DAMAGE ASSESSMENT REPORT FOR WET CONCRETE IN A STEELHEAD CREEK
Concrete, mortar, plaster, grout or cement slurry is caustic and corrosive, with a pH of
about 12, and is similar to Drano. The main ingredient in concrete is Portland Cement,
which consists of cement clinker, calcium sulfate, calcium and magnesium oxides,
heavy metals, potassium and sodium sulfate compounds, chromium and nickel
compounds. Other contaminants include aluminum, barium, chromium, hexavalent
chromium (chromium 6), copper, iron, magnesium, manganese, tricalcium aluminate,
tetracalcium alumino ferrite, nickel, potassium, selenium, silica, sodium, vanadium and
zinc. According to the Material Safety Data Sheet, contact with wet concrete can cause
skin irritation and chemical burns or serious eye damage in humans.
The pH scale, (1 to 14) refers to the ratio of two molecules, the hydrogen ion (H+),
responsible for acidity, and the hydroxide ion, (OH-), which is responsible for alkalinity.
Battery acid has a pH of 1, sodium hydroxide has a pH of 14, and 7 is considered
neutral, that of pure water. The pH scale is a logarithmic measurement of the
concentration of hydrogen ions, meaning that one unit change in the scale equals a ten-
fold increase or decrease. Therefore a pH of 9 is ten times as alkaline as 8, and 10 is a
hundred times as alkaline as 8. Therefore each change in the scale represents a major
chemical change in alkalinity or acidity.
A pH of 6.5 to 8.5 is optimal for most aquatic organisms. A pH of 9.0 to 10.5 can be
harmful to salmonids with prolonged exposure. Exposure of 10.5 to 11.0 is lethal to
some species of fish. A pH of 11.0 and above is lethal to all species of fish. According
to the Environmental Protection Agency, a pH of 10.0 will kill salmonid fish within
Changes of pH in the water, will affect the toxicity of many dissolved compounds such
as ammonia, which becomes more toxic as pH increases. High levels of pH can cause
physical damage to skin, gills, and eyes of fish. Sub-lethal levels can cause stress,
increase mucus production and encourage epithelial hyperplasia, which is the
thickening of the skin or gill epithelia, which can have fatal consequences. Fish also
have to balance internal pH, and even small fluctuation of blood pH can be fatal, or can
result in acidosis or alkalosis of the blood. Fish culturists recommend that fish are not
added to new concrete holding tanks and that new concrete tanks are allowed to leach
out lime for several weeks before adding the fish.
High pH effects vegetation by inhibiting growth, damage to soil and plants and alteration
of the soil and plant chemical composition, even after the contamination is gone. The
bacterial population can also increase. Most soils have a pH of 4 to 8, and soils with a
pH above 8.5 become corrosive to vegetation and causes plants to wilt. Soil pH can
affect the availability of nutrients such as nitrogen and phosphorous.
Concrete wash water or suspended concrete particles in water, when discharged into a
fish bearing stream, will clog fish gills, reducing the amount of oxygen, which can lead to
death. The sediment can also smother aquatic habitat, cover redds (salmonid nests)
and impair feeding ability due to a decrease in visibility.
The water which leaches through the concrete bags to harden the concrete, is similar to
concrete wash water and is highly toxic. Even if filtered to remove the cloudiness or
solids, the toxic compounds are still there, in dissolved form, and the pH is still high
enough to kill fish. Concrete wash water or the water which leached from the bags, has
so much alkaline material, it overwhelms the buffering capacity of any stream. High pH
does not behave as expected when it is diluted. The levels stay elevated 1.5 times
higher than expected even after a five hundred-fold dilution. If any creek had high water
flows when the concrete bags were placed within the water line, and the concrete oozed
or leaked from the bags, a section of high pH contaminated water would move
downstream in a mass, until diluted, killing aquatics downstream. Readings of ph levels
should be taken continuously if this occurs.
Under emergency circumstances, repairs may occur without a Streambed Agreement
and CEQA requirements. But even under emergencies, best management practices,
protection for listed species, avoidance of pollution sources and habitat protection must
be included into the project.
10 Volumes Method to pH 8.5
One pound of lime will combine with or saturate 58.1 gallons of water, and thus form a
caustic solution having a pH of 12. To reduce the pH of the 58 gallons of caustic to a
tolerable pH (8.5) by dilution alone (ignoring diluent buffering) would require 290,441.9
gallons of water (5000:1 dilution).
Since pH is a logarithmic function, a solution diluted 10-fold will have a pH of one pH
If we start with 58.1 gallons of a saturated solution of lime (Solution A) (pH of 12)
To create a solution having a pH of 11 from that solution (Solution A) would
require 522.9 gallons of diluent 581 gallons of Solution B.
To create a solution having a pH of 10 from Solution B would require
5,229 gallons of diluent, 5810gallons of Solution C.
To create a solution having a pH of 9 from Solution C would require
52,290 gallons of diluent, 58,100gallons of Solution D.
To create a solution having a pH of 8.5 from Solution D would require only a 5-fold
dilution or 261,450gallons of diluent (5 x 52,290). The total diluent required would, thus,
be the sum of the individual dilutions (522.9 + 5229 + 52290 + 261,450) or 319,491
gallons of diluent.