Category Archives: Turbidity

Permeable Paving Demonstrated at Lake Atalanta

by: Angela Danovi, Program Director of Beaver LakeSmart

Water quality protection, reduced runoff, and aesthetically pleasing public parking are just some of the benefits Ozarks Water Watch has helped to contribute in the current renovation at Lake Atalanta in Rogers.  Over the past several weeks, we have shared photos and information about the permeable paver project.  Today, we are going to share photos and information about how the pavers were installed and the benefits the pavers will provide to the community and to water quality in the Lake Atalanta and Beaver Lake Watershed.

What are Permeable Pavers?

Permeable is a term used to describe paving methods for roads, parking lots, and walkways. A permeable paving system allows water and air to move around the paving material. The permeable pavers that have been placed near the entrance to Lake Atalanta are an interlocking paver.  They look similar to a brick.  However, they have small notches on the side that allows them to interlock with one another while leaving space for rainwater to infiltrate into a layered media that is placed beneath the pavers.  Permeable pavers are different from pervious pavers because water cannot infiltrate through the paver but is instead directed to the edge of the paver where it infiltrates into the ground.  Learn more about the type of permeable pavers installed at Lake Atalanta here.

Bethany Alender from Beaver Watershed Alliance holds a pervious paver during a demonstration installation at Lake Atalanta

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Permeable paver with interlocking notches allows for the pavers to lock together while leaving space for water to pass between pavers and infiltrate into underlying media

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Pallets of Unilock interlocking permeable pavers at the construction site prior to installation.

How are permeable pavers installed?

A permeable paving system generally has three layers of clean gravel.  Each subsequent layer of gravel is smaller than the layer the beneath it.  The interlocking pavers sit on top of the layer of the smallest size gravel.  In some systems small rock is placed between the pavers to maintain space and allow water to infiltrate between the pavers.  For the system at Lake Atalanta, the notches on each paver lock the network of pavers together while leaving space for water to infiltrate between them.

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A base layer of clean and washed gravel is laid as part of the permeable paver system at Lake Atalanta

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The second layer of clean and washed gravel is laid as part of the permeable paver system at Lake Atalanta

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The second layer of the permeable paver system is compacted.

 

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Top layer of clean and washed chipped rock is spread over the permeable paver site.

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The top layer of chipped rock in the permeable paver system is spread and evenly layered.

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The pavers are placed by hand, interlocking each of the notches together and are gently tapped into place.

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Design plan for permeable pavers. The pavers are laid out in a herringbone pattern.

 

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The pavers are placed by hand, interlocking each of the notches together and are gently tapped into place.

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The four layers of the permeable paver system at Lake Atalanta

 

See the finished permeable pavers at Lake Atalanta:

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The permeable paver parking area at Lake Atalanta

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Installed permeable paver interlocked together with space for water infiltration

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Edge of the permeable paver system. The system will be enclosed with curbs on the outer edge and concrete on the inner edge.

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The completed permeable paver project at the entrance to Lake Atalanta

 

Benefits of Permeable Pavers to the Community:

  1. Permeable or pervious pavers allow water to infiltrate back into the ground.  This allows for rainwater to recharge local groundwater supplies, rather than quickly running into nearby creeks or streams.
  2. Permeable pavers reduce flashy runoff during rain storms.  Flash flooding is a result of rain falling on too much impervious surface in a concentrated area during a storm.  With permeable pavers, water can infiltrate into the ground, reducing runoff during rainstorms, reducing high streamflows during storms, and allowing water to slowly percolate, providing more water for streams throughout the year, rather than just during storms.
  3. When reflective, light-colored pavers are used, permeable pavers can be effective in reducing the urban heat island effect. Conventional asphalt absorbs most of the sunlight that strikes it because of its dark color.  That light is converted to heat and radiated back out, contributing to relatively higher temperatures in paved or urban areas.  This is known as a heat island.  By using light colored pavers, more light is reflected and less and is converted into heat, reducing the urban heat island effect.
  4. Due to their design, permeable pavers can provide a safer driving surface in hazardous winter driving conditions.  Unlike conventional asphalt and concrete, which provides a foundation for sheets of ice to develop in winter weather conditions, permeable pavers allow for ice to only form in small sections, providing less continuous surface area for sheet of ice to form, and allowing sunlight to penetrate the ice and melt it quicker.
  5. Permeable pavers protect local water resources.  By reducing runoff and increasing infiltration, permeable pavers also help to reduce pollution.  When a raindrop hits a surface, that raindrop will carry with it sediment and any pollution laying on the earth’s surface, where the raindrop strikes.  By allowing the raindrop to soak into the ground, rather than running to the stream, sediment and pollutants are captured in the ground and cleaner water will slowly release to the stream or percolate into the groundwater.
  6. Permeable pavers reduce thermal pollution in streams.  Thermal pollution is pollution resulting from abnormally hot water entering a waterway.  Hot water discharges to streams can come from many sources including industry.  One of the most common sources of thermal pollution is from asphalt parking lots.  By installing permeable pavers, water that would strike a hot parking lot and runoff, is allowed to soak into the ground, percolate through the soil, and cool to an appropriate temperature before entering a waterway.  By reducing thermal pollution, the habitat of aquatic species is protected.

