El K Caster is a maintenance worker for the TriCity Tunnel Authority, currently stationed in Bluffington Beach. Her role there is to maintain the Control Track cleaner robots.
It is heavily implied that she took this job in order to be close to or to continue to investigate the disappearance/current "ghost" state of her friend Olivia, who disappeared due to the Tunnel when they were both fifteen. It is implied that she feels continued guilt over Olivia's fate, as El was always the more adventurous of the two and encouraged Olivia to come with her to explore the Tunnel.
She currently lives in the old Boathouse, presumably to be close to where Olivia can be seen.
In To Be Young Near the Shore, El is described as being in her mid-twenties but "carrying a lot emotionally right now" due to Olivia's disappearance which makes her appear "rougher" or older. She has red hair, and is seen wearing a heavy flannel shirt, overalls, a heavy canvas work jacket, big rubber fishing boots and a knit cap. When seen in Part 4, she is dressed in her TriCity Tunnel Project uniform, which includes a belt with hammers and screwdrivers on it.