National Pollutant Discharge Elimination System /State Disposal System (NPDES/SDS) Permit Program Fact
Sheet
Permittee: City of Buffalo
Facility Name: Buffalo WWTF
Permit Number: MN0040649
212 Central Avenue
One 25th Street SE
Buffalo, MN 55313
Buffalo, MN 55313
Current Permit Expiration: November 30, 2012
Public Comment Period Begins: October 9, 2012
Period Ends: November 8, 2012
Receiving Water: North Fork of the Crow River (Class 2B, 3C, 4A, 4B, 5,
6 Water)
Proposed Action: Permit Reissuance
Permitting Contact
Holly Christensen
Minnesota Pollution Control Agency
714 Lake Avenue, Suite 220
Detroit Lakes, MN 56501
Phone 218-846-8104
Fax 218-846-0719
1
Table of Contents Purpose and Participation ................................................................................................................. 3‐4 Applicable Statutes ............................................................................................................... 3 Purpose ................................................................................................................................. 3 Public Participation ............................................................................................................... 3‐4 Facility Description............................................................................................................................. 4‐7 Background Information ....................................................................................................... 4‐5 Facility Location ....................................................................................................... 4 Outfall Location ....................................................................................................... 4 Map of Permitted Facility ........................................................................................ 5 Components and Treatment Technology ............................................................................. 6‐7 Current Information................................................................................................. 6 Changes to Facility or Operation ............................................................................. 6
Significant Industrial Users ...................................................................................... 6 Recent Compliance History ...................................................................................... 6 Table 1. Recent Monitoring History .................................................................... 7 Receiving Water(s) ............................................................................................................................. 8‐9 Use Classification .................................................................................................................. 8 Impairments, Listings, and Total Maximum Daily Load Studies ........................................... 8‐9 Table 2. Impairments for the Receiving Water ................................................................ 8 Existing Permit Effluent Limits ........................................................................................................... 10‐11 Technology Based Effluent Limits ......................................................................................... 10 Water Quality Based Effluent Limits ..................................................................................... 10 State Discharge Restriction Limits ........................................................................................ 10 Table 3. Existing Effluent Limits and Monitoring Requirements ...................................... 10‐11 Proposed Permit Effluent Limits ........................................................................................................ 12‐13 Technology Based Effluent Limits ......................................................................................... 13 Water Quality Based Effluent Limits ..................................................................................... 13 State Discharge Restriction Limits ........................................................................................ 13 Table 4. Proposed Effluent Limits and Monitoring Requirements ................................... 12‐13 Background ........................................................................................................................... 13 Reasonable Potential for Chemical Specific Pollutants ........................................................ 14‐16 Table 5. Reasonable Potential Analyses ........................................................................... 15 Table 6. Applicable EPA Methods .................................................................................... 16 Reasonable Potential for Chronic Whole Effluent Toxicity .............................................. 