ENVIRONMENTAL ASSESSMENT WORKSHEET

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2 ENVIRONMENTAL ASSESSMENT WORKSHEET Note to reviewers: The Environmental Assessment Worksheet (EAW) provides information about a project that may have the potential for significant environmental effects. This EAW was prepared by the Minnesota Pollution Control Agency (MPCA), acting as the Responsible Governmental Unit (RGU), to determine whether an Environmental Impact Statement (EIS) should be prepared. The project proposer supplied reasonably accessible data for, but did not complete the final worksheet. Comments on the EAW must be submitted to the MPCA during the 30-day comment period which begins with notice of the availability of the EAW in the Minnesota Environmental Quality Board (EQB) Monitor. Comments on the EAW should address the accuracy and completeness of information, potential impacts that are reasonably expected to occur that warrant further investigation, and the need for an EIS. A copy of the EAW may be obtained from the MPCA by calling An electronic version of the completed EAW is available at the MPCA Web site 1. Project Title: Lyon County Sanitary Landfill Expansion 2. Proposer: Lyon County 3. RGU: Minnesota Pollution Control Agency Contact Person Paul Henriksen Contact Person Jessica Ebertz and Title Environmental Administrator and Title Project Manager Address Lyon County Public Works Address 520 Lafayette Road North 504 Fairground Road St. Paul, Minnesota Marshall, Minnesota Phone Phone Fax Fax Reason for EAW Preparation: EIS Scoping Mandatory EAW X Citizen Petition RGU Discretion Proposer Volunteered If EAW or EIS is mandatory give EQB rule category subpart number and name: Minn. R , subp. 17 Solid Waste 5. Project Location: County Lyon City/Twp Lyons 1/4 S ½ Section 9 Township 110N Range 42W TDD (for hearing and speech impaired only): Printed on recycled paper containing 30% fibers from paper recycled by consumers

3 List of Figures: Figure 1 Site Location Map Figure 2 Existing Site Conditions Figure 3 General Land Use and Features Figure 4 Phased Development Plan Figure 5 Final Closure Plan Figure 6 Landfill Cross Sections Figure 7 Landfill Cross Sections Figure 8 Initial 10-year Expansion Phase Figure 9 Design Details of Proposed Project Figure 10 Stormwater and Environmental Monitoring Plan Figure 11 Screening Berm Plan and Cross Section List of Attachments: Attachment A Correspondence from Lyon County Planning and Zoning Attachment B Correspondence from Minnesota Department of Natural Resources (DNR) Natural Heritage and Nongame Research Program Attachment C Ground Water Modeling Results Attachment D Correspondence from Minnesota State Historical Preservation Office Attachment E Correspondence from Minnesota Office of the State Archaeologist 6. Description: a. Provide a project summary of 50 words or less to be published in the EQB Monitor. Lyon County (Lyon County or County) is proposing an expansion of its existing municipal sanitary landfill. The proposed expansion of the Lyon County Sanitary Landfill (the Landfill) would increase the capacity of the Landfill by approximately 7,133,080 cubic yards, including waste and cover material, representing an additional 81 years of service life. The Landfill is used for waste disposal for residents and businesses of Lyon, Lac qui Parle, Lincoln, Pipestone, Redwood, Rock, and Yellow Medicine counties. 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 will cause physical manipulation of the environment or will 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 Landfill is located on 99 acres of land currently used for Landfill operations, within approximately 320 acres designated as Lyon County Solid Waste Management property, in Section 9 of Township 110 North, Range 42 West, of Lyons Township. The Landfill is located approximately three miles south of Lynd, Minnesota, on the west side of 200 th Avenue and east of State Highway 23. A site location map is presented as Figure 1. As of December 2006, approximately 2,233,519 cubic yards of municipal solid waste (MSW) and industrial waste, including cover materials, had been placed at the Landfill, leaving approximately 170,031 cubic yards of remaining permitted capacity. The Landfill currently receives approximately 47,062 tons of waste annually, corresponding to approximately 78,280 cubic yards of airspace (2007 estimates), and will run out of disposal space in mid-2008 if no expansion(s) are constructed. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 2 Worksheet

4 I. Background The Landfill has been permitted by the MPCA since December 1970 (Permit SW-23). MSW was deposited in unlined trenches from inception until 1993, when the MPCA modified and reissued Permit SW-23 to require lined fill areas. The 1993 permit modification resulted in closure of the existent 19-acre unlined disposal area on the west side of the property and construction of Phases 1 through 4 lined disposal areas to the east. These new lined cells were provided with leachate collection and were used for MSW disposal until The total authorized airspace capacity of the combined unlined and lined portions of the Landfill in the 1993 permit was 1,472,900 cubic yards. In 1997 and 1998, the final cover was installed for Phases 1 through 3 and portions of Phase 4. During this time, leachate recirculation laterals were installed across the Phase 4 disposal cell and a pilot leachate recirculation system was implemented. A French Drain was also installed along the northern and eastern boundaries of the expansion area to intercept and divert ground-water flow away from the Landfill. The French Drain has been used to lower the ground-water table under the Landfill and maintain a minimum separation distance to the liner of five feet. In 1998, the permit was modified again to allow construction of a three-acre Phase 5 disposal area and increase authorized disposal capacity to 1,665,700 cubic yards. In 2000, that capacity was increased again to 1,825,500 cubic yards, and a three-acre Phase 6 lined disposal area was authorized for use. The leachate recirculation system was put into operation in August The leachate collection system and French Drain were extended during construction of Phases 5 and 6. The permit was reissued again in December 2002, and the construction of the Phase 7 disposal cell was incorporated with this permit modification. This is the cell currently being used for waste disposal. The current maximum solid waste disposal capacity of the unlined and lined portions of the Landfill is 2,403,550 cubic yards including solid waste and cover. The present-day layout of the Landfill is presented as Figure 2. II. Proposed Project Lyon County proposes to increase the permitted capacity of its existing MSW Landfill by completing a vertical expansion over existing Phases 5-7 and developing the area southwest and west of the existing Landfill footprint. The proposed expansion extends beyond the current 99-acre Landfill permit limits, but remains within the 320 acres of Lyon County Solid Waste Management property. A map showing the boundaries of the Lyon County Solid Waste Management property and surrounding land use and features is presented as Figure 3. The Landfill expansion is proposed to occur in four phases Phase 8 through Phase 11. The proposed phased expansion plan is presented in Figure 4. The first expansion to be constructed will be Phase 8, a vertical expansion over existing Phases 5-7. The construction of Phase 8 will result in additional disposal capacity of approximately 100,980 cubic yards, corresponding to an extended service life of approximately one year. This will provide the County with immediate additional waste fill capacity to allow construction of the Phase 9 subgrade and liner system. Phase 9 will be a southerly horizontal expansion of approximately 12 acres, with a vertical expansion over the existing closed, unlined cell and the lined Phase 1. A liner system will be constructed in the new horizontal expansion footprint and over the final cover of the unlined cell to provide protection to underlying soil and ground water. The Phase 9 expansion will also require the excavation of a closed four-acre demolition debris landfill. Construction and demolition material from that area will be used as controlled fill to attain the appropriate grade and slope for the base of the vertical expansion. If unsuitable demolition debris is present that cannot be used as controlled fill, it will be transferred to the Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 3 Worksheet

5 permitted demolition debris landfill (MPCA Permit SW-501) located in Russell, Minnesota. The development of Phase 9 will result in an additional disposal capacity of approximately 2,513,000 cubic yards, corresponding to an extended service life of 29 years. Phase 9 waste disposal will start in the southern portion before extending northward over the closed unlined cell; Phase 9 will be developed in three stages: Phases 9A, 9B, and 9C (see Figure 4). Phase 10 will be a westerly extension of Phase 9. Construction of the Phase 10 expansion will provide approximately 2,070,900 cubic yards of disposal capacity, corresponding to an extended service life of 23 years. The final proposed expansion of the Landfill will be Phase 11, directly to the west of Phase 10. Construction of the Phase 11 expansion will result in additional disposal capacity of approximately 2,448,200 cubic yards, corresponding to an extended service life of 28 years. As summarized in Table 1 below, the total additional volume of waste and cover material disposal capacity for all proposed expansion phases is 7,133,080 cubic yards, representing approximately 81 years of operating life based on current and projected population and disposal rates of the service area. Table 1 Phased Expansion Summary Phase Surface Area Waste & Cover Volume Estimated Life Status of Disposal Area (acres) (cubic yards) (years) Unlined 19 1,068,300 Closed ,450 Closed ,700 Closed ,100 <1 Active ,980 1 Proposed ,513, Proposed ,070, Proposed ,448, Proposed Phases 8-11 Total ,133, Landfill Total 81 9,536,630 Notes: Waste & Cover Volumes include final cover volumes. Estimates are based on an annual waste growth rate of 0.2 percent and an airspace utilization factor of 1,200 pounds per cubic yard. III. Landfill Design Features Several features have been incorporated into existing portions of the Landfill to minimize the potential for environmental impacts. These features have been designed to comply with permit requirements. The proposed expansion cells will be equipped with these features as well. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 4 Worksheet

6 Waste Screening The first step taken to minimize the potential for environmental impacts, such as air or water contamination, is to limit and screen the types of waste that can enter the Landfill. Wastes accepted at the Landfill include commercial, municipal, and residential waste material. Some types of nonhazardous industrial material, such as coal ash, foundry waste, dry paint waste, and food waste, are allowed for disposal, but require special authorization from the County. Industrial waste deliveries are specifically tracked and documented by the County. Prohibited industrial waste includes empty pesticide containers that have not been triple washed-certified, waste containing polychlorinated biphenyls, spills of non-hazardous materials, rendering and slaughterhouse waste, wastes that could spontaneously combust or that could ignite other wastes because of high temperatures, fiberglass urethane, polyurethane and epoxy resin waste, electronic products containing a Cathode Ray Tube, and spent activated carbon filters. Truckloads with a significant amount of demolition debris are required by the Landfill to be delivered to a specified area near the on-site maintenance buildings. Haulers unload the demolition debris materials into a small concrete screening area where it is temporarily stored. Landfill operators periodically load the materials into transfer trucks for transport to the Rock County Demolition Landfill in Luverne, Minnesota. The Landfill does not accept hazardous waste, untreated sewage sludge, septic tank pumpings, infectious wastes, radioactive wastes, free liquids, or waste containing free liquids, as required under Minn. R , subp. 1. Landfill personnel identifying waste not acceptable for disposal will divert or transfer the material to the proper disposal or recycling facility. Landfill Liner System The proposed expansion areas will be lined with composite liners, which consist of low-permeability soil overlain by a high-density polyethylene (HDPE) geomembrane. Landfill liners are designed to prevent the migration of leachate which is liquid created from water percolating through refuse beyond the landfill boundaries, into surrounding soils and/or ground water. They also help prevent the migration of LFGs. The composite liner system to be used in the proposed expansion areas meets or exceeds MPCA requirements. In accordance with Minn. R , subp. 7, this composite liner system, in conjunction with the leachate collection system, has been designed to collect or reject at least 95 percent of the precipitation falling on the fill area. The liner system is expected to maintain its integrity through the Landfill's active life and the 30-year post-closure care period. To further control and protect ground water below and adjacent to the Landfill, a portion of the proposed expansion will be constructed with an inward gradient system (IGS) below the composite liner. A ground-water drainage layer below the clay barrier layer will work to divert ground water flowing upward from the subgrade. The ground water will be collected in perforated pipes within gravel drains and channeled to a sump. Collected ground water will discharge to surface water drainage ways or sedimentation basins around the Landfill. Because water quality within the IGS sumps will be monitored on a regular basis, the system can act as a detection and collection system for any groundwater contamination that may occur. If there are any exceedances of MPCA intervention limits, the discharge will be routed to the leachate treatment ponds. Intervention limits are a concentration of a substance which, if found to be exceeded in a sample of ground water, indicates possible ground-water pollution from a facility. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 5 Worksheet

