Question 7 of 7: Water Resource Management, Greenhouse Effect, Noise Pollution and Environmental Principles

Question 7: Water Resource Management, Greenhouse Effect, Noise Pollution and Environmental Principles (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Protecting a Drinking-Water Lake from Stormwater Runoff

A stormwater treatment train combining a wet detention pond with a constructed treatment wetland, sited to intercept the town's runoff before it reaches the lake, is proposed: the wet pond provides settling and volume attenuation for sediment and coarse pollutants, and the downstream wetland provides biological/physical polishing (nutrient uptake, further settling, some pathogen die-off) before the treated flow discharges to the lake.

Two issues to ensure proper long-term operation and maintenance: (1) periodic sediment and debris removal from the pond forebay and wetland cells — accumulated sediment progressively reduces the design treatment volume and detention time, and can create short-circuiting flow paths that bypass treatment if not removed on a scheduled basis; (2) inlet/outlet structure inspection and vegetation management — clogged inlets, eroded outlet control structures, or overgrown/dying wetland vegetation all degrade the system's hydraulic performance and pollutant-removal effectiveness, and in a Canadian climate winter de-icing salt loading and ice effects on the pond outlet structure are an additional, climate-specific maintenance consideration.

(ii) Two Global Impacts of the Greenhouse Effect and Technical Solutions

1. Sea-level rise. Thermal expansion of ocean water plus melting land ice raises global mean sea level, threatening coastal infrastructure, freshwater aquifers (saltwater intrusion) and coastal communities worldwide. Technical solution: accelerated deployment of low-carbon/renewable electricity generation to displace fossil-fuel combustion, directly reducing the greenhouse-gas emissions driving further warming and sea-level rise.
2. Shifting precipitation patterns and increased frequency of extreme weather (more intense droughts and floods), disrupting water resources and agricultural productivity globally. Technical solution: carbon capture and storage (CCS) retrofit at large stationary emission sources (power plants, heavy industry), reducing the atmospheric CO₂ loading responsible for the climate disruption at its source.

(iii) Two Highway Noise-Reduction Methods and the Preferred Method

Two engineering methods: (1) noise barriers or earthen berms constructed along the highway corridor between the roadway and the residential community, physically blocking the direct line-of-sight noise transmission path; and (2) quiet/porous pavement surfacing combined with traffic management (reduced speed limits, heavy-truck restrictions during nighttime hours), which reduces the noise generated at the tire–pavement source itself.

The noise barrier/berm is generally the preferred method: it typically achieves a larger, more reliable noise reduction (commonly on the order of 5–10 dB where line-of-sight is fully blocked) than source-based pavement treatments (typically 3–5 dB, and one that degrades over the pavement's service life as it wears and requires resurfacing), and its performance does not depend on ongoing enforcement of speed or truck-timing restrictions the way traffic-management measures do.

(iv) Technical and Non-Technical Principles to Control Industrial Air Emissions

A technical principle: install add-on emission-control equipment (e.g., a baghouse/fabric filter or electrostatic precipitator for particulate matter, or a scrubber for acid gases) sized to a specified removal efficiency at the source. A non-technical principle: a market-based mechanism such as cap-and-trade (emissions trading) or mandatory public emissions reporting/disclosure, which creates an economic or reputational incentive to reduce emissions rather than mandating a specific piece of equipment.

The non-technical (market-based) principle is generally more effective in the long term: a fixed technical control only reduces emissions at the one source to a fixed standard and provides no further incentive once that standard is met, whereas a cap-and-trade or disclosure mechanism creates a continuous, sector-wide incentive to keep reducing emissions (through process change, fuel switching or further control investment) because further reduction remains economically or reputationally rewarded indefinitely, rather than only until a fixed compliance line is crossed.