Living with Karst in Rochester, MN Rochester’s Destination Medical Center . The Sinkhole Conference Oct 5-9, 2015 Rochester, MN by Jeffrey S. Broberg, LPG, REM: WSB Associates, Inc. • Others worthy of mention in local government service are Barb Huberty, formerly of the County and City of Rochester who has worked to make sure the public and local decision makers understood our hydrology when facing development decision ranging from the closure of old dumps, citing of-the-of-the art landfill or stormwater Introductions management standards. Also Terry Lee, Olmsted County Environmental Coordinator raised community awareness about the Decorah Edge and the risks and benefits of groundwater discahge on local hillsides. • I am Jeffrey S. Broberg, Minnesota Licensed Professional Geologist • Our community has greatly benefited from the scientific revelations #30019 . I graduated from the University of Minnesota in 1977 and made by the Minnesota Geologic Survey and United States Geologic spent the next 10 years in Lafayette Louisiana, riding the boom and Survey. Both agencies have allowed devoted scientists to develop a bust of the second OPEC Oil crisis. I moved back to Minnesota and large body of work that makes Rochester a safer and more prosperous have practiced as a geologist and environmental/geotechnical place. Jeff Delin, Richard Lindgren and Perry Jones of the USGE consultant in Rochester since 1990 with McGhie & Betts deserve particular mention. At the MGS Tony Runkel, bob Tipping and Environmental Services, now WSB Associates, Inc.. After 25 years in SE Julie Steenberg also deserve credit. I have borrowed extensively from Minnesota I have worked professionally on nearly every type of karst their work in preparing his guidebook. hazard the regional has to offer and I was happy to have the opportunity to share may experiences on a short filed trip around • The Minnesota Department of Natural Resources and the university of Rochester. Minnesota are important contributors to our knowledge of the local karst. Jeff Green, DNR Karst hydrologist and Scott Alexander, UofM researcher have both made great contributions. • Having been acquainted with Dr E. Calvin Alexander for almost 40 • I want to thank all of my co-workers and friends at McGhie & Betts and years we have shared many sinkhole and karst occurrences ranging WSB Associates, Inc. Bill Tointon, Dave Morrill, Luke Lunde and many from the collapse of the Bellchester Sewage lagoon, to the current others have helped shape Rochester using the best available crisis of nitrate contamination of our groundwater. I owe Calvin a debt information and resources. I also want to thank WSB Associates, Inc. of gratitude and would like to dedicate this trip to him and his For their growing commitment to Rochester and their contribution to revealing work, his willingness to share, teach and advance Karst the production and printing of this guidebook. Science • Finally I want to thank the Minnesota Groundwater Association • There are many others who deserve acknowledgemaent and credit for (MGWA), a group of dedicated professionals who are constantly advancing the understanding of karst I n the Rochester, MN area. First seeking ways to advance our understanding and care of Minnesota’s Olmsted County, City of Rochester and the surrounding Townships groundwater resources have always embraced a science-based approach to land use and land development, where karst meets local citizens. Rochester Public Utilities, and the water mangers there have been leaders in developing the science and funding the studies of Hydrostratigraphy and water quality in a region where everyone relies on healthy drinking water.

Introduction and Acknowledgements 2 Rochester, MN sits in the Zumbro River Valley at the confluence of nine sub- Fissile carbonates resulted in a fractured and dissolved subterranean aquifer watersheds that drain the glaciated plain to the west and drains the bedrock system dominated by rapid conduit flow with sinkholes and fractures near the controlled karst landscape to the east. Carved into the Paleozoic Plateau the City surface, funneling as much as 50% of the local precipitation into the sensitive

