Wastewater Facility Plan

Transcription

1 Village of Poplar Douglas County, Wisconsin Project No April 2009

2 Village of Poplar Douglas County, Wisconsin Project No Prepared by: MSA Professional Services, Inc. 301 West First Street, Suite 401 Duluth, MN, Phone: (218) April 2009 MSA Professional Services, Inc.

3 TABLE OF CONTENTS Page EXECUTIVE SUMMARY... i I. INTRODUCTION... 2 A. Background... 2 B. Purpose and Scope... 2 C. Planning Area... 3 D. Definitions and Abbreviations... 3 II. EXISTING CONDITIONS... 7 A. Geologic and Hydrogeologic Setting... 7 B. Economic Background... 7 C. Description of Existing Wastewater Collection System... 7 D. Description of Existing Wastewater Treatment Facilities... 8 E. Historical Wastewater Loadings... 9 III. INFILTRATION/INFLOW ANALYSIS A. Definitions B. Baseflow Determination C. EPA I/I Evaluation D. Infiltration/Inflow Determination E. Summary IV. PROJECTED CONDITIONS A. Population Forecasting B. Wastewater Loading Projections Future Residential/Commercial/Public Authority Flows Infiltration and Inflow C. Design Loadings V. STANDARDS AND GUIDELINES A. Existing WPDES Permit Requirements B. Future WPDES Permit Requirements VI. EVALUATION OF EXISTING WASTEWATER FACILITIES A. Wastewater Collection System Evaluation B. Wastewater Treatment Facility Process Evaluation VII. DESCRIPTION OF WASTEWATER TREATMENT ALTERNATIVES A. General No Action Regional Treatment Treatment and Groundwater Discharge Treatment and Land Application Treatment and Surface Water Discharge Summary of Feasible Wastewater Treatment Alternatives B. Alternative No. 1 Expand the Aerated Lagoon Facility C. Alternative No. 2: Addition of Rotating Biological Contactors D. Alternative No. 3: Moving Bed Biological Reactor (MBBR) April 2009 MSA Professional Services, Inc. G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

4 VIII. EVALUATION OF WASTEWATER TREATMENT ALTERNATIVES A. General Alternative No Alternative No Alternative No B. Cost-Effective Analysis C. Non-Monetary Differences Ease of Operation Treatment Performance Mechanical Reliability Ease of Construction Ease of Expansion D. Recommended Plan IX. ENVIRONMENTAL ASSESSMENT OF THE RECOMMENDED ALTERNATIVE 51 A. Land Use B. Water Resources C. Air Quality D. Noise E. Aesthetics F. Traffic G. Wildlife and Vegetation H. Social and Economic Impacts I. Historical J. Energy Consumption X. IMPLEMENTATION OF THE RECOMMENDED PLAN A. Summary Description of Recommended Plan B. Future Operator Requirements C. Public Participation D. Project Financing E. Project Implementation Schedule April 2009 MSA Professional Services, Inc. G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

5 LIST OF TABLES Table 2-1 Existing WWTF Flows and Loadings Table 3-1 Summary of I/I for the Village of Poplar Table 4-1 Population Estimates Table 4-2 Wastewater Flow Projections Table 4-3 Wastewater Mass Loading Projections Table 5-1 Existing WPDES Permit Requirements Table 5-2 Future WPDES Permit Requirements Table 6-1 Summary of Existing Lift Stations Table 8-1 Total Estimated Alternative Costs Table 8-2 Non-monetary Ranking of Alternatives Table 10-1 Proposed Project Schedule LIST OF FIGURES Figure 1-1 Village of Poplar Wastewater Facility Plan Area... 5 Figure 2-1 Overview of Wastewater Treatment Facility Figure 2-2 Summary of Influent Monthly Flow Data Figure 2-3 BOD and TSS Mass Loadings Figure 6-1 Wastewater Treatment Facility Effluent Monthly Average BOD Figure 6-2 Wastewater Treatment Facility Effluent Monthly Average TSS Figure 10-1 New Lagoon Location Appendix A Historical Flows and Loadings Appendix B WPDES Permit Appendix C WDNR Effluent Limits Memo Appendix D Alternative Cost Estimates LIST OF APPENDICES April 2009 MSA Professional Services, Inc. G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

6 Executive Summary EXECUTIVE SUMMARY The Village of Poplar, Wisconsin owns and operates a wastewater treatment facility that serves the Village of Poplar and the Northwestern High School. The wastewater collection system and treatment plant were constructed in As the treatment plant s average monthly flows began to approach the permitted 37,000 gpd level, and requests for additional connections were received from the Northwestern School System, the Village of Poplar contracted with MSA Professional Services for the preparation of a Facilities Plan. This Facilities Plan evaluated the future treatment needs of the Sanitary District and evaluated alternatives to determine the most cost-effective alternative for wastewater treatment. The selected alternative of adding an aerated covered lagoon and several other features at the WWTF will allow the Village to meet its wastewater treatment needs for the twenty year planning period. The estimated project cost of $1,302,500 includes the addition of a new lagoon for more treatment capacity, along with the addition of several items at the treatment plant to improve the current and future treatment efficiency. The Village of Poplar is slated to receive a design and construction grant from the US Army Corps of Engineers in the amount of $ 997,500, which is approximately 75% of the overall project cost. The Village is required to match the remaining 25% of the project cost, or $332,500. The Village has a preliminary agreement with the Northwestern School District to provide the required matching amount, and the affect on the existing users of the sanitary system is expected to be minimal. April 2009 MSA Professional Services, Inc. Page i G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

