Highlight 8-16 of the HRS Guidance Manual
- 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.