of Rochester is dissected by the eastern edge of the Wisconsin–age glaciation aquifers ,making the karst aquifers highly susceptible to pollution. where the DesMoines Lobe glacial ice ran past Rochester to the west and left the area to the east largely untouched. Rochester defines the eastern side of the Underlying the Galena dolomitic limestone the 90-foot thick is “Driftless Area” and while thin sheets of the Wisconsin glaciers covered parts of largely impervious to water, creating an aquitard that prevented the downward the Driftless Area, the lands to the east of Rochester are principally a bedrock percolation of groundwater. In the Driftless Area side-hill springs and seeps ring the controlled terrain covered by windblown loess soils ,while the the areas to the valleys where the fractured karst aquifers meet the impervious Decorah Shale west are a glaciated terrain dominated by glacial till and glacial outwash features. aquitard. Like lateral moraines and eskers. First Nation Paleo Indian hunters found chert for stone tools, fresh water springs The bedrock is a flat-lying sequence of Cambro-Ordovicain sedimentary rocks. The and shelter in the bedrock valleys and found abundant game in the wetlands, landscape from the beginning of the to the was a prairies and oak savannah hillsides. The combination of glaciated prairie and continental upland subjected to constant erosion and corrosion of the Paleozoic wetland terrain on the west, and a bedrock controlled landscape on the east, with bedrock leaving an ancient karst landscape millions of years before the glacial sinkholes and springs was a benefit for Early settlers who first occupied sand caves advance and sod houses near perennial springs. Their first homes and settlements used resilient flaggy fieldstone and rough hewn timbers and the rivers and sinkholes were To the south and east of Rochester the first encountered bedrock under the thin convenient for waste disposal. As Rochester developed the karst features clearly till and loess are the carbonates and shale of the . The Platteville provided benefits and risks. Limestone, Glenwood Shale, St. Peter Sandstone lie conformably under the Galena, but are separated by a 10my unconformity above the Prairie du Chein Now geologists, engineers and environmental managers are developing land use Group dolomite s which represent the basal rock units exposed in Rochester’s policy and defining development and building codes based on our growing Zumbro Valley. These rock units were all deposited in the shallow epiric seas near knowledge of karst. Developers, designers, engineers and geoscientists have the middle of the Hollandale Embayment. The , the youngest of learned the importance of hydrostratigraphy and how interbedded aquifers and the local blanket sands ,is present in the deep subsurface and serves as confining layers define the opportunities and risk for a rapidly growing, high-tech the local aquifer, but, is only exposed far to the north east and north end of community. Our 100 mile trip around Rochester will look at the historic benefits and Olmsted County, beyond the area covered in this tour. the risks and the view the current state-of-the-art of living on the karst. Jeffrey S. Broberg, Minnesota Licensed Professional Geologist During the glacial epoch the eroded surface of the carbonate karst was draped WSB Associates, Inc. with wind blown silty loess pushed out of the valleys in dunes across the Rochester, MN highlands. The combination of soils with a high water capacity overlying and the 2015 The Sinkhole Conference Rochester: in Karst Livingwith Introduction: Local Field Trip 3 Rochester Karst Fieldtrip Index • Page 2-15: Introduction: Geography, climate and geology • Page 15-20: Mile 0-6- Groundwater/Surface Water relationships. The St. Peter Recharge Plain-Decorah Edge- Galena Karst Plateau of Eastern Olmsted • Page 21-23: Mile 6-10- Rochester’s Flood Risk • Page 24-26: Mile 10-26- The Eyota Spring fields and Orion Sinkhole Plain • Page 27-28: Mile 26-39- The glacial edge of the Upper Root River Valley. Glacial seeps and calcareous fens. • Page 29-35: Mile 39-53- SW Rochester Karst Plateau. Mayowood sinkhole plan and Galena Quarry • Page 36-37: Mile 53-67- Salem glacial valley aggregates and Kalmar buried valley. Sand pits and Kalmar Landfill • Page 38-42: Mile 67-79- Rochester sandstone collapse sinkholes and Prairie du Chein karst: The St. Peter/PdC unconformity • Page 43-51: Mile 79-92- Prairie du Chein karst • Page 52-53: Mile 92-104- North Rochester drainageway sinkholes and Prairie du Chein karst. Rochester’s

historic riverside dumps. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Index 4

Sinkhole conference Route Map Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Google Earth Field Trip Route 5

Shaded relief from LiDAR DEM by Ben Ogren, WSB Associates, Inc. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Zumbro Watershed and surrounding Counties 6 The Zumbro River Partnership, a non-profit,

non-government Watershed partnership, is prioritizing critical restoration sites to raise awareness and funding to sustain an interest in Zumbro River water quality. The Zumbro River in Rochester is impaired for suspended sediments, nutrient enrichment, bacteria and mercury affecting aquatic life, aquatic recreation and aquatic consumption. The land use in this karst landscape is largely responsible for the

impairments. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: The Zumbro Watershed 7 Located at 44° North Latitude Rochester ahs

a temperate climate.

