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884 Garvin Hill Rd
Greensboro, VT






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The green machine



Jasper Hill Farm has designed and constructed an enclosed, integrated, biological treatment system for managing the manure, whey, and wash-water that result from milking cows and producing cheese. This three-component system employs Aerated Composting for manure solids, Anaerobic Digestion (AD) for phase one of liquids treatment, and an Advanced Botanical System (ABS) for phase two of liquids treatment. Finished compost will be spread on pastures as a soil amendment. Treated water from the ABS will irrigate pastures and extend the grazing season. The integrated design recovers heat energy from the compost to heat the liquid wastes and methane gas from the (AD) tanks used to replace conventional fuel-oil used in our creamery boiler.

background and objectives

Jasper Hill Farm was started by brothers Andy and Mateo Kehler in 2003. The Farm is located in Greensboro, VT, a rural community of 700 residents. Its a typical 'hill' farm, comprised of approximately 100 open acres and 160 acres of mixed woodland. Jasper Hill's award winning cheeses are made from the milk of its herd of 45 registered Ayrshire milking cows. The farm employs an intensive rotational grazing system, feeds dry (un-fermented) feed and produces the cleanest milk in the state of Vermont. Jasper Hll produces approximately 100,000 lbs of cheese per year, and employs 8 full-time workers.

Adept at managing biological systems, Jasper Hill Farm envisioned a 'whole system' approach to nutrient management, waste-water and energy challenges on the farm. An integrated approach will extend Jasper Hill's success upstream to raw product processing and downstream sustainable practices and technologies for Vermont's working landscapes and environment.

Design and construction costs for the Green Machine were made possible in part by grant funding from

Design and Build Team

Project Timeline

  • Project visioning: 2009
  • Schematic Design & Funding: 2010-2011
  • Construction: July 2011 - August 2012
  • Substantial Completion: August 2012
  • Start-up: August - December 2012
  • Field Application, Nutrient Mgmt Plan: Spring 2012


This innovative project integrates multiple waste treatment, nutrient management, and energy recovery strategies into a single "closed loop" system that is scaled to the dairy it serves. Replicability is anticipated in part or in whole and Jasper Hill Farm is committed to facilitating the dissemination of technical design, measured outcomes, and findings from the project.



A traditional tie-barn gutter cleaner removes manure and sawdust bedding from our 50 head cow barn and deposits it into a hopper on top of a separator.

A screw press separator extracts liquid manure and mixes it with cheese house whey and wash-water in a 2,000 gallon pump-station. 

The separated solids are stacked for transfer to our static pile aerated composting shed. The combined liquids are ready for transfer to the Anaerobic Digester.

Composting and Energy Recovery

The manure solids are moved a static-pile composting bay where they will cure for 60 days.

The covered compost shed has aeration channels cast in the floor slab to extract thermal energy from the bottom of the pile while pulling in fresh oxygen to the pile from the top. The piles do not need turning like traditional composting and aeration is managed to maximize the thermal capture of pile breakdown. 

The compost shed is divided into seven aeration zones. A zone will typically climb in temperature for approximately 40 minutes or until it plateaus at 150F. At this time a knife valve opens introducing vacuum to the base of the pile and heat energy is extracted for about 20 minutes or until the pile cools to 100F. 

This aeration cycle is staggered and repeated across the seven aeration zones to maintain a constant 150F heat supply and to consistently re-invigorate piles with oxygen.

A PVC manifold assembly connects the seven aeration zones and serves to duct the hot, moisture-laden air into an iso-bar heat exchanger developed by Agri-Lab Inc

Inside the heat exchanger, the hot wet compost air condenses against an array of refrigerant charged stainless steel tubes transferring energy to an adjacent 250 gallon water tank.

The resulting hot water is circulated through the AD room to heat our three 7,000 gallon Anaerobic Digester tanks.

anaerobic digestion with methane capture


Mixed liquids (whey, wash water, manure) as well as system leachate and condensate are routed into a small scale anaerobic digester. The digester provides primary waste-water treatment, which settles out much of the suspended solids.

This solid mass is broken down by anaerobic bacteria and converted into bio-gas and soluble biochemical oxygen demand. The bio-gas is recovered to provide energy needed for heating water in the creamery, while the clarified effluent is pumped to the advanced botanical system for the second stage of treatment.

Advanced Botanical System

Effluent from the anaerobic digester is channeled through a series of anoxic and aerobic tanks, pumps, and monitoring equipment in the adjacent greenhouse. Remaining biochemical oxygen demand, nutrients, and solids continue to be broken down by a robust ecosystem of plants and microflora in distinct treatment zones.

All the major groups of life are represented, including microscopic algae, fungi, bacteria; tiny animals called protozoa; upward to snails, clams, fish and zooplankton. Higher plants, including shrubs and trees, are grown on industrial strength fiberglass racks suspended within the multi-chamber system. 

The result is an efficient and refined wastewater system capable of achieving high quality water without hazardous chemicals.

Land Application


Once both solids and liquids have reached levels acceptable under our nutrient management plan, both can be land applied. Liquids will be used to strategically drip irrigate pastures and a developing orchard. Finished compost is field-applied to our grazing pastures in accordance with our nutrient management plan to maintain healthy soil conditions, reduce erosion, and improve crop yields over time. Any excess compost is sold for additional income.

the big picture

The implementation of this system has allowed us to better understand the nutrient and energy pathways on our farm, and to harness and re-purpose those resources. As a pasture-based dairy farm, the health of our land and cows are integral to the health of the business as a whole. The new facility affords us more control over the elements that assure quality soil, grass, and cows, so that we can continue to produce the best milk possible for our award-winning cheeses.

for more information

For information about our waste-management system, design specs, or technical questions, write us: