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Indiana Department of Environmental Management

IDEM > Permitting > Water Permits > Storm Water Permitting > Industrial Storm Water Permitting (327 IAC 15-6, Rule 6) > Rule 6 Definitions Rule 6 Definitions

Industrial facilities generally are classified by Standard Industrial Classification (SIC) Code. This code is a four-digit number that corresponds to the primary type of industrial activity at a facility, and can be determined, on-line, from the OSHA web page. Facilities who are currently using the North American Industry Classification System (NAICS) can find conversion tables into SIC Code at the following web site Several of the SIC Codes and some additional non-classified industrial activity categories are subject to Rule 6. The following table describes the industrial SIC Code categories subject to Rule 6:

Regulated Industrial Activity Categories
SIC Code * Activity Description
10xx Metal mining
13xx Oil and gas extraction
14xx Nonmetallic minerals, except fuels
20xx Food and kindred products
21xx Tobacco products
22xx Textile mill products
23xx Apparel and other textile products
24xx Lumber and wood products
25xx Furniture and fixtures
26xx Paper and allied products
27xx Printing and publishing
28xx Chemicals and allied products
29xx Petroleum and coal products
30xx Rubber and miscellaneous plastic products
31xx Leather and leather products
32xx Stone, clay, and glass products
33xx Primary metal industries
34xx Fabricated metal products
35xx Industrial machinery and equipment
36xx Electronic and other electric equipment
37xx Transportation equipment
38xx Instruments and related products
39xx Miscellaneous manufacturing industries
40xx Railroad transportation
41xx Local and interurban passenger transit
42xx Trucking and warehousing
43xx United States Postal Service
44xx Water transportation
45xx Transportation by air
5015 Motor vehicle parts, used
5093 Scrap and waste materials
5541 Gasoline service stations **

* Although the actual SIC Code is a four-digit number, Rule 6 regulates the primary category group (i.e., the first two digits of the SIC Code) in many cases.

** Only gasoline service stations that act as truck stops or plazas and have on-site vehicle maintenance activities are potentially regulated under Rule 6.

In addition to SIC Code designation, several narrative categories of industrial activities are also potentially regulated under Rule 6. These narrative categories include:

  1. hazardous waste treatment, storage, or disposal facilities;
  2. landfills, land application sites, open dumps, and transfer stations;
  3. steam electric power generating facilities;
  4. wastewater treatment plants with a design flow of 1,000,000 gallons per day or more; and
  5. agricultural chemical fertilizer and pesticide distribution facilities.

Conditional No Exposure Exclusion

To claim the no exposure exclusion, certification form #3510-11 [PDF] must be completed and submitted to IDEM. U.S. EPA created the form, and, on the form, it states that the form should be returned to U.S. EPA. However, since IDEM acts as the NPDES permitting authority for U.S. EPA in Indiana, the federal form must be submitted to:

IDEM-Office of Water Quality
Rule 6 Storm Water Coordinator
100 North Senate Avenue, Room 1255
Indianapolis, IN 46204

Because IDEM is the agency tasked with granting the exclusions in Indiana, the submittal of this form to EPA will only delay the acceptance of the exclusion. To maintain the status of the exclusion after five years, facility representatives must resubmit a completed form at least 90 days prior to the five-year anniversary date of the previous exclusion form submittal.

A copy of the completed exclusion form must be retained at the facility for a period of 5 years following the date that IDEM received the original form. If the facility has an ownership change, the exclusion form is also nontransferable, and a new form must be completed and submitted to IDEM.

If unforeseen events, such as spills, equipment malfunctions, or acts of nature, cause industrial activities or materials to become exposed to stormwater, the no exposure exclusion may still apply provided notification is given to IDEM within 24 hours of facility personnel becoming aware of the exposure and corrective measures are taken to reestablish a condition of no exposure prior to the next stormwater discharge event.

