STATE OF MINNESOTA MINNESOTA POLLUTION CONTROL AGENCY FINDINGS OF FACT

Transcription

1 STATE OF MINNESOTA MINNESOTA POLLUTION CONTROL AGENCY IN THE MATTER OF THE DECISION ON THE NEED FOR AN ENVIRONMENTAL IMPACT STATEMENT FOR THE PROPOSED LONSDALE WASTEWATER TREATMENT FACILITY EXPANSION, RICE COUNTY LONSDALE, MINNESOTA FINDINGS OF FACT CONCLUSIONS OF LAW AND ORDER FINDINGS OF FACT Pursuant to Minn. R (2001), 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,, and Order: FACILITY HISTORY Overview The city of Lonsdale (City) is proposing to construct a new mechanical wastewater treatment facility (WWTF) to replace the existing stabilization pond and aerated pond facilities. The new WWTF will be constructed in the location of the existing pond facilities and will increase the design capacity from 241,800 gallons per day (gpd) to 687,000 gpd during Phase I and to 987,000 gpd at Phase II. Permitting History The City s WWTF was originally permitted for construction of the two stabilization pond cells in 1972 and expanded in 1987 with the addition of two aerated pond cells. The existing WWTF has been operating under a National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) Permit that was issued on May 12, Compliance/Enforcement History The existing WWTF has experienced occasional exceedances of assigned effluent limitations for the fiveday carbonaceous biochemical oxygen demand and total suspended solids. Also, during the summer of 2000, the MPCA staff received complaints about odors from the existing WWTF. The exceedances of these effluent limits and the odor problems were addressed through changes in operation of the WWTF and no formal enforcement action was taken by MPCA staff. Therefore, no past compliance issues will affect the proposed project. TDD (for hearing and speech impaired only): (651) Printed on recycled paper containing at least 30% fibers from paper recycled by consumers

2 PROPOSED PROJECT DESCRIPTION Proposed Construction/Proposed Modification The WWTF upgrade and expansion would be implemented in two phases. In the first phase, the treatment capacity will increase from the existing 241,800 gpd to 687,000 gpd. The existing secondary aerated pond cell will be converted into two extended aeration basins. The existing two stabilization pond cells and the primary aerated pond cell will operate during construction of the new WWTF and will be abandoned after construction is completed. The Phase I expansion will consist of new preliminary wastewater treatment including screening, grit removal and Parshall flume for influent flow measurement, a flow mixing tank, the two extended aeration basins with air supply system, an intermediate pump station, two final clarifiers with covers, a chemical addition system for phosphorus removal, an ultraviolet (UV) disinfection unit, an aerobic sludge digester/storage tank with cover, a control building, and a standby electric generator. The treated wastewater will be discharged in a continuous discharge mode through the existing outfall pipe currently used for the aerated pond discharge. The Phase II construction will most likely take place sometime between 2008 and 2015, depending on the City s growth rates. For the Phase II expansion to 987,000 gpd, the operating level in the extended aeration basin will be increased to accommodate the additional volume and include the installation of additional aeration equipment. Additional UV modules will be added for disinfection of the higher flow and an additional biosolids storage tank will be provided. Environmental Concerns The following environmental concerns associated with the proposed expansion of the WWTF were identified and addressed in the EAW: Potential for noise and dust during the construction phase; Storm-water runoff and erosion and sedimentation during construction; Potential for odors from the WWTF; Impacts of the discharge of treated wastewater on water quality; and Cumulative impacts from secondary development. Permitting Requirements Required permits and approvals are listed in Paragraph 23 below. Construction for the proposed project will not start until all permits and approvals are issued. These permits and approvals will mandate that the WWTF operate in compliance with all applicable regulatory requirements. 2