The HUC 8 Zumbro Watershed is 990,000 acres. The HUC 8 Root River Watershed is 1,064,961 acres and has 15 major subwatersheds The land was originally prairie, oak savannah and floodplain forests. Starting with early settlement in the 1850’s the land was converted to agricultural production and is now dominated by row-crop production

Edge of field studies recently completed in a Fillmore County partnership with the Minnesota Department of Agriculture measuring field to stream hydrology on cropland found • With 33” of precipitation/year runoff averaged only 2.9” a year, less than 10% of annual precipitation. The resto of the precipitation infiltrated into the soil and bedrock, evaporated or evapotranspirated. Over the 5-year study runoff varied from <0.1” to 9.2”/yr. • 46% of runoff occurs when the ground is frozen, typically in February and March. • Annual nitrate leaching losses varies from 6#-50#/acre/year

• http://www.mda.state.mn.us/protecting/cleanwaterfund/onfarmprojects/rootriverpartnership.aspx Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Local climate and surficial hydrology 8

Hydrochemical Survey of the Groundwater Flow in the Rochester Metropolitan Area, Minnesota, R. Tipping MGS OFR14-05, June 2014 Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Region relies on groundwater 9 East-side Escarpment Edge of Upper Carbonate Plateau and Decorah Edge: Marion Township

Geological Controls on Groundwater and Surface Water Flow in SE Minnesota and It’s Impact on Nitrate Contamination in Streams, Runkel, Steenberg, Tipping, Retzler, MGS

OFR 14-02 Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Layer-cake hydrogeology 10

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Hydrostratigraphy of interlayered confining beds 11 - MGS OFR 14-02

Unconformities and paleokarst horizons are interlayered with confining beds defining

local and regional hydrostratigraphy Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Unconformities in SE Minn 12 SE Minnesota Karst features:

Alexander and Gao 2002 Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Karst has been well defined in SE MN since before 2002 13

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: 2015 Watershed Management Efforts rely on karst information 14

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Rochester Wellhead Protection Plan 15 Decorah Edge Seeps, Land use and groundwater hazards.

Groundwater Recharge and Flow Paths Near the Edge of the Decorah Shale-Platteville-Glenwood Confining Unit, Rochester, MN. USGS Water Resources Report 00-4215,

Lindgren, 2001 Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Decorah Edge Studies 2001 16 Rochester’s proactive approach to groundwater management has involved multiple partnerships with state and federal agencies who have developed a sound understanding of local hydrostratigraphy and groundwater condition.

Ongoing efforts of RPU, MGS, DNR and USGS are detailing this karst sequence layered with confining

Rochester Public Utilities: Rochester Wellhead Protection Plan 2007 Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Rochester Groundwater susceptibility 17 The Galena Plateau and Decorah Edge rims the City of Rochester Isolated islands of Galena/Decorah have low water storage capacity with few side-hill wetlands and Decorah Edge risks, however the edge of the Galena/Decorah to the east, south and west of Rochester store and discharge high volumes of groundwater resulting in persistent springs, wetlands and headwater streams

Olmsted County Geologic Atlas. Bedrock Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

The Decora Edge: Rochester East side 18 Both Rochester and Olmsted County adopted Decorah Edge protection ordinances in 2006. Decorah Edge features with active hydrologic

elements, including wetlands, springs, seeps, fens and associated soil types cannot be disturbed by development except for Collector Streets and essential public utilities.

The combination of the risk of flooded basements fro m groundwater flow, shrink/swell of clays, frost heaving and unstable slopes on the Decorah Edge and the findings of the USGS and Olmsted County on the ability of the Decorah edge features to clean nitrate from groundwater led to wide community support for Ordinances to protect Decorah Edge features. Developers and builders welcomed clearly defined risk features and the new avoidance maps , stating that for too long they have been building homes that later developed structural damage, wet basements and mold. Public water supply mangers saw the Decorah Edge regulations as another groundwater protection tool.

