Why concrete washout is harmful to the environment

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Most contractors know that concrete slurry or washout can cause a fish kill, if it reaches a lake or stream.  That's because the fluids are highly alkaline--as corrosive as draino.  And aquatic organisms are extremely sensitive to changes in Ph (alkalilnity).  

For that reason, it's illegal in Madison to discharge washout to the gutter.  Violations are enforced by Public Health and referred routinely for prosecution.  Contractor Report documents washout spills with photos and reports them immediately to Public Health.

However, dumping concrete waste or slurry to the soil is legal.  But that doesn't make it a good practice or good public relations.  There's increasing evidence, reported below, that concrete waste in the soil has the potential to harm the environment and degrade our drinking water.

Life far underground

In the last 20 years, our knowledge of bacteria has undergone a revolution.  We now know that bacteria can live inside solid rock.  Bacteria live and reproduce high in the clouds--where they help form rain as water condenses upon their bodies.

Edgewater construction causes muddy plume in Lake Mendota

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In the evening of May 27, 2014, shortly after the heaviest downpour ended, a boater* observed a muddy plume extending 100 feet out from the Edgewater Hotel construction site into Lake Mendota.

The observer noticed an eroded rill on the east side of the construction site, but did not actually observe the runoff leaving the site.  However, the location of the muddy plume strongly suggests that Findorff Construction, the main contractor at the site, was responsible.

"The National Weather Service says Madison set a record for daily rainfall with 1.36 inches." Source

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*  The observer wishes to remain anonymous.

Previous sediment spill by Findorff at the Edgewater reconstruction.