City Council Meeting Date: January 21, 2020
To: Mayor and City Council
City Administrator
From: Justin Wagner, Utilities Manager
David Bennett, P.E., Public Works Director/City Engineer
Title
Update of City’s Wastewater Treatment Plant Draft National Pollutant Discharge Elimination System (NPDES)/ State Disposal System (SDS) Permit.
Body
Action Requested:
The Northfield City Council is asked to discuss the receipt of the City’s Wastewater Treatment Plant Draft NPDES/SDS Permit.
Summary Report:
On December 5, 2019, the City was sent a copy of its Pre-Public Notice Draft NPDES/SDS Permit for the City’s Wastewater Treatment Plant (WWTP). As part of the Pre-Public Notice Draft, the City is allowed 30 days to provide comments to the Minnesota Pollution Control Agency (MPCA) regarding the permit. Following the City’s Pre-Public Notice, the Draft Permit will be on public notice for 60 days. Following the public notice, the permit can be issued for a 5 year period.
The City’s WWTP operates based upon a NPDES permit that dictates the quality of treated wastewater that is allowed to enter the Cannon River. The NPDES permit is required in order to discharge into the Cannon River. In April of 2015, City staff completed a NPDES permit application to the Minnesota Pollution Control Agency. The City is currently operating on an extension of the existing permit.
Items incorporated within the draft NPDES/SDS permit include changes to phosphorous loading limits and adjustments to monitoring frequency for mercury. Additionally, staff is requesting clarification from the MPCA on changes to reporting requirements. Staff has provided comments to the MPCA which are included with the staff report as attachment 3.
Currently, the City is able to meet all of the requirements that are within the draft permit. With the changes to the phosphorous loading limits, staff anticipates that additional treatment requirements will be needed to meet the limits when the WWTP approaches its design flow. Currently, the WWTP has an average wet weather design of 5.2 million gallons per day. The current average flow is 2.5 million gallons per day. Within the draft permit, the City is required to submit a compliance evaluation report regarding phosphorous with the next permit application, which will be in 5 years.
Alternative Options:
Not Applicable
Financial Impacts:
Currently there are no financial impacts to the City but ultimately, if the permit limits are implemented, the City has the potential to be required to construct an additional treatment process in the future.
Tentative Timelines:
The City anticipates that the public notice will begin in January and take place for 60 days. Following the public notice, the permit will be issued and will be in effect for the next 5 years.