This is actually a case study for a residential elevator pit that was being put in by a high-end builder/remodeler in Newton, MA. He had put in a home addition behind where he had put in the elevator pit, which is slightly below the basement. He told me it was leaking where the floor of the elevator pit meets the foundation.
We went in and injected a polymer resin by drilling into the seam, putting our ports in, and injecting the polymer resin. Everything was good. Then we got some very heavy rain and it was leaking again. We went over there next time it was raining, and it was actually not leaking from where we injected, but from about 4" or 5" higher where there was no crack. We had stopped the water from coming in at that seam but there were small fissure cracks that the water found it's way to. As it was coming through, you could see more little areas where the water was coming out. This means that the concrete was either too watery or was not vibrated enough to let these little fissures out. I also found out that there is ledge right behind the pit. This could mean that the concrete may not be very thick.
To address this, we used a crystalized quartz material that penetrates the concrete and then grows microscopically in the pours of the concrete to stop the water.