3 PROCEDURAL HISTORY 1. Pursuant to Minn. R , subp. 18.B., an EAW was prepared by MPCA staff on the proposed project. Pursuant to Minn. R (2001), the EAW was distributed to the Environmental Quality Board (EQB) mailing list and other interested parties on March 28, 2003, and is hereby incorporated by reference. 2. The MPCA notified the public of the availability of the EAW for public comment. A news release was provided to interested parties on April 3, In addition, the EAW was published in the EQB Monitor on March 31, 2003, and available for review on the MPCA Web site at on April 3, The public comment period for the EAW began on March 31, 2003, and ended on April 30, During the 30-day comment period the MPCA received two comment letters from government agencies and received no comment letters from citizens. The MPCA received a comment letter from the Minnesota Department of Natural Resources and a comment letter from the Minnesota Historical Society/State Historic Preservation Office. 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 as Appendix A to these findings. The MPCA responses to comments received are hereby incorporated by reference as Appendix B to these findings. CRITERIA FOR DETERMINING THE POTENTIAL FOR SIGNIFICANT ENVIRONMENTAL EFFECTS 5. Under Minn. R , subp. 1 (2001), 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 , subp. 7 (2001). These criteria are: A. the type, extent, and reversibility of environmental effects; 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. 3

4 THE MPCA FINDINGS WITH RESPECT TO EACH OF THESE CRITERIA ARE SET FORTH BELOW Type, Extent, and Reversibility of Environmental Effects 6. 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 , subp. 7.A (2001). The MPCA findings with respect to each of these factors are set forth below. 7. Reasonably expected environmental effects of this project to air quality: A. Odors; B. Noise; and C. Dust. 8. The extent of any potential air quality effects that are reasonably expected to occur: A. Odors The City and the MPCA have received complaints about odors from the existing WWTF in the past. Odors from the existing stabilization ponds are typically experienced during spring thaw conditions. Complaints about odors were received during the summer of 2000 when the aerators for the aerated pond were turned off. Odors are a concern due to the proximity of the WWTF to residential areas, currently located approximately 1,200 feet away. Residential development plans indicate that future homes may be located feet away from the WWTF. The proposed upgraded WWTF will eliminate both the stabilization pond system and the aerated pond system. The extended aeration basins will have duplicate process units and multiple aerators to prevent the potential for odor problems. The aerobic digester will be aerated and covered. The preliminary treatment (screenings and grit removal) will be enclosed in a building to minimize odors from this process. Therefore, the design improvements of the new WWTF are expected to reduce the potential for odor impacts and are not expected to result in more problems with odors than the existing WWTF. B. Noise Noise will be generated by heavy equipment and truck traffic during construction of the new WWTF. To minimize the impacts, the equipment will typically be operated only during daylight hours. In a WWTF, large horsepower blowers are usually responsible for emitting noise. For the proposed project, the blowers will be enclosed by sound enclosures and placed inside a concrete building. Therefore, no significant long term impacts from noise are expected from the proposed project. 4

5 C. Dust Dust may be generated during construction from truck traffic and from construction activities at the project site, depending upon weather conditions. This can be mitigated through the use of water, as needed, to minimize the dust. As a result, dust should not pose a significant environmental effect within the community during construction of the new WWTF. 9. The reversibility of any potential air quality effects that are reasonably expected to occur: The MPCA finds that any potential effect that is reasonably likely to occur from this project would be reversible. As discussed above, the expected effects on air quality are minimal. There is no reason to believe that this project is reasonably expected to cause a significant negative effect on air quality. 10. The MPCA finds that the environmental review is adequate to address the concerns because: All potential impacts to air quality that are reasonably expected to occur from the proposed project have been considered during the review process and methods to prevent these impacts have been developed. 11. 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 air emissions. 12. Reasonably expected environmental effects of this project to water quality: A. Surface-water Runoff B. Water Quality Impacts to Receiving Waters 13. The extent of any potential water quality effects that are reasonably expected to occur: A. Surface-water Runoff Runoff from the site of the project is likely to increase for a period of time during reclamation of the existing pond cells. After the reclamation, the land will be covered with top soil and seeded for erosion control. The City is required to obtain a NPDES Storm Water Permit for Construction Activity prior to commencing any land disturbing activities. The permit specifically requires implementation of best management practice measures to control erosion and sedimentation during construction. After construction is completed, the quantity and quality of surface-water runoff should be similar to current conditions and may be an improvement over existing conditions. The City will take precautions to protect a wetland located south of the WWTF s property boundary. A silt fence will be placed along the north edge of the wetland to capture any silt runoff from the construction site. 5

