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Calculating Rainwater in a School Yard

Learning Experience 3

Big Ideas

When it rains, the water has to go somewhere. Even a small amount of rain over a wide area can add up to be a significant volume.In order to manage stormwater runoff and in order to keep our cities safe, we need to know how much rain we are expecting and how to manage it. Impervious surfaces will increase the significance of each rain event as runoff is increased.

Summary

When it rains, the water has to go somewhere. Even a small amount of rain over a wide area can add up to be a significant volume. In order to manage stormwater runoff and in order to keep our cities safe, we need to know how much rain we are expecting and how to manage it.

Engage

Students will complete a number of activities to understand the volume of water that is managed by a sewer system.
This  activity will allow students to fill a cubic foot box or container with water to determine what volume of water is in a cubic foot.

Approximately 7.5 gallons of water will be needed to fill the cubic foot.

Bregy Schoolyard Example

Put students in groups of 4-5 around the Bregy Aerial School Yard Map. Explain that students are looking at a “bird’s eye view”. Discuss what can be seen on the map. Describe the surfaces (impervious or pervious.).

Schoolyard Measure

Divide your school yard (or other easily accessible area) into sections. Have teams of students measure the length and width of their area to calculate the square footage.

Back in the classroom use the length and width to calculate the cubic foot measurement using 0.083 as the height value.  0.083 is one inch represented as a fraction of a foot.

This will give us an approximation of the volume of water in their section of the schoolyard.

If you are not able to measure a room or other outdoor space, use desk or table tops.

This is an important concept for students to understand. The weather reports that x inches of rain fell, but understanding the volume of water that represents is critical.

Students can use this calculation worksheet to help guide the measurement.

Explore and Explain

Students will use an actual schoolyard map to calculate the volume of water falling in a 1 inch storm to set the context for water runoff management.

How to manage the water: Green Infrastructure Tools

After the students complete the rainwater calculations, ask students to use the GSI cards to help capture rainwater on the site.

If students are interested explore how Green Tools are protecting Philadelphia’s Waterways using the link below.

How green tools protect Philly’s waterways from Philadelphia Water Department on Vimeo.

View How Green Tools Protect Philadelphia’s Waterways below then make a list as a class..

How green tools protect Philly’s waterways from Philadelphia Water Department on Vimeo.

Elaborate

Ask students to explore the Philadelphia Water Department’s  Big Green Map Virtual Tour  and Stroud Water Research Center’s  Wikiwatersheds  to become familiar with different GSI (BMP) strategies.

Is there Green Stormwater Infrastructure in the neighborhood near your school?

Discuss what other improvements help manage polluted stormwater and improve and restore ecological health to our waterways such as wastewater treatment plant expansion or upgrades; stream bank restoration project; other ecological services—such as living shorelines and restoring freshwater mussels to our waterways to help keep them clean.

Extensions

Go outside and examine the school yard. Does the school yard appear to have more or less impervious surface than Bregy? Predict whether Run-Off Flow will be lower, higher, and/or comparable to Bregy. Using a ball to determine elevation changes could also be helpful. Use contour lines on the schoolyard map to help determine elevation.

Invite a PWD engineer to discuss calculations with class.

Teacher Support

Essential Question:

How can we create a healthy, beautiful, and sustainable Philadelphia for everyone?

Guiding Questions:

Engage

How many gallons of water fall when we have an inch of rain?
How can we calculate the volume of rainwater that needs to be managed?
How much water does a cubic foot hold?

Explore and Explain

What are the best designs to capture and absorb water in different places?
What are the tools they are using that make up green infrastructure to manage the amount of water we need to manage?

Students will be able to:

Estimate how many gallons of water they think will fall in the school yard when we get an inch of rain.
Calculate the volume of rainwater that needs to be managed (lesson in 5.2) (start with a generic schoolyard and then theirs if possible) in order to determine what types of green infrastructure tools are best for their school location.

Ruler
Cubic Foot Box

Laminated Bregy School Site Plans (Link to the Site Plan to print out)

Laminated School Yard Map (Request specific map  from FWW or print from Google Earth)
Green Schools Infrastructure cards
Calculating Stormwater Runoff PDF

Calculators

Rulers

Pencils

Roll of tracing paper

Tape

BASIC TERMS
Cistern noun
A tank for storing water

Combined Sewer System noun
A sewer system that carries both sewage and storm-water runoff. Normally, its entire flow goes to a waste treatment plant, but during a heavy storm, the volume of water may be so great as to cause overflows of untreated mixtures of storm water and sewage into receiving waters. Storm-water runoff may also carry toxic chemicals from industrial areas or streets into the sewer system.

Evaporation noun
The movement of free water molecules away from a wet surface into air that is less than saturated; the phase change of water to water vapor.

Green Roof noun
A roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.

Impervious adjective
A hard surface area that either prevents or slows the entry of water into a soil as under natural conditions prior to development

Infiltration noun
The penetration of water into sub-surface soil or the penetration of water from the soil into sewer or pipes through defective joints, connections, or manhole walls.

Pervious/Permeable noun
Surfaces that allow the penetration of water into the ground.

Porous Pavement noun
Pavement that allows stormwater and snowmelt to pass through the voids in the paved surface and infiltrate into the sub-base.

Potable adjective
Water that is safe for drinking and cooking.

Precipitation noun
Rain, snow, sleet, and hail- the moisture supply….

Rain Garden noun
A planted depression or a hole that allows rainwater runoff from impervious urban areas, like roofs, driveways, walkways, parking lots and compacted lawn areas, the opportunity to be absorbed.

Sanitary Sewer noun
Underground pipes that carry off only domestic or industrial waste, not stormwater.

Storm Sewer noun
A system of pipes (separate from sanitary sewers) that carries water runoff from buildings and land surfaces.

Transpiration noun
The process by which water vapor is lost to the atmosphere from living plants.

ADVANCED TERMS
Infiltration Basin noun
A type of best management practice that is used to manage stormwater run-off, prevent flooding and downstream erosion and improve water quality in an adjacent body of water.

Membrane noun
A thin soft pliable sheet or layer.

Mitigationnoun
Measures taken to reduce adverse impacts on the environment.

Percolation noun
The movement of water downward and radially (and sometimes upward) through subsurface soil layers, usually continuing downward to ground water.

Stormwater Tree Trench noun
A system of trees that are connected by an underground infiltration structure. On the surface, a stormwater tree trench looks just like a series of street tree pits. However, under the sidewalk, there is an engineered system to manage the incoming runoff.

Swale/Bioswale noun
A long, gently sloped, vegetated ditch designed to filter pollutants from stormwater.

Vegetated Filter Strip
noun
A defined area covered with plants designed to remove pollutants and sediment from runoff water via particle settling, water infiltration, and nutrient uptake.

Velocity Dissipater noun
Any device designed to protect downstream areas from erosion by reducing the velocity of flow.

Estimate how many gallons of water they think will fall in the school yard when we get an inch of rain.

Calculate the volume of rainwater that needs to be managed (start with the Bregy schoolyard and then theirs if possible) in order to determine what types of green infrastructure tools are best for the school yard.

PA STEELS Standards

Environmental Literacy and Sustainability

3.4.6-8.H Sustainability and Stewardship: Design a solution to an environmental issue in which individuals and societies can engage as stewards of the environment.

Student Materials

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