© 2020 by Assessment Associates, Inc.

Call us today (503) 233-8565

Storm Water Management

Have you been told that you need a Stormwater Management Plan, or a Facility Operations and Maintenance Plan, or that you need to register the drywells on your property with the Oregon Department of Environmental Quality? We can help with that! Call us today at 503-233-8565.


In the Pacific Northwest, with average annual rainfall amounts routinely totaling 50 to 60 inches per year, typically occurring between the months of October and May, the implementation of stormwater best management practices is a key aspect for any development project.  Stormwater runoff is one of the largest sources of pollutants to waterways across the country.  Stormwater flows over impervious surfaces, as well as lawns and bare soils, and picks up and transports fertilizers, oil and grease, animal waste, and other pollutants. The Environmental Protection Agency has identified improperly managed stormwater runoff as one of the principle causes of water quality impairments and habitat degradation in developed and developing areas.  There is a growing public awareness of this issue nationally and in the Pacific Northwest.

  • To address post construction stormwater pollution, the Oregon Department of Environmental Quality’s 401 Water Quality Certification Program requires a post-construction stormwater management plan (SWMP) be submitted for review and approval by the agency. The plan must be submitted for all projects that require a federal permit or license and that results in an increase or redevelopment of impervious surfaces.  The SWMP applies to post construction permanent stormwater facilities such as constructed wetlands, bioswales, retention ponds, infiltration galleries and drywells.


  • Stormwater facilities that discharge stormwater runoff below the ground surface such as sumps, drywells, and soakage trenches are required to be registered as an Underground Injection Control (UIC) system with the Oregon Department of Environmental Quality.  UIC systems are regulated under the federal Safe Drinking Water Act (administered by DEQ) and the State Plumbing Code. DEQ regulates UICs under the Oregon Administrative Rules 340-40 and 340-44. UICs can pollute soil and groundwater if not properly designed, sited, and operated. In many cases, as site assessment is required to certify that the stormwater UIC system will not be exposed to contaminants.




Stormwater Pollution Prevention Plans


What is a SWPPP (Stormwater Pollution Prevention Plan)?

A Stormwater Pollution Prevention Plan (SWPPP) is a site-specific report that identifies all of the practices, procedures, and materials at a facility that could degrade stormwater quality. The SWPPP itemizes the actions the facility must take to comply with stormwater regulations and prevent unauthorized discharges of contaminated stormwater from flowing offsite.

How does a facility determine if it needs a SWPPP? 

Any facility that discharges polluted stormwater into a waterway, such as a ditch, stream, or river, must obtain a National Pollutant Discharge Elimination System (NPDES) permit. To obtain a permit, a Notice of Intent (NOI) must be submitted to the regulating authority characterizing the types of contaminants, and specifying the name of the waterway receiving the discharge. The facility is then required to develop a SWPPP.

The SWPPP is developed with the cooperation of the facility environmental manager, the regulator, and, often, a stormwater consultant to establish limits and parameters for a wide variety of pollutants, such as grease and oil, metals, pH, temperature, biological oxygen demand, and turbidity. SWPPPs are not required for discharges into a sanitary sewer or Publicly Owned Treatment Works (POTW). However, a POTW may have certain limits or restrictions on volume of discharge or what types of contaminants can be discharged into that system without pre-treatment. Some POTWs may also require special plans or permits for discharges into their system.

What is included in a SWPPP?

A SWPPP primarily focuses on establishing preventative measures for minimizing discharge of pollutants into waterways. However, since spills can and do happen even at well-managed sites, a SWPPP must include a plan for addressing stormwater best management practices with regard to spill response. Specifically, the SWPPP must include: 1) A map and description of the facility; 2) Names and titles of the spill response team; 3) A list of the possible pollution-causing practices performed at the facility; 4) A list of spill and pollution control measures, 5) A detailed spill response plan; 6) A facility inspection/monitoring schedule; and 7) An employee training schedule.


SWPPP Components in Detail: 

1)    Site Description:
In addition to the name and address of the business operating at the facility, the site description includes a detailed diagram clearly depicting the location of stormwater outfalls and potential pollutant discharge points. These details include stormwater flow pathways across the site; the location of stormwater catch basins, drains, or ditches; location of stored chemicals or other potential contaminants; previous spill locations; discharge monitoring locations; areas of particularly high risk for contaminant spills, such as fueling islands, vehicle or equipment washing areas, or loading docks; and locations of possible offsite discharges onto the property.