16 Priority Pollutants ............................................................................................................. 16 Additional Requirements ................................................................................................................... 17 Mercury Minimization Plan .................................................................................................. 17 Additional Monitoring Requirements ................................................................................... 17 Biosolids ................................................................................................................................ 17 Compliance Schedules .......................................................................................................... 17 Variances............................................................................................................................... 17 Total Facility Requirements ............................................................................................................... 17 Nondegredation and Anti‐backsliding ............................................................................................... 17‐18 2
Purpose and Participation Applicable Statutes This fact sheet has been prepared according to the Title 40 Federal Code of Regulations (CFR) 124.8 and 124.56 and Minn R. 7001.0100, Subp. 3 in regards to a draft NPDES/SDS permit to construct and/or operate wastewater treatment facilities and to discharge into waters of the State of Minnesota. Purpose This fact sheet outlines the principal issues related to the preparation of this draft permit and documents the decisions that were made in the determination of the effluent limitations and conditions of this permit. Public Participation You may submit written comments on the terms of the draft permit or on the Commissioner’s preliminary determination. Your written comments must include the following: 1. A statement of your interest in the permit application or the draft permit. 2. A statement of the action you wish the Minnesota Pollution Control Agency (MPCA) to take, including specific references to sections of the draft permit that you believe should be changed. 3. The reasons supporting your position, stated with sufficient specificity as to allow the Commissioner to investigate the merits of your position. You may also request that the MPCA Commissioner hold a public informational meeting. A public informational meeting is an informal meeting which the MPCA may hold to help clarify and resolve issues. In accordance with Minn. R. 7000.0650 and Minn. R. 7001.0110, your petition requesting a public informational meeting must identify the matter of concern and must include the following: items 1 through 3 identified above; a statement of the reasons the MPCA should hold the meeting; and the issues you would like the MPCA to address at the meeting. In addition, you may submit a petition for a contested case hearing. A contested case hearing is a formal hearing before an administrative law judge. Your petition requesting a contested case hearing must include a statement of reasons or proposed findings supporting the MPCA decision to hold a contested case hearing pursuant to the criteria identified in Minn. R. 7000.1900, subp. 1 and a statement of the issues proposed to be addressed by a contested case hearing and the specific relief requested. To the extent known, your petition should include a proposed list of witnesses to be presented at the hearing, a proposed list of publications, references or studies to be introduced at the hearing, and an estimate of time required for you to present the matter at hearing. You must submit all comments, requests, and petitions during the public comment period identified on page 1 of this notice. All written comments, requests, and petitions received during the public comment period will be considered in the final decisions regarding the permit. If the MPCA does not receive any written comments, requests, or petitions during the public comment period, the Commissioner or other MPCA staff as authorized by the Commissioner will make the final decision concerning the draft permit. During the public comment period, however, you may request that the draft permit be presented to the MPCA’s Citizens’ Board (Board) for final decision. You may participate in the activities of the Board as provided in Minn. R. 7000.0650. Comments, petitions, and/or requests must be submitted by the last day of the public comment period to: 3