Stormwater Pollution Prevention Plan Checklist

Once an NOI letter is submitted, facility representatives will have 365 days to develop, revise, and implement a Storm Water Pollution Prevention Plan. A completed checklist form (available on the IDEM Forms page) must be submitted to IDEM within the 365 days. The checklist form must be signed by a "qualified professional." According to rule definition, "qualified professional means an individual who is trained and experienced in stormwater treatment techniques and related fields as may be demonstrated by state registration, professional certification, experience, or completion of coursework that enable the individual to make sound, professional judgments regarding stormwater control or treatment and monitoring, pollutant fate and transport, and drainage planning."

The actual Stormwater Pollution Prevention Plan (SWP3) should not be submitted to IDEM, unless a representative from IDEM requests the document. Instead the actual SWP3 must be retained at the facility, and available for review during an on-site inspection. The SWP3 must be reviewed periodically, and updated as relevant conditions at the facility change.

The SWP3 can be combined with other written facility plans, such as operation and maintenance, spill prevention control and countermeasures, or risk contingency plans, if those plans fulfill the requirements of a Rule 6 SWP3. It is required that the other plans, if used, have a separate, labeled section for the SWP3. Otherwise, a separate SWP3 should be developed, and, as an alternative, the relevant information in the other facility plans could be referenced in the SWP3 (e.g., the spill reporting procedures and reporting contact information are available in section 4 of the facility Spill Contingency Plan, etc.).

If IDEM notifies a facility representative that their SWP3 is ineffective or deficient, a facility representative must make the required changes to the SWP3 and submit the amended plan within 60 days of the written notification.

Qualified Rainfall Events

There must be at least 3 calendar months between reported outfall discharge sampling events. All samples must be collected from a discharge resulting from a measurable storm event at least 72 hours from the previous measurable storm event. According to rule definition, "measurable storm event means a precipitation event which results in a total measured precipitation accumulation equal to, or greater than, one-tenth (0.1) inch of rainfall." Therefore, if it rains more than 0.1 inch (measured by on-site rainfall gauge or local/regional rain gauges) and it has been more than 72 hours since the last rainfall of 0.1 inch or more, then the sampling data collected during the rainfall event can be used to represent stormwater quality from the facility outfalls.

Sampling Parameters

Facility representatives must sample the stormwater discharges at all representative facility outfalls. Grab samples are required, and a grab sample must be collected during the first 30 minutes of discharge at the stormwater outfalls or as soon thereafter as practicable. Analyses for the following parameters are required:

  1. Oil and grease
  2. Carbonaceous biochemical oxygen demand (CBOD)
  3. Chemical oxygen demand (COD)
  4. Total suspended solids (TSS)
  5. Total Kjeldahl nitrogen (TKN)
  6. Total phosphorous
  7. pH
  8. Nitrate plus nitrite nitrogen
  9. Any pollutant attributable to a facility's industrial activity which is reasonably expected to be present in the discharge
  10. Any pollutant that has the potential to be present in a stormwater discharge as requested by IDEM

Samples must be collected at least annually, with the first sample collected prior to implementation of the Storm Water Pollution Prevention Plan. Storm water outfall sample data collected more frequently than annually must be reported to IDEM. The pH measurement must be taken at the time the grab sample is collected (i.e., due to holding time exceedances, pH can not be analyzed by an off-site laboratory), and can not be estimated using a color comparison (i.e., test strips).

Samples must be taken at a point representative of the discharge but prior to entry into surface waters of the state or a storm sewer conveyance. For discharges that flow through on-site detention basins, samples must be taken at a point representative of the discharge from the basin. Run-off events resulting from snow or ice melt should not be sampled and can not be used to meet the annual monitoring requirements of Rule 6. Additional stormwater sampling guidance [PDF] is available from EPA.

Sampling data results must be submitted to IDEM within 30 days after the completion of laboratory analyses. If requested, a copy of the sampling data results must be submitted or available to the operator of a municipal separate storm sewer system into which the facility discharges.

