Industrial Pretreatment

 General Requirements

All commercial and industrial users of the Lake Stevens Sewer District (LSSD)’s Wastewater Treatment Plant must comply with the pre-treatment regulations described in 40 CFR Part 403 and any additional regulations that the Environmental Protection Agency (U.S. EPA) may promulgate under Section 307(b) (pre-treatment) and 308 (reporting) of the Federal Clean Water Act.


Significant Industrial User:  a discharger of non-domestic wastewater that contributes an average of 25,000 gallons per day or more to the Publicly Owned Treatment Works (POTW) or contributes a waste stream which makes up 5 percent or more of the average dry weather hydraulic or organic capacity of the POTW.

Duty to Enforce Discharge Prohibitions

Under federal regulations (40 CFR 403.5(a) and (b)), LSSD must not authorize or knowingly allow the discharge of any pollutants into its POTW which may be reasonably expected to cause pass through or interference, or which otherwise violate general or specific discharge prohibitions contained in 40 CFR Part 403.5 or WAC 173-216-060.

LSSD must not authorize or knowingly allow the introduction of any of the following into their treatment works: 

  1.  Pollutants which create a fire or explosion hazard in the POTW (including, but not limited to waste streams with a closed cup flashpoint of less than 140 degrees Fahrenheit or 60 degrees Centigrade using the test methods specified in 40 CFR 261.21).
  2.  Pollutants which will cause corrosive structural damage to the POTW, but in no case discharges with pH lower than 5.0, or greater than 11.
  3.  Solid or viscous pollutants in amounts that could cause obstruction to the flow in sewers or otherwise interfere with the operation of the POTW.
  4.  Any pollutant, including oxygen-demanding pollutants, (BOD, etc.) released in a discharge at a flow rate and/or pollutant concentration which will cause interference with the POTW.
  5.  Petroleum oil, non-biodegradable cutting oil, or products of mineral origin in amounts that will cause interference or pass through.
  6.  Pollutants which result in the presence of toxic gases, vapors, or fumes within the POTW in a quantity which may cause acute worker health and safety problems.
  7.  Heat in amounts that will inhibit biological activity in the POTW resulting in interference but in no case heat in such quantities such that the temperature at the POTW headworks exceeds 40 degrees Centigrade (104 degrees Fahrenheit).
  8.  Any trucked or hauled pollutants.
  9.  Wastewaters prohibited to be discharged to the POTW by the Dangerous Waste Regulations (chapter 173-303 WAC), unless authorized under the Domestic Sewage Exclusion (WAC 173-303-071).

Wastewater Discharge Permit Required

  1.  All Significant Industrial Users (SIU’s) in the sewer system must meet applicable State Waste Discharge Permit (SWDP) requirements in accordance with chapter 90.48 RCW and chapter 173-216 WAC.
  2.  All SIU’s must immediately notify LSSD of any proposed discharge
  3.  All SIU’s must obtain a SWDP from the Washington State Department of Ecology (Ecology) prior to discharging their non-domestic wastewater or prove that Ecology has determined that they do not require a permit.
  4.  Documentation described in #3 is required at the earliest practicable date as a condition of continuing to accept non-domestic wastewater discharges  from a previously undiscovered, currently discharging and unpermitted SIU.
  5.  Sources of non-domestic wastewater which do not qualify as SIU’s but merit a degree of oversight must apply for a SWDP and provide a copy of the application along with any responses from Ecology.

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