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Letter Water Supply Distibution Update BonestrooBon croo Rosene Anderlik & Associates Engineers & Architects November 9, 2004 City of Cottage Grove Public Works Department 8635 Point Douglas Road Cottage Grove, MN 55016 Attn: Ms. Jennifer Levitt Bonestroo, Rosene, Anderlik and Associates, Inc. is an Affirmative A 'Equal Opportunity Employer and Employee Owned Principals: Otto G. Bonestroo, P.E. • Marvin L. Sorvala, P.E. • Glenn R. Cook, P.E. • Robert G. Schunicht, PE. Jerry A. Bourdon, P.E. • Mark A. Hanson, P.E. Senior Consultants: Robert W Rosene, P.E. Joseph C. Anderlik, P.E. Richard E. Turner, P.E. Susan M. Eberlin, C.P.A. Associate Principals: Keith A. Gordon, P.E. Robert R. Pfefferle, P.E. • Richard W. Foster, PE. • David O. Loskota, P.E. Michael T. Rautmann, RE. • Ted K. Field, P.E. Kenneth P Anderson, PE. • Mark R. Rolfs, RE. • David A. Bonestroo, M.B.A. Sidney P Williamson, PE., L.S. • Agnes M. Ring, M.B.A. • Allan Rick Schmidt, PE. • Thomas W. Peterson, PE. James R. Maland, P.E. Miles B. Jensen, P.E. L. Phillip Gravel III, P.E. • Daniel J. Edgerton, PE. • Ismael Martinez, P.E. Thomas A. Syfko, PE. Sheldon J. Johnson • Dale A. Grove, PE. • Thomas A. Roushar, RE. • Robert J. Devery, PE. Offices: SL Paul, St. Cloud, Rochester and Willmar, MN • Milwaukee, WI • Chicago, IL Website: wwwbonestroo_com Re: Water Supply and Distribution Plan Update Dear Jennifer: As requested, we have put together a work plan to update the 1995 Water Supply and Distribution Plan. This letter outlines the major issues and provides a work plan to update the plan. Where appropriate, we have listed work that City staff will perform. Major Issues There are three major issues for the Water Supply and Distribution Plan to evaluate: growth, phasing, and financing of proposed improvements. Growth: The basic purpose of the Water Supply and Distribution Plan Update is to provide a guide to orderly expansion of the trunk water system to handle the projected growth of the City. Changes in the development patterns and land use have reduced the projected 2020 and ultimate population from the estimates in the 1995 plan. Additionally, the East Ravine Community Pre - design Study has looked at land use and development phasing for the east ravine area. We will build on that plan, and look at the impact of growth beyond the East Ravine Study Area — out to the City limits. Phasing: The East Ravine Community Pre - design Study is evaluating phasing of development for the East Ravine. We will use this phasing plan, as well as current City planning for the remainder of the City to prepare a water system capital improvement plan for the entire City. Additionally, we will identify key "triggers" for implementing water system improvements, so that the City can better plan when to start each facility, and can update the CIP based on actual growth. 2335 West Highway 36 ■ St. Paul, MN 55113 ■ 651-636 -4600 ■ Fax: 651 -636 -1311 Cite of Cottage Grove November 10, 2004 Page 2 • Financing of Proposed Improvements: The study will update the cost recovery system based on the latest cost estimates for the ultimate water system, and the latest estimates for future connections and developable acres. Basic Work Plan An outline of the tasks required to update the 1995 Water Supply and Distribution Plan is presented below. We anticipate the City will prepare Land Use and water distribution system maps on their GIS system. These maps will be delivered electronically for Bonestroo use during the study. City staff will use the Land Use Map and GIS to calculate population projections and the developable acres of each land use for each analysis period (2025 and Ultimate). The City will also help collect data, perform hydrant testing, and attend meetings with Bonestroo staff. Basic Work Plan tasks are outlined below. Task 1: Project Initiation and Data Collection We will review data and information collected for the 1995 Water Supply and Distribution Plan and supplement that data with information and data for facilities constructed since the 1995 Plan publication. Additionally, we will meet with Cottage Grove staff to get input on any changes, modifications, or improvements that they would like to see in the water system. Task 2: Water Usage Review and Projections We will obtain and review water use data collected since the 1995 Plan in order to establish existing and estimate future water use patterns within the City. We will establish water use at points throughout the City based on the updated land use plan. Design average day and maximum day water demands will be established for the years 2025 and the ultimate build out of the City. Maximum Fire flow requirements will be reviewed based on Insurance Services Office and City requirements. We will meet with the City (at the Project Initiation Meeting) to review the projected water demands and fire flow requirements. For this task, we anticipate that the City will summarize water use (average and maximum day use for the Grove, Estates, and High Zone), provide a copy of the latest ISO Report, and provide a representative from the Fire Department at the meeting. The City will also use the GIS system to calculate developable acres by land use type for each of the junction nodes created for the computer model. Task 3: Wellfield Review We will review the wellfield plan to ensure it meets the needs of the City's revised ultimate water demand. This analysis will consist of estimating the number of additional wells required (based on capacity of existing wells and the results of North Wellfield Study done by Bonestroo last year). City of Cottage Grove November 10, 2004 Page 3 Task 4: Water Treatment Evaluation We will review the existing well water quality with respect to current and proposed drinking water standards. This evaluation will include both public health concerns and aesthetic issues, such as taste, odors, and "red" or "black" water complaints. The City will provide recent water quality tests for every well. Task 5: Hydraulic Modeling The existing hydraulic model of the Cottage Grove Water System will be upgraded to a WaterCAD model. WaterCAD is a powerful analytical tool that operates in a totally integrated AutoCAD and GIS environment. The computer model can be viewed with City base maps, land use maps, or integrated into the City GIS system. By simulating operation of the water system, the computer model: • Reveals system problems, • Predicts the effects of alternative solutions, and • Predicts the effects of system