Surface Water Topics

What About Snow and Ice!
We typically see snow only a few days each winter, so snow close to our homes and workplaces can catch us by surprise.  Freezing and icy temperatures are more common, but can also surprise us.  Even though we do not have the more constant snowy or icy conditions of other parts of the U.S., it is important to be prepared!

Using de-icing salts on sidewalks and pavements
Salts and similar de-icing chemicals can be used to excess.  In addition to being wastefully expensive when over-used, these salts and chemicals tend to remain in snow and melt water alike, and can be hazardous to children, pets, and fish or other wildlife exposed to the snow or runoff (particularly either drinking the water or swallowing the snow).

1.  Do not use de-icing salts or chemicals on the paved surfaces while the snow is still falling.  Keep clearing paved surfaces with shovels until the snow fall has stopped.

2.  Only use de-icing salts and chemicals to the minimum needed to melt the surface and make your priority walkways and driveways safe to use.  Once those surfaces are melted, remove excess salts or other de-icers and dispose properly as you would similar materials.

3.  Follow the guidance and advice below for encouraging water from melting snow to run off and drain as promptly as possible.  This will both reduce the continuing risks of these areas refreezing back into ice and reduce the amount of pollutants in the stormwater system.

4.  Snow and slush are good insulators of icy conditions under them, and can protect ice below the snow/slush layer from being melted by de-icing salts and chemicals.  Make sure areas are as well-shoveled as possible before using de-icing salts or chemicals

Shoveling snow guidance
1.  Purchase a snow shovel early, if you don't already own one.  They sell out fast once snow starts falling!

2.  Pick a snow shovel you can use comfortably.  Bigger is not necessarily better, particularly when the snow to be shoveled is wet.

3.  Locate all your property drains, as well as the nearby street drains.  Once covered by snow and ice (especially if further covered by a snow plow), drains are very difficult to find.  It is important to keep drains uncovered to drain off water from melting snow.  Always avoid piling snow over drains!

4.  Identify areas in advance to pile snow from your shoveling and/or plowing.  Pick areas where you do not normally see ponding during rainy weather.  Avoid areas that will not drain runoff surface water from melting snow.  Avoid picking areas that will drain runoff surface water from melting snow onto your paved areas.  Avoid piling snow over drains!

5.  Street plows typically cannot plow curbs and gutters in streets well.  Plowed snow from the street (as well as from sidewalks, driveways, and other paved areas) can cover street drains.  If you see a covered street drain, shovel the snow off to reveal the drain grate.  Remember:  shovel from the sidewalk or behind the curb; do not work in the street!

6.  Try to clear a couple feet on all sides of drains and, when possible, shovel corridors to drains from various areas.  Both of these will help runoff from melting snow to drain away as promptly as possible.

7.  Clear your downspouts to make sure water melting from your roof flows away from your building.  Avoid allowing snow sliding off your roof to accumulate right at the base of your building walls, as melting water from this snow may make it into a basement or crawlspace.

8.  Snow and ice almost always melt fastest when the paved surfaces are all or partially/thinly exposed to any sun or warmer air temperatures during the day.  Once melted, runoff water should be encouraged to drain off paved areas as quickly as possible before it can refreeze.

Runoff is surface water that flows from one area to another.  During rain storms, that runoff starts from where the rain lands and flows downhill however it can.

When it starts raining, even a small city of Mill Creek's size can produce and accumulate a lot of runoff water quickly.  The city is about 4.7 square miles in area (nearly 3,000 acres or nearly 130 million square feet!).  Even the grassy and other vegetated areas in Mill Creek do not absorb all the rain right where it lands. 

All that runoff that needs to be controlled and helped to flow down to North Creek.  Our combination of public and private stormwater pipes and facilities help with that, along with our natural streams like Penny Creek.

Even with nearly 3,600 street storm drains in the city to collect runoff, and nearly that same number of additional drains located in parking lots similar areas, it is common for water to pond up and not drain away quickly.  Hard surfaces like streets and driveways are particularly prone to this ponding.

What can I do?

Keep drains and gutters clear
Leaves and other debris from trees and plants tend to accumulate, sometimes very quickly, at drain grates and similar structures.  Even a small accumulation can either partially block water flow or deflect it in an unwelcome fashion.

Use rakes and remove any debris that accumulates.

Keep leaves out of the street
Do not blow leaves from yards into the street, even if you think the City street sweeper will pick up the debris.  Sweepers are not designed for that work, and City staff cannot sweep all city streets fast or frequent enough to remove excess leaves and other debris in the street.  Instead, dispose of all leaves from your yard and property as yard waste.

Prepare for winter storms
Begin planning for storm preparedness now, while you have plenty of time!

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Angela Bolton
Surface Water Program Coordinator
Phone: 425-921-5752
Email: [email protected]
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