Stormwater 101

With water an abundant resource in Pennsylvania-the Pittsburgh area gets about 37 inches of rainfall a year-our lawns usually stay green, unlike drier places in the United States, and we are fortunate to have few drought advisories. Sometimes, though, all of that stormwater can be a challenge to manage properly.

Where Does McCandless' Stormwater Go?

McCandless has separate storm and sanitary sewers. When we flush our toilets or take a shower, that wastewater flows to a wastewater treatment plant. When it rains, stormwater from roads, parking lots, and roofs is collected in pipes that are separate from the wastewater pipes and is directed to stormwater basins, drainage swales, and finally to streams. Many of the older portions of Pittsburgh and boroughs such as Etna and West View have a combined sewer system, where both rainwater and sewage are collected in the same pipes and are treated at Allegheny County Sanitary Authority (ALCOSAN).

Streams in McCandless

Girtys RunThere are at least seven major streams that flow through McCandless: Girtys Run, Lowries Run, Pine Creek, North Fork Pine Creek, Rinaman Run, West Little Pine Creek, and Wexford Run. These streams are fed by groundwater, by overland flow from rainfall, and also by the stormwater collected from homes and businesses. This stormwater runoff can pick up pollutants along the way and wash them into streams. Examples of these pollutants are deicing chemicals, oil and grease from cars, rubber from tires, lawn chemicals, and trash. (Girtys Run pictured)

Stormwater runoff can also cause flooding and erosion of the stream banks. With a sudden, heavy rainfall, the stream levels rise quickly and the fast flow erodes exposed stream banks. This generates high sediment levels in the streams, which is unhealthy for the fish and for the insects that live in the stream that fish feed on. The sediment makes its way further downstream and is deposited in places such as North Park Lake or in other portions of the stream where the water slows down.

The more impervious that surfaces are constructed, such as buildings, parking lots, and roads, the higher and more forceful the stormwater flows become. The collective increase in stormwater flows from upstream areas impacts our neighbors downstream (for example, Millvale, Etna, and Emsworth) with the sediment deposited in their stream channels and with increased flooding.

Managing the Runoff - What Homeowners Can Do

The major streams are important, but the very small and the intermittent streams that many of us have nearby are important too. Because there are thousands of linear feet of little streams for each linear foot of major stream (like twigs versus a tree trunk), the small headwater streams are especially important in managing stream water quality and stormwater volumes.

Rain Barrel and Watering CanFollowing are several valuable steps you can take to improve the water quality in our local streams:

  • If you use lawn chemicals, apply them carefully and sparingly, and never just before rain is predicted. Remember, more is not always better.
  • Avoid impacts from car wash runoff (grime, detergents, etc.) by taking your car to a car wash facility that has a water recycling system, so that it doesn't generate runoff, rather than washing it in the driveway or in the street.
  • Sweep your driveways and sidewalks instead of using a hose.
  • Check your car for leaks.
  • Pick up after your pet.
  • If you have a stream along or through your property, don't dump yard waste near the edge or store any materials that can be washed away within 10 to 20 feet of the stream or edge.
  • Prevent erosion by leaving a 10 to 15 foot buffer on each stream bank where you don't mow. Roots from taller plants, like woody shrubs, are critical for holding the stream bank earth in place. Roots from grass are very shallow and don't help much. The dense plant growth also filters out pollutants before they reach the stream.
  • Promote stream community health by encouraging woody shrubs and trees to grow along the stream bank. The taller plants provide wildlife habitat, contribute a critical food source to stream insects, and provide shade, which keeps the water cooler and, in turn, promotes higher oxygen levels for the fish and insects.

Following are steps you can take to help reduce stormwater quantity. Infiltration of the rain into the ground and then into the local water table helps to keep streams at a steady level. To help the rainfall infiltrate and be absorbed where it falls, consider the following actions:

  • Disconnect your downspouts from the storm sewers and install rain barrels to capture rainfall to use to water your garden.
  • Disconnect your downspouts from the storm sewers and install a rain garden to capture and absorb the water instead of having it go down a pipe. Visit the (Rain Garden Alliance) for more information.
  • Again, do not mow the stream buffer area, as the taller plants absorb a lot of water before it reaches the stream, and leaf litter acts like a sponge.
  • Plant and maintain trees. Trees absorb rainfall by their roots and intercept rainfall with leaves. In urban and suburban settings, a single deciduous tree can intercept between 500 and 760 gallons per year, while a mature evergreen can intercept over 4,000 gallons per year.
  • If you have a large area of grass on your property, consider naturalizing it to an attractive wooded area with trees, mulch, and native plants. Placed properly, the shade of your trees will cool your home and improve the air quality by filtering pollutants, and you'll create fewer pollutants by mowing less.

Please note that if you disconnect any downspouts from the storm sewers, be sure that the water flows away from your foundation and does not become a problem for any downhill neighbors.

Source: North Area Environmental Council