7 During active Landfill operations, waste will be placed and compacted in two-foot lifts within cells averaging eight to ten feet high. The initial waste lift will be monitored for material that could potentially damage the liner. Unacceptable material will be placed in the previous cell or in the second lift. In summary, the proposed composite liner system over newly constructed subgrade consists of (described from finished grade downward): Drainage Layer. A 12-inch drainage layer will be constructed of permeable sand. This drainage material will protect the liner system from MSW fill and allow for movement of leachate to the collection sumps. The layer will be graded to a smooth, uniform foundation that is free of depressions. Large rocks and other extraneous materials that could puncture the underlying liner will be removed. Geomembrane. Sixty-millimeter unreinforced HDPE will be used because of its superior resistance to puncture, weathering and chemical attack. The geomembrane is anchored into a perimeter trench designed to support the geomembrane's weight during liner installation and prior to waste placement. Barrier Layer. Two feet of compacted low-permeability clay. The clay layer will be carefully prepared to remove any vegetative growth, debris, or abrasive material that could puncture the geomembrane. Geocomposite Drainage Layer. A geonet encased on both sides by geotextile fabric will be installed below the geomembrane and clay barrier to promote drainage of ground water and relieve pressure on the liner. Subgrade. In-place compacted material graded to minimum 2 to 5 percent bottom slopes (toward the leachate collection pipes) and 33 percent side slopes. These features are shown in Figure 9. The proposed composite liner system over the existing unlined cell consists of (described from finished grade downward): Drainage Layer. A 12-inch drainage layer constructed of permeable sand to protect the liner system and promote leachate drainage. Geomembrane. A 60-millimeter unreinforced HDPE geomembrane liner. Geosynthetic Clay Liner. A 0.23-inch low-permeability geosynthetic clay liner designed to provide an additional barrier to prevent leachate infiltration into underlying soils in case of geomembrane puncture or tear. Liner/Slope Stabilization Layer. A six-inch sand drainage layer with interlaced primary and secondary uniaxial geogrids. The geogrid system is designed to provide structural reinforcement to the liner system in the event of potential settlement of underlying waste within the closed unlined cell. This layer will also stabilize the liner in this area for slopes less than 15 percent. Fill Layer. Fill layer in Phase 9 to bring slopes to appropriate grade for leachate management. Barrier Layer. Existing two feet of compacted low-permeability clay cover for underlying unlined waste cell. Leachate Collection and Transmission The leachate collection system consists of drain material and perforated pipe above the liner system to remove any leachate that is produced in the Landfill. This serves to protect the integrity of the liner by Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 6 Worksheet

8 minimizing the liquid levels (hydraulic head) impinging on the liner system, thus reducing the potential for leakage. Minn. R , subp. 9 governs the design of leachate collection and leak detection systems. The design of the Landfill includes a stormwater system to prevent surface water run-on during active operations and a low-permeability final cover to reduce precipitation infiltration after closure. Together, these systems are intended to substantially reduce the amount of leachate that is produced after Landfill closure. The Landfill bottom is graded so that the drainage layer slopes toward the low point of the liner. Each perforated pipe is located at the bottom of the V-shaped cell, sloped at a minimum of one percent to match the Landfill base, and is surrounded by a gravel drain. The gravel drains also provide backup leachate collection capacity should clogging or a localized failure of one of the perforated collection pipes occur. The perforated pipe and gravel drain traverse the length of the cell to the sump at the low end of the cell. The proposed system includes an 18-inch diameter, HDPE perforated pipe positioned within each sump and within the gravel backfill. Each of these pipes, termed a side slope riser (SSR), angles up the side slope of the cell toward the perimeter of the Landfill into a leachate collection vault. Access to the SSR is provided within the vault located at the top of the side slope berm. This design eliminates the need for a pipe penetration through the liner system. A submersible pump will be set at the base of each SSR to transfer leachate from the sump to the vault. Each pump discharge line will enter a lateral to a HDPE leachate transmission main, which conveys the leachate by gravity to the leachate management system (LMS). A sample port will be provided for leachate monitoring of each cell, if necessary. The HDPE leachate transmission main is a double-walled pipe to ensure containment that runs at a minimum one percent slope to the LMS and has been sized to allow for gravity flow of expected maximum leachate volumes without increasing hydraulic head on the liner system to more than one foot. The inner pipe carries leachate from each of the vaults to the LMS; the outer pipe acts to contain leaks, should they occur, from the inner pipe. Leachate Management Leachate generated from the lined phases at the Landfill currently discharges into a 15,000-gallon underground, double-walled, fiberglass tank. A pilot leachate recirculation system begun in 2005 is currently in operation at the active Phase 7 fill area. This system pumps leachate back into the Landfill through laterals located within the waste area. Recirculation reduces the leachate volume and need for off-site treatment and disposal. Implementation of a full-scale leachate recirculation program within the proposed Landfill expansion areas is conditional upon MPCA approval. Following completion of the current pilot study, a final report providing results and recommendations for long-term leachate recirculation will be submitted to the MPCA for review. If the MPCA approves the proposed long-term leachate recirculation system, then the current system will be extended into the proposed expansion areas. The proposed LMS consists of the following elements: leachate collection, leak detection, recirculation, and ultimate disposal. If necessary, ultimate disposal may consist of hauling to either the Marshall Wastewater Treatment Plant (WWTP) or the Metropolitan Council Environmental Services (MCES) facility in St. Paul, which was the disposal method prior to implementation of the pilot leachate Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 7 Worksheet

9 recirculation project in The on-site 15,000-gallon leachate storage tank will continue to be used for leachate storage for Phases 1 through 8. Leachate generated within Phases 9 through 11 will be discharged into two new leachate storage ponds located south of the proposed Landfill expansion. These ponds will be designed to handle expected maximum leachate generation, recirculation and treatment capacities. The proposed leachate pretreatment ponds will have a primary liner system consisting of a 60- millimeter HDPE geomembrane and bentonite geosynthetic clay liner. Below this will be a secondary liner system consisting of another geomembrane with a geocomposite drainage layer (i.e., geonet) between the two liner systems. A perforated, 12-inch diameter, HDPE leak detection collection pipe is located beneath the pond between the geomembranes and is backfilled with drainage stone. The pipe, which transitions to a 12-inch diameter, solid wall HDPE pipe, extends up the sideslope between the primary and secondary liners, connecting to a 12-inch diameter standpipe located beyond the perimeter of the pond. Each standpipe has a dedicated pump that discharges any liquid back into the pond. The perimeter lip of each pond is raised a minimum of one foot above the surrounding ground surface to prevent run-on of surface water into the ponds. The secondary geomembrane liner will be approximately five feet above the high ground-water elevation. In 2006, a total of 1,183,519 gallons of leachate were collected and recirculated back into the existing waste cell. Leak Detection Systems In addition to intercepting ground water and preventing it from entering the Landfill or causing damage to the liner system, the proposed IGS acts as a leak detection system for the liner system. The proposed IGS consists of geonet composite running below the liner barrier layer parallel to the leachate collection pipe network and extending along the slope of the subgrade until it is above the high ground-water level. The base of the IGS will be constructed on top of the prepared subgrade. The IGS will drain to a sump, directly below the leachate collection sump, which will be backfilled with gravel. The clay portion of the liner system will then be constructed directly over the IGS. A perforated 12-inch diameter HDPE pipe will be installed at the base of the IGS within the gravel backfill. This pipe will transition to a solid 12-inch diameter HDPE leak detection standpipe which will extend up the southern sideslope, beneath the primary liner and adjacent to the SSR. The leak detection standpipe will also enter the SSR vault along the southern berm. A submersible pump will be set at the base of each leak detection standpipe to transfer liquid collected in the IGS to the surface water system or the LMS, depending on monitoring results. The discharge line from the pump will be 1.5-inch diameter stainless steel with a quick disconnect within the vault, where the discharge line will transition to 1.5-inch diameter HDPE. Each pump discharge line will discharge to the surface water system or enter a lateral to an HDPE leachate forcemain, which will convey the liquid to the LMS. A sample port will be provided for monitoring of each leak detection standpipe, as required by the monitoring plan. Leak detection is also incorporated into the liner design for the leachate pretreatment ponds. This leak detection system consists of a drainage net (geocomposite) underlying the primary containment system, and a secondary liner system beneath that. Leakage into the drainage net system will flow by gravity to a leak detection standpipe. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 8 Worksheet

