Page 135 - California Stormwater Workshop Handouts

Industrial General Permit Fact Sheet

permit that requires Dischargers to sample four storm events within each
reporting year.

b. Effluent Water Quality Sampling and Analysis Parameters

Dischargers are required to sample and analyze their effluent for certain
parameters. “Parameter” is a term used in laboratory analysis circles to
represent a distinct, reportable measure of a particular type. For example,
ammonia, hexavalent chromium, total nitrogen and chemical oxygen demand are
all parameters that a laboratory can analyze storm water effluent for and report a
quantity back. A parameter is also an indicator of pollution. In this General
Permit, pH, total suspended solids and chemical oxygen demand are examples
of indicator parameters. They are not direct measures of a water quality problem
or condition of pollution but can be used to indicate a problem or condition of
pollution. Indicator parameters can also be used to indicate practices and/or the
presence of materials at a facility to bring forth information for compliance
evaluation processes, like annual report review and inspection. For example,
chemical oxygen demand concentrations can indicate the presence of dissolved
organic compounds, like residual food from collected recycling materials.

Minimum parameter-specific monitoring is required for Dischargers, regardless of
whether additional facility-specific parameters are selected. This General Permit
requires some parameters to be analyzed and reported for the duration of permit
coverage to develop comparable sampling data over time and over many storm
events and to demonstrate compliance. The Regional Water Boards may use
such data to evaluate individual facility compliance and assess the differences
between various industries. Accordingly, the parameters selected correspond to
a broad range of industrial facilities, are inexpensive to sample and analyze, and
have sampling and analysis methods which are easy to understand and
implement. Some analytical methods for field measurements of some
parameters, such as pH, may be performed using relatively inexpensive field
instruments and provides an immediate alert to possible pollutant sources.

The following three selected minimum parameters are considered indicator
parameters, regardless of facility type. These parameters typically provide
indication and/or the correlation of whether other pollutants are present in storm
water discharge. These parameters were selected for the following reasons:

i. pH is a numeric measurement of the hydrogen-ion concentration. Many
industrial facilities handle materials that can affect pH. A sample is
considered to have a neutral pH if it has a value of 7. At values less than 7,
water is considered acidic; above 7 it is considered alkaline or basic. Pure
rain water in California typically has a pH value of approximately 7.

ii. Total Suspended Solids (TSS) is an indicator of the un-dissolved solids that
are present in storm water discharge. Sources of TSS include sediment from
erosion, and dirt from impervious (i.e., paved) areas. Many pollutants adhere
to sediment particles; therefore, reducing sediment will reduce the amount of
these pollutants in storm water discharge.

Order 2014-0057-DWQ 51