Page 136 - California Stormwater Workshop Handouts

Industrial General Permit Fact Sheet

iii. Oil and Grease (O&G) is a measure of the amount of O&G present in storm
water discharge. At very low concentrations, O&G can cause sheen on the
surface of water. O&G can adversely affect aquatic life, create unsightly
floating material, and make water undrinkable. Sources of O&G include, but
are not limited to, maintenance shops, vehicles, machines and roadways.

The previous permit allowed Dischargers to analyze samples for either O&G or
Total Organic Carbon (TOC). This General Permit requires all Dischargers
analyze samples for O&G since almost all Dischargers with outdoor activities
operate equipment and vehicles can potentially generate insoluble oils and
greases. Dischargers with water soluble-based organic oils may be required to
also test for TOC. The TOC and O&G tests are not synonymous, duplicative or
interchangeable.

This General Permit removes the requirement to analyze for specific
conductance as part of the minimum analytic parameters. Specific conductance
is not required by U.S. EPA for any industry type. Additionally, stakeholder
comments indicate that there are many non-industrial sources that may cause
high specific conductance and interfere with the efficacy of the test. For
example, salty air deposition that occurs at facilities in coastal areas may raise
the specific conductance in water over 500 micro-ohms per centimeter
(µhos/cm). Dischargers are not prevented from performing a specific
conductance test as a screening tool if it is useful to detect a particular pollutant
of concern as required (e.g. salinity).

This General Permit requires Dischargers subject to Subchapter N ELGs for pH
to analyze for pH using approved test methods in accordance with 40 Code of
Federal Regulations part 136. These federal regulations specify that analysis of
pH must take place within 15 minutes of sample collection. All other Dischargers
may screen for pH using wide range litmus pH paper or other equivalent pH test
kits within 15 minutes of sample collection. If in any reporting year a Discharger
has two or more pH results outside of the range of 6.0 – 9.0 pH units, that
Discharger is required to comply with the approved test methods in 40 Code of
Federal Regulations part 136 in subsequent reporting years.

For almost all Dischargers, obtaining laboratory analysis within 15 minutes is
logistically impossible. For many Dischargers, maintaining a calibrated pH meter
is difficult, labor intensive, and error prone. Screening for pH will limit the number
of additional Dischargers required to comply with 40 Code of Federal Regulations
part 136 methods to those that have pH measures outside the range of 6.0-9.0
pH units. The use of wide range litmus pH paper or other equivalent pH test kits
is not as accurate as a calibrated pH meter, however litmus paper is allowed in
the 2008 MSGP, and when used properly it can provide an accurate screening
measure to determine if further more-accurate pH sampling is necessary to
determine compliance.

Review of available monitoring data shows that storm water discharges from
most types of industrial facilities comply with the pH range of 6.0 to 9.0 pH units.
There are specific types of industries, like cement or concrete manufacturers that

Order 2014-0057-DWQ 52