Repair of the Dražica wastewater outfall
One of our current untypical projects is located in the Kraljevica harbor, which is the Dražica wastewater outfall and it stretches from the seacoast wall to the center of the Kraljevica harbor towards the west.
The outfall pipe is completely underneath the sea level, and the outfall ends at a depth of approximately 13.00 meters under water, with a total length of 65.00 m.
A concrete covering of the pipeline is done along the entire length of the outfall and is in extremely poor condition due to the numerous holes/cracks found on the concrete joints, tilted substrate sections, broken part of the substrates, larger surfaces of unstable concrete on complete sections and on certain parts of the outfall, the thickness of the substrate is greatly reduced.
Based on the above mentioned facts, the integrity of the substrate, as well as the condition of the pipeline within the substrate, is questionable. Due to this, the following is required:
– replace the existing pipe with a new one
– completely repair or remove the existing substrate
– create a new compact substrate with a protective stone to prevent damage from the waves of the sea
– remove existing concrete substrate, including the existing outfall pipes
After the removal of the pipes and substrates, it is necessary to excavate material for the reinforced concrete wastewater outfall, and after the excavation it is necessary to plan the bottom of the channel with the pipelines and laying the PE pipes with a nominal diameter of DN 710.
On the laid pipe, it is necessary to install reinforced anchor at every 4 m ‘and make the sheeting for the concrete substrate of the outfall.
The concrete sheeting is made concrete grade pressure strength of C 25/30 and along the concrete sheeting there is filling performed around the part of the outfall buried in the sea bottom in the width of 30 cm. The embankment made wider than the sides of the outfall to the level of the top of the outfall.
In addition to the execution of the outfall, a new reinforced shaft is also foreseen at the site of the existing outfall shaft.
After the executed work related to the outfall, it will be necessary to remove the old window and perform a connection of the existing canalization pipes on the newly-built shaft.
Upon completion of the works, a pipeline waterproofing test will be performed and a newly created outfall video will be produced.
