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A Look Back

Between 1994 and 1999, I had the opportunity to write a series of articles for National Petroleum News (NPN). Each article focused on one aspect of the connection between microbial contamination and operational problems in fuel retail systems. In the 13-years that have lapsed since the publication of Uncontrolled Microbes Eat Earnings, our basic understanding of the issue hasn't changed, but the economics have.

Beginning with Uncontrolled Microbes Eat Earnings this month, and continuing with each of the other articles in the following months, Total Fuel Quality is pleased to present reprints of each of my NPN articles with my comments about what has changed since their original publication.

When I wrote Uncontrolled Microbes Eat Earnings, and the other five NPN articles in the series, my intention was to fix an information gap. On one hand, my library of fuel and fuel system microbiology contained several thousand research papers, some dating back more than 100 years since their publication. On the other hand, none of these articles had been published in journals or trade publications that were likely to ever be seen by petroleum marketers, maintenance engineers or quality assurance managers. Uncontrolled Microbes Eat Earnings provided a few very simple model of the economic losses caused by microbes in fuel systems.

Reflecting my field experience at the time, my illustration in Uncontrolled Microbes Eat Earnings focused on bulk storage tanks. That model was based on $0.50/gal gasoline. Multiply the numbers presented in Uncontrolled Microbes Eat Earnings by a factor of 2 to 4 to a sense of the current cost impact.

Now consider a comparable model for retail sites. Assume that at many urban gas stations customers line up waiting to buy fuel during peak periods. For this model we'll use 2- hours per day as the peak period. Some sites experience peak traffic for 4 to 6-hours. Assume the peak hours are only an issue during weekdays. Since it takes time to reposition cars and pay for purchases, fuel can only be dispensed approximately half-of the time (30 min/hour). IF a dispenser is delivering full-flow (10 gal/min) this translates to 300 gal/hour. Using these assumptions, let's compute the effect of a 10% flow-rate reduction on sales.

  1. 10% x 300 gal/h = 30 gal/h lost sales volume
  2. 52 weeks x 5 workdays/week x 2-hours/day = 520 peak-hours/year
  3. 30 gal/hour x 520 hours/year = 15,600 gal
  4. 15,600 gal/year x $3.00/gal = $46,800/year

Note: these numbers assume only a 10% flow-rate reduction. It's not uncommon to find >50% flow-rate loss during flow-rate checks at retail dispensers. Also, the economics summarized above are for a single dispenser. For retail sites with multiple dispensers at which customers line up to wait for fuel during peak hours, the $46,000/year figure needs to be multiplied by the number of dispensers. These are just the opportunity costs (product that could be sold if flow-rate was 10 gal/min).

Since 1994 my consulting work has focused increasingly on problems at fuel retail sites. Most often I help companies perform Biodeterioration Risk Surveys to help them identify current and potential problems caused by microbes (visit for a description of the Biodeterioration Risk Survey). Typically, my clients have had problems at one or two sites. Also typically, they are convinced that they are the only retailers in their region who are experiencing these problems. Consistently, we have found that sites rated as having a high biodeterioration risk score also have the highest corrective maintenance costs. Typically, annual corrective maintenance costs at high risk sites run $2,000 to $5,000 more than at low-risk sites.

Preventing these problems can cost as little as $1,000/year. Few investments provide this type of return. In a real sense, petroleum retailers cannot afford to ignore the cost of uncontrolled contamination.

Next month's reprint - Knowing When You Have Contamination - will review some very easy checks for microbial contamination.

Today, even more than in 1994, you don't have to be a microbiologist to detect and control microbial contamination in your fuel systems. As equipment and operational costs have climbed, so too has the return on investment for implementing a sound microbial contamination control program.

. . .Continue to read rest of article (PDF).

Dr. Frederick Passman, PhD is a Certified Metalworking Fluids Specialist with over 35 years experience in Environmental & Industrial Microbiology. His company, Biodeterioration Control Associates, Inc. (BCA) provides clients with unparalleled expertise in Microbial Contamination Control.

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