• Remediation of legacy industrial area
• 16-acre geosynthetic cap design
• Management of existing industrial fill
• Integration with existing stormwater management system
• Significantly reduced O&M costs
GZA designed a geosynthetic cap system as a long-term corrective measure for a 16-acre former industrial operations area in Trenton, Michigan. Industrial activity at the site dates to the early 1940s, and previous investigations found that precipitation infiltrating its permeable fill contributed to a localized groundwater mound. Impacted groundwater was discharging toward the Elizabeth Park Canal and the Trenton Channel of the Detroit River, creating a pathway for arsenic, ammonia, and other contaminants to reach nearby surface waters.
Challenge
Groundwater controls had operated continuously since 2000. Although these systems effectively limited groundwater discharge, they required ongoing operation and maintenance (O&M) and associated long-term costs. GZA also needed to address existing industrial fill, above-ground pipes and tanks, complex grading conditions, and integration with the site’s stormwater infrastructure.
Solution
GZA developed a low-permeability geosynthetic cap to reduce precipitation infiltration, groundwater recharge, and the volume of impacted groundwater requiring active management. The multilayer system includes engineered subgrade materials, a geomembrane, drainage components, protective soil, and vegetative cover. An integrated network of drainage swales directs stormwater to an existing outlet pipe and detention pond. The design also provides for utility relocation, reuse of excavated material within designated fill areas, settlement control, erosion protection, and passive gas venting.
Benefit
GZA’s solution provides a durable corrective measure consistent with Michigan regulatory requirements. By limiting infiltration at its source, the design will help protect nearby surface waters, reduce groundwater management demands, and decrease reliance on, and cost of, active O&M systems.