Concrete Washwater
Harmful Ingredients
Concrete or cementitious (mortar, grout, plaster, stucco, cement, slurry)
washout wastewater is caustic and considered to be corrosive with a pH over 12,
essentially the same as Liquid Drano®, Ammonia or other household cleaning
detergents. The primary ingredient in ready mixed concrete is Portland Cement,
which consists of Portland Cement Clinker, Calcium Sulfate, Calcium and
Magnesium Oxide, heavy metals and potassium and sodium sulfate compounds,
chromium compounds and nickel compounds. Some of the contaminants contained
within concrete washwater include; Aluminum, Barium, Chromium, Hexavalent
Chromium (Chromium 6), Copper, Iron, Magnesium, Manganese, Nickel, Potassium,
Selenium, Sodium, Vanadium, and Zinc. The washwater may also contain trace
elements of petroleum products, admixtures and other materials from processing
or treating the material. The graph to the left outlines the contaminants and
their respective levels.
Contact with
wet (unhardened) concrete, mortar, cement or other cementitious materials can
cause skin irritation and severe chemical burns or serious eye damage.
What is pH?
pH is a measure of how acidic or alkaline a
substance is. The pH scale goes from 0 to 14, where 7 is neutral. A low pH
value means the sample is acidic, while a high pH value means that the sample
is basic or alkaline. A change in one pH unit means a tenfold change in
concentration, similar to the Richter scale and measuring earthquakes.
Effects of High pH on Aquatic Life
The effects of high pH on fish may include:
DEATH; damage to outer surfaces like gills, eyes, and skin; and an inability to
dispose of metabolic wastes. High pH may also increase the toxicity of other
substances. For example, the toxicity of ammonia is ten times more severe at a
pH of 8 than it is at pH 7. The safe range for aquatic life is between 6.5 –
9.0 pH units. The average pH of concrete washout water is near 12 pH units.
Effects of High pH on Vegetation
The effects of high pH on vegetation may
include: inhibited growth, damage to soil and plants and substantial alteration
of the soil and plant chemical composition even after the pollution source is
gone. High pH may also increase the toxicity of other substances causing
further problems. The safe range for plant life is between 6.5 – 7.0 pH units.
The average pH of concrete washout water is near 12 pH units.
High Suspended and Dissolved Solids Count
Concrete wash water is basically slurry of fine
Portland Cement particles in water, also called suspended solids when in water.
When illegally discharged into a fish-bearing waterway, it will clog fish
gills; reducing the amount of oxygen they receive which can ultimately lead to
death. It can also smother aquatic habitat, impair their feeding ability and
permanently damage the fragile ecosystem we enjoy. Turbidity, which refers to
water clarity, is related to suspended solids. In clear water, the turbidity is
0 NTU and fish are able to capture their prey, however as the turbidity
increases to 60 NTU, certain fish are only able to capture 5% of their prey. The
average turbidity of concrete washout water coming directly from the source is
27,000 NTU. The average stream or river in the United States has a total
suspended solid count of no more than 75 ppm. The average total of suspended
solids in concrete washout water coming directly from the source is 79,000 ppm.
Impaired Waterways Impact Us All
40% of the waterways in the United States are
still impared; unable to swim, fish, play or otherwise use the waterway and 70%
of those because of non-point source pollution (ie., concrete washout water). As
construction in the United States and worldwide continues to boom, we are faced
with a pollution problem of epidemic proportions. The building and concrete
industries need to continue to combat this problem quickly, effectively and
need to be armed with the most innovative and state of the art equipment and
procedures available; Concrete Washout Systems portable and patented roll-off bin.
What is CWS Doing About It?
CWS is the ultimate risk management and
compliance system for concrete washout containment. Not only do we have a
product that controls, captures and contains all of the concrete and washwater
material, we employ a system and method in which we divert and recycle the
concrete material and recycle all of the caustic concrete washwater that was
generated on a jobsite. CWS has also developed a patent pending treatment and
recycling system that reduces the contaminant levels in concrete washwater so
it may be used for other applications and/or recycled.