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Field case study  /  Hydrocarbon bioremediation

Firewall soil remediation at a
petrochemical tank farm

Petrochemical refinery complex  ·  Roughly 1,000 square yards

A stockpile averaging over 27,000 mg/kg, and firewall ground around the tanks, both brought below 1,000 mg/kg inside a month.

57,800
mg/kg TPH
at the stockpile peak
Under 1,000
mg/kg TPH
across the whole area
One month
From first application
to confirmation

The site

A tank farm inside a petrochemical refinery complex, where repeated spills had contaminated the soil under and around the firewall.

Over the years, contaminated soil had been dug out of the firewall areas and stockpiled nearby, so the problem existed in two places at once. Samples taken in late May put the stockpiled soil at an average above 27,000 mg/kg with a peak of 57,800. The firewall ground itself ranged from 30 to 4,200 mg/kg.

What we did

The stockpile was spread in a thin layer across an enclosed area of roughly 1,000 square yards beside the tanks. That area and the firewall ground were treated together with a hydrocarbon-degrading microbial blend and nutrients. After the first application the ground was watered for at least four hours a day for a month.

Stockpiled soil
Before treatment
57,800
mg/kg TPH
After treatment
Under 1,000
mg/kg TPH
From 5.8 times over the benchmark to more than 10 times under it Average across the stockpile was above 27,000 mg/kg before treatment
Firewall ground
Before treatment
4,200
mg/kg TPH
After treatment
Under 1,000
mg/kg TPH
Already under the benchmark, and brought lower still The firewall areas ranged from 30 to 4,200 mg/kg before treatment
The benchmark above is the Railroad Commission of Texas cleanup level for crude oil in non-sensitive areas, one per cent by weight, or 10,000 mg/kg. Quoted for scale only. Cleanup criteria vary by state, by programme and by site, and the governing criterion for this site is not stated here.

Follow up samples in late June put the maximum TPH across the entire treatment area below 1,000 mg/kg.

Why it was worth doing this way

The alternative was hauling the stockpile away as contaminated waste and then dealing with the firewall ground separately. Spreading and treating it on site handled both in one pass, on a limited budget, without the soil ever leaving the refinery.

What this does and does not show

It shows that stockpiled soil from repeated petroleum spills can be treated in place, and that spreading it thin and keeping it wet does a great deal of the work.

It does not show that a month is a typical timeframe. This soil was warm, it was spread to a shallow depth, and it was watered daily. Colder ground, deeper material or heavier fractions all take longer.

How the work was done. Delivered through our partnered Houston microbiology and genomics laboratory, which has run this class of work for more than thirty-five years. RAD Microbes LLC was founded in 2024. Contamination levels were measured by laboratory TPH testing in late May before treatment and again in late June.

Start with a discovery call

Every site is different, and a short conversation tells us far more than a sample does. Talk us through what you are dealing with and we will tell you honestly whether biology is the right answer for it. If it is not a fit, we will say so on the call.

Call +1 949 333 9072
or email barry@radmicrobes.com