Like many cities, Philadelphia has a large percentage of impermeable surfaces (streets, sidewalks, parking lots, rooftops, etc.) that interrupt part of the natural water cycle .  Impervious surfaces  can actually channelize or speed up the natural flow of stormwater.  Many parts of the built environment have a storm drain system — a designed drainage system on the streets that can funnel stormwater into underground pipes that conveys  stormwater to the river or to a treatment plant.

We will explore how designing for the future means creating a more balanced approach to developing a land and water that works with all of the natural water cycle.

In addition to the sanitary sewer system that was designed to collect and convey unsanitary wastewater to a treatment facility, cities like Philadelphia also  built a system of underground pipes on streets to handle stormwater runoff.  Evidence of this drainage system is all around us if you stop to look – called storm drains.  It can be seen in our schoolyard, on our street corners and other places that need the rain to go down “the drain.”

Students will view the videos of a heavy rain storm with water rushing into the storm drain.

Slides 3 and 4:  Videos are linked on the slide deck taken by news meteorologists of recent flooding in neighborhoods in Philadelphia.

Use these videos to spark some discussion about what is happening.

Why might the streets be flooding?

Where is the water going?

What do they notice/wonder?

Slide 5: Show the photos of storm drains in the slide deck

Ask students if they recognize them, and if so, what did they think their function was.

Display a site map of your school area using google maps, including the sidewalk in order to prepare students for this next outdoor portion of the learning experience, which will be a walk around the schoolyard and sidewalk. Students can make a rough sketch of the buildings and areas to help them notate the storm infrastructure they will observe.

Slides 6- 7: Take students outside on a walk around the schoolyard and the sidewalk perimeter of the school with their site map and a pencil. . Clipboards will be helpful if you have them.

This will be like an I Spy game. We are asking students to find evidence of the storm water system in and around their school. Notably they will be looking for the storm drain INLETS . Every corner should have at least one .

Ask students to  draw a symbol to mark them on the map.

During their outdoor observation, use the following prompts as they find them and take note:

Slide 8: Does the storm drain have a medallion attached that says “Drains to the River?” (from the PWD Storm Drain Marking program– save as an action project for later

Is the drain clear or is there litter or leaves blocking the drain ?

If something is blocking the drain, what might  happen during  the next rainstorm?

Added bonus if you can spot any other evidence of water infrastructure outside ( hint: manhole covers; water pipe access…)

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Back in the classroom, share recorded observations

Now introduce the current  day challenges facing the system– one that was designed by Philadelphia and many other older cities nearly a century ago–

One future challenge that we are trying to address is the new types of storms we are experiencing with our  changing climate, that is, more intense rain storms in both quantity and duration. The rain acts like there is a big sponge in the atmosphere that is being heavily squeezed out.

How can we plan for this future?

Long ago, 60 % of the pipes in the  storm drain system in the city of Philadelphia were joined underground to the wastewater system of pipes coming from our buildings. This means that in these pipes called COMBINED SEWERS – the stormwater from the street and the wastewater from our buildings –  join and flow together to be conveyed to the  wastewater treatment plant.  When there is too much stormwater entering the pipe from our storm drains during one of the intense rainstorms,  the pipes – now filled with stormwater and unsanitary wastewater were  designed to overflow into the river. This is referred to as Combined Sewer Overflow.

Slides 9-10 provide a visual diagram of Combined Sewers and is helpful for students to think about the next question:

What could be the problem with this design?

Slide 11: Show the animation

Watch the animation that shows a dry weather day and a wet weather day and discuss

Slide 12: Do they  have any ideas how to help minimize the combined sewer overflow?

End the class by noting that they will soon learn how Philadelphia is meeting this challenge.

Students may design their own storm drain marking using the Storm Drain Marking Program

How many more will they see on their way home from school?

Record observation of the same drain in wet and dry weather conditions