7 Section I Introduction I. INTRODUCTION A. Background The Village of Poplar, Wisconsin is located in northern corner of Douglas County. The Village owns and operates a wastewater treatment facility that serves the Village of Poplar and the Northwestern High School located to the east in the Town of Maple. The existing wastewater treatment facility is located in the SW ¼ of the SW ¼ of Section 33, T48N, R11W within the Village Limits. The wastewater collection system and treatment plant were constructed in As the treatment plant s average monthly flows began to approach the permitted 37,000 gpd level, and requests for additional connections were received from the Northwestern School System, the Village of Poplar contracted with MSA Professional Services for the preparation of a Facilities Plan. This Facilities Plan is being prepared to evaluate the future treatment needs of the Sanitary District and recommend a cost-effective alternative for wastewater treatment. B. Purpose and Scope The purpose of this Facilities Plan is to determine the most cost-effective and environmentally beneficial alternative with which the Village of Poplar can upgrade its treatment facilities to meet the Wisconsin Pollution Discharge Elimination System (WPDES) permit requirements under anticipated future loading conditions. The scope of this Facilities Plan Report is as follows: 1. To describe the Village of Poplar and the surrounding area, giving consideration to such factors as location, geology, soils, water resources, and economic background. 2. To characterize the existing wastewater flows in terms of both quantity and quality; and to estimate future wastewater flows over the next 20 years, giving consideration to the effects of increased service area, population, commercial and industrial growth. 3. To establish anticipated future WPDES permit requirements. 4. To evaluate the condition and effectiveness of the existing wastewater collection and treatment facilities, and identify deficiencies in the ability to meet future WPDES permit requirements. 5. To develop alternatives for wastewater treatment facilities to meet the future WPDES permit requirements for the anticipated wastewater flows. 6. To evaluate the alternatives with respect to their environmental impact and cost effectiveness. April 2009 MSA Professional Services, Inc. Page 2 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

8 Section I Introduction 7. To present a recommendation of the most cost-effective and environmentally sound plan for wastewater treatment for the Village of Poplar. 8. To recommend a timetable for implementation of the recommended plan. The planning process also includes an evaluation of wastewater flows and precipitation to determine if there is excessive inflow or infiltration of clearwater (rainwater or groundwater) being contributed to the wastewater treatment facility. C. Planning Area The planning area (2029 year service area) is shown in Figure 1-1 and includes all developed lands and developable lands that might be expected to be served by the Village s Wastewater Treatment Facility within the next 20 years. The planning area is comprised of land currently within the Village boundary, and a portion of land to the east which encompasses the Northwestern School Districts Elementary, Middle, and High Schools. The existing area which is serviced by the WWTF is also generally outlined. D. Definitions and Abbreviations Definitions of some terms used in this evaluation report are as follows: Biochemical Oxygen Demand Suspended Solids Biological Phosphorus Removal Chemical Phosphorus Removal Nitrification Denitrification Infiltration The biochemical oxygen demand (BOD) of domestic and industrial wastewater is the amount of molecular oxygen required to stabilize the decomposable matter present in water by aerobic biochemical action. Those solids that either float to the surface of, or are suspended in water, sewage, or industrial waste which are removable by a laboratory filtration device. The process of subjecting microorganisms to sequential anaerobic and aerobic conditions to facilitate the release and subsequent uptake of phosphorus in excess of cellular requirements. The process of adding chemicals to the waste stream to react with phosphorus and form an insoluble precipitate that can be removed through settling. The process of biologically oxidizing ammonia (NH + 4 /NH 3 ) to nitrate/nitrite (NO - 3 /NO - 2 ). The process of biologically converting nitrate/nitrite (NO - 3 /NO - 2 ) to nitrogen gas. The water entering a sewer system (including service connections) from the ground, through such means as, but not limited to, defective pipes, pipe joints, connections, or manhole walls. Infiltration does not include, and is distinguished from, inflow. April 2009 MSA Professional Services, Inc. Page 3 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

9 Infiltration/Inflow Inflow Excessive Infiltration/Inflow Present Worth Sanitary Sewer Sewer System Evaluation Storm Sewer Section I Introduction The total quantity of water from both infiltration and inflow without distinguishing the source. The water discharged into a sewer system (including service connections) from such sources as, but not limited to, roof drains, cellar, yard and area drains, foundation drains, cooling water discharges, drains from springs and swampy areas, manhole covers, cross connections from storm sewers and combined sewers, catch basins, storm water, surface runoff, street wash waters, or drainage. It does not include, and is distinguished from, infiltration. The quantity of infiltration/inflow which can be economically eliminated from a sewer system by rehabilitation as determined by a cost-effective analysis that compares the costs for correcting the infiltration/inflow conditions with the total costs for transportation and treatment of the infiltration/inflow. The total present worth method of evaluating sewage treatment systems involves bringing all costs of buildings, operating and maintaining the sewage treatment systems over a 20-year period to a total present worth in accordance with DNR guidelines. A sewer intended to carry only sanitary or sanitary and industrial wastewater, from residences, commercial buildings, industrial plants, and institutions. A systematic examination of the sewer system to determine the specific location, estimated flow rate, method of rehabilitation and cost of rehabilitation versus the cost of transportation and treatment for each defined source of infiltration/inflow. A sewer intended to carry only storm waters, surface run-off, street wash waters, and drainage. April 2009 MSA Professional Services, Inc. Page 4 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

