Our ammonia plant utilization rate at our East Dubuque facility, including planned maintenance shutdowns, has averaged above 90%. Since 1998, our East Dubuque facility has endured industry cycles that precipitated the closure of facilities accounting for over 35% of domestic ammonia capacity. We believe that we have been able to endure these industry cycles in part because of our location-based pricing advantage, and because our facility is configured to efficiently and quickly change our product mix and production volumes to respond to evolving market conditions.
Our Pasadena facility was retrofitted in 2011 to produce the current product slate of ammonium sulfate (AS), ammonium thiosulfate (ATS) and sulfuric acid (SA). Standard on-stream rates are 90% for the AS plant and 95% for the ATS and SA plants, respectively. We are planning to start a major debottlenecking project at the Pasadena facility next year to increase AS production by 20%, from 1,750 tons per day to 2,100 tons per day.
We regularly seek to improve the productivity of our facilities. We maintain and protect the high-value operating equipment at our facilities through multi-faceted maintenance programs and reliability processes executed by a skilled, experienced, and well-trained workforce. Members of our maintenance and operations departments have been employed with our East Dubuque facility for an average of approximately 20 years, with a 22-year average duration for members of the maintenance department and an 17-year average duration for members of our operations department. Our Pasadena facility also has many long-tenured operations employees. Training for our workforce consists of both web-based conceptual subject modules and hands-on benchmark achievement with testing imbedded throughout.
We believe that our proactive maintenance programs and the experience of our workforce at our East Dubuque site minimizes unplanned shutdowns and increases our equipment’s longevity and production rates. We also regularly make investments in our facilities and our equipment to improve our efficiency and reliability. As a result, during each of the last three years, our on-stream rates for our East Dubuque facility were higher than our average on-stream rates over our previous 10-year period. We believe that our operational strategy, which includes regular inspections and maintenance, has been largely responsible for extending the useful lives of our equipment. We will be implementing these processes and procedures at our Pasadena facility to maintain high levels of on-stream rates, productivity and reliability.