Saturday, April 4, 2009

Fabricated Metal Products Sector - SWPPP - Stormwater Permit Proposed Requirements

On July 6, 2009, the Minnesota Pollution Control Agency released its proposed multisector industrial stormwater discharge general permit. This permit, once promulgated, will replace the existing industrial stormwater permit, which expired in October of 2002.

[Read a summary of the overall Minnesota permit, stormwater monitoring, and sector requirements]

Caltha LLP will be conducted seminars on the proposed sector requirements in July & August 2009. Caltha MPCA Industrial Stormwater Permit Requirements Seminars

The proposed permit details requirements for 29 different industrial sectors. The requirements described below are proposed for the Fabricated Metal Products Sector (Sector AA). Sector AA facilities include fabricated metal products (except machinery and transportation equipment) jewelry, silverware, and plated ware, and fabricated metal coating, engraving and allied services. These requirements are in addition to permit requirements that apply to all sectors.

The facility must conduct inspections addressing areas associated with spent solvents, chemical storage areas, and outdoor paint areas.

In addition to routine inspection requirements, the operation must conduct two of the monthly inspections during runoff events. One of the inspections must be performed during a snow melt runoff event. Each inspection must include a visual assessment of the runoff to identify any visible sheens or films that indicate the presence of oil or grease in the discharge.

Good Housekeeping:
The pollution prevention program must implement measures for controlling or recovering scrap metals, fines, and metal dust. The SWPPP must include measures for containing materials within storage handling areas. The SWPPP must describe and implement measures for storage of metal working fluids.

Leaks and Spills:
The spill prevention program must address chromium, toluene, pickle liquor, sulfuric acid, zinc and other water priority chemicals, and hazardous chemicals and wastes.

The spill prevention plan must describe and implement measures to control and clean up spills of solvents and other liquid cleaners, control sand buildup and disbursement from sand-blasting operations, and prevent exposure of recyclable wastes including rinse waters. Each operation must use monitoring equipment or other devices to detect and control leaks and overflows of lubricating oil and hydraulic fluid operations and install perimeter controls, or equivalent measures.

Stormwater Monitoring Benchmarks:
All facilities are required to conduct visual and chemical (benchmark) monitoring. For benchmark monitoring, the benchmark concentrations or values depend on product type:

Fabricated Metal Products, (SIC 3411-3499; 3911-3915)
TSS 100 mg/L
Total Aluminum 1.5 mg/L
Total Iron 1.0 mg/L
Total Zinc 0.234 mg/L

Fabricated Metal Coating and Engraving (SIC 3479):
TSS 100 mg/L
Total Zinc 0.234 mg/L

Note: Benchmarks for zinc and iron were derived based on the Aquatic Life Standards for these parameters in Minnesota Rules.

[Read more about use of Aquatic Life Standards to derive stormwater benchmarks]
[Read more about how benchmarks are used under the proposed MPCA industrial permit]
[Read more about what a 100 mg/L benchmark for TSS relates to]

Looking for other sector information? Click here for a link to all sector requirements

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP at
Caltha LLP Website

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