6 B. Water Quality Impacts to Receiving Waters The type of wastewater received by the WWTF is mainly from residential sources. Commercial and industrial users contribute less than five percent of the current wastewater flow. The City has allocated seven percent of future wastewater capacity for commercial activities and five percent to industrial users. The new mechanical WWTF will discharge to the same unnamed ditch currently used by the existing WWTF and is classified as a Class 7 limited resource value water. The classification of the unnamed ditch changes to a Class 2B water approximately 0.8 miles downstream of the discharge point. The effluent limits that will be assigned to the new mechanical WWTF through the proposed NPDES/SDS Permit are protective of the water quality use classifications of the receiving waters and therefore will minimize the impact to these waters. Proposed permit limits include a phosphorus limit of 1.0 milligrams per liter (mg/l) as a monthly average. The existing WWTF does not provide treatment for phosphorus and is not required to meet a phosphorus limit. Seasonal ammonia limits will be imposed upon completion of construction of the Phase II expansion. The Phase I facility will be designed to treat for ammonia and will be capable of ammonia removal. The proposed permit will require the City to monitor the receiving waters after completion of construction of the Phase I expansion to determine the impact of unionized ammonia levels in the stream from the discharge and insure protection of the higher quality waters downstream. The site specific data collected during this Phase I permit cycle will also be used to more accurately determine the appropriate seasonal ammonia limits for the permit issued at the Phase II expansion. 14. The reversibility of any potential water quality effects that are reasonably expected to occur: The MPCA finds that any potential effect that is reasonably likely to occur from this project would be reversible. As discussed above, the expected effects on water quality are minimal and the permit will require additional monitoring for ammonia to insure protection of the higher quality waters downstream of the discharge. There is no reason to believe that this project is reasonably expected to cause a significant adverse effect on water quality. 15. Comments received that expressed concerns regarding potential effects to water quality: Comments concerning potential impacts to water quality were received from the Minnesota Department of Natural Resources (DNR). DNR staff from the Division of Fisheries expressed concern for the current and future status of Union Lake and its fishery located approximately seven miles downstream from the WWTF discharge point. The DNR comment letter asked how the expanded discharges associated with both phases of the WWTF expansion would affect the mass loading of phosphorus in the effluent. The existing WWTF does not provide treatment for phosphorus. Phosphorus monitoring indicates that influent concentrations of phosphorus range between 5 6 mg/l. The WWTF currently discharges an average of 4 mg/l or 8.1 pounds per day (lbs/day) of phosphorus. At current design flow conditions, the existing WWTF is permitted to discharge a mass loading of up to 2,947 pounds 6

7 per year (lbs/yr). During the Phase I and Phase II expansions the WWTF will be required to meet an effluent limit of 1.0 mg/l as a monthly average. With the 1.0 mg/l phosphorus limitation, the Phase I facility would be permitted to discharge no greater than 5.7 lbs/day, for a total of 2,091 lbs/year, and the Phase II facility would be permitted to discharge no more than 8.2 lbs/day, for a total of 3,005 lbs/year. Therefore, after the Phase I expansion, the current phosphorus loading will be reduced approximately 30 percent from existing conditions. If the Phase II expansion occurs, the maximum phosphorus load will be held to approximately the same level as the current WWTF, even though the Phase II flow is more than four times that of the current design flow. As discussed above in Findings 13, 14, and 15, the analysis indicates that the effects on water quality that are reasonably expected to occur are not significant. 16. The MPCA finds that the environmental review is adequate to address the concerns because: All potential impacts to water quality that are reasonably expected to occur from the proposed expansion of this WWTF have been considered during the review process and a method to prevent these impacts has been developed. 17. 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. Cumulative Potential Effects of Related or Anticipated Future Projects 18. 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 , subp. 7.B (2001). The MPCA findings with respect to this criterion are set forth below. 19. The EAW discussed the potential for cumulative impacts from the proposed project. Phase I of the proposed expansion is needed to keep up with the City s current growth rate of homes per year. The Phase II expansion is expected to occur sometime between 2008 and 2015, depending on whether rapid growth rates will continue. A. Secondary Development The availability of an expanded wastewater service area will encourage additional development in the City. An increase in development would result in an increase in traffic, air pollution, storm-water runoff, the generation of solid waste, and result in the reduction of the open space and wildlife habitat in the area. Given the rapid pace of change in the area, the City will need to regularly assess and address impacts that occur due to secondary development. Enforcement of local, state, and federal ordinances, regulations, and permit terms and conditions will mitigate the potential environmental impacts from secondary development. 7

