In 2007, one of the largest shopping centers in Berlin was opened with the ALEXA leisure and shopping center on Alexanderplatz. The new building with up to four basement levels and several upper floors was built on a floor area of 28.000 m2 under the protection of a watertight excavation pit. The building was partially deep-anchored on a continuous reinforced concrete slab and laterally erected on piles. On an area of approximately 8.000 m2 there was a CHP pollutant plume crossing the construction area. This required measures for the decontamination of the excavation pit and for securing the construction project with regard to the groundwater pollution as well as for securing the flag from carry-over. In addition, it was necessary to decontaminate the filling, which was primarily contaminated with PAHs and heavy metals, up to 5 m thick.
- planning, implementation and supervision of the subsoil investigation
- creating a subsoil expertise including foundation advice
- preparation of the report on the application for water authority approval
- representative for groundwater protection for the entire construction project, including the defense measure to avoid a pollutant carryover
- planning of the excavation pits according to HOAI § 55, Lph. 1-4,6 and 7 as well as § 64, Lph. 1-4 and 6
- local construction supervision for the special civil engineering measures
- vibration measurements and evaluation before and during the construction work
- expert support of the construction project in question of geotechnical engineering, special civil engineering and vibration protection
- historical investigations
- listing of a research concept for waste-technical grid investigations, expert review of the field and laboratory investigations as well as evaluation of the results of the investigation, cost estimation, construction supervision of the decontamination
- limitation of a LCKW pollutant plume crossing the construction site by means of a pumping test, membrane interface sample penetration test and direct-push sampling of the groundwater
- assessment of the burden with regard to occupational safety and pollution control as well as the subsequent use fo the structure, which is to be incorporated into the groundwater up to 12m
- planning and supervision of the implementation of a „sample box“ analog to the construction pit concept to determining the influences of groundwater damage on the construction project with extensive laboratory and measuring program
- public relations: participation in the regulation of urban planning issues with regard to the pollutant plume, coordination with the environmental administration and the city administration
- creating an A+S-plan according to DGUV standard 101-004, formerly BGR 128 for the „sample box“ as well as the entire civil engineering measures
- pre-planning of various restoration and safety measures with the preferred variant „current fuse“ (reactive wall/hydraulic protection) and the decontamination of the excavation put (air-sparging, pump & treat) according to HOAI § 55, Lph. 1-2
- planning of measures to prevent carryover of the pollutant plume by means of 5 wells and treatment of water in a stripping plant including modeling with modflow, adaptation of the measure to the construction process
- planning and documentation of all measures to exempt the property from the suspicions of contamination, obtaining the exemption from the authority