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11 Section I Introduction Abbreviations of some terms used in this report are as follows: BOD 5 cfs CTH DNR EPA gpcd gpd gpm HRT I/I lb/day lb/cap/d mg mgd mg/l MLSS MLVSS MSA NH 4 -N NO 3 -N NWRPC STH SRT TKN TP TSS USH USACE WWTF five-day biochemical oxygen demand cubic feet per second county trunk highway Department of Natural Resources (State of Wisconsin) Environmental Protection Agency (Federal) gallons per capita per day gallons per day gallons per minute hydraulic retention time infiltration/inflow pounds per day (ppd) pounds per capita per day (ppcd) million gallons million gallons per day milligrams per liter mixed liquor suspended solids mixed liquor volatile suspended solids MSA Professional Services, Inc. ammonia nitrogen nitrate nitrogen Northwest Regional Planning Commission state highway solids retention time or sludge age total Kjeldahl nitrogen total phosphorus total suspended solids U.S. highway United States Army Corps of Engineers Wastewater Treatment Facility April 2009 MSA Professional Services, Inc. Page 6 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

12 Section II Existing Conditions II. EXISTING CONDITIONS A. Geologic and Hydrogeologic Setting The Village of Poplar encompasses approximately 7,616 acres, or approximately 12 square miles. Surface waters occupy approximately 6 acres of that area, with small streams draining to the north being the main bodies of water. The Village lies in an area of flat to gently sloping topography. Undeveloped areas consist primarily of light woods, natural wetlands and grass meadows. The geography of the area is dominated by glacial deposits, and the Village of Poplar is near the southern edge of the Superior Lowland. Soils in the area are dominated by the Douglas and Hanson Creek Members of the Miller Creek Formation. Both of the Douglas and Hanson Creek Members are predominantly clay (45 to 85%), silt (20 to 40%), and sand, loams and clays (3 to 20%). The Village lies within the Lake Superior Watershed. Depth to groundwater is generally greater than 50 ft in this area, however; many wells must be extended into the underlying bedrock at depths exceeding 200 ft to be able to produce a sustainable volume of water. Based on the surface topography, the groundwater flow direction in the vicinity of the existing wastewater treatment facility appears to be to the North. B. Economic Background Detailed employment profiles are not available for the Village of Poplar, however; it is expected that the employment profiles follow that of Douglas County as a whole. The Northwestern Regional Planning Commission and the Wisconsin Department of Workforce Development indicates that majority of people within the County are employed in one of the following four occupations: Trade, Transportation, Utilities (30.1%); Educational & Health (21.9%); Leisure & Hospitality (14.7%); Manufacturing (8.0%), Public Administration (8.0%), Professional and Business Services (5.2%), and construction (5.2%). There is a seasonal tourist industry in the areas surrounding the Village of Poplar due to Amnicon Falls State Park to the west, and the Brule River State Forest to the east. Based on the 2000 US census data, the median household income in the Village is $41,406. The average household size was 2.60 according to the 2000 census data. The Village s low to moderate income (LMI) score is 33.2% based upon the 2000 census. C. Description of Existing Wastewater Collection System The wastewater collection system in the Village of Poplar is comprised of gravity sewer mains, force mains and lift stations. At present there are four lift stations within the Village, and one lift station located at Northwestern High School to the east. There is approximately 39,500 ft of 8-inch gravity sewers constructed of PVC, and approximately 120 manholes associated with the gravity sewer sections of the collection system. In April 2009 MSA Professional Services, Inc. Page 7 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

