Please note that comment letters submitted to the MPCA do become public documents and will be part of the official public record for this project.

Transcription

1 September 9, 1999 TO INTERESTED PARTIES: RE: Northfield Wastewater Treatment Facility Improvements Enclosed is the Environmental Assessment Worksheet (EAW) for the proposed Northfield Wastewater Treatment Facility, Dakota County. The EAW was prepared by the Minnesota Pollution Control Agency (MPCA) and is being distributed for a 30-day review and comment period pursuant to the Environmental Quality Board (EQB) rules. The comment period will begin the day the EAW availability notice is published in the EQB Monitor, which will likely occur in the September 20, 1999, issue. Comments received on the EAW will be used by the MPCA in evaluating the potential for significant environmental effects from this project and deciding on the need for an Environmental Impact Statement (EIS). A final decision on the need for an EIS will be made by the MPCA Commissioner after the end of the comment period. If a request for an EIS is received during the comment period, or if the Commissioner recommends the preparation of an EIS, the nine-member MPCA Citizens Board (Board) will make the final decision. The final EIS need decision will also be made by the Board if so requested by the project proposer, other interested parties or MPCA staff and if this request is agreed to by one or more members of the Board or the MPCA Commissioner. The Board meets once a month, usually the fourth Tuesday of each month, at the MPCA office in St. Paul. Meetings are open to the public and interested persons may offer testimony on Board agenda items. A listing of Board members is available on request by calling (651) Please note that comment letters submitted to the MPCA do become public documents and will be part of the official public record for this project. If you have any questions on the EAW, please contact Lynne Kolze of my staff at (651) Sincerely, Joseph L. Esker District Planning Supervisor Operations and Planning Section Metro District JLE:sjs Enclosure

2 AMENDED NOVEMBER 15, 1999 ENVIRONMENTAL ASSESSMENT WORKSHEET Note to preparers: An electronic version of this form is available at A booklet, EAW Guidelines, is also available at the web site or by calling The Environmental Assessment Worksheet (EAW) provides information about a project that may have the potential for significant environmental effects. The EAW is prepared by the Responsible Governmental Unit (RGU) or its agents to determine whether an Environmental Impact Statement (EIS) should be prepared. The project proposer must supply any reasonably accessible data for but should not complete the final worksheet. If a complete answer does not fit in the space allotted, attach additional sheets as necessary. The complete question as well as the answer must be included if the EAW is prepared electronically. Note to reviewers: Comments must be submitted to the RGU during the 30-day comment period following notice of the EAW in the Minnesota Environmental Quality Board (EQB) Monitor. Comments should address the accuracy and completeness of information, potential impacts that warrant further investigation and the need for an EIS. 1. Project Title: Northfield Wastewater Treatment Facility (WWTF) Improvements 2. Proposer: City of Northfield 3. RGU: Minnesota Pollution Control Agency (MPCA) Contact Person Jon Peterson, Bolton and Contact Person Lynne Kolze Menk, Inc. and Title Consultant and Title Planner Principal Address 515 North Riverfront Drive Address 520 Lafayette Road North Mankato, MN St. Paul, Minnesota Phone Phone (651) Fax Fax 4. Reason for EAW Preparation: EIS Scoping X Mandatory EAW Citizen Petition RGU Discretion Proposer Volunteered If EAW or EIS is mandatory give EQB rule category subpart number: Minnesota Rules Part and subpart 18B 5. Project Location: County Dakota City/Twp Northfield NW 1/4 SE 1/4 Section 30 Township T112N Range R19W TDD (for hearing and speech impaired only): (651) Printed on recycled paper containing at least 10% fibers from paper recycled by consumers

