Wellhead Protection Plan Unit Well 17

Transcription

1 Wellhead Protection Plan Unit Well 17 City of Madison, Wisconsin Prepared For: Madison Water Utility 119 East Olin Avenue Madison, Wisconsin Prepared by: Madison Water Utility Adam Wiederhoeft, P.E. Engineering Section Joseph Grande Water Quality Manager August 2014

2 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 TABLE OF CONTENTS Page TABLE OF CONTENTS... i LIST OF FIGURES... ii LIST OF TABLES... ii LIST OF APPENDICES... ii LIST OF ACRONYMS... iii REFERENCES... iv Chapter EXECUTIVE SUMMARY... ES INTRODUCTION AND BACKGROUND INTRODUCTION LOCATION AND BACKGROUND UNIT WELL HYDROGEOLOGIC CONDITIONS LAND USE, TOPOGRAPHY, AND DRAINAGE GEOLOGY Precambrian Basement Bedrock Cambrian Bedrock Unlithified Deposits HYDROGEOLOGY Lower Bedrock Aquifer Upper Bedrock Aquifer Sand and Gravel Aquifer Groundwater Flow System WELLHEAD PROTECTION AREA DELINEATION ZONE OF INFLUENCE GROUNDWATER MODEL DEVELOPMENT AND ZOC DELINEATION ZONE OF CONTRIBUTION WELLHEAD PROTECTION AREA POTENTIAL CONTAMINANT SOURCES CONTAMINANT SOURCE INVENTORY UNIT WELL 17 WATER QUALITY AND LAND USES LAND USES AND WELLHEAD PROTECTION PLANNING MANAGEMENT STRATEGIES ALTERNATIVE MANAGEMENT STRATEGIES Category 1 - Existing Programs Category 2 - Land Use Controls Category 3 - Intergovernmental Cooperation Category 4 - Monitoring Category 5 - Public Education and Awareness i August 2014

3 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well WATER CONSERVATION PROGRAM CONTINGENCY PLAN MANAGEMENT PLAN Figure LIST OF FIGURES Follows Page 1-1 Location of Unit Well 17 & Other Water System Facilities Geologic Cross-Section Through Madison Unit Wells 27, 17, 24, and , 50 and 100 Year T.O.T. ZOCs Assuming Projected 2030 Pumping Rate , 50 and 100 Year T.O.T. ZOCs Assuming 50 Percent Capacity Pumping Rate , 50 and 100 Year T.O.T. ZOCs Assuming Full Capacity Pumping Rate , 50 and 100 Year T.O.T. ZOCs Assuming Average Pumping Rate for Maximum Pumpage Year Wellhead Protection Area Contaminant Source Inventory Table LIST OF TABLES Follows Page 3-1 Summary of Extent of ZOCs (Capture Zones) Contaminant Source Inventory Summary Minimum Separation Requirements between Public Wells and Potential Contaminant Sources Summary of Management Strategies Emergency Contact Numbers Appendix LIST OF APPENDICES A Wisconsin Administrative Code, Wellhead Protection Plan B Survey Plat - Unit Well 17 C Unit Well 17 Construction Report and Formation Log D Zoning Map Well 17 E Potentiometric Surface - Lower Bedrock (Mount Simon) Aquifer and Areas of Recharge and Discharge F Potentiometric Surface - Water Table Elevation G Distance-Drawdown Calculation (Zone of Influence) H Ultimate ZOCs for Municipal Wells in Dane County I Prohibited Land Uses in WHPAs, Potential Sources of Groundwater Contamination and Land Uses and Their Relative Risk to Groundwater J Clean Sweep Collection Program K City of Madison Well Abandonment Ordinance - Dane County Ordinance Relating to Private Water Systems L Private Wells and Well Abandonment Information M City of Madison Wellhead Protection Ordinance N Water Conservation Information ii August 2014

4 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 LIST OF ACRONYMS Acronym AST BRRTS CCR CSI DCRPC DNR EPA IOC LUST MGD MMSD MSL PHMDC UST USGS SOC TOT VOC WHPP WHPA WHP WGNHS ZOC ZOI Above Ground Storage Tank Bureau for Remediation and Redevelopment Tracking System Customer Confidence Report Contaminant Source Inventory Dane County Regional Planning Commission Department of Natural Resources Environmental Protection Agency Inorganic Compound Leaking Underground Storage Tank Million Gallons per Day Madison Metropolitan Sewerage District Mean Sea Level Public Health Madison and Dane County Underground Storage Tank United States Geological Survey Synthetic Organic Compound Time of Travel Volatile Organic Compound Well Head Protection Plan Well Head Protection Area Well Head Protection Wisconsin Geological and Natural History Survey Zone of Capture Zone of Influence iii August 2014

5 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 REFERENCES Black & Veatch Corporation, December 2006, Madison Water Utility Water Master Plan, Madison, Wisconsin. Bradbury, K.R., S.K. Swanson, J.T. Krohelski, and A.K. Fritz, 1999, Hydrogeology of Dane County, Wisconsin, WGNHS and USGS Open File Report , Madison, Wisconsin. Bradbury, K.R., November 2001, Personal Communication with Earth Tech regarding estimated aquifer parameters (from Joel Giraud, AECOM). Clayton, L. and J.W. Attig, 1997, Pleistocene Geology of Dane County, Wisconsin, WGNHS Bulletin 95, Madison, Wisconsin. Cline, D.R., 1965, Geology and Ground-Water Resources of Dane County, Wisconsin, USGS Water-Supply Paper 1779-U, Washington, D.C. DCRPC (Dane County Regional Planning Commission), 1999, Dane County Groundwater Protection Plan, (Appendix G of the Dane County Water Quality Plan), Madison, Wisconsin. DCRPC (Dane County Regional Planning Commission), 2004, Modeling and Management Program Reports. Published in association with the Dane County Regional Hydrologic Study, the Wisconsin Geological and Natural History Survey, and the United States Geological Survey, Madison, Wisconsin. Dane County, 2013, Dane County Ordinances, Well Abandonment [online], [Accessed 2 December 2013], Available from internet: < FirstSearch Technology Corporation, June/July 2008, Environmental FirstSearch Report, Unit Well 17, Report No Madison, Wisconsin. Hole, F.D., 1968, Soils of Wisconsin Map. University Extension/WGNHS, 1:710,000, Madison, Wisconsin. Krohelski, J.T., K.R. Bradbury, R.J. Hunt, and S.K. Swanson, 2000, Numerical Simulation of Groundwater Flow in Dane County, Wisconsin, WGNHS Bulletin 98, Madison, Wisconsin. Madison, City of, 2013, Wellhead Protection, Sustainability, and Water Conservation Information, City of Madison [online], Accessed 22 August 2013], Available from internet: < iv August 2014

