Vulnerability of Groundwater to Pollution 1990
The Environmental Atlas map depicts vulnerability to pollution derived from depth to groundwater from the surface and mantle structure. It should be mentioned here that this map is suitable only for large-areas, but not for the evaluation of smaller areas. Continuing explorations over the last 10 years could not be considered for this map.
The following is a general description of Pleistocene formations. After it there is a description of groundwater vulnerability to pollution on the basis of geology and depths to groundwater from the surface in the geomorphological unit of Berlin.
General Description of Pleistocene Formations
At the end of the Tertiary period (Piacenzian, US = Blancan), a strong cooling of polar areas signaled the transition into the ice ages (Pleistocene period of the Cenozoic era). Heavy precipitation amounts in Scandinavia led to the formation of glacial flows (Scandinavian Ice Sheet). The glaciers moved south, eroding the surface of the earth and transporting huge amounts of rock. Three great ice advances separated by warm (interglacial) ages can be identified in middle and north Europe: the Elsterian, Saalian and Weichselian Ice Ages. Climate warming caused the ice to melt and retreat.
The advance and retreat of the ice sheets created the following landforms (glacial drift):
ground moraine: rock pulverized and abraded by the glacier. The glacial till consists of a heterogeneous mix of clay, silt (rock flour) and sand (boulder marl, boulder clay) and unpulverized blocks of rock (boulders in the marl mass).
end or terminal moraine: formed by rough, often large rock material (plucking of bedrock) transported in front of the glacier. A balance of new ice from the accumulation zone into the ablation (loss) zone over a longer period of time (glacier equilibrium) results in great deposits of blocks of Nordic type rock, often very large, but also of gravel and sand, and some clay.
outwash plain: glacier meltwater washes gravelly, rough and middle-sandy material out of the end moraine into the
glacial valley: outflow area of meltwater.
Between the 3 great glacial advances there were several phases of advance-and-retreat. There were 3 such phases in the Weichselian period: the Brandenburg, Frankfurt, and Pomeranian phases. These phases also followed the dynamics described above. There was an overlapping of several glacial dynamic periods, with each period building its respective formations.
The splitting of the glacier into several glacial streams, each with its own dynamic, had the effect of even more overlapping glacial formations. In areas of smaller glacial landforms, it is often difficult to assign the origin of specific landforms to specific glaciers.
Ground moraine landforms are even more strongly subdivided. One result of meltwater are lakes of various forms, another result is various depositional formations of rock carried by ice (glacial drift). The outflow of meltwater in glacial crevices created deep, narrow channel lakes, such as the Grunewald chain of lakes or the Havel chain of lakes. The eroding action of tongues of ice from inland-ice sheets often created the wide and deep, stretched out tongue-basin lakes. Melting ‘dead-ice masses’, (ice-blocks cut off from the main mass) created non-flowing, water-filled hollows, sinks and sloughs. Ice meltwater washout from the ground moraine carried sand, gravel and blocks to form eskers (from ice crevices and tunnels) and kames (stratified drift sand and gravel deposits in detrial hills), as well as drumlins (elliptical hills with a clay core of boulder marl).
Geology and Vulnerability to Pollution of the Geomorphic Unit Berlin
Barnim flat upland
The Barnim boulder marl flat upland was created during the Brandenburg phase of the Weichselian ice-age. The southern border of this ground moraine runs approximately from Frohnau over Hermsdorf, Pankow, Humboldthain, Lichtenberg (train station), Rüdersdorf and Herzfelde. The Barnim slopes to the south, to the glacial valley (Urstromtal). Boulder marl is on the surface or near-surface. Upland area sand covers it at a few locations, but is not a groundwater aquifer. North of Buch, Karow, Schönerlinde and Hobrechtsfelde, the upland area is covered by washout sand of the Frankfurt phase. Saalian and Weichselian ice-age boulder marl often form compact jams. They are sometimes separated only by a thin sand strata. The main groundwater aquifer is protected in the north by a boulder marl mantle approximately 30 – 40 cm thick, and in the south by a boulder marl mantle approximately 10 – 30 cm thick. The mantle is especially thick in Buch – approximately 50 m. In the area of Hohenschönhausen, Falkenberg, Malchow and Schwanebeck, this main aquifer tapers off northwest towards Panketal. In Weissensee, Pankow and Wedding it splits through interstratified boulder marl into several groundwater aquifers.
A low vulnerability of groundwater to pollution predominates in the Barnim flat upland, at least in view of the mantle strata type (boulder marl >10 m). Pollutants reach the groundwater in the northern upland later than in the southern, because of the greater thickness of the boulder marl.
