Rain Gardens & Water Pollution

Essential Question
How can inclusion of green space in urban areas decrease nonpoint pollution? When/where is which solution appropriate?

Objectives

 * Explain how different solutions reduce energy usage and pollution.
 * Employ knowledge of pros and cons of different solutions to pick one that is appropriate for their city
 * Explain how green infrastructure models a natural environment
 * Predict how different materials will filter runoff and model a natural environment.

Introduction & Student Background
In many urban areas (cities, towns) there is not enough plant life to address various environmental problems. Some of these include erosion (when soil and rocks are swept away by natural processes, which could damage the foundation of buildings), heat island effect/heat stress (Raised temperatures a health risk, especially for vulnerable groups (e.g. elderly, very young). Air pollutants may become trapped, increasing their concentration and the length of people’s exposure to them) and water pollution (in areas with high rainfall, pollutants on the street enter local bodies of water via storm drains).

In this activity, students will learn how rain gardens and other strategies that emulate natural processes help to reduce water pollution. Keep in mind what the different types and sources of pollution are and how a rain garden could help reduce these. Would this simulation prevent litter, small particulate, erosion or chemical pollution enter a natural body of water?

Vocabulary
bioswales - vegetated, mulched, or xeriscaped channels that provide treatment and retention as they move stormwater from one place to another. They are best along streets and parking lots.

rain gardens - Rain gardens are shallow, vegetated basins that collect and absorb runoff from rooftops, sidewalks, and streets. Rain gardens mimic natural hydrology by infiltrating and evapotranspiring runoff.

planter boxes - Planter boxes are urban rain gardens with vertical walls and open or closed bottoms that collect and absorb runoff from sidewalks, parking lots, and streets.

downspout disconnection -  the rerouting of rooftop drainage pipes to drain rainwater to rain barrels, cisterns, or permeable areas instead of the storm sewer. Downspout disconnection stores stormwater and/or allows stormwater to infiltrate into the soil.

Permeable Pavements: paved surfaces that infiltrate, treat, and/or store rainwater where it falls. Permeable pavements may be constructed from pervious concrete, porous asphalt, permeable interlocking pavers, and several other materials.

Materials

 * small rocks/pebbles
 * sand
 * soil
 * sod
 * mesh screen/support material
 * PVC pipe about 10 inches or water bottle
 * Mason Jar/Bottle to catch drainage water (must be at least as wide as water bottle/PVC pipe
 * Paper towels

PREP

 * 1) Set up PVC pipes/filter demonstration with one PVC pipe or water bottle each of a) only a mesh screen on the bottom, b) various combinations of small rocks, sand, soil & sod with a mesh screen on the bottom (particle size from largest to smallest)
 * 2) Place mason jar/bottle on the bottom of the PVC pipe/water bottle and a paper towel underneath the jar/bottle.

ACTIVITY

 * 1) Explain how rain gardens filter runoff (skip if Activity 1 is done)
 * 2) Ask students to predict which combination will filter the cleanest water (note that clearest does not necessarily mean cleanest)
 * 3) Have them put different materials provided in the water (sprinkles, glitter, different-sized beads?) modelling pollution.
 * 4) Pour the 'polluted' water into the chosen bottle/PVC pipe combination; observe results and explain.

How it fits to Standard

 * Answer questions by explaining observations of the natural world (K-1)
 * Develop a solution by using a simplified technological design process. Investigate the use of tools (2-3)

Follow Up
What combination filtered the most? What did the sprinkles, glitter, and beads each represent? Which material is best for filtering out sprinkles? Which is best for beads? Which material filters the fastest?