8 B. Storm-water Runoff As a result of growth and development within the City, there will be an increase in stormwater runoff. As pervious surfaces are increasingly replaced by impervious surfaces, the velocity and amplitude of runoff during storm events and snowmelts will increase causing the potential for degradation of local wetlands and receiving waters. The City is developing a process to put in place practices that will minimize the ongoing, long-term potential impacts from growth and development by authorizing the City Engineer to complete a Storm Water Management Plan. 20. Based on MPCA staff experience, available information on the project, including the EAW, the NPDES/SDS Permit application, and information presented by the commentors, the MPCA does not reasonably expect significant cumulative effects from this project. 21. 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 22. 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 , subp. 7.C (2001). The MPCA findings with respect to this criterion are set forth below. 23. The following permits or approvals will be required for the project: Unit of Government Permit or Approval Required Status A. MPCA Facility Plan and Amendment No.1 Approved B. MPCA NPDES/SDS Discharge Permit Application submitted C. MPCA NPDES Construction Storm Water Application to be submitted General Permit D. MPCA Plans and Specifications for construction of Phase I WWTF To be submitted 24. A. MPCA Facility Plan Approval The Facility Plan review and approval is performed to insure that the proposed WWTF meets minimum engineering standards. B. NPDES/SDS Discharge Permit An NPDES/SDS Permit will be prepared and issued by the MPCA following a 30-day public notice comment period. The NPDES/SDS Permit authorizes a maximum discharge flow and pollutant loading discharged from the WWTF. Effluent limitations established within the permit insure that the water quality standards and uses of the receiving water are protected. 8

9 C. NPDES Construction Storm Water Permit A Construction Storm Water General Permit is required when construction activity disturbs five or more acres of land. The permit sets forth requirements for preventing storm-water runoff, erosion, and sedimentation during construction of the WWTF. D. Plans and Specifications Approval Construction Plans and Specifications for the project are submitted to the MPCA for technical review and approval. This review is performed to insure that the WWTF design is consistent with good engineering practice and state and federal criteria. 25. 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. 26. 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 , subp. 7.D (2001). The MPCA findings with respect to this criterion are set forth below. 27. The following documents were reviewed by MPCA staff as part of the potential environmental impact analysis for the proposed expansion of the Lonsdale wastewater treatment facility. 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. EAW data; Facility Plan and Amendment No. 1; NPDES/SDS Permit Application; and Effluent Limitations Summary form, Effluent Limit Review Checklist and supporting documents. 28. 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. 29. Based on the environmental review, previous environmental studies, and MPCA staff expertise on similar projects, the MPCA finds that the environmental effects of the project that are reasonably expected to occur can be anticipated and controlled. 9

10 CONCLUSIONS OF LAW 30. 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 Lonsdale Wastewater Treatment Facility Expansion 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. 31. 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. 32. Based on the criteria established in Minn. R (2001), there are no potential significant environmental effects reasonably expected to occur from the project. 33. An EIS is not required. 34. Any findings that might properly be termed conclusions and any conclusions that might properly be termed findings are hereby adopted as such. ORDER The Minnesota Pollution Control Agency determines that there are no potential significant environmental effects reasonably expected to occur from the Lonsdale Wastewater Treatment Facility Expansion project and that there is no need for an Environmental Impact Statement. IT IS SO ORDERED Sheryl A. Corrigan, Commissioner Minnesota Pollution Control Agency Date 10

