Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2013 — 04-Env-B3 / Contaminant Transport. 3 hours duration; closed-book exam (any non-communicating calculator permitted). The paper prints five problems, each worth 25 marks; the source notes state that only the first four problems as they appear in the answer book are marked and that any of a problem's sub-parts may be treated independently. All five are solved below for completeness. The source labels a second, unrelated sub-part of Problem 1 as another “(a)” (a printing quirk noted on the extraction) — it is presented here as Problem 1(c) for clarity, with its own three roman-numeral parts kept intact.
Reference texts. Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (5th ed.); Freeze & Cherry, Groundwater; Cooper & Alley, Air Pollution Control: A Design Approach; Wark, Warner & Davis, Air Pollution: Its Origin and Control.
