Landfill Construction – Constructed Wetlands Treatment System, Portland, Maine

SCS Engineers landfill consulting closureSCS Engineers prepared the design and permit application for the closure of Portland’s 40-acre balefill. The balefill consisted of two separate mounds, which had been partially closed with an interim cover system since the late 1980s. The Maine Department of Environmental Protection ultimately required that formal closure of the site be completed, including design preparation and environmental impact assessment.

SCS was tasked with the final cover design, stormwater management, leachate management, site grading plan and related engineering and permit documents. SCS developed several innovative design solutions to address specific site conditions, such as:

Use of Lightweight Fill

SCS utilized a source of lightweight industrial byproducts to provide for filling in areas that had settled to promote positive surface water runoff and reduce long-term future settlement. This creative approach provided a source of revenue to the landfill operator and addressed a challenging site condition.

Constructed Wetlands

SCS designed a remedial strategy for managing/treating uncontrolled groundwater underdrain discharges which had been negatively affected by leachate discharges to the groundwater system. SCS prepared a design concept and detailed engineering plans to treat the contaminated groundwater using a specially designed and constructed wetlands system.

The primary constituents of concern were arsenic, iron and sulfates. Five separate cells were designed to address the treatment and complexing of these various elements and compounds. The substrate design varied depending on the targeted contaminant of concern. The sequence of the treatment cells was critical to the overall projected performance of the system. The system was constructed in the fall of 1998, and initial operation and testing of the system occurred during the summer and fall months of 1999.