3 Attach each of the following to the EAW: Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 State of Minnesota map showing location of project. Existing Wastewater Treatment Site Boundary Map. Site Plan of Existing WWTF. Site Plan of Proposed WWTF. US Geological Survey 7.5 minute, 1:24,000 scale map indicating project boundaries. Minnesota Department of Natural Resources (DNR) Natural Heritage Database letter. Flow Schematic for proposed WWTF. 6. Description: a. Provide a project summary of 50 words or less to be published in the EQB Monitor. The city of Northfield proposes to expand its existing WWTF. The new facility would rely on innovative technologies to treat projected wastewater flows. At design flow, the proposed facility would treat a design average wet weather (AWW) flow of 5.2 million gallons per day (mgd). b. Give a complete description of the proposed project and related new construction. Attach additional sheets as necessary. Emphasize construction, operation methods and features that would cause physical manipulation of the environment or would produce wastes. Include modifications to existing equipment or industrial processes and significant demolition, removal or remodeling of existing structures. Indicate the timing and duration of construction activities. The city of Northfield is proposing to expand its existing (WWTF) in order to accommodate a projected population increase of 8,700 people over the next 20 years. Currently, the facility s design AWW flow is 3.4 mgd. By the year 2020, the WWTF would need to treat an AWW flow of 5.20 mgd. The existing WWTF site (Figures 1 & 2) is not large enough to accommodate a significant expansion of traditional treatment processes. Rather than purchase a new piece of property for the expanded facility, the city opted for construction of an innovative wastewater treatment process that would require less land area while providing exceptional treatment of wastewater and sludges. The City s existing WWTF consists of : 1) pretreatment, which removes grit and large objects; 2) primary treatment, which removes easily settled solids and organics; 3) trickling filters, which provide biological treatment of the wastewater; 4) submerged and rotating biological contactors, which provide additional biological treatment; 5) final clarifiers which allow most remaining solids to be settled out; and 6) ultraviolet disinfection which kills potential pathogens in effluent (Figure 3). The new treatment system would consist of: 1) preliminary treatment consisting of fine screening and grit removal to remove objects and grit; 2) rapid mix and flocculation tanks for enhanced settling of suspended material in the lamella clarifiers; 3) lamella plate clarifiers for intermediate settling; 4) upflow fixed film biological aerated filters (BAF) to provide biological treatment and polishing; and 5) ultraviolet disinfection to kill potential pathogens in the effluent prior to its discharge to the Cannon River. Sludge generated by the clarifiers and biological processes would be treated with a lime pasteurization system to achieve a Class A biosolids. This classification enables the sludge to be used as fertilizer with few restrictions (Figure 4). The existing trickling filters and submerged biological contactors would be reused in the expanded facility for a portion of the waste stream. The lamella plate clarifiers, the BAF, and aerobic sludge digestion system would be new equipment and would replace other processes at the existing facility. The WWTF s existing outfall structure will not be altered in any way. Wet scrubbers would be incorporated into the facility design to provide odor control. 2

4 The City anticipates accepting bids late in 1999 or early Construction is expected to begin in 2000 and be completed in c. Explain the project purpose; if the project would be carried out by a governmental unit, explain the need for the project and identify its beneficiaries. Northfield s existing WWTF is currently at design flow. Population growth projections indicate that the existing treatment facility would be unable to handle flow increases over the next 20 years. The City must now plan for future wastewater treatment needs. The city of Northfield has the legal authority to construct and operate the proposed facility improvements. The beneficiaries would be residential, commercial, and industrial sectors in the city of Northfield. d. Are future stages of this development including development on any outlots planned or likely to happen? Yes No If yes, briefly describe future stages, relationship to present project, timeline and plans for environmental review. e. Is this project a subsequent stage of an earlier project? Yes No If yes, briefly describe the past development, timeline and any past environmental review. The WWTF was last modified in Project Magnitude Data Total Project Area (acres) 5 or Length (miles) N/A Number of Residential Units: Unattached N/A Attached maximum units per building Commercial/Industrial/Institutional Building Area (gross floor space): total square feet Indicate area of specific uses (in square feet): Office N/A Manufacturing N/A Retail N/A Other Industrial N/A Warehouse N/A Institutional N/A Light Industrial N/A Agricultural N/A Other Commercial (specify) N/A Building height If over 2 stories, compare to heights of nearby buildings 8. Permits and approvals required. List all known local, state and federal permits, approvals and financial assistance for the project. Include modifications of any existing permits, governmental review of plans, and all direct and indirect forms of public financial assistance including bond guarantees, Tax Increment Financing and infrastructure. Unit of Government Type of Application Status MPCA Facility Plan Approval Pending MPCA MN State Revolving Loan Funding Approval Pending MPCA NPDES/SDS Permit Pending MPCA Plans and Specs Approval Pending MPCA NPDES Stormwater Permit To be submitted City of Northfield Review of Plans To be submitted Dakota County Building Permit To be submitted 9. Land use. Describe current and recent past land use and development on the site and on adjacent lands. Discuss project compatibility with adjacent and nearby land uses. Indicate whether any potential conflicts involve environmental matters. Identify any potential environmental hazards due to past site uses, such as soil contamination or abandoned storage tanks, or proximity to nearby hazardous liquid or gas pipelines. 3