13 Section II Existing Conditions addition to the gravity sewers, there is approximately 1,800 ft of 2-inch forcemain, 4,300 ft of 4-inch forcemain, and 16,600 ft of 6-inch forcemain. The gravity sewer sections are all 8-inch diameter, and the approximate average depth exceeds 12 ft below grade. The forcemain sections are all 7.0 to 8.0 ft below grade. The lift stations and the treatment facility locations are shown on Figure 1-1. D. Description of Existing Wastewater Treatment Facilities The Village of Poplar currently uses a series of lagoons to treat its wastewater. The lagoon system uses natural bacterial and other organisms in the wastewater to remove the dissolved organic matter. Mechanical blowers and mixers provide aeration to the bacteria in the lagoons to accelerate treatment. Following treatment, treated effluent is continuously discharged to a small tributary of Bardon Creek. The treatment facility and collection system was originally constructed in The 1998 design flow was 37,000 gpd. Figure 2-1 shows an overview of the wastewater treatment facility. The treatment components include three lagoons arranged in series and a polishing reactor. An influent manhole is used as a main discharge point for the forcemain which feeds the wastewater to the plant, and as a sampling point for the influent. Lagoon No. 1 has a total volume of 456,000 gallons, and is divided equally into Cells 1 and 2, which are separated by a baffle curtain. Cells 1 and 2 are completely mixed via aerators/mixers, and covered with an insulated cover to retain the latent wastewater heat to maximize treatment. Cell No. 3 (Lagoon No. 2) has a total volume of 284,000 gallons and is a covered partially mixed and aerated lagoon. Cell No.4 (Lagoon No. 3) has a total volume of 345,000 gallons is intended as a settling lagoon and is not equipped with mixing or aeration, but it is covered and provides for settling of the wastewater. All of the lagoons are equipped with a PVC liner. A fixed film polishing reactor downstream of Cell No. 4 provides for additional treatment to the effluent prior to discharge. A manhole downstream of the polishing reactor serves as an effluent monitoring point prior to the effluent being discharge by gravity to a small stream which is a tributary of Bardon Creek. The WWTF did accept holding tank waste from October 2004 through February The yearly totals for this hauled waste were less than 200,000 gallons/year for 2004 through Sludge has settled in the lagoons since the facility began operation in 1998, and the additional holding tank waste did contribute to more solids entering and settling within the lagoons. In 2006 the sludge in Lagoon No. 3 (Cell No. 4) was measured and the depths varied from 4.0 to 5.0 feet near the outlet pipe. Approximately 10,000 gallons of sludge (total) was removed in August and October of Poor effluent quality due to solids carryover into the effluent caused the district to have several loads of sludge removed from the Cell No. 4 again in The 2008 sludge removal focused on the area near the outlet pipe of Cell No. 4, and the approximately 6000 gallons (total) was removed in The sludge removed in 2007 and 2008 was disposed of at the City of Superior WWTF. The Poplar WWTF has begun to limit the amount of holding tank waste due to the effect on effluent quality. April 2009 MSA Professional Services, Inc. Page 8 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

14 Section II Existing Conditions Influent wastewater samples are collected with a 24-hour composite sampler from the influent manhole. The influent sampler is located in a small building which houses the main electrical distribution center, flowmeter recoding charts, and storage. Effluent wastewater samples are collected with a 24-hour composite sampler after the effluent polishing reactor at the effluent manhole. The sampler is located in a second small building which houses the aeration blowers. The 1998 design annual average flow for the existing facility is 37,000 gpd, and the corresponding monthly maximum flow is 69,000 gpd. The effluent is discharged to the unnamed tributary to Bardon Creek which is classified as a limited aquatic life (marginal surface water). Bardon Creek is classified as limited forage fish (intermediate surface water). E. Historical Wastewater Loadings A summary of the influent monthly flow data from January 2005 to October 2008 is shown graphically on Figure 2-2. A complete list of the monthly flow and organic loading data is included in Appendix A. The average influent flow during this period was 34,500 gallons per day. The peak monthly flow was 68,100 gallons per day, and the peak daily flow has exceeded 100,000 gpd on several occasions during the review period. The influent wastewater is primarily domestic and commercial in nature. A small amount of industrial flows from the General Mills plant were primarily derived from domestic wastewater sources. The commercial flows from small businesses and the local school district are also from primarily domestic wastewater sources. The current flows from the high school are included in the current BOD and TSS loadings. The historic BOD and TSS concentrations from January 2005 to October 2008 averaged 192 mg/l, and 169 mg/l respectively, and the BOD and TSS loadings were 53.7 lbs BOD/day (0.15 lbs BOD/capita-day) and 48.7 lbs BOD/day (0.13 lbs BOD/capita-day). These loadings exclude the months from June 2007 through March 2008 due to questionable composite samples. The values are slightly lower than would be expected for domestic wastewater. The average influent BOD concentration for the entire period from January 2005 to October 2008 was 352 mg/l, however this period includes anomalous high influent values during June 2007 to March The influent composite sampler had been set to take a 24-hr composite sample on Monday of each week, and this sample was being highly influenced by a relatively small amount of washdown water from the General Mills plant that only occurred on weekends, typically Sunday evening. The 1,500 gallons of washdown water would take several hours to reach the WWTF due to this flow being routed through two lift stations. The Monday sampling was changed to Tuesday of each week in March The influent BOD and TSS returned back to levels that were similar to the previous values from previous years. A summary of the influent monthly average Flow, BOD, and TSS data from January 2005 to October 2008 is provided in Appendix A. April 2009 MSA Professional Services, Inc. Page 9 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

15 Section II Existing Conditions The Village does have small commercial and industrial users. The commercial users such as churches, small stores, and banks only have wastewater generated from the sanitary facilities, and the water use is based upon the number of employees. The only industrial user over the January 2005 to October 2008 review period was a General Mills plant. Based on previous Village flow monitoring, the average daily flow from the General Mills plant was estimated at 1,500 gpd. This average includes a weekly washdown event of 1,500 gallons. The General Mills plant shut down in September 2008 and there are no wastewater flows from this source currently. Figure 2-3 depicts the BOD and TSS mass loadings over the review period. Since the General Mills plant shut down in September 2008, this anomalous effect is not expected to be a factor in future loadings. The average influent concentration for selected nitrogen species is limited. Some influent and effluent sampling for ammonia was conducted in 2003, and the range of influent ammonia was 10.3 to 31.5 mg/l. No influent Phosphorus data is available. Table 2-1 summarizes the current flows and loadings at the Poplar WWTF. Table 2-1 Existing WWTF Flows and Loadings Item Existing Flows and Loadings (1) Annual Average Influent Flow, gpd 34,500 Peak Month Influent Flow, gpd 68,100 Peak Day Influent Flow, gpd 250,000 Average Daily BOD Loading, lbs/d 53.7 (2) Peak Month BOD Loading, lbs/d 87.9 (2) Average Daily TSS Loading, lbs/d 48.7 (2) Peak Month TSS Loading, lbs/d 95.6 (2) (1) Based on WWTF data from January 2005 through October (2) Excludes period from June 2007 through March 2008 April 2009 MSA Professional Services, Inc. Page 10 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

