NPDES Phase II MS4 Permit Process

Before beginning to select BMPs and Measurable Goals, City staff undertook a self-assessment of our storm water system. Representatives from the firm Bonestroo, Rosene, Anderlik and Associates met with City of Centerville staff to facilitate and document the self-assessment process. The self-assessment meeting was conducted on January 17, 2003. This was an evaluation of our city's conditions, needs, and practices. The objective of this process was to provide a knowledge base upon which to structure our SWPPP in order to meet the Permit's Maximum Extent Practicable standard. Details of this process are presented below.

Details of the Self-Assessment Process

The self-assessment was guided by materials included in the League of Minnesota Cities NPDES Phase II MS4 Guide Plan. This self-assessment process had two major components:

The first workshop session organized by the LMC Guide Plan project included a self-assessment component led by Pat Collins of AMEC Earth and Environmental. This included:

• discussion of watershed and organizational conditions and issues that should guide the selection of BMPs and Measurable Goals
• two examples of cities with different characteristics to demonstrate how local conditions should shape the selection of BMPs and Measurable Goals
• a series of exercises in which our city staff was encouraged to consider the local conditions for our community and how they should guide our selection of BMPs and Measurable Goals.

After the workshop session, we worked with our consultant (Bonestroo) to review and discuss the questions in the NPDES Phase II Self-Assessment chapter that was included in the LMC Guide Plan notebook. This thirty-five page chapter served as the basis for a comprehensive list of questions to guide us through a self-assessment activity that included consideration of a wide range of stormwater approaches.

The results of this process include a set of understandings among city staff and written notes that together represent knowledge of our local stormwater system and the conditions that shape it. We have used the results of this self-assessment process to guide our selection of BMPs and Measurable Goals that make up the SWPPP for our Permit Application.

Based on this self-assessment process, our staff has considered the following, as well as additional, factors in order to meet the Maximum Extent Practicable standard set forth in the Permit:

• sources of pollutants
• potentially polluting activities being conducted in the watershed
• sensitivity of receiving waters
• uses of receiving waters
• specific local concerns
• the size of our community
• climate
• implementation schedules
• current ability to finance
• stormwater programs
• hydrology
• geology
• capacity to perform operation and maintenance
• local land uses
• rate and type of development
• characteristics of our watershed
• organizational characteristics of our city

In addition to the self-assessment process discussed above, our staff has also considered the following non-stormwater discharges to determine whether they should be identified as significant contributors of pollutants to our stormwater system:

• water line flushing
• landscape irrigation
• diverted stream flows
• rising ground waters
• uncontaminated ground water infiltration
• uncontaminated pumped ground water
• discharges from potable water sources
• foundation drains
• air conditioning condensation
• irrigation water
• springs
• water from crawl space pumps
• footing drains
• lawn watering
• individual residential car washing
• flows from riparian habitats and wetlands
• dechlorinated swimming pool discharges
• street wash water
• discharge or flows from fire fighting activities.

Through self-assessment, none of the non-stormwater discharges were considered as significant contributors of pollutants to the stormwater system.

Permit Completion

The self-assessment process led to the development of appropriate BMPs and measurable goals for the City. A subsequent meeting on February 28, 2003 was conducted wherein the existing BMPs were finalized. Once existing BMPs were finalized, a preliminary SWPPP was assembled and gaps were identified. A gap memo was prepared which made a comparison with permit requirements and existing programs. Perceived gaps were filled with additional BMPs. After consultation with the City a final, complete SWPPP was finalized. The final SWPPP included both existing and proposed BMPs, responsible persons as well as a timeline for implementation.