But the groundwater of this upland area is not completely protected from the entry of contaminants. Channel systems created by meltwater, such as the Wuhle and the Neuenhagen Fliess, break through the protective boulder marl layer and enable the penetration of contaminants. Contaminants can be distributed over long distances because of the groundwater flow and stream conditions (in deeper aquifers also).
The Wuhle is much more endangered, because it is an meltwater channel, and because both natural given conditions, as well as the manner of use at these areas have high degrees of threat. The Wuhle is of sand with a depth to groundwater from the surface of less than 5 m. Sand and boulder marl alternate between Biesdorf-Nord and Eiche. The depth to groundwater from the direct Wuhle to the surrounding boulder marl increases (from < 5 m to > 10 m). The mantle overlaying the groundwater thus shows a high to medium vulnerability to pollution. Nevertheless, domestic waste, debris and building rubble was dumped along the Wuhle for many years (Ahrensfelder and Kienberg dump, debris from Biesdorf). The exact composition of this waste is unknown. Pollutants were and will be dissolved by precipitation and carried into the Wuhle. The insufficiently purified waste water from the Falkenberg sewage water treatment plant, the scrap-yards bordering on the Wuhle, as well as the ‘wild’ waste dumping present an enormous concentration of pollutants. The Wuhle, which begins north of Ahrensfelde, carries this large concentration of pollution into other highly-vulnerable areas through its connection with the Spree in the Pleistocene watercourse.
The natural conditions of the Neuenhagen Mühlenfliess (sand in the valley with a depth to groundwater of 0 – 5 m) also allow the entry of pollutants, whether through percolation or through the surface runoff of contaminated water.
Sewage farm operations in broad areas of the Barnim area (north of Falkenberg and Marzahn to Wartenberg and Malchow) until 1960 (and the continuing use in some cases) caused soils to accumulate high concentrations of heavy metals, nutrients and organic pollutants. The factors responsible for this accumulation in soils, besides the large pollutant concentration in discharged effluents, are the large buffer capacities and the high content of organic substances as well as the Redox/pH conditions (especially from the alkaline character of the treated sewage waters and the large content of dead organic substances). Long-term acid precipitation in discontinued sewage farms caused the redox-potential and pH values in these areas to drop. The exceeding of certain thresholds caused previously bound heavy metals to mobilize. Precipitation or the formation of layer water (existing in sandy boulder marl) could thus discharge pollutants into areas sensitive to pollution. Surface water and groundwater flow towards the southwest in the direction of the glacial watercourse (Urstomtal). The entry and dispersion of contaminant-bearing precipitation and layer water into groundwater aquifers are conditioned by lesser depths to groundwater and a mantle of sand or sand and argillacaeous soils in alternate strata (which predominate south of the Malchow lake, not far from the previously used sewage farms), as well as the location of this area in the flow direction.
Local sand windows (which surely have not all been mapped), or portions of very sandy boulder marl above greater thickness’, or the tearing of boulder marl areas of low thickness by construction activity, all enable entry of pollutants into the flow and stream cycle of groundwater (and not just the upper groundwater aquifer).
An entirely different danger to groundwater, not anthropogenic but rather geogenic, is present everywhere that thin irregularities or absences in rupelton clay exist (formed in the Tertiary Epoch). These irregularities or absences were formed by insufficient deposits or erosion caused by ice. Clay sometimes separates low-mineralized water and highly-mineralized waters. Thin irregularities or absences (such as in Schwanebeck) can allow high-mineralized water to climb from below the rupelton clay up into the near-surface area. This possibility exists mainly in areas where inversions of the natural flow regime occur, often in areas worked by wells which supply drinking water preparation facilities.
The examples presented here should make it clear that even a boulder marl flat upland is not completely protected against entry of contaminants.
Panketal lies between Barnim and West Barnim. The western border is formed by Wilhelmsruh, Rosenthal, Niederschönhausen, Buchholz, Lindenhof, the east surface-rail station Pankow, Heinersdorf, Blankenburg, and Karow. Panketal was created by meltwater during the last ice-age. Fine sand was predominately deposited here. The Panketal has a high vulnerability for groundwater pollution.
West Barnim is the continuation of the Barnim on the northwest side of the Panketal. It is bordered in the west by the Havel lowlands and in the south by the Berlin glacial valley. The map presents only the southern portion.
Subterranean levels are composed of Saalian and Weichselian age boulder marl. The Saalian boulder marl is often split by thin layers of sand. But it only comes to the surface between Blankenfelde and Rosenthal, by Buchholz, around Mühlenbeck, Schönfliess, Stolpe village, and north of Schönerlinde in the form of small and somewhat larger islands. These areas have a low degree of groundwater vulnerability to pollution (depth to groundwater > 10m).