6 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 Madison Department of Planning & Economic Development, 2013, City of Madison Zoning Districts Map, January 2013, Madison, Wisconsin McDonald, M.G. and A.W. Harbaugh, 1988, A Modular Three-Dimensional Finite Difference Ground-Water Flow Model: U.S. Geological Survey Techniques of Water-Resources Investigations 06-A1, 576 p. Mickelson, D.M, L. Clayton, R.W. Baker, W.M. Mode, and A.F. Schneider, 1988, Pleistocene Stratigraphic Units of Wisconsin, WGNHS Information Circular 62, Madison, Wisconsin. Public Health Madison and Dane County, Website, Clean Sweep [online], [Accessed 2 December 2013], Available from internet: Swanson, S.K., 1996, A Comparison of Two Methods Used to Estimate Groundwater Recharge in Dane County, Wisconsin, M.S. Thesis, University of Wisconsin- Madison. (Section Update done by Joel). USDA, 1978, Soil Survey of Dane County, Wisconsin, Madison, Wisconsin. USEPA, 1993, Wellhead Protection: A Guide for Small Communities, EPA/625/R-93/002, Washington, D.C. USEPA 2006, Office of Environmental Information: 42 USC 300h-7: Part C - Protection of Underground Sources of Drinking Water, State Programs to Establish Wellhead Protection Areas (Federal Law Subsection)[online], [accessed 28 November 2007], Available from World Wide Web: < Wisconsin Administrative Code, January, 2013, Chapter NR 809 Safe Drinking Water, Madison, Wisconsin. Wisconsin Administrative Code, February, 2012, Chapter NR Requirements For the Operation and Design of Community Water Systems, Madison, Wisconsin. Wisconsin Administrative Code, January, 2013, Chapter NR Well Construction and Pump Installation, Madison, Wisconsin. Zheng, C., 1991, PATH3D 3.0 A Ground-water Path and Travel-Time Simulator, S.S. Papadopulos and Associates. v August 2014

7 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 EXECUTIVE SUMMARY This report is a Wellhead Protection Plan for City of Madison Unit Well 17. The primary purposes of this plan are to define the wellhead protection area (WHPA) for Unit Well 17 and establish specific criteria for protection of Unit Well 17 and groundwater resources in the WHPA including management strategies to maintain a high quality water supply, free of contamination. The primary goal of wellhead protection planning is to protect water supply wells from contamination and, thereby, protect people who obtain their water supply from those wells. This plan was prepared for Unit Well 17 to conform to the requirements of the Wisconsin Administrative Code, Chapter NR 811, Section 12(6), for wellhead protection planning. All information in this plan is current through 2011 with some updates made in 2012, 2013 and Unit Well 17 is located at 201 S. Hancock Street on the isthmus in Central Madison. It is 340 feet from the shore of Lake Monona. Construction of Unit Well 17 was completed in The well is 801 feet deep, cased through most of the upper aquifer, and is open to both upper and lower bedrock (sandstone) aquifers. Unit Well 17 has a design capacity of 2,300 gallons per minute (gpm). Land use in the vicinity of Unit Well 17 is mixed commercial, government / institutional, general residential and park/conservancy, and with a significant industrial and utility operations district several hundred feet northeast of Unit Well 17. Zoning around the well is Institutional and Governmental. As part of the Dane County regional hydrologic study, a groundwater flow model was prepared for Dane County (Krohelski et. al., 2000) and used to delineate time related 5-year, 50-year, and 100-year time of travel (TOT) zones of contribution (ZOC) for municipal wells including Unit Well 17. Unit Well 17 is located in the primary pumping center, where a significant cone of depression has developed in the lower bedrock aquifer. The groundwater flow direction toward Unit Well 17 is seemingly radial from all directions (Bradbury, 2009). Figure 3-5 shows the WHPA for Unit Well 17. It includes two zones of protection. Zone A is defined by the 5-year TOT ZOC while Zone B corresponds to a 1,200-foot radius around Unit Well 17. The WHPA will provide a conservative protection zone to account for changes in pumping rates, pumping duration, and interference drawdown from other existing and future wells. An initial contaminant source inventory (CSI) was performed for the Unit Well 17 area during April Additional updates have continued through August Known potential and existing contaminant sources and routes within the Unit Well 17 WHPA include sanitary and storm sewers; spill sites; active and closed aboveground storage tank (AST) sites; active and closed underground storage tank (UST) sites; closed leaking underground (LUST) and aboveground storage tank (LAST) sites; gas stations; dry cleaners; auto repair businesses; paint and chemical storage and use; road salt application; and probable use of pesticides, herbicides and nutrients on residential and commercial lawns and gardens. ES-1 August 2014