5 The existing WWTF site has been used for wastewater treatment for the past 40 years. Land uses surrounding the WWTF site generally fall into the following categories: Rural residential, Urban residential, Wetlands, and Agricultural land (Figure 5). There are approximately 90 residences within a 1-mile radius of the WWTF site. The expansion of the WWTF would be done entirely within the existing WWTF property, so there should be minimal impacts from construction to nearby residences. Since the size of the facility would not change as a result of the expansion, no new land use conflicts should arise. In the past, this treatment facility has caused some odor problems for nearby residences. To reduce the potential for odor problems at the proposed facility, the City has included chemical wet scubbing technologies in the facility design. This is expected to eradicate any nuisance odors coming from the proposed processes. The MPCA Master Entity System (MES) was queried to determine whether there are any records of previous or existing soil contamination in the vicinity of the wastewater facility. The MES is a comprehensive database that includes the Metropolitan Area Disposal Site Inventory, the Outstate Dump Inventory, the Voluntary Investigation and Cleanup Inventory, as well as the files of the MPCA s remediation programs. The database had no records of previous soil contamination or storage tanks on this site. 10. Cover Types. Estimate the acreage of the site with each of the following cover types before and after development: Before After Before After Types 1-8 wetlands 0 0 Lawn/landscaping Wooded/forest 0 0 Impervious Surfaces Brush/grassland Other (describe) Cropland TOTAL Fish, Wildlife, and Ecologically Sensitive Resources a. Identify fish and wildlife resources and habitats on or near the site and describe how they would be affected by the project. Describe any measures to be taken to minimize or avoid impacts. There are significant fish and wildlife resources around the Northfield area. The Cannon River, which is the receiving water for this WWTF s effluent, was designated an Outstanding Resource Value Water (ORVW) in Within the vicinity of the WWTF site, the Cannon River provides important habitat for wood turtles, several species of freshwater mussels and numerous fish species. The chosen treatment system would ensure that beneficial uses of the ORVW are protected. At design flow, the expanded treatment plant would discharge the same permitted mass load of pollutants as the existing facility, so fish and other aquatic wildlife would continue to be protected. In addition, by selecting an innovative treatment process, the expansion can be constructed within the same footprint of the existing facility. As a result, the city was able to avoid impacting other open space within the city limits. b. Are any state (endangered or threatened) species, rare plant communities or other sensitive ecological resources such as native prairie habitat, colonial waterbird nesting colonies or regionally rare plant communities on or near the site? Yes No If yes, describe the resource and how it would be affected by the project. Indicate if a site survey of the resources has been conducted and describe the results. If the Department of Natural Resources (DNR) Natural Heritage and Nongame Research program has been contacted give the correspondence reference number Describe measures to minimize or avoid adverse impacts. One threatened species of plant has been located within a one-mile radius of the WWTF site (Figure 6). The Scutellaria Ovata (Ovate Laeved Skullcap) has been located in the Cowling Arboretum, Carlton College 4