There are depots of surface sand from the Weichselian age between the boulder marl islands. These depots are especially large in the Schildow-Blankenfelde-Arkenberge area. These sands sometimes have argillacaeous layers in more than 20% proportions of total thickness. They are rated as having a medium level of groundwater vulnerability to pollution (depth to groundwater 0 – 10 m).
The outwash plain formations of the Frankfurt phase east of Schönerlinde are overlaid by a ground moraine. Because of the small depths to groundwater from the surface and the coarse grain structures, this area has a high degree of groundwater vulnerability to pollution.
The strongly disturbed subsurface in the southern portion of West Barnim hinders the formation of a groundwater aquifer of larger extent. A higher strata of tertiary sediments in the area of Frohnau-Hermsdorf-Buchholz-Schönerlinde, for example, fall steeply towards the east.
Berlin Pleistocene watercourse
The north border of the Pleistocene watercourse runs from the east along Rüdersdorf, Woltersdorf, Hoppegarten, and Lichtenberg, and bends at the Friedrichshain district towards the northwest, following Pankow, Hermsdorf and Frohnau. The southern border runs approximately from east to west over Schulzendorf, Schönefeld, Altglienicke, Rudow, Buckow, Britz, Schöneberg and Wilmersdorf to south of the point where the Spree flows into the Havel.
The (Warshaw) Berlin Pleistocene watercourse was created as a glacial valley during the Saalian ice age. During the Weichselian ice age it functioned as the outflow valley for meltwater of the Frankfurt phase. It has a slight gradient from southeast to northwest. The deepest location in the glacial valley is Rohrbeck, 30 m above sea level.
Assmann (1957) described the structure of the glacial valley as a five-fold rhythmic deposition of fine sands with local interstratifications of fine clay, medium sands, coarse sands to pebbles, and gravel that could contain drift boulders. The latter are often remainders of washed-out Saalian age ground moraines, which often go over into thin layers of boulder marl, and then lead to a splitting up of the 40 – 55 m thick uncovered groundwater aquifer into several different levels. Sometimes only a few boulder marl lenses are stratified in the main groundwater aquifer, for example in the uppermost layers of valley sand by Charlottenburg (here are remains of the Weichselian age ground moraine).
Remainders of end moraines on the surface form the Müggelberge, the Gosener Berge and the Höhen south of New Zittau. These are composed mainly of sand bearing traces of compression. Channel-like valleys, some of them with lakes, cross the Urstromtal glacial valley in a north-south direction, especially in the Köpenick-Erkner area. Elsterian ice age layers of strongly varying thickness’ appear in the Urstromtal Pleistocene watercourse. They are composed of often changing, sometimes pulverized tertiary sediments. They are not as suitable for supplying water as the sands formed by the Saalian and Weichselian ice ages.
Dunes were formed at the end of the last ice age by blow-outs of fine-grained components from end moraines and especially from valley and Barnim area sands. These were distributed in the Urstromtal glacial valley between Köpenick and Erkner, in the Spandau forest, as well as at Hennigsdorf and at Falkensee. They are up to 15 m thick.
The very slight gradient of the Urstromtal glacial valley (Spree 0.1%) and the high groundwater level facilitated the formation of Holocene peat and half-bog soils. Hollows without outlets, channels and river pools can be filled with these deposits also.
The Urstromtal Pleistocene watercourse, on the whole, has a very high degree of groundwater vulnerability to pollution because of its geological structure. Boulder marl only appears occasionally in thin-layered lenses and thus offers no protection at all against contamination. In spite of this vulnerability, countless industrial operations which impair groundwater and soil quality are located precisely in this sensitive zone. Pollutant entries of dissolved heavy metals accumulated in surface waters from the Barnim upland can occur. The extremely slight gradient and the low flow velocity mean that a concentration of pollutants in the Pleistocene watercourse area as well as in sediments and in surface waters cannot be ruled out.
Teltow flat upland
The Teltow is a flat undulating ground moraine formation south to southwest of the Berlin Urstromtal or the Dahme-Spree Bogen. Its southern borders are the Nuthe and Notte lowlands. The western border is the Berlin and Potsdam Havel area.
The Teltow can be divided into three areas in regard to groundwater vulnerability to pollution:
- northwest portion with Grunewald,
- southeast portion between Britz, Mariendorf, Buckow, Lichtenrade and Osdorf and
- southern portion between Osdorf, Lichtenrade and the Nuthe Notte lowlands.
