Earthworks

In Bickhardt Bau AG's more than 40-year corporate history, it is one of the largest earthwork sites of all: 5 million cubic metres of soil needed to be moved for the expansion of the airfield of Kassel-Calden into a regional airport. However, in contrast to the kilometre-long new motorway or ICE routes, the entire machine performance was concentrated on an area of 200 hectares. It has been very rare that people have seen such a huge number of these big machines in action in one and the same place so far. At the building site, 55 dumpers, 5 heavy goods vehicles which are usually employed in mining and 15 four-axle vehicles were constantly on the go to transport the soil from the loading points to the installation areas. At minute intervals, they were loaded by the scoops and buckets of the 15 large excavators and giant wheel loaders, with capacities of several cubic metres. With the help of GPS-control systems, 15 caterpillars and five graders ensured a precise installation, with accuracy down to the centimetre. 20 road rollers ensured an adequate soil compaction. Furthermore, several lime spreaders, road milling machines and water tank cars were in continuous operation to improve the soil in partial areas.

With regard to soil movement, 150 qualified employees ensured average daily outputs of 60,000 cubic metres. In the light of a tight timetable for the execution of work, this high labour input became necessary in order to ensure the construction of an even landing strip surface on former agricultural areas with a maximum height difference of almost 30 metres, over a three-kilometre long section.  

The job task of Bickhardt Bau and its ARGE partner also comprised drainage and soil improvement work. In this process, 66,000 metres of vibro-replacement stone columns and 20,000 metres of shallow pits, trenches, several drainages and channel ducts with diameters of up to DN 1400 as well as six rainwater storage reservoirs were constructed. 

Earthworks:

5,300,000 m³ of soil were detached, loaded, conveyed and installed
265,000 tonnes of anti-freeze protection were delivered and installed
800,000 m² of formation level

Soil improvement:

2,900,000 m³ of soil improvement
     33,000 m treated with vibro-replacement stone columns
     700,00 m² of geotextile were delivered and laid

Drainage:

22,000 m of trenches and shallow pits
5 rainwater storage reservoirs
9,000 m of drainage pipes, diameter DN 160 – 250
79 drainage manholes, diameter DN 1000 – DN 2500
300 m reinforced concrete pipe channel

Landscaping:

1,220,000 m³ of topsoil work
1,100,000 m² of lawn seeding

On the right banks of the Rhine, in the area of the municipality of Trebur, between the locations of Hessenaue to the south and Astheim to the north, the existing winter dike was partially removed and newly raised. A proportion of the existing dike material was reused as fill material. Missing material was supplied. The core of the dike body contained a thin diaphragm wall which needed to be secured during the dike removal. The greatest care had to be taken in performing these tasks in this area. The soil compaction was only possible with lightweight construction machines there.

The water-side slope was flattened to an inclination of 1:2.5. During this process, the slope toe was shifted to the water side. In order to achieve a better bond with the water-side sealing layer, the dike body was stepped according to the ZTV-E additional technical terms of contract and guidelines for earthworks in road construction. The water-side slope made of low-permeability soil was installed in layers, and compacted. A site road was constructed on each side of the dike toe. After completion of the building project, this road which was covered with topsoil remains as maintenance and service path in the dike protection strip. On top of the dike, the existing gravel path covered with a mixture of crushed stone fines and chippings was dismantled up to the upper edge of the thin diaphragm wall. The material recovered during the dismantling of this path was used for site roads on the water side.

Earthworks:

60,000 m³ of soil were removed and reinstalled

Dike construction:

45,000 m³ of coarse-grained material
85,000 m³ of fine-grained material
13,000 m³ of gravel material
13,000 m³ of burrowing animal protection

Superstructure:

15,000 m² of bituminous path surfaces

Miscellaneous:

1,200 m³ of reinforced concrete structures
3,200 m² of sheet pile walls