Concrete holds feet, not water



Vladimir Malinsky, project manager with Snohomish County public works engineering services, pours water on the walking path near Marysville to demonstrate its porous construction. The environmentally friendly project saved the county more than $114,000.


The surface of the new $130,000 path near Marysville looks similar to a rice cake. It's made of porous concrete that allows water to filter through its surface.


By Kate Reardon 
Herald Writer 

MARYSVILLE -- Vladimir Malinsky pours a bottle of water on the walking path, and instead of pooling on top or running to the edge, the water trickles right through.

That's because the new 5-foot wide path on the south side of 100th Street NE between 48th Drive NE and 51st Avenue NE is made of pervious concrete.

The $130,000 walkway, which resembles a gray rice cake, is the first of its kind in Snohomish County.

The idea to use it for a walkway may open new doors to building environmentally-friendly paths and sidewalks in the county, said Malinsky, project manager with Snohomish County Public Works Engineering Services.

The innovative construction material provides a strong, hard surface but lets water percolate through to the ground.

The 900-foot long walkway was built over the summer to provide a much-needed pedestrian link for area residents to walk, jog, use wheelchairs and push baby strollers.

The area had been covered with bushes and trees, forcing Cascade Elementary School children and others to walk near or in the road.

Now, the path connects the business area to the west with a residential area and school to the east.

"It eliminates a headache and it saved money," county engineering supervisor Darrell Ash said.

The only drawback, Ash and Malinsky said, is pervious material is not always as strong as traditional concrete -- which explains why it hasn't been used for roads. It also creates a slightly rougher walking surface.

The project originally was designed to use traditional concrete and called for construction of off-site water detention ponds, curbs, gutters and underground catch basins. To do all that, the county would have had to buy additional land.

Malinsky said he saw an opportunity to use the pervious concrete, a material believed to have been used in one other sidewalk in the Seattle area. The material saved the county about $114,000 from the original project's budget.

Malinsky said he also liked the idea because the water drains through the path into the soil and will reach nearby streams gradually and naturally, reducing erosion, flooding and habitat damage, he said.

The material isn't new. In fact, Malinsky said he found information on the material in an engineering book published in 1979.

"It's a new application for an old material," he said, adding that it has been used for irrigation channels elsewhere.

If it's feasible, it could be used in other projects, Malinsky said.

"First we have to see how it works on the 100th Street site," county engineer Steve Thomsen said. "If it performs like we expect it to, though, we could end up using it for any number of future applications."

You can call Herald Writer Kate Reardon at 425-339-3455 or send e-mail to reardon@heraldnet.com.

 

 

KATE REARDON/The Herald

Vladimir Malinsky, project manager with Snohomish County public works engineering services, pours water on the walking path near Marysville to demonstrate its porous construction. The environmentally friendly project saved the county more than $114,000.

 


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Published: Monday, November 11, 2002
Source: The Herald