11 APPENDIX B Minnesota Pollution Control Agency Lonsdale Wastewater Treatment Facility Expansion Environmental Assessment Worksheet (EAW) SUMMARY OF COMMENTS AND RESPONSES TO COMMENTS ON THE EAW 1. Minnesota Department of Natural Resources (DNR). Letter dated April 30, Comment 1-1: Ecological Services Division staff appreciated the opportunity to review a draft version of the EAW and discuss the principal issues of concern which centered on growth related increases in ammonia and phosphorus in the discharge and storm-water runoff. Staff was aware that the city of Lonsdale would receive a 1 mg/l phosphorus effluent limitation and that this requirement represented the usual regulatory response when phosphorus is determined to be a concern for receiving waters. Response 1-1: The comment is noted. Comment 1-2: Division of Fisheries staff have expressed concern for the current and future status of Union Lake and its fishery. The DNR would like to know how the expanded discharges associated with both phases of the WWTF expansion would affect phosphorus loads in the effluent. Response 1-2: The existing stabilization pond/aerated pond facility does not treat for phosphorus and has no effluent limit assigned for phosphorus. Phosphorus monitoring conducted by the city of Lonsdale (City) indicates that the effluent from the existing Lonsdale Wastewater Treatment Facility (WWTF) expansion averages about 4 milligrams per liter (mg/l). The Phase I and Phase II facilities will be required to meet a concentration limit of 1.0 mg/l as a monthly average. The following table illustrates the total design loadings for the existing WWTF, the Phase I expansion, and the Phase II expansion. Phosphorous Loadings City of Lonsdale Wastewater Treatment Facility (WWTF) Existing Permit Conditions Phase I Upgrade Conditions Phase II Upgrade Conditions Design Flow, mgd Phosphorous, mg/l Phosphorous Loading, lbs/day Phosphorous Loading, lbs/year million gallons per day (mgd)

12 Responses to Comments on the Environmental Assessment Worksheet As the table above illustrates, due to the 1.0 mg/l limitation for phosphorus, the Phase I phosphorus loadings at maximum design flow will be approximately 30 percent of that discharged from the existing WWTF. The maximum phosphorus loads for Phase II would be approximately equal to that of the existing WWTF even though the design flow would be more than four times greater. The phosphorus loadings for Phase I and II will likely be less than the values listed in the above table because the City will need to consistently treat to a phosphorus concentration less than 1.0 mg/l to ensure the limit is met. Comment 1-3: DNR staff would like to know if the current pond system, which is to be abandoned, could be modified to a vegetated wetland for further phosphorus removal. Response 1-3: The City has the option of keeping the existing ponds as part of the treatment system if they choose to do so. However, converting the existing ponds into a constructed wetland system would be costly. Environmental standards require removal of the sludge from the ponds and the installation of a synthetic liner, sands, and wetland media which would not only substantially increase the construction costs but the operation and maintenance costs as well. The MPCA does not support this alternative as a cost effective long-term solution for further phosphorus removal. The wetland may provide additional phosphorus removal for a period of time, but its effectiveness would diminish over time as the plants die, decompose, and release phosphorus back into the water. Comment 1-4: Currently, Union Lake is characterized as hypereutrophic and state resource agencies have responsibilities to address this and future potential impairment to both downstream resources. For that reason, we suggest inclusion of Union Lake in the MPCA Lake Assessment Program. Water Quality evaluation, modeling and goal setting would help inform Basin Planning Clean Water Partnership, NPDES permitting and other watershed improvement strategies needed to improve the deteriorated condition of Union Lake. Response 1-4: The comment is noted and has been forwarded to the appropriate MPCA staff. However, funding for the Lake Water Quality Assessment and Clean Water Partnership programs is very competitive and limited. 2. Minnesota Historical Society. Letter dated May 2, Comment 2-1: Question 25.a. of the EAW indicates that there are two properties in the general area of the proposed project that are listed on the National Register of Historic Places. It does not appear that either of these properties will be affected. Further, we do not feel that the project area has significant probability of including archaeological sites, and do not recommend a survey. Response 2-1: The comment is noted. Comment 2-2: Please note that this comment letter does not address the requirements of Section 106 of the National Historic Preservation Act of 1966 and 36 CFR 800, Procedures of the Advisory Council on Historic Preservation for the protection of historic properties. If this project is considered for federal assistance, or requires a federal permit or license, it should be submitted to our office with reference to the assisting federal agency. Response 2-2: The comment is noted and has been forwarded to the City. 2