AA. Fabricated Metal Products

1. Authorized Stormwater Discharges

The requirements in Sector AA apply to stormwater discharges associated with industrial activity from fabricated metal products facilities as identified by the industrial activity code specified in Table 5 of Appendix D.

2. Industrial Activities Authorized by Sector AA

Permittees under Sector AA are primarily engaged in the following types of activities:

a. Fabricated metal products, except machinery and transportation equipment and cutting.

b. Jewelry, silverware, and plated ware.

c. Fabricated metal coating, engraving, and allied services.

3. Limitations on Authorization (No Additional Limitations)

4. Sector-Specific Definitions (No Additional Definitions)

5. Stormwater Controls

a. Employee Training (No additional requirements).

b. Erosion and Sedimentation Controls (No additional requirements).

c. Good Housekeeping.

1. The Permittee shall describe and implement measures for controlling or recovering scrap metals, fines, and metal dust. The Permittee shall include measures for containing materials within storage and handling areas.

2. The Permittee shall describe and implement measures for storage of metal working fluids.

d. Inspections.

1. The Permittee shall inspect the following areas where the potential for exposure to stormwater exists:

a. Areas associated with spent solvents.

b. Chemical storage areas.

c. Outdoor paint areas.

2. In addition to the inspection requirements outlined in Part III.G, the Permittee shall ensure that a total of two (2) of the required monthly inspections occur during runoff events, with at least one being performed during snow melt. Each inspection shall 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. If sheens are present in stormwater discharges, corrective actions to prevent sheen shall be implemented and documented in the SWPPP.

The Permittee is only required to conduct visual inspections of runoff originating from, or passing through, areas of industrial activity and/or significant materials. Any runoff that does not contact industrial activity and/or significant materials (e.g. office buildings, employee parking lots, natural areas, etc) is not required to be inspected.

e. Preventive Maintenance.

The Permittee shall describe and implement measures to prevent or minimize exposure of paint and painting equipment to stormwater.

f. Spills and Leaks.

1. The Permittee shall 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.

2. The Permittee shall use monitoring equipment or other devices to detect and control leaks and overflows of lubricating oil and hydraulic fluid. The Permittee shall install perimeter controls or equivalent measures.

g. Management of Runoff (No additional requirements).

h. Other Stormwater Control Measures (No additional requirements).

6. SWPPP Requirements

In addition to the requirements of Part IV, the Permittee shall also comply with the following:

a. Facility Map.

The Permittee shall identify where any of the following may be exposed to stormwater:

1. Raw metal storage areas.

2. Finished metal storage areas.

3. Scrap disposal collection sites.

4. Retention and detention basins.

5. Temporary and permanent diversion dikes or berms.

6. Right-of-way or perimeter diversion devices.

7. Sediment traps and barriers.

8. Processing areas, including outdoor painting areas.

9. Wood preparation.

10. Recycling.

11. Raw material storage.

b. Inventory of Exposed Materials (No additional requirements).

c. Potential Pollutant Sources.

The Permittee shall describe the following additional sources that have potential pollutants associated with them. Potential pollutants include chromium, zinc, lubricating oil, solvents, aluminum, oil and grease, methyl ethyl ketone, steel, and related materials.

1. Operations for paints, chemicals, and scrap metals.

2. Outdoor manufacturing or processing activities such as grinding, cutting, degreasing, buffing, and brazing.

3. On-site waste disposal practices for spent solvents, sludge, pickling baths, shavings, ingot pieces, and refuse and waste piles.

d. Description of Stormwater Controls (No additional requirements).

7. Monitoring and Reporting Requirements In accordance with the monitoring requirements of Part V, the Permittee shall monitor the applicable parameters in Table AA-1, below:

Sector-Specific Benchmark Values and Effluent Limitations: Sector - AA: Discharges may be subject to requirements for more than one sector or subsector.

Link to this table

Subsector Parameter Benchmark Values
AA1 Fabricated Metal Products Aluminum, Total (as Al) 1.5 mg/L
Iron, Total (as Fe) 1.0 mg/L
Zinc, Total (as Zn) 0.234 mg/L 1
Solids, Total Suspended (TSS) 100 mg/L 2
AA2 - Fabricated Metal Coating and Engraving Zinc, Total (as Zn) 0.234 mg/L 1
Solids, Total Suspended (TSS) 100 mg/L 2

1The benchmark values of some metals are influenced by water hardness. For these parameters, the Permittee may determine the hardness of the stormwater discharges to identify the applicable ‘hardness range’ for determining their benchmark value. See Table 4 of Appendix B for hardness dependent benchmark values in accordance with Minn. R. 7050.0222 and Minn. R. 7052.0100.
2If the Permittee is required to comply with Appendix A, part F.1, the benchmark value for Solids, Total Suspended (TSS) is 65 mg/L, instead of 100 mg/L.


8. Use of Infiltration Devices and/or Industrial Stormwater Ponds for Stormwater Treatment and Disposal

Sector AA industrial facilities are authorized to use designed infiltration devices or industrial stormwater ponds for stormwater management.

This page was last edited on 30 April 2015, at 20:15.