Lemnah Drive Gravel Wetland

Since 2023, WHEM has worked with Aldrich + Elliott, PC to support the development of a gravel wetland on Lemnah Drive in St. Albans, Vermont. The project, spearheaded by the City of St. Albans, is designed to treat stormwater runoff from the surrounding industrial park before it enters Stevens Brook, an impaired waterbody that drains to Lake Champlain. The gravel wetland is part of a larger effort to reduce phosphorus loading into Vermont’s surface waters.

As part of pre-construction activities, WHEM completed a Phase I Environmental Site Assessment (ESA) in Fall 2023, which identified historical railroad operations and the presence of fill material as potential concerns. Based on those findings, WHEM conducted a Soil Investigation in February 2024 to assess whether special handling or disposal of excavated soil would be required during construction. WHEM conducted a Supplemental Site Investigation in November 2024, which included additional collection of samples across the proposed gravel wetland practice. Based on earlier findings, samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), lead, and arsenic.

To guide construction and compliance, WHEM prepared a Soil Management Plan (SMP) in accordance with Vermont’s Investigation and Remediation of Contaminated Properties Rule (IRule). The SMP categorized soils into four classifications based on the concentrations of PAHs, lead, and arsenic previously characterized across the site. The plan included a site map which delineated anticipated zones of contaminated soil that had to be appropriately handled and segregated. The SMP also identified an off-site location for soil stockpiling due to limited on-site space.

Throughout excavation, WHEM collected over 20 confirmatory soil samples to characterize and correspondingly manage soils. WHEM then implemented a creative soil management strategy that allowed us to eliminate the need to dispose of soil at the landfill. This strategy included reburial of contaminated soils on-site beneath a notification barrier in conjunction with off-site stockpiling. For soil stockpiled off-site, WHEM is working with the City to permit a City-owned property as a Categorical Disposal Facility (CDF). Once the CDF permit is obtained, soils impacted with PAHs, lead, and arsenic will be able to be spread across the property beneath clean soil. By doing this, the property will be leveled out and allow for the development of recreational fields.

This project underscores WHEM’s role in advancing green infrastructure while managing complex subsurface conditions. Aside from new stormwater treatment, WHEM kept over 4,000 cubic yards of soil from needing to be disposed of at the landfill. Not only did this reduce trucking emissions and save landfill capacity, it reduced project costs by over $500,000. Our work supports the City of St. Albans mission to reduce stormwater pollution and contribute to the restoration of Vermont’s impaired waterways.

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