Page 124 - California Stormwater Workshop Handouts

Industrial General Permit Fact Sheet

infeasible to comply with this General Permit’s monitoring while activities are
suspended (e.g. remote, unstaffed, or inaccessible facilities during the time of
such a suspension). Dischargers are required to update the facility’s SWPPP
with the BMPs being used to stabilize the site and submit the suspension dates
and a justification for the suspension of monitoring via SMARTS.

3. Design Storm Standards for Treatment Control BMPs

It is the State Water Board’s intent to minimize the regulatory uncertainty and costs
concerning treatment control BMPs in order to encourage the implementation of
treatment control BMPs when appropriate. Section X.H.6 of this General Permit
specifies a design storm standard for use when treatment controls BMPs are
installed. There is both a volume-based and flow-based design storm standard in
this General Permit. Both are based on the 85th percentile 24-hour storm event.
Without a design storm standard, Dischargers have installed treatment controls
using a wide variety of designs that were sometimes either unnecessarily
stringent/expensive, or deficient in complying with the requirements of the relevant
permit. Some Dischargers have been hesitant to consider treatment options
because of the uncertainty concerning acceptable treatment design. The design
storm standards are generally expected to:

 Be consistent with the effluent limitations of this General Permit;

 Be protective of water quality;

 Be achievable for most pollutants and their associated treatment technologies;
and,

 Reduce the costs associated with treating industrial storm water discharges
beyond the levels necessary to achieve compliance with this General Permit.

In lieu of complying with the design storm standards for treatment control BMPs,
Dischargers may certify and submit a Level 2 ERA Technical Report, including an
Industrial Activity BMPs Demonstration (Section XII.D.2.a of this General Permit).
The Level 2 ERA Technical Report requirement is based upon NAL exceedances.
Under this option, a Discharger with Level 2 status must either implement BMPs to
eliminate future NAL exceedances, or justify what BMPs must be implemented to
comply with this General Permit even if the BMPs will not eliminate future
exceedances of NALs. Dischargers who implement treatment control BMPs that
vary from the design storm standards in Section X.H.6 must include an analysis
showing that their treatment control BMPs comply with this General Permit’s effluent
limitations in the Industrial Activity BMP Demonstration.

This General Permit does not require Dischargers to retrofit existing treatment
controls that do not meet the design storm standard, unless the Discharger
determines that the existing treatment controls are not adequate to comply with this
General Permit. In addition, once TMDL-specific implementation requirements are
added to this General Permit, those Dischargers subject to TMDLs may need to add

Order 2014-0057-DWQ 40