Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
Paper format. National Exams, May 2019 — 16-Civ-A3 Elementary Environmental Engineering. Closed book (one 8.5″×11″ double-sided aid-sheet), 3 hours. Seven problems; any five constitute a complete paper (each 20 marks). All seven are solved here as a study resource.
Reference texts. Davis & Cornwell, Introduction to Environmental Engineering (5th ed.); Mihelcic & Zimmerman, Environmental Engineering: Fundamentals, Sustainability, Design (3rd ed.); Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (5th ed.); MWH (Crittenden et al.), Water Treatment: Principles and Design (3rd ed.); CCME Canadian Environmental Quality Guidelines; Health Canada Guidelines for Canadian Drinking Water Quality; Impact Assessment Act (Canada, 2019).
Source note. The seven questions and their sub-part mark splits follow the paper’s own Marking Scheme (page 7): 1 (6/6/8), 2 (7/7/6), 3 (8/5/7), 4 (6/7/7), 5 (10/10), 6 (3/3/4 + 3/3/4), 7 (10/10) — each closing to 20 marks. Where a figure ordinate must be read off a plot it is flagged in a check callout.
7(i) — Protecting a lake source from agricultural nutrient loading. The problem is seasonal N&P runoff driving eutrophication of the drinking-water source, so the three strategies span the pollutant’s path from field to intake:
Source control at the farm (best-management practices). Nutrient-management planning (right rate/time/place of fertilizer and manure), cover cropping, conservation tillage and controlled drainage cut the nutrient load at origin. This is the most cost-effective long-term protection because it prevents the loading rather than treating it downstream. Non-technical lever: agricultural stewardship programs and incentives.
Riparian buffers and constructed wetlands. Vegetated buffer strips and wetlands between the fields and the lake intercept and biologically remove N (denitrification) and P (sorption/uptake) from runoff before it reaches the water — a technical control on the transport pathway that also protects the short term during peak seasonal events.
Watershed/source-water protection planning and monitoring. A statutory source-protection plan (well-head/intake protection zones), land-use controls near the intake, and a water-quality monitoring network (nutrients, chlorophyll-a, cyanotoxins) give early warning and a governance framework that sustains protection over the long term. Non-technical lever: multi-stakeholder watershed governance.
7(ii) — “One Water” strategies for a sustainable municipal system. As municipal engineer I would manage source water, potable supply, wastewater and stormwater as a single interconnected system:
Water reuse and resource recovery. Reclaim treated wastewater for non-potable (or, with advanced treatment, indirect potable) use, and recover nutrients (P) and energy (biogas) from the wastewater stream — closing the loop reduces raw-water withdrawal and returns fewer nutrients to the receiving water.
Integrated demand & stormwater management. Water-conservation/efficiency programs, leak/non-revenue-water reduction, and green-infrastructure/low-impact-development stormwater capture (reducing runoff and CSOs while recharging supply) manage the total water balance rather than each pipe in isolation.
Integrated planning, monitoring and adaptive governance. Manage supply, treatment and discharge under one watershed-scale plan with shared data, climate-resilience allowance (drought/flood), and coordinated capital planning — so decisions on the source, the treatment plants and the collection system reinforce rather than undercut each other.
The unifying idea is that in a “One Water” system the municipality’s own effluent, its stormwater and its source are the same water at different points in a cycle; protecting the lake source (part i) and closing the urban water loop (part ii) are the two halves of a single sustainable strategy.
