Document Type


Publication Date



Bioresource and Agricultural Engineering | Industrial Technology

Course Number and Title

TSM 416: Technology Capstone


Agricultural and Biosystems Engineering


Agricultural Systems Technology (Jamison, Reighard, Russ)


Shweta Chopra and Jacek A. Koziel

Problem Statement

Smithfield Hog Production has several processing facilities across the state of Iowa along with numerous contract finishing farms where producers grow their pigs. The hog manure on these sites is pumped into a slurry store for storage. A slurry store is a 1.2-million-gallon round tank that is 18-feet-tall and 120-foot diameter. Since the slurry store is open to the weather, it accumulates rain, snow, and other types of precipitation.

While evaporation generally equals precipitation, there are some years where precipitation is greater than evaporation. The result is a reduction in manure holding capacity and additional cost to hog production. Also, excess precipitation lowers the per gallon value of the nutrients as a crop fertilizer due to dilution. A cover of some type that would withstand wind and weather would reduce the accumulation of precipitation.

Smithfield has investigated cover designs, but the alternatives cost too much for their producers to implement. Many cover solutions have been implemented in other industries, such as human waste, and universities have researched this topic.

Our team developed a cover for a slurry store structure that will effectively reduce the accumulated rainfall inside the structure and increase the per gallon value of the manure.