Superfund

Highlight 8-16 of the HRS Guidance Manual

Highlight 8-16 : Defining a Single Watershed with Multiple Probable Points of Entry

In this example, two sources are located along a topographic high.
Establish all PPEs for each source.
Determine the TDLs from each PPE:
- The TDL from PPE₁ ends farthest downstream, past the confluence of the East and West Branches (TDL₁).
- The TDL from PPE₂ ends just past the confluence of the East and West Branches (TDL₂).
- TDL from PPE₃ ends on the East Branch (TDL₃).
Since the hazardous substance migration paths for both souces overlap within the TDL, evaluate the inwater segments of North Run, East Branch, and West Branch as a single watershed, using TDL₁ as the TDL for the site.

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