16 INFLUENT MANHOLE SAMPLE POINT 701 POLISHING REACTOR CELL 2 CELL 1 CELL 3 CELL 4 EFFLUENT MANHOLE SAMPLE POINT 001 LINES AND DIMENSIONS ARE APPROXIMATE Prepared by Randy Jones Douglas County GIS Mapping Department VILLAGE OF POPLAR WASTEWATER TREATMENT FACILITY MAY 2007 AERIAL PHOTO Feet inch equals 100 feet ±

17 Figure 2-2 Monthly Average Wastewater Flow, Poplar, WI Influent Flow (mgd) Jan-05 Apr-05 Jul-05 Oct-05 Jan-06 Apr-06 Jul-06 Oct-06 Jan-07 Apr-07 Jul-07 Oct-07 Jan-08 Apr-08 Jul-08 Average Monthly Flow

18 Sep Figure 2-3 Average Monthly BOD & TSS Loadings, Poplar, WI Mar-05 May-05 Jul-05 Sep-05 Nov-05 Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Mar-07 May-07 Jul-07 Sep-07 Nov-07 Jan-08 Mar-08 May-08 Jul-08 Month/Year Average Monthly BOD Average Monthly TSS Jan-05 Loading, lbs/d

19 Section III Infiltration/Inflow Analysis III. INFILTRATION/INFLOW ANALYSIS A. Definitions An evaluation of infiltration and inflow into the Village of Poplars wastewater collection system is a required step during the facilities planning process. The infiltration/inflow (I/I) analysis was conducted to establish the quantity of clear water entering the collection system and to determine whether this quantity is significant enough to warrant further investigation. The further investigation, if warranted, would consist of a more systematic examination of the sewer system to determine specific infiltration and inflow locations, estimate flows, and estimate the cost of rehabilitation versus the cost of transportation and treatment for each defined source of infiltration and inflow. Infiltration is defined as the water entering a sewer system (including service connections) from the ground, through such means as, but not limited to, defective pipes, pipe joints, connections, or manhole walls. Infiltration does not include, and is distinguished from, inflow. Inflow is defined as the water discharged into a sewer system (including service connections) from such sources as, but not limited to roof drains, cellar, yard and area drains, foundation drains, cooling water discharges, drains from springs and swampy areas, manhole covers, cross connections from storm sewers and combined sewers, catch basins, storm water, surface runoff, street wash waters, or drainage. It does not include, and is distinguished from, infiltration. Infiltration can be estimated as the difference between average daily water use and the average daily wastewater flow. Infiltration can further be broken down into dry weather and wet weather infiltration. Infiltration/Inflow (I/I) includes the total quantity of water from both infiltration and inflow without distinguishing the source. The EPA defines excessive I/I as that which can economically be reduced by improvements to the collection system. Over the past years the EPA has developed several documents providing guidance in determining whether I/I is excessive. B. Baseflow Determination Annual water use records are not available for the Village since all of the users are on private wells. The typical water usage per capita can be estimated using DNR guidance, and typically ranges from 60 to 70 gallons per capita per day (gpcd). April 2009 MSA Professional Services, Inc. Page 14 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

20 Section III Infiltration/Inflow Analysis The Village of Poplar s average daily potable water use is estimated to range from 21,800 to 25,400 gpd based on 363 people connected within the service area and using a wastewater generation rate of 60 to 70 gpcd. The midpoint of this range (65 gpcd) was used as a basis for estimating the baseflow at 23,600 gpd. The annual average industrial flow was 1,500 gpd, and the daily average flow from the high school of 2,100 gpd. Subtracting out the industrial and school flows results in an average daily residential flow of 30,900 gpd based on the annual average flow of 34,500 gpd. Subtracting out the residential/commercial baseflow of 23,600 gpd results in an I/I flow of 7,300 gpd. The high school has it own designated pump station and forcemain to the WWTF, and this source is treated similar to an industrial flow for calculating I/I. The average daily I/I per capita is 20.1 gpcd based on a service area population of 363 and the average daily I/I of 7,300 gpd. Precipitation data used in the I/I evaluation is from the NOAA station in Superior, WI. C. EPA I/I Evaluation 1. The EPA publication Evaluation of Infiltration/Inflow Program (EPA ) found that rehabilitation of sanitary sewer systems exhibiting a maximum 7 day average wet weather I/I flow less than 6,000 gallons of I/I flow per day per inch-mile of collection pipe is not cost effective. The existing sanitary sewer system in the Village of Poplar includes approximately 39,000 feet of 8-inch diameter sanitary sewer. The total inch-miles of sanitary sewer within the district's system is 8 x 39,500 5,280 = 59.8 inch-miles. Based on this total and the EPA criteria of 6,000 gpd per inch-mile, the total amount of I/I that would be considered non-excessive for the collection system is 358,800 gpd. The maximum 7-day average wet weather flow for the January 2005 to October 2008 review period occurred from March through March 15, During this 7 day period, the average influent flow to the plant was 95,700 gpd. Subtracting the estimated wastewater baseflow flow of 23,600 gpd and the industrial flow of 1,500 gpd gives a maximum 7-day total I/I flow of 70,600 gpd. The high school was not connected to the system in March 2007, thus its average flow was not subtracted out. Comparing this value to the EPA allowable I/I of 358,800 gpd shows that I/I is well below the acceptable limit. 2. The EPA handbook entitled Sewer System Infrastructure Analysis and Rehabilitation (EPA 625/9-91/030) states that infiltration is non-excessive if the 7-14 day average dry weather domestic wastewater flow does not exceed 120 gpcd during periods of high groundwater. The dry weather infiltration during periods of high groundwater is estimated using data from months when the groundwater was presumably high due to over 2-inches of rain in the previous month, and/or the spring snowmelt. The table below lists four periods over the 2005 through September 2008 flow review period that each had over April 2009 MSA Professional Services, Inc. Page 15 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

