Description of the Bio-filtration system

Introduction:  The use of biological systems to manage leachate and wastewater is evolving with new technologies and materials constantly emerging.  Greenway at Vassar has spent the last 7 years developing a set of biological materials (soils, indigenous plants, and algae) that are used in innovative earth works called “practices”.   These practices are connected in a linear series, which affords the most effective relationship between the effluent and the filtration material. Greenway at Vassar demonstrates the ability of these systems to control and treat the leachate that is discharged from compost facilities.  All of our practices are dry (separated from surface and ground water) because they are built on impervious surfaces or plastic barriers.

The Greenway Organic Filtration Medium holds enough water and nutrient to keep the landscaping alive through extended dry periods.  Greenway landscape plants can go dormant during extended dry periods and grow quickly in the presence of leachate. The bio-filtration system will take up approximately 27% of the facility and will absorb the first three inches of rain before discharge.  When the facility fills up with water, it releases it very slowly, like a natural wetland.

Greenway’s classifies all stormwater as leachate:  Greenway classifies all the water that runs off of our facility as leachate.  Our  “hot spot” leachate is biologically active. It contains bacteria, nutrient, total suspended solids (TSS), ammonia, grease and oil, (G&O) from heavy equipment operation and composting of manure. 

The leachate that runs off our roads and finished product storage area contains TSS and G&O and a small amount of nutrients.  All of our leachate is treated to insure water quality.

Greenway’s Leachate Management System:  Greenway will manage the leachate using a combination of the leachate management practices and compost facility Best Management Practices (“BMPs”) developed at the Vassar Farm.

Management System:    The goal of Greenway’s leachate management system is to:

• Design a system that is easy to build and performs immediately. 
• Bring our leachate to DEP / DEC standards for reuse on the site.

Greenway has developed an organic filtration medium that is an improvement on the organic sand filter. We have identified and developed indigenous wetland plants such as cattails, swamp willows, sedges, rushes and herbs that can acclimate to the leachate that runs-off our facility at Vassar Farm.  We use our organic filtration materials to fill in and our plants to landscape a series of modified stormwater practices.

Leachate Management Design Features:

Dry swales: An open drainage channel created by earth dikes, landscaped with herbs and grasses, inoculated with green algae, explicitly designed to detain and promote the filtration of leachate as it directs it to our organic filtration medium.

Bioretention Areas: A shallow depression that is created by the check dam and backfilled with Greenway organic filtration medium. This area stores and treats leachate before it flows over the check dams and is returned to the leachate management system.

Greenway Organic Filtration Medium: The Greenway organic filter medium is an improvement on the organic sand filter.  It is a combination of stone, gravel, leaf mold compost, food waste compost, root mulch and detritus wood.

Micropool Extended Detention Ponds: A multiple pond system that treats and stores all water though extended detention ponds and incorporated a micropool at the outlet of each pond to prevent resuspention of silt.

Greenway Bio-Filtration System @ Vassar Farm Recent Operation History

 Background:  The construction of the Vassar Farm compost Facility we done in 1978.  The facility was constructed and operated by the City and Town of Poughkeepsie until they abandoned the site in 2002. Greenway removed the materials stockpiled at the site from 2002-2005 and reopened the facility in 2006.  The biofiltration system was designed and constructed by Greenway.  The facility has been funded 100% by Greenway Marketing Corp.  

 2009 Operations History:

The compost facility received 2.5 million pounds of food waste, 10,000 Cubic Yards of yard waste, and 5,000 Cubic Yards of subsoil in 2009.  The facility received approximately 48 inches of rain in 2009.  Greenway estimates that the compost absorbed approximately 50% of the water. The composting is done on an 80,000 sq ft pad that is on a 2% slope towards the south biofilter. During the course of the year the biofilter received approximately 1,008,000 gallons of leachate.  Greenway has done voluntary testing of our leachate. The wastewater treatment plant sets the standard for discharge water.  Greenway biofiltration system exceeds wastewater treatment standards, landfill leachate standards and stormwater standards.

Table 3 Greenway @ Vassar Bio-filter Water Quality Analyses

Certified lab reports and chain of custody available upon request