NPDES Phase II Enforcement Takes Collaborative Effort

The key to developing stormwater pollution control policies that are enforceable at the local level while complying with federal standards is for local officials and state environmental agencies to build strong working relationships, according to a stormwater authority in Maine.

"Compliance has been outstanding in Maine," said David Ladd, municipal and industrial stormwater coordinator for the Maine Department of Environmental Protection (DEP). "There have been no enforcement cases in the MS4 program," Ladd said.

An MS4 is a separate stormwater sewer system that is owned by a public entity and is not part of a publicly owned treatment works (sewage treatment plant).

The federal Clean Water Act (CWA) prohibits the discharge of any pollutant to navigable waters of the United States from a point source unless the discharge is authorized by a National Pollutant Discharge Elimination System (NPDES) permit.

"Efforts to improve water quality under the NPDES program traditionally have focused on reducing pollutants in industrial process wastewater and municipal sewage treatment plant discharges," the U.S. Environmental Protection Agency (EPA) reports.

"Over time, it has become evident that more diffuse sources of water pollution, such as stormwater runoff from construction sites, are also significant contributors to water quality problems."

In 1990, the EPA promulgated rules establishing Phase I of the NPDES stormwater program. Phase I addresses, among other discharges, those from construction activities that disturb 5 acres or more of land. Phase II covers construction activities that disturb between 1 and 5 acres of land. Phase II became final in 1999 and small construction permit applications were due by March 10, 2003 (specific compliance dates were to be established by the NPDES permitting authority in each state).

Under Phase II, site activities disturbing less than 1 acre are also regulated as small construction activity if they are part of a larger common plan of development or sale with a planned disturbance that is 1 acre to less than 5 acres, or if they are designated by the NPDES permitting authority, according to the EPA.

"The NPDES permitting authority or EPA Region may designate construction activities disturbing less than 1 acre based on the potential for contribution to a violation of a water quality standard or for significant contribution of pollutants to waters of the United States," the EPA reports.

Phase II requires operators of qualified small construction sites, nationally, to obtain an NPDES permit and implement practices to minimize pollutant runoff, according to the EPA.

Locally, these same sites may be covered by state, tribal, or local construction runoff control programs. The Phase II small construction program requirements are not fully defined in the rule but are defined in the NPDES permit issued by the NPDES permitting authority.

In June 2010, the EPA proposed minor amendments to its CWA regulations that would codify under the NPDES program that only "sufficiently sensitive" analytical test methods can be used when completing an NPDES permit application and when performing sampling and analysis pursuant to monitoring requirements in an NPDES permit.

"EPA is proposing to clarify the existing NPDES application, compliance monitoring, and analytical methods regulations. The amendments in this proposed rulemaking affect only the chemical-specific methods; they do not apply to the Whole Effluent Toxicity (WET) methods or their use," the EPA reports.

"WET tests replicate the total effect and actual environmental exposure of aquatic life to toxic pollutants in an effluent without requiring the identification of the specific pollutants. WET testing is a vital component of the water quality standards implementation through the NPDES permitting process and supports meeting the goals of the Clean Water Act."

The NPDES Phase II program has caused some communities in Maine to better evaluate and understand their stormwater infrastructure, according Ladd. DEP has enforcement authority over the NPDES Phase II program in Maine.

DEP works with municipalities in Maine and the municipalities put together plans that DEP must approve. Some municipalities have plans that target different types of businesses.

"Each municipality that's covered, must have a primary and secondary watershed where I want them to put forth the greatest resources and effort to clean the water," Ladd said.

"Maine's regulated small MS4s are in four clusters. There is about 200 miles from the southern regulated communities to the northern communities/entities (state and federal facilities). Regulated entities within the clusters work well together, transcending municipal/political boundaries to focus on common tasks and problems of MS4 permit compliance. These collaborative efforts, which many times DEP has been a part of, have saved Maine's regulated small MS4s around $750,000 over the past eight years," Ladd said.

"The DEP has conducted audits which have resulted in remedial/corrective actions, but the regulated MS4s have always stepped up to full compliance when corrective actions were required," Ladd said.

The MS4 General Permit enforces the NPDES Phase II program in Maine. Ladd pointed out that the MS4 General Permit is developed through a stake holder process.

Developing the permit takes approximately 18 months and there are approximately 60 drafts of the permit that are vetted through the permittees.

"We do this, because one of the things that I don't want to do is develop a permit that cannot be implemented," Ladd said.