6 campus. However, the arboretum is sufficiently far from the WWTF that no harm can come to these particular rare plant specimens. 12. Physical Impacts on Water Resources. Would the project involve the physical or hydrologic alteration dredging, filling, stream diversion, outfall structure, diking, and impoundment of any surface waters such as a lake, pond, wetland, stream or drainage ditch? Yes No If yes, identify water resource affected. Describe alternatives considered and proposed mitigation measures to minimize impacts. Give the DNR Protected Waters Inventory (PWI) number(s) if the water resources affected are on the PWI. The existing WWTF s outfall runs north from the wastewater plant approximately 230 feet and then discharges to the Cannon River. There would be no changes made to the existing outfall during expansion of the WWTF. 13. Water Use Would the project involve installation or abandonment of any water wells, connection to or changes in any public water supply or appropriation of any ground or surface water (including dewatering)? Yes No If yes, as applicable, give location and purpose of any new wells; public supply affected, changes to be made, and water quantities to be used; the source, duration, quantity and purpose of any appropriations; and unique well numbers and DNR appropriation permit numbers, if known. Identify any existing and new wells on the site map. If there are no wells known on site, explain methodology used to determine. 14. Water-related land use management districts.. Does any part of the project involve a shoreland zoning district, a delineated 100-year flood plain, or a state or federally designated wild or scenic river land use district? Yes No If yes, identify the district and discuss project compatibility with district land use restrictions. This portion of the Cannon River has been designated a Wild and Scenic River under Minn. R The rules and regulations governing management of the Cannon River are The Cannon River Management Plan (Minn. R ) and the city of Northfield Zoning Ordinances for the Wild and Scenic River District (Section 1300:617, Subp. 5 (1) (A)(i.-iv.). These rules and ordinances limit the percentage of a site that can be impervious (limited to 30 percent or less), limit maximum building height (to be no higher than 35 feet), and the grading and filling that can be done within the 1000 feet ordinary high water mark. The proposed project would meet all of the provisions of these rules and ordinances. 15. Water Surface Use. Would the project change the number or type of watercraft on any water body? Yes No If yes, indicate the current and projected watercraft usage and discuss any potential overcrowding or conflicts with other uses. 16. Erosion and Sedimentation. Give the acreage to be graded or excavated and the cubic yards of soil to be moved: 5 acres; ~1500 cubic yards. Describe any steep slopes or highly erodible soils and and identify them on the site map. Describe any erosion and sedimentation control measures to be used during and after project construction. Because 5 acres of soil would be disturbed during expansion of the plant, the city would need to obtain a MPCA National Pollutant Discharge Elimination System (NPDES) Stormwater Permit. While the topography of the project site is quite flat, stormwater Best Management Practices would be implemented as a preventive measure. These practices would include silt fences, bale checks, and resodding disturbed areas according to the requirements outlined in the NPDES Stormwater Permit. 17. Water Quality - Surface Water Runoff 5

7 a. Compare the quantity and quality of site runoff before and after the project. Describe permanent controls to manage or treat runoff. Describe any storm water pollution prevention plans. Since the site is relatively flat, runoff quantity and quality is not expected to change significantly during or after construction. During construction, runoff would be controlled with silt fences and bale checks. After construction, vegetation would be reestablished on the site. Any surface runoff that does leave the site would receive natural treatment in the grassy and brushy swales near the plant. b. Identify routes and receiving water bodies for runoff from the site; include major downstream water bodies as well as the immediate receiving waters. Estimate impact runoff on the quality of receiving waters. Runoff currently flows eastwardly toward the Cannon River. After construction, runoff is expected to be very limited as the site is very flat and vegetation would absorb the majority of surface water moving toward the river. 18. Water Quality: wastewaters a. Describe sources, composition and quantities of all sanitary, municipal and industrial wastewater produced or treated at the site. Northfield WWTF is a regional wastewater treatment facility, treating wastes from Northfield and the city of Dundas. The expanded WWTF would continue to treat both sanitary and industrial wastes from the city of Northfield and sanitary wastes from the city of Dundas. Projected flow for the facility can be broken down as follows: Northfield Dundas Total Year 2020 (AWW Flow) 5.06 mgd 0.14 mgd 5.20 mgd All major industries within Northfield have pretreatment agreements with the City. Currently, the WWTF has an average dry weather flow of 2.0 mgd and an AWW of 3.4 mgd. The wastewater plant currently treats an average of 2,800 lbs. of biochemical oxygen demanding (CBOD) substances and 2,400 lbs. of total suspended solids (TSS) each day. At design flow in 2020, the plant would treat an average of 5,600 lbs. of CBOD and 5,000 lbs. of TSS per day. b. Describe waste treatment methods or pollution prevention efforts and give estimates of composition after treatment. Identify receiving waters, including major downstream water bodies, and estimate the discharge impact on the quality of receiving waters. If the project involves on-site sewage systems, discuss the suitability of site conditions for such systems. As wastewater enters the treatment facility, it would be fine screened to remove any large objects and then would undergo a grit separation process. The wastewater would be mixed and particles would be allowed to flocculate prior to entering the lamella plate clarifiers. In the clarifiers, solids generated during the previous process would be allowed to settle. Phosphorus removal would be accomplished through chemical addition in the clarifier. Biological treatment would be provided in an upflow fixed film biological aerated filter. Effluent would then be disinfected with ultraviolet disinfection before effluent is discharged to the Cannon River (Figure 7). This portion of the Cannon River has been classified by the MPCA as an ORVW. Therefore, any facility expanding within this portion of the river must meet certain requirements. Specifically, nondegradation rules prohibit any additional loading of pollutants to the river beyond that which was allowed when the ORVW was 6