8 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 Programs and activities to be used by the City of Madison and others for WHPA management around Unit Well 17 are grouped into five principal categories: 1. Existing Programs a. Clean Sweep Collection Program b. On-site waste disposal system maintenance c. Well abandonment d. Land application of sludge and septage e. Spill notification and awareness of remedial investigation and cleanup 2. Land Use Controls a. Existing zoning/wellhead protection zoning overlay and ordinance 3. Intergovernmental Cooperation a. Land use planning and site plan review 4. Monitoring a. Contaminant Source Inventory maintenance b. Water quality monitoring 5. Public Education and Awareness a. Availability of Wellhead Protection Plan b. Public information meetings c. News and social media releases d. Materials distributed to residents in the Wellhead Protection Area e. Land use and contamination source awareness f. School programs Some of these programs and activities are currently being performed, while others are new and will be implemented immediately to help protect Unit Well 17. The Madison Water Utility has an existing water conservation program and encourages water conservation. The Utility has formulated a contingency plan for providing water in the event that Unit Well 17, or one or more of the City s other water supply wells become contaminated or removed from service. Well 17 is part of the city s main pressure zone (Zone 6W); numerous other wells in the main pressure zone can serve this area in the event of a Well 17 failure. The City of Madison also has a Wellhead Protection ordinance and a zoning overlay district. The WHP ordinance helps ensure that new potential contaminant sources are not located in the Unit Well 17 Wellhead Protection Area. ES-2 August 2014

9 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well INTRODUCTION AND BACKGROUND 1.1 INTRODUCTION This report is a Wellhead Protection Plan (WHPP) for City of Madison Unit Well 17. The primary purposes of this WHPP are to define the Wellhead Protection Area (WHPA) for Unit Well 17 and establish specific criteria for protection of Unit Well 17 and groundwater resources in the WHPA, including management strategies to maintain a high quality water supply, free of contamination. The primary goal of wellhead protection (WHP) planning is to protect water supply wells from contamination and, thereby, protect people who obtain their drinking water from those wells. This WHPP was prepared for Unit Well 17 to conform to the requirements of Wisconsin Administrative Code, Chapter NR (6), for WHP planning. The relevant section of the code is found in Appendix A. The project scope includes the following: 1. Research available information regarding the geology and hydrogeology of the well site and aquifer parameters. 2. Research well construction and planned operation of Unit Well Coordinate with Wisconsin Geological and Natural History Survey (WGNHS) for previously delineated 5-year Time of Travel (TOT) capture zones for Unit Well Perform a Contaminant Source Inventory (CSI) to identify and characterize existing and potential contamination sources within a ½-mile radius and within the recharge area equivalent to the 100-year TOT capture zone for Unit Well Define the WHPA for Unit Well Develop management strategies for Wellhead Protection Planning. 1.2 LOCATION AND BACKGROUND Unit Well 17 is located at 201 S. Hancock Street in the central part of the isthmus in the City of Madison, Wisconsin. The well site is located about 340 feet north of the shore of Lake Monona. The site is in the NW ¼, SE ¼, of the SW ¼, of Section 13, Township 7 North, Range 9 East, Dane County, Wisconsin. Figure 1-1 shows the location of Unit Well 17 and other City of Madison Water Utility system facilities. Property land records for Unit Well 17 are included in Appendix B. The well property was platted with the original 1839 plat of Madison. Construction of Unit Well 17 was completed in June The City water system serves approximately 235,000 people and consists of 22 active wells, 29 booster pumping facilities, 25 ground storage reservoirs, 5 elevated water storage tanks, and approximately 840 miles of water transmission and distribution mains. 1-1 August 2014

10 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 Because of the varying topography in the Madison area, the water system is divided into 10 separate pressure zones. Unit Well 17 is located in the Main Pressure Zone (6W), about 3,800 feet south of Unit Well 24 and about 8,400 feet east of Unit Well 27 see Figure UNIT WELL 17 Unit Well 17 was constructed to a depth of 801 feet. The well is cased with 30 - inch outside diameter (OD) steel casing grouted to a depth of 145 feet below ground surface. A grouted 24 - inch OD steel casing continues to a depth of 200 feet below ground surface. A 23 - inch diameter open borehole extends from a depth of 200 feet to the bottom of the well. Sandstone bedrock was encountered at 135 feet. Significant shale beds were encountered over the intervals of 220 to 240 feet and 760 to 797 feet. Granite was encountered at a depth of 797 feet. Unit Well 17 was test pumped at a rate of 3,000 gallons per minute (gpm) and had a specific capacity of 25.4 gpm per foot of drawdown (gpm/ft). At the time of the original test pumping, the static water level in Unit Well 17 was 55 feet below ground surface. The current static water level is 51 feet below ground surface. A construction report and formation log prepared by the Wisconsin Geological and Natural History Survey (WGNHS) is included in Appendix C. The test well construction report is also included in the appendix. Unit Well 17 has a pumping capacity of 2,300 gallons per minute (gpm). It is used as a seasonal well that typically operates from May to October. The well primarily serves the Downtown and Capital areas between Park Street and Blair Street. Annual pumpage for Unit Well 17 is summarized below: Well 17 Pumpage Year Water Pumped (million gallons) Start Date End Date June 5 September June 11 September June 7 December June 20 December July 20* October 15 *Also operated throughout January 1-2 August 2014

11 UNIT WELL 17 DECEMBER, 2013

12 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well HYDROGEOLOGIC CONDITIONS 2.1 LAND USE, TOPOGRAPHY, AND DRAINAGE Unit Well 17 is located in Central Madison on the isthmus between Lake Mendota and Lake Monona. It is located in a primarily commercial area with nearby institutional and governmental properties and with a significant industrial and utility operations district several hundred feet northeast of the well. Current zoning in the vicinity of Unit Well 17 is institutional and/or governmental. A portion of the City of Madison zoning map for the Unit Well 17 area is included in Appendix D. Unit Well 17 is located in a gently sloping area very near the shoreline of Lake Monona. Near surface deposits are lake sediment deposits. The ground surface elevation at Unit Well 17 is about 849 feet above mean sea level (MSL). Surface elevations within a ½- mile radius of Unit Well 17 range from 917 feet above MSL at the State Capitol, which is located about ¼-mile northwest of Unit Well 17 to 845 feet above MSL at Lake Monona. Drainage at Unit Well 17 is to the southeast toward Lake Monona. 2.2 GEOLOGY The area surrounding Unit Well 17 was glaciated by the Green Bay lobe during the Wisconsin Stage. The rocks and unlithified deposits in the area range from Precambrian basement rocks to recent soils. The bedrock from oldest to youngest includes Precambrian granite and Cambrian age bedrock consisting of sandstone, siltstone, shale and dolomite. A geological cross section through Unit Wells 3, 17, 24, and 27 is illustrated on Figure 2-1. Formation logs for strata encountered at Unit Well 17 are included in Appendix C. The stratigraphic sequence encountered in the wells is briefly described in the following sections Precambrian Basement Bedrock Precambrian bedrock was encountered in Unit Well 17 at a depth of 797 feet below ground surface. The Precambrian bedrock encountered in Unit Well 17 is felsite (Wisconsin Geological and Natural History Survey (WGNHS) Well Log DN-935) Cambrian Bedrock Cambrian age rocks encountered in Unit Well 17 include, in ascending order: Mount Simon Formation, Eau Claire Formation and Wonewoc Formation. Cambrian age rocks are relatively flat, lying in the Madison area in the east-west direction and dipping slightly to the south. The northeast - southwest trending crosssection shows relatively flat lying bedrock strata. The thickness of deep rock units is 2-1 August 2014

