Summer 2006

Assessing Where to Build


By Colin Johnson, Iowa Pork Industry Center; and Steve Hoff, Agricultural and Biosystems Engineering, Iowa State University

Over time, farms must be modified, expanded and/or replaced. Farms grow due to increased costs of living, increased demand for livestock products or bringing in another generation. Adding livestock is one way to do so. But how does one know where the appropriate location to build a new barn might be? Proper siting is critical to the long term success of an operation from an investment standpoint and for community acceptance. Growth and management of livestock farms must be conducted in an environmentally, economically and socially acceptable manner. Proper siting is critical for minimizing the impact on neighboring residences and locations of public interest.

The state of Iowa has established minimum separation distances for livestock and poultry operations dependent on animal unit capacity (AUC). However, when it comes to odor transport, it must be noted that distance is not equal in all directions. Due to orientation (barn layout and wind direction to neighboring residences) and topography, it is wise to consider multiple factors when siting a barn or expanding a current facility. A tool, which can help, is the Community Assessment Model (CAM).

CAM encompasses an evaluation of the site, including size of facility, species, average inventory and weight, and manure storage type. Community information gathered includes direction and distance to residences, churches, cemeteries and places of frequent public gathering. Other livestock at the proposed site or other locations in the community also are reported. Once this information is gathered, a computer model including local historical weather patterns with wind speed, duration and orientation is used to predict the total hours of potential odor exposure that a point of interest will receive. Hours of odor exposure are reported for three odor concentrations: 2 to 1, 7 to 1, and 15 to 1. For example, an odor concentration of 2 to1 means it would take two volumes of fresh-air mixed with one volume of odorous air to make the odor “barely detectable”. For example, a few states use an odor concentration of 7:1 to assess whether an operation is in compliance relative to odor.

Modeling is conducted for odor release in the eight month time-frame of March to October. This time-frame was selected to encompass the period of time when residents tend to spend a lot of time outdoors. The modeling procedure used is to assess a chosen siting location based on the percent time exposure of a residence to various levels of odor. Currently, site selections are judged based on a limit of a 1 percent time exposure to a 2 to 1 odor and a 0.5 percent time exposure to a 7 to 1 odor. These guidelines and results are given to the producer as a tool to help assess a potential site location.

CAM modeling is based on field-collected odor data and work continues to refine the accuracy and usefulness of CAM.

Modeling potential building sites with CAM provides the farmer comfort in saying ‘this is a good site’ or ‘we need to look at an alternate location.’ The impact of odor reduction methods including biofilters, environmental vegetative buffers, manure storage covers and other air quality mitigation practices can be assessed with CAM to help producers achieve the 1 percent and 0.5 percent guidelines given above. While CAM can help producers in the planning stages of siting new facilities, it is not EPA approved and it will not be recognized by law. However, CAM has been readily received by participating producers and in a few cases has given clear indications where alternate siting choices were needed.

Every community’s understanding of the sites, smells and benefits of livestock farming is different. Assessing the neighboring residences and the role a proposed livestock barn has on the surrounding environment is critical to the long-term success of livestock production in Iowa. If the industry is to remain favorable, livestock production in Iowa must be done in an environmentally, economically and socially acceptable manner. Consideration of neighbors when building new or expanding a current site is important, just as determining the method and timing of manure application. Communicating the story of your family and your livelihood and future plans also goes a long ways. Always consider farm aesthetics and do not forget to involve the community in your farming business. Whether they are crop farming neighbors supplying feed inputs, consumers buying the end products or owners of the acreage next door, all have a stake in the outcome.

If a producer has a concern regarding siting options for a potential livestock barn and would like assistance with evaluating the site, Iowa State University (ISU) Extension partners with the Coalition to Support Iowa's Farmers (CSIF) to offer the Community Assessment Model. Producers may first contact the Coalition at (515) 225-5467. Rex Hoppes, CSIF Organizational Director, has had great experience over the past 20 months evaluating and trouble-shooting building locations in relation to neighbors, topography, aesthetics, and available roads and utilities. The Coalition can offer a vast amount of assistance and where necessary, ISU will conduct a Community Assessment Model with a report available to the producer.


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