8 designated in In essence, this facility s pollutant mass load to the Cannon River is permanently frozen at 1984 levels. In other words, the expanded WWTF would not discharge regulated pollutants in amounts greater than allowed under the existing permit. Phosphorus has not previously been a regulated pollutant in the Northfield NPDES permit. MPCA is currently giving greater consideration to the potential impacts of phosphorus on all surface waters in the state, especially ORVWs. In this case, Northfield discharges to the Cannon River upstream of Lake Byllesby. Lake Byllesby is hypereutrophic (an overly enriched environment with respect to nutrients). The lake currently exhibits conditions that would make it likely to experience severe nuisance algal blooms. The lake is already receiving excessive amounts of phosphorus from a variety of sources. The lake s phosphorus concentration is currently about mg/l. The water quality goal for lakes in the Western Cornbelt Plains ecoregion is mg/l. In an effort to reduce phosphorus contributions to the lake, it would be necessary to apply a 1.0 mg/l (monthly average) effluent phosphorus limitation to the facility upon construction. Without the limitation, the expanded facility may have the potential to contribute about 25 percent of the phosphorus load to the lake during low flow conditions. In addition to removing phosphorus at the Northfield WWTF, other point and nonpoint sources of phosphorus will need to be reduced in order to achieve the phosphorus goal for the lake. The proposed facility must consistently achieve the following effluent limitations at design flow*: Substance or Characteristic Monthly Average (mg/l) or Range Mass Loading CBOD5 16 mg/l 322 kg/day Total Suspended Solids 20 mg/l 386 kg/day Fecal Coliform (March- October) 200 orgs./100 ml NA ph NA Ammonia June-September 8.9 mg/l October-November 34 mg/l April-May 20 mg/l Copper 113 ug/l (daily maximum) 1.45 kg/day Cyanide amenable to chlorination quarterly monitoring NA Lead quarterly monitoring NA Total Phosphorus 1.0 mg/l monthly average** 7000 kg/year *It is important to note that the expanded facility s NPDES permit will initially have effluent limits of 25 mg/l CBOD and 30 mg/l TSS because flow will be much lower than at design flow. Once the facility reaches design flow, the permit will include the effluent limits referenced above. **The 1.0 mg/l concentration limit applies to any monthly average flow up to and including the proposed AWW design flow. c. If wastes would be discharged into a publicly owned treatment facility, identify the facility, describe any pretreatment provisions and discuss the facility s ability to handle the volume and composition of wastes, identifying any improvements necessary. Not applicable d. If the project requires disposal of liquid animal manure, describe disposal technique and location and discuss capacity to handle the volume and composition of manure. Identify any improvements necessary. Describe any required setbacks for land disposal systems. Not applicable: 7