10 Stormwater Controls Minn. R , subp. 5 (D-F) require the installation of stormwater controls at MSW landfills to contain run-off and control/limit run-on. Stormwater controls are necessary to limit leachate generation and surface water ponding during active filling and prevent it after closure. These controls will: 1) intercept precipitation falling on or near the active fill area and route it away from the refuse; 2) control run-off/run-on near support facilities such as the pretreatment ponds; and 3) intercept run-off from the low-permeability cover system after final closure. Run-off from active areas of the Landfill will be directed back into the working face as much as reasonably practicable. The current stormwater control system will be modified and expanded, utilizing a combination of berms, ditches and channels, terraces, and sedimentation basins to contain and control the run-off and limit associated environmental impacts. This is described in detail in Item 17. Cover Systems Minn. R , subp. 6 requires daily, intermediate and final cover systems to minimize infiltration of precipitation; control landfill gas (LFG) movement; prevent surface water ponding; reduce erosion, litter and dust; retain slope stability; reduce the effects of freeze-thaw; and maintain vegetative growth. The cover systems for the proposed expansions at the Landfill will include the following elements: Daily Cover During active Landfill operations, placement of clean soil or alternate material over compacted refuse reduces odors, litter, and vermin, and somewhat limits the amount of precipitation percolating through the refuse. Daily cover material will consist of on-site soils placed to a depth of at least six inches, or an approved alternative daily cover. Intermediate Cover Whenever a waste cell is not anticipated to receive additional overlying waste for at least 30 days, it is covered with an intermediate, rather than daily, cover system. Intermediate cover will be placed to a depth of 12 inches or greater to cover the underlying compacted refuse. The intermediate cover will be graded to prevent surface-water ponding and to further promote run-off and evaporation of any precipitation falling on the cell. Final Cover Once a portion of the Landfill reaches final grade with minimal settlement, construction of a lowpermeability final cover is the most effective way to minimize the production of leachate. The main function of the final cover is to reduce moisture infiltration, to enhance evapotranspiration and runoff, and to minimize gas emissions. As per Minn. R , subps. 6 and 7, the final cover system must be designed and constructed to contain or reject at least 90 percent of the precipitation falling on the system; the liner system, in combination with the cover system, must achieve an overall site efficiency of 98.5 percent collection or rejection and minimize the amount of leachate leaving the fill site to the soil and ground water below the site. The final cover system will have a minimum slope for the crown of 5 percent, and maximum side slopes of 33 percent. Terraces will be constructed for all slopes greater than 20 percent to control stormwater drainage, reduce the potential for erosion, and provide slope stability. The proposed final cover system consists of: Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 9 Worksheet

11 Soil Layer. A minimum 18-inch soil layer that includes 6 inches of topsoil to promote vegetative growth. The lower 12 inches act as a rooting zone to minimize root penetration into the drainage layer and to maximize the evapotranspiration potential, thus adding stability to the topsoil layer. Drainage Layer. Different drainage layers are proposed for the Landfill side slopes and crown. A. Side slopes Geocomposite: A geonet encased on both sides by geotextile fabric will be installed above the geomembrane on side slopes greater than 20 percent to protect the barrier layer and to promote lateral drainage of surface water above the geomembrane cover. An additional six inches of rooting zone material will be placed on the side slopes to meet the minimum overall final cover thickness requirements of the Minnesota Solid Waste Rules. B. Crown Sand: A 12-inch layer of sand will be placed on the crown for lateral drainage of surface water above the geomembrane cover. Geomembrane Barrier Layer. A 40-millimeter linear low density polyethylene geomembrane will be placed above the soil buffer layer. It is recommended because of its tear resistance when sustaining waste differential settlement. The geomembrane is anchored into the perimeter trench with the bottom liner HDPE. Buffer Layer. The six-inch soil buffer layer will be graded in one six-inch lift. Stones and sharp objects will be removed and the material will be free of organics and have less than five percent fines. The buffer layer provides a smooth, stable base for the geomembrane. Intermediate Cover Layer. A 12-inch intermediate cover foundation layer will allow for gas transmission upward to vent points and movement of leachate down the Landfill side slopes to the drainage layer of the liner system. This layer will be graded to a smooth, uniform foundation that is free of depressions. Large rocks and other extraneous materials will be removed. Gas Control and Monitoring Systems Decomposition of organic wastes in a landfill produces various gases - principally methane and carbon dioxide. LFG usually contains percent methane and percent carbon dioxide. Gas production is a serious concern because of the combustibility of methane at concentrations between 5 and 15 percent in air and the potential release of odorous and/or noxious emissions to the atmosphere. The gas produced by refuse decomposition within a landfill may escape either by vertical or lateral migration. Typically, the majority of gas produced by a landfill during active operations will exit through the cover soil; however, if this vertical path is sealed by frost, rain-saturated cover soil, or "capping" with a low-permeability final cover, there is a greater tendency toward lateral migration. Lateral migration of gas can be influenced by many physical and environmental factors, including: the presence of a liner; leachate and LFG collection systems; refuse depth below grade and its total thickness; the depth of the water table; stratification within the landfill due to lift construction and cover material placement; stratification of surrounding earth material (directional variations in permeability); the presence of low-permeability soils or surficial deposits around the perimeter of the landfill; gas production rates and pressures within the refuse; soil and refuse moisture content; and atmospheric pressures. As required under Minn. R , subp. 11, Lyon County proposes a plan that includes gas probe, building, and confined space LFG monitoring. The currently installed gas probes are shown on Figure 2. The probes will be monitored quarterly for methane and oxygen concentration. Site structures will be monitored monthly. The MPCA will be notified if methane concentrations exceed the lower explosive limit (LEL) at the property boundary or 25 percent LEL within site structures, indicating a potential explosive situation. During each monthly gas monitoring event, the LFG vents and Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 10 Worksheet

12 recirculation lateral cleanouts will also be measured for percent methane and oxygen as required by the recirculation pilot demonstration program. Gas monitoring results will be forwarded to the MPCA quarterly. Lyon County is also proposing a passive LFG venting system for the Landfill expansion. The venting plan for the western expansion phases consists of vertical vent wells placed assuming a 100-foot radius of influence and extending to within 15 feet of the Landfill liner system. The passive venting system is proposed until MSW tonnage triggers the federal guidelines for an active system (2.5 megagrams or 2.76 million tons). Through Phase 7, it is estimated that a total of 1.2 million tons of MSW will have been disposed of at the Landfill. It is estimated that the Landfill will reach the waste volume of 2.76 million tons in approximately the year The passive system is designed to be easily converted to an active system. Future gas monitoring data will be evaluated to assess the need for an upgrade to a standard active system with a header system, condensate removal, and an exhauster/flare complex. An LFG collection and control system design will be provided as required when emissions estimates or field information indicates that non-methane organic compound emissions exceed 50 tons/year, in accordance with the New Source Performance Standards. Ground Water and Surface Water Monitoring Systems The Landfill has an established environmental monitoring system in accordance with Minn. R , subps. 10 and 14 that includes ground water and surface water monitoring locations. Water samples are collected for laboratory analysis on a routine basis, as established in the facility permit, and reported to the MPCA. An annual report is submitted to the MPCA providing a summary and discussion of the results and recommendations for the facility. The report presents recent and long-term trends in concentrations of monitored constituents and water elevations. As the Landfill is expanded, existing monitoring wells may need to be abandoned and new wells installed to maintain the monitoring system in accordance with the solid waste rules. Monitoring wells sealed due to Landfill expansion will be replaced with new wells installed with the approved Landfill compliance boundary. The environmental monitoring system for the proposed expansion is shown in Figure 10. c. Explain the project purpose; if the project will be carried out by a governmental unit, explain the need for the project and identify its beneficiaries. The purpose of this project is to extend the life of the Landfill by approximately 81 years. The Landfill will continue to serve seven nearby counties, including Lyon County, to provide a long-term viable solid waste option for the region. The beneficiaries will include the residents and businesses of the seven counties using the Landfill for solid waste disposal. Minn. Stat. 115A.917 provides that no new capacity for disposal of mixed MSW may be permitted in counties outside the Metropolitan area without a Certificate of Need issued by the Commissioner of the MPCA. The MPCA must determine that additional disposal capacity is needed in the county. Further, the statute provides that the MPCA shall certify need only to the extent that there are no feasible and prudent alternatives to the additional disposal capacity, including waste reduction, source separation, and resource recovery that would minimize adverse impacts upon natural resources. MPCA staff review of the county s request for new MSW landfill capacity is under way. The staff s preliminary review indicates that there is no existing solid waste resource recovery facility available to counties in the Landfill s service area that would reduce the need for new MSW landfill capacity. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 11 Worksheet

13 Lyon County is part of the Southwest Regional Solid Waste Commission (SWRSWC), which, in the past year, has committed to developing and expanding recycling programs in the Southwest Region to attain the goal of 50 percent recycling. The seven counties served by the Landfill are part of the SWRSWC. Lyon County is utilizing several methods to help attain this goal: Recyclable materials are discouraged for drop-off at the Landfill. Persons with recyclable materials such as cardboard, plastic or glass containers, and aluminum cans are directed to the recycling areas in Marshall, Minnesota. White goods, tires, fluorescent bulbs and electronics are accepted and stored at the Landfill in designated areas for recycling. Contracted vendors collect these materials when contacted by the County. Lyon County also has solid waste staff available to assist customers and counties in identifying recyclables that can be removed from the waste stream. Lyon County, through the Great Minnesota Landfill Cleanup fees, provides a rebate of $5.00 per ton to the surrounding counties that dispose of solid waste at the Landfill. This rebate money helps fund recycling programs within each county. In 2006, Lyon County implemented single-stream curbside recycling. Single-stream recycling encourages participation because of the convenience of not having to separate various types of recyclable materials into individual containers. In addition to curbside recycling, Lyon County maintains 18 smaller recycling collection buildings in the city of Marshall and various townships. Annually, Lyon County holds a single-day, reduced-rate collection event for appliances, waste tires and electronics at the Landfill. Lyon County operates a permanent household hazardous waste facility that accepts fluorescent bulbs, latex and oil-based paints, stains, varnishes, wood preservatives, poisons, dioxins, pesticides, flammable products, acids, bases, organic peroxides, oxidizers, and mercury. Landfill revenues help fund the Lyon County, and other county, household hazardous waste programs. 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. At this time, there are no plans for future development of the Landfill beyond what is outlined in this EAW. 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 Landfill has been operated as a MSW landfill since 1971, under the MPCA Solid Waste Permit SW-23. A detailed summary of the past operation and development of the Landfill is given in Item 6.b. Environmental review was previously required under Minn. R for a proposed expansion of the Landfill in During the review process, violations of Minnesota water quality and wetland nondegradation rules were identified at the Landfill site. A brief outline of the review process, along with a summary of enforcement action that was taken in response to the violations, is presented here: Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 12 Worksheet