21 Section III Infiltration/Inflow Analysis 2-inches of rainfall in the previous month, and no measurable precipitation during the 7 to 14 day review timeframe following the rainfall period. Flow Period Average Flow (gpd) Prior Precipitation 4/1/07-4/14/07 50, in previous month & snowmelt 10/6/05-10/12/05 35, in previous month 5/27/05-6/3/05 32, in previous month 5/18/08 5/24/08 29, in previous month The historic peak 14-day flow of 50,900 gpd occurred in April When the industrial average daily flow of 1,500 gpd is subtracted out, the per capita flow rate was 49,400/363 = 136 gpcd. The high school was not connected to the system in April 2007, thus its average flow was not subtracted out. The per capita rate is lower for the other three events listed (89, 80, and 70 gpcd). While the April 2007 value was above the EPA threshold of 120 gpcd, no other peak 7 or 14-day average flows were higher than 100 gpcd. It appears that April day average flow was an isolated flow event, and although no rainfall was reported during the period, the NOAA weather station in Superior may have missed an isolated event in the Village of Poplar approximately 15 miles away. Since no other 7 to 14-day flow event is within 30% of the April 2007 period in question, it is reasonable that this event may be associated with leaking manholes that were repaired in The October 2005 flow event yields a per capita flow of 89 gpd during periods of high groundwater and no rainfall. This value is considered most representative of the Village of Poplar s sewer system. 3. The EPA handbook entitled Sewer System Infrastructure Analysis and Rehabilitation (EPA 625/9-91/030) states that total I/I is non-excessive if the total daily flow during a storm is less than or equal to 275 gpcd. The Village of Poplar s connected users was estimated at 363 people. Based upon this estimated population, I/I would be non-excessive if the maximum daily flow is less than 99,800 gpd. As the estimated number of users varies slightly over the review period, a threshold influent flow of 100,000 gpd was used as an initial level to sort the data. April 2009 MSA Professional Services, Inc. Page 16 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

22 Section III Infiltration/Inflow Analysis The peak daily flows were reviewed over the period January 2005 through October Over the 3+ year period there were 19 days when the influent flow exceeded the 100,000 gpd criteria value. Many of these flow events represent a single day when the flow was above 100,000 gpd, but less than 110,000 gpd. To isolate the excessive I/I events, the prior and post day s flows were reviewed for each of the periods, and the number of significant events is reduced to four periods, each is listed below. Date October 4, 2005 October 5, 2005 March 12, 2007 March 13, 2007 April 26, 2008 May 3, 2008 Daily Flow 144,000 gpd 250,000 gpd 192,000 gpd 155,000 gpd 184,000 gpd 204,000 gpd An evaluation of the rain events during October 2005 shows 7.34-inches of rain over the 10/3 to 10/5/05 period, and over 10-inches of rain within the previous 21 days. This event resulted in a short lived flow spike as the plant influent flow dropped to 77,000 gpd the following day, and down to 19,000 gpd by 10/7/05. The March 2007 event is due to the rapid snowmelt and frost leaving the ground as only a trace of precipitation was reported on the previous day. This event also resulted in a short lived flow event and the plant influent flow dropped to 75,000 gpd the following day, and down to 36,000 gpd by 3/15/07. The April 16 and May 2, 2008 events are associated with over 4-inches of rainfall during the period from April 19 to May 3, As is the case with the other high flow events, the plant influent flow dropped to less than 80,000 gpd the following day, and to less than 50,000 gpd by the second day following the peak flow event. Several manholes were repaired after this flow event, and it is highly likely that these specific sources contributed a large portion of I/I to the system prior to the repairs. The 275 gpcd allowable limit under the EPA Criteria for peak day I/I is generally only exceeded during periods of high groundwater and rainfall events. Flows at the WWTF increase in the late winter and early spring of each year, prior to major rain events, and are associated with the snowmelt and saturated soil conditions. Precipitation events of over 2-inches during the summer months typically raise influent flows less than 5,000 gpd versus an increase of up to 200,000 gpd for spring flows. This evidence indicates that both high groundwater and saturated surface soils are required for a major I/I event. This is reasonable when the installation of sewers requires 6 to 12-inches of free-draining sand within the pipe envelope, and with the massive clay soils in the area, the sewer bedding can act as a drain for groundwater. As infiltration is notoriously difficult and expensive to locate and eliminate (compared to locating and eliminating inflow sources) it would not appear to be cost effective to pursue the infiltration that occurs in Poplar. April 2009 MSA Professional Services, Inc. Page 17 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