9 19. Geologic hazards and soil conditions a. Approximate depth (in feet) to ground water: 10 ft. minimum; 10 average. bedrock: minimum; >60 ft. average. Describe any of the following geologic site hazards to ground water and also identify them on the site map: sinkholes, shallow limestone formations or karst conditions. Describe measures to avoid or minimize environmental problems due to any of these hazards. The exact depth to bedrock on the facility site is unknown. Soil borings were taken at the site at depths of up to 60 feet. No bedrock was encountered when these borings were taken. Generally, in this region, bedrock is found at a depth of less than 50 feet. Within the Cannon River Valley, however, sand and gravel deposits are more typically found at these depths. The depth of bedrock at the site should not impact actual construction of the proposed facility in any way. No hazards are known to exist on the site. Potential for ground water contamination would be minimal, as wastewater would be contained in process tanks and never come into contact with the soil. In addition, all new process tanks and piping would be leak tested with clean water to ensure that they are water tight before actual use. b. Describe the soils on the site, giving Soil Conservation Service classifications, if known. Discuss soil granularity and potential for groundwater contamination from wastes or chemicals spread or spilled onto the soils. Discuss any mitigation measures to prevent such contamination. Soils in the general vicinity of the WWTF site are sandy loams in the Estherville and Zumbro series. Both soils are well drained. On the proposed WWTF site, the soils consist mainly of previously disturbed soil and granular backfill. These soils do not pose any limitations for construction of the facility. 20. Solid Wastes, Hazardous Wastes, Storage Tanks a. Describe types, amounts and compositions of solid or hazardous wastes, including solid animal manure, sludge and ash, produced during construction and operation. Identify method and location of disposal. For projects generating municipal solid waste, indicate if there is a source separation plan; describe how the project would be modified for recycling. If hazardous waste is generated, indicate if there is a hazardous waste minimization plan and routine hazardous waste reduction assessments. The facility would generate sludge, otherwise known as biosolids, during the treatment process. In the year 2020, a total of 6,000 lbs. of biosolids would be produced each day. The biosolids would be treated to achieve Class A biosolids. The Class A rating indicates that the sludge has been extensively treated to essentially eliminate any health risks associated with pathogens in the material. Biosolids are currently and would continue to be land applied. The City currently has some agreements in place with landowners, but would have to develop additional land application contracts in the future. An additional 300 acres of land would be needed to accommodate sludges produced by the expanded facility. b. Identify any toxic or hazardous materials to be used or present at the site and identify measures to be used to prevent them from contaminating groundwater. If the use of toxic or hazardous materials would lead to a regulated waste, discharge or emission, discuss any alternatives considered to minimize or eliminate the waste, discharge or emission. Not applicable. c. Indicate the number, location, size and use of any above or below ground tanks to store petroleum products or other materials, except water. Describe any emergency response containment plans. 8

10 No petroleum products would be stored on the site. All the process tanks would hold wastewater. 21. Traffic. Parking spaces added Existing spaces (if project involves expansion) Estimated total average daily traffic generated Estimated maximum peak hour traffic generated (if known) and its timing: Provide an estimate of the impact on traffic congestion affected roads and describe any traffic improvements necessary. If the project is within the Twin Cities metropolitan area, discuss its impact on the regional transportation system. While the facility s design flow will be increasing significantly, traffic associated with the facility s operations is expected to decrease. This is due to proposed modifications to treatment and handling of biosolids at the facility. While it is expected that the dry mass of biosolids will increase over the design life of the facility, the new treatment process would produce a cake end product, which has a 40% biosolid mass instead of the current liquid product which has a biosolid mass of 5%. This results in greater efficiency in hauling the biosolids and ultimately fewer truck trips to remove it from the facility. The distribution of traffic over the year will likely change as a result of the proposed expansion. Currently, biosolids are hauled from the facility site 1-2 times per year, with each hauling period lasting approximately 2 weeks. Proposed plans would require that biosolids be hauled off site on a weekly or monthly basis. Thus traffic going to and from the facility would be spaced out more regularly over the year. 22. Vehicle-related Air Emissions. Estimate the effect of the project s traffic generation on air quality, including carbon monoxide levels. Discuss the effect of traffic improvements or other mitigation measures on air quality impacts. Note: If the project involves 500 or more parking spaces, consult EAW Guidelines about whether a detailed air quality analysis is needed. Not applicable. 23. Stationary Source Air Emissions. Describe the type, sources, quantities and compositions of any emissions from stationary sources of air emissions such as boilers, exhaust stacks or fugitive dust sources. Include any hazardous air pollutants (consult EAW Guidelines for a listing), any greenhouse gases (such as carbon dioxide, methane, and nitrous oxides), and ozone-depleting chemicals (chlorofluorocarbons, hydrofluorocarbons, perfluorocarbons or sulfur hexafluoride). Also describe any proposed pollution prevention techniques and proposed air pollution control devices. Describe the impacts on air quality. The only stationary source of air emissions at the wastewater facility site would be an emergency backup generator. This would be a 1,250 Kilowatt generator, housed in the existing garage space of the facility. This type of generator does not require a special permit from the MPCA. 9

