When an underground line or structure is abandoned, the two basic options that are considered are (1) abandonment in place, or (2) removal. The removal option is often not feasible or cost-effective.
A structure or pipeline that is abandoned in place without filling may deteriorate and lead to ground subsidence which in turn creates the potential for water erosion, impacting future land use and posing safety issues. It is extremely important these lines be filled if they are located beneath a road, railway or other areas sensitive to subsidence.
Deciding what to fill an abandoned structure with involves a variety of factors such as diameter, length and condition of the structure. Because it is highly flowable and can be pumped over long distances, Geofill cellular concrete is often the material of choice. Another commonly considered material is a sand/cement slurry, however, Geofill LD and Geofill Hybrid have both proven to have significant advantages:
Geofill products are more flowable and will fill the pipe or structure more completely.
Geofill products can be placed with lower pumping pressures which reduces risk of damage to pipe or structure.
Geofill LD requires fewer access points due to the fact that it can be pumped over 5,000 feet while sand/cement slurries are limited to under 500 feet: fewer access points mean lower costs and less disruption.
Every abandonment project involves its own unique set of challenges. Access is to the structure is often limited, requiring the fill material to be pumped long distances . MixOnSite offers a complete solution with its Geofill cellular concrete family products and complete installation services including mix design support, state of the art equipment and experienced crews.
Lower Northwest Interceptor Sacramento, CA
Annular Space Grouting
This project consisted of a 19-mile sewage conveyance pipeline and pump station system that required micro-tunneling methods to install the new lines anywhere pipe could not be installed in an open-cut trench, such as under the Sacramento River or I-80.
The micro-tunneling operation was completed by filling the annular space around the pipe with Geofill LD cellular concrete to prevent corrosion and movement. This flowable material also reduced potential flotation or collapse of the carrier pipe.