expansions. Pipes constructed since the 1995 plan will be added to the model, and the model will be used to size future trunk water mains to serve development as well as address these near - term concerns: ✓ Determine the need for and location of Industrial Park storage, ✓ Drive -In Theater site treatment and storage, • Determine need for water tower in the Grove area, and • Size and location for connection between Pinehill Tower and the Grove Area. Task 6: Capital Improvement Plan A water utility must have a sound basis for planning the expansion of its water system. This is especially true now, with increasing regulations regarding property acquisition, public notification and construction. A sound Capital Improvement Plan (CIP) will enable Cottage Grove to have the required facilities in -place by the time they are needed. The CIP will be prepared for the trunk water system. The CIP will be in one -year increments through 2010, in five -year increments through 2025, and will consider remaining improvements to be post -2025. The CIP will be based on the best available projections from the City for population, land use, and water use. Additionally, the CIP will be linked to benchmark events to allow Cottage Grove to update the CIP easily. For example, wells and water towers will be tied to water use thresholds. Distribution system improvements will be linked to future development or to coincide with street reconstruction projects. City of Collage Grove November 10, 2004 Page 4 Task 7: Economic Analysis The operation of a water utility must have a sound financial basis. Planning -level cost estimates for all of the proposed trunk water system facilities will be prepared and presented in the report. An estimate of the land required for wells and water towers will be provided so that an estimated cost for land acquisition can be included in the cost of each facility. The City will provide land costs. These costs will be included in the CIP described above. Based on the overall cost of the ultimate trunk water system, a fair and equitable manner of revenue generation will be developed using area and connection charges to pay for the trunk water system. We will review the City's existing charge system and make recommendation for improvements. Task 8: Report and Presentation The Bonestroo report will include graphics and figures to clarify items discussed in the report. The information in the report will be organized for ease of access by various audiences. A clear, concise Executive Summary and Recommendations section will assist the City Council and the city staff to review this document. Technical information will generally be placed in an appendix. This work consists of the following subtasks: • Draft Report for Staff Review: For several of the major tasks described above, technical memoranda will be prepared and submitted to Cottage Grove for review. Because the results of one task can affect others, technical memoranda on each task will be prepared as the task is completed. We will attend one review meeting with City staff. A draft report for the entire study, including all applicable maps, figures, and appendices will be compiled and presented to city staff for review. • Final Report: Following review by city staff, a final report will be prepared and 25 copies submitted to Cottage Grove. Cite of Cottage Grove Costs November 10, 2004 Page 5 We propose to complete the Water Supply and Distribution Plan Update for a lump sum of $10,200. This cost is broken down by task in the following table. Task Cost 1. Project Initiation $500 2. Water Use Review $400 3. Well Field Review $200 4. Water Treatment Evaluation $800 5. Hydraulic Modeling $6,500 6. Capital Improvement Plan $400 7. Economic Analysis $400 8. Report $1,400 Total Water Plan Update $10,600 We look forward to discussing this proposal with you. Please call me at (651) 604 -4842 after you have had a chance to review this information. Sincerely, BONESTROO, ROSENE, ANDERLIK & ASSOCIATES, INC. 11!a'l— Mark D. Wallis Cc: Harry Taylor, City of Cottage Grove Les Burshten, City of Cottage Grove Tom Thompson, Bonestroo Bonesti JA Rosene Anderlik & Associates Engineers & Architects April 26, 2005 Ms. Jennifer Levitt City of Cottage Grove Public Works Department 8635 Point Douglas Road Cottage Grove, MN 55016 2335 West Highway 36 ■ St. Paul, MN 55113 Office: 651 -636 -4600 - Fax: 651 -636 -1311 www.bonestroo.com Re: Water Supply and Distribution Plan Update Dear Jennifer: As requested, we have developed a work plan to update the 1995 Water Supply and Distribution Plan. This letter outlines the major issues and provides a scope of work to update the plan. Where appropriate, we have listed tasks that City staff will perform. Major Issues There are three major issues for the Water Supply and Distribution Plan to evaluate: growth, phasing, and financing of proposed improvements. Additionally, State legislation requires all public water systems to prepare a Water Supply Plan. Growth: The basic purpose of the Water Supply and Distribution Plan Update is to provide a guide for orderly expansion of the trunk water system to handle the projected growth of the City. Changes in the development patterns and land use have changed the projected 2020 population and ultimate population from the estimates in the 1995 plan. The East Ravine Community Pre - design Study looked at land use and development phasing for the East Ravine area. We will incorporate that plan into this update and also look at the impact of growth beyond the East Ravine Study Area out to the City limits. Another growth factor relates to the siting of water system facilities such as wells, water storage facilities, and water treatment plants. Often there is considerable opposition to placing water system facilities in certain areas of the City. For example, residents are often opposed to placing a water tower in a residential area. Also, these water facilities take a significant amount of land. As land prices have increased, it becomes more important than ever to be strategic in locating future water system facilities, and include the cost of land acquisition in the financial analysis. Phasing: The East Ravine Community Pre - design Study evaluates phasing of development for the East Ravine. We will incorporate this phasing plan as well as current planning for the remainder of the City to prepare a water system capital improvement plan for the entire City of Cottage Grove. Additionally, we will identify key "triggers" for implementing water system improvements