In a Bridge


Well-Known Member
Jun 12, 2001
Potomac River
Once a month we go around to a set of bridges and determine the amount of trash lodged on the upstream side.

Here is what we found inside one of the bridges today.

Judging by the amount of efflorescence and other staining around that joint, corrosion of the reinforcement has or will start soon. Quickly followed by delamination, scaling, and general erosion of the concrete at that joint.

Wait....was I supposed to be looking at the bird debris? I'd get the maintenance guys to remove so it wouldn't affect the bridge rating.

Sorry, used to be a bridge inspector.
This is a picture of the amount of trash that was accumulated at the bridge last August when we began the study. Each month we remove the trash and weigh and inventory it.


This is how it looked this last month. Notice that it is pretty clean and also that there is a plume of turquoise water on the far right.


This is the storm sewer that is discharging the turquoise water. We reported it to Maryland Dept of the Env. and will see if they actually earn their money and do something.

I do not know what was causing it. There is a "Research" facility about a block away and I suspect it comes from them. You will notice that the plants at the outfall are not dead, and the algae in the concrete channel are not dead. There are some daces in the stream and they and the the crayfish were alive. This indicates that it is not highly toxic.

In April there were two preschoolers playing in the water inside the bridge barefooted. Because of the amount of broken beer bottles and the flock of ducks and geese in the stream the kids are at high risk for several types of infections.
It could be an algae itself.

Last year when diesel prices rose so high many people found that algae contained large amounts of oil that could simply be pressed out of it to be turned into biodiesel.

This could be the solid waste from a similar process.

Most of the algae's used were not harmful to humans or animals, in fact many of the commercial biodiesel producers sold the solid waste as a very nutritious animal feed.

Not saying that's what it is, just what it could be. Maybe that's what they are "researching".
This is the response I got from Prince Georges County

Our inspector has visited the site and did not find evidence of the green discharge shown in the pictures. He will continue to monitor to ensure it does not occur again.
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