"We've developed mutual respect and trust. There was a fear of DEP, which is no longer evident," he said.

The Maine permitting program is also vetted through the EPA. "EPA sets minimum requirements and, for the most part, we meet the minimum requirements, and at times, we exceed the minimum requirements," Ladd said.

The EPA Office of Wastewater Management says that the major steps for a permit writer to develop and issue an individual NPDES permit are the following:

1. Receive the application from the permittee.

2. Review the application for completeness and accuracy.

3. Request additional information as necessary.

4. Develop technology-based effluent limits using application data and other sources.

5. Develop water quality-based effluent limits using application data and other sources.

6. Compare water quality-based effluent limits with technology-based effluent limits and choose the more stringent of the two as the effluent limits for the permit.

7. Develop monitoring requirements for each pollutant.

8. Develop special conditions.

9. Develop standard conditions.

10. Consider variances and other applicable regulations.

11. Prepare the fact sheet, summarizing the principal facts and the significant factual legal, methodological and policy questions considered in preparing the draft permit including public notice of the draft permit, and other supporting documentation.

12. Complete the review and issuance process.

13. Issue the final permit.

14. Ensure that permit requirements are implemented.

"The process for developing and issuing general NPDES permits is similar to the process for individual permits; however, there are certain differences in the order of events. The permitting authority first identifies the need for a general permit by collecting data demonstrating that a group, or category, of dischargers has similarities that warrant a general permit," the EPA reports. In deciding whether to develop a general permit, permitting authorities take the following into consideration:

• Are there a large number of facilities that must be covered?

• Do the facilities have similar production processes or activities?

• Do the facilities produce similar pollutants?

• Do only a small percentage of the facilities have the potential for violations of water quality standards?

The EPA says waivers are available for operators of regulated small construction activity if they certify one of two conditions:

• Low predicted rainfall potential (i.e., activity occurs during a negligible rainfall period), where the rainfall erosivity factor ("R" in the Revised Universal Soil Loss Equation [RUSLE]) is less than five during the construction activity period; or

• A determination that stormwater controls are not necessary based on either:

(a) A "total maximum daily load" (TMDL) that addresses the pollutant(s) of concern for construction activities; or

(b) An equivalent analysis that determines allocations are not needed to protect water quality based on consideration of in-stream concentrations, expected growth in pollutant concentrations from all sources, and a margin of safety.

The Rainfall Erosivity Factor is used to determine whether the potential for polluted discharge is low enough to justify a waiver from the requirements, the EPA reports. "It is one of six variables used by the RUSLE - a predictive tool originally used to measure soil loss from agricultural lands at various times of the year on a regional basis - to predict soil loss from construction sites. The Rainfall Erosivity Factor waiver is time-sensitive and is dependent on when during the year a construction activity takes place, how long it lasts, and the expected rainfall and intensity during that time," the EPA reports.

When technology-based controls required by NPDES permits are not achieving state water quality standards for polluted waters, the CWA requires implementation of the TMDL process, according to the EPA. The TMDL process sets the maximum amount of pollutants a body of water can assimilate before the water is considered polluted, and it requires that this level not be exceeded.

"A TMDL is done for each pollutant that is found to be contributing to the impairment of a body of water or a segment of a body of water. To allow a waiver for construction activities, a TMDL would need to address sediment, or a parameter that addresses sediment such as total suspended solids, turbidity, or siltation. Additional TMDLs addressing common pollutants from construction sites such as nitrogen, phosphorous, and oil and grease also may be necessary to ensure water quality protection and allow a waiver from the NPDES stormwater program," the EPA reports.

"A TMDL assessment determines the source or sources of a pollutant of concern, considers the maximum allowable level of that pollutant for the body of water, then allocates to each source or category of sources a set level of the pollutant that it is allowed to discharge into the body of water. Allocations to point sources are called wasteload allocations.

"EPA expects that when TMDLs or equivalent analyses are completed, there may be a determination that certain classes of sources, such as small construction activity, would not have to control their contribution of pollutants of concern to the body of water in order for the body of water to be in attainment with water quality standards (i.e. these sources were not assigned wasteload allocations). In such a case, to qualify for a waiver, the operator of the construction site would need to certify that its construction activity will take place, and the stormwater discharges will occur, within the area covered either by the TMDLs or equivalent analysis. A certification form would likely be provided by the NPDES permitting authority for this purpose."