so the City can better plan when to start each facility and can update the CIP based on actual growth. Financing of Proposed Improvements: One fundamental question this study must answer is, "How will the City pay for the proposed improvements ?" The study will update the City's cost recovery system (area • St. Paul, St. Cloud, Rochester, Willmar, MN ■ Milwaukee, WI • Chicago, IL Affirmative Action /Equal Opportunity Employer and Employee Owned City of Cottage Grove Water Supply and Distribution Plan Update April 26, 2005 Page 2 charges, connection charges, and lateral benefit) based on the latest cost estimates for the ultimate water system and the latest estimates for future connections and developable acres. Agency Requirements: Minnesota legislation requires all public water systems serving more than 1,000 people to update their Water Supply Plan (Conservation and Emergency Preparedness Plan) every ten years and submit the plan to the Minnesota Department of Natural Resources (MnDNR) and the Metropolitan Council. This study will fulfill those requirements. Basic Work Plan We have presented an outline of the tasks required to update the 1995 Water Supply and Distribution Plan below. Task 1: Project Initiation and Data Collection We will review data and information collected for the 1995 Water Supply and Distribution Plan and supplement that data with information and data for facilities constructed since the 1995 plan publication. Additionally, we will facilitate and attend one meeting with Cottage Grove staff. This "kick -off meeting" will be used to obtain data from the City, and to get input on any changes, modifications, or improvements they would like to see in the water system, and review the City's 2025 and Ultimate Land Use Plan. Task 2: Water Use Review and Projections We will obtain and review water use data collected since the 1995 plan in order to establish existing water use patterns. Our report will present summaries of water use patterns as required by the Met Council and MnDNR and estimate future water use patterns within the City. We will establish water use at points throughout the City based on the updated land use plan along with average day and maximum day water demands for the years 2025 and the ultimate build out of the City. We will review maximum fire flow requirements based on the Insurance Services Office and City requirements (provided by the Cottage Grove Fire Official). Bonestroo will use GIS to calculate developable acres by land use type for each of the junction nodes created for the computer model and establish design water use patterns for the year 2025 and the ultimate City build -out. Because the result of this task affects the remainder of the study, we will meet with the City to review the projected water demands and fire flow requirements. For this task, we anticipate the City will provide population projections, summarize water use (average and maximum day use for the Grove, Estates, and High Zone), provide water billing summaries (water use by customer type and top 10 users), provide a copy of the latest ISO Report, and provide a representative from the Fire Department at the meeting. Task 3: Well Siting Study As Cottage Grove develops, it must reserve sites for future wells. To complicate the issue, the City has a number of constraints on future well locations such as the 3M Site, nitrate contamination, land use conflicts, and geologic factors. While a well siting study is usually part of the scope of work for a water supply and distribution plan, it is essential that Cottage Grove determine how many wells are required and possible locations of those wells. Building on the results of our 2003 North Well Field Study, we will examine the ultimate demands that will be placed on the Cottage Grove water supply system and calculate the number of well sites required to meet those demands. Based on the number of projected wells, availability of sites, the capacity of the aquifer in the area, and the layout of the water supply system, the study will identify sites that are most suitable. The capacity of the aquifer will also define the well spacing requirements in order to avoid excessive well interference. City of Cottage Grove April 26, 2005 Water Supply and Distribution Plan Update Page 3 The subtasks of the well siting study are, as follows: Subtask 1: Data Collection, Review, and Analysis — We will review data collected from previous aquifer pumping tests, both City wells and surrounding high capacity wells, to better define aquifer transmissivity over a wider area of Cottage Grove. In addition, drawdown and well interference data from Well No. 11 will be collected to better characterize the aquifer in the northern -most portion of the City. Aquifer transmissivity calculations will be used to provide a better understanding of well spacing requirements and overall capacity of the aquifer within a given area. Subtask 2: Well Siting Anal — An analysis of the water supply system layout, along with an analysis of water demand over the City will help pinpoint areas with the greatest need for future wells. Placement of wells will also consider local factors such as bedrock geology, aquifer vulnerability, the proximity of any nearby contamination sites (i.e. the 3M site), and locations of elevated nitrates concentrations. The successful design of the well field must take these factors into account in conjunction with aquifer capacity. Subtask 3: Well field modeling — Computer modeling of well field layout and design will be used to develop predictions of well drawdown and interference over periods of highest pumping demand, when the stress applied to the aquifer is at its greatest. Modeling of different well field scenarios will help to plan future well locations based on the highest predicted pumping efficiency. We will attend one meeting with City Staff to review potential well sites. Subtask 4: Report of findings — We will incorporate the results of the previous three tasks into an appendix to the Water Supply and Distribution Plan, summarizing the findings of the study and presenting a well field layout with the highest probability of success. Task 4: Water Treatment Evaluation We will review the existing well water quality with respect to current and proposed drinking water standards. This evaluation will include both public health concerns and aesthetic issues such as taste, odors, and "red" or "black" water complaints. The City will provide recent water quality tests for every well. We will take the results of the