Ok, its just another crazy week and I’m running behind, what with one thing and another, but since Metro and the city gave out a bit of information about the leak, I thought I’d look up a little technical info and put it on the blog.

This time, the cause was what amounted to a giant pothole in the making, said Houston Public Works spokesman Wes Johnson.

Workers installing a 12-foot-diameter storm sewer under Hermann Drive at San Jacinto noticed water leaking into the tunnel they were boring, Johnson said. The leak was traced to an 8-inch water line near the rail tracks.

In this picture an 8″ PVC (in service since 2003) water line (in blue) can be seen directly under the intersection, running from a 24″ steel line (in service since 1964). Street edges are in black.

Click for full sized pictures.

The second picture adds sewer line information (in green), and a 7-foot sewer main can be seen under Herman. The 12 foot main under construction is not shown. Street edges have been eliminated from this picture for clarity.

STL means steel line; PVC means PVC (plastic) line; I’m not sure about Cl (CI?) unless it means clay. (Edit: Cast Iron. Thanks to reader Rorschach. Also, I see a ’24″SRC’ which is probably “steel reinforced concrete,” and a 2″ Galv for “galvanized.” 2″C would be “copper.” Thanks to Royko. I was very hurried when I put this post up and it shows.) Generally, steel-reinforced concrete is only used for large water mains because they are very difficult to tap; you pretty much have to know ahead of time where the connections are going to be. Steel, clay, and PVC are much easier to drill through.

(Edit: funky historical note. The original water system, well over a century ago, used 2″ wooden pipes that were hollowed out and flame-sealed. The department thinks that there may still be a few lengths out there in use somewhere, but has no records from that era to be sure! A piece of this pipe is on display in the E.B.Cape center at 4500 Leeland.)

Source: Houston Graphic Information Management System (GIMS), public link. This site supports IE only; it is very slow (don’t click again while a graphic is downloading). The popup menu to the right can be very frustrating, but once you learn to deal with it, there’s lots of information you can get from this source. The ariel photos were taken about four or five years ago though.

Update: Services delayed again today.