The Problem
This project involved a major excavation for a new residential landmark at Fraser Mills, situated adjacent to a sensitive lake ecosystem in Coquitlam. The site faced a critical environmental challenge: groundwater heavily contaminated with iron, peaking at 130 mg/L and averaging between 80–90 mg/L. With a high volume pumping requirement of 1,000 GPM, the primary goal was to prevent excavation flooding while meeting incredibly stringent discharge criteria ($< 1$ mg/L). Any failure in the treatment process posed a severe risk of contaminating the lake, which would have triggered immediate intervention and heavy fines from the Department of Fisheries and Oceans (DFO), resulting in costly project delays for the developer.
The Solutions
Nexgen engineered a sophisticated, multi stage 1,000 GPM ESC treatment system specifically designed for heavy metal remediation. The core of the solution involved the application of a specialized metal chelating agent to chemically bind and drop dissolved iron from the water stream. To provide the necessary volume and residence time for this reaction, we deployed a massive infrastructure consisting of eight 20,000 gallon tanks (one incoming and seven settling weir tanks), supported by two injection units and dual sand filters for final polishing. This setup was strategically designed for operational continuity; by utilizing dual injection lines, our team could vacuum out accumulated sediment from individual tanks without shutting down the entire system, ensuring an uninterrupted work environment.
The Result
The treatment system performed flawlessly, successfully reducing iron concentrations from 130 mg/L to less than 1 mg/L before discharge. Despite the technical complexity and high flow rate, the excavation remained dry and stable throughout the 9 month project duration, with zero dewatering related stoppages. Nexgen’s proactive management ensured 100% environmental compliance, protecting the sensitive lake habitat and maintaining a positive standing with the DFO and city regulators. The project was completed on schedule, demonstrating that even extreme chemical contamination can be managed effectively through advanced engineering and continuous monitoring.
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