In 2004 the storm water sampling baseline study was
conducted at the Iowa Waste Reduction Center by Sue
Schauls and funded by an EPA grant. Data was col-
lected or compiled from existing sources to provide a
better understanding of what the numbers mean to an
automotive salvage yard in Iowa. At that time, and still
true under the current permit, salvage facilities are re-
quired to collect annual storm water runoff and send it
to a laboratory for analysis of specific parameters.
Many of the surrounding states in the Midwest are now
required to conduct quarterly sampling. Currently the
baseline data study is being compared to data com-
piled from storm water collected during compliance
monitoring from 2011 through 2014.
Storm water samples are required to be analyzed for
the seven parameters set forth by the US EPA as re-
quirements of the National Pollutant Discharge Elimi-
nation System or NPDES program administered in
Iowa by the DNR. Although no limits have been placed
on the results of the samples, the data can be useful in
determining the level of pollution being discharged
from the salvage yard through storm water runoff.
Two sets of samples, the grab sample and the com-
posite sample, are sent to the laboratory for analysis
per the NPDES requirements for each physical loca-
tion of an Iowa salvage yard. The grab sample is also
known as the first flush because it is a sample taken
during the first hour of the rain event. The composite
sample is made of several small samples taken over a
short period of time. Each set of samples is tested for
five parameters plus the grab sample is also tested for
oil and grease as well as pH.
In surrounding states additional parameters or different
parameters are required for testing that measure met-
als in the runoff. Most of the states that have gone to
quarterly sampling also have set benchmark limits for
the contaminant loading in the storm water. Conse-
quences such as increased testing or timelines to
make changes are levied when sample parameter lim-
its are exceeded unlike in Iowa that simply requires
testing and implementation of Best Management Prac-
tices or BMPs. In the table the parameters and the
study results are presented
Parameter
Target
2004 Study
2014 Study
Oil & Grease
15.0 mg/L
<5.0 mg/L
<5.0 mg/L
pH
6.5 to 8.5
7.0+/- pH
7.0+/- pH
BOD
30.0 mg/L
9.5 mg/L
10.2 mg/L
COD
120.0 mg/L
139.5 mg/L
153.2 mg/L
TSS
100 mg/L
354.2 mg/L
890 mg/L
TKN
19.0 mg/L
3.75 mg/L
4.5 mg/L
P
2.0 mg/L
1.1 mg/L
0.7 mg/L
Most grab sample
oil and grease
values were re-
ported at <5.00 milligrams per Liter (mg/L) in both the
2004 study and the compilation of data gathered from
2011 through 2014. Although the averages were much
higher, 31.7 mg/L and 6.72 mg/L respectively, the
mode (most frequently occurring) value is perhaps
more significant as the outlier in the data tend to spike
the averages. The mode value is below the arbitrary
EPA/DNR limit of 15.0 mg/L. Low
Oil & Grease value is
likely attributed to the clean yards and the processing
of vehicles before placing in the storage yard.
Oil and grease
contamination is obvious by the oil
sheen on standing and slow flowing water as is its ori-
gin. Oil and grease pollution is easily controlled at sal-
vage yards through implementation of Best Manage-
ment Practices as identified in the yard’s Storm Water
Pollution Prevention Plan.
The pH of the storm water runoff from salvage yards is
basically neutral from data collected at the lab and not
the more accurate field testing. The values are within
the healthy pH range of 6.5 to 8.5 for life sustaining
water. The 2004 study found no samples outside of the
neutral range and the 2014 data indicated 17% were
above or below pH level for neutral, although the sheer
number of samples in the second data set could con-
tribute to the wider range.
The neutral pH level indi-
cates that no problem areas exist and can be attrib-
uted to the covered storage of batteries and other
waste products.
The
pH
of the storm water runoff is a good way to
identify a problem exists. Typical rainfall has a pH of 5
to 6 which is slightly acidic. A pH value that indicates a
high acid or alkaline runoff is likely caused by a spe-
cific problem area such as uncovered battery storage
or wash station discharge.
Recyclers News Press
Page 16
Storm Water by the Numbers
Sampling Data
