Our crews install, repair, remove, reroute and even rebuild electrical cables every day as an essential part of maintaining and upgrading the electrical grid. This results in over 1,000 tons of used cable each year.
We were faced with a literal pile of problems with all the used cable from underground replacement efforts, overhead work and substation control rooms. What could we do with all the cable?
Reducing waste
As part of our 2035 sustainability goals, we are committed to recycling, reusing and repurposing operational waste materials to keep them out of landfills. We plan to divert 75% of our waste and achieve zero waste in 2050. We already had a solution for extracting and recycling the aluminum, copper and scrap steel from the plastic jacketing of the cables, but we were still left with 540 tons of plastic material known as cross-linked polyethylene (XLPE).
This is a type of material that cannot be melted down or recycled and therefore ends up in the landfill. We wanted to change this, so we partnered with the SMART (Sustainable Materials and Recycling Technologies) Laboratory at the University of Arizona (UA) during the 2021-2022 school year to help us explore different options.
Research and testing
The UA lab did a study that replaced the normal materials in concrete with the XLPE waste from our cables. The UA team’s initial findings indicate that XLPE not only improved the workability and air content of fresh concrete but also strengthened the concrete when being formed into specific shapes such as slopes and stairs.
The new concrete could be a great choice for lining irrigation canals because of its strength and resistance to cracking. We will continue funding the research through this partnership to evaluate the long-term performance and durability of the product and its other potential uses. In addition, the team has also started testing the addition of XLPE to backfill slurry mixes used for excavation work.