community pool.


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