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Ten Stones is a subdivision located south of Burlington. The original design called for a dosed field with a large area set aside for replacing the eventually failing field. As an alternative, a constructed wetlands was proposed to treat the effluent from each of 13 septic tanks (design flow = 3900 gpd), and then dose the field.

1. Shallow soil cover above bedrock.
2. No community sewer system nearby. Impractical to tie into the city sewer main - extremely high cost.
3. Traditional dosed field requiered set-aside.
4. Concerns about property value - the community needed a system that enhanced the site and was environmentally friendly.

LIMITED FUNDS - The developer wanted to build a low cost system to minimize the financial impact of on-site treatment. The primary economic benefits to the homeowners will be the low O&M costs.

INNOVATIVE TECHNOLOGY - The Ten Stones project is the very first Constructed Wetlands treatment system for a subdivision to be built in Vermont. Data will be collected to allow regulators to monitor the system and understand the effects on soil loading.

DESIGN OBJECTIVES

• Develop a system that blends with aesthetic site conditions while meeting engineering challenges caused by tight soils, hilly terrain, and limited space. Enhance site features and maximize opportunities to lower all costs to the fullest extent possible.
• Meet the Vermont state water quality standards for effluent water being discharged into the ground.
• Minimize the organic and nitrogen loading on the soil; reduce BOD from 160 to 10 mg/L, and nitrogen from 45 to 20 mg/L (average).
• Incorporate ornamental vegetation to enhance the site and create an aesthetically pleasing project.