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14 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 relatively consistent in the Madison area, although there are textural and compositional changes, laterally. The occurrence and thickness of the Wonewoc Formation varies, because it is the upper erosional surface. Strata above the Wonewoc Formation at Unit Well 17 consists of unlithified deposits, as illustrated on Figure 2-1. Pale greenish-gray shale about 15 feet thick is laterally extensive in the Eau Claire Formation Unlithified Deposits Bedrock is mantled by unlithified lacustrine and glacial deposits. Clayton and Attig (1997) classify the local near-surface unlithified deposits in the immediate vicinity of Unit Well 17 as part of the Horicon Member of the Holy Hill Formation, deposited during the Wisconsin Glaciation. Clayton and Attig (1997) report that the near-surface formation is mostly uncollapsed offshore lake sediment consisting of plane-bedded and crossbedded sand; plane-bedded silt and clay and near-shore gravel. The topography is relatively flat, but some of the formation was deposited on stagnant ice resulting in slightly hummocky topography. At Unit Well 17, the formation from the top of the sandstone bedrock (encountered at a depth of 135 feet below ground surface (bgs)) is described as gray and orange sand and gravel (105 to 135 feet bgs), gray mottled clay (100 to 105 feet bgs), pale yellow sand ( feet bgs), yellow and brown clay (60 to 95 feet bgs), grayish orange silt and clay (25 to 60 feet bgs), grayish-orange sand and gravel (10 to 25 feet bgs) and dark gray sand (0 to 10 feet bgs). Soils in the immediate vicinity of Unit Well 17 are classified as the Colwood silt loam, Dodge silt loam (2 to 6 percent slopes), and McHenry silt loam (6 to 12 percent slopes) (USDA 1978). These soils have permeabilities ranging from 0.63 to 2 inches per hour. The Colwood silt loam and McHenry silt loam have fair contaminant attenuation potential. The Dodge silt loam has good contaminant attenuation potential. The Dane County Regional Planning Commission (DCRPC) assigned a groundwater contamination risk classification of moderate from surface activities, and moderate to high from subsurface activities in the Unit Well 17 area on the basis of several factors, including soil properties (DCRPC, 1999). 2.3 HYDROGEOLOGY In the study area, groundwater occurs within the lower bedrock aquifer, the upper bedrock aquifer and the unlithified (i.e. sand and gravel) aquifer. The upper bedrock aquifer and sand and gravel aquifer are often used for private domestic supplies in rural areas. Municipal and most industrial wells are constructed into the lower bedrock aquifer. The following is a brief discussion about the aquifers. 2-2 August 2014

15 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well Lower Bedrock Aquifer The lower bedrock aquifer occurs in the Mount Simon Formation and lower part of the Eau Claire Formation. The Precambrian bedrock is the base of the lower bedrock aquifer and the shale layer in the Eau Claire Formation is the upper confining unit. The shale layer in the Eau Claire Formation occurs at depths of between 225 feet and 240 feet below ground surface. Water occurs within horizontal and vertical fractures, along bedding planes, and between sand grains in the aquifer. The saturated thickness of the lower bedrock aquifer is 557 feet thick in Unit Well 17. The horizontal hydraulic conductivity of the lower bedrock aquifer is estimated to be 10 feet per day (ft/day) and the vertical hydraulic conductivity is estimated to be 1 ft/day (Krohelski et. al., 2000). Unit Well 17 is cased to a depth of 200 feet, which is 25 feet above the Eau Claire shale confining layer. Unit Well 17 is open and rapidly hydraulically connected to both the lower and upper bedrock aquifers. Water levels measured in Unit Well 17 are representative of the composite upper and lower bedrock aquifers. The static water level, measured at Unit Well 17 in early 2009 was 51 feet below ground surface (798 feet above MSL). Figure 4 in Appendix E shows the simulated year 2000 potentiometric surface in the lower bedrock aquifer at the Unit Well 17 site is at about 840 feet MSL at Unit Well 17. The groundwater flow direction in the deep bedrock aquifer toward Unit Well 17 is radially from all directions (Bradbury, 2009). The storativity of the lower bedrock aquifer is estimated to be about , and the porosity is estimated to be about 30 percent (Bradbury, 2001). The porosity of the Eau Claire Formation is estimated to be 5 percent (Bradbury, 2001) Upper Bedrock Aquifer The upper bedrock aquifer occurs in the upper part of the Eau Claire Formation above the shale and within the Wonewoc Formation. Water occurs within fractures, along bedding planes, and between sand grains in the sandstone. At Unit Well 17, the thickness of the bedrock formation above the shale confining layer is 90 feet. The saturated thickness of the upper bedrock aquifer is 90 feet, and the total combined saturated thickness of the upper bedrock aquifer and the unlithified aquifer (i.e. unlithified sand and gravel aquifer) at the time of construction was 170 feet. Figure 3 (DCRPC, 2004) in Appendix F shows the simulated year 2000 potentiometric surface in the upper bedrock aquifer and unlithified aquifer at Unit Well 17 at less than 860 feet above MSL. The horizontal hydraulic conductivity of the upper bedrock aquifer is estimated to vary between 0.5 and 7.0 ft/day, while the vertical hydraulic conductivity is estimated to vary between 0.15 and 7.0 ft/day (Krohelski et. al., 2000). The porosity of the formations is estimated at 5 percent (Bradbury, 2001). 2-3 August 2014

