Water ingress at Forest Glen

I was at Forest Glen on Saturday and I noticed that the southbound platform head wall and tunnel have been badly affected by water ingress. The concrete is completely soaked through with water and there were mineral deposits and moss/fungi growing on the walls. The ingress was so strong that I could hear water rushing through the tunnel sump drains, even though it wasn't raining at the time.

Given the depth of the station here, is this water ingress from blocked/damaged roadway/sanitary sewers overflowing into the Metrorail vent shafts, or is it more likely to be underground aquifers or streams within the water table overflowing into the tunnel sumps and vents? I don't know very much about the geology of Montgomery County near the Beltway so I'm interested to know more about how water ingress starts within the Metrorail system.

This reminds me of the Woodley Park stop, where the water infiltration is also very, very bad. There is not just moss growing but small plants as well (if I recall) along the walls near the lights. This would seem to be a pretty bad electrocution risk to workers if/when they work in this area.

Woodley Park-Zoo like the other stations on the Shady Grove end of the Red line north of Farragut North have no water proofing beyond the poured in place concrete tunnel linings and shotcrete station cavern linings. On the Glenmont end the station caverns and tunnels have a water proof membrane outside of the concrete lining similar to the water proof membrane in the tunnels between the Tysons Corner and Greensboro station.

To my knowledge there has always been seepage flowing through drains in the Forest Glen station. As I recall the water proofing membrane on the Glenmont end diverts the seepage to the drains as apposed to blocking its penetration.

The vent shaft surface opening at the Forest Glen station are located such that runoff cannot enter the openings. The north vent shaft surface opening is on the northwest corner of Forest Glen Road and Georgia Avenue, the south vent shaft surface opening is inside of the northwest corner of Capitol Beltway Georgia Avenue interchange next to pedestrian bridge.