18-Env-B4 Site Assessment and Remediation · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2019 — 18-Env-B4: Site Assessment and Remediation (3 hours, open book). Instructions: answer FOUR of the FIVE Section A questions and ONE of the TWO Section B questions; all eight questions (A-1–A-5, B-1, B-2) are answered in full below as a complete study resource. Each question is worth 20 marks.
Reference texts: Nyer, E.K., Practical Techniques for Groundwater and Soil Remediation; Fetter, C.W., Contaminant Hydrogeology (2nd ed.); Leeson, A. & Hinchee, R.E. (1997), Soil Bioventing: Principles and Practice; CSA Z768-01, Phase I Environmental Site Assessment; British Columbia Contaminated Sites Regulation (Environmental Management Act); Ontario Regulation 153/04 (Records of Site Condition); Canadian Council of Ministers of the Environment (CCME), National Classification System for Contaminated Sites and Canada-Wide Standard for Petroleum Hydrocarbons in Soil; Karickhoff, S.W. (1981), organic-carbon partitioning correlations.
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.
Why redevelop brownfields. Toronto's housing shortage collides with a hard land-supply constraint: the city is largely built out, and provincial growth-plan policy (intensification targets under the Growth Plan for the Greater Golden Horseshoe) already directs new housing toward existing built-up areas rather than greenfield expansion at the urban edge. Brownfields — former industrial, rail-yard, and commercial sites — are disproportionately located near the urban core, along transit corridors, and on parcels already serviced by roads, water, sewer, and power. Redeveloping them turns an underused, often blighted liability into housing supply exactly where infrastructure and transit already exist, without consuming farmland or greenspace at the city's edge.
Advantages. Efficient reuse of existing municipal infrastructure (water, sewer, roads, transit) avoids the cost of extending services to greenfield sites; proximity to transit and employment supports the intensification and reduced-commute goals of provincial and municipal growth plans; remediation is a direct co-benefit — contamination that would otherwise sit unaddressed indefinitely gets cleaned up as a condition of redevelopment; a blighted, tax-underperforming parcel returns to the tax base and to productive use; and brownfield programs (municipal tax increment financing, provincial brownfield grants) can offset some of the added cost.
Disadvantages. Remediation and demolition add significant up-front capital cost and schedule risk relative to greenfield construction, and the true extent of contamination is often not fully known until intrusive investigation is well underway, which complicates financing and project timelines; environmental liability can attach to the new owner/developer, which some financiers and buyers remain wary of; regulatory approval (Phase I/II ESA, remediation, and RSC filing) adds months to years before construction can begin; vapour intrusion and residual contamination require ongoing risk management (engineered barriers, sub-slab depressurization) in some cases even after remediation; and community perception of a "toxic" site can complicate approvals or marketing even where the science supports redevelopment.
On balance, given Toronto's specific land-supply constraint, the advantages — particularly avoided infrastructure cost and alignment with intensification policy — generally outweigh the added cost and schedule risk, which is precisely why municipal and provincial brownfield incentive programs exist: to correct for the fact that a greenfield developer does not bear the environmental cost a brownfield developer does.