14 In March 1999, the County submitted information needed for the development of an EAW for a proposed expansion of the Landfill, which would involve construction of three new disposal cells. This information did not mention the existence of an approximately 6.3-acre wetland located on County property to the southeast of the Landfill, or that the proposed expansion would impact that wetland. On October 5, 1999, the MPCA published in the EQB Monitor a notice that the EAW was available for public review for the proposed expansion. It was upon receipt of a letter from the U.S. Army Corps of Engineers during the EAW public comment period, that the MPCA environmental review staff became aware of the existence of the aforementioned wetland, which would be impacted by the expansion, and informed the MPCA solid waste compliance staff. On December 17, 1999, the MPCA inspected the Landfill and observed that a contractor for the County was excavating and backfilling the wetland. The MPCA immediately requested that this activity stop and instituted an enforcement action against the County with a Notice of Violation in February The County later withdrew the EAW published in October After receiving a new application for expansion of the Landfill, on August 20, 2001, the MPCA placed on public notice an EAW for the proposed expansion, which still involved development of the wetland. This EAW described issues related to the development of the Landfill in the wetland area and the unresolved enforcement action. The MPCA and the County settled the enforcement action in January 2002 by signing a Stipulation Agreement in which the County agreed to modify its proposed permit application to incorporate a design that did not involve development of the wetland area. On May 17, 2002, the Commissioner of the MPCA determined that there were no potential significant environmental effects reasonably expected to incur from the proposed expansion which no longer involved development of the wetland - and that there was no need for an EIS. The final proposal involved the construction of the current active disposal cell, Phase Project Magnitude Data Total Project Area (acres) 320 or Length (miles) Number of Residential Units: Unattached 0 Attached 0 Maximum Units Per Building: NA Commercial/Industrial/Institutional Building Area (gross floor space): total square feet 8,400 Indicate area of specific uses (in square feet): Office 2,000 Manufacturing 0 Retail 0 Other Industrial 0 Warehouse 0 Institutional 0 Light Industrial 6,400 Agricultural 0 Other Commercial (specify) 0 Building height 1 story If over 2 stories, compare to heights of nearby buildings NA Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 13 Worksheet

15 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 Solid Waste Disposal Facility Permit Existing SW-23. Modification required for expansion. MPCA NPDES/SDS* General Permit for Discharge Required. of Stormwater during Construction Activities MPCA NPDES/SDS General Stormwater Permit for Industrial Activities MPCA Certificate of Need for Landfill Expansion Required. DNR Water Appropriation Permit for dewatering activities Existing. Modification required for expansion. Required if pumping more than 10,000 gallons per day or 1 million gallons per year. MCES Industrial Discharge Permit Existing. Modification required for expansion. Lyon County Solid Waste Permit Existing. Modification required for expansion. Lyon County Building/Construction Permit Required. Lyon County Conditional Use Permit Existing. Modification required for expansion. City of Marshall Wastewater Discharge Permit Existing. Modification required for expansion. *NPDES/SDS = National Pollutant Discharge Elimination System/State Disposal System 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. The Landfill is located on approximately 320 acres owned by Lyon County Solid Waste Management in Section 9, Township 110 North, Range 42 West, approximately three miles south of Lynd, Minnesota. A portion of the site has been operated as an MPCA-permitted sanitary landfill since Approximately 99 acres were used for landfill operations, including waste disposal (41 acres), soil borrow, stormwater and sedimentation control, access roads, and administration facilities. The proposed development will add another 47 acres to be used for landfill operations, 41 of which will be used for waste disposal. A land use map is presented as Figure 3. A 4.6-acre wetland is located immediately southeast of the existing Landfill. The wetland was classified in a Wetland Delineation Report completed in October 2005 by Graham Environmental Services, Inc., as saturated palustrine, emergent (PEMB) and seasonally flooded palustrine, emergent (PEMC), which equates to Type 2 inland fresh meadow and Type 3 inland shallow fresh meadow, respectively. The Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 14 Worksheet

16 National Wetlands Inventory does not map this wetland. Typical emergent and upland vegetation such as rush, narrow-leaved cattail, river bulrush, sedge, Kentucky bluegrass and quack grass exist within the delineated limits of the wetland. The intended beneficial uses of the wetland include maintaining biological diversity, erosion control, stormwater retention and stream sedimentation. Stormwater run-off from portions of the existing closed Landfill drain to sedimentation ponds that eventually drain to the wetland. Directly to the south of the existing Landfill is the 333-acre Black Rush Lake wetland. A 37-acre portion of the wetland extends onto County property and the County has granted an easement for this portion to the U.S. Fish and Wildlife Service (USFWS). The Black Rush Lake wetland is part of a larger Waterfowl Production Area (WPA). According to the USFWS, the WPA consists of approximately 973 acres of restored wetland and upland habitats, with 2 acres of Type 1 wetlands, 11 acres of Type 3 wetlands and 320 acres of Type 4 wetlands. Most of the wetlands were drained at one time and are now restored with water control structures. The easement portion of the Black Rush Lake wetland that lies within County property boundaries located north of County Road 59 is not part of the WPA. Black Rush Lake wetland is located within the Redwood River Watershed. The defined easement limits are approximately 50 feet from the 1,471-foot elevation. Wetland vegetation in the shallow wetlands is mostly grasses, sedges and rushes. The Type 3 and 4 wetlands have a predominance of cattail and bulrush. The uplands consist of 21 acres of oak savanna and 619 acres of tame grasslands and restored native grassland habitats. Several small areas of planted tree groves also exist. Eventually discharging to the Redwood River, the Black Rush Lake wetland plays an important role in protecting the river from increased stormwater and sediment run-off, as well as nutrient loading from surrounding farmlands during storm events. Black Rush Lake wetland is currently used as an outdoor educational classroom by local educational institutes, including Southwest State University. Other beneficial uses of Black Rush Lake wetland include maintaining biological diversity, preserving wildlife habitat, and providing recreational opportunities. The proposed project will avoid physical alteration of the wetland areas, defined as filling, dredging, inundating, draining, or excavating. Other significant adverse impacts to wetlands, such as the discharge of elevated levels of pollutants, sediments, and nutrients, will be avoided or mitigated by the use of engineered controls, as further discussed in Items 11, 12, 13, 16, and 17. The land to the west of the Lyon County property across State Highway 23 is owned and operated by the DNR as Camden State Park. This land is used by the general public for camping, fishing, hiking, and other outdoor recreational activities. The proposed western expansion waste fill limits of the Landfill are approximately one-third of a mile away from State Highway 23 and the park boundary, and approximately a half mile from the Upper Campground. As discussed in Items 24 and 26, Lyon County will provide visual and noise screening from the park area within the property limits. No previous dust or odor problems have been reported by the park, but controls will be implemented should this become an issue. The lands adjacent to the north, south, and east of the County property are zoned agricultural. The continued use of these lands for agricultural purposes and for activities allowed by the current zoning is anticipated to continue for the foreseeable future. Attachment A provides a letter from the Lyon County Planning Department, which states that the Landfill and surrounding properties are within the Agricultural Zoning District, which limits housing density to one home per 80 acres. New commercial and residential development is not allowed within the Agricultural Zoning District. There are currently 12 residences within one mile of the Lyon County Solid Waste Management property. Potential impacts to residences are discussed further in Items 21, 24, and 26. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 15 Worksheet

17 The operation of the Landfill has been compatible with neighboring sites and nearby land uses and is not anticipated to change with the proposed development. 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 Lawn/landscaping wetlands Wooded/forest 4 6 Impervious Surfaces (2) 1 4 Brush/grassland (1) Landfill Final Cover Cropland Other: Gravel roads including shoulders and stormwater ditch, soil borrow TOTAL (1) Includes sedimentation basins for stormwater. (2) Includes lined leachate pretreatment ponds 11. 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. The main area of fish and wildlife habitats existing on the property are within the wetland areas to the south and southwest of the existing Landfill. The wetlands provide a major habitat for migratory birds and other waterfowl. Other wildlife that are likely to utilize these wetlands, either seasonally or permanently, include deer, coyote, mice, mink, muskrats, beavers, raccoons, frogs, salamanders, snakes, fish, geese, pheasants, ducks, turkey, red wing and black birds, and other non-game birds. Potential significant adverse impacts to fish and wildlife habitats within the wetlands that could result from landfill development include stormwater run-off discharges to the wetlands causing significant physical alteration and/or water quality impacts. The potential for physical alteration impacts, including water level changes, are further discussed in Item 12. Another potential impact of waste disposal near wetlands is contamination. This will be avoided through use of surface water controls and environmental monitoring. Surface water quality impacts including elevated levels of pollutants, sediments, and nutrients are discussed in Items 16 and 17. Environmental controls of the Landfill design were previously discussed in Item 6.b. Environmental monitoring is required by the MPCA to detect any sources of contamination. The environmental monitoring plan, outlined in further detail in the Permit Reissuance Update report dated July 2007 and submitted to the MPCA, is designed to identify any unexpected ground-water contamination, surface water or gas migrating from the Landfill that could impact the water quality of the wetlands. The proposed development is not expected to affect existing habitats within the 4.6-acre wetland. As previously summarized in Item 6.e., this wetland was filled in by Lyon County in 1999, in violation of Minnesota rules governing water quality and wetland nondegradation. The County subsequently undertook restoration of this wetland, which has now been completed to the satisfaction of the Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 16 Worksheet

18 MPCA. No new surface water run-off will be routed to this wetland from the proposed project, which will not take place in the immediate vicinity of the wetland, and environmental monitoring around the existing Landfill will continue to detect any unexpected future contamination. As discussed in Item 9, Lyon County has granted an easement to the USFWS for the portion of the Black Rush Lake wetland within its property limits north of County Road 59. Black Rush Lake wetland south of County Road 59 is included within the WPA designated by the USFWS. This wetland is studied and monitored by students and faculty of Southwest State University. Stormwater run-off from non-active fill areas at the Landfill is currently discharged into on-site sedimentation basins to reduce solids content prior to overland discharge to Black Rush Lake wetland. Historically, there is no evidence to suggest that fish and wildlife habitats within Black Rush Lake wetland have been impacted by Landfill operations at the site. The proposed development of Phase 9 will extend waste disposal limits to the south approximately 300 feet from the Black Rush Lake wetland easement. This is the closest that the waste limits will come to the wetland. Erosion and sedimentation at landfills are typically only a concern during construction activities. Sedimentation basins will be expanded to reduce the potential for sediment loading into the wetlands. Erosion and sedimentation control during construction and following closure are further detailed in Item 16. Currently, there is no evidence to suggest that temperature fluctuations due to run-off from the Landfill negatively impact fish and wildlife habitats of the wetlands. Minn. R , subp. 6 requires that discharges to wetlands maintain background temperatures. Because run-off temperature is usually dependant upon atmospheric conditions, there is no reason to expect post-landfill stormwater run-off temperatures to be significantly different from pre-landfill run-off temperatures. In addition to the wetland environments, there are many wildlife habitats within Camden State Park and fish habitats within the Redwood River located to the west of the County property. The nearest lake, Brauner Lake, is located approximately one mile southwest of the Landfill. The proposed project is not expected to affect these environments. Control and mitigation of surface-water impacts to the Black Rush Lake wetland will, in turn, limit similar impacts to the downstream surface waters. Following final closure of the entire Landfill, the site will be converted to open space. 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 DNR Natural Heritage and Nongame Research program has been contacted give the correspondence reference number: ERDB Describe measures to minimize or avoid adverse impacts. The DNR identified three known occurrences of rare or native plant communities near the existing and proposed Landfill sites. However, given that the project will not impact the Redwood River, DNR staff does not believe the project will affect any known occurrences of rare features. See Attachment B. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 17 Worksheet