2)    Pollution Prevention Team: 
The team helps the site manager develop, review, and revise the SWPPP. The team is also tasked with insuring that Best Management Practices, or BMPs are in place and being adhered to. Finally, the names and positions of the team are maintained in the SWPPP and NPDES permit.

3)    Conditions and Actions that Can Cause Pollution:
The SWPPP must describe each outdoor area or activity that represents a pollution risk, such as uncovered, outdoor storage of raw materials, waste material, or industrial by-products. A three-year record of past spills must also be maintained.

Stockpiled soil, sand, road salt, or other materials, stored on hard surfaces and subject to rain or snowmelt, are one of the major causes of pollution entering storm drains. Vehicular fluids, stored equipment, and vehicle wash areas are also a significant source of water pollution. Leaks and spills during fueling and maintenance are another common way for oils, petroleum, and solvents to enter stormwater systems.

4)    Pollution Countermeasures and Controls:
Each potentially harmful process or area at a facility must be controlled with at least one countermeasure, as described in the SWPPP. The NPDES permit lists each potential pollutant at the facility, along with its effluent limit, or maximum allowed concentration as measured at a data collection point. However, the NPDES permit does not include a discussion of the applied countermeasures, which are detailed in the SWPPP. 

Countermeasures can incorporate simple, basic stormwater BMPs, such as keeping vehicles, soil, sand, salt, or stockpiled chemicals in an indoor or covered area, or can include more technologically involved stormwater BMPs such as stormwater catch basin filters, oil-water separators, settling tanks, or vegetated swales. Other stormwater BMPs can include periodic inspections of vehicles and equipment for fluid leaks, regular sweeping of parking and equipment storage areas, and the placement of filtration pads around vulnerable ditches or catch basins.

5)    Required Monitoring and Inspection Procedures:
The NPDES permit specifies the stormwater monitoring schedule, the types of pollutants to be analyzed along with their respective allowances, and often, the specific location and procedure for collecting stormwater samples for analysis. The Oregon Department of Environmental Quality (ODEQ), which regulates stormwater pollution in Oregon, requires quarterly Discharge Monitoring Reports (DMRs), and all facilities are required to report any non-compliance events. 

Facilities are also required to conduct routine inspections to verify that the selected controls and countermeasures are in fact working. By keeping a record of inspections, a facility can prove during a compliance audit that BMPs are in place and being followed.

6)    Spill Response Procedures:
Despite best intentions and diligent planning, spills of pollutants can and do occur even at the most well-managed facilities. Therefore each site much establish a Spill Response Plan (SRP). The SRP should be kept with the SWPPP to document spill response principles and procedures. Often the spill response plan for other regulatory requirements, such as fuel storage and product loading/unloading can qualify as the SWPPP SRP.

7)    Worker Training Program:
A facility is required to keep written records of its worker training program with regard to BMPs, SRPs, and the SWPPP. The training should be conducted in concert with other environmental training requirements, such as Hazardous Waste Operations and Emergency Response (HAZWOPER) training, which is required under the Occupational Safety and Health Administration (OSHA) standard 29 CFR Part 1910.120 for facilities that handle hazardous substances.

8)    Periodic SWPPP Review and Revision:
When a facility makes changes to the way it stores or handles potential stormwater contaminants, it is required to revise its SWPPP accordingly. Such changes can include moving a process or storage area to another location, streamlining a process to reduce contaminant use or exposure to stormwater, turnover of relevant personnel, or adding a new process or potential pollutant to the facility. The SWPPP should also be reviewed when the NPDES permit is being renewed. Plans must be signed and dated by the relevant corporate officer, and kept on site to document compliance. Ideally, the SWPPP should be part of the overall standard operating procedures (SOPs) at a facility, to insure that environmental protection and compliance are understood by all employees and integrated into day-to-day operations.


AAI serves all of Oregon and Washington, including Portland, Salem, Gresham, Medford, Roseburg, Eugene, Corvallis, Bend, Klamath Falls, the Oregon Coast, the Columbia Gorge, Pendleton, La Grande, Vancouver, Olympia, Tacoma, Seattle, Spokane, and Tri Cities.

The experience of the Environmental Professional is the most important factor in insuring that your redevelopment project is conducted in accordance with the Oregon Department of Environmental Quality’s 401 Water Quality Certification Program. Our staff have extensive experience in stormwater management.