Morning Call article identified Andrew Street as the problem, the pipe under Early Street, the other alley between Liberty and Allen, is also undersized. On that street, the manhole covers between 18th and 19th Streets overflow even during a moderate rainfall. The neighborhood and pipes were constructed around 1930, my photograph (click on photo to enlarge) from the late 1920's reveals no houses at that time. I'm afraid that I even have worse news for my friends in the District; Allentown and the surrounding municipalities, rather than make costly improvements to their pipe systems, have been instead insisting that property owners remove their basement floor drains. The floor drains were installed as a safety net, if an inside pipe broke, or something overflowed. Although collectively they contribute only a minuscule amount toward the problem, government would rather have thousands of homeowners spend their money and compromise their safety system, rather than correct the real problem, undersized pipes. Pawlowski and the City recently took credit for the new sidewalks on 19th Street, now let them do a project decades overdue, and fix the storm sewers.
UPDATE: This morning I spoke to a former employee of the engineering department, who confirmed that, indeed, the city has known about this problem for decades. This city's administrators like the ribbon cutting, photo opportunity projects, not the nuts and bolts of maintenance.