19 There are no endangered or threatened species identified within Lyon County on the USFWS Web site. 12. Physical Impacts on Water Resources. Will 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. As previously described in Item 6.b., portions of Phases 9, 10, and 11 expansions will be constructed below the water table. Dewatering around new fill areas will be necessary during construction of the liner, and initial waste placement, to reduce the upward buoyant force of the ground water until enough waste has been placed to counteract this force. Ground water produced from these activities will be discharged either to a perimeter stormwater drainage ditch or directly to the closest sedimentation basin. Although not expected, if contamination were detected within the removed ground water, it would be treated as leachate. The potential effect of dewatering activities on the water level within the wetlands areas was evaluated in a hydrogeologic study completed for the site, included as Attachment C. No significant potential water level impact from dewatering activities was identified. Based on the described controls and modeling results, there is no reason to suspect that the project dewatering activities will result in either drainage or permanent inundation of the wetlands. New perimeter drainage ditches will be constructed around the proposed Landfill expansion phases to collect and transfer stormwater run-off to sedimentation basins. The perimeter drainage ditches have been designed for the expected run-off that would result from a 24-hour, 25-year storm event based on drainage area. As previously presented in Item 6.b., run-off will be routed to sedimentation basins designed to reduce solids content prior to discharge to the Black Rush Lake wetland. There is no indication that stormwater run-off from the Landfill currently causes negative impacts to the wetland, such as excessive sedimentation. Sedimentation controls are described in further detail in Item Water Use. Will 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. Because the proposed expansion will extend below the ground-water table, dewatering may be necessary during liner construction and initial MSW filling operations, depending upon infiltration rates. Dewatering will cease when enough MSW has been disposed of to counteract the upward buoyant pressure from ground water on the barrier layer of the liner. A DNR Water Appropriation Permit is required for removal of more than 10,000 gallons per day or 1 million gallons per year. A permit should not be required for this project as the maximum amount of water estimated to be removed during dewatering each year is approximately 262,800 gallons (0.5 gallons per minute x 60 minutes/hour x 24 hours/day x 365 days/year = 262,800 gallons). However, the quantity of water pumped will be monitored regularly and a permit obtained in the future, if needed. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 18 Worksheet

20 Existing ground-water monitoring wells located within the footprint of the proposed expansion will be abandoned and properly sealed in accordance with state and local requirements prior to construction of the expansion phases. New ground-water monitoring wells will be installed as part of the modified groundwater monitoring program to monitor ground-water quality and elevations around the perimeter of the Landfill, as outlined in the Environmental Monitoring Plan provided in the permit application. The environmental monitoring system for the proposed expansion is shown in Figure 10. No water supply wells will be installed or affected as part of the expansion. Existing public and private water supply wells within one mile of the project site are presented in Figure 3. It is anticipated that all ground water collected by the IGS will be discharged to the closest sedimentation basin. Given that dewatering will occur in different phases of the development at different times, the predicted volume of ground water being directed to any basin is considered temporary and able to be absorbed by the overall capacity of each basin. This was verified by comparing the percentage of dewatering volume to the designed capacity of the smallest basin (677,000 cubic feet). Given that 262,800 gallons of ground water to be removed per year equates to 96 cubic feet per day, and 96 cubic feet per day is the equivalent of 0.01 percent of the capacity of the smallest basin (677,000 cubic feet), the effects of the dewatering on the basins, even during rain events, should be minimal. 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. 15. Water Surface Use. Will 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: 40.3 acres; 985,000 cubic yards. Describe any steep slopes or highly erodible soils and identify them on the site map. Describe any erosion and sedimentation control measures to be used during and after project construction. Acreage identified only includes newly developed areas. A majority of the existing slopes of the facility are approximately 25 percent. Maximum final cover slopes of the proposed expansion zones will be designed at 33 percent, as shown in Figures 6 and 7. Final cover slopes exceeding 20 percent will be designed with permanent terraces and other controls to minimize erosion and provide stability, in accordance with MPCA guidance. The terraces will be designed so that drainage lengths on steep slopes do not exceed 40 vertical feet. The stormwater management system is discussed in greater detail in Item 17.a. The area to be developed is not thought to contain peat or highly erodible soils. The surface water management plan for the Landfill will minimize erosion and sedimentation impacts. Conditions conducive to significant soil erosion and sedimentation typically exist during the construction and active operation of waste cells. Removal of natural ground cover creates potential erosion conditions from the movement of water and wind. During the construction phases of the project, erosion will be minimized by the following techniques: Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 19 Worksheet

21 Water Erosion. Areas required for facility construction will be cleared and grubbed. Top soil will be stripped and stockpiled for future restoration activities. Run-off that does occur will be directed to open ditches, which will then direct water to the existing Landfill sedimentation and infiltration areas. To reduce the erosion impact from run-off prior to establishing vegetative growth, silt fences, hay bales, netting, and mulch will be used in areas susceptible to erosion. During project operation, ditches and berms will control run-off resulting from at least the 24-hour, 25-year storm in a manner to reduce erosion. Potential run-on resulting from the 24-hour, 25-year storm will be diverted to sedimentation basins around the Landfill site to prevent flow onto the active portion of the Landfill. Erosion of the drainage layers placed above the Landfill liner will be reduced by immediate placement of waste following liner construction. Straw or hay will be used for temporary erosion control if waste filling is not anticipated to begin immediately. This measure will also provide freeze protection and protection from wind erosion. Any straw or hay placed on the liner will be removed prior to waste placement to avoid potential biofouling of the drainage layer. All culverts and open channels will be constructed in a manner that will minimize erosion both during and after construction. Ditches generally will be grass lined. Where high run-off velocities are expected, ditches will be rock lined to provide further erosion protection. Standard erosion control measures will be used to protect temporary stockpiles of soil as well. Other possible temporary and/or permanent erosion control measures include the use of riprap, straw bales, silt fences, swales and berms, surface roughening, seeding, and matting and mulching. Final restoration of disturbed areas is intended to enhance the appearance of the site and make it compatible with the surrounding region. The land disturbed temporarily by construction activities will be graded and seeded. The reseeding method used at the site will be in accordance with those identified in the permit documents approved by the MPCA. Wind Erosion. The site is surrounded by low vegetative cover, along with mature trees, which provide a wind break. During construction, dust control measures will continue to involve spraying of traffic areas with water, as necessary. Permanent wind erosion control will be accomplished by planting hardy perennial grasses, legumes, or other ground covers selected for their ability to establish themselves quickly and promote soil stabilization. 17. Water Quality Surface-water Run-off. a. Compare the quantity and quality of site run-off before and after the project. Describe permanent controls to manage or treat run-off. Describe any storm-water pollution prevention plans. The current stormwater management system at the Landfill includes a perimeter collection ditch on the east boundary of the Landfill, and sedimentation basins located on the north, south, and southwest. Run-off from the northwest portion of the Landfill is directed to the north sedimentation basin, while the remainder of the run-off drains to the southern basins. Stormwater run-off from the active fill areas is either collected in the active cell and treated as leachate, or routed away from the waste to be collected in the perimeter ditches and routed to the sedimentation basins. Without the proposed development, stormwater would run off from approximately 40.6 acres of landfill final cover including Phase 7. Existing stormwater controls and basins are presented in Figure 2. During the filling of each proposed expansion cell, benches will be constructed within the Landfill cover to prevent uninterrupted flow distances from exceeding 200 feet. The existing southwest sedimentation basins will be relocated, the south-central basin will be expanded, and a new Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 20 Worksheet

22 northwest basin will be constructed. The existing north and southeast sedimentation basins will remain in use. All sedimentation basins will be designed to temporarily store stormwater resulting from a 24-hour, 25-year precipitation, which for the Lyon County area is approximately 4.0 inches. Figure 5 presents the new sedimentation basin locations. Stormwater from the vegetated final cover of the proposed expansion areas will be collected by stormwater channels constructed on the terraces, located on the 3:1 sideslopes, and connected to the existing or proposed perimeter drainage system or directly to the sedimentation basins. Stormwater drainage from developed areas will be directed to sedimentation basins through the existing stormwater collection system. Excluding existing Landfill area, a total of approximately 40.3 acres of final cover run-off will be generated upon completion of the proposed expansion. A majority of this area currently drains to Black Rush Lake wetland. Since run-off directed towards sedimentation basins never contacts the waste material within the Landfill, elevated levels of pollution are not expected. Run-off from vegetated final cover areas may collect a minor amount of sediment. Sedimentation basins at the Landfill have been designed to achieve 80 percent sediment removal efficiency, in accordance with MPCA General Stormwater Permit requirements. Soils to be used for the drainage layer above final cover will not contain high levels of nutrients for the purpose of minimizing possible nutrient loading within run-off. b. Identify routes and receiving water bodies for run-off from the site; include major downstream water bodies as well as the immediate receiving waters. Estimate impact run-off on the quality of receiving waters. As the Landfill expansion is developed in phases, run-off from areas that reach permitted elevations will generally be directed to the west. A combination of terraces, channels, and downdrains will direct flows to new and existing sedimentation basins that will be utilized for stormwater management purposes. Figures 8, 9, and 10 show stormwater drainage features of the proposed expansion. The Landfill is situated on the boundary of the Redwood River and Cottonwood River watersheds. Run-off from portions of the Landfill within the Redwood River watershed will drain to the south-central and southeast sedimentation basins prior to discharge to a culvert that diverts flow overland to the south into Black Rush Lake wetland. Water from the wetland flows south and west and eventually enters the Redwood River. Run-off from portions of the Landfill within the Cottonwood River watershed that drain to the northwest and southwest sedimentation basins will be allowed to flow overland to the west and southwest onto the adjacent agricultural fields. Run-off from the north side of the Landfill is diverted to north and northwest sedimentation basins. Water that does not infiltrate into the agricultural fields would run off into a manmade drainage channel northwest of the Landfill, which eventually drains to the Cottonwood River. As previously discussed, stormwater run-off from non-active fill areas will not be exposed to waste materials that could negatively affect water quality. Run-off from developed areas will not be routed toward impervious pavement that may accumulate other sources of pollutants, such as oils and chemicals from vehicle storage. Minn. R , subp. 6 requires that discharge to wetlands maintain background levels of dissolved oxygen, ph, and temperature in order to avoid significant adverse impacts. Sediment in the wetland discharge will be controlled to prevent any decrease in dissolved oxygen from occurring, or Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 21 Worksheet