Well Siting Study and evaluate potential sites for future water treatment plants. This analysis will consist of comparing costs and benefits of single, centralized treatment vs. multiple treatment plants. We will also provide cost estimates for the treatment plants recommendations for the amount of land to reserve for treatment plants. Task 5: Hydraulic Modeling We will upgrade the existing hydraulic model of the Cottage Grove Water System to a WaterCAD model. WaterCAD is a powerful analytical tool that operates in a totally integrated AutoCAD and GIS environment. The computer model and results can be viewed with City base maps, land use maps, or integrated into a City GIS system. By simulating operation of the water system, the computer model: • Reveals system problems • Predicts the effects of alternative solutions • Predicts the effects of system expansions We will add pipes constructed since the 1995 Plan to the model and check the calibration of the model to actual system performance. The model will then be used to evaluate the performance of the existing water system and to size future trunk water mains to serve development. Additionally, the model will be used to: • Determine the need for and location of industrial park storage City of Cottage Grove Water Supply and Distribution Plan Update April26, 2005 Page 4 • Locate replacement supply and storage sites originally planned for the drive -In theater site • Determine how to adjust PRV settings in the West Draw area • Determine need for a water tower in the Grove area • Determine size and location for connection between Pinehill Tower and the Grove Area Task 6: Capital Improvement Plan A water utility must have a sound basis for planning the expansion of its water system. This is especially true now, with increasing regulations regarding property acquisition, public notification and construction. A sound Capital Improvement Plan (CIP) will enable Cottage Grove to have the required facilities in place when the need arises. We will prepare the CIP for the trunk water system and break it down in one -year increments through 2010, in five -year increments through 2025, and consider remaining improvements post -2025. Based on the best available projections from the City for population, land use, and water use, it will be linked to benchmark events to allow Cottage Grove to update the CIP easily. For example, wells and water towers will be tied to water use thresholds. Distribution system improvements will be linked to future development or to coincide with street reconstruction projects. Task 7: Economic Analysis The operation of a water utility must have a sound financial basis. The report will present planning -level cost estimates for all of the proposed trunk water system facilities. An estimate of the land required for wells, water towers, and water treatment will be provided so that the cost of each facility can include an estimated cost for land acquisition. These costs will be based on City provided land costs and included in the CIP described above. Based on the overall cost of the ultimate trunk water system, we will review the City's existing fee system and make recommendation for adjustments. Task 8: Report and Presentation The Bonestroo report will include graphics and figures to clarify items discussed in the report. The information in the report will be organized for ease of access by various audiences. A clear, concise Executive Summary and Recommendations section will assist the City Council and the city staff to review this document. An appendix will contain technical information. This work consists of the following subtasks: Subtask 1: Draft Report for Staff Review — For several of the major tasks described above, technical memoranda will be prepared and submitted to Cottage Grove for review. Because the results of one task can affect others, technical memoranda on each task will be prepared as the task is completed. We will attend the following meetings with City staff: Meeting Goals Kick -off Me tin Review scope of project, obtain data Progress Meeting 1 Establish design population projections and ultimate water demands Progress Meeting 2 Review existing system hydraulic analysis and well siting study preliminary results Progress Meeting 3 Review ultimate system analysis Progress Meeting 4 Review draft report, CIP, and economic analysis City of Cottage Grove Water Supply and Distribution Plan Update April 26, 2005 Page 5 A draft report for the entire study, including all applicable maps, figures, and appendices will be compiled and presented to city staff for review (at Progress Meeting 4). Subtask 2: Final Report — Following review by City Staff, we will prepare a final report and submit 25 copies to Cottage Grove. Costs We propose to complete the Water Supply and Distribution Plan Update for a lump sum of $39,775. The following is the estimated project budget by task. Task Cost 1. Project Initiation $ 1,800 2.Water Use Review $ 1,300 3. Well Field Review $ 8,800 4. Water Treatment Evaluation $ 1,800 5. Hydraulic Modeling $ 8,100 6. Capital Improvement Plan $ 1,600 7. Economic Analysis $ 1,500 8. Report $13,875 Reimbursables $ 1,000 Total Water Plan Update $39,775 Additional services not addressed in this scope of work, such as additional meetings, East Ravine review and the NPDES non - degradation modifications, will be billed at the hourly rates previously agreed to in our contract with the City. We look forward to discussing this proposal with you. Please call me at (651) 604 -4911 after you have had a chance to review this information. Sincerely, BONESTROO, ROSENE, ANDERLIK & ASSOCIATES, INC. m Cc: Harry Taylor, City of Cottage Grove Les Burshten, City of Cottage Grove Mark D. Wallis, Project Engineer - Bonestroo TO CkTq 6/ ty c' Bonestroo, Rosene, Anderlik and Associates, Inc. is an Affirmative Actic..., equal Opportunity Employer BonesBones and Employee Owned tr Principals: Otto G. Bonestroo, PE. • Marvin L. Sorvala, P.E. •Glenn R. Cook, P.E. •Robert G. Schunich[. P.E. Rose Jerry A. Bourdon, P.E. • Mark A. Hanson, P.E. 1 �,nderl il< & Senior Consultants: Robert W. Rosene, P.E. •Joseph C. Anderlik. PE. •Richard E. Turner, P.E. •Susan M. Eberlin. C.PA. NDO Associate Principals: Keith A. Gordon, P.E. • Robert R. Pfefferle. P.E. • Richard W Foster, P.E. David O. Loskoca, P.E. Assoc iates Michael T. Rautmann, P.E. • Ted K. Field, P.E. • Kenneth P. Anderson, PE. •Mark R. Rolfs, P.E. • David A. Bonestroo, M.B.A. A La.