16 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well Unlithified (Sand and Gravel) Aquifer The unlithified aquifer occurs in the near surface lacustrine and glacial deposits (sand and gravel), which are about 135 feet deep at Unit Well 17. As noted, groundwater at Unit Well 17 was encountered at a depth of 55 feet during well construction and it was measured at a depth of 51 feet in early For groundwater modeling purposes, Krohelski et al., 2000, assumed a hydraulic conductivity of 7 ft/day and a porosity of 20 percent for the sand and gravel aquifer Groundwater Flow System Average annual precipitation in the City of Madison area is about 30 to 30.5 inches per year (Cline, 1965; Cotter et al., 1969). Cline (1965) estimated that the amount of recharge to the groundwater reservoir in the Upper Yahara River basin was approximately 6 inches per year (in/yr). Swanson (1996) estimated that the recharge rate in Dane County ranges from 0.3 to 6.7 in/yr and has an average value of 2.6 in/yr. Precipitation infiltrates through the near-surface sediment and recharges the unlithified and shallow bedrock aquifers. Figure E-2 in Appendix E shows the location of Unit Well 17 and areas of recharge to and discharge from the lower (Mount Simon formation) bedrock aquifer (Bradbury et. al, 1999; DCRPC 1999). Unit Well 17 is located in a recharge area. Discharge from the lower bedrock aquifer is primarily at pumping wells such as Unit Well 17. Discharge from the unlithified and shallow bedrock aquifer is also at Unit Well 17 and at surface waters (lakes, streams and wetlands). 2-4 August 2014

17 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well WELLHEAD PROTECTION AREA DELINEATION The following sections describe the methodologies used to define both the Zone of Influence (ZOI) and Zones of Contribution (ZOC) for Unit Well ZONE OF INFLUENCE The Zone of Influence for Unit Well 17 was estimated in accordance with Wisconsin Department of Natural Resources (DNR) requirements 30 days of continuous pumping at the rated pump capacity with no aquifer recharge assumed. The calculated ZOI, to a radius where there is one foot of drawdown, for Unit Well 17 is miles. The ZOI was determined using the Theis equation. The calculated ZOI to a radius of zero drawdown is 23.7 miles. These estimated ZOI are believed to be conservatively large because the Theis equation does not incorporate aquifer recharge or consider effects of potential hydraulic boundaries. For the calculation, it was assumed that the majority of the open borehole, which is open to both the upper and lower bedrock aquifers, supplies water to Unit Well 17. Distance drawdown calculations are provided in Appendix G. 3.2 GROUNDWATER MODEL DEVELOPMENT AND ZONE OF CONTRIBUTION DELINEATION As part of the Dane County regional hydrologic study, a groundwater flow model was prepared for Dane County. It was used to delineate time-related Zones of Contribution for municipal wells including Unit Well 17 (Krohelski et. al., 2000). The regional hydrologic study was conducted cooperatively by the Wisconsin Geological and Natural History Survey (WGNHS), DCRPC, and the United States Geological Survey (USGS). The USGS modular groundwater modeling code, MODFLOW (McDonald & Harbaugh, 1988), was used to simulate groundwater flow. After the calibrated groundwater model was prepared, PATH3D modeling software (Zheng, 1991) was used to determine time related ZOCs. The ZOCs documented in this report for Unit Well 17 were modeled on 03/18/2008 by the WGNHS, University of Wisconsin Extension, in. The model domain covers an area of 50 miles by 60 miles and is divided into 144,000 nodes. Each node has regular spacing of 1,312.4 feet (400 meters) on a side. The grid has 200 rows and 240 columns (Krohelski et. al., 2000). In 2002, the original groundwater flow model was converted from a three layer model to a four layer model. The sand and gravel aquifer is Layer 1; the upper bedrock aquifer Layer 2; the Eau Claire Formation Layer 3; and the lower bedrock aquifer is Layer 4. The model was then recalibrated and various boundary conditions were modified (DCRPC, 2001). Other aquifer parameters input into the model were as previously described in Chapter 2 and Krohelski et. al. (2000). Four groundwater flow simulations were performed by the WGNHS for Madison Water Utility using the calibrated model. They included different pumping rates for existing and known future municipal supply wells in Dane County (Bradbury, 2008). Simulation August 2014

18 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 was performed using the projected pumping rates from municipal wells for the year 2030, when City of Madison pumping is projected to total 44 million gallons per day (MGD). The 2030 pumping rate for Simulation 1 at Unit Well 17 was projected at 1.29 MGD, which is equivalent to continuously pumping at a rate of 896 gallons per minute (gpm). Simulation No. 2 was performed using the maximum sustained pumping rate or one half design capacity (Bradbury, 1998). The maximum sustained pumping rate (one half design capacity) for Unit Well 17 is 1.66 MGD or continuous pumping at a rate of 1,150 gpm. Simulation No. 3 was performed using full design capacity, which is 3.31 MGD for Unit Well 17. This rate is equivalent to pumping continuously at 2,300 gpm. Simulation No. 4 was performed using the average pumping rate for Unit Well 17 for the maximum year (2001). In 2001, Unit Well 17 pumped 2.19 MGD on average, which is equivalent to pumping continuously at a rate of 1471 gpm. Modeling software PATH3D (Zheng, 1991) was used to determine the time-related ZOCs for Unit Well 17. Particles were input to the model around Unit Well 17 and then tracked backward from the well to points where they entered the groundwater flow system. 3.3 ZONE OF CONTRIBUTION FOR UNIT WELL 17 The area that recharges or contributes water to Unit Well 17 is defined as the ZOC. The aerial extent of the ZOC, or capture zone, depends on the pumping rate and duration, amount of vertical and horizontal groundwater recharge, aquifer characteristics, and other stresses on the groundwater such as other pumping wells. It is beneficial to know the extent of the well capture zone because contaminants introduced within the ZOC could reach Unit Well 17. Figure 3-1 shows the 5-year, 50-year and 100-year TOT ZOCs for Unit Well 17 based on the projected year 2030 pumping rate (Simulation 1). Figure 3-2 illustrates time-related ZOCs based on the one-half design capacity pumping rate (Simulation 2) while Figure 3-3 shows the ZOCs based on full design capacity pumping rate (Simulation 3). Finally, Figure 3-4 shows the ZOCs based on the average pumping rate for Unit Well 17 during the maximum pumping year, which was 2001, (Simulation 4). Appendix H shows ultimate regional ZOCs for Unit Well 17 and the other wells in Dane County. Because of its location in the central isthmus, all areas within the Unit Well 17 ZOCs can be considered upgradient of Unit Well 17 (Bradbury, 2009). As shown in Figures 3-1 through 3-4, the time-related capture zones under all pumping scenarios extend outward radially from Unit Well 17, with a slight favoring of a general hydraulic gradient flowing from the northwest. Groundwater flow path lines extend about one mile upgradient from Unit Well 17 to areas to the northwest and southeast of Unit Well 17, beneath Lake Mendota and Lake Monona, respectively. 3-2 August 2014

