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Ashkelon Wastewater Project

water authorities project
Engineer Mr. David Yaloz at construction site

Israel is known as the land of the Bible, but it is actually much more than that. Israel is a modern, developed country located along the Mediterranean Sea.

Due to the long, hot and dry summers with very short rainy winters, water becomes one of the most important issues in the country. Therefore, as one of the most arid environments on earth, the available water system has to be handled and developed very carefully.

On this basis, the Water Authority approached the engineer Mr. David Yaloz with the task of finding the most suitable piping system to enlarge and replace an existing wastewater system in the town of Ashkelon. The existing pipeline is constructed from a 48” asbestos cement pipe. The new 3.6 km pipeline will replace the existing pipe and a further 3.6 km pipe will be laid after the existing pipe is decommissioned to provide additional capacity and flexibility for this expanding town. The Israeli pipe market offers many different pipe materials i.e concrete, HDPE, PP, steel, and PVC etc. for a sewer pipeline project like this.

Existing specifications and data sheets of various pipe manufacturers were compared with the project requirements until the most efficient piping system was identified. Furthermore the project required that the pipes should be in accordance with applicable international standards.

The pipeline will be installed at a depth of up to 6 meters.  Groundwater levels could be higher than the level of the pipe therefore the piping system must be leak-tight. The customer requires a long service life without any leaks or failures.
If the pipe system leaks, infiltration and exfiltration can cause damage to the piping system and the environment. In this case infiltration was the main concern of the customer which could occur due to defective pipe joints or broken pipes.

Considering these issues, High Density Polyethylene (HDPE) became the best choice for the engineer and the customer. The material is flexible, impact resistant, has excellent hydraulic, abrasion and corrosion resistance and is much lighter when compared to traditional rigid pipe materials. The physical properties and material characteristics fit in perfectly with the requirements of the customer. Therefore the decision was made to use DN/ID 1500 mm sized High Density Polyethylene pipe and according to the soil conditions the required ring stiffness was determined as SN8 according ISO9969.  A further question and the most important issue was to clarify which type of jointing will prevent any pipe failures or disconnection. Traditional rubber ring sealing is leak-tight when installed correctly, but due to soil movement the pipe can be disconnected and it does not create a homogenous piping system.  

As the most experienced pipe manufacturer in Israel, Plassim recommended the use of HDPE Krah Pipe with integrated electro-fusion joints according to the DVS2207 standard. The electro-fusion socket is one of the most efficient techniques for jointing of large bore pipes from polyethylene. This type of connection is rightly considered to create an absolutely leak-tight joint which assures a completely homogenous piping system with a long service life of at least 100 years.

Electrofusion joint carried out on a Krah pipe
Electrofusion joint carried
out on a Krah pipe
Tightness test on a Krah pipe
Tightness test on a Krah pipe

A further issue was to define the right “HDPE” material. HDPE has many grades which can also include undefined types of recycled material. Poor quality material can cause poor quality fusion therefore we recommended using PE100 virgin material. This was not specified in the tender but provides superior fusion quality and added value to the customer.  

The installation of the first Krah Pipes began in March in Ashkelon together with
Krah’s application engineer from Germany Eng. Mr Jochen Blickheuser. The leak-tightness of each of the fused joints was tested according to DIN EN 1610 using a special test rig prior to backfilling the pipes. The project is still ongoing with great success.

Plassim is proud to manufacture and deliver the superior leak-free Krah piping system especially due to the importance of water and sewage conveyance in our arid country.

mr gadi yahav

Author:
Mr. Eng. Gadi Yahav
Plassim Infrastructures Ltd.