Holly Christensen Minnesota Pollution Control Agency 714 Lake Avenue, Suite 220 Detroit Lakes, MN 56501 The permit will be reissued if the MPCA determines that the proposed Permittee will, with respect to the facility or activity to be permitted, comply or undertake a schedule to achieve compliance with all applicable state and federal pollution control statutes and rules administered by the MPCA and the conditions of the permit and that all applicable requirements of Minn. Stat. ch. 116D and the rules promulgated thereunder have been fulfilled. More detail on all requirements placed on the facility may be found in the Permit document. Facility Description Background Information Facility Location The Buffalo Wastewater Treatment Facility (Facility) is located in the NE ¼ of Section 13, Township 119 North, Range 26 West, Marysville Township, Wright County, Minnesota, approximately three miles south of Buffalo, Minnesota. Outfall Location The outfall pipe (Station SD001) for the Facility is located in the SE ¼ of Section 13, Township 119 North, Range 26 West, Marysville Township, Wright County, Minnesota, about 1/3 of a mile south of the Facility. 4
Map of Permitted Facility 5
Components and Treatment Technology Current Information The existing Facility consists of a collection system with gravity and/or pressure sewer, 2 fine screens, 1 mechanical bar screen, grit removal, 2 oxidation ditches (activated sludge units/extended aeration), biological and chemical (ferric chloride) phosphorus removal, 3 final clarifiers, ultraviolet disinfection, and 2 Effluent Equalization Structures (cascade aeration). The biosolids treatment components include: 6 Aerobic Digesters, 1 500,000 gallon biosolids storage tank, 2 belt filter presses, heat drying, 1 furnace incinerator, and an ash and dried biosolids handling system. The existing Facility is designed to treat an annual average wet weather flow (AWWF) of 4,320,000 gallons per day (gpd) with a carbonaceous biochemical oxygen demand strength of 158 milligrams per liter (mg/l). The Facility is designed to treat an average dry weather flow of 2,340,000 gpd, an average annual flow of 2,880,000 gpd, a peak hourly wet weather flow of 8,000,000 gpd, and a peak instantaneous wet weather flow of 8,600,000 gpd. The Facility has a continuous discharge (Station SD001) to the North Fork of the Crow River (Class 2B, 3B, 4A, 4B, 5, 6 Water). A drain tile has been installed at this Facility to collect groundwater under the tanks and has the ability to discharge at Station GW001 to a holding pond located on‐site. There are no bypass or overflow points known to exist at this Facility. The MPCA has evaluated the treatment components of the Facility with regards to the mass limits in the permit. At the time of permit issuance, the Facility is operating at less than the permitted design AWWF rate of 4,320,000 gpd and is demonstrating the capability of meeting the effluent mass limit of 4,775 kilograms per year for total phosphorus. As the Facility approaches its AWWF, it may need infrastructure improvements and/or operational changes to maintain compliance with the mass limits. The Facility can be further described in plans and specifications and addenda, dated November 21, 2006 and April 30, 2007, respectively, completed by the firm of Bolton & Menk, Inc., and kept on file at the Minnesota Pollution Control Agency, St. Paul. Changes to Facility or Operation There are no planned changes for the existing Facility during this 5‐year permit cycle. Significant Industrial Users (SIUs) There are no known SIUs that discharge to this Facility. Recent Compliance History The most recent inspection by MPCA staff occurred on June 7, 2010, and included the review period of May 1, 2008 through June 1, 2010. Based on the results of the inspection, there was one violation of permit conditions – one discharge monitoring report was submitted late. Overall the Facility is in good condition with operations running at about half of the design flow. There were no enforcement actions during this review period, nor have there been any since. See Table 1 for the 2011 calendar year sampling and monitoring results. 6
Table 1. Recent Monitoring History 7
Receiving Water Use Classification The receiving water (North Fork of the Crow River) is a Class 2B, 3C, 4A, 4B, 5, and 6 Water. 7050.0200 Water Use Classifications For Waters Of The State Subp. 3. Class 2 waters, aquatic life and recreation. Aquatic life and recreation includes all waters of the state which do or may support fish, other aquatic life, bathing boating or other recreational purposes, and where quality control is or may be necessary to protect aquatic or terrestrial life or their habitats, or the public health, safety, or welfare. Subp. 4. Class 3 waters, industrial consumption. Industrial consumption includes all waters of the state which are or may be used as a source of supply for industrial process or cooling water, or any other industrial or commercial purposes, and for which quality control is or may be necessary to protect the public health, safety, or welfare. Subp. 5. Class 4 waters, agriculture and wildlife. Agriculture and wildlife includes all waters of the state which are or may be used for any agriculture purposes, including stock watering and irrigation, or by waterfowl or other wildlife, and for which quality control is or may be necessary to protect terrestrial