23 sediment buildup causing damage to wetland fish and wildlife habitats. Controls to prevent increased sediment loading impact from discharged run-off include the growth of dense vegetation on the final cover, as well as construction of additional sedimentation pond capacity. Downstream portions of the Redwood River, the receiving waters for any overland run-off from the Black Rush Lake wetland, have been identified as having impairments such as elevated turbidity, fecal coliform, fish index of biotic integrity, mercury, and ammonia. Because of the measures that will be taken to protect the wetland from impacts, as well as the benefit of the wetland itself as a natural pollutant and sediment filtering agent, it is not expected that the water quality of the Redwood River will be further impaired by the proposed project. The Landfill development was designed to attempt to keep stormwater run-off from the final cover and non-fill areas within each of the respective watersheds. Upon final cover construction of the proposed expansion, approximately five acres of Landfill area that is currently located in the Cottonwood River watershed will drain to Black Rush Lake wetland within the Redwood River watershed. The additional water will partially compensate for approximately 12 acres of Landfill area within the Redwood River watershed that currently drain to the north sedimentation basin located within the Cottonwood River watershed, and will return stormwater run-off areas more closely to historic conditions. The Redwood River watershed covers approximately 450,000 acres, while the Cottonwood River watershed covers approximately 822,000 acres. The Landfill expansion is not expected to have a significant impact to the overall quality of water within either watershed. 18. Water Quality Wastewater. a. Describe sources, composition and quantities of all sanitary, municipal and industrial wastewater produced or treated at the site. The Landfill generates MSW leachate. Leachate is generated in MSW landfills as a result of the small amount of liquid found in household waste, precipitation falling onto the waste during filling activities, and minimal percolation through the final cover system. Leachate has a variable composition that depends upon waste characteristics, rate of moisture infiltration, and landfill age. Generally, for a given layer of waste, the strength of the leachate will be related to the biological degradation of the waste. Typically, the leachate will increase in strength over the first few years, and then gradually decrease in strength. An estimate of the amount of leachate that will be generated by the Landfill was calculated for both the active and closed phases. During the active phase of operation, approximately 150,000 to 160,000 gallons per acre per year of leachate will be generated, while approximately less than 100 gallons per acre per year will be generated after closure and installation of the final cover of the Landfill. The design of the leachate collection, storage, and treatment/disposal system is based on these leachate generation rates. Currently, leachate is being recirculated into Phase 7 as part of a pilot study. Upon completion of the pilot study, results and recommendations will be submitted to the MPCA for review. If approved by the MPCA, the proposed expansion will utilize full-scale leachate recirculation. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 22 Worksheet

24 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. Not applicable. c. If wastes will 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. 19. Geologic hazards and soil conditions. a. Approximate depth (in feet) to Ground water: 3.5 minimum; 7.5 average. Bedrock: 300 minimum; 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. There are no geological hazards on the site. b. Describe the soils on the site, giving Natural Resources Conservation Service classifications, if known. Discuss soil granularity and potential for ground-water contamination from wastes or chemicals spread or spilled onto the soils. Discuss any mitigation measures to prevent such contamination. The Landfill lies on the southwestern slope of a northwest to southeast trending moraine deposit. The soils underlying the Landfill are primarily glacial tills containing lenses of sand, silty sand, and silt. The sands and silts are not extensive, but are more numerous toward the center of the moraine deposit. The tills consist of sandy lean clay with occasional layers of fat clay. The near-surface clay sediments are mottled brown and gray, becoming grayer at depth. Some of the sediments in the mottled zone are fractured vertically. Along the southern boundary of the eastern half of the site, the near-surface sediments consist of marl and organic silts and clays underlain by clay till. The uppermost bedrock unit (estimated to be approximately 300 to 400 feet below ground surface) consists of 200 to 300 feet of Cretaceous sand and shale overlying Precambrian crystalline basement rock. Waste acceptance controls, as outlined in Item 6, will prohibit disposal of hazardous materials at the Landfill. Leachate from the Landfill can contain parameters such as volatile organics and metals. Current methods that will continue to be employed to prevent ground-water contamination include: Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 23 Worksheet

25 a composite landfill liner system; a composite leachate pretreatment pond liner system; a leachate collection system to remove leachate from the Landfill and help protect the integrity of the liner; double-contained leachate transmission piping; environmental monitoring; and leak detection systems. Ground-water flow direction is generally southward in the water table aquifer and northwestward in the lower, semi-confined, sand and gravel aquifer. Historical ground-water monitoring at the Landfill has shown that ground water within the lower, sand and gravel aquifer has natural concentrations of inorganics such as arsenic, boron, manganese, and nitrate in exceedance of MPCA Intervention Limits. It has been determined that these exceedances are not caused by the Landfill because sampling results show that the concentrations are higher in the lower, semi-confined aquifer than the upper, unconfined aquifer. Furthermore, similar concentrations have been detected upgradient and downgradient of the Landfill. These results are provided to the MPCA in Annual Reports. Elevated arsenic concentrations in ground water are common in western Minnesota. Concentrations of volatile organic compounds have been detected occasionally, but have never exceeded corresponding Intervention Limits. 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 will be modified for recycling. If hazardous waste is generated, indicate if there is a hazardous waste minimization plan and routine hazardous waste reduction assessments. Sludge is expected to be generated in the leachate pretreatment ponds. The sludge material will be analyzed and screened for hazardous concentrations of various constituents. Although it is not expected, if the sludge is found to be hazardous, it will be disposed of accordingly. If concentrations of the constituents do not exceed hazardous waste criteria, the sludge will be dewatered and disposed of at the Landfill. 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 ground water. If the use of toxic or hazardous materials will 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. The following aboveground storage tanks (ASTs) are present at the Landfill: Two 1,000-gallon diesel fuel ASTs One 500-gallon gasoline AST One 460-gallon used oil AST Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 24 Worksheet

26 The following underground storage tank (UST) is present at the Landfill: One 15,000-gallon leachate UST The locations of these tanks are presented in Figure 2. Each of the ASTs is double-walled, providing secondary containment and interstitial space monitoring should a release occur. The underground leachate tank is also double-walled and interstitial monitoring is conducted to detect leaks. A leak from any of the inner tank shells would be detected and contained prior to release from the outer tank shells. If a leak were to occur from the inner tank shell, the liquid would be immediately pumped from the tank for disposal and the damaged tank would be removed and/or repaired, in accordance with applicable regulations. The leachate storage tank will continue service for existing portions of the Landfill, as well as Phase 8. Leachate from Phases 9 to 11 expansion areas will be routed to newly constructed leachate treatment ponds for temporary storage. 21. Traffic. Parking spaces added: 0 Existing spaces (if project involves expansion): Estimated total average daily traffic generated: vehicles Estimated maximum peak hour traffic generated (if known) and its timing: Not known Provide an estimate of the impact on traffic congestion on 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. Traffic for the Landfill typically comes from State Highway 23, exiting and heading east on County Road 59 for approximately one mile, then turning north for approximately one-quarter-mile on 200 th Avenue. Based on information provided by the County Landfill operations staff, Landfill traffic is relatively steady throughout the day. The recent daily maximum number of vehicles into the Landfill was 106. Recent traffic counts have been completed by County operations personnel for County Road 59, which yielded 100 vehicles per day in 2005, and State Highway 23, which yielded 258 total vehicles per day in May Approximately 202 vehicles were found to be trucks, while the remaining 56 were cars. To date, no traffic congestion issues have been identified on roads in the nearby area. Because this property has been used for waste disposal since 1971, no impacts to traffic congestion are expected as a result of an increase in the Landfill s permitted capacity. A significant increase in the current disposal rate and/or traffic is not expected. An estimated additional vehicles per day are expected during construction activities associated with construction of the Landfill expansion. This will not have a significant impact on existing traffic conditions as deliveries will be coordinated during off-peak hours. 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. Vehicle-related exhaust emissions during expansion construction phases will be temporarily greater due to an increase in trucks and heavy equipment operations. However, these activities will not be sustained. Normal operations during the active phase of the project are expected to be unchanged. Therefore, overall vehicle-related air emissions are not expected to change due to the proposed expansion. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 25 Worksheet

27 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. LFG, which primarily consists of carbon dioxide and methane, is generated as a result of the biological decomposition of waste material within the landfill. Methane may pose a safety problem if it is mixed with air at concentrations of greater than 5 percent and less than 15 percent. The proposed Landfill expansion includes the gas control and monitoring system previously described in Item 6.b.III. Carbon dioxide and methane are also two of the primary greenhouse gases, atmospheric gases that trap heat near the earth s surface, causing the earth s climate to warm. The main sources of worldwide greenhouse gas emissions are the combustion of fossil fuels to run vehicles, heat buildings, and produce electricity. While landfills are a source of greenhouse gases, they do not represent a significant percentage of greenhouse gas emissions. In Minnesota, landfills contribute approximately one to four percent towards total inventoried Minnesota greenhouse gas emission sources. Of the greenhouse gases emitted by all 21 MSW landfills in Minnesota, the Lyon County Landfill contributes approximately four percent. Leachate recirculation does typically result in greater emissions of LFGs, and continuation of the leachate recirculation system at the Lyon County Landfill will likely result in an increase in emissions over that which would occur without the leachate recirculation system. However, the benefits associated with leachate recirculation (as outlined in Item 6.b.III) are significant. Finally, as discussed in Item 6.b.III, a LFG collection system will be installed at the Landfill when required by federal standards, and this will result in a significant reduction of greenhouse gas emissions. It should also be noted that under Minn. Stat. 216H.02, the state of Minnesota is engaged in a process to determine how greenhouse gas emissions will be reduced in the state to meet statutory goals. When future regulations related to climate change or other air pollution issues are established, this proposed project, as well as other entities, will likely be required to meet those regulations. This may result in earlier operation of the active gas recovery system than required by federal law, or implementation of other measures that reduce emissions of greenhouse gases. 24. Odors, noise and dust. Will 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.) The proposed expansion is a continuation of current landfilling activities. Therefore, existing odor, noise, and dust conditions at the site are not expected to change significantly after completion of the expansion. Existing controls to minimize and monitor the quantities and intensity of odors, noise, and dust will be continued throughout the extended service life of the Landfill. Land adjacent to the Landfill is used for agricultural purposes, primarily corn and soybean production. The closest residence to the existing Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 26 Worksheet

