Page 107 - California Stormwater Workshop Handouts

Industrial General Permit Fact Sheet

source discharges, and therefore must comply with effluent limitations that are
“consistent with the assumptions and requirements of any available waste load
allocation for the discharge prepared by the State and approved by EPA pursuant to 40
Code of Federal Regulations section 130.7.” (40 C.F.R. § 122.44, subd. (d)(1)(vii).) In
addition, Water Code section 13263, subdivision (a), requires that waste discharge
requirements implement relevant water quality control plans. Many TMDLs in existing
water quality control plans include both waste load allocations and implementation
requirements. Attachment E of this General Permit lists the watersheds with U.S. EPA-
approved and U.S. EPA-established TMDLs that include TMDL requirements for
Dischargers covered by this General Permit.

NPDES-regulated storm water discharges (which include industrial storm water) must
be addressed by waste load allocations in TMDLs. (40 C.F.R. § 130.2(h).) NPDES
permits must contain effluent limits and conditions consistent with the requirements and
assumptions of the waste load allocations in TMDLs. (40 C.F.R. § 122.44(d)(1)(vii)(B).)
To date, the relevant waste load allocations assigned to industrial storm water
discharges are not directly translatable to effluent limitations. Many of the TMDLs lack
sufficient facility specific information, discharge characterization data, implementation
requirements, and compliance monitoring requirements. Accordingly, an analysis of
each TMDL applicable to industrial storm water discharges must to be performed to
determine if it is appropriate to translate the waste load allocation into a numeric effluent
limit, or if the effluent limit is to be expressed narratively using a BMP approach. U.S.
EPA recognizes that because storm water discharges are highly variable in frequency
and duration and are not easily characterized, it is often not feasible or appropriate to
establish numeric limits. Variability and the lack of data available make it difficult to
determine with precision or certainty actual and projected loadings for individual
Dischargers or groups of Dischargers.

Regardless of whether the effluent limit is to be numeric or narrative, the existing waste
load allocations must be carefully analyzed, and in many cases translated, to determine
the appropriate effluent limitations. Issues of interpretation exist with all of the waste
load allocations applicable to Dischargers, and these issues vary based on the TMDL.
Below is an example of one of the simpler issues:

FIGURE 1: Example Waste Load Allocations Proposed Translation: Ballona
Creek Estuary – Toxic Pollutants

Metals per Acre Waste Load Allocations for Individual General

Construction or Industrial Storm Water Permittees (grams/year/acre)

Cadmium Copper Lead Silver Zinc

0.1 3 4 0.1 13

Metals per Acre Waste Load Allocations for Individual General

Construction or Industrial Storm Water Permittees

(milligrams/year/acre)

Chlordane DDTs Total Total Polycyclic aromatic

Polychlorinated hydrocarbons (PAHs)

biphenyl (PCBs)

0.04 0.14 2 350

Order 2014-0057-DWQ 23