Groundwater and soil are heavily polluted with VOC
The site was used by a dry cleaning company from about 1930 to 1994. In the process, Volatile Halogenated Hydrocarbons were released into the subsoil and into the nearby Elbe River. The groundwater and the soil in the groundwater fluctuation area are contaminated with considerable amounts of the pollutant Volatile Chlorinated Hydrocarbons (VOCs).
The pollutant discharge of the VOC into the Elbe River 250 m away via the groundwater and via a stream running past the property is to be prevented by soil remediation and groundwater protection.
Large boreholes up to 18 metres deep enable soil replacement
Since January 2021, the soil has been systematically replaced. Large boreholes (DN 1800) are being drilled for this purpose. The drilling rig used for this is one of the largest available of its kind. It weighs about 173 t and reaches up to more than 30 m in height. This method was chosen to extract and dispose of the soil from the groundwater zone up to a maximum of 18 m below the ground surface. At the same time, the outgassing of harmful pollutants (VOC), including tetrachloroethene and trichloroethene, is minimised. The soil material is removed, cleaned and partly reinstalled. This is particularly important because residential development is directly adjacent to the site to be remediated.
A particular challenge: a directly neighbouring residential construction site
The earth movements on the construction site are enormous. As a safety measure, the adjacent residential area was structurally secured. For this purpose, a bored pile wall (DN 1500) was constructed to a depth of 21 metres using a large-hole drilling rig. Thus, from the direction of a watercourse, a drilling platform can be constructed at the level -5 m below the highest surface.
However, a certain noise level cannot be completely avoided. Therefore, an additional sound protection wall was erected during the construction period. Sound level measurements are carried out 24/7 and the results are monitored by the authorities. So far, the local and regional emission protection authorities agree with the precautions taken.
Comprehensive engineering services by spiekermann
Since 2017, the colleagues from the Environmental Services department of the spiekermann branch in Dresden have been accompanying the planning and tendering, as well as the groundwater modelling and subsoil investigations. The colleagues are currently active on the construction site with local construction supervision services, expert monitoring as well as the support and supervision of a post-construction groundwater protection. The construction period is about 7 months in total, with an additional following groundwater protection phase until the end of 2021.
So young and old still have plenty of time to observe the use of machinery and the further development of the construction site.
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