28 Landfill is located approximately 500 feet northeast of the site. Recreational activities at Camden State Park will be located approximately one-half-mile from the proposed Landfill expansion. No formal complaints regarding odors, noise or dust have been made by nearby residents or recreational users. Odors. The use of daily and intermediate cover soils facilitates odor control of the recently disposed waste material. The County has increasingly monitored Landfill odors since the implementation of the pilot leachate recirculation study. Results, as reported to the MPCA in the annual summary report, have indicated no increase in odor levels except during short periods of time when construction in the recirculation cell has exposed the waste. These instances are rare and of a temporary nature. As previously discussed, LFGs will eventually be collected by utilizing an active system. The proposed active venting system will transfer the gas to either a flare or LFG-to-energy system for odor reduction. Also, the proposed leachate holding ponds will be aerated to prevent them from becoming a source of odor, which could occur if they were allowed to become stagnant. Noise. Construction of the proposed expansion phases will likely result in short-term increases in the noise generated at the site, during the actual construction activities. Construction activities will be temporary in duration and contractors will comply with local noise ordinances. Construction will take place during daylight hours. During regular Landfill operation, noise is generated by equipment used for hauling, compacting, and covering refuse. With the proposed western expansion, these activities will move closer to Camden State Park. Lyon County will be constructing noise berms with planted dense vegetation to the west of the expansion areas. Figure 11 shows the screening berm plan. Also, no heavy equipment is operated outside of the Landfill hours of 6:00 a.m. to 4:30 p.m., Monday through Friday, and 6:00 a.m. to 12:00 noon on Saturdays. Dust. Fugitive dust emissions at the Landfill are caused by refuse trucks and earth-moving equipment during operation and cell construction. Fugitive dust emissions are controlled by the following practices: Proper maintenance and repair of facility gravel access roads Application of water to areas that produce dust, when necessary Cover and revegetation of inactive areas 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. a. Archaeological, historical, or architectural resources. The Minnesota State Historic Preservation Office provided correspondence (Attachment D) indicating that there are three archaeological properties in the area. The general locations of the sites are outside the proposed Landfill limits, as presented in Figure 3. However, two of the sites, identified as Dwire Farm and Brush Lake Hill, overlap and are located within the existing Landfill limits in the vicinity of Phase 7. In 2003, the Minnesota Office of the State Archaeologist (OSA) performed a field investigation of these sites and determined that due to significant historic disturbance, there are no further archaeological constraints to proceeding with plans for further landfill development. The OSA correspondence is included as Attachment E. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 27 Worksheet

29 b. Designated parks, recreation areas, or trails. As previously described in Item 9, the land to the west of the Lyon County property is owned and operated by the DNR as Camden State Park. This land is used by the general public for camping, fishing, hiking and other outdoor recreational activities. The proposed western expansion waste fill limits of the Landfill are approximately one-third of a mile away from State Highway 23 and the park boundary and approximately one-half mile from the Upper Campground of the park. As discussed in Items 24 and 26, Lyon County will provide visual and noise screening from the park area within the County s property limits. No previous dust or odor problems have been reported by the park, although controls will be implemented should this become an issue. c. Other unique resources. As previously described in Items 9 and 11, the County has granted to the USFWS an approximate 37-acre easement of the 333-acre Black Rush Lake wetland as part of a larger WPA. This easement is located on the southern portion of the County property, with the remainder of the wetland extending further south. The WPA consists of approximately 973 acres of restored wetland and upland habitats. The easement portion of Black Rush Lake wetland within County property boundaries located north of County Road 59 is not part of the WPA. Eventually discharging to the Redwood River, the Black Rush Lake wetland plays an important role in protecting the river from increased stormwater run-off and sediment loading, as well as nutrient loading from surrounding farmland during storm events. Other beneficial uses of Black Rush Lake wetland including maintaining biological diversity, preserving wildlife habitat, and providing recreational and educational opportunities. 26. Visual impacts. Will 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. The proposed expansion is a continuation of current landfilling activities. The proposed vertical and horizontal landfill development calls for an increase in elevation of the Landfill. The County will construct an earthen berm and plant dense vegetation along the western portion of the property to visually screen the Landfill from users of Camden State Park and traffic along State Highway 23 (see Figure 11). Trees have already been planted along the southern portion of the existing Landfill to screen operations from Black Rush Lake wetland, and a site berm with trees is established on the eastern property boundary. 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 will be resolved. If no, explain. The Lyon County Board of Commissioners approved a Conditional Land Use Permit for this Landfill in The operation of the Landfill is a conditionally approved use in this zoning district. The Lyon County Comprehensive Solid Waste Management Plan Update (the Plan) was prepared in October 2003 and was approved by the MPCA. The Plan addresses solid waste planning for Lyon County and incorporates solid waste disposal needs for the additional six counties that the Landfill serves. Chapter III of the Plan presented a review of alternatives. The Southwest Regional Solid Waste Commission completed a Regional Review of Alternatives that was updated in 2002 and incorporated into the Plan. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 28 Worksheet

30 The document concluded that continued landfilling is the most prudent and feasible solid waste disposal alternative, due to lack of processing facilities, and the inability to direct waste to preferred facilities through ordinance. The Lyon County Board of Commissioners also approved the decision for the western expansion of the Landfill, as stated in correspondence provided as Attachment A. 28. Impact on infrastructure and public services. Will 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 lands adjacent to the north, south, and east of the County property are within the Agricultural Zoning District. The use of these lands for agricultural purposes and for activities allowed by the current zoning is anticipated to continue for the foreseeable future. Attachment A provides a letter from Lyon County Planning Department, which states that properties within the Agricultural Zoning District are limited to a housing density of one home per 80 acres. New commercial and residential development is not allowed within the Agricultural Zoning District. To the west of the County property is Camden State Park, as previously described in Items 9 and 25, which will continue to be used as state park land in the foreseeable future. No environmental impacts to the air or surface or ground water have been identified from any projects in the vicinity of the Landfill. Because of the agricultural nature of the surrounding lands, crop farming and feedlot operations are the only activities identified as having potential environmental impacts that could interact with the proposed project to create significant cumulative impacts. However, no significant problems are known to exist with any specific operations of this type. Environmental impacts known to exist from past or present Landfill activities and the mitigative measures employed or proposed to prevent or minimize these impacts have been identified in this EAW. It is not expected that the proposed project will interact with any existing or future projects near the Landfill to cause cumulative impacts. 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. No additional adverse environmental impacts have been identified that are not addressed in this EAW. Lyon County Sanitary Landfill Expansion Environmental Assessment Lyons Township, Minnesota 29 Worksheet

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43 ATTACHMENT A May 10, 2007 To Whom It May Concern: Subject: Land use The Lyon County Regional Landfill is located in Section 9 of Lyons Township, Lyon County Minnesota. The Landfill along with the surrounding properties is located in the Agricultural Zoning District. Regulations within the Agricultural Zoning District can be found in the Lyon County Zoning Ordinance. For convenience the Lyon County Zoning Ordinance can be found at Permitted land uses in the Agricultural District are generally associated with the growing, production and/or harvesting of crops, livestock, livestock products, limited agriculture, land in government conservation programs and incidental and accessory activities and uses. Past actions by the Lyon County Planning Commission and the Lyon County Board of Commissioners support compatible agricultural uses within the vicinity of the Lyon County Regional Landfill. The Lyon County Zoning Ordinance does not allow development, or low density housing within the Agricultural District. The density for a dwelling is one home per 80 acres. As much of the neighboring parcels surrounding the landfill are owned by the public or are in parcels less than 80 acres. In conclusion, the Lyon County Zoning Ordinance supports the Lyon County Regional Landfill. In addition the uses supported within the Agricultural District are seen as compatible with a neighboring landfill. Sincerely, John Biren Lyon County Planning and Zoning Administrator

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48 ATTACHMENT C IntegralConsultingInc AirportWay Suite370 Broomfield,CO80021 telephone: facsimile: MEMORANDUM To: From: Date: Subject: ProjectNo.: RandallJ.Sippel,PG,R.W.Beck DavidMixon,IntegralConsultingInc. ChristineHawley,IntegralConsultingInc. July 10 th,2007 LyonCountyLandfillDewateringSupport C366 ThismemorandumpresentsIntegral sevaluationofthepotentialimpactsoftheproposed LyonCountyLandfillexpansionprojectonthewaterbalanceoftheBlackRushLakeWetland ProtectionArea. INTRODUCTION Project Setting TheLyonCountySanitaryLandfill(SW23),ownedandoperatedbyLyonCounty,islocated insouthwestminnesotanearthecityofmarshall.topographyinthevicinityofthelandfillis relativelysubtle,withelevationsrangingfrom1460to1530feetabovemeansealevel(amsl). Thelandfillliesonglacialandpostglacialdepositsofvariablethicknessandtexture.Two aquifershavebeenidentifiedintheglacialdeposits:(1)anunconfinedwatertableaquifer presentinnearsurfacetilldeposits,and(2)adeeper,semiconfinedaquiferlocatedinsandy depositsbeneaththetilllayer.shallowgroundwaterbeneaththesiteisgenerallywithin5to 10feetofthegroundsurface(1450to1510ftamsl). Problem Statement LyonCountyhasproposedalandfillexpansioninthesouthernportionofthelandfill property.theexpansionwillinvolveexcavationofa1012acrewastecelltoanapproximate elevationof1460ft,whichrequiresdiggingbelowtheshallowgroundwatertableinthearea. Thewastecellwillbedewateredduringexcavation,construction,andduringtheinitialphase

49 LyonCountyLandfillDewateringSupport July3 rd,2007 Page2of7 offilling.lyoncountywouldliketoknowifdewateringfortheproposedexpansionwill haveanimpactontheblackrushlakewetlandprotectionarea. Toanswerthisquestion,Integralevaluatedwhetherinflowofgroundwatertotheproposed landfillexpansionareawouldbesignificantrelativetotheoverallwaterbalanceoftheblack RushLakeWetland.Applyingthisapproach,ifestimatedgroundwaterinflowtothe proposedexcavationisfoundtobesignificantrelativetothemagnitudeofcomponentsofthe wetlandwaterbalance,thenadditional,moredetailedinvestigation/analysis,possibly includingacompletehydrologicmodelofthearea,wouldberecommended.ifestimated groundwaterinflowtotheproposedexcavationisfoundtobeinsignificantrelativetothe magnitudeofthecomponentsofthewetlandwaterbalance,thenitcanbeconcludedthatany hydrologicimpacttothewetlandwouldalsobeinsignificant.theinflowofgroundwaterto theproposedlandfillexpansionareawasconservatively(high)estimatedusingthe groundwatermodelingsoftware,modflow(harbaughandmcdonald1996).itshouldbe notedthatthemodflowcodewasusedexclusivelytoestimateinflowtothewastecell,and acalibratedsitegroundwatermodelwasnotgenerated. ANALYSIS Task 1 Preliminary Water Balance for the Black Rush Lake Wetland Protection Area TohelpassesswhethertheproposedlandfillexpansioncouldhaveanimpactontheBlack RushLakeWetlandProtectionArea,apreliminaryassessmentofthewaterbalanceforthe wetlandareawasdeveloped.thisbriefevaluationidentifiedthemajorelementsofthewater balanceandfocusedonsemiquantitativeassessmentoftheprimarylossterm, evapotranspiration(et).becausethedewateringactivitiesfortheproposedlandfillexpansion mayconstituteanadditionalwaterbalancelossterm(i.e.,reducedgroundwaterinflowtothe wetland),thisassessmentisintendedtoprovideperspectiveonthemagnitudeofany reductionsingroundwaterinflowresultingfromdewateringoperations(task2)relativetothe overallwetlandwaterbalance. Integralreviewedrelevantinformationregardingthesite,localhydrologyandhydrogeology, andpubliclyavailableinformationdescribingregionalevaporationandtranspirationrates. IntegralalsocontactedtheU.S.Fish&Wildlife(USFW)Servicetoestablishthenatureof wetlandmanagementpractices. AccordingtoUSFWpersonnel,theBlackRushLakeWetlandwasrestoredin1998afteryears ofagriculturalusage.therestorationwasaccomplishedbytheconstructionofseveralberms andtheblockageofaditchthatpassesthroughthewetland.waterlevelsinthewetlandare maintainedthroughouttheyearbyadjustmentofcontrolstructuresatinflowandoutflow locations.thewetlandisoccasionallydrainedformaintenance.whilethewetlandis IntegralConsultingInc.

