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College of Food, Agricultural, and Environmental Sciences

Liquid Manure Storage

Manure storage systems are used on several CFAES dairy and swine facilites. The systems allow for easy cleaning of these animal facilites and the efficient storage of large amounts of raw manure.

Inside the pit or lagoon, the manure undergoes anaerobic digestive fermentation to form fertilizer. The digestive process can generate four potentially dangerous gases:

  • Methane
  • Hydrogen sulfide
  • Carbon dioxide
  • Ammonia

The accumulation of these gases within the confined space of the manure pit can produce an oxygen-deficient, toxic, and/or explosive environment.

Access locations to pits and lagoon areas should be marked with the apporiated "Liquid Manure Storage" signage to warn employees, students, visitors and public of the potentially hazardous area.

Entry into the manure storage area for any reason will require a Confined Space Entry Permit. The Confined Space Entry Permit is the most important tool for assuring safety during entry in confined spaces with potentially hazardous atmospheres. The entry permit process guides our EHS team, supervisors, and workers through a systematic evaluation of the space to be entered. The permit should be used to establish appropriate plan of action for the conditions, before each entry into the confined space. This will also include a plan for emergency rescue / retrieval and emergency responder contacts in the event of an emergency.

If you need a Confined Space Entry Permit, please contact Kent McGuire at or 292-0588 or Cassi Sewell at or (330)263-3663. Additionally, Confined Space Entry Permits can be requested by using the EHS Service Request Form.

Confined Space Written Program
OSU Confined Space Entry Permit & Hazard Analysis
OSU Confined Space Reclassification Form
Research and Extension Agenda for Agricultural Confined Spaces
Staying Safe: Understanding Manure Storage Gases
OSHA: Working Safely Around Manure Storage Structures
NIOSH: Preventing Deaths of Farm Workers in Manure Pits
GPCAH: Gas Hazards in Agriculture


If you have any questions regarding CFAES confined spaces, please contact Kent McGuire at or 292-0588. You may also contact the OSU Environmental Health and Safety Office online at or by phone at (614) 292-1284.


Reviewed / Updated: 12/10/21 K. McGuire