life and its habitat or the public health, safety, or welfare. Subp. 6. Class 5 waters, aesthetic enjoyment and navigation. Aesthetic enjoyment and navigation includes all waters of the state which are or may be used for any form of water transportation or navigation, or fire prevention, and for which quality control is or may be necessary to protect the public health, safety, or welfare. Subp. 7. Class 6 waters, other uses. Other uses includes all waters of the state which are or may serve the above listed uses or any other beneficial uses not listed herein, including without limitation any such uses in this or any other state, province, or nation of any waters flowing through or originating in this state, and for which quality control is or may be necessary for the above declared purposes, or to conform with the requirements of the legally constituted state or national agencies having jurisdiction over such waters, or any other considerations the agency may deem proper. There are no endangered or threatened species living in the receiving water. Impairments, Listings, and Total Maximum Daily Load Studies Table 2. Impairments for the Receiving Water AUID or Lake ID#
07010204-503
AUID Description
North Fork of the Crow River:
Mill Creek to the South Fork
of the Crow River
Assessment Category
5B
Impairment or Pollutants
Mercury in Fish Tissue,
Dissolved Oxygen, and
Turbidity
Total Maximum Daily Load Studies: Statewide TMDL: Mercury Pollutant Reduction Plan, approved March 27, 2007 Lake Pepin TMDL: Excess Nutrients (not completed yet) South Metro Mississippi River TSS TMDL – came off public notice May 29, 2012 (not completed yet) North Fork Lower Crow River TMDL – Bacteria, Turbidity, and Dissolved Oxygen/2012, public notice period extended until September 4, 2012 (not completed yet) 8
Statewide TMDL: Mercury Pollutant Reduction Plan – According to the “Permitting Strategy for Addressing Mercury in Municipal and Industrial Wastewater Permits” (which is part of the TMDL’s Implementation Plan), existing major facilities with no reasonable potential to exceed the water quality standard for mercury (Buffalo falls into this category) are required to monitor Total Mercury and, additionally, Dissolved Mercury and TSS (grab) in their effluent twice per year. For facilities outside the Lake Superior Basin (Buffalo also falls into this category), they are also required to complete a Mercury Minimization Plan (MMP).The draft permit includes each of these requirements and is therefore consistent with this TMDL. Lake Pepin TMDL Study – This Facility discharges treated effluent to the North Fork of the Crow River upstream of Lake Pepin, a reservoir on the Mississippi River. In 2002, Lake Pepin was placed on the federal Clean Water Act Section 303(d) list of impaired waters due to excess nutrients. A TMDL study is currently being developed and a significant portion of the modeling analysis has been completed. Phosphorus is the primary nutrient responsible for excess algal growth in Lake Pepin. Federal law [40 CFR 122.44(d)] restricts mass increases upstream of impaired waters and states that all NPDES dischargers that have the reasonable potential (RP) to cause or contribute to downstream impaired waters are required to have a water quality based effluent limit (WQBEL). When determining RP, the Code of Federal Regulations also states that the MPCA shall use procedures which account for existing controls on point and nonpoint sources of pollution. Permittees are found to have RP for Total Phosphorus (TP) if: 1) they discharge upstream of a nutrient impaired waterbody, 2) they discharge at TP concentrations greater than the ambient target, and 3) there is no geographical barrier capable of trapping a significant mass of nutrients between the outfall and the impairment. For all reasons listed above, the Facility is found to have RP for TP upstream of Lake Pepin. Therefore, the Facility is required to have a TP WQBEL. It is recommended that the Facility receive a 4,775 kilograms per year (kg/yr) TP WQBEL which was derived from a draft TMDL wasteload allocation (WLA) which in turn is derived from the water quality standard that the receiving water must meet to support designated uses. More restrictive TP limits may be necessary following the completion of the Lake Pepin TMDL study and the adoption of numeric river nutrient criteria during the next triennial rulemaking session. South Metro Mississippi River Total Suspended Solids (TSS) Total Maximum Daily Load (TMDL) Study To address water quality impairments in the South Metro Mississippi River, of which is the North Fork of the Crow River is part of, the South Metro Mississippi River TSS TMDL has been written and came off of public notice on May 29, 2012. The TMDL contains the following WLAs for TSS: 149,285 kg/year and 409.0 kg/day. These limitations are the results of calculations based on the permit’s current permit limits of 30 mg/l as a calendar month