50 LyonCountyLandfillDewateringSupport July3 rd,2007 Page3of7 assumedtobeincommunicationwiththeshallowgroundwaterintheregion,usfw personnelindicatedasignificantcontributiontothewetlandwaterbalancecomesfromsurface water,includingwaterdivertedtothewetlandviatheditchmentionedabove.specificdata onmaintenancepractices,inflowrecords,andoutflowrecordsfromthewetlandwerenot available. Inflowtermsforthewetlandwaterbalanceare: Channelizedsurfacewaterinflow Surfacewaterrunofffromthesurroundingcatchment Groundwaterinflow Directprecipitation Outflowtermsforthewetlandwaterbalanceare: ET(openwaterevaporationplusplanttranspiration) Dischargetogroundwater Channelizedsurfacewateroutflow Evapotranspiration(ET)islikelytobetheprimarylosstermforthewetlandwaterbalance. Surfacewateroutflowmayalsobeverysignificant;however,norecordswereavailableto allowestimationofthishumanmanagedterm.usinglakeevaporationratespublishedbythe U.S.NationalWeatherService(BedientandHuber1992),theaverageevaporationfromthe openwatersurfaceofthewetlandisestimatedtoberoughly580gallonsperminute(gpm)(3.0 x10 8 gallonsperyear).vegetationcoveredwetlandstypicallyhavegreateretratesthanthose measuredforopenwater,thoughthemagnitudeofthatincreasevariessignificantlyby vegetationtype,foliardensity,andclimaticconditions.becausetheblackrushlakeismostly coveredbyhydrophyticvegetation,theaverageetrateisexpectedtobeasmuchas50%to 150%greaterthantheopenwaterevaporationratealone(SanchezCarrilloetal.2001). Task 2 - Landfill Expansion Dewatering Calculations Toprovideanestimateofthedewateringratefortheproposedlandfillexpansionarea,the U.S.GeologicalSurvey smodflownumericalgroundwaterflowcode(harbaughand McDonald1996)wasusedasacalculationtooltoestimategroundwaterinflowtothe proposedlandfillexpansionunderdrainsystem. IntegralreviewedrelevantdataprovidedbyR.W.Beckonlandfilldesignandthelocal groundwatersystem,includingthehorizontalandverticalextentoftheexistinglandfilland proposedexpansion,generaldesignoftheunderdrainsystem,sitegroundwaterwell construction,aquiferparameters,andgroundwaterelevations. IntegralConsultingInc.

51 LyonCountyLandfillDewateringSupport July3 rd,2007 Page4of7 Basedonthisdatareview,Integraldevelopedasimplerepresentationofthelocalgroundwater flowsystemutilizingthemodflowcodewiththegroundwatervistasv.4interface (RumbaughandRumbaugh2002).Forthisrepresentation: Asimplifiedhydraulicgradientwasgeneratedbasedonavailabledata.Toproducea conservativelyhighestimateofthedewateringrate,aspringdatasetforgroundwater levels(march23,2006)wasused.fromthesedata 1,asimplifiedgroundwatersurface wasgeneratedtomimictheobservedgradientof0.021ft/ftneartheproposed expansionarea. Uniformaveragehorizontalandverticalhydraulicconductivityvalues(Kx,Ky,andKz)were assignedtothearea(i.e.,therewasnosimulationofheterogeneitysuchassandlenses). Previoushydrogeologicinvestigationsprovidedhydraulicconductivity(K)estimates basedonslugtestresults.kvaluesforwellsandboringsscreenedintheshallow watertableaquiferwerecomparedtothesedimenttextureindicatedforthematerial acrossthescreenedinterval.thesevaluesincludedwellsscreenedacrosssandlenses, clay,andsilt. 2 TheKvaluesforthe10wellsandboringsconsideredrangefrom to0.519ft/day.thegeometricmeanofthisgroupofkvalues(0.0108ft/day)wasthe valueusedforthehorizontalkinthemodel.astandardvalueof1/10 th thehorizontal K( ft/day)wasusedfortheverticalK. TheBlackRushLakeWetlandProtectionAreawasnotspecificallysimulatedaspartofthe model.thesouthernmodelboundarywassetatthenorthernendofthewetland,and designatedasaconstantheadboundary.thisassumptionisconservativeinthe estimationofinflowtotheproposedlandfillexpansionareainthatitcouldleadtoa slightoverestimationoftheinflowbypreventingsimulationofdrawdownbeyondthe edgeofthewetland.thestudyresultssupportthisassumption;theinflowratewas foundtobedeminimusrelativetothemagnitudeofthewetlandwaterbalance, indicatingthattheinflowisnotlikelytohaveanyeffectonthewetlandhead.the northernmodelboundarywasalsosetasaconstantheadboundarybasedonan analysisofthelocalgroundwatergradient.becausethelocalgradienttrends predominantlynorthsouth,theeasternandwesternboundariesweresetasnoflow boundaries. Rechargewasnotspecificallysimulatedaspartofthismodel,butwasgenerallyaccounted forbyuseofconstantheadboundariesandanimposedgradient. 1 Thewellsusedtogeneratetheinitialgroundwatersurface:MW4,MW6,MW8,MW9,MW12,MW14, MW15,MW19,MW15. 2 SlugtestpredictedKvaluesfromtenwellswereconsideredreasonablyrepresentativeofthematerials oftheshallowaquiferintheareaoftheproposedlandfillexpansion:p2,p3,p4,p5,p11,p13,p22a, P23A,P24A,P24B IntegralConsultingInc.

52 LyonCountyLandfillDewateringSupport July3 rd,2007 Page5of7 TheMODFLOWdrainpackagewasusedtosimulatetheproposedunderdrains.Basedon preliminaryengineeringinformationprovidedbyr.w.beck,thedrainsweresettoan elevationof1460ftamsltorepresentthelevelofdrawdownneededduringdewatering operations. IntheapplicationofMODFLOW,thefollowingassumptionsweremade: Thereisnoconnectionbetweentheupperandloweraquiferintheareaofinterest. Drawdownbydewateringwillnotsignificantlyimpacttheassumedshallow groundwaterdividenorthofthesiteorthewaterlevelofthewetland. Thebottomsurfaceofupperaquiferisuniformat1400ftamsl. Thewetlandwaterelevationis1470ftamsl. Theproposedlandfillexpansionareabottomelevationis1460ftamsl,andtheareawill bedewateredasawhole(notinsubsections whichwouldfurtherreducethe dewateringestimate). MODFLOWwasruninsteadystatetogenerateestimatesofgroundwaterinflowratestothe underdrainsystem.ascreenshotofthegwvistasmodel,showingthegroundwater potentiometricsurface,draincelllocations,andgroundsurfaceelevationisincludedattheend ofthismemo.thefigurealsopresentsaneastwestcrosssectionofsurfaceelevationand groundwaterheadthroughtheproposedwastecell.theresultsofthesteadystaterunusing theparametersdescribedaboveindicateaninflowtotheproposedexpansionareaof0.5gpm. Ifhydraulicconductivityisvariedbyanorderofmagnitudeoneithersideoftheapplied geometricmean,theresultinginflowtotheexpansionexcavationmaybeaslowas0.16gpmor ashighas6.1gpm. RESULTS TheestimatedrateofaverageETlossfromthewetlandof580gpm(foropenwater evaporationalone)to870gpm(includinga50%increasefortranspiration)ismorethanthree ordersofmagnitudegreaterthantheestimateddewateringrateof0.5gpm.usingtheupper boundestimateof6.1gpm,theaverageetlossfromthewetlandisstilltwoordersof magnitudehigherthanthedewateringrate.basedontheseresults,anylossesingroundwater inflowtothewetlandfromdewateringoperationsareveryminorrelativetonaturaletlosses. Therefore,itisreasonabletopredictthatthedewateringoperationsplannedfortheproposed LyonCountyLandfillexpansionareaareunlikelytohaveanysignificantimpacttheBlack RushLakeWetland. IntegralConsultingInc.

53 LyonCountyLandfillDewateringSupport July3 rd,2007 Page6of7 REFERENCES Bedient,P.B.andW.C.Huber.1992.HydrologyandFloodplainAnalysis.SecondEdition. PrenticeHall.pp.692. Harbaugh,A.W.andM.G.McDonald.1996.UsersdocumentationforMODFLOW96,an updatetotheu.s.geologicalsurveymodularfinitedifferencegroundwaterflowmodel:u.s. GeologicalSurveyOpenFileReport96Ð485. Rumbaugh,J.O.,andD.B.Rumbaugh.2002.Guidetousinggroundwatervistas. EnvironmentalSimulations,Inc.(ESI),Reinholds,PA. SanchezCarrillo,S.,M.AlvarezCobelas,andM.Benitez.2001.Asimplemethodfor estimatingwaterlossbytranspirationinwetlands.hydrologicalsciences46(4), IntegralConsultingInc.

54 LyonCountyLandfillDewateringSupport July3 rd,2007 Page7of7 Ground Surface Elevation (ft amsl) Upper Edge of Waste Cell Drain Cells Groundwater Potentiometric Surface (ft amsl) ScreenshotofGWVistasshowinggroundwaterpotentiometricsurface,modeldrain locations,andgroundsurfaceelevation. IntegralConsultingInc.