Changing Facility Ownership

Rule 6 permits and no exposure exclusions are nontransferable. If a facility comes under new ownership, representatives from the previous ownership (i.e., permit holder) must submit a Notice of Termination request within 30 days of the transfer. The new ownership must then apply for Rule 6 coverage or the no exposure exclusion within 60 days after the transfer.

Rule 6 Notice of Termination

A Notice of Termination (NOT) letter must be submitted to IDEM if the facility is:

  1. closing;
  2. transferring ownership;
  3. seeking a no exposure exclusion (only applicable for current Rule 6 general stormwater permittees);
  4. directing all its stormwater into a combined sewer system; or
  5. claiming stormwater does not have the potential to impact a water of the state (e.g., stormwater run-off is directed to lined, on-site retention basins).

An NOT request due to closure or ownership transfer must be submitted within 30 days of the date of closure or transfer. For facility representatives seeking a no exposure exclusion, the NOT request letter must be submitted with a completed conditional no exposure certification form [PDF]. For facility representatives claiming that stormwater run-off is directed to a combined sewer system, the NOT request letter must be submitted with a certification letter from the responsible party of the combined sewer system, on responsible party letterhead.

NOI Letter Submittal

If a facility is subject to Rule 6, facility representatives must submit an NOI letter (available on the IDEM Forms page), a proof of publication, and a $50-filing fee check or money order to IDEM either after notification by IDEM or prior to beginning industrial activities at the facility.

Obtaining Facility Longitude and Latitude Coordinates

The Rule 6 NOI letter form contains instructions in Appendix A (page 4). These instructions pertain to obtaining coordinates from a United States Geological Survey (USGS) quadrangle or topographic map. The maps can be accessed through a locational web site and conducting a search based on the facility street address. The coordinates may be provided in decimals, and will need to be converted into degrees, minutes, seconds prior to completing the NOI letter form (refer to Appendix A, "Part A, Item #4 Example" on how to convert the coordinates).

MS4 Entity Information

Municipal Separate Storm Sewer System (MS4) entities are cities, towns, counties, colleges, universities, correctional facilities, homeowner's associations, conservancy districts, military bases, and hospitals that have responsibility for maintaining or operating a stormwater conveyance or system of conveyances. On the NOI letter form for Rule 6, the facility representative must list the MS4 entity or entities where the facility is located.

The City of Indianapolis acts as the principal MS4 entity for stormwater run-off control within Marion County (excluding the Cities of Beech Grove, Lawrence, Southport and Speedway). Several additional MS4 entities are regulated under 327 IAC 15-13 (Rule 13). If an industrial facility is located within the jurisdictional boundaries of one, or more, of these MS4 entities subject to Rule 13, the facility may also need to comply with local run-off control requirements. An MS4 entity listing for those entities regulated under Rule 13 and additional information about the requirements placed on these entities are available from the Rule 13 web page.

Proof of Publication

A proof of publication in a newspaper of general circulation in the area where the facility is located must be included with the NOI letter submittal. According to 327 IAC 15-6-5(8), the public notice must state "(Facility name, address, address of the location of the discharging facility, and the stream(s) receiving the discharge(s)) is submitting an NOI letter to notify the Indiana Department of Environmental Management of our intent to comply with the requirements under 327 IAC 15-6 to discharge stormwater exposed to industrial activities." Notices without the proper information will not be sufficient, and IDEM will require that a new notice be placed in the newspaper. The actual proof of publication from the newspaper should be submitted. If the proof of publication is not available, a legible photocopy of the article, along with the name of the newspaper and the date(s) that the article was run is also acceptable.

As additional assistance, the following hypothetical public notice language can be used as an example:

"Xert Industries (with corporate offices at 10 Willow Lane, Indianapolis, Indiana 46206) is submitting an NOI letter for our facility (located at 5 South Wet Street, Indianapolis, Indiana 46206) to notify the Indiana Department of Environmental Management of our intent to comply with the requirements under 327 IAC 15-6 to discharge stormwater exposed to industrial activities. Run-off from the facility will discharge to the White River. Questions or comments should be directed to Walter Water at the above mentioned Xert Industries corporate address."