• Sidney P. Wliliamson, P.E., L.S. • Agnes M. Ring, M.B.A. • Allan Rick Schmidt. P.E. •Thomas W. Peterson, P.E. Engineers & Architects James R A. Mal and, E . •• S ilex Sheldon Johnson • Dale e! P.E. P s A. RE. PE RobertJ! Devery P.E. c Offices: St. Paul. St. Cloud, Rochester and Willmar, MN • Milwaukee, WI • Chicago, IL Websi *_e: www.bonestroo.com June 9, 2003 Ms. Nancy Hanzlik, P.E. City of Cottage Grove 8635 West Point Douglas Road South Cottage Grove, Minnesota 55016 Re: COTTAGE GROVE WELL SITING ANALYSIS Our File 48 -02 -161 Dear Ms. Hanzlik: INTRODUCTION Continued growth of the City of Cottage Grove has led to the e s pec l at amandseln r the general ar municipal wells will need to be added in order to meet water s uppl y north of the existing main well field, nine sites were identified potential could accommodate a population ll of These nine sites, added to the current water supply system, in end presented approximately 60,000- 70,000 people, The final recomm w th the 1995 Supply Figure 2. This layout was planned and evaluated in accordance and Distribution Plan. oned an expansion of the city's existing The City's 995 Water Supply and Distribution plan envisi is well north well field, north of 80 Street into the Pinetree Pond Ed 19 planSThecpurpose of this field layout was presented in the attached Figure 6, copied from the report is to perform a more detailed analysis of the suitability of these sites for future wells. The first step of this analysis was to perform a cursory field site review. Potential well sites were evaluated based on the following factors. ✓ City -owned property ✓ Access to site for well construction, maintenance and operation ✓ Proximity to existing trunk watermains ✓ Cursory field review of site factors relating to well construction Based on these factors, the sites shown in Figure 6 from e for predicted t d l revised drawdown and potential well interference. as disc Figure 1. These potential ussed in the remainder this evaluated „n . /_r_1-f, - -1f,-4600 a Fax: 651 -636 -1311 BACKGROUND quan tit a ti ve ly model future well spacing scenarios, existing aquifer pgtem 2000, showed the data for the City In order to quant y of Cottage Grove was analyzed. The aquifer test data, collected m the data showed a high etween distance- drawdown relationship b at Well 7 Well 8 was pumped. This interference Citi area not other Twin percentage of drawdown interference shis as served in correspond with typical distance- drawdown relatione a n p November 002 and gather more communities, so the decision was made to re -test t q extensive data in order to effectively model Cottage Grove's proposed well field. NOVEMBER 2002 AQUIFER TEST AND ANALYSIS The first aspect of November 2002 aquifer testing was to allow a ll urn ells stly static Cottage condit ons main well field to rest for 24 hours a his allow we the e, a well fi ate measure of total drawdown could acc By knowing the static water level taken along with knowing how much "available" drawdown was at each current well site. ' and static water measurements taken, automatic After the we l l s were allowed to rest for 24 hours data co ll e ction instruments were installed at Wells 6, 7, and 8. during he test co l lect the water levels in the wells and provide continual readings of drams down pumped at a gpm (gallons per minute) fora t otal of 26.5 hours. Well 8 was then pump approximately 1800 the p umping, drawdown was measured by hand at Wells he, surface W e l l 3 could At 23 hours into water in p p to et a water level meter down not be measured, due to an an d 8. the well. Water levels were also being automatically recorded in Wells 6, 7, o f 24 of Well 8, the well was shut off and allowed to recover for a period the pumping and 8 monitored the recovery of Following hours with no other wells running. The instruments in Wells 6, 7, the water levels in the aquifer. DATA ANALYSIS d while collected showed that Well 8 experienced approximately The following t ta bl e s h o ws the The data cr eno d pumping 1800 gpm) at the end of the 26.5 -hour pumpin p amount of drawdown interference observed at other wells in the well field: Well �at W ater Level with Well Name (feet) 8 Pumping (feet) Drawdown Interference from Well 8 ( feet) Well 9 98.93 1 136.29 13.04 Well 4 1 123.25 1 78 84 1 15.09 Wells 6 63.75 1 142.50 16.45 Well 6 1 126.05 1 113.54 4 49.29 e117 6 64.25 7* 8 81* Well 8 9 96.18 1 14.97 approximate Distance From Well 8 (feet 1550 1100 1100 850 950 0 1000 Well 9 93.24 1 * water level fluctuates slightly in a pumping well as the pump surges making a more exact reading difficult ears to be an anomaly, with drawdown The data shows that the drawdown interference at xpa d aquifer. The reason interference at Wells 4, 5 6, and 9 falling within expectect ed ranges for the Jordan ear to be any for elevated drawdown interference at Well 7 would account forhthe a ddi t i ona l drawdown. It is difference in the construction of Well 7 that com posed fi ain sands, possible that a small area of the Jordan aquifer around w ell 7 farther to support it, that locally reducing the transmissivity of the aquifer. conclusion cannot be made. well f test data and distance - drawdown data fr other e om the othe f) w th storage coeffi pro The aquifer ent of estimated transmissivity of 44,000 gpd/ft (gallons p er day pr observed in the Jordan missivity corresponds with the average transmiss 0.0004. This trans ivity and Brietkrietz, A Water Resources Aquifer in the Twin Cities area (Norvitch, R.F., Ross T.G., olis - St. Paul Metropolitan Area, Minnesota, United State Geological Outlook for the M innea P Survey, 1974). transmissivity, a numerical groundwater - model west The pred well model predicted dra wdo w n To ver ify this the pumping test and interference using the values collected during gpm p ap aquifer with a transmissivity of 44,000 the following results from a well pumping gpd/ft and a storage coefficient of 0.0004: Predicted Drawdown Distance From Pumping (feet) Well (feet) 81.2 0 18.5 800 17.4 900 16.5 1000 15.6 1100 suppor the findings from the aquifer test, with only a slightly higher The numerical model supp _ prediction is prediction of drawdown at the obsery ation wells. At 100 9, which displays a 90 ac uuracy of the 1.53 feet greater than the observed drawdown diction is only 0.51 feet greater eater than observed at model. At 1100 feet, the distance - drawdown p re well itself, virtually no Well 5, which displays 96% accuracy in the pr d b measured g difference between the model and observed co FUTURE WELL SPACING PREDICTIONS the next step was to apply those After determining