average and 45 mg/l as a maximum calendar week average. Therefore; the TSS limits included in this permit are consistent with the draft TMDL’s WLAs. North Fork Lower Crow River TMDL: Bacteria, Turbidity, and Dissolved Oxygen A. According to this draft TMDL, the E. coli allocation for the Buffalo Facility is 126 organisms/100 ml. The draft TMDL states that NPDES wastewater permit limits are currently expressed in fecal coliform concentrations, not E. coli. However, the fecal coliform permit limit for each wastewater treatment facility (200 organisms/100 ml) is equivalent to this TMDL’s 126 organisms/100 ml E. coli criterion. B. According to this draft TMDL, the TSS allocation is 0.451 tons per day. This allocation is equivalent to the current TSS limit of 30 mg/l and is therefore consistent with the TMDL. C. According to this draft TMDL, there are no WLAs for this facility for Dissolved Oxygen. 9
Existing Permit Effluent Limits The limits and monitoring requirements in the current Permit are presented in Table 3 and list water quality based effluent limits, technology based effluent limits, and state discharge restriction limits. Technology Based Effluent Limits (TBELs) The Total Suspended Solids and pH limits are technology based limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR §133.102 and Minn. R. 7050.0211 and Minn. R. 7053.0215. Water Quality Based Effluent Limits (WQBELs) The 5‐day Carbonaceous Biochemical Oxygen Demand, Total Ammonia Nitrogen, Total Copper, and Dissolved Oxygen limits are water quality based effluent limits. The different Dissolved Oxygen limits were assigned to ensure that the water quality standard for Dissolved Oxygen is protected during varying seasons of low flow. State Discharge Restriction Limits (SDRs) The Fecal Coliform and Total Phosphorus limits are State Discharge Restriction limits. These limits are specified in Minn. R. 7053.0215, Subp. 1 and Minn. R. 7053.0255 Subp. 3. Table 3. Existing Effluent Limits and Monitoring Requirements 10
11
Proposed Permit Effluent Limits The limits and monitoring requirements in the proposed Permit are presented in Table 4 and list water quality based effluent limits, technology based effluent limits, and state discharge restriction limits. Technology Based Effluent Limits (TBELs) The pH limits are technology based limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR §133.102 and Minn. R. 7050.0211 and Minn. R. 7053.0215. Water Quality Based Effluent Limits (WQBELs) The Total Suspended Solids, 5‐day Carbonaceous Biochemical Oxygen Demand, Total Ammonia Nitrogen, Total Copper, Total Phosphorus, and Dissolved Oxygen limits are water quality based effluent limits. The different Dissolved Oxygen limits were assigned to ensure that the water quality standard for Dissolved Oxygen is protected during varying seasons of low flow. State Discharge Restriction Limits (SDRs) The Fecal Coliform limit is a State Discharge Restriction limit. This limit is specified in Minn. R. 7053.0215, Subp. 1 and Minn. R. 7053.0255 Subp. 3. Table 4. Proposed Effluent Limits and Monitoring Requirements 12
Background The discharge is located on the North Fork of the Crow River. The Permittee has submitted 6 Whole Effluent Toxicity (WET) tests, one repeat WET test and 3 priority pollutant scans since 2008. The Average Dry Weather (ADW) design flow is used to calculate water quality‐based effluent limits under critical low flow stream conditions. The ADW for this facility is 2.34 million gallons per day (mgd). The low flow condition is defined by the once in ten year weekly average flow (7Q10), which is determined to be 12.605 mgd or 19.50 cfs .The dilution ratio is 5.38:1, river low flow to effluent flow at the ADW. The analysis below is based on data submitted to date. 13
Reasonable Potential for Chemical Specific Pollutants (40CFR122.44(d)(1)) Federal regulations require MPCA to evaluate the discharge to determine whether the discharge has the reasonable potential to cause or contribute to a violation of water quality standards. The Agency must use acceptable technical procedures, accounting for variability (coefficient of variation, or CV), when determining whether the effluent causes, has the reasonable potential to cause, or contribute to an excursion of an applicable water quality standard. Projected effluent quality (PEQ) derived from effluent monitoring data is compared to Preliminary Effluent Limits (PELs) determined from mass balance inputs. Both determinations account for effluent variability. Where PEQ exceeds the PEL, there is reasonable potential to cause or contribute to a water quality standards excursion. When reasonable potential is indicated the permit must contain a water quality‐based effluent limit (WQBEL) for that pollutant. The priority pollutant scan information of the effluent was evaluated using reasonable potential procedures. All of the organic priority pollutants were below the level of detection. Since