Context

In 2019, one of the main sewer pipes in the Lima, Peru district of San Juan Lurigancho failed. The expansion of the Metro system likely caused excessive vibrations, which, combined with static load, created stress in the pipe and the failure. Sewer water spilled into the streets and surrounding areas and affected potable water access to half a million people. Learn more in this HDPE pipe case study.

Opportunities

The city’s requirements posed significant challenges. First, the design had to resist the forces that caused the previous pipe to fail.

Second, the sewer pipe had to maintain its strength and structural integrity throughout its service life, which meant the pipe required a protective layer for corrosive resistance. Typical sewer piping materials like cast iron can corrode through various processes such as microbial-induced corrosion (MIC). Corrosion can also negatively impact flow capacity, which can cause a strain on the district’s stormwater and anti-flooding measures.

Third, the replacement pipe was for a large-diameter sewer main in the middle of an inhabited district, necessitating a low-impact installation method. Going completely trenchless was not an option as the engineers sought to construct a tunnel around the sewer pipe for reinforcement. Finally, public pressure and international coverage of the sewer spillage meant prompt project completion.

High-density polyethylene (HDPE) is an ideal sewer piping material that meets all project requirements. However, no one had ever installed an HDPE sewer system at this scale and under these circumstances.

Solution

AGRU presented a solution with its AGRULINE system, which comprises solid-wall extruded orange pipes with OD 1600 mm SDR 26. The HDPE pipes made with PE 100-RC offer superior durability, longevity, and stress crack resistance and are near-impervious to most chemical and biological fouling. The pipe’s characteristics meant requiring far less maintenance than other piping materials and ensuring high flow capacity throughout its service life.

The AGRULINE system solution included the pipes, electrofusion couplers, electrofusion machines, engineering support, special installation tooling, and training. Project engineers utilized AGRU’s expertise for an installation concept that married the location’s unique challenges with the project’s requirements.

AGRU presented an installation plan that involved electrofusion welding in situ using specialized tooling designed for this project to minimize the sewer pipe’s installation footprint. To prevent vibrational forces from affecting its new pipe, engineers first built a metal tunnel that would offer structural support and encase the sewer pipe. Installers filled the space between pipe and tunnel with concrete. The total working area for installation was about 5.6 m in diameter and 10 m below the ground level.

Outcome

AGRU supplied, trained, and supervised the installation of 380 m of 5-m pipe segments using 76 x 1600mm electrofusion couplers. These pipe segments were custom sized to facilitate installation. The welding sequence designed by AGRU supported parallel welds, which reduced installation time by half. AGRU also provided quality assurance assistance and customized software alongside the welding equipment to minimize errors.

“We are proud to have been selected as a partner by QSI and SEDAPAL,” says Edgardo Cornejo, chief operations officer at AGRU. “Our AGRULINE solution continues breaking records thanks to massive efforts within our organization to push the limits of our products and ingenuity.”

The installation was certified and completed in 2021. Contact us to learn more about this HDPE pipe case study and how we can help on your next project.