19 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well WELLHEAD PROTECTION AREA The Wisconsin Administrative Code (Chapter NR (6)(d)) requires that WHPAs for municipal water supply wells encompass, at a minimum, that portion of the recharge area equivalent to a 5-year TOT to the well. Any of the four simulations described above could be used to model the 5-year TOT ZOC for Unit Well 17. It is possible that Unit Well 17 could be pumped at maximum capacity without interruption. Therefore, Simulation 3 provides a realistic, but very conservative, model of the capture zones for Unit Well 17. This model simulation was used to generate the long-term capture zones and to define the WHPA for Unit Well 17. The 5-year TOT ZOC for Unit Well 17 extends radially outward to approximately 990 feet from the well while the 100-year TOT ZOC extends to about 4,750 feet. Protecting the entire 100-year TOT ZOC from Unit Well 17 to the upgradient boundary at the same level of protection as the area within the 5-year TOT ZOC is likely too severe. Figure 3-5 shows the two zones of protection for Unit Well 17. Zone A is the area around Unit Well 17 that is defined by the 5-year TOT ZOC based on Simulation 3 (full design capacity pumping rate). Zone B encompasses a 1200-foot radius around Unit Well 17. This radius was selected because Wisconsin Administrative Code Chapter NR (4) requires a 1,200-foot separation distance between a municipal water supply well and certain potential contamination sources. The 5-year TOT ZOC is entirely contained within the 1200-foot radius (Zone B). The WHPA will provide a conservative protection zone to account for changes in pumping rates, pumping duration, and interference drawdown from other existing and future wells. The WHPA is located entirely within the City of Madison. 3-3 August 2014

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25 TABLE 3-1 SUMMARY OF EXTENT OF ZOCs (CAPTURE ZONE) WELLHEAD PROTECTION UNIT WELL 17 MADISON, WISCONSIN Item Simulated Pumping Rate (MGD) / (GPM) Simulation No. 1 (Projected 2030 Pumping Rates) 1.24 MGD 859 GPM Simulation No. 2 (One-Half Design Capacity Pumping Rates) 1.66 MGD 1,150 GPM Simulation No. 3 (Continuous Pumping at Full Capacity) 3.31 MGD 2,300 GPM Simulation No. 4 (Average Pumping Rate During Maximum Pumpage Year) 2.12 MGD 1,471 GPM Upgradient Extent of ZOC (feet) 5-Year TOT Year TOT 1,980 2,640 3,630 2, Year TOT 3,300 3,630 4,752 4,224 Notes: MGD = Million Gallons per Day ZOC = Zone of Contribution TOT = Time of Travel

26 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well CONTAMINANT SOURCE INVENTORY 4.0 POTENTIAL CONTAMINANT SOURCES A contaminant source inventory (CSI) was initially performed for the Unit Well 17 study area during April 2008 and additional CSI data from 2009 and 2010 are included in this report. Further updates occurred in April and August 2014 to reflect changes to environmental clean-ups, including LUST sites, and re-development activity. The CSI consisted of a government records and database search to identify potential, existing and former contaminant sources around Unit Well 17. A reconnaissance survey of a portion of the area within a ½-mile radius, including general land use observations and reconnaissance, was conducted in December Figure 4-1 shows the location of potential, existing and former contaminant sources in the recharge area equivalent to the 100-year TOT ZOC for Unit Well 17. Also shown are Zone A (5-year TOT ZOC) and Zone B (1,200-ft radius) boundaries. Table 4-1 summarizes the potential contaminant sources that were reported and/or observed to be within the 100-year TOT ZOC. Over 200 potential, existing, or former contaminant source sites were identified in the modeled Unit Well year capture zone. As detailed in Table 4-1, many potential contaminant sites appeared in multiple databases. The database searches identified numerous types of potential, existing and former contaminant sites including: Resource Conservation and Recovery Act of 1967 (RCRA) small quantity generator (SQG) sites [13]; RCRA - conditionally exempt small quantity generator (CESQG) sites [16]; RCRA Non-generator sites - facilities that transport, store, treat and/or dispose of hazardous waste, but do not currently generate hazardous waste [31]; Emergency Response Notification System (ERNS) reported release sites [2]; Toxic Chemical Release Inventory System (TRIS) sites - document chemical releases to the air, water and land in reportable quantities under SARA Title III [2]; FTTS sites (pesticide enforcement actions and compliance activities) that identify sites regulated under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) and the Toxic Substances Control Act (TSCA) [4]; Polychlorinated biphenyls (PCB) Activity Database sites (PADS) [3]; Material Licensing Tracking System (MLTS) sites that possess or use radioactive materials and are subject to National Regulatory Commission (NRC) licensing requirements [5]; Facility Index System (FINDS) database sites [101]; Bureau for Remediation and Redevelopment Tracking System (BRRTS), documenting investigation and cleanup of potential and confirmed soil and groundwater sites [28]; Wisconsin Emergency Repair Program (ERP) sites [17]; 4-1 August 2014