Benefits of Permeable Pavers to the landowner:

  1. With increased infiltration and runoff reduction, permeable pavers can help reduce costs associated with erosion.  Permeable pavers may even be effective in reducing irrigation to nearby grass or plants.
  2. Permeable pavers are easily replaced.  if one becomes chipped or broken, the individual paver can be lifted out of place and replaced with a new one, extending the overall life and function of pervious paving project for relatively little cost.
  3. Permeable pavers provide an aesthetically pleasing design to any outdoor space.  Due to the versatility in design, they can be placed in any size or shaped area and provide a more pleasing design than concrete would allow.

Thank you to our project partners

The Environmental Protection Agency Region 6, through the Arkansas Natural Resources Commission has provided partial funding for this project under Section 319 of the Clean Water Act.

 

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Why does that water look so dirty?

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War Eagle Mill sits in the middle of War Eagle Creek in Northwest Arkansas, December, 2015. Photos: Stuart Covey. Photo obtained from Garrett Lewis on Facebook

Just a few weeks ago Northwest Arkansas became flooded after 10 inches of rain fell across the area.  People flocked up to Beaver Dam for the rare sight of water spilling through the gates while others took the opportunity to capture breathtaking photos such as the one above. One unifying theme in all of the flood waters was mud!

These water bodies, War Eagle, West Fork, the White River, and others, don’t usually appear this muddy to us.  Perhaps since this was an extremely high flood event, we don’t think about mud in water being a problem.  But the mud, or sediment, in water is a problem.  In fact, sediment is considered the number 1 water pollutant in water!

What’s the problem?  It’s just mud!

Sediment knocks two punches into lowering water quality because it is a pollutant and it is also a carrier of pollutants.  Sediment as a pollutant can cause harm to aquatic life including fish and macroinvertebrates.  It can get caught in the gills of these animals, smother their habitat and breeding areas, and reduce the availability of food.  Water bodies with high levels of sediment may have higher temperatures due to increased absorption of sunlight.  It also costs more to take sediment out of surface water that is treated for drinking water.  For example, on Monday, December 28, 2015, near the peak of the flood, the Beaver Water District extracted 136 tons of mud or sediment from the water it treated. That’s about six times more than the usual 22 tons!

As a pollutant carrier, sediment can deliver increased nutrients, bacteria, and chemicals to waterways.  Those pollutants can adsorb or attach to sediment particles.  Once those sediment particles are detached from the surface of the earth, anything attached to them goes along for the ride, often ending up in the nearest waterway.  For example nutrients found in fertilizers, wastes and manures, and some cleaners, will get into the water after being attached to a soil particle!

While natural erosion produces nearly 30 percent of the total sediment load in the United States, accelerated erosion from human use of land accounts for the remaining 70 percent of sediment that goes to our surface waters!  Sediment pollution causes up to $16 billion in environmental damage annually.

Our friends at the University of Arkansas Cooperative Extension Service provided this short video to demonstrate some ways that sediment and anything attached to sediment can get into our surface waters.

https://www.youtube.com/watch?v=JSpO7nK1Bak

 

Turbidity

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Photo Credit: University of Arizona

Turbidity is a measure of the amount of suspended sediment and visible particles in a sample of water, or essentially, turbidity measures the cloudiness of the water. So clear water has low turbidity (beaker on the left) and water with high turbidity is more opaque (beaker on the right).  We want our waters to stay clear in order to keep ourselves healthy, our aquatic life healthy, and our water healthy!

 

What can you do to keep our waters clear and mud free?

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http://www.fws.gov/r5crc/salmon/workbook/buffer.htm

Build a Buffer – Avoid mowing within 10 to 25 feet from the edge of a stream or creek. This will create a safe buffer zone that will help minimize erosion and naturally filter stormwater runoff that may contain sediment.

 

 

Sweep, Don’t Spray!  Sweep sidewalks and driveways instead of hosing them off. Washing these areas results in sediment and other pollutants running off into streams, rivers and lakes.

Use Best Management Practices:  The most concentrated sediment releases come from construction activities, including relatively minor home-building projects such as room additions and swimming pools.  If you are engaged in a construction project, be sure to identify and implement appropriate best management practices to reduce runoff and increase water infiltration.  The Arkansas Forestry Commission has some great recommendations for BMPs to use when doing even small construction projects on your own property at http://forestry.arkansas.gov/Services/ManageYourForests/Documents/bmpbookrevise.pdf

No dirt in water or the streets!  Notify local officials when you see sediment entering streets or streams near a commercial construction site.  Sediment should never be flowing off of a construction site, nor should it be tracked into the street.

Cover up the bare spots!  Bare soil is endangered soil!  Protect your soil and property by covering up bare spots.  Use weed-free mulch when reseeding bare spots on your lawn, and use a straw erosion control blanket if restarting or tilling a lawn  In gardens, put compost or weed-free mulch on your garden to help keep soil from washing away.

Wash the car on the grass!  Wash your car at a commercial car wash or on a surface that absorbs water, such as grass or gravel.  Washing the car on a hard surface sends dirt, chemicals, and cleaners straight to the nearest waterway!

 

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You can help keep our waters clear and healthy!

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