City News


Posted on: September 17, 2021

City of Mexico Proposed Pretreatment Program Modification

City of Mexico Proposed Pretreatment Program Modification Public Comment Period, Sept. 17, 2021 to Oct. 18, 2021

The City of Mexico currently has an approved pretreatment program to meet the requirements of the Clean Water Law.

Area of Focus: Water
Event Type: Public Notice/ Public Comment
Organization: Water Protection Forum

The City of Mexico currently has an approved pretreatment program to meet the requirements of the Clean Water Law. The City of Mexico submitted a proposed modification to that pretreatment program. The department reviewed the proposal and intends to approve the modification. The department invites the public to review and offer written comments on the proposed pretreatment program modification until Oct. 18, 2021. All comments must be received or postmarked by 5 p.m. The public can review the proposed permit conditions below. Other relevant information is available for review and copying upon request. 

Written comments may be submitted by mail to Missouri Department of Natural Resources, Water Protection Program, ATTN: Pretreatment Coordinator, PO Box 176, Jefferson City, MO 65102-0176 or by email to Please include the permit number in the comment letter. The department can only consider comments about issues relating to the proposed action. The department cannot consider comments or objections based on issues outside the authority of the Missouri Clean Water Commission. 

The City of Mexico modified its sewer user ordinance to include updated local limits after conducting a detailed reevaluation of local limit analysis that is part of this program modification. The City of Mexico Route J Wastewater Treatment Facility will establish maximum allowable industrial loadings (MAILs) for the 15 EPA National Pollutants of Concern (POCs), except arsenic. This ordinance change removes established maximum daily average concentration limits for previously established POCs and establishes monthly average limits MAILs (Section 40-218) to be allocated to permitted industrial users based on need for a specific POCs. For conventional POCs, revising the local limits establishes MAILs. Mexico also increased its total oil and grease (Hexane Extraction Method) prohibited discharge standard to 175 mg/L. Mexico’s ordinance also 1) clarified surcharge limits for conventional parameters (Section 40-160), 2) added authority to develop Best Management Practices, 3) clarified permitting process and 4) update penalties and fines (see Mexico’s cover letter). The city also updated its Enforcement Response Plan, which incorporates the 2005 EPA Streamlining Rule.

These changes could have a significant impact on the operation of the program, pursuant to 40 CFR 403.18(b)(7). The proposed department approval is tentative pending public comment. The modification request will be approved if no comments are received by the date specified in this notice; where no substantive comments are received, the notice of intent for approval is approved without change.

Proposed Pretreatment Program Modification MO0036242

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