these pollutants were at low enough levels not to be detected, reasonable potential to cause or contribute to a water quality standards excursion is not indicated. Total Copper, Total Zinc and Total Nickel were at detectable levels in the priority pollutant scans. In addition, Total Copper and Total Mercury were also routinely monitored as a part of the permit conditions. Table 5 below contains the inputs to the reasonable potential analysis for the total metals of copper, nickel, zinc, mercury, and chronic WET testing. The analysis is made with effluent data that is expressed as total metal. These pollutants were evaluated on the basis of analytical measurements that made evident the need for a full determination. Where PEQs exceed the PELs, a WQBEL is needed. The Table shows that Total Zinc, Total Nickel and Total Mercury indicated no reasonable potential to cause or contribute to an excursion above the applicable water quality standard. No effluent limits are needed for Total Zinc, Total Nickel, and Total Mercury (all total metals). However, reasonable potential to cause or contribute to an excursion above the applicable water quality standard was shown for Total Copper. Total Mercury‐ Monitoring results of the effluent include 17 data points at a calculated CV of 0.6. PEQ is derived as an upper bound value from the highest value measured (8.57 ng/l), and the determined variability (CV = 0.6) and number of data points (17). The PEL calculation assumes that the background Total Mercury concentration is at the water quality standard (6.9 ng/l) when the listed stream impairment is for fish consumption advice, and no local river water column analytical data exist. To assure that the discharge does not cause or contribute to a water quality standards excursion for mercury impaired waters, the numeric water quality standard (6.9 ng/l) is applied at the point of discharge for the mass balance equation for the subsequent preliminary effluent limit calculations. Where PEQ exceeds the PEL, there is reasonable potential to cause or contribute to a water quality standards excursion. Since PEQ does not exceed the PEL in this case, reasonable potential to cause or contribute to an excursion above water quality standards is not indicated. A WQBEL is not needed. Environmental Analysis and Outcomes (EAO) staff recommend following the Permitting Strategy for Mercury and having this facility monitor 2X/year for Total Mercury. 14
Table 5. Reasonable Potential Analyses Cu Zn Parameter (ug/L) Ni (ug/L) (ug/L) Hg (ng/L) WET(TUc) Max Measured Value 160 36
26
8.57
1.24
# data points 11 3
3
17
5
PEQ 288 108
78
11.998
2.852
Plant flow ADW (mgd) 2.34 2.34
2.34
2.34
2.34
Rec. water flow, 7Q10(mgd) 12.605 12.605042
12.605
12.605 12.605042
Background Conc. 0.8 1.2
1.5
6.9
0
Continuous Std (cs) 18.61 376.73
253.63
6.90
1.00
280 ppm hard Maximum Std (ms) 46.76 3388.80
279.99
2400.00
1.00
280 ppm hard Final Acute Value (FAV) 123 8658
716
4900
NA
374 ppm hard Mass Balance ‐cs 114.53 2399.63 1611.77
6.90
6.39
Mass Balance ‐ms 294.36 21637.04 1780.16 15291.08
6.39
Coeff of Variation (CV) 0.71 0.60
0.60
0.60
0.60
Long Term Avg‐cs 54.57 1265.63
850.08
5.38
NA
Long Term Avg‐ms 81.75 6947.55
571.60
4909.90
2.05
Preliminary Effl limits: Daily Max 196.51 3941.59 1780.16
16.77
6.39
Monthly Ave (2x/month) 106.33 2275.19 1027.56
9.68
NA
Reasonable Potential PEQ>Daily max TRUE FALSE FALSE FALSE FALSE PEQ> FAV TRUE FALSE FALSE FALSE FALSE Final Reasonable Potential Yes No No No No notes: background concentrations from 2007 reasonable potential review mercury background set to chronic std because of the statewide TMDL June 2009 WET test removed from data set because of retest 15
Reasonable Potential Conclusions for Total Copper Reasonable potential to cause or contribute to the excursion above a water quality standard has been indicated for Total Copper. For Total Copper, EAO staff recommends the following limits: 197 ug/l as a daily maximum and 106 ug/l as a monthly average (based on sampling 2X/month). Table 6. Applicable EPA Methods: EPA Inorganic Analytical Methods (EPA 600/4‐79‐020) and EPA Organic Analytical Methods (40 CFR 136; Oct. 26, 1984) Pollutant Monitoring Frequency EPA Method Method Detection Level Total daily 220.2 1 ug/l copper Total 2X/yr 1631 0.5 ng/l mercury Total Zinc and Total Nickel Recommendations EAO staff recommends no additional monitoring for either Total Nickel or Total Zinc. These will be part of priority pollutant scans. Reasonable Potential for Chronic Whole Effluent Toxicity (WET) The Permittee has chronic Whole Effluent Toxicity (WET) monitoring as a current requirement. The Permittee has chronic WET testing because the ratio of the 7Q10 low flow of the receiving water compared to the facility’s average Dry Weather Flow is less than or equal to 20:1. The monitoring threshold value of 4.4 Toxic Unit chronic (TUc) has been updated to 6.4 TUc because of updated information on updated 7Q10 receiving water