Egg-cellent Upgrades

Egg-shaped GRP pipes used for major sewer rehab in Bucharest.

Limited space and accessibility at the construction site in Bucharest's city center.
Limited space and accessibility at the construction site in Bucharest's city center.

ROMANIA, JULY 22, 2019 -- The sewer system of Romania’s capital Bucharest is between 25 and 100 years old. It was decided to renovate the system step by step in order to increase its efficiency and reliability. One of the sections to be rehabilitated is particularly challenging: near the Parliament house and old town, where space and accessibility are limited. Conditions that called for a special approach – and the perfect solution was found with Amiblu. After thorough technical considerations, a contract was signed over the supply of 5200 m egg-shaped non-circular GRP pipe profiles in a range of cross-sections. Within almost two years, six out of seven sections of the aged sewer were successfully relined with Amiblu NC Line pipes – each with profiles of a different width (780-1700 mm), height (1200-2550 mm), and wall thickness (14-24 mm). The seventh and last part is currently being supplied and shall be installed by end of 2019. Another 63 m of circular Hobas GRP sewer pipes were also installed via relining. Once finished, the rehabilitation project will improve environmental protection as well as the safety of Bucharest’s water and sewer system and reduce its overall operating costs considerably.

Costin Berbecaru, Amiblu Sales Director for South-East Europe, talks about the complexity of the project.

A low-impact trenchless installation: The relining process hardly affected the traffic flow around the construction sites.A low-impact trenchless installation: The relining process hardly affected the traffic flow around the construction sites.

Let us start at the very beginning: What’s the background of this project?
Berbecaru:
The sewer rehabilitation in Bucharest involves a number of stages and locations. In April 2016, TAHAL and Bucharest City signed a contract for the implementation of different works. These include a shotcrete rehabilitation section, the sealing of joints, a microtunneling installation of a new collector, and the rehabilitation through GRP relining over a length of almost five kilometers. For this last section, TAHAL initially had a different pipe supplier in mind, but in the end we totally convinced them of the benefits of Amiblu GRP: The established brand and quality, best quality-price ratio, availability of our full knowhow and experience, and the flexibility with which we were able to adapt the pace of deliveries to their needs. The supply contract was signed in November 2016. The first order for half of the project was supplied in December 2017, the second in September 2018, and a 3rd and 4th order followed.

Which preparatory work was done by Amiblu?
Berbecaru: Our experts team performed several tests and FEM calculations, created reports and procedures, in order to perfectly customize the non-circular profiles to the existing channel’s varying diameters and conditions. The pipes’ wall thickness, for example, was defined and calculated according to the project load using the 3R2014 and ISO 16611 method. The NC product offers an equal or even greater equal vertical deformation resistance compared to a SN 10,000 circular pipe of the same height.

How were the pipes transported to the construction sites?
Berbecaru:
The pipes were delivered to the different locations right in the heart of Bucharest on smaller trucks which were equipped with cranes. This way we could optimally adapt to the narrow streets and heavy traffic as well as the restricted possibilities for unloading and storing the pipes on site. Our Amiblu project teams are perfectly at ease with such challenging logistics and site conditions since many trenchless projects are realized in urban areas.

That’s certainly a huge benefit! So, the pipes were then inserted into the old channel?
Berbecaru: Exactly. Both the NC profiles and circular pipes were lowered into the old brick sewer through a shaft with a crane or forklift and then either moved horizontally by a trolley or pulled with a steel rope by a crane from the opposite side. The single pipe segments of the same dimension were joined through bell-and-spigot joints with elastomeric gaskets with the support of the working staff, who helped to perfectly adjust the position of the profiles. Differently shaped sections were connected via manholes, after centering and fixing the pipes by means of spacers of different materials. Depending on the weight, position, and dimension of the pipes, the necessary force of connection was provided either by forklift, hoist, or manual tools. The new pipes were then fixed inside the aged channel with an innovative method of welding bolts and nuts into each pipe, on minimum four and maximum eight points, which results in a strong fixation between old and new pipe.

Amiblu NC Line pipes make the old channel as good as new.

Any notable implications of the installation works on traffic and Bucharest’s inhabitants?
Berbecaru: Nothing considerable, not even during grouting, which is the installation phase that requires most machinery – compressor, mortar truck, mortar pump, water tank, etc. – and space. We completed 90 percent of grouting works at nighttime so to not disturb the traffic.

How about the remaining parts of this large rehabilitation initiative?
Berbecaru:
There’s still a lot of work to be done and Amiblu has been involved from a very early stage. Bucharest is currently preparing a documentation to access EU funds through the POIM program (operational program for large infrastructure). Another project is currently in preparation, which involves rehab measures with both circular and NC pipes of the sewer network in three districts: Cotroceni, Regina Maria, and Tineretului. After completion of this project, the client is very satisfied with our professional approach and interested in maintaining the partnership for further stages.

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