City of Flagstaff

Flagstaff Stormwater Laws and Regulations

City of Flagstaff regulations are compliant with its Arizona Pollutant Discharge and Elimination System (AZPDES) permit requirements for the city's small municipal separate storm sewer system (MS4), which became effective September 30, 2016, and with those of Coconino County.

Excerpt- General Permit for Stormwater Discharges from Small Municipal Separate Storm Sewer Systems Permit Number AZG2016-002

9. Post Construction Stormwater Water Management in New Development and Re-Development (Part 6.4.5)

This control measure requires the MS4 to continue to review and enforce a program to address post construction stormwater runoff from areas of new development and redevelopment that disturb one (1) or more acres. Permittees must implement an ordinance or other regulatory mechanism to manage post construction stormwater runoff in to the MS4. This measure applies in areas of new development and redevelopment of construction activities that disturb one (1) acre or more. The long term objective of this measure is to have the hydrology associated with new development closely mirror the predevelopment hydrology and to improve the hydrology of redeveloped sites. Studies have indicated that prior planning and design for minimizing pollutants in post construction stormwater discharges is the most cost effective approach to stormwater quality management. Post construction stormwater runoff may cause two (2) types of impacts. One is an increase in the type and the quantity of pollutants. The alteration of the land by development can increase the discharge of pollutants such as oil and grease, heavy metals, and nutrients, and by high stormwater velocity runoff. A trend in Arizona has been to retain a large portion of stormwater onsite which has the potential to reduce the amount of stormwater that reaches streams, rivers, and lakes. This reduction in runoff reaching water bodies can also negatively impact riparian ecosystems and hydrologic resources. The intent of the permit and this part of the permit is to reduce pollutant loads in stormwater runoff and also reduce runoff velocity. The MS4’s post construction stormwater runoff program should focus on building codes, ordinances, allowances, credits and other measures to ensure and promote the concept that post-construction stormwater runoff be similar to pre-construction stormwater runoff in quality, quantity, and velocity. Management of stormwater can be accomplished in many ways. Low Impact Development (LID) focuses on using practices that imitate the natural water cycle. Rather than directing stormwater to a pipe or conveyance, the stormwater is managed onsite. LID practices can work at the site level as well as the watershed level. The permit requires the permittee to evaluate existing local regulations and make determinations as to whether the existing local regulations allow LID practices and what changes could be adopted to better promote LID practices.

10. Pollution Prevention and Good Housekeeping for Municipal Operations (Part 6.4.6)

This part of the permit applies to municipal facilities that are not otherwise subject to separate stormwater permitting (i.e., industrial activities subject to coverage under Arizona’s Multi-Sector General Permit, MSGP). Some municipal facilities are not currently subject to a separate stormwater permit (e.g., facilities that primarily work on police cars, fire trucks, and others associated with justice, public order, and safety). Municipal facilities are subject to MSGP coverage if it resembles a kind of facility with a Standard Industrial Classification (SIC) code that is covered by the MSGP (e.g., bus maintenance yard, airport maintenance facility), see 40 CFR 122.26(b)(14). ADEQ’s approach to permitting applicability for municipal facilities that conduct a mix of covered/not covered vehicles is to assess if more than 50% of the activities conducted  at the facility are subject to MSGP coverage. For example, if 55% of the vehicle maintenance conducted at the municipal facility is on equipment associated with police cars, fire trucks, and other equipment associated with justice, public order, and safety, then the facility is subject to the MS4 permit. However, if 55% of the activities are associated with garbage trucks, snow plows, and similar/other equipment, then the facility is subject to separate permitting under Arizona’s MSGP. See also 40 CFR 122.26(b)(14) which states “Industrial facilities (including industrial facilities that are federally, State, or municipally owned or operated that meet the description of the facilities listed in paragraphs (B)(14)(i) through (xi) of this section) include those facilities designated under the provisions of paragraph(a)(1)(v) of this section.” This measure requires small MS4s to develop and implement an operations and maintenance program that includes facility inspections and employee training. The ultimate goal of this measure is preventing or reducing pollutant runoff from all municipal operations. The permit includes the minimum requirements for the implementation of this control measure. As part of the evaluation, the permittee must consider and include all facilities that are a source of stormwater pollutants. The permittee should evaluate the use and storage of petroleum products, management of dumpsters, and other wastes. Examples of typical municipal facilities or activities subject to this permit part include: parks and open spaces, fire stations, police stations, buildings and facilities, roadways, storm systems, schools, festivals, and public events. Each municipal facility or activity will require a different set of control measures depending on the nature of activities that occur there and the types of materials or pollutant sources. Developing and maintaining a site-specific Standard Operating Procedure (SOP) for each facility will help to ensure that employees responsible for facility operation are aware of the stormwater controls required for the site. The best way to avoid pollutant discharges from these sources is to keep precipitation and runoff from coming into contact with pollutant sources. The permittee must establish and implement maintenance schedules and inspection frequencies for all permittee-owned facilities or activities subject to operation and maintenance and pollution prevention activities. This permit requires the permittee to develop a facility / activity risk priority schedule for operations, maintenance, and inspections. The inspection frequency may include daily site walks to ensure material are properly stored, equipment is operating as designed, and personnel are following established procedures. For the program to be effective, permittees should develop a Stormwater Pollution Prevention Plan (SWPPP) or similar document for each municipal facility. A boilerplate can be utilized for basic information, but then tailored to each facility for specific needs. The SWPPP should include BMPs implemented at each facility or discharge activity, facility listing, stormwater inspection frequency, staff training topics and frequency, and spill prevention and response procedures. The regulations found at 40 CFR 122.34(b)(6) specifically require the permittee to develop a “training component” that trains employees “to prevent and reduce stormwater pollution from activities such as park and open space maintenance, fleet and building maintenance, new construction and land disturbances, and storm water system maintenance.” This permit requires employee training for existing and new employees who are involved in performing pollution prevention and good housekeeping practices. All training must include a general stormwater educational component, including an overview of the requirements with which the municipality needs to comply. The permittee is responsible for identifying which staff must attend trainings based on the applicability of the topics listed, and conduct initial and refresher training. If the permittee uses third-party contractors to conduct municipal maintenance activities in lieu of using municipal employees, those contractors performing activities that can affect stormwater quality must be held to the same standards as if the permittee uses its own personnel. Not only must these expectations be defined in contracts between the permittee and its contractors, but the permittee is responsible for ensuring, through contractually-required documentation or periodic site visits, that contractors are using stormwater controls and following standard operating procedures. The permittee must include documentation of facility inspections, training sessions, and related information in the annual report.


Flagstaff Stormwater Page

Flagstaff MS4 Factsheet