Underground duct leading from E core to the Boiler House. This was at LG floor level. When it got to the subway, there was a deeper duct that took these pipes below the subway to the Boiler House pump area,
This duct carried heating and hot water (for taps) pipes and also what appears to be a gas pipe as well as electrical wiring. It was originally intended to have chilled water pipes in this duct but they were never installed.