The new clay extraction and backfill area „Eichenallee“ - comprising a total area of approx. 37 ha and an extraction volume of nearly 3.0 million m³ - was authorized by the excavation authorization and the waste management related planning approval decision. For this reaosn, the company Nottenkämper has long-term planning security with regard to the extraction of the clay raw material and also concerning the backfill volume for non hazardous mineral waste (so-called DK I materials). Taking into account the authorized ground elevation of approx. 25 m, the total backfill volume amounts to nearly 10 mio. m³. The excavation and the subsequent recultivation should be realized by 2044. To date, the excavation products and the refill materials were transported by truck over an approach road with certified right of way. However, in addition, the “Egbert Constantin” harbour with loading and unloading facilities, in particular for the requisite backfill materials, will be provided on the nearby Wesel-Datteln canal, which will make the delivery of major volumes of backfill material, e.g. soil, slag and ashes, easier. A site-owned approach route running between the harbour and the deposit site will ensure a transportation distance as short as possible to the backfill point.
The clay pit management is divided into three phases:
- clay extraction and removal of the excavated clay
- backfill and landscaping; and finally
- recultivation and afforestation of the entire surface.
The operation takes place in three different phases:
The surface is divided into eight sections, so that at all times the intervention ensures minimal intrusion. During the clay extraction in the southern sections the northern sections are already recultivated. The sought-after raw material clay is under a layer of sand and loam of nearly 3 m. While the clay deposit in the area of the Eichenallee site extends approx. 50 m into the ground, it is only excavated up to a depth of approx. 15 m on average below the terrain surface. Therefore the lowest excavation point is located nearly 35 meters above the groundwater.
Each excavation section is 500 m long and 100 m wide. The excavation period of each section is nearly two years. The newly created clay surface mine of each section is gradually backfilled in the following step and immediately after recultivated.
A comparison with the legal requirements demonstrates that the local conditions significantly exceed the measures required by law. Instead of the legally required 1,5 m thick natural clay seal here approxiamtely 35 m of clay separate the mineral materials from the ground water lying below. At other landfill locations this natural barrier still needs to be laboriously built up. The choice of the Gartorper Busch site results in the fact that the deposit is considerably more secured than legally required.
On top of the backfill another clay layer is applied providing a 50 times higher density than the legally required insulation. The backfill material is embedded in the clay basin which is aquiclude on all sides. Above the clay barriers, the drainage layers ensure controlled drainage of rain water and leachate.
By the end of 2042 the backfill of the Eichenallee landfill and 80 % of the third phase, the recultivation, will be realized. Therefore the future has already begun.