Jun-2020

In-situ refinery and storage terminal environmental remediation

In the 1960’s there were five refineries built close to Ingolstadt. The location was central to the major refined products markets in Bavaria. The TAL crude oil pipeline brought the required feedstocks through the Alps from Trieste on the Adriatic. Crudes from north Africa, Russia, Black Sea ports and further afield were processed to create petrol, diesel aviation fuels and bitumen.

Stephen B Harrison
Nexant Energy & Chemicals Advisory

Article Summary

After more than 40 years of operation, the activities at one of those refineries were consolidated into two of the others and it closed. That is when Audi had an opportunity to invest in this site with the intent to transform it into a technology park, called IN-Campus. But first, the legacy refinery site needed to be fully remediated with a mix of appropriate environmental management technologies.

In 2017 the consortium consisting of the companies ZÃœBLIN Umwelttechnik GmbH, STRABAG Umwelttechnik GmbH, Geiger Umweltsanierung GmbH Co KG and Wilhelm Geiger GmbH was awarded the contract for the site remediation and preparation for construction. The consortium has been responsible for selection of suitable measures, planning, operation and for obtaining the necessary regulatory approvals.

One for the unique aspects of the site remediation work on this 75 Hectare site is, that most of the activities are taking place in-situ and almost all the excavated material is being returned to the site. Only a small percentage of material is removed from the site for further processing or disposal. Most of the remediation is being completed using equipment that will remain on the site until the clean-up work is complete.

In Bavaria, where the site is located, PFC contamination is taken extremely seriously. During refinery operations, fire fighters practiced using foams, which contained PFCs. These contaminated the soil and groundwater close to the firefighting exercise area. The ‘Guidelines for assessment of PFC contaminants in water and soil’ requires on site treatment of PFC contaminated materials. This guideline is the strictest in Germany and could potentially become a Germany-wide or European guideline and may also be written into national or European law at some point. Therefore, this remediation project in Bavaria may serve as an example that future ex-refinery clean-up operations may be able to learn from in the future.

Bernhard Volz, Senior Engineer at Züblin Umwelttechnik GmbH manages the remediation project for the consortium. He explains, that: “every site has different soil, pollution and target environmental conditions. The technology needs to be selected and the process units must be sized and adapted accordingly”.

Most of the large-scale remediation projects that we have undertaken have returned landfill sites to high environmental standards. Also, we previously cleaned up a former refinery site in Mexico. In Romania we remediated a whole OMV tank farm which has been developed to become the Petrom City in Bucharest”.

The refined products storage terminal in Bucharest was a 20 Ha site on the banks of the Dâmbovița river. It was heavily bombed in 1944 during the second world war by US and German bombers. The bombing raids damaged several tanks and resulted in severe contamination of the soil and groundwater on the site. When the site came to be remediated in 2009, the main contaminants were petroleum hydrocarbons (TPH), poly aromatic hydrocarbons (PAH) and volatile BTEX group chemicals. More than 2.000 Tonnes of oil phase was extracted from the groundwater surface and handed over to Petrom´s refinery for recycling.

In Mexico City, Züblin worked alongside several partners to decontaminate the abandoned Pemex Azcapotzalco refinery. The site was subsequently turned into ‘Parque Bicentenario‘, an urban oasis which now attracts more than a million visitors each year. For more than fifty years the refinery had released lead, benzene and heavy metals into the air, contributing to the city’s reputation as one of the most polluted cities worldwide at that time.

The soil at the old Pemex refinery was saturated with pollutants such as MTBE and chemicals in the BTEX group. Pollution was at an average depth of 3.5 metres but reached a depth of 9m in some locations, resulting in the need to excavate and remediate 1.1 million cubic meters of soil. The groundwater was also heavily contaminated, and a 1,100 m long permanent barrier was sunk into the ground to a depth of 2.5m to ensure that groundwater does not flow to Mexico City’s water distribution system.

Volz continues to say that “our previous downstream energy sector site remediation experience has ensured that we could design and implement suitable processes for the refinery remediation project at Ingolstadt”. He continues to say that “at Ingolstadt the main pollutants are heavy oils, lighter fuels and PFCs. Much of the soil is a mixture of gravel and sand. This means that it is highly permeable, and the remediation project is using a combination of technologies which are suited to the local conditions to return the site to an acceptable state for future use as a technology park”.

Air sparging is used to release volatile pollutants from 10 hectares of land where the refinery and its associated storage tanks once stood. These chemicals are then either incinerated using a flare or catalytically oxidised.

To remediate the groundwater, several boreholes have been drilled at the downstream part of the site to intercept the groundwater before it flows to the Danube River catchment area. From these wells, the groundwater is pumped to the surface where it is purified using a water treatment system which relies on a combination of aeration, precipitation of iron, flocculation, sedimentation, sand filtration and activated carbon adsorption processes. Amongst other things, the process is designed to remove iron-salts and highly mobile PFC chemicals from the groundwater.

1,200 Tonnes per day of contaminated soil from the ground are excavated and thoroughly washed on site in a purpose-built unit constructed and operated by the consortium which is responsible for the site remediation operations. After this washing process, 90% of the excavated gravel and sand can be returned to the site to form a clean and stable foundation for future building construction. A minimal amount of the sludge results from the washing process. This material is compressed to a cake containing most of the hydrocarbon pollutants from the legacy refining operations. It is taken offsite for incineration or landfill.