aquifer parameter �? ll on for the future well field. Id. Th The first was findings to develop predictions of questions that needed to be answered to test the feasibility of the proposed based we on static water levels to determine the maximum allowable well drawdown a evations. The second was to determine how much drawdown n d simulate max m can bin interferenc and pump intake el Thi anticipated between the wells when the en occur we ll field g pimp of drought or during emergency withdrawal from the aquifer, w hich may situations. Table 1, attached, summarizes the results described below. Static Water Level In order to compare mode drawdown with well field specific condition current s, urrent future well St atic water level was essential to determine d using av the f o f data: Si tes. Static Water Elevations were evaluate Well construction data, 1960 to 1980. y, 1990' ° Geologic Atlas C -5, Washington Count ° Minnesota Geological Survey uifer Potentionmenc Contours. Hydrogeology Plate, Prairie -du -Chien — Jordan Aq to Present, City Well &Pump Record Plan s, and the ® Static Water Level Measurements 1960 Minnesota County Well Index Data Base• ° Field Measurements of Wells 3 -9 on November 18, 2002. ver the Years) with no ears are on the apparent trend towards declining. However, it app Based on this data, the static water level has been ars that f the data fluctuatioons through the y to per end o c b approximately 30 feet for analysis to allow for fluctuations of the water level. order of 30 feet. The November 18, 2002 measurements is generally are at the u p range. Therefore, the measurements were r im d Static Water Level in Table ee for wells located north and east of the existing well field. is shown as the The static water level elevations increase Jordan Formation tion from the ' wells utilize the Jordan Sandstone aquifer. There is c l ased 15 feetunto the Jordan All of the City's we enerall overlying Prairie -du -Chien formato ld also be ca 15 feet n to the Jordan formation. formation. Proposed future wells well field. generally increases to the east of the existing itan The top elevation of the Jordan Formation g Y The Metropolitan Counc "Water Resources Outlook for the Minneapolis- Sandstone in the Metropolitan Area ", Figure 14, "Structure Contours At the Top of the Jordan n " was used to estimate the top elevation of the Jordan sandstone at future well sites. A 1973, Well Pump Settings his t e, the top of the pump is generally set at a depth in of safety and helps In municipal wells oft yp evel. This allows a small feet submergence beneath the pumping water l g to prevent pump cavitation. Pump assemblies, including the suction pipe or submersible motor are above the bottom l of the well _ b ottom of the pump assembly should no be lower than several eet o level of 50 feet casin .Adding the 30 feet of submergence results in a lowest desirable pumpinb g above the bottom of the casing. Allowable Drawdown I The maximum a ll owa bl e drawdown was estab ished by subtracting the lowest desirable pumping water level from the adjusted static water level. Modeling Methodology and Results was cal model used to verify the aquifer test results the aquifer r est, w with the exception of predicting The numen good distance - drawdown at the observation wells monitored during d T makes h a ammeter ells in C Well 7 which a pp ea rs to be an anomaly in Cottage Grove's well field. This model a tool in predicting well interference close to t future observed in Wells 4, 5 6, 8, and 9. conditions in the Jordan aquifer are m. Wells 4, 5, Wells t 8, s and future Wells 11 -19 were For m the modeling scenarios provided, Well 3 was modeled at a discharge of 8 gp and 6 were modeled at a discharge of 1000 gp r a 24 hour period to reflect These discharges reflect possible use of the for as the City s well field modeled at 1500 gpm• simultaneousl} Q mods of nears full capacity. All wells were modeled X u erieng e in the summer months oz durin p possible peak demand rates the City may p s it is expected that most wells will be drawn down to within 95% of their drought. After 24 hours, " l steady state" pumping level. was compared to the maximum allowable The predicted drawdown, including interference, well field shown in Figure 1, the drawdown established for each well. With the initially proposed drawdowns are exceeded at Wells 4, 6 througe at these wells- 1, Column maximum allowable 8 to 30 f 12). The maximum allowable drawdown was exceeded by removing Of the proposed future wells, Well 12 has the greatest eff Wn° are genertally acceptable (Table 1, Well 12 from the well field model, the p redicted drawdo e casing. As the exce tion of Well 8, located in the center of the well field e exisng well field. The with the p Column 13), predicted pumping water level is only 31 feet above the bottom o t nears completion, the Well No. 8 pump may require special consideration and routine monitoring. ginal Well 12 location as a potential The proposed well field was revised to simply reserve the ori location for Well 19, should actual well field conditions allow for the the fire n l may be usable 2 shows the revised and recommended well field. The location near in the future if' The well field performs better than predicted ® One or more of the existing wells are sealed in the future RFCOMM ENDATIONS 2 is 1. Construction of Wel is 11 through 18 at the locations shown on u should be uffricient to With the additional of Wells 11 through 60,000. the water supply capacity serve a total population in excess o pumping and recovery test 2. As Co ttacre Grove adds wells, it is recommended normal tes 4 pum ping that occurs during well also be conducted at each as part of the new well norm development. This test data can be used to refine the predi occur °f cu elsewhere and nthe determine whether the conditions observed data collection requirements to update the Additionally, this testing will comply wellhead protection delineation for each new well. 3. The pump settings in existing Wells 3 through 6 should be deepened when the pumps are pulled for routine maintenance. The pump settings in Wells 7 through 9 should be sufficient until the City's well field is near completion. It appears that Well No. 8 will require special pump considerations and routine monitoring. 