23 Section III Infiltration/Inflow Analysis To achieve the 275 gpcd criterion would require limiting the total day flow (including industrial and commercial base flows) to approximately 100,000 gpd. Based upon a review of daily flows from January 2005 through October 2008, only 19 days out of 1,400 days had flows exceeding 100,000 gpd (1.4 percent). Based on replacing approximately 10 percent of the sewers (4,000 feet) at $65/LF and adding I/I investigation, design, and administration costs, it is likely that a minimum of $350,000 would be spent trying to reduce flows that occur only 1.4% of the time. There is also no guarantee that the new sewers would function better that the existing PVC sewers which are only 10-years old and constructed to modern standards. Pump station run-time records indicate that the I/I is system wide, and there is no indication that certain areas or basins are contributing more I/I than others. Observations made during wet weather indicates that leaking manholes are a significant part of the I/I contribution, and the Village has already began the manhole rehabilitation process. The Village has been proactive in identifying and repairing I/I sources. After the 2005 yearly flows were reviewed by the Village, Village staff conducted manhole inspections during a wet weather period in All of the sanitary sewer system manholes, approximate 120 in total, were inspected and documented during this work. The Village staff has indicated that once the snow has melted, and the manholes can be inspected, it is typical to find some manholes each spring that were shifted due to snow plowing activities. These repairs are generally made as the leaking manholes are located. In 2007, ten manholes were repaired by installing new boots at the pipe connection points. During the late summer of 2008 three manholes were repaired by sealing the joints with poly injection. The Village of Poplar does have a continuing program of identifying susceptible areas and making repairs. The location of many of the manholes along roadways and adjacent to drainage ditches is considered to be the highest potential I/I source for the system. As the Village continues to identify and actively address these situations, the future peak flows are expected to be minimized. D. Infiltration/Inflow Determination Using existing flow data and the methodology presented above in the EPA I/I analysis, I/I quantities can be estimated for various I/I flow conditions. The values are summarized in the following paragraphs. 1. Annual Average I/I. The average annual flow at the WWTF for the period January 2005 through October 2008 was 30,900 gpd once the industrial and high school flow is subtracted out. The base flow as estimated by 65 gpcd and 363 users is 23,600 gpd. Thus, the annual average I/I is equal to 30,900 23,600 = 7,300 gpd. The average annual I/I per capita is 7,300 gpd divided by the 363 current connected population, or 20.1 gpcd. April 2009 MSA Professional Services, Inc. Page 18 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

24 Section III Infiltration/Inflow Analysis 2. Peak Dry Weather Infiltration. The peak dry weather infiltration can be determined by subtracting the average annual base flow from the 7-day peak dry weather flow. Using the 7-day average flow rate during periods of high groundwater of 35,800 gpd, (see Part 2 of the EPA I/I Evaluation) the average base flow of 23,600 gpd, and the estimated industrial daily flow of 1,500 gpd, the estimated average dry weather I/I can be calculated to be 10,700 gpd. The high school was not connected to the system in October 2005, thus its average flow was not subtracted out. This value is more indicative of infiltration during periods of high groundwater. The peak dry weather I/I per capita is 10,700 gpd divided by the 363 current connected population, or 29.5 gpcd. 3. Peak Wet Weather I/I. Using the maximum 7-day wet weather flow of 95,700 gpd (see Part 1 of EPA I/I Evaluation) and the estimated wastewater base flow of 23,600 gpd, the peak weekly wet weather I/I can be calculated to be 95,700 23,600 = 72,100 gpd. Using this flow, the estimated industrial daily flow of 1,500 gpd, the average high school flow of 2,100 gpd, and the estimated base flow of 23,600 gpd, the peak month I/I can be calculated to be 95,700 1,500-2,100-23,600 = 68,500 gpd. The peak wet weather I/I per capita is 68,500 gpd divided by the 363 current connected population, or 189 gpcd. 4. Peak Month I/I. The peak month flow over the January 2005 through October 2008 period was 68,100 gpd in April Using this flow, the estimated industrial daily flow of 1,500 gpd, the average high school flow of 2,100 gpd, and the estimated base flow of 23,600 gpd, the peak month I/I can be calculated to be 68,100 1,500-2,100-23,600 = 40,900 gpd. The peak month I/I per capita is 40,900 gpd divided by the 363 current connected population, or 113 gpcd. Peak Day I/I. The highest peak daily flow associated with a rain event was on October 5, 2005 when a total daily flow of 250,000 gpd was recorded. As discussed previously, several system repairs have already reduced the peak daily flows. To determine an appropriate peak day I/I value for the future conditions, the 3-day average flow was used as it is more indicative of the sewer systems future performance. The total of five lift stations can also intensify an individual day s peak flow depending upon pumping cycles and cumulative flow values resetting at a given time each day. The October 2005 event also shows the highest peak 3-day flow of any period from January 2005 through October The peak day I/I is calculated as 157,000 23,600 (baseflow) 1,500 (industrial) = 131,900 gpd. The high school was not connected to the system in October 2005, thus its average flow was not subtracted out. The peak day I/I per capita is 131,900 gpd divided by the 363 current connected population, or 363 gpcd. While this value does exceed the recommended EPA threshold of 275 gpcd, many system repairs have been made since this event, and the 275 gpcd represents a threshold for larger systems. The peak daily flows and the 3-day average flows for a given peak day flow event have generally decreased since The Villages April 2009 MSA Professional Services, Inc. Page 19 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

