DE19930699A1 - Pool for the retention of surface water - Google Patents

Abstract

In the case of a trough-shaped basin sealed with a plastic sealing membrane for the retention of surface water in an area with a high groundwater level, there is a trough sealed against the groundwater with a bed of ballast material underneath the basin. The plastic sealing membrane for sealing the tub and the plastic sealing membrane for the basin are tightly connected to each other in the area of a wall. The ballasting of the pelvic seal to prevent the effects of the buoyancy caused by the groundwater below the pelvis is thus enclosed in a tub which is also sealed off from the groundwater, as in a pillow, as a result of which it remains dry and cannot lose its function as ballast.

Description

The application relates to a sealed with a plastic sealing membrane Basin in an area with a high groundwater level for cleaning and Retention of surface water, that of road, rail or other paved surfaces.

The water running off roads or other paved traffic areas is legally considered wastewater to be treated. Retention and / or separating basins, which are often used as plastic sealing sheets sealed earth basins. They are used to save the incoming water quantities and for throttled discharge into the receiving water as well as for cleaning the water from suspended matter and separable Liquids. In the "Guidelines for the construction of roads RAS part: Drainage (RAS-Ew) ", published by the research society for Road and traffic systems are standard drawings for the training of such Basin shown.

For pools in areas with high groundwater levels, such as in floodplains Lakeside or near moor areas need special manufacturing Measures are taken to lay the pool seal in the dry and to be able to weld. To do this, you have to use a well with pumps or even by enclosing the construction site with sheet piling the water level of the Groundwater can be lowered to below the bottom of the pool.

If the basin is emptied for maintenance work, the seal against Buoyancy can be secured. This is done by installing thicker ones Soil layers, the cubature of which still needs to be increased because of the material is buoyant, and is therefore considerably lighter. This causes the expensive Excavation of a large amount of wet soil, which usually has to be removed. Gravel must be supplied as a replacement floor. These soil layers will be in the event of accidents involving chemicals or contaminated extinguishing water  Vehicle fire contaminated. You then have to pay enormous costs as Hazardous waste to be disposed of.

As an alternative, the groundwater level must always be up to the level of the Waterproofing sole can be lowered.

The aim of the invention is under the actual sealing layer for the Retention basin a tub sealed against the groundwater with a Ballast material filling to protect against buoyancy without interfering with the Establish groundwater balance.

According to the invention to reduce the excavation quantities as ballast material Electric furnace slag from the steel industry is used, which is 1.5 times has higher weights than normal earth material.

The invention is explained below with reference to the drawing; it shows

Fig. 1 shows a section through a retention basin according to the invention and

Fig. 2 shows a detail of Fig. 1 on a larger scale.

To build the retention basin, a surface with a geometrically simple shape that goes beyond the later basin size is excavated about one to two meters above the planned basin floor ( 4 ) and the excavation floor ( 3 ) and the embankment surfaces are then smoothed out. The excavation area ( 2 ) fills up to the natural groundwater level ( 5 ) with water. Drainage pipes are laid on the embankments and suction hoses for pumps are inserted. A sealing tarpaulin ( 6 ) made of flexible plastic sealing sheets welded at the factory or next to the basin is pulled over the excavation area ( 2 ) and temporarily secured. A nonwoven mat ( 13 ), the individual webs of which are sewn, is then pulled over the already installed sealing tarpaulin ( 6 ). In the area of the pelvic floor ( 4 ), stabilizing elements ( 7 ) are designed to prevent the first ballast layer ( 12 ) from slipping.

Then, with an excavator that has a boom with a suitable reach, electric furnace slag is installed as a ballast layer ( 12 ) on the excavation base ( 3 ) and then on the embankments. The groundwater displaced by the ballasting is sucked off by the pumps under the sealing tarpaulin ( 6 ) and directed into a receiving water. If the sealing tarpaulin ( 6 ) lies under the weight of the ballast layer ( 12 ) over the entire surface of the substrate ( 1 ), the pumps can be switched off and removed.

