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Students Engineer Sustainable Solutions at Walnut Hill Farm

July 5, 2012

Walnut HillBeneath the constant roar of arriving trains at SEPTA 46th Street station three Drexel Engineering and Biomedical Engineering freshman design teams are working to improve Walnut Hill Farm, a sustainable urban farm in Philadelphia’s Walnut Hill neighborhood. What started as a class project has sprouted in to a lesson on going green and giving back.

The teams were asked by Allison Blansfield, the farm’s manager, to solve three issues: create an efficient irrigation system; design a greenhouse to allow year-round cultivation of crops and engineer a plowing system to accommodate the farm’s raised planting beds. The focus of the challenge was to make each solution sustainable in every way:  to people, prosperity, planet, and performance. Over the course of ten weeks each team developed solutions to the farm’s problems. Two teams will implement their designs over the next few months.  The team who designed the irrigation system already has their project in place. 

The irrigation team created a low pressure system of piping and drip tape designed to work in tandem with the farm’s existing solar powered water cisterns. In order for the project to be a success, the team needed a design that was efficient and cost effective.  Their solution irrigates the crops using the minimal amount of required water and costs less than $300.  Irrigation is now available at the twist of a knob, and much less wasteful than the garden hose method currently used. “This is the first time I’ve gotten my hands on something that will be sustainable through the years…being able to make something that will help the community is pretty gratifying,” said Peter Lee, a member of the irrigation team.

Walnut Hill Farm uses 100 percent sustainable farming to grow and sell fresh vegetables to Philadelphia residents. The farm was founded by The Enterprise Center Community Development Corporation in 2010 on vacant land leased from SEPTA for one dollar per year. Currently, the farm grows a variety of produce and sells it on site and at the SEPTA headquarters in center city. The proceeds go to improving the farm and subsidizing low cost produce for the Philadelphia Neighborhood Foods program.

Walnut Hill Farm recently installed six raised planting beds to help retain soil; however, the improvement created a problem. Tilling was now a laborious task. The second team undertook engineering a tool that would make turning the soil in the beds easier. They designed a wooden framed machine that uses L brackets as tilling spikes and strategically placed bicycle wheels to propel it along the 50 foot planting beds. This “intermediate technology” fills a void between hand gardening tools and commercial tractors, serving the needs not just of the plants, but the many volunteers who cultivate them.

With the changing seasons, Walnut Hill Farm was concerned about controlling the temperature in its greenhouse to ensure that plants stayed warm during the winter and cool during the summer. The third team developing a system using Mylar plastic sheeting and a water barrels to create a thermal mass that will help regulate the greenhouse temperature and extend the growing season by months.  The system uses zero fuel and can be easily reconfigured to allow the crops to “breathe” on warmer days.

“These are bright minds and so excited to be designing and implementing something that will have a direct effect…this is an amazing partnership with the University and a community that is just a train stop away,” said Allison Blansfield, Walnut Hill Farm Manager.

The teams were advised by Dr. Alex Moseson of the Mechanical Engineering and Mechanics department and teaching assistants Fela Odeyemi of the Mechanical Engineering and Mechanics department and Ghasideh Pourhashem of the Civil Engineering Department. Each team received sponsorship from Air Products to help pay for the cost of materials.