25 Section III Infiltration/Inflow Analysis E. Summary proactive approach to locating and eliminating I/I sources is expected to continually reduce the amount of I/I entering the system. The rural setting also contributes to the higher per capita peak flow due to the relatively long length of sewer needed for each connection. The EPA threshold includes many urban and more densely populated sewer service areas which reduces the effective I/I per capita, and should be used with caution when determining cost-effective I/I reduction efforts. The EPA Criteria is sensitive to the density of people per mile of sewer and can be biased when applied to smaller Villages. To illustrate the special situation in Poplar, a population per mile of pipe should be considered. Poplar has 7.5 miles of sewer pipe serving only 363 people. This results in 48 people per mile. This value may be compared with that of a larger community, such as Tomahawk, Wisconsin, where 9.8 miles of pipe serves 3,357 people, resulting in 341 people per mile. This value shows how the per capita values are biased against a small community such as Poplar. A summary of the I/I evaluations for the Village of Poplar is shown in Table 3-1. The I/I in the Village s collection system is below most of the EPA threshold criteria. The Village has reviewed the system for areas of excessive I/I, and identified and repaired several I/I sources. Based on the levels of I/I, and the continuing effort of yearly repairs, further investigation is not cost effective at this time. Table 3-1 Summary of I/I for the Village of Poplar Annual Average I/I 7,300 gpd 20.1 gpcd Peak 7-Day Dry Weather I/I 10,700 gpd 29.5 gpcd Peak 7-Day Wet Weather I/I 68,500 gpd 189 gpcd Peak Month I/I 40,900 gpd 113 gpcd Peak Day I/I 131,900 gpd 363 gpcd While the total I/I within the collection system is not considered excessive, it is recommended that Village continue to identify and remove potential I/I sources. Many repairs have been made to the system since these peak flow events occurred. The peak day I/I levels listed only occur when an extreme combination of rainfall and/or snowmelt is combined with an elevated water table. The Village of Poplar s system was constructed in 1998 to modern standards, and the relatively excessive length of sewer per user makes large scale rehabilitation efforts less cost effective. The Village is continuing to locate and repair I/I sources each year, and the I/I values are expected to decrease as this program continues. April 2009 MSA Professional Services, Inc. Page 20 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

26 Section III Infiltration/Inflow Analysis Based on these considerations, further investigation of I/I for the Village of Poplar is not considered cost effective at this time. The Village should continue to take advantage of opportunities to address obvious significant sources of inflow or infiltration as these opportunities arise. The Village is already rehabilitating manholes which seem to be susceptible to I/I. The recommended EPA criteria is also based upon a combination of both rural and urban systems, thus a rural system such as the Village of Poplar s would be expected to show higher per capita peak flows since the number of users per length of sewer is much lower than the average system in the U.S. April 2009 MSA Professional Services, Inc. Page 21 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc

27 Section IV Projected Conditions IV. PROJECTED CONDITIONS A. Population Forecasting The existing WWTF currently serves approximately 66 percent of the people living in Poplar (~ 363 people), the Northwestern School District High School, and one in-active industrial complex (General Mills). The WWTF is expected to serve additional people within the Village of Poplar, additional schools in the Northwestern School District, and the ability to serve the former General Mills industrial complex. In order to develop projected population estimates for the Village, historical census data and population projections by the Wisconsin Department of Administration (DOA), the Northwest Regional Planning Commission (NWRPC), and the Draft Douglas County/Village of Poplar Comprehensive Plan were evaluated. In practice, the NWRPC and the Comprehensive plans reference the DOA projection such that there is really one set of population projections. These projections were used as an initial base and then adjusted to reflect specific future growth expectations for the Northwestern School District, service area expansions near the Town of Maple, and growth within the Village service area. Table 4-1 summarizes the historic census data and the DOA projections for the Village of Poplar up to Year Table 4-1 Population Estimates Year Historical Population (U.S. Census) DOA/NWRPC Population Projections The DOA/NWRPC population projections indicate a 30-year growth rate of 8.5% (~1.6 persons per year). However, it is expected that the growth within the WWTF service area will have a greater growth rate than the Village as a whole. It is expected that the growth rate in the Village portion of the service area will be higher than the DOA/NWRPC projections and be in the range of surrounding areas such as Amnicon (22.2%) and Lakeside (13.8%). One of the reasons for a higher expected growth rate is the proximity to the Town of Maple as explained below. April 2009 MSA Professional Services, Inc. Page 22 G:\Projects\7700s\7750s\7752\ Poplar WWTF Plan\Documents\ PoplarFacilityPlanRpt\Facility Plan April Rev1.doc