A closed plastic pipe ( 10 ) is laid between the low point of the waterproofing tarpaulin ( 6 ) and the edge of the pool on the inspection shaft and temporarily attached outside the waterproofing tarpaulin. A second short piece of pipe ( 11 ) is laid next to it. In future it will be used to ventilate the ballast layer ( 12 ).

By using electric furnace slag as a ballast layer ( 12 ), a third of the normally necessary excavation depth is saved. Furthermore, there is no need to reduce buoyancy by installing it inside the trough-like waterproofing tarpaulin for the soil to be installed below the water table ( 5 ). The excavation depth is halved again for this area.

The inlet pipe (s) ( 21 ) and the pool outlet ( 22 ) are guided above the groundwater table ( 5 ) through the sealing tarpaulin ( 6 ). In the embankment areas, concrete collars are made around the pipes and the surfaces smoothed. The sealing tarpaulin ( 6 ) is attached to these surfaces with clamping rails and sealing tape.

The sealing tarpaulin ( 6 ) is laid about 2.00 m outside the pool edge in an anchor trench ( 9 ). This is then filled in and the filling material is compressed. A peripheral wall ( 8 ) is arranged between the anchor trench ( 9 ) and the edge of the excavation basin, which is 15 cm higher than the rear edge of the sealing tarpaulin ( 6 ) in the anchor trench ( 9 ). This prevents water that has accumulated from seeping out from under the pool seal ( 15 ).

The desired shape of the separation and retention basin is then made with additional bulk material made of electric furnace slag and finally covered with sand material of the same type. A nonwoven mat with a surface weight of 500 g / m ^{2 is} laid on the sand layer as the lower protective layer ( 14 ).

The basin seal ( 15 ) is then installed with plastic sealing sheets made from modified polyethylene or thermoplastic olefins, which have sufficient resistance to the chemicals occurring in road wastewater after accidents. The pool seal ( 15 ) is tightly connected to the pipes of the inlet ( 21 ) and outlet ( 22 ). A control and maintenance shaft ( 23 ) for the drain is then created outside the basin. The drainage pipe ( 10 ) and the ventilation pipe ( 11 ) of the ballast layer ( 12 ) are connected to this.

The plastic sealing membrane ( 15 ) is welded to the sealing tarpaulin ( 6 ) behind the surrounding earth wall ( 8 ) at the pool edge by hand welding ( 16 ) to prevent the ingress of seepage water.

The seal ( 15 ) of the separation and retention basin is protected against damage by abrasion or sharp-edged stones with the known nonwoven mat ( 16 ). A claw mat ( 18 ) is laid over it to stabilize the base cover ( 20 ). A 10 cm thick layer of concrete ( 19 ) is built into the honeycomb-like mat used as formwork to protect against mechanical stress during maintenance work. The embankments are covered with an approximately 10 to 15 cm thick layer of soil ( 20 ) and then planted with greenery.

The pool drain ( 22 ) takes place via perforated pipes ( 24 ), which are covered with filter fabrics and nonwoven fabric and connect to tight pipes ( 25 ). The pipes are mounted halfway down the basin on plastic supports. They can be flowed from all sides, which reduces the flow rate in the pool and thus serves to retain the sludge. This construction can be serviced without much effort and only small amounts of contaminated material have to be disposed of in the event of damage.

Claims (1)

Retention basin, which as a basin without enclosing or lowering the Groundwater is excavated. Over the excavation area is a Sealing tarpaulin pulled and with ballast material made of electric furnace slag spilled. Due to the higher weight of the ballast material and the missing Buoyancy can significantly reduce the required excavation depth. The Waterproofing tarpaulin prevents the entry of groundwater and allows installation the pool seal made of flexible polyethylene sheets in a dry construction pit. For The edges will prevent leachate from entering the electric furnace slag of the two sealing sheets welded to the pool edge. To protect the Sealing membrane against buoyancy, ice, sunlight and mechanical stress a 10 to 15 cm thick cover from the floor and Concrete installed. This will reduce the contaminated excavation quantities after accidents minimized.