Building on the students’ understanding of natural watersheds, they learned in the previous learning experience that relying on existing streams as a drainage system  was not sustainable.

With Philadelphia’s exploding population during the industrial era came increased waste.  The waterways used for drainage were becoming  open sewers — and  unsustainable. The  solution? Bury the streams in pipes , fill in around and above and develop the land for homes and more.  Encapsulating  streams into pipes created the sewer infrastructure we rely to this day to carry, convey and make our flush go away.  That is why we can’t see any of the original natural streams in the older parts of the city —  streetscape replaced landscape. Now we see the seemingly endless blocks of  2 and 3-story row homes that have come to characterize Philadelphia.

Slide 3:

What do we know, or think we know, about the sewer system in Philadelphia?

Why did cities choose to bury their  wastewater pipes deep underground?

Is there any visible evidence of this system ?  How do we know it’s there? 

Ask students to share with each other any ideas they have about Philadelphia’s sewer system. Perhaps they never even thought about it!  After gathering their thoughts, watch the video linked below and in  the slide deck on Slide 4 to take them on a tour of a sewer system.

Hidden Sewers video

By the late 1800s , many cities managed their unsanitary waste by collecting it in an underground pipe system.

We can see evidence of this system, some in plain sight  (e.g. toilets, manholes on the street, during construction on our street)

Ask students to recall the the upstream- downstream activity we did in the beginning of this Unit .

Slide 5-6 shows a map of Philadelphia’s creeks and streams before Europeans arrived as an extensive part of the landscape with naturally occurring hills and valleys.

As we saw in the previous learning experience, the vast networks of Philadelphia’s natural streams were increasingly being used for  dumping waste – using them to drain the pollution away (out of sight out of mind?)  These smaller creeks and streams emptied out into the larger river that was also the source of Philadelphia’s drinking water. What a mess!  It eventually made people  gravely sick.

Slide 7 shows a map of the streams that we can still see on the surface.

Slide 8 shows the sewer pipes into which the streams were encapsulated.

Slide 9: Both maps are shown side by side so that students can see how the sewer lines were built over many of the stream lines.

The maps we just viewed showed us where the streams are hiding across the entire city. Let’s take a  closer look at how the land around your schoolyard has changed.

This can be done in small groups or the teacher showing the map views to the whole class.

To view a historical map of your school  visit:  https://www.philageohistory.org/tiles/viewer/

A stepper for using this map viewer can be found HERE.

Have students suggest evidence of the hidden streams  under the school yard or around the school. If a walk around the schoolyard or neighborhood is not possible, have students note evidence on their way home from or to school.  Some examples of evidence might be: manhole covers (which provide access to the sewer pipes below; sink holes, curvy streets that might have followed a stream;

If students suggest storm drains, make a note of that evidence which will be explored later.

Stories from underground

If your students want to explore first hand what sewers are like,  use the links that describe what its like to “go down under.” The article  “Down Under Tales” describes what it was like to inspect sewers. Today much of the inspections are done with robots and cameras —

Ask your students–

Would you like to be a sewer inspector?

Down Under Tales from the City Sewer System

Sewer Photographs