Preventing Stormwater Pollution at Your Public Works Facility
Exercise for Module 1
Following the flow
The purpose of this exercise is for your staff to start noticing how
stormwater runoff flows through the facility, and to be aware of where
it eventually ends up.
Materials needed:
o Flip chart paper (sticky-backed is good, or have tape for
hanging)
o Markers
o Scrap paper
o Pens or pencils
o Recent air photo or other map of your facility and the
surrounding area1
o Site plan of your facility with elevations, if available2
o List of drinking water supplies, other DEM special resource
protection waters (DEM Water Quality Regulations) and impaired
waters (DEM 303d list). (This information may be obtained from
the MS4’s Storm Water Management Plan, the Planning
Department, or from DEM interactive map server).
Step 1) Break into groups of 2-3 people each, and provide each group
with flip chart paper and different colored markers. Make sure each
group has a blue marker and ask them to set it aside for the moment.
Step 2) Ask each group to draw a rough map of the facility property,
making the outline as large as possible, while still leaving enough
room on the paper to also make notes outside of the property lines.
Have them locate all permanent structures on their maps (e.g.
buildings, pavement, and gas pumps). They should feel free to use
any of the maps you have (the air photo and/or site plan maps).
Step 3) Ask each group to think back to the last time it rained enough
to cause the water to start to run. Where did the water concentrate
into little rivulets? What direction was it flowing? Where did it come
from? Where did it eventually end up? Where does the water leave
1 Visit http://maps.google.com/ and you can get an aerial image of your site
2
You can get a print of a basic elevation map from the web at http://www.dem.ri.gov/maps/index.htm.
Click on Environmental Resource maps, then click on the folder at “image layers” and make sure elevation
is checked. You’ll need to zoom in fairly close to your site on the state map before the images will appear.
You might also be able to ask your Planning Dept. for a map.
Module 1: Introduction to the Series and Why Stormwater Matters
Exercise
1
Preventing Stormwater Pollution at Your Public Works Facility
your property? Have the groups mark these “flow paths” on their
maps, using the blue markers to draw arrows. If the runoff goes into
a pipe system, have them draw a solid line to show where the pipe
goes.
If the groups are having trouble envisioning the flow paths, or don’t
know where the pipes go, take them outside to see, or refer them to
the elevation map of the facility.
Step 4) Have each group post their maps on the wall and look at the
results from the other groups. Make sure there is a general
agreement on where most of the runoff leaves the site. Then hand out
copies of the air photo (if you haven’t already), and work with the staff
to locate the facility and the discharge point. Have them draw a line
from the facility’s discharge point to represent where the water would
go from there.
When the water leaves the site does to pass to a local stream, pond,
etc. Where does it eventually go? Ask staff to name the nearby and
downstream waters that receive facility runoff, and describe their use
and condition. For example, are they used for fishing or swimming
areas; do they drain to coastal waters? Are they high quality or do
they have problems? Following discussion, distribute or display a list of
drinking water supplies, special resource protection waters and
impaired waters downstream from the facility. If space is available on
the map, have staff label these important water resources.
Step 5) Keep the maps on the wall for the next week or so, and invite
staff to add to them/make corrections as they watch actual runoff
patterns form.
Module 1: Introduction to the Series and Why Stormwater Matters
Exercise
2