Today developers and their consulting planners, and engineers refer to these maps and conduct field studies to refine the mapping in high risk areas. The dynamic nature of the seasonal groundwater flows make it important to recognize the geologic and soil features that indicate groundwater movement through the Decorah slopes. 2015 The Sinkhole Conference Rochester: in Karst Livingwith Rochester/Olmsted Decorah Edge Ordinance 19 A high density of homes served with individual septic systems (ISTS) 0n the Decorah Edge needed to address multiple ISTS failures and imminent health threats from septate discharge. A subordinate sewer district, funded with grants and assessments to property owners allowed this community to run

a pressure sewer line and connect to Rochester’s Waste Water Treatment Plant. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Chester Heights sewer district 20

Flood control project proves successful under heavy rain Posted: Jun 17, 2014 6:42 PM CST Jun 17, 2014 6:42 PM CST By Devin Bartolotta, Anchor/Reporter ROCHESTER, Minn. (KTTC) -- The Rochester flood control system is holding up after being put to the test

by heavy rains Monday night. Officials said this system has paid for itself time and time again, and that things could have been much worse Monday night without a sophisticated flood control system in place.

"It goes down to the Silver Lake Dam and then under the 37th Street bridge and out of Rochester," said Flood Risk Assistant City Administrator Gary Neumann. "Right now we've got quite a bit of capacity left in the system." 1987 Flood The Zumbro River charging through town after heavy rainfall is a sign that the Rochester flood control project is working.

It's a project that took nearly 40 years from start to finish, and it's the reason inches of rainfall no longer leave Rochester totally underwater. "It had a larger design than is typical because of the '78 flood. Most projects are just designed to handle 100 year flood," said Neumann.

Some might remember the Rochester flood of 1978. Rains caused the deaths of five people, tens of millions of dollars in damage, and waist deep water in some parts of the city. It was the push needed to get federal funding for the project, and days like Monday show it's worth every penny of the nearly $100 million cost.

Right now, water levels in reservoirs are holding back the water, just as they are designed to.

"We have seven reservoirs that hold back a lot of the water and then we have this channel project in the city. All of our reservoirs have more space to hold back a lot of water," said Neumann.

The highest flood level on the Zumbro River since the flood control project was back in 2010, and Neumann is hoping rainfall this week won't bring Rochester back to that level.

"If we don't get major rain, more than several inches, we should be alright," he said. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

21 Introduction: Zumbro River Flood Control Projects Save Rochester in 2010

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction: Rochester Water Primer 2014 22

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Introduction; Flash Flooding Is a Frequent Occurrence in Olmsted County 23 Stop 1: Springs defined early settlement patterns Perennial cold-water springs like Bear Spring were major resources for Native American and early settlers who relied on these resources of clean, cold water. Some of the earliest know Paleo Indian artifacts indicate that the nomadic tribes seasonally settled around the springs. The earliest European settlers sought land with springs and homesteaded these sites when land grant first became available in the Minnesota Territories in 1854-55. Jeff Broberg This site, the Bear Spring, is named for the first settlers who constructed a stone spring house to capture the spring for potable water and later for refrigeration to support dairy operations. Stone ruins around springs are common around local

headwater springs. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Stop 1: Bear Springs 24 Olmsted Geologic Atlas, MGS 1988 Stop 2 – Orion Sinkhole Plain: The Orion Township sinkhole plain is underlain by the Stewartville Limestone karst. Very thin loess soils, averaging less than five feet, cover a mature karst plain with sinkholes that appear to be pre-glacial or even Cretaceous age.

There are no streams or stormwater draingeways in this landscape; all excess precipitation infiltrates into the subsurface and rapidly mixes with the Upper Carbonate groundwater which is universally contaminated above the drinking water standard with more than 10 ppm nitrates.

Landowners and farm managers largely ignore Best Management Practices for 50 foot cropland sinkhole setbacks from row crops and farmers have been slow to adopt nutrient management practices that would minimize the risk of groundwater contamination by applying nutrients with split applications when plant uptake is most effective. The contaminated groundwater discharges to the headwater springs where nitrate levels commonly exceed 10ppm and have been noted as high as 40ppm.

Feedlots for cattle are a mixed blessing. Pastures with perennial vegetation reduces the need for fertilizers on row-crops, but, manure from confined feedlots can contaminate the groundwater with both nitrates and bacteria.