Northwest portion with Grunewald
The direct northwest edge along the Havel shore consists of kame formations (Havelberge). These stretch south from Ruhleben in a length of about 2.5 km to the north of Schwanenwerder, but become narrower. The eastern border is formed by the lakes of Teufelsee-Pechsee-Barsee-Rinne (lake channel). This ice age formation is primarily of layered sands with individual interstratified layers of pebble and boulders. Sands with less than a 20% proportion of argillacaeous material (clays, silt, brown coal) dominate. This area is classified as having a medium groundwater vulnerability to pollution only because depths to groundwater are more than 10 m. The direct shore area of the Havel has a higher vulnerability of groundwater to pollution because the depths to groundwater are smaller. The well galleries of the Tiefwerder and Beelitzhof waterworks are located in an area without a natural protective layer.
Outflow meltwater from the edge of the ice created the Teufelsee-Pechsee-Barsee lake channel and were later marked by melting ‘dead’ ice blocks. Hollows with no outflow exist here today.
The flat undulating portion of the Teltow runs to the southeast (east Grunewald), and reaches southward to south of the Teltow canal. It is formed of 10 – 15 m thick fluvioglacial sands which have covering sands 1 – 2 m thick. Occasional boulders and local boulder marl lenses are relicts of a ground moraine which overlaid the fluvioglacial sands. The ground moraine was washed out by meltwater from a glacier tongue (Brandenburg glacier) in the area of the Nauener Platte and the Havel.
This area also has a medium degree of groundwater vulnerability to pollution, because the covering mantle is composed of sands with a thickness of more than 10 m.
Southeast portion between Britz, Mariendorf, Lichtenrade and Osdorf
This portion is the core of the ground moraine flat upland and is formed mainly of boulder marl. It is occasionally covered by a thin layer of upland sands, but they are less than 20% of the mantle thickness. The boulder marl is usually more than 10 m thick, often more than 20 m thick, and thus gives the area a low measure of groundwater vulnerability to pollution.
Southern portion between Lichtenrade, Osdorf and the Nuthe-Notte lowlands
The uniform boulder marl mantle in the northern portion is broken up beginning at the Nuthe lowlands by flat, narrow transverse valleys into single islands of boulder marl. This area thus offers many opportunities for the seepage of polluted water. The valleys often contain flat bog peat or sand deposits. This area also has many local sand windows, areas of alternating deposits of sand and argillacaeous strata, as well as thin layers of boulder marl islands (< 5 m thick). These have a high to medium vulnerability to pollution.
The main groundwater aquifer is formed by Saalian ice age sands. A damming mantle of Weichselian boulder marl overlays it, in direct connection with Saalian boulder marl in some localities. This mantle is often split by sands deposited between, so that individual sand strata can be hydraulically connected. Only a few areas have confined groundwater for this reason.
The Bäketal, which sometimes follows the Teltow canal, cut the northern boulder marl areas of the Teltow from west to east or southwest to northeast. It was formed by meltwater of the last ice age. It is composed almost only of sands and organic sediments and has a high vulnerability to pollution. A hydraulic connection with the main groundwater aquifer is questionable.
The Nauen Platte is bordered in the north by the Havelland Luch, in the south by the Brandenburg Potsdam Havel area, and in the east by the Havel. Only its eastern portion is portrayed in the map.
The Nauen Platte originated, like the Teltow and Barnim flat uplands previously mentioned, during the Brandenburg phase of the Weichselian age. It is mainly composed of Saalian and Weichselian ground moraines. These flat-to-undulating, mostly closed-off ground moraine areas are sometimes overlaid by end moraine formations. The central portion of the Platte is composed of clay-to-silt boulder marl. The west and east edges, on the other hand, mainly of sandy boulder marl. The east edge of the Nauen Platte reaches Berlin at Gatow, Kladow and Grossglienicke. The upland sands here are more than 10 m thick, mostly close to and sometimes reaching the surface. The sands have boulder marl only at a few places, such as Seeburg, in the Gatow Heide, and at Karolinenhöhe.
There are favorable groundwater conditions on the Nauen Platte. The aquifers are not very disturbed. They are often split by boulder marl lenses only at the west and south edges. The main groundwater aquifer is a covered aquifer of fluvioglacial Saalian sands with large horizontal distribution. It lies 20 – 40 m under terrain protected by a boulder marl covering, especially in the central part. The partial absence of boulder marl at the eastern edge of the Nauen Platte facilitates the entry of pollutants into groundwater. Water collecting in the higher level sands west of the Havel is also poorly protected against the entry of contaminants. This area can be assigned a medium vulnerability to pollution only because the higher level sands are more than 10 m thick.