27 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 Leaking Underground Storage Tank (LUST) sites [82]; Underground Storage Tank (UST) sites [139]; Leaking Aboveground Storage Tank (LAST) sites [5]; Aboveground Storage Tank (AST) sites [52]; SPILL sites, which are identified as sites that have had a discharge of some type of hazardous substance that may adversely impact or threaten to adversely impact public health, welfare or the environment [54] Potential, existing and former contaminant sources and routes within the capture zone for Unit Well 17 include sanitary and storm sewers; chemical spill sites; active and closed storage tank [AST, LAST, UST, and LUST] sites; gas stations; power plants (i.e. Madison Gas and Electric and Capitol Heat & Power plants); hazardous waste handling facilities; dry cleaners; auto repair businesses; a carwash; paint and chemical storage and handling facilities; road salt application; and probable use of pesticides, herbicides and nutrients on commercial and residential lawns and gardens. Identified potential contaminant sites within 1,200 feet of Unit Well 17 include several closed or removed UST sites; active UST sites; the two active power plants as noted above, which are both LUST sites; several additional LUST sites; active AST sites; a dry cleaner and various historic spill sites. Water wells are potential pathways to groundwater. A poorly constructed or damaged well may allow contaminants to enter groundwater or to move from one aquifer into another. Wisconsin DNR records identify a high-capacity well at the Madison Gas & Electric Blount Street location, 717 E. Main Street. The well, constructed in 2000, is located approximately 0.25 miles northeast of Unit Well 17 and within the 50 year TOT. This well has a grouted casing to a depth of 200 feet and is assumed to have been constructed according to the requirements of Wisconsin Administrative Code, NR 812. There are no private sewage disposal systems or sludge or septage spreading areas in the vicinity of Unit Well 17. All businesses and residents are served by the City of Madison municipal sewer system and connected to Madison Metropolitan Sewerage District (MMSD). There are no known cemeteries or golf courses in the vicinity of Unit Well 17. The required separation distances between Unit Well 17 and potential contaminant sources identified in Wisconsin Administrative Code NR are summarized in Table 4-2. The minimum setback distances are currently being met with the exceptions of existing sanitary and storm sewer lines and sites with residual contamination exceeding Chapter NR 140 Enforcement Standards as recorded on the Wisconsin DNR GIS Registry. 4.2 UNIT WELL 17 WATER QUALITY AND LAND USES The upper bedrock aquifer is more vulnerable to near-surface contaminant sources than the lower bedrock aquifer. Because Unit Well 17 is cased only in the upper bedrock aquifer, and not through the Eau Claire shale confining layer, it is open to groundwater flows from both the upper and lower bedrock aquifers. 4-2 August 2014

28 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 Raw groundwater extracted from Unit Well 17 is tested quarterly while chlorinated water is tested weekly for coliform bacteria. These bacteria function as indicators to evaluate source water quality and the effectiveness of chlorination and to confirm drinking water safety. None of the samples tested positive for the presence of coliform bacteria. Based on annual water samples collected from Unit Well 17 during the period of 2009 through 2013, water pumped from Unit Well 17 has high hardness [394 mg/l] and it contains iron [0.09 mg/l], manganese [35 µg/l], and sulfate [57mg/L]. Nutrient loading and the impact of road salt application is not apparent at Unit Well 17. Nitrate measurements are consistently below detection [<0.12 mg/l] while sodium and chloride levels appear stable at 20 mg/l and between mg/l, respectively. Water from Unit Well 17 was tested in 2009 for radium, uranium, and gross measures of radiation. Combined radium ( ) measured 1.5 picocuries per liter (pci/l) while uranium was detected but tested below the limit of quantification [LOQ]. The limit for radium in drinking water is 5 pci/l. Samples are analyzed annually for volatile organic compounds (VOC), man-made contaminants including chemical solvents and cleaners derived from petroleum products, which may be present in groundwater. For the period 2009 through 2013, a single VOC [1,2-dichloroethane] was last detected at Unit Well 17 in Except for disinfection by-products, no other VOCs have been detected at Unit Well 17 over the last five years. Synthetic organic compounds include herbicides, pesticides, and other chemicals that come from agriculture, urban storm water runoff, or industrial activities. Regular testing has not detected the presence of nearly forty SOCs. Additional water quality data can be found in Table LAND USES AND WELLHEAD PROTECTION PLANNING Many of the land uses in the vicinity of Unit Well 17 are not compatible with Wellhead Protection Planning, including fuel storage tanks (USTs and ASTs), vehicle maintenance and repair shops, truck staging and parking areas, hazardous waste handling facilities, chemical storage and use, paint storage and use, and dry cleaning. However, these land use activities pre-date Unit Well 17, water utility planning activities, or the more stringent wellhead protection regulations including the required minimum setback distances from a municipally-owned community water supply well. It is not desirable to have commercial, manufacturing, or industrial districts located in WHPAs. Land use activities listed in Table I-1 (Appendix I) should be prohibited in WHPAs. For land uses that currently exist within Zones A or B and do not meet the minimum setback distance requirements (Table 4-2), owners should be allowed to upgrade the 4-3 August 2014

29 City of Madison, Wisconsin Wellhead Protection Plan, Unit Well 17 facilities to enhance groundwater protection. New uses that do not meet the requirements outlined in Table 4-2 should not be allowed in the WHPA. Tables 4-4 and 4-5 in Appendix I summarize several potential sources of groundwater contamination and land uses and their relative risk to groundwater, respectively. These activities should be restricted or eliminated from wellhead protection districts. 4-4 August 2014