Orion sinkhole plain Stewartville Limestone bedrock 25

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Stop 2 Orion sinkholes: Google Earth Image 26 SW Olmsted County: Edge of till and loess drape

Olmsted County Geological Atlas, Surficial Geology Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Glacial till edge and loess draped landscape 27 Nitrates in • . Groundwater In 2014 the Minnesota Geological Survey Published Open File Reports 14-02 and 14-02 the authors synthesized LiDAR topography with the stratigraphy, hydrology, dye trace studies, water quality from wells, and base flow in streams and landuse data. The studies revealed the nitrate contamination risk of intensive row crop production over the karst of SE Minnesota. In general where row crops cover more than 60% of the landscape stream base flow nitrates exceed the drinking water standard of 10 ppm. The synthesis of topography, stratigraphic and hydrologic data, and the role of confining layers interbedded with fractured carbonates were shown to define the risk of aquifer contamination from a leaky system that relies on chemical crop nutrients and manure. The local farm operators seem to believe that it is acceptable to contaminate the water to grow crops and programs to change the trend are opposed or ignored by farmers, crop consultants

and farm commodity groups. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Stream Base flow Nitrate versus row crop production 28 SW Rochester bedrock Olmsted Geologic Atlas, MGS 1988 controlled plateaus and valleys Sinkhole risks: • Stewartville/Prosser Plateau Sinkholes Solution enlarged karst conduits allow wet loess soils to collapse into the bedrock cavities. These types of sinkholes are common in suburban areas at the top of the ridges to the east, south and west of Rochester where the vertical karst conduits are rarely more than 8” wide but can create impressive soil collapse features that appears to be a deep vertical shaft into the subsurface. • Basal St. Peter/Upper Shakopee catastrophic collapse sinkholes: The basal St. Peter, at the unconformity with the underlying Shakopee formation is prone to catastrophic sandstone sinkhole formation, especially in drainageway settings. Geotechnical borings often find low blow counts and sand cavities just above limestone residuum at the unconformity. The sand cavities can fail leaving impressive sinkholes at the surface. St. Mary's Mary Breigh Bldg. and the Prairie Crossing

sinkholes represent these sinkhole risks.. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Bedrock Plateaus in SW Rochester capped with Galena Limestone 29 In 1990 the Mayo heirs Ned Mayo, Maria Donovan and Dr. Charles Mayo The City favored development with small lots served by sewer and water and opposed Jr. decided that the time was right to develop the 200 acre ridge-top suburban development pitting the Mayo family and the Township against the City of overlooking Rochester that once was part of Dr. Charles and Dorothy Rochester. The suburban vision was approved by the County and the limits of City

Mayo estate, a sprawling 1666 acre farm complex surrounding the growth were set once the County and the City were convinced it was safe to develop Mayowood Mansion on the southwest side of Rochester. A large parcel homes on the karst. of river bluffs and rolling wooded hillsides once was home to the Mayo menagerie of deer, elk and buffalo, and award winning dairy cows, beef Geologic field investigations identified 39 sinkholes on the ridgetop and five thick loess cattle and Friesian horses. A working stone quarry on the east and dunes were identified as suitable areas for Community Waste Water Treatment cropland and forests on the west were pockmarked with sinkholes. The drainfields. A Special District Plat was developed that identifies the sinkholes . Mayowood Mansion, stables, dairy and other homes were at the toe of Rochester Township adopted a sinkhole Ordinance that defined sinkhole risks, setbacks the bluff where seeps and springs provide cold fresh water year-round. and specified the need for engineering and geologic studies for each building site and septic system. Clusters of homes on the bluff top ridges were served by Community Waste Water Systems for the clustered homes and pressurized mound systems for the estate lots and a plan was developed to develop 125 lots and to preserve over 200 acres of wooded slopes with the Decorah Edge, seeps and springs.

The City of Rochester Land Use Plan had designated the entire Mayo property for urban development served by municipal water and sewer, but, the Mayo family’s vision was for estate-style suburban homes served with on-site septic treatment and private wells. A land-use battle over the City utility extension plans focused on the risks inherent with building on karst. What was the appropriate density, disturbance and development? Sewer or septic systems? 2015 The Sinkhole Conference Rochester: in Karst Livingwith Mayo Estate 30

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

1991 Mayo Woodlands Sinkhole Inventory 31 Mayowoodlands karst: Suburban development 1990-2015 1991:note the sinkholes and liniments 2015:The sinkhole plain has largely been

north of Meadow Crossing Road developed with 125 high-value homes Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Mayo Woodlands: 120 suburban lots on a sinkhole plain 32 Mayowoods Sinkhole investigations and mitigations. The original sinkhole investigation was conducted in the Fall and Winter of 2001. Before