The Wildgrab Valley

When it starts to rain, rainwater collects in the sewer along with wastewater from Hechtsheim, Bretzenheim, and the upper town. This initial surge, also known as a dirty surge, is directed entirely to the wastewater treatment plant for purification.

If it continues to rain, the wastewater is diluted more and more by the rainwater, which is then referred to as mixed water.

This mixed water is now directed into the open, renaturalized Wildgraben canal with the help of various weirs. Thanks to its winding shape and natural substrate (limestone boulders), the water has plenty of space here and can seep away and evaporate. This is important for the Earth's natural water cycle.

If the rain continues and more and more water arrives, it can be temporarily stored at the three barrages. From there, it is allowed to flow on little by little and reaches a settling basin. Here, dirt and mud, which are heavier than water, settle. From the settling basin, the water then flows into the rainwater retention basin. Here, the water can evaporate and seep away again, thus returning to the natural water cycle.

Incidentally, toilet paper residues and similar items do not normally even reach the rainwater retention basin. Floating baffle walls (picture below), i.e., walls that are always at the current water level, hold them back before they reach the three barrages.

However, more and more people are mistakenly using their toilets as trash cans. Food scraps, wet wipes, paint, cotton swabs, or cigarette butts cause screens to clog or floating baffles to be washed over. When a thunderstorm hits, fecal matter and toilet paper can also overcome the barriers and be carried by the floodwaters to places where they shouldn't be, such as the rainwater retention basin.

New habitats have been created thanks to the environmentally friendly design and landscaping of the wildlife ditch.

When the Wildgraben ditch is dry, you can see limestone boulders typical of the landscape. Plants that cope very well with varying water levels have settled on the bed of the watercourse.

From May to September, the bright yellow marsh iris blooms here. Please do not pick them, as all parts of the plant are poisonous and specially protected under federal nature conservation regulations. From June to July, you can see the pink flowers of the reed canary grass.  From a distance, it looks like reeds, but it belongs to the sweet grass family. Also found here: meadowsweet, purple loosestrife, and marsh marigolds.

The shore area transitions into a sage-smooth oat meadow. Goldfinches, chaffinches, and butterflies such as swallowtails and large blue butterflies, various grasshopper species, and dragonflies particularly appreciate the rich food supply in the Wildgrabental valley.

The renaturation of the valley is remarkable: where a concrete drainage channel once ran straight through the valley, a natural-looking stream now meanders its way through.

Pools of water reflect the sunlight, and small and large boulders offer additional variety for the eye, which otherwise wanders over meadows and fields.

The area between the old brickworks site, the toboggan hill, and the A 60 motorway is not very large. And yet, thanks to the redesign, it has been possible to respond to floods such as those in 2006 or very heavy rainfall such as in 2008.

The valley is a boon for nature. Birds, butterflies, dragonflies, and other insects find food and shelter here. Walkers also greatly appreciate the Wildgrabental valley.

But always remember that what looks like a small idyllic stream or lake is actually an open sewer. You should never swim in it.