Wastewater Pretreatment
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Pretreatment Responsibilities of POTWs
All publicly owned treatment works (POTWs) are responsible to control their Industrial Users (IUs) to prevent interference and pass-through.
POTWs that do not have formally delegated pretreatment programs must notify the MPCA of any Significant Industrial User (SIU) within 30 days of identifying the IU as significant.
The notification should be made using the form provided and must give identifying information on the POTW and the SIU, description of SIU, characterization of discharge from the SIU, required local limits imposed on the SIU, justification of these required local limits, and a plan for monitoring the SIU. Other information may also be requested by MPCA.
POTWs must control SIUs individually and must not impose limits on the SIU that the POTW knows may allow violations of the general or specific prohibitions.
The POTW generally should impose required local limits for all SIUs, and is specifically required to do so when interference or pass-through has occurred and may reoccur. A POTW also must evaluate or reevaluate the need for, and value of, local limits if intereference or pass-through occurs without a violation of a required local limit by an SIU.
The POTW must monitor SIUs for pollutants of concern, or require the SIU to self monitor. Monitoring must be representative of the SIU discharge.
The POTW must report annually on the pretreatment annual report form provided. We plan to send out forms annually to POTWs that we know have SIUs. The SIUs known to MPCA will be listed on the forms. Copies of the annual report forms are available below. The annual report form comes in four parts:
Wastewater Pretreatment Annual Report - SIU Information Form
- Monitoring of Significant Industrial User Form
- SIU Monitoring Parameters and Units List
When we mail the forms to you we will include your known SIUs one the SIU Information Form.
Delegated POTWs have additional and more detailed responsibilities. A delegated POTW Pretreatment program requires substantial program development and a formal delegation process. There are currently nine delegated POTWs in Minnesota.
Responsibility To Enforce Pretreatment Standards
All POTWs are responsible to control IUs to prevent interference and pass-through, and to control SIUs as described above.
Delegated POTWs are also responsible to enforce national categorical pretreatment standards for IUs in their systems. Elsewhere MPCA enforces national categorical pretreatment standards through the use of MPCA issued permits.
POTWs should notify the MPCA if they believe that they have IUs subject to national categorical pretreatment standards.
Forms
- Pretreatment Notification of a Significant Industrial User. This form is to be submitted by a POTW when the POTW identifies a Significant Industrial User (SIU).
- Wastewater Pretreatment Annual Report - This is the main form for a pretreatment annual report, which must be submitted by any POTW that has an SIU during the reporting year.
- SIU Information Form - This form lists the POTW’s SIUs and is used to provide information regarding the SIU during the reporting year.
- Monitoring of Significant Industrial User Form - This form is used to summarize monitoring of SIUs for the reporting year.
- SIU Monitoring Parameters and Units List - This list indicates the parameters and units we request that POTWs use in reporting monitoring data on the Monitoring of SIU form.
MPCA Staff Contact
For assistance with pretreatment standards and requirements, contact:
Aaron Luckstein
MPCA Rochester office
18 Wood Lake Drive SE
Rochester, MN 55904
Phone: 507-206-2606
Fax: 507-280-5513
aaron.luckstein@state.mn.us
Glossary
IU or Industrial User is a non-domestic user of the POTW. An IU is inherently identified with a specific POTW.
Interference occurs when the POTW has a violation of its limits that is caused by an IU discharge that upsets the POTW plant and causes the violation. The pollutant limit violated can be any limited pollutant in the POTWs discharge or biosolids, but interference does require a showing of some kind of negative impact on the operation of the POTW.
National Categorical Pretreatment Standards are federal technology based standards that apply to specific categories of industrial users. They can be found in the Code of Federal Regulations, 40 CFR 405 through 40 CFR 471.
Pass-Through occurs when the POTW has a violation of its limits caused by an IU discharge that passes through the POTW plant without being adequately treated. The pollutant limit violated must be a pollutant discharged by the IU, but no showing of any impact on POTW operation is needed.
SIU or Significant Industrial User is first of all an IU that has potential to impact the POTW. Additional criteria that identify an IU as an SIU are: the IU discharges 5% or more of flow or load to the POTW of any pollutant of concern, or the IU discharges 25,000 gallons per day of process wastewater.
Required Local Limits are limits imposed by a POTW on its IUs or SIUs that are needed to prevent interference or pass-through, as required by pretreatment rules and regulations. In addition to these required local limits, a POTW may have other local limits, that are not required by pretreatment rules and regulations. Required local limits are enforcable by MPCA, pretreatment local limits that are not required by pretreatment rules and regulations are not enforceable by MPCA.