30 Madison Water Utility TABLE 4-1 CONTAMINANT SOURCE INVENTORY SUMMARY WELLHEAD PROTECTION UNIT WELL 17 MADISON, WI August 2014 Map Site ID No. FirstSearch Map ID No. Owner/Location Database or Reference Source Existing, Potential, or Former Contaminant Sources Reported Status Approximate Distance to Unit Well 17 Location Within Capture Zone Estimated Threat to Well Madison Water Utility Unit Well S. Hancock St. TIER 2 S Active Municipal Well with chlorine gas on site. Active Municipal Well At Site Zone A Low E. Wilson St. at Lake Monona SPILLS S Historic Spill; diesel fuel spilled into storm sewer and into Lake Monona. Historic Spill 319 ft. ENE Zone A Low Parking Lot 514 E. Wilson St. SPILLS S Historic Spill; hose broke on truck; petroleum contamination; May Historic Spill 384 ft. NE Zone A Low Essen Haus 134 S. Blair St. SPILLS S LUST U BRRTS UST CRS AUL Historic Spill; Closed LUST; Petroleum - contaminated soil and groundwater; September 1998; Conditional Closure with GIS Groundwater Registry for groundwater and soil contamination. Closed/Removed USTs: 1,000-gal waste/used motor oil; (2) 1,111-gal unknown, August and November LUST; Historic Spill; GIS Groundwater Registry Active Restaurant/Hotel 508 ft. N Zone A Moderate WI Dept of Administration 149 E. Wilson St FINDS RCRA-NonGen WID LUST S UST U Closed LUST: May 1992 Closed/Removed UST: 450-gal fuel oil; for government fleet vehicles; October Closed LUST; Closed/Removed UST 557 ft. SW Zone A Low McShane Corp Property 137 E. Wilson St. AST A BROWNFIELDS S BRRTS Active AST: 450-gal diesel; back-up for generator. Active Diesel AST 638 ft SW Zone A Low S. Blair St. & Railroad St. SPILLS S Historic Spill; engine waste oil to storm sewer; surface water contamination; December Historic Spill 663 ft. N Zone A Low Kelly Property 101 S. Butler St. LUST S CRS AUL RCRA-SQG UST U FINDS WIR BRRTS Closed LUST: Petroleum - contaminated soil; Conditional Closure with GIS Groundwater Registry; Noted that contamination was within 100 feet of a private well; March 2001.Closed/Removed UST: (2) 1,000-gal leaded gasoline; 1,000-gal waste/used motor oil; 4,000-gal leaded gasoline; June 1997; 1,000-gal fuel oil, July Closed LUST; GIS Groundwater Registry; Closed/Removed USTs 739 ft. NW Zone A Moderate to High E. Main St. UST U Closed/Removed UST: 1,000-gal fuel oil; June Closed/Removed UST 744 NW Zone A Low Settlement Place 525 E. Main St. FINDS , In FINDS database; Madison Water Utility Offices (523 E Main). FINDS database; Redeveloped, Multi- Family Housing 792 ft. N Zone A Low E. Wilson St. AST A Active AST: 210-gal diesel; back-up for generator. Active Diesel AST 832 ft. W Zone A Low Updated: 8/2014 Table 4.1 sheet 1 of 28 Printed: 10/17/2014 2:13 PM

31 Madison Water Utility TABLE 4-1 CONTAMINANT SOURCE INVENTORY SUMMARY WELLHEAD PROTECTION UNIT WELL 17 MADISON, WI August 2014 Map Site ID No. FirstSearch Map ID No. Owner/Location Database or Reference Source Existing, Potential, or Former Contaminant Sources Reported Status Approximate Distance to Unit Well 17 Location Within Capture Zone Estimated Threat to Well Madison Gas & Electric Co. 133 S. Blair St AST A LUST SPILLS BRRTS FINDS FTTS HIST FTTS Active AST: 600-gal diesel for backup generator. Closed LUST: petroleum - contaminated soil. Historic Spills: lorodifluromethane (R-22); gas escaped to air through broken bolt, June 2001; turbine oil spill, release to storm sewer and surface water, November 1996; Spill of unknown material, October Active AST; Closed LUST 838 ft. NE Zone A Low to Moderate Lake Terrace Building 121 E. Wilson St. BRRTS S Closed UST: petroleum; no contamination detected. Closed UST 857 ft. SW Zone A Low WI DNR Print Shop 125 S. Webster St S FINDS RCRA-NonGen WID FINDS database. RCRA-NonGen. RCRA Non-Gen 871 ft. W Zone A Low WI DNR GEF II Bldg. 101 S. Webster St. SPILLS S PADS WID FINDS , Historic Spill; leak or accidental dumping of antifreeze; April 1999; Mineral oil spill also noted, January FINDS database. Historic Spills 874 ft. W Zone A Low Madison Graphic Services, Inc. 120 E. Wilson St. FINDS WID RCRA-NonGen Handler of hazardous materials; does not presently generate hazardous waste. FINDS Database; RCRA NonGen of Hazardous Waste 896 ft. SW Zone A Low Block Railroad St. UST U Closed/Removed UST: 1,200-gal kerosene; August Closed/Removed UST 915 ft NW Zone A Low Wisconsin Foundry and Maine Co. 623 E. Main St FINDS , Listed in FINDS database; Environmental Activity & Industrial Site. Active 975 ft NE Zone A Low WI Dept of Admin. / Munz Corp 101 E. Wilson St FINDS , LUST S FINDS database. Closed LUST: petroleum - contaminated soil; October Closed UST: 4,000-gal fuel oil; soil contamination; filled with inert material; May FINDS Database; Closed UST/LUST 982 ft. SW Zone A Low Doty Ramp 205 E. Doty St SPILLS S Historic Spill; October 1987; Petroleum - contaminated soil and groundwater. Historic Spill 0.16 mi. W Zone A Low King St. UST U Closed/Removed UST; 500-gal fuel oil; petroleum - contaminated soil; January Closed/Removed UST 0.16 mi. W Zone A Low Glendale Development Security State Savings Bank 118 King St. LUST S WI WRRSER Closed LUST; petroleum - contaminated soil; Returned to DNR jurisdiction from Department of Commerce in July Closed LUST 0.20 mi. W Zone A Low Updated: 8/2014 Table 4.1 sheet 2 of 28 Printed: 10/17/2014 2:13 PM