4. Since the numerical modeling is only an approximation of real -world pumping conditions, it is recommended that another round water levels be taken at Cottage Grove's well field the next time the City experiences peak demands on the well field. With all (or most) of the wells running simultaneously, the following data should be recorded from each well: 1. Pumping rate of well. 2. Depth to water at well. 3. Length of time well was pumping at time of water level reading. This data can be compared to static water level data collected during the November 2002 aquifer test and the drawdown at each well can be compared to the predictions of the numerical model. With this real -world data available, the accuracy of the model can be determined, either lending support to the model's predictions or providing data to make revisions to the model. Additionally, this data can be used to determine if the greater drawdown at Well 7 will pose a problem for the City as new wells are added to the well field. We trust this information meets your needs. Please contact us at (651) 636 -4600 if you have any comments or questions regarding this well siting analysis. Sincerely, BONESTROO, ROSENE, ANDERLIK, AND ASSOCIATES, INC. 4 Mark Janovec Hydrogeologist Richard Foster, P.E. Mark Wallis, P.E. cc: Harry Taylor — City of Cottage Grove Les Burshten — City of Cottage Grove Jerry Bourdon — Bonestroo 70th ST Nd, A 2 '�, qi4�: 24 w 21 Y8 No. 19: �� • 24 E„, t. "� � . ..:�. `rte — C N a .. ........ %, .1 .............. . u N o..1 t 0. 1 f2' IT 72 N 0. 2 ST 12' .80th 0 17' 24 Y " UTukt%� a .75 3 OMG TREAT) p w Xb.20: T* �Oos rN No-91 No. .............. . �, ,o-s ��•�� ----------- 24 ........... e<1 1200 E3onestroo FIGURE NO. 6 COTTAGE GROVE, MINNESOTA WATER SUPPLY AND DISTRIBUTION PLAN Rosene Anderlik & Associates Bonestroo T ITERATION Posene WELL LOCATIONS - rlr " Anderlik & FIGURE 1 Associates COTTAGE GROVE, MINNESOTA " Engineers & Architects NORTH WELL FIELD ANALYSIS A 0 n) I Al SE I mv FINAL RECOMMENDED WELL LOCATIONS COTTAGE GROVE, MINNESOTA FIGURE 2 NORTH WELL FIELD ANALYSIS Bonestroo Rosene Anderlik & Associates Engineers & Architects Top of Casing Top Well No. I Capacity I Elev ation (ft.) Elev EXISTING WELLS 5' 92 5 ' 105 5$ 106 5d 106 5 118 59 130 5 � _ 120 3 800 xisting Wells 4 1,000 Entire Wellfield 5 1,000 or 24 hrs (ft.) 6 1,000 856 7 1,500 ggg 8 1,500 888 9 1,500 N/A PROPOSED FUTURE WELLS 11 1,500 101 (18 12 1,500 13 1,500 14 1,500 15 1,500 16 1,500 17 1,500 18 1,500 19 1,500 Predicted 5' 92 5 ' 105 5$ 106 5d 106 5 118 59 130 5 � _ 120 Drawdown, Predicted xisting Wells Drawdown for 3 -9 Running Entire Wellfield continuously Shown in Fig. 1 or 24 hrs (ft.) (ft.) Predicted Drawdown for Entire Wellfield Shown in Fig. 2 (revised Well No. in Parentheses) ggg 5' 92 5 ' 105 5$ 106 5d 106 5 118 59 130 5 � _ 120 125 117 914 143 133 852+ 138 129 920 155 138 856 146 139 ggg 165 154 888 158 147 N/A 55 N/A 5 N/A 5 N/A 5 ' N/A 5 N/A 5 N/A 6 + N/A 6 N/A 6 N/A 95 93 (11) N/A 163 N/A N/A 130 124 (12 N/A 115 111 (13 N/A 142 132 (14 N/A 134 129 (15 N/A 112 108 (16 N/A 116 112 (17 N/A 103 101 (18 Bone -yo Rosert.. Anderiii< & Associates Engineers & Architects April 26, 2005 Ms. Jennifer Levitt City of Cottage Grove Public «Yorks Department 9635 Point Douglas Road Cottage Grove, l\INT 55016 2335 West Highway 36 • St. Paul, MN 55113 Office: 651 - 636-4600 ■ Far.: 651 - 636 w\ Aw,cbonestroc.com Re: Water Supply and Distribution Plan Update Dear Jennifer: As requested, we have developed a work plan to update the 1995 Water Supply and Distribution Plan. This letter outlines the major issues and provides a scope of work to update the plan. 'Where appropriate, we have listed tasks that City staff will perform. Major Issues There are three major issues for the Water Supply and Distribution Plan to evaluate: growth, phasing, and financing of proposed improvements. Additionally, State legislation requires all public water systems to prepare a Water Supply Plan. Growth: The basic purpose of the Water Supply and Distribution Plan Update is to provide a guide for orderly expansion of the trunk water system to handle the projected growth of the City. Changes in the development patterns and land use have changed the projected 2020 population and ultimate population from the estimates in the 1995 plan. The East Ravine Community Pre - design Study looked at land use and development phasing for the East Ravine area. We will incorporate that plan into this update and also look at the impact of growth beyond the East Ravine Study Area out to the City limits. Another growth factor relates to the siting of water system facilities such as wells, water storage facilities, and water treatment plants. Often there is considerable opposition to placing water system facilities in certain areas of the Citr. For example residents are often opposed to placing a water tower in a residential area. Also, these water facilities take a significant amount of land. As land prices have increased, it becomes more important than ever to be strategic in locating future water system facilities, and include the cost of land acquisition in the financial analysis. Phasing: The East Ravine Community Pre- design Study evaluates phasing of development for the East Ravine. We will incorporate this phasing plan as well as current planning for the remainder of the City to prepare a water system capital improvement plan for the entire City of Cottage Grove. Additionally, we will identify key "triggers" for implementing water system improvements so the City can better plan when to start each facility and can update the CIP based on actual growth. Financing of Proposed Improvements: One fundamental question this study must answer is, "How will the City pay for the proposed improvements ?" The study will update the City's cost recovery system (area St. Paul, St. Cloud, Rochester, Willmar, MN . Milwaukel?, WI i Chicago, IL Affirmative Action /Equal Opportunity Employer and Employee Owned City of Cottage G Water Supply and Distribution Plan Update April 26, 2005 Page 2 charges, connection charges, and lateral benefit) based on the latest cost estimates for the ultimate water system and the latest estimates for future connections and developable acres. Agency Requirements: Minnesota legislation requires all public water systems serving more than 1,000 people to update their N> Supply Plan (Conservation and Emergency Preparedness Plan) every ten years and submit the plan to the Minnesota Department of Natural Resources QN1nDNR) and the Metropolitan Council. This study will fulfill those requirements. Basic N8'ork PIan ' Ve have presented an outline of the tasks required to update the 1995 \Vater Supply and Distribution Plan below. Task 1: Project Initiation and Data Collection «'e