11 24. Odors, noise and dust. Would the project generate odors, noise or dust during construction or during operation? Yes No If yes, describe sources, characteristics, duration, quantities or intensity and any proposed measures to mitigate adverse impacts. Also identify locations of nearby sensitive receptors and estimate impacts on them. Discuss potential impacts on human health or quality of life. (Note: fugitive dust generated by operations may be discussed at item 23 instead of here.) Odors Current treatment processes have caused odor problems for nearby receptors. Odors are caused by heavy organic loads to the facility where existing treatment processes have not been able to properly handle the generated odors. The existing facility does not currently have any odor control equipment in place, however, the city is in the process of installing odor control equipment to address odor problems while construction of the expanded facility is taking place. In addition, the City is working with industries in the area to periodically limit the amount of organic wastes being discharged to the WWTF. This should reduce the potential for odor problems in the short- term The new facility would be entirely enclosed in buildings. Air discharged from the facility would be processed through chemical wet scrubbing equipment. This equipment is expected to provide excellent odor control at the site. Noise -- Noise would be generated during construction of the new facility. The duration of noise caused by heavy equipment such as bulldozers, loaders, etc. would be approximately one year. The intensity of noise should not be significant since there are no sensitive receptors near the site. Dust Dust generated during construction would be controlled by a water truck. Water would be used to settle dust before it can become airborne. 25. Nearby resources. Are any of the following resources on or in proximity to the site? a. Archaeological, historical, or architectural resources? Yes No b. Prime or unique farmlands or land within an agricultural preserve? Yes No c. Designated parks, recreation areas, or trails? Yes No d. Scenic views and vistas? Yes No e. Other unique resources? Yes No If yes, describe the resource and identify any project-related impacts on the resources. Describe any measures to minimize or avoid adverse impacts. 26. Visual impacts. Would the project create adverse visual impacts during construction or operation? Such as glare from intense lights, lights visible in wilderness areas and large visible plumes from cooling towers or exhaust stacks? Yes No If yes, explain. 27. Compatibility with plans and land use regulations. Is the project subject to an adopted local comprehensive plan, land use plan or regulation, or other applicable land use, water, or resource management plan of a local, regional, state or federal agency? Yes No If yes, describe the plan, discuss its compatibility with the project and explain how any conflicts would be resolved. If no, explain. The proposed project is recommended in the City s Facility Plan, which has been approved by the city council and submitted to the MPCA for approval. 10