flow. A reasonable potential evaluation was done on the chronic WET tests to determine if there was cause to exceed the WET monitoring threshold value of 6.4 TUc (6.39 TUc rounded). From 2008 to the spring of 2012, the facility ran six WET tests and one repeat test. One of the original tests, June 2009, was removed from the data set since there was a repeat test that immediately followed. The repeat test showed no toxicity. The repeat test was used as part of the data set for the reasonable potential evaluation for the chronic WET test to determine if a chronic WET limit is needed. No reasonable potential was found to exceed the monitoring threshold of 6.4 TUc. Because no reasonable potential has been found, a monitoring threshold value of 6.4 TUc has been established. The 6.4 TUc is a monitoring threshold value, not a WET limit. The following monitoring will be included: annual WET testing will be completed done once per year. If the permit exceeded five years, there will be an additional WET test for each year that exceeds the five year permit cycle. If the monitoring threshold value of 6.4 TUc is exceeded for any one WET test, the facility will perform two WET retests to determine if a Toxicity Reduction Evaluation (TRE) is needed. Priority Pollutants The Permittee is required to complete and submit three rounds of priority pollutant monitoring on the effluent during this five year permit cycle. Sampling events must be completed at least one year apart. 16
Additional Requirements Mercury Minimization Plans This permit contains requirements for mercury monitoring and for submittal of a Mercury Minimization Plan (MMP) or updated MMP. These requirements were added in response to the U.S. Environmental Protection Agency’s approval of the Minnesota state‐wide Mercury Total Maximum Daily Load Study. Additional Monitoring Requirements The draft permit requires additional monitoring for Nitrite plus Nitrate‐Nitrogen, Total Dissolved Solids, and Total Kjeldahl Nitrogen, at a frequency of two times per year for the five‐year term of the permit. These additional parameters are being added to every permitted municipal facility with an average wet weather design flow of 100,000 gallons per day or greater. Biosolids The draft permit authorizes the Permittee to store and land apply domestic wastewater treatment biosolids in accordance with the provisions in Chapter 9 of this draft permit and Minn. R., ch. 7041. Compliance Schedules The draft permit contains a compliance schedule for the Permittee to submit the as‐built plans and specifications for the completed upgrade that initiated operation on November 16, 2009. These were due to be submitted during the previous permit cycle but were never received by the MPCA. Variances There are no variances to water quality standards in the draft permit. Total Facility Requirements (TFR) All NPDES permits issued in the State of Minnesota contain certain conditions that remain the same regardless of the size, location, or type of discharge. The standard conditions satisfy the requirements outlined in 40 CFR 122.41. These conditions are listed in the Total Facility Requirements chapter of an NPDES permit. These requirements cover a wide range of areas including recordkeeping, sampling, equipment calibration, equipment maintenance, reporting, facility upsets, bypass, solids handling, changes in operation, facility inspections, and permit reissuance. Nondegredation and Anti‐Backsliding In accordance with MPCA rules regarding nondegradation for all waters that are not Outstanding Resource Value Waters, nondegradation review is required for any new or expanded significant discharge (Minn. R. 7050.0185). A significant discharge is 1) a new discharge (not in existence before January 1, 1988) that is greater than 200,000 gallons per day to any water other than a Class 7 water or 2) an expanded discharge that expands by greater than 200,000 gallons per day that discharges to any water other than a Class 7 water or 3) a new or expanded discharge containing any toxic pollutant at a mass loading rate likely to increase the concentration of the toxicant in the receiving water by greater than one percent over the baseline quality. The flow rate used to determine significance is the design average wet weather flow. The January 1, 1988, design average wet weather flow for this facility is 1,400,000 gpd. This Permit also complies with Minn. R. 7053.0275 regarding anti‐backsliding. Any point source discharger of sewage, industrial, or other wastes for which a NPDES permit has been issued by the MPCA that contains effluent limits more stringent than those that would be established by parts 7053.0215 to 7053.0265 shall continue to meet the effluent limits established by the permit, 17
unless the permittee establishes that less stringent effluent limits are allowable pursuant to federal law, under section 402(o) of the Clean Water Act, United States Code, title 33, section 1342. 18