The Wastewater Department is charged with making sure that harmful substances aren't discharged into our sewer system. Our Industrial Pretreatment Program is set up to talk to businesses and identify things that can be problem.
The City has a Pretreatment Ordinance that allows us to condition or deny businesses from discharging some substances into the sanitary sewer—substances that create safety hazards, damage structures, interfere with treatment plant operations and processes, or that can't be removed and pass through into biosolids or with the effluent into the Spokane River.
The Pretreatment Program's first step is to survey businesses to determine whether they have the potential to discharge anything other than domestic wastewater. The information gathered by the survey is used to determine what the business has to do and informs us about what is in the wastewater system. We can also help businesses to avoid any accidental spills. The information is also reported annually to the Washington State Department of Ecology.
Business owners should understand the regulations that apply to their wastewater discharge, and comply with applicable regulations and standards. Let's take a look at what's required.
Businesses that discharge wastewater only from restrooms or hand sinks are considered Domestic Dischargers. They are responsible for ensuring that no Prohibited Discharges are introduced to the sewer system from their facility. This level of normal domestic use is not regulated.
Businesses that discharge wastewater containing nondomestic pollutants must abide by local limits and follow industry-specific Best Management Practices (BMPs) to keep their wastewater as clean as reasonably possible.
BMPs can prevent the release of pollutants that can damage the sewers or the treatment plant, cause the plant to release pollutants that violate its Permit, or endanger wastewater personnel.
For example, restaurants that do not properly maintain their grease interceptors can cause grease clogs in the sewer resulting in sewer backups into streets or basements; auto repair shops that do not properly dispose of used solvents can cause an explosion hazard in the sewer or at the plant headworks; and car wash operations that use acidic cleaners and do not properly neutralize their wastewater prior to discharge can cause acid damage to the sewers.
The City of Spokane requires all Significant Industrial Users to obtain a Wastewater Discharge Permit.
A Significant Industrial User is:
Pretreatment program staff scientists inspect such permitted businesses, sample their wastewater discharges, and work with them to protect the environment, the wastewater treatment plant, and personnel.
Any industry that discharges wastewater directly to a river or other surface water (Direct Dischargers) must apply for and comply with a Discharge Permit from the Washington State Department of Ecology.
Fats, Oils, and Grease (FOG) are a particular problem for our wastewater system. Oily, greasy waste, often from restaurants and commercial kitchesns, that gets into a sink or drain that goes into the sewer can build up and cause sewer blockages. In fact, FOG is the number one cause of such blockages, as it solidifies on the walls of sewer pipe.
Simple ways of reducing the amount of FOG going down your drains include:
Every food preparation establishment is required to have a grease trap or interceptor. There are three types: passive grease traps that are usually located under the sink and must be cleaned out by hand; automatic grease traps that continually skim grease off and deposit it in a removable reservoir; and grease interceptors that are large volume devices, usually located outside, under the ground and must be pumped out by a grease hauler.
These devices are very important but they can't do the job alone: