Rosemount Wastewater Treatment Plant Interim Improvements · There are four principal activities...

STATE OF MINNESOTA MINNESOTA POLLUTION CONTROL AGENCY

IN THE MATTER OF THE DECISION ON THE NEED FOR AN ENVIRONMENTAL IMPACT STATEMENT FOR THE PROPOSED ROSEMOUNT WASTEWATER TREATMENT PLANT INTERIM IMPROVEMENTS CITY OF ROSEMOUNT DAKOTA COUNTY, MINNESOTA

FINDINGS OF FACT CONCLUSIONS OF LAW AND ORDER

FINDINGS OF FACT Pursuant to Minn. R. 4410.1000 - 4410.1600 (1999), the Minnesota Pollution Control Agency (MPCA) staff has prepared an Environmental Assessment Worksheet (EAW) for the proposed project. Based on the MPCA staff environmental review, comments, and information received during the comment period, and other information in the record of the MPCA, the MPCA hereby makes the following Findings of Fact, Conclusions of Law, and Order:

FACILITY HISTORY Overview: The Metropolitan Council Environmental Services (MCES) Division is proposing to modify an existing aerated stabilization pond system. The modification will increase the capacity of the existing facility in Dakota County to 1.41 million gallons per day. The improvements will extend the design life of the facility for about five years, until implementation of the Master Plan for wastewater services in the area. The existing facility (facility) is a three-cell aerated pond system with a continuous discharge to Spring Lake, a backwater lake in the Mississippi River that is considered part of Navigation Pool No. 2. The proposed improvements include the construction of fabric baffles to increase serpentine flow in the ponds, addition of floating aerators, construction of a small chemical addition tank between cells, and replacement of chlorine disinfection with ultraviolet light disinfection. Permitting History: A physical-chemical treatment plant was constructed in the early 1970’s near the site of the aerated stabilization pond. The aerated stabilization pond itself was permitted in the late 1980’s and began operation in 1989. Previous Environmental Review: The facility has not previously been of sufficient size to require environmental review. Compliance/Enforcement History:

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Rosemount Wastewater Treatment Plant Interim Improvements Findings of Fact Rosemount, Minnesota Conclusions of Law And Order

The facility has been in compliance with effluent limits in the last year.

PROPOSED PROJECT DESCRIPTION Proposed New Construction/Proposed Modification:

Current estimates of growth in the Rosemount service area indicate that the facility will reach its design capacity in 2002. In order to continue treatment service to the Rosemount area, some interim improvements are proposed which will enhance treatment with minimal new construction. To enhance treatment in Cells 1 and 2, longitudinal baffles will be added. The existing floating aerators will be relocated in Cell 1 to supplement air in the first pass inlet. Additional aerators will be added to Cell 2. Outlet pipes in the cells will be modified to enhance the serpentine flow pattern. Chemical addition and rapid mix facilities will be added between Cells 2 and 3 to allow alum addition for phosphorus removal. The existing chlorine disinfection facilities will be replaced with ultraviolet disinfection. There are four principal activities associated with construction of the Wastewater Treatment Plant (WWTP) improvements:

• Work within the existing aerated cell consisting of fabric baffle construction and pipe relocation; • Construction of small at-grade treatment tanks for chemical addition and mixing and ultraviolet

disinfection. This work will be accomplished with open pit construction and tank construction using cast-in-place concrete or precast structures;

• Construction of a chemical feed and storage building with a total building area of approximately 900

square feet. This building is to be a single story metal frame structure constructed on a spread-footing foundation; and

• Miscellaneous piping modifications and underground utilities (water service, electrical service,

chemical feed piping, and process piping to be constructed by open trench construction). All excess excavated materials will be redistributed on the site. The construction period will last approximately six months.

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Environmental Concerns: The following environmental issues were identified and addressed during preparation of the EAW, in comments on the EAW, in responding to those comments, and during preparation of these Findings:

• Potential traffic congestion and air quality effects resulting from enabled development; • Surface water runoff and water quality and other effects resulting from enabled development, and

the adequacy of local storm water management programs to deal with those effects; • Water quality impacts from the discharge of mercury; and • Water quality impacts from the discharge of phosphorus into Spring Lake.

Permitting Requirements: A National Pollution Discharge Elimination System (NPDES) Permit and an NPDES general construction storm water permit will be required by the MPCA. The MPCA also requires submission of construction plans and specifications for review and approval. The city of Rosemount (City) will require a Building Permit. All permits must be issued prior to the start of construction for the proposed expansion. Additional Concerns Described in Comment Letters: • The MCES took exception to the MPCA’s determination that the facility discharged to Spring Lake,

and thus was assigned a 1 milligram per liter (mg/L) effluent phosphorus limitation pursuant to Minn. R. 7050.0211, subpart 1. However, MCES has accepted a 1 mg/L effluent phosphorus limit, but the MCES stated that “…we do think that the agency’s determination of regulatory applicability is incorrectly derived and is not supported by a determination of “affects”. Therefore, it would be more appropriate to reference Council Strategy as the reason for the anticipated effluent limitation.”

This comment was responded to in Response 2-5 of the Response to Comments.

• MCES also took exception to the intention of the MPCA staff to impose an interim mercury effluent

limitation, set at a “level currently achievable” after one year of effluent monitoring. Their understanding was that there would be no applicable effluent limitation during the variance period.

This comment was responded to in Response 2-6 of the Response to Comments.

• Dakota County Office of Planning provided clarification as to the nature of Watershed Management

organization in the area. They also indicated that the EAW should have explained the potential for ground water contamination.

Both comments were responded to in the Second Errata Sheet to the EAW.

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Community Involvement in Process: Community involvement in the process has consisted of publication of the EAW Notice of Availability in the Environmental Quality Board (EQB) Monitor, distribution of the EAW to interested parties, and receipt of public comments. In addition, the MCES has conducted public meetings during the development of the Master Plan for wastewater treatment in the Empire/Rosemount service areas.

PROCEDURAL HISTORY 1. Pursuant to Minn. R. 4410.4300 subp. 18, an EAW was prepared by MPCA staff on the proposed

project. Pursuant to Minn. R. 4410.1500 (1999), the EAW was distributed to the EQB mailing list and other interested parties on February 2, 2001. An EAW Errata Sheet was mailed to the same recipients on February 14, 2001.

2. The MPCA notified the public of the availability of the EAW for public comment. A news release

was provided to news media in the Twin Cities Metropolitan Area on February 5, 2001. In addition, the EAW was published in the EQB Monitor on February 5, 2001, and available for review on the MPCA website at pca.state.mn.us on February 5, 2001.

3. The public comment period for the EAW began on February 5, 2001, and ended on March 7, 2001.

The MPCA received five comment letters from government agencies and received no comment letters from citizens during the 30-day public comment period.

4. The MPCA prepared responses to all comments received during the 30-day public comment period.

Comment letters received have been hereby incorporated by reference in Appendix A. Responses to comments received have been prepared by MPCA staff and are incorporated by reference in Appendix B.

5. In the Spring of 2001, MPCA staff became aware of an incident of construction-related erosion,

runoff sedimentation, and flooding that impacted a Minnesota Department of Natural Resources (DNR) protected water in the project’s service area. Because this was a significant environmental effect that occurred in an area where wastewater collection and treatment enabled residential development, lengthy discussions were held by the MPCA, the DNR, and several other parties. The preparation of these Findings of Fact was delayed by these discussions.

CRITERIA FOR DETERMINING THE POTENTIAL FOR

SIGNIFICANT ENVIRONMENTAL EFFECTS 6. Under Minn. R. 4410.1700, subp. 1 (1999), the MPCA must order an Environmental Impact

Statement (EIS) for projects that have the potential for significant environmental effects that are reasonably expected to occur. In deciding whether a project has the potential for significant environmental effects, the MPCA must compare the impacts that may be reasonably expected to occur from the project with the criteria set forth in Minn. R. 4410.1700, subp. 7 (1999). These criteria are:

A. the type, extent, and reversibility of environmental effects;

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B. cumulative potential effects of related or anticipated future projects; C. the extent to which the environmental effects are subject to mitigation by ongoing public

regulatory authority; and D. the extent to which environmental effects can be anticipated and controlled as a result of other

available environmental studies undertaken by public agencies or the project proposer, including other EISs.

THE MPCA FINDINGS WITH RESPECT TO EACH OF THESE CRITERIA

ARE SET FORTH BELOW Type, Extent, and Reversibility of Environmental Effects 7. The first criterion that the MPCA must consider, when determining if a project has the potential for

significant environmental effects that are reasonably expected to occur, is the "type, extent, and reversibility of environmental effects" Minn. R. 4410.1700, subp. 7.A (1999). The MPCA findings with respect to each of these factors are set forth below.

• Traffic congestion and deterioration of air quality as a result of development enabled by the project Type and nature of the effect:

8. It can be reasonably expected that this project could potentially result in traffic congestion and deterioration of air quality as a result of residential and other development enabled by the availability of wastewater collection and treatment capacity. As traffic increases, so also does congestion. With congestion, the level of service deteriorates and air quality is impacted by idling vehicles and the number of vehicles.

Extent of the effect:

9. The extent of any traffic congestion and resultant air quality deterioration reasonably expected to

occur as a result will depend upon the development density, the existing and future transportation infrastructure, land use planning, and impacts mitigation.

10. Traffic congestion and air quality degradation resulting from residential development enabled by

the construction of additional wastewater treatment capacity are subject to mitigation. If traffic increases result locally in deterioration in levels of service and violations of ambient air quality standards, mitigative measures are available. These include: roadway improvements (additional lanes, turn lanes), signal installation, and provision of alternative transportation choices. These mitigative measures are routine measures that are a part of the transportation elements of the comprehensive plan of the city of Rosemount. They are implemented routinely as communities undergo development.

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Reversibility of the effect:

11. Enabled residential development is not reversible. However, any traffic congestion and air quality

impacts resulting from vehicular traffic from enabled development are reversible, or even preventable, provided appropriate mitigation measures are employed. As discussed in Finding 10, the expected effects on air quality after mitigation are minimal. There is no reason to believe that this project is reasonably expected to cause a significant negative effect on air quality.

Comments received relating to the effect:

12. No comment letters were received that expressed general or specific concern about impacts of the project on air quality. The MPCA staff raised the issue in the EAW.

13. The MPCA finds that the environmental review is adequate to address concerns relating to air

quality because all potential impacts to air quality that are reasonably expected to occur from development enabled by the proposed expansion of this facility have been considered by MPCA staff during the review process and methods to prevent these impacts have been identified.

14. The MPCA finds that the project does not have the potential for significant environmental effects

based on the type, extent, and reversibility of environmental effects reasonably expected to occur as a result of vehicular air emissions associated with traffic from development enabled by the project.

• Water quality impacts associated with storm water impacts from enabled development.

Type and nature of the effect: 15. Increases in storm water runoff can be reasonably expected to result from enabled residential and

other development enabled by this project. This runoff could adversely impact water quality. Storm water runoff volume, flow rates, and flow duration increase because of increased impervious surface (driveways, streets, roofs, and parking lots) in new development. Rainwater contains small concentrations of nutrients, which will then be carried in storm water runoff. Storm water runoff can entrain nutrients, which will result in algae growth, and it can cause erosion and sedimentation, which will result in increased turbidity. Increased volume and duration of runoff (“bounce”) may cause scouring of stream bottoms and banks, and may also result in short-term or even permanent increases in water levels in wetlands and lakes.


16. The extent of any potential water quality effects that are reasonably expected to occur will depend

upon several factors. These include development density, permeability of soils in the area, the amount of additional impervious surface that results from development, the extent to which wetlands and natural drainage ways are altered or preserved, and the various provisions made for storm water conveyance, storage, and treatment. Mitigation measures are usually included in the comprehensive plan and the specific storm water and development elements of that plan.

In this and other previous similar projects where such a concern has been raised, MPCA staff has included a discussion in the EAW of the adequacy of local storm water ordinances to minimize

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impacts on surface water quality. This information is addressed in the Nondegradation Review (part of the NPDES permit). In the EAW for this project, it is indicated that Rosemount’s storm water ordinances were reviewed and found to be protective of water quality. Their wetland preservation elements were reported as being among the best in the Metropolitan Area. However, in the spring of 2001, at one large development in Rosemount, substantial site grading had occurred so late in the growing season that it was impossible to re-establish vegetative cover. Subsequent winter and spring rainstorms caused a great deal of erosion, sedimentation, and water quality degradation in adjacent properties. Low areas adjacent to the development were inundated, and a DNR protected water was temporarily merged with a nearby private wetland. Large quantities of eroded sediment entered these wetlands. The incident is documented in Attachment A to these findings. The incident suggests that the Rosemount storm water ordinances were, in at least one instance, not sufficient to prevent a substantial impact on water quality from storm water. During discussions with the City, information about the circumstances leading up to the incident was obtained. The City also detailed, in a letter dated June 25, 2001, (Attachment B) what actions it had taken to prevent future occurrences. Those actions included the hiring of a Staff Water Resource Engineer to enforce the wetlands management plan, and enforce erosion control measures with developers and individual builders. The City has entered into an agreement with the Dakota Soil & Water Conservation District (DCS&WCD) to provide assistance with erosion control and wetland permitting issues. Attachment B also details other extensive City actions. All developments in Minnesota that result in the disturbance of more that 5 acres of vegetation are required to comply with the NPDES General Permit for storm water construction. This permit mandates best management practices to be employed during construction. Enforcement action was taken against the developer of the above-mentioned property.

Reversibility of effect:

17. Residential and other development enabled by the project is an intended result of the project and is

not reversible. As discussed above, the expected effects on water quality are minimal. There is no reason to believe that this project is reasonably expected to cause a significant negative effect on water quality. Comments received relating to the effect:

18. Both the DNR and the DCS&WCD submitted comment letters that expressed concern about water quality impacts from development enabled by the project. As discussed above in sections 15 and 16, the MPCA's staff analysis indicates that significant effects on water quality are not reasonably expected to occur.

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19. The MPCA finds that the environmental review is adequate to address the concerns. All potential

impacts to water quality that are reasonably expected to occur from the proposed expansion of this facility have been considered by MPCA staff during the review process and methods to prevent these impacts have been identified.

20. The MPCA finds that the project as it is proposed does not have the potential for significant

environmental effects on water quality based on the type, extent, and reversibility of environmental effects reasonably expected to occur.

• Water quality impacts from the discharge of mercury

Type and nature of the effect: 21. Mercury is a liquid metallic element that is highly toxic and that, under certain circumstances, can

result in contamination of the food web. Fish advisories are routinely issued for Minnesota lakes due to mercury contamination in fish. Mercury will tend to concentrate in the higher trophic levels, so that piscivorous species such as eagles and loons are subject to mercury poisoning. Mercury is ubiquitous (in small quantities) in the environment, and it has extensive commercial and industrial uses. Mercury is found in flue gases from coal-burning power plants and municipal waste combustors. Substantial amounts are deposited by wet and dry deposition. Mercury in wastewater influent comes from a variety of sources, including dental offices and human waste.


22. The effluent discharge is located in Spring Lake, and effluent will ultimately flow to a reach of the

Mississippi River that is on the 303(d) list as a water that is presently impaired due to elevated environmental mercury levels, primarily in the context of fish consumption advisories. In addition, this reach frequently exceeds the chronic mercury water quality standard.

Mercury can be removed from effluent during the treatment process. As part of the nondegradation review that was submitted for mercury in accordance with Minn. R. 7050.0185, MCES provided a cost-effectiveness analysis of two advanced treatment systems to remove mercury. One was sand filtration at a total present worth (5 years) of $1.8 million, and the second would employ microfiltration/reverse osmosis at a total present worth of about $16 million. Neither system would be guaranteed to produce an effluent that would meet the mercury limit. End-of-pipe treatment is not in this case the cost-effective approach to controlling mercury. It may lead to media transfer to the atmosphere by aeration. Filtration, precipitation, and reverse osmosis can generate a solid residue. Source control or pollution prevention activities keep mercury from getting into the collection system altogether, consistent with preferred MPCA policy.

The facility will discharge effluent containing mercury to Spring Lake and ultimately to the Mississippi River, in which the ambient standard for mercury is already exceeded. Further discharge of mercury that would cause or contribute to a water quality standards violation is prohibited. A variance from the mercury standard is therefore required. The conditions of the variance will provide details of measures to be taken so as to minimize mercury in the effluent.

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A variance request was submitted for mercury in accordance with Minn. R. 7050.0190 and Minn. R. 7000.7000. The request contained the appropriate information specified in Minn. R. 7000.7000, including detailed information on treatment alternatives and source controls/pollution prevention for mercury discussed in the nondegradation review. MCES further documented the inability to meet the proposed final mercury effluent limitation, providing monitoring data showing the limit is exceeded. The application has been determined to be complete, and staff recommends the variance be granted provided the permit contains mercury effluent limitations and pollutant minimization requirements. For the foreseeable future, MCES will employ source control strategies to demonstrate further reasonable progress towards attaining the effluent limit and the underlying water quality standard. An interim effluent limit, based on a “level currently achievable (LCA)”, will be placed in the permit. Should it be demonstrated that the final effluent limit is not attainable within this initial permit, a revised lower LCA should be determined when the permit is reissued. The final effluent limit will apply at a time when the variance is no longer applicable and the final limit is achieved. The initial LCA is determined by collecting one year of low level mercury data to establish a baseline, which will become the monthly average limit.

Reversibility of the effect:

23. Water quality impacts of mercury discharges are generally not reversible, even if the discharge is

discontinued. The mercury sequestered in sediment may reenter the water column under certain circumstances, becoming available to aquatic organisms.

Comment letters relating to the effect:

24. A comment letter was received from the DNR that expressed support of the MPCA staff’s

recommendation that a variance for mercury be granted ‘provided the permit contains mercury effluent limitations and pollutant minimization requirements.’ They recommended that the permit contain a special condition requiring submission of study results on the need for additional mercury treatment one year after initiation of operation of the updated facility. (See Appendix B, Response to Comment 3-2).

25. The MPCA finds that the environmental review is adequate to address concerns relating to water

quality effects of mercury in the effluent discharge because potential impacts to water quality that are reasonably expected to occur from the proposed expansion of this facility have been considered by MPCA staff during the review process. Methods to prevent these impacts (an interim effluent mercury limit and source reduction activities), have been identified.

26. The MPCA finds that the project, as it is proposed, does not have the potential for significant

environmental effects based on the type, extent, and reversibility of environmental effects reasonably expected to occur as a result of its discharge of mercury in the effluent.

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• Water quality impacts from the discharge of phosphorus to Spring Lake

Type and nature of the effect: 27. Phosphorus is a nutrient that enables the growth of algae in lakes and rivers. Excessive amounts of

phosphorus in aquatic systems have been shown to result in reduction in water clarity, increased oxygen demand and algae growth, and changes in trophic states of lakes, among other adverse impacts. Incremental increases in wastewater – associated nutrients cumulatively impact the water quality of the Mississippi River and ultimately of the Gulf of Mexico. Increasingly, phosphorus is a nutrient of concern.


28. The extent of water quality impacts from nutrient (particularly phosphorus) discharges will depend

on how much phosphorus is discharged. For facilities that discharge directly to a lake, a 1 mg/L effluent phosphorus limit is prescribed by Minn. R. 7050.0211, subpart 1a. For those that discharge upstream of a lake or reservoir, a water quality effect must be demonstrated. In such cases, a 1 mg/L effluent limit is generally assigned, although there have been a very small number of cases where it was demonstrated that a more restrictive limit was appropriate. As indicated in the EAW prepared on this project, previous modeling of this and nearby discharges of wastewater demonstrates that a 1 mg/L effluent phosphorus limit is reasonable and that a more stringent limit is not required.

29. The MPCA finds that a 1 mg/L effluent phosphorus limit is protective of the water quality in Spring

Lake and other downstream waters and that a more restrictive limit is unnecessary. The Nondegradation Review conducted in accordance with Minn. R. 7050.0185 resulted in a conclusion that, with the elimination of chlorine disinfection and the assignment of a 1 mg/L effluent phosphorus limit, no additional treatment was necessary.

Reversibility of the effect

30. Water quality impacts of phosphorus discharges are generally reversible, once the discharge is

discontinued. However, in cases where large quantities of phosphorus have been deposited in lake sediments, expensive and lengthy efforts may be required to remove or sequester the phosphorus in the sediments.

Comment letters pertaining to the effect:

31. A comment letter was received from the DNR that expressed support for a 1 mg/L effluent

phosphorus limit. 32. The MCES took exception to the MPCA’s determination that the facility discharged to Spring

Lake, and thus was assigned a 1 mg/L effluent phosphorus limitation pursuant to Minn. R. 7050.0211, subpart 1. However, MCES has accepted a 1 mg/L effluent phosphorus limit, but they stated “…we do think that the agency’s determination of regulatory applicability is incorrectly derived and is not supported by a determination of “affects”. Therefore, it would be more appropriate to reference Council Strategy as the reason for the anticipated effluent limitation.” This

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comment was responded to in Response 2-5 of Appendix B, Response to Comments. The discharge is into an embayment that is at the west (upstream) end of Spring Lake. The embayment is separated from the Mississippi River by an island (See Figure 6 of the EAW, which can be found on our website at www.pca.mn.us). Measurements of flow by the Army Corps of Engineers (COE) show that flows enter the embayment through inlets above and below this island. In fact, the Army COE describes these inlets as inlets to Spring Lake. From the embayment, all of the water discharges into the main part of Spring Lake. Therefore, the discharge is deemed to be directly to Spring Lake and Minn. R. 7050.0211, subpart 1 applies.

33. The MPCA finds that the environmental review is adequate to address concerns relating to water

quality effects of phosphorus in the effluent discharge because potential impacts to water quality that are reasonably expected to occur from the proposed expansion of this facility have been considered by MPCA staff during the review process. Methods to prevent these impacts (a 1 mg/L effluent phosphorus limit) have been identified.

34. The MPCA finds that the project, as it is proposed, does not have the potential for significant

environmental effects based on the type, extent, and reversibility of environmental effects reasonably expected to occur as a result of its discharge of phosphorus in the effluent.

Cumulative Potential Effects of Related or Anticipated Future Projects 35. The second criterion that the MPCA must consider, when determining if a project has the potential

for significant environmental effects that are reasonably expected to occur, is the "cumulative potential effects of related or anticipated future projects," Minn. R. 4410.1700, subp. 7.B (1999). The MPCA findings with respect to this criterion are set forth below.

36. The EAW identified residential and other development enabled by the project as related future projects that could result in traffic congestion that could adversely impact air quality unless appropriate mitigation were provided. This issue was discussed in Findings 8, 9, 10, and 11. The residential development enabled by the project could also adversely impact surface water quality due to inadequate treatment and management of storm water runoff from increased impervious surface in that development. In the EAW, it was indicated that the storm water and wetland preservation ordinances were protective of water quality. Subsequent to the distribution of the EAW, the MPCA staff became aware of the apparent failure of these ordinances to prevent large-scale erosion, sedimentation, and inundation in the case of one large development. This issue is discussed at length in Findings 15, 16, 17, 18, 19, and 20.

37. Comments concerning cumulative impacts were received from the DNR and from DCS&WCS. The DNR noted that the city of Rosemount will be subject to the Phase II NPDES Storm Water Rule issued by US Environmental Protection Agency (EPA), and indicated that the DNR will be encouraging greater reliance upon infiltration-based methodologies to address increased runoff volumes that result from development-related impervious surface creation. The DCS&WCS expressed concern over the possible impacts of development enabled by the project on surface water quality and also on watershed hydrology, particularly on the volume of water entering nearby surface waters. They express a clear preference on practices that maintain the original hydrology and that rely on infiltration of storm water, and state that such practices should be provided in each development.

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38. Based on MPCA staff experience, available information on the project, including a June 25, 2001 letter received from the city of Rosemount (Attachment B), and information presented by the commentors, the MPCA does not reasonably expect significant cumulative effects from this project and related actions.

39. In considering the cumulative potential effects of related or anticipated future projects, the MPCA finds that the reasonably expected effects from this project will not be significant.

The Extent to Which the Environmental Effects Are Subject To Mitigation by Ongoing Public Regulatory Authority 40. The third criterion that the MPCA must consider, when determining if a project has the potential for

significant environmental effects that are reasonably expected to occur, is "the extent to which the environmental effects are subject to mitigation by ongoing public regulatory authority," Minn. R. 4410.1700, subp. 7.C (1999). The MPCA findings with respect to this criterion are set forth below.

41. The following permits or approvals will be required for the project:

Unit of Government Permit or Approval Required Status A. MPCA NPDES permit Application submitted The NPDES Permit establishes effluent limits (including phosphorus and interim mercury limits) and reporting requirements, as well as other appropriate conditions, to assure the facility is in compliance with water quality rules. B. MPCA Mercury Variance Application submitted The variance from the mercury water quality standard provides the conditions under which the facility is granted a variance. These conditions include a plan for returning to compliance with the standard. C. MPCA WWTP Construction Plans &

Specifications Review Plans and Specifications submitted

This review assures that the facility design is consistent with good engineering practice, and that the technology in question is being appropriately applied. D. City of Rosemount Building Permit Application submitted The city building permit is the means by which the city of Rosemount assures that the facility will comply with applicable codes, plans and ordinances.

In addition to the above permits, which apply to the proposed facility per se, the MPCA also routinely issues sewer extension permits, which normally are reviewed to assure that hydraulic capacity exists in the receiving wastewater interceptor systems and treatment facility. If necessary, the MPCA can include conditions in the sewer extension permit that pertain to storm water controls.

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42. The MPCA has prepared a draft NPDES permit which includes a 1 mg/L effluent phosphorus limit,

and a variance from the mercury effluent limit that includes interim limits and requirements to reduce mercury by source reduction. All potential significant environmental effects that are reasonably expected to occur will be mitigated under the requirements of this permit, the Plans and Specifications Review, and the City of Rosemount Building Permit.

43. The city of Rosemount also has regulatory authority over land development, which must be consistent with the City’s storm water and wetland preservation policies and plans.

44. The MPCA has regulatory authority over land development in that all construction that disturbs over 5 acres of vegetation is subject to the NPDES General Permit for Construction Storm Water. Recent enforcement action was taken against the developer that was responsible for the incident described in Findings 15, 16, 36, 37, and 38.

45. The MPCA finds that ongoing public regulatory authority will address any significant potential environmental effects that were identified as reasonably expected to occur.

The Extent to Which Environmental Effects can be Anticipated and Controlled as a Result of Other Available Environmental Studies Undertaken by Public Agencies or the Project Proposer, Including Other EISs. 46. The fourth criterion that the MPCA must consider is "the extent to which environmental effects can

be anticipated and controlled as a result of other available environmental studies undertaken by public agencies or the project proposer, including other EISs." Minn. R. 4410.1700, subp. 7.D (1999). The MPCA findings with respect to this criterion are set forth below.

47. MPCA staff, as part of the potential environmental impact analysis for the proposed Rosemount WWTP Interim Improvements facility, reviewed the following documents. This list is not intended to be exhaustive. The MPCA also relies on information provided by the project proposer, commentors, staff experience, and other available information.

A. The Rosemount WWTP Interim Improvements Design Report; B. The Rosemount WWTP Interim Improvements Project EAW; C. The Rosemount WWTP Interim Improvements Project Permit Application; D. Nondegradation Review: Rosemount WWTP Interim Improvements Project; E. Variance Request: Rosemount WWTP Interim Improvements Project (for mercury); F. The Rosemount WWTP Interim Improvements Project mercury variance application; G. The Rosemount WWTP Interim Improvements Project Response to Comments; and H. Letter from Mr. Thomas D. Burt, Rosemount City Administrator, to Eric Kilberg, dated June

25, 2001.

48. The staff of the MPCA has been issuing NPDES permits on behalf of the US EPA since the early 1970’s. It has developed substantial experience and expertise with regards to the effects of effluent discharge on receiving waters, and on anticipating, preventing, and mitigating those effects.

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49. There are no elements of the project that pose the potential for significant environmental effects that cannot be addressed in the project design and permit development processes, or by regional and local plans.

50. Based on the environmental review, previous environmental studies, and the MPCA staff expertise on similar projects, the MPCA finds that the environmental effects of the project that can reasonably be expected to occur can be anticipated and controlled.

CONCLUSIONS OF LAW

51. The MPCA has jurisdiction in determining the need for an EIS for this project. The EAW, the permit

development process, the facility planning process, responses prepared by MPCA staff in response to comments on the Rosemount WWTP Interim Improvements EAW, and the evidence in the record are adequate to support a reasoned decision regarding the potential significant environmental effects that are reasonably expected to occur from this project.

52. Areas where the potential for significant environmental effects may have existed have been identified

and appropriate mitigation measures have been incorporated into the project design and permits. The project is expected to comply with all MPCA standards.

53. Based on the criteria established in Minn. R. 4410.1700 (1999), there are no potential significant

environmental effects reasonably expected to occur from the project.

54. An EIS is not required.

55. Any findings that might properly be termed conclusions and any conclusions that might properly be termed findings are hereby adopted as such.

ORDER

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The MPCA determines that there are no potential significant environmental effects reasonably expected to occur from the Rosemount Wastewater Treatment Plant Interim Improvements project and that there is no need for an Environmental Impact Statement.

IT IS SO ORDERED

__________________________________________ Karen A. Studders, Commissioner Minnesota Pollution Control Agency __________________________________________ Date

APPENDIX B

Minnesota Pollution Control Agency

Rosemount Wastewater Treatment Plant Interim Improvements Environmental Assessment Worksheet (EAW)

RESPONSES TO COMMENTS ON THE EAW

Comments by Sharon Anderson, Transportation Planner/Local Government Liaison, Minnesota Department of Transportation, letter dated February 15, 2001 Comment 1-1: “We find the assessment acceptable, as it should have little or no impact to the State Highway System or its right of way.” Response 1-1: Comment Noted. No response is required. Comment 1-2: “This letter represents only the transportation concerns of Mn/DOT Metro Division. Additional environmental concerns raised by a wider Mn/DOT review may be forwarded to you in a separate letter.” Response 1-2: Comment Noted. No additional comments were received as of May 7, 2001. Comments by Helen A. Boyer, Director, Environmental Services Division, Metropolitan Council, letter dated March 5, 2001 Comment 2-1: Comments on Matters of Regional Concern “The proposed interim improvements are intended to serve planned growth in the City of Rosemount through 2005, when a different treatment option will be in place to serve the longer term needs of the area. Council staff have reviewed this EAW to determine its adequacy and accuracy in addressing regional concerns and potential environmental impacts. The EAW is complete and accurate with respect to these broad regional concerns.” Response 2-1: Comment noted. No response is required. Comment 2-2: Item 12. Page 5. Errata Sheet. Physical Impact on Water Resources. “The information we provided to you for preparation of the EAW states that the Rosemount Plant discharges into the Mississippi River at river mile UM 823.2, not at UM 823.5 as indicated in this item of the EAW. As a result, the plant does not discharge directly to Spring Lake.” Response 2-2: Attachment A to this Response to Comments is a copy of the Figure 6 of the EAW, showing the outfall location. Since river miles are measured at the channel centerline, it is difficult to equate a position on the shore, over one-half mile away, with a river mile. In any event, the outfall is located in an embayment located at the west (upstream) end of Spring Lake. The embayment is not hydraulically isolated from the Mississippi River or from Spring Lake. According to flow measurements taken by the US Army Corps of Engineers, inflows to Spring Lake occurred at inlets located at U.M. 823.2, 822.7 and 821.8. The first two locations are the entrances from the Mississippi River to the embayment at the west end of Spring Lake, while the third and fourth locations are direct inlets to Spring Lake. Since no flow leaves the embayment except by way of Spring Lake, and the effluent is discharged into the embayment, all of the effluent from the Rosemount Facility will enter Spring Lake. Historically, the MPCA staff has always contended that the facility discharges to a lake. Attachment B to this Response to Comments is an internal MPCA memorandum dated May 15, 1986, from John F. McGuire, Section Chief of the Monitoring and Analysis Section to Curtis J. Sparks, Chief of the

Rosemount Wastewater Treatment Plant Interim Improvements Responses to Comments on the Rosemount, Minnesota Environmental Assessment Worksheet Permits Section. The memo addresses the question of whether a 1 milligram per liter (mg/L) effluent phosphorus limitation should be assigned to the proposed Rosemount aerated stabilization pond (the facility which will be improved by this project subject to this EAW). The second paragraph of the memo notes that “The existing plant discharges to a small bay at the extreme end of a body of water called Spring Lake.” and “The present facility [a physical chemical WWTP] was assigned a 1 mg/L phosphorus requirement based on Minnesota Rule Part 7050.0210, subpart 6,…” (This Rule was renumbered as Minnesota Rule Part 7050.0211, subpart 1a.) The memo went on to evaluate four alternative strategies, including one that allowed the proposers to proceed with the new facility without a phosphorus limitation on the assumption that the then-proposed Spring Lake restoration would include construction of a dike that would preclude effluent from the Rosemount discharge from reaching Spring Lake. The memo recommended that approach, indicating if the Spring Lake rehabilitation plan were abandoned, the MPCA could resort to one of the other alternatives. Comment 2-3: Item 18.b. Page 7. Errata Sheet. Water Quality. Wastewater. Phosphorus. “Minnesota Rule 7050.0211, subpart 1a. states the following: ‘Where the discharge of effluent is directly to or affects a lake or reservoir, phosphorus removal to one milligram per liter shall be required. The arithmetic mean shall not exceed the stated value in any calendar month.’ ” “As stated above, the information we provided to you for preparation of the EAW states that the Rosemount Plant discharges into the Mississippi River at river mile UM 823.2, not at UM 823.5 as indicated in this item of the EAW. As a result, the plant does not discharge directly to Spring Lake. The discharge is more than ¼ mile upstream of the beginning of Spring Lake.” Response 2-3: See response to Comment 2-2, above. Comment 2-4: “The EAW item correctly points out that a significant amount of flow from the Mississippi River enters Spring Lake, even under low flow conditions (38%). Given the size of the plant discharge and phosphorus load in comparison to the river flow and load into the lake, it is difficult to imagine how the phosphorus in the facility discharge could “affect” Spring Lake, even if some of the effluent does enter the lake. We are not aware of any separate evaluation or study that MPCA has conducted on the impact or effect this discharge has on Spring Lake. Therefore, we do not know the basis under which MPCA staff have determined “affect,” and subsequently determined applicability of the rule. In addition, the previously issued NPDES permit did not make this determination and has not required phosphorus removal. As a result, Council staff strongly disagree that Minnesota Rule 7050.0211, subpart 1a. applies in this case and that it is not appropriate to cite that rule as the basis for an effluent phosphorus limitation in the NPDES permit. Response 2-4: Since the discharge is directly to Spring Lake, it is not required to demonstrate that the discharge affects a lake or reservoir. See also the response to Comment 2-2 and 2-3, above. Comment 2-5: Item 18.b. Page 7. Errata Sheet. Water Quality. Phosphorus. “Minnesota Rule 7050.0211, subpart 1a states the following: “Where the discharge of effluent is directly to or affects a lake or reservoir, phosphorus removal to one milligram per liter shall be required. The arithmetic mean shall not exceed the stated value in any calendar month.” “However, the Council recognizes the importance of phosphorus reductions from all sources to our surface waters. The Council adopted a Phosphorus Reduction Strategy in June 1997. This strategy established as a goal the addition of phosphorus removal facilities at all of our wastewater treatment plants at the time we construct capacity expansions. While we do not agree that this plant “discharge of

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Rosemount Wastewater Treatment Plant Interim Improvements Responses to Comments on the Rosemount, Minnesota Environmental Assessment Worksheet effluent is directly to or affects a lake or reservoir”, we have incorporated plans to remove phosphorus as part of this capacity expansion, consistent with our Phosphorus Reduction Strategy.” “As a result, we do not object to imposition of a phosphorus removal limitation of 1 mg/l since we are adding chemical precipitation facilities for phosphorus removal with this interim improvement. However, we do think that the agency’s determination of regulatory applicability is incorrectly derived and is not supported by a determination of “affects”. Therefore, it would be more appropriate to reference Council Strategy as the reason for the anticipated effluent limitation.” Response 2-5: The MPCA applauds the Council’s adoption of a Phosphorus Reduction Strategy. For the record, a one mg/L effluent phosphorus limitation is being assigned to the facility, just as it had been assigned to the predecessor physical-chemical treatment facility, because the facility discharges to Spring Lake. Comment 2-6: Item 18.b. Page 7. Errata Sheet. Water Quality. Wastewater. Mercury. “We have discussed the variance from the mercury limitation and are aware that MPCA staff intend to impose a mercury effluent limitation of 6.9 nanograms per liter (ng/l), effective at the end of the variance period. However, the EAW indicates that an “interim” mercury limitation, set at a “level currently achievable” will be established as a monthly average after one year of effluent monitoring. This has not been our understanding. We had understood that MCES would be required to implement a pollutant minimization plan and that there would be no applicable effluent limitation during the variance period. As a result of this misunderstanding, we will continue to discuss this matter during permit issuance.” Response 2-6: It is Environmental Protection Agency (EPA) policy that impaired waters not be further degraded, meaning that point source discharges, notably expansions, must assure that current discharge levels are not exceeded. By inserting an interim limit based on levels that are currently achievable, no increase occurs to the receiving water. While this provision is not found expressly written in Minn. R. ch. 7050, or Minn. R. ch.7001, variance provisions at Minn. R. 7000.7000, subp. 8, allow broad MPCA discretion in determining permit conditions. This is consistent with EPA policy, and it corresponds precisely to what is already currently in regulation in Minn. R. 7052.0280, subp. 5(A), for dischargers in the Lake Superior Basin. All mitigation measures, including permit effluent limits that were discussed in the EAW must be included in the National Pollutant Discharge Elimination System (NPDES) Permit. The MPCA made a Finding of Fact that the project does not have the potential for significant environmental effects, based on effluent limits described in the EAW. The MPCA cannot then issue an NPDES Permit that does not contain those effluent limits (or limits at least as restrictive as those described in the EAW). Such action would first require preparation of an amended EAW. If the Permittee is in disagreement with this or any other permit provision they should submit comments during the permit public notice period. The condition may well be negotiable, but removal of this condition would result in the preparation of an amended EAW and a delay in issuing the permit. Comments by Thomas W. Balcom, Supervisor, Environmental Review Section, Office of Management and Budget Services, Minnesota Department of Natural Resources, letter dated March 7, 2001. Comment 3-1 “Item 17a, in its discussion of storm water runoff management issues, indicates that review of the City of Rosemount’s storm water ordinances reveals that they “were found to be protective of water quality.” We take the opportunity to note that the City of Rosemount will be subject to the Phase

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Rosemount Wastewater Treatment Plant Interim Improvements Responses to Comments on the Rosemount, Minnesota Environmental Assessment Worksheet II NPDES Stormwater Rule issued by USEPA as it becomes operational over the next few years. As the Phase II process comes forward, DNR will be encouraging greater reliance upon infiltration-based methodologies to address increased runoff volumes that result from development-related impervious surface creation. We look forward to working with MPCA, local governments, consultants, and proposers as the opportunity arises.” Response 3-1: Comment noted. The MPCA agrees that infiltration-based storm-water management is preferable over solutions that involve treatment and conveyance. Comment 3-2: “Item 18b addresses the issue of ‘the technical and economic feasibility of providing treatment sufficient to meet the water quality based effluent limit (WQBEL) for mercury.’ DNR concurs with the MCES conclusions and the MPCA’s staff’s recommendation that a variance for mercury be granted ‘provided the permit contains mercury effluent limitations and pollutant minimization requirements.’ We believe that this and other facilities should be regulated to insure that mercury source reduction strategies are implemented in an expeditious yet timely manner. In this regard we recommend that the upcoming permit for the Rosemount WWTP contain a special condition that requires submission of MCES study results on the need for additional mercury treatment one year after initiation of operation of the updated facility. This timing allows for full consideration of available mercury control options for the next permit cycle (some 5 years hence). DNR will review the draft NPDES permit and variance when it becomes available at a later date.” Response 3-2: Metropolitan Council Environmental Services (MCES) must demonstrate further progress towards attaining the mercury water quality standard as a result of being granted this variance. The MPCA agrees that source reduction strategies are preferable to treatment strategies. If MCES finds that they can meet final effluent limitations within the term of this permit, a subsequent application for renewal of the variance would not be required. Should the MCES believe they would need to re-apply for a mercury variance in anticipation of the expiration date of the permit, they would be required to conduct a study. This study should include bench scale studies of additional treatment for total suspended solids that would cost-effectively remove mercury from the effluent. The study would be submitted with any request to re-new the variance at the time the permit application is submitted. Comment 3-3: “We take the opportunity to note that assignment of a 1 mg/l effluent phosphorus limit on a monthly basis is appropriate for this facility.” Response 3-3: Comment noted. No response is required. Comment 3-4: “Thank you for the opportunity to review this project. The project does not require preparation of an environmental impact statement (EIS) based upon natural resource considerations. Response 3-4: Comment noted. No response is required. Comments by Laura Jester, Watershed Conservationist, Dakota County Soil and Water Conservation District, letter dated March 7, 2001. Comment 4-1: “Under Item #16, Erosion and Sedimentation, it is indicated that silt fences and bale checks will be used to minimize construction erosion. However, bale checks do not provide adequate protection from erosion of exposed soils. In fact, they can often promote scouring and erosion around and under the bales. Please consider using silt fence checks or other means to control erosion on slopes.”

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Rosemount Wastewater Treatment Plant Interim Improvements Responses to Comments on the Rosemount, Minnesota Environmental Assessment Worksheet Response 4-1: The MPCA agrees with the observation, and in fact, this author is now advising project proposers to use rock check dams and heavy-duty large pore silt fences in lieu of hay bales. Comment 4-2: “Under Item #18, Water Quality – Wastewater, continuously exceeding the WQBEL for mercury may be problematic in the future for organisms in Spring Lake and the Mississippi River. We urge the Metropolitan Council to continuously explore ways to reduce the mercury levels both in the influent and the effluent of the WWTP.” Response 4-2: Because the analysis on the samples taken showed that the facility could not meet the water quality standard, MCES submitted a variance request in accordance with Minn. R. 7050.0190 and 7000.7000. The variance request included information on costs of two treatment technologies, neither of which guarantees that the WQBEL will be met. MCES also provided information on various mercury reduction efforts that are also being implemented. The cost evaluations and mercury reduction efforts are sufficient to demonstrate that end of pipe treatment is not the cost-effective route to controlling mercury. The MPCA staff has determined that the variance application is complete and recommends that the variance be granted. This variance is applicable for the duration of this permit. If the permit is reissued, the variance request must be applied for again. Consequently, the MCES is required to explore ways to reduce mercury levels in the plant influent.

Comment 4-3: The Dakota County Soil & Water Conservation District also expressed concern over the possible impacts of development enabled by the project on surface water quality and also on watershed hydrology, particularly on the volume of water entering nearby surface waters. They express a clear preference on practices that maintain the original hydrology and that rely on infiltration of stormwater, and state that such practices should be provided in each development. Response 4-3: The MPCA agrees with the District and forwards the comment on to the city of Rosemount. Comments by Lynn Moratzka, Director, Dakota County Office of Planning, letter dated March 9, 2001 Comment 5-1: In question 19.b. (page 10) the soil classifications and granularity on the site are given, but the rest of the question regarding the potential for groundwater contamination from wastes or chemicals spread or spilled onto the soils, and any other proposed mitigation measures are missing from the response. A response to this part of question 19.b. should be added. Response 5-1: See Errata Sheet No. 2. Comment 5-2: “The Response to question 29 (pages 13 and 14 could be clearer regarding the current watershed management situation. County staff suggests the following clarifications:” Response 5-2: See Errata Sheet No. 2.

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Rosemount Wastewater Treatment Plant Interim Improvements Responses to Comments on the Rosemount, Minnesota Environmental Assessment Worksheet

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Comments by Britta L. Bloomberg, Deputy State Historic Preservation Officer, Minnesota Historical Society, letter dated March 12, 2001 Comment 6-1: “There are no properties listed on the National or State Registers of Historic Places, and no known or suspected archaeological properties in the area that will be affected by this project. Therefore, in our opinion, the “no” response to question 25a is appropriate. Response 6-1: Comment noted. No response is required.

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