Temporary Helical Pile Support for the 48th Avenue Outfall Project

Project Overview

Construction of a new concrete utility vault along East 48th Avenue created a significant temporary-support challenge. The vault intersected an existing sewer main that needed to remain operational through most of the construction process.

Before excavation began, the project team needed a dependable way to support the sewer main, maintain its elevation and preserve clear access for installation of the vault and its permanent reinforcing system.

Project Challenge

The new vault would encase the existing sewer main. To complete the work, crews needed to suspend the line temporarily while they excavated, installed reinforcing and constructed the concrete vault around it.

The installation sequence played a critical role in the project. Crews needed to establish the temporary support system before excavation exposed the active sewer main. After exposing the line, the project team had to keep it supported and level while workers completed construction beneath and around it.

The project also required a fully removable system so crews could backfill the completed vault without leaving temporary foundation components in place.

MAGNUM Solution

MAGNUM Geo Solutions developed the complete temporary support structure and recommended construction sequence.

Before excavation began, crews installed six MAGNUM® MH939U3-6 helical piles. They equipped each pile with an MHC1300-9P24B2 end cap to support a temporary steel frame above the future vault excavation.

As excavation progressed, crews suspended the existing sewer main from the frame with a series of adjustable straps. Workers could tighten each strap independently, allowing the project team to support the sewer main and maintain its elevation throughout construction.

With the sewer main securely suspended, crews excavated beneath it, installed the permanent reinforcing sleeve and constructed the concrete vault around the existing line.

After completing the vault, crews removed the temporary steel frame and helical piles and backfilled the excavation.

MAGNUM Geo Solutions’ Role

MAGNUM Geo Solutions provided engineering for the complete temporary support structure and developed the recommended sequence for pile installation, excavation, sewer support, vault construction and removal of the temporary system.

This coordinated approach addressed the structural requirements of supporting an active sewer main while allowing construction to proceed beneath and around it.

MAGNUM Products

• Six MAGNUM® MH939U3-6 helical piles
• Six MAGNUM® MHC1300-9P24B2 end caps

Project Advantages

The temporary helical pile support system offered several important advantages:

• Supported the sewer main before excavation
• Maintained the sewer main’s elevation with adjustable straps
• Preserved clear access beneath and around the suspended line
• Allowed the sewer main to remain operational through most of construction
• Provided a fully removable temporary support system
• Supported a coordinated sequence for excavation and vault installation

This project demonstrates how MAGNUM products and MAGNUM Geo Solutions’ technical support work together to address complex utility construction challenges involving active infrastructure and carefully sequenced temporary works.