Krüger News

Thoughts on thermal soil remediation

News about thermal soil remediation worldwide

Remediation of granite bedrock near Stockholm: what’s challenging and what’s special about the project

Temperatures are rising under the snow on the island of Kvarnholmen. Located only 10 minutes away from downtown Stockholm (the capital of Sweden) with a picturesque view over Royal Park “Djurgården” on the opposite side of the river, the island will definitely be one of the most attractive places to live in. Kvarnholmen is undergoing tremendous development to provide housing for the Stockholm residents. Part of the site is contaminated with PCE, so remediation is required to be able to build houses on the island. Thermal Conduction Heating (TCH) has been chosen as the only valid remediation technology for the site, which consists of granite with a very low porosity. The treatment depth is approximately 30 meters (98.43 ft.). The target zone extends 10 m below the water table which is corresponding to sea level.

Installation and testing of the thermal treatment system has been accomplished successfully, and heating of the granite bedrock started on the 4th of January. Even though the results of TCH are outstanding and TCH is often referred to as an aggressive technology, the heating is very controllable. Average temperature after 20 days of heating is 25 °C. We expect operation to last until end of May.

What’s challenging? Heating fractured rock is very different from heating a porous media like soil. TCH was chosen because of its ability to heat the granite by thermal conduction and thus eventually also the fractures containing the contaminants. Using heating technologies depending on hydraulic conductivity would fail as well as technologies based on electrical conductivity since the rock electrical resistance would be too high. Since water and steam transport basically is restricted to fractures the extraction approach is also very different from a porous media.

What’s special? Kvarnholmen is a special site in many ways. The road from the newly built bridge runs straight through the remediation centre. This means that cars are driving through the thermal wellfield as well as pedestrians and cyclist. Heater wells are located along the road, between the road and bike lane/pavement and along the opposite side of the pavement.

Read more about the project on our client’s website.

TCH – the most versatile subsurface heating technology

In our home country Denmark we are now in the progress of installing a Thermal Conductive Heating (TCH) site in Copenhagen. The geology on the site is dominated by clay, silt and sand. The contaminants of concern are primarily TCE and remedial target is 0.1 mg/kg DM. Most of the contaminated site is located beneath an old two story building housing different companies like a book printing shop and medical lab. These have to stay in operation during remediation with as little disturbance as possible.

We decided to use Thermal Conductive Heating for this site due to its versatile use and flexibility. The target treatment zone with its multiple depths demands a system as flexible as TCH, where we can have individual length on all heater wells if needed. Heating and vaporizing contaminants beneath a building with people working in it, requires a very secure and robust extraction approach. Using TCH, contaminants and steam are driven towards the more permeable zones along the heater wells. Installing co-located extraction screens on all heater wells ensures the most robust extraction. This approach has been used and proven on several sites.

The site is now really busy and a lot of work has been performed so far. We expect to be finished installing all of the wells in the beginning of the New Year. The thermal treatment is designed for 4 months of heating. Stay tuned for further updates. 

Thermal Soil Remediation in Fight against Black Spots

1st December 2016, author: Maiken Faurbye, Krüger A/S

”Management of agro-chemicals: Elimination of Black Spots and Creation of White Spots” was the theme of the conference on Obsolete Pesticides, which took place in the European Parliament in Brussels on September 29th. Krüger A/S received the official invitation to contribute on behalf of MEPs Jordi Sebastià, Margrete Auken and Benedek Jàvor.

Our Department Head Maiken Faurbye held a presentation on Containment problems at a coastal storage of obsolete pesticides in Denmark, where thermal conductive heating (TCH) was described as a possible way of solving the contamination problems in Denmark at Høfte 42. Moreover the IPTD (In-Pile Thermal Desorption) remediation project in Da Nang Airport in Vietnam was presented as an example of an alternative approach to transport, off-site treatment and disposal of highly toxic contaminated soil. Use of the confidential Da Nang case study at the conference was pre-approved by USAID.

The meeting was organised in order to take stock of common challenges and common solutions that the European Union and Eastern neighbours are facing in the implementation of the Stockholm Convention on Persistent Organic Pollutants.

Among the participants were international donor organisations, scientists and experts, NGOs, policy makers at regional and national level in EECCA and EU, Members of the European Parliament, and representatives of all organisations involved in elimination of obsolete chemicals.

The conference was organized together with the International HCH and Pesticides Association (IHPA).

Contamination EXPO Series 2016 in London

1st December 2016, author: Maiken Faurbye, Krüger A/S

It was a pleasure for Krüger to join the Contamination EXPO Series 2016 in London in October, which is UK’s leading event for land contamination professionals to find innovative solutions and technologies.

Krüger's booth stand was well-attended by potential clients and regulators interested in in-situ thermal remediation. Our Product Manager Niels Ploug was among the speakers, presenting the status of in-situ thermal projects in Europe, and was really glad to receive so many positive responses from the participants afterwards.

The presentation went through the key mechanisms of thermal soil remediation and highlighted important parameters to achieve very strict clean-up criteria. Conceptual site model, design considerations, heat transfer modelling, sensitivity analysis are all important aspects of thermal soil remediation. Several case studies were presented to show the variety of Krüger’s sites (from sand to granite) and contaminants (chlorinated solvents to dioxin) treated.

Strength through worldwide partnership

30th of april 2016, author: Niels Ploug, Krüger A/S

Since 2006, Krüger has collaborated with TerraTherm, Inc. using their patented Thermal Conduction Heating (TCH) technology. We offer thermal soil remediation in our home country, Denmark, but also around Europe, Asia, and South America, to name a few.

Performing projects in different countries is challenging since culture, regulation, customs, etc. can vary greatly from country to country. Also, the physical challenges can be very different due to diverse contaminants, infrastructure, and cleanup targets. "Of course every site has its challenges but so far we have reached the clients goals at every single site and not once did we have to stop without succeeding," says Product Manager from Krüger A/S, Niels Ploug.

We are able to perform thermal soil remediation around the world because we are an integrated part of the global environmental company, Veolia. This is a strong benefit for us because no matter where we go in the world, we have a sister business unit there. We do not have to establish new business models with foreign companies, making it easier to manage cultural differences, customs, authorities, regulations, etc.

We have recently finished a complex site in in Switzerland with higher boiling contaminants like 1,2-Dichloro benzene and 4-Chloro-2-Methylaniline. The contaminants were found in both a low permeable zone and high permeable water bearing zone. The solution for this site was a combination of TCH and steam injection. The results of the remediation were impressive and the above mentioned contaminants were treated to an average of 0.28 and 0.37 mg/kg respectively.