O. Steam Electric Generating Facilities

1. Authorized Stormwater Discharges

The requirements in Sector O apply to stormwater discharges associated with industrial activity from steam electric power generating facilities as identified by the industrial activity code specified in Table 5 of Appendix D.

2. Industrial Activities Authorized by Sector O Permittees under Sector O are primarily engaged in the following types of activities:

a. Steam electric power generation.

b. Dual fuel co-generation facilities producing steam.

3. Limitations on Authorization

The following discharges are not authorized by this permit:

a. Non-stormwater discharges subject to effluent limitations guidelines.

b. Stormwater discharges from ancillary facilities (e.g. gas turbine stations and substations) that are not contiguous to a steam electric power generating facility and heat capture co-generation facilities.

c. Coal pile runoff wastewater. Coal pile runoff wastewater shall be collected and treated separate from other collected stormwater runoff. Discharge of coal pile runoff wastewater is authorized and permitted under an individual NPDES/SDS permit for the facility which includes effluent limitations for this discharge.

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.

The Permittee shall describe and implement procedures to reduce or control the tracking of ash and residue from ash loading areas. The Permittee shall describe and implement housekeeping procedures, such as, dust suppression, containment, or clearing loading areas, floors and roadways of ash and excess water.

d. Inspections.

1. The Permittee shall inspect the following areas:

a. Coal handling areas.

b. Switchyards.

c. Ash handling areas.

d. Areas adjacent to disposal ponds and landfills.

2. The Permittee shall inspect all residue-hauling (e.g. ash) vehicles for proper covering over the load, adequate gate sealing, and overall integrity of the container body. Repair, as soon as practicable, vehicles without load covering or adequate gate sealing, or with leaking containers or beds.

3. 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.

1. The Permittee shall describe and implement measures that prevent or minimize stormwater from contacting fugitive dust emissions from coal handling areas.

2. The Permittee shall describe and implement measures that prevent or minimize contamination of stormwater runoff from delivery vehicles carrying significant materials arriving at the facility. The Permittee shall have procedures ensuring overall integrity of the body or container and procedures to deal with leakage or spillage from vehicles or containers.

3. The Permittee shall describe and implement measures that prevent or minimize contamination of surface runoff from oil-bearing equipment in switchyard areas. Use level grades and gravel surfaces to retard flows and limit the spread of spills from oil-bearing equipment in switchyards, or collect runoff in perimeter ditches from these areas.

f. Spills and Leaks.

The Permittee shall describe and implement measures to reduce the potential for an oil or chemical spill, or reference the appropriate part of the facility SPCC plan. Visually inspect the structural integrity of all above-ground tanks, pipelines, pumps, and related equipment, and conduct any necessary repairs, pursuant to Minnesota tanks program requirements.

g. Management of Runoff.

The Permittee shall describe and implement measures that prevent or minimize contamination of surface runoff from areas adjacent to disposal ponds or landfills. Develop procedures to reduce ash residue that may be tracked on to access roads traveled by residue handling vehicles, and reduce ash residue on exit roads leading into and out of residue handling areas.

h. Other Industry Specific 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 the locations of any of the following activities or sources that may be exposed to stormwater:

1. Scrap yards and general refuse areas.

2. Short- and long-term storage of construction materials, paint equipment, oils, fuels, used and unused solvents, cleaning materials, paint, water treatment chemicals, fertilizer, and pesticides.

3. Landfills and construction sites.

4. Stockpile areas (e.g. coal, ash or limestone piles).

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

c. Potential Pollutants (No additional requirements).

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

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

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

Subsector Parameter Benchmark Values Effluent Limits
O1 Coal Fired and Oil Fired Steam Electric Generating Facilities Solids, Total Suspended (TSS) 100 mg/L 1 Effluent Monitoring Not Required
Iron, Total (as Fe) 1.0 mg/L Effluent Monitoring Not Required
O2 Nuclear, Natural Gas Fired, And Any Other Fuel Source Used For Steam Electric Generation Solids, Total Suspended (TSS) 100 mg/L 1 Effluent Monitoring Not Required
O3 Runoff From Coal Storage Piles At Steam Electric Generating Facilities Solids, Total Suspended (TSS) Benchmark Monitoring Not Required 50 mg/L daily maximum 2
pH Benchmark Monitoring Not Required 6.0 SU, instantaneous minimum 9.0 SU, instantaneous maximum

1If 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.
2If the facility is designed, constructed, and operated to treat the volume of coal pile runoff that is associated with a 10-year, 24-hour rainfall event, any untreated overflow of coal pile runoff from the treatment unit is not subject to the 50 mg/L limitation for total suspended solids.

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

Sector O 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 18:35.


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