Storm Water by the Numbers
Sampling Data
Most samples for biochemical oxygen demand or
BOD
are reported at <12.00 mg/L, below the arbitrary
EPA/DNR limit of 30.0 mg/L. When discarding the
data from late delivery and warm samples the aver-
age for the industry was 9.5 mg/L in the 2004 data set
and 10.2 mg/L in 2011-2014.
This mainly indicates
that icing the sample and prompt delivery are impor-
tant factors in quality sampling.
The low BOD levels
can be attributed to keeping hoods closed and keep-
ing parts from being exposed to rainfall.
The biochemical oxygen demand or
BOD
test is used
to determine if organic pollutants exist in the sample
water. Organic means that it once came from a life
source and is commonly accepted as meaning it con-
tains carbon. Many automotive fluids such as fuel,
crank-case oil and cleaning solvents have emulsified
or dissolved organic compounds that can increase the
BOD results.
Average Chemical oxygen demand or
COD
test re-
ported at 139.5 mg/L and 153.2 mg/L for the two data
sets. Even when data from late/warm deliveries of
sample to lab were discarded the average fell danger-
ously close to arbitrary EPA/DNR limit of 120.0 mg/L,
although only 25% of the samples actually exceeded
the threshold. Icing and prompt delivery is an impor-
tant factor in this analysis as well.
The COD levels
can be attributed to management of automotive fluids.
High chemical oxygen demand or
COD
are waste
containing chemicals, such as arsenic, cadmium,
chromium, copper, lead, mercury, molybdenum,
nickel, selenium, and zinc come from metals leached
out of the engine block or battery into the antifreeze,
lubricants, and fuels.
The measure of erosion at the salvage yard is the To-
tal Suspended Solids or
TSS
these average values
fell above the arbitrary EPA/DNR limit of 100 mg/L in
both studies. The most important aspect here is that
in both data sets over 2/3 of the sites were unable to
attain a measure of erosion within the parameter
threshold. The addition of gravel to the drive lanes
may improve the situation.
Total Suspended Solids or
TSS
can indicate the ero-
sion from the yard.
High TSS enables pollutants to
attach to solids and travel off the property easily. It
can also indicate a fast flow rate or a direct path of
storm water discharge to the outfall. Fast running wa-
ter can carry more suspended solids. Slow running
water has more opportunity for solids to settle back
onto the property. Pollutants that show up in other test
results can also be suspended solids.
Total Kjeldahl Nitrogen or
TKN
values were below the
arbitrary EPA/DNR limit of 19.0 mg/L. In over 100
samples only one sample exceeded the threshold.
TKN measures the nitrogen in pollutants which comes
from fertilizer and sanitary wastes including animal
manure.
The low nitrogen levels can be attributed to
good maintenance and diligent management of haz-
ardous wastes.
Phosphorous (
P
) values were below the arbitrary
EPA/DNR limit of 2.0 mg/L. Fewer than 10% of the
samples were above the threshold.
Phosphorous (
P
)
and phosphates are common components of water
washing soaps. Phosphorous is also fertilizer.
Each test parameter has its own unique characteris-
tics that identify pollutants in storm water runoff. But it
is the complete set of parameters that will give the
yard a fair picture of the quality of the water being dis-
charged from the salvage yard to the local lakes and
streams.
Best management practices can success-
fully be utilized to keep pollutant loading within regula-
tory guidelines but ongoing effort will be required to
maintain acceptable erosion levels.
Recyclers News Press
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