will revie« data and information collected for the 1995 «-ater Supply and Distribution Plan and supplement that data with information and data for facilities constructed since the 1995 plan publication. Additionally, we will facilitate and attend one meeting with Cottage Grove staff. This "kick -off meeting" will be used to obtain data from the City, and to get input on any changes, modifications, or improvements they would life to see in the water system, and review the City's 2025 and Ultimate Land Use Plan. Task 2: Water Use Review and Projections « will obtain and review water use data collected since the 1995 plan in order to establish existing water use patterns. Our report will present summaries of water use patterns as required by the Met Council and A7nDNTR and estimate future water use patterns within the City. NVe will establish water use at points throughout the City based on the updated land use plan along with average day and maximum day Nvater demands for the years 2025 and the ultimate build out of the City. We will revieNv maximum fire flow requirements based on the Insurance Services Office and City requirements (provided by the Cottage Grove Fire Official). Bonestroo will use GIS to calculate developable acres by land use type for each of the junction nodes created for the computer model and establish design water use patterns for the year 2025 and the ultimate City build -out. Because the result of this task affects the remainder of the study, we will meet with the City to review the projected water demands and fire flow requirements. For this task we anticipate. the City will provide population projections summarize water use (average and maximum day use for the Grove, Estates. and High Zone), provide water billing summaries (water use by customer type and top 10 users), provide a copy of the latest ISO Report, and provide a representative from the Fire Department at the meeting. Task 3: Well Siting Study As Cottage Grove develops, it must reserve sites for future wells. To complicate the issue, the City has a number of constraints on future well locations such as the 3M Site, nitrate contamination, land use conflicts, and geologic factors. 'Xhile a well siring study is usually part of the scope of work for a water supply and distribution plan, it is essential that Cottage Grove determine how many wells are required and possible locations of those wells. Building on the results of our 2003 North Well Field Study, we will examine the ultimate demands that will be placed on the Cottage Grove water supply system and calculate the number of well sites required to meet those demands. Based on the number of projected wells, availability of sites, the capacity of the aquifer in the area, and the layout of the water supply system, the study will identify sites that are most suitable. The capacity of the aquifer will also define the well spacing requirements in order to avoid excessive well interference. City of Cottage, April 26, 2005 Water Supply and Distribution Plan Update Page 3 The subtasks of the well siting study are as follows: Subtask 1: Data Collection. Review. and Analvsis — We will review data collected from previous aquifer pumping tests, both City wells and surrounding high capacity wells, to better define aquifer transmissivity over a wider area of Cottaae Grove. In addition, drawdown and well interference data from «jell No. 11 will be collected to better characterize the aquifer in the northern-most portion of the City. Aquifer transmissivity calculations will be used to provide a better understanding of well spacing requirements and overall capacity of the aquifer within a given area. Subtask 2: Well Siting Analysis — An analysis of the water supply system layout, along with an analysis of water demand over the City will help pinpoint areas with the greatest need for future wells. Placement of wells wIII also consider local factors such as bedrock geology, aquifer vulnerability the proximity of any nearby contamination sites (i.e. the 31\4 site), and locations of elevated nitrates concentrations. The successful design of the well field must take these factors into account in conjunction with aquifer capacity. Subtask 3: Well field modeling — Computer modeling of well field layout and design will be used to develop predictions of well drawdown and interference over periods of highest pumping demand, when the stress applied to the aquifer is at its greatest. Modeling of different well field scenarios will help to plan future well locations based on the highest predicted pumping efficiency. We will attend one meeting with City Staff to review potential well sites. Subtask 4: Report of findings — We will incorporate the results of the previous three tasks into an appendix to the 'Water Supply and Distribution Plan, summarizing the findings of the study and presenting a well field layout with the highest probability of success. Task 4: Water Treatment Evaluation VJe will review the existing well water quality with respect to current and proposed drinking water standards. This evaluation will include both public health concerns and aesthetic issues such as taste, odors, and "red" or "black" water complaints. The City will provide recent water quality tests for every well. We will take the results of the Well Siting Study and evaluate potential sites for future water treatment plants. This analysis will consist of comparing costs and benefits of single, centralized treatment vs. multiple treatment plants. We will also provide cost estimates for the treatment plants recommendations for the amount of land to reserve for treatment plants. Task 5: Hydraulic Modeling We will upgrade the existing hydraulic model of the Cottage Grove Water System to a «JaterCAD model. WaterCAD is a powerful analytical tool that operates in a totally integrated AutoCAD and GIS environment. The computer model and results can be viewed with City base maps, land use maps, or integrated into a City GIS system. By simulating operation of the water system the computer model: • Reveals system problems • Predicts the effects of alternative solutions • Predicts the effects of system expansions 'We «Till add pipes constructed since the 1995 Plan to the model and check the calibration of the model to actual system performance. The model will then be used to evaluate the performance of the existing water system and to size future trunk water mains to serve development. Additionally, the model will be used to: • Determine the need for and location of industrial park storage