LEADER OF POLISH ECOLOGY
In December 2003, for elaboration of technical documentation "Relief channel - flood protection of the City of Opole", "Hydroprojekt" has been awarded with the title of "POLISH ECOLOGY LEADER" in the 7th edition of the competition for the prize of Minister of Environment in category of products, subcategory - facilities for environmental protection.
Award ceremony
Flood relief channel, situated in the ancient Odra River valley in Opole, had been constructed, with several interruptions, since 1935. The first stage of development, with embankments on the whole length of channel but for limited flood capacity, was finalized in 1978. Completion of the investment as the largest and the most important undertaking in the field of flood protection improvement in Opole has not been determined until after catastrophic flood in July 1997 and humongous damages related to it.
City of Opole map
The undertaking, initiated in 1998 by Regional Water Management Authorities in Wroclaw, was completed in July 2002. Technical documentation has been elaborated by "Hydroprojekt", "Energopol 7" - Poznan S.A. (currently "MAXER S.A. Poznan) performed the function of general contractor of the construction works, Regional Water Management Authorities performed construction supervision and "Hydroprojekt" site supervision on behalf of the Consultant.
The completed investment received high technical evaluation of the experts, as well as the local population. Achieved technical effect concludes: enlargement of the flood capacity of the Opole water junction, covering the Odra River, Relief Channel and Mlynowka, from 2100 cu m/s in 1997 up to 2760 cu m/s currently (flood capacity of the channel itself has been increased from 600 cu m/s up to 1600 cu m /s). Investment ensures also regulation and acceleration of the flood waves through the Opole water junction as well as full protection of the S/W quarters of Opole along with Zaodrze against flows not exceeding max probable water level.
At the same time, conditions for further improvement of flood protection for Opole downtown and quarters in the closest neighborhood, have been created. Additional protection is also closing Mlynowka for flood waves. In the future, construction of polder Opole with 20 mln cu m capacity will ensure slowing down the flood wave and creation new possibilities for water retention.
Investment has been conducted in difficult conditions from the point of view of environmental protection, resulting from the character of the river valley. "Hydroprojekt" elaborated technical solutions, allowing to minimize the negative impact of the investment on the environment. Designing new structures or modernization of the existing objects on the Relief Channel, solutions appropriate not only due to the technical reasons, but also environment friendly.
As a result of the application of this activities, all significant natural habitats in the endangered area have been protected. Special care has been given to the renaturisation of the river valley and restitution of the endangered biotopes.
Presented undertaking may be an example of excellent co-operation of the natural scientists, administrator of the river, designers and contractors, proving that the compromise between demand for investments and environmental protection is possible to reach and brings outstanding results.
MAJOR STRUCTURES OF THE INVESTMENT: Flap weir with road bridge in the inlet part of the Relief Channel.
Weir ensures safe passage of waters through the channel bed and regulation of the maximum water level on the Opole barrage with movable steel flaps for navigation purposes. Water, dammed up by the weir overflows the flaps and falls downstream of the channel. This way water becomes well aerated, also during the winter
Technological equipment of the weir and flap heating system ensure proper exploitation of the weir even at a big freeze. Closing and raising flaps, as required for exploitation purposes, is not laborious as they are operated with hydraulic drives, controlled automatically from central computer. Flap weir has been equipped in appliances for automatic measurements and transmission of information regarding water level upstream and downstream the weir. The system is fail-safe even without power supply for the weir, as it works using solar battery with set of secondary batteries, installed on the roof of the control room.
During flood, system ensures constant transmission of information about current water levels, using GSM and satellite communications. Inhabitants of Opole may also obtain data on water levels thanks to cable communication. (Station no. 77-457 22 03).
Road bridge over the weir protects, even during the flood, communication with Bolko Isle with zoological garden and large park, being the natural monument. Before construction of the bridge access to the Bolko Isle by car was during the flood virtually impossible, what made evacuation of the ZOO animals very difficult and caused severe casualties in 1997. 
Weir - upstream view
Embankments
Existing levees were heightened, widened and water tightened with Bentofix mats, made out of geo-membrane and bentonite.
On the embankments crests 2 m wide walkways made out of mineral mix and technological roads along the levees for their control during flood were designed. These roads are used mainly as bicycle lane.
New embankments were constructed in the inlet part (right embankment - 750 m long) among other reasons, for gaining additional grounds for new park area of "Bolko Isle" and to adapt ground excavations for additional small ponds.
Additionally flood protection embankments were created in the outlet part of the channel (right embankment 380 m long) for connection with existing embankment of the Odra River to protect municipal biological treatment plant in Opole. All surfaces of the Relief Channel embankments, excluding walkways and technological roads were covered with 20 cm of fertile soil and planted with mix of grass.
Channel bed
On the existing, as well as on the new constructed reach of the channel bed, protection of the slope with stone rip-rap (50 cm thick coat) has been laid on the needle geo-membrane G=400g/sq. m. Stone rip-rap above water level has been coated with fertile soil and planted with the mix of grass. Thanks to such solution construction of the channel bed has become invisible.
In the area of the railway bridge in 2,67 km of the Relief Channel, in reference to the modernisation of the bridge pillars, bottom and the slopes of the channel bed have been secured with gabions 50 cm thick, placed on two coats of geomembrane, as described above. Also grounds between channel embankments under the bridge has been protected with 30 cm thick gabions on geomembrane. Al gabions on the slopes above water level and between channel embankments have been coated with fertile soil and planted with the mix of grass. 
Opole - aerial view
Area at the foot of embankments
Taking into consideration conditions proposed by nature scientists, in many places the area at the foot of channel embankments have been preserved in its natural form. All large sandbars and gravel areas created in natural way have been saved. Many new one have been created. They enrich the mosaic landscape and variety of ecological niches for plants and animals.
Area at the top of embankments
Within biotope renaturisation of the Odra River valley, there have been created numerous, shallow water reservoirs, in which regeneration of the rushes and other aquatic plants, as well as several kinds of amphibians and insects related to water biotopes, are observed. The largest of them, of over one hektar surface, being along with vast sandbar a part of excavation area set in order is situated on the left side at the inlet part of the Relief Channel. On the right side of the inlet part of the Relief Channel, 3 smaller water ponds along with sandbars, have been preserved.
Fragments of the ground at the foot of embankments have been lowered down to the level allowing development of the alluvial plants (almost extinct in Poland), forming low terraces. In the hollows of the ground numerous rushes, bushes and tussocks have been preserved. The most of natural habitats have been saved at the foot of embankments and in the Odra River valley downstream the outlet of the Relief Channel, by leaving fragments of the old riverbed, rushes, bushes and trees areas untouched. Also in the areas at the foot of embankments of the Odra River, upstream the outlet of the Relief Channel, water ponds left after partially filled ground excavations used for embankments modernization, have been kept.
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