site analysis > physical & ecological SOILS The geological basis of Buiksloterham is formed by a 15 to 20 meter alternation of Holocene sand, clay and peat on top of a thick layer of Pleistocene riverbed sand and gravel. On top of the sediments originating from the Holocene is a man-made layer of 2-3 meters of clay and sludge, coming out of the city centre canals. To overcome the high groundwater level, a layer of sand was put on top of this dredge layer. This has raised the ground level to between +0.6m and +1.1m NAP. Due to industrial activities this layer of sand has become polluted with mobile and immobile pollutants. SOIL QUALITY De Ceuvel site is highly contaminated with immobile substances (several heavy metals, polycyclic aromatic hydrocarbons (PAK) and incidentally asbestos). Current plans for De Ceuvel site with phytoremediation through a mix of various grasses that absorb mercury, arsenic, lead, zinc, manganese and aluminum. WATER SOIL QUALITY The sludge of the Schoonschip site is highly contaminated with heavy metals, in particular mercury, copper, zinc, lead and arsenic and moderately contaminated with other substances under examination. There is no obligation to remediate the sludge. GROUNDWATER The polluted dredge layer has formed an impervious layer, causing high groundwater levels, which is a major problem to the area. SURFACE WATER The surface water of the IJ, the canals and the harbors meet the general standards for pH (acidity), transparency, oxygen, temperatures and heavy metals. The yearly average concentrations of phosphate, nitrogen and copper are, however, above the MTR level (maximum allowed risk), which is mainly caused by the several water outlets. Therefore, the current mixed sewage system will be replaced by an improved separated system, improving the surface water quality substantially. BIOLOGICAL WILDLIFE The area is characterized in the Ecological Atlas of Amsterdam (2012) as the biotope ‘bebouwing’ (buildings). The animals of these biotopes in Amsterdam are characterized by either actively or passively using the food made available by humans. Thus, mainly ‘urban’ birds can be found (Swiſt, Urban Dove, (House) Sparrow, Brown Rat, Little Bat, Tongue Fern, Wall Fern). For the selected area, the protected species are the ‘Gierzwaluw’(Swiſt) and the ‘huismus ‘(Sparrow). These protections make that some considerations need to be taken into account when building, especially in the months of March – June; sufficient nesting possibilities and providing some urban wilderness for food is required. The remainder of the possible present species for this area is Starling, Jackdaw, Treecreeper, Collared Dove. VEGETATION Regarding vegetation for the Schoonschip site, there are around 23 trees situated on the edge in combination with some bushes and shreds on the bank of the canal (see Appendix E, Figure 2). None of these trees or vegetation are of any threatened species or have any protected status in the form of monumental green. De Ceuvel site has more abundant vegetation and habituates 42 trees, of which 4 trees are protected with a monumental status. Next to the trees, there is an abundance of bushes and weeds and related species situated on the site, but with no special protected status. Possible species are Limestone Oak Fern, Henbane, Belladonna, Wild Lettuce, Halsbloem (Trachelium caeruleum), Trailing Bellflower, Latin American fleabane, Flattened Meadowgrass, Valerian and Common Fig. AQUATIC ECOLOGY No specific measurements or assessment of the aquatic ecosystem of the Johan van Hasseltkanaal have ever been performed. The water in the Johan van Hasseltkanaal comes from the Noordzeekanaal and its aquatic ecology is thus mainly determined by the state of the systems in this canal. In the report of Rijkswaterstaat (2009) on the Noordzeekanaal of 2009, the ecological quality of the water is mainly determined by the quality of the following elements: phytoplankton, macrophytes, macrofauna and fish. A table of the last studied situation is given in Appendix E, Table 1. In this report, several bottlenecks for the Noordzeekanaal were identified, but none of specific consequences or effects for the Johan van Hasseltkanaal. 104 / 146 Pagina 103
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