12 28. Impact on infrastructure and public services. Would new or expanded utilities, roads, other infrastructure or public services be required to serve the project? Yes No If yes, describe the new or additional infrastructure or services needed. (Note: any infrastructure that is a connected action with respect to the project must be assessed in the EAW; see EAW Guidelines for details.) 29. Cumulative impacts. Minn. R , subp. 7, item B, requires that the RGU consider the cumulative potential effects of related or anticipated future projects when determining the need for an environmental impact statement. Identify any past, present or reasonably foreseeable future projects that may interact with the project described in this EAW in such a way as to cause cumulative impacts. Describe the nature of the cumulative impacts and summarize any other available information relevant to determining whether there is potential for significant environmental effects due to cumulative impacts (or discuss each cumulative impact under appropriate item(s) elsewhere on this form). The expansion of the WWTF in Northfield would enable further residential, commercial and industrial growth within the City over the next 20 years. That development would cause an increase in impervious surfaces and increases in stormwater runoff. Even if stormwater management practices were utilized, there would likely be some degradation in surface water quality in the area as a result of development. The number of people residing in this area and automobile traffic would increase as a result of new development. In addition, development would likely reduce the amount of farmland, open space and wildlife habitat in the city of Northfield. 30. Other Potential Environmental Impacts. If the project may cause any adverse environmental impacts not addressed by items 1 to 28, identify and discuss them here, along with any proposed mitigation. There are no other known issues regarding the potential for environmental impacts at this site. 31. Summary of issues. Do not complete this section if the EAW is being done for EIS scoping; instead, address relevant issues in the draft Scoping Decision document, which must accompany the EAW. List any impacts and issues identified above that may require further investigation before the project is begun. Discuss any alternatives or mitigative measures that have been or may be considered for these impacts and issues, including those that have been or may be ordered as permit conditions. The proposed project involves expansion of an existing wastewater treatment plant in Northfield, Minnesota. Prior to selecting an approach for expanding the facility, the proposer considered a number of alternatives. These alternatives are listed below. The proposer s reasons for eliminating some as viable alternatives are also summarized. Discussion of Alternatives 1. No Action -- This approach did not appear viable since the existing facility (even running at peak efficiency) would not be expected to handle the projected increases in wastewater from the proposed developments in the city of Northfield. The no action alternative is not feasible for the planning area without revising current development plans. Although this alternative represents the lowest capital cost and least environmental disruption on a shortterm basis, long-term environmental impacts could result. Reliability and flexibility in operating the WWTF would decrease. There would be increased opportunities for operational failure and effluent quality may decrease over time. 11

13 2. Retrofit the existing Rotating Biological Contactors (RBCs) Calculations show that even with repiping influent lines to new RBC units, they would not have the capacity to meet proposed effluent limitations. 3. Convert the existing RBCs to Submerged Biological Contactors (SBCs) In order to convert the existing RBC units to SBCs, the walls of the existing RBC tanks would need to be raised significantly. In doing so, there would be very little headroom between the top of the tank and the ceiling. This would make operating these units difficult, if not impossible. The following alternatives each had advantages and disadvantages. A cost effectiveness analysis indicated that Alternative 7 be pursued. This alternative would also allow for future expansions at the same site. 4. Retrofit existing RBCs and add new SBCs 5. Demolish existing RBCs and add new SBCs 6. Demolish existing RBCs and add new Extended Aeration Basin 7. Demolish existing RBCs and construct Upflow Fixed Film Biological Filters Summary of Issues Item 11 - Fish and Wildlife Resources Because the facility must maintain a freeze on mass loadings of pollutants to the river, fish and other aquatic life in the Cannon River would not be significantly impacted by this expansion. Item 18 Water Quality/Waste Water The existing WWTF discharges into the Cannon River. This portion of the river has been classified by the MPCA as an ORVW. Therefore, any facility expanding within this portion of the river must meet certain requirements. Specifically, nondegradation rules prohibit any additional loading of pollutants to the river beyond that which was allowed when the ORVW was designated in The designated uses of the Cannon River near the facility would be maintained if the proposed effluent limits are consistently met. Phosphorus has not previously been a regulated pollutant in the Northfield NPDES permit. The MPCA is currently giving greater consideration to the potential impacts of phosphorus on all surface waters in the state, especially ORVWs. The city of Northfield has accepted MPCA s recommended 1 mg/l (monthly average) phosphorus effluent limit for the facility. Achieving the proposed phosphorus limit reflects a serious commitment on the part of the proposer to reduce their contribution of pollutants to the Cannon River. 12

14 RGU CERTIFICATION. The Environmental Quality Board would only accept SIGNED Environmental Assessment Worksheets for public notice in the EQB Monitor. I hereby certify that: The information contained in this document is accurate and complete to the best of my knowledge. The EAW describes the complete project; there are no other projects, stages or components other than those described in this document, which are related to the project as connected actions or phased actions, as defined at Minn. R , subps. 9b and 60, respectively. Copies of this EAW are being sent to the entire EQB distribution list. Name and Title of Signer: Joseph L. Esker, District Planning Supervisor, Operations and Planning Section, Metro District Date: Environmental Assessment Worksheet was prepared by the staff of the Environmental Quality Board at Minnesota Planning. For additional information, worksheets or for EAW Guidelines, contact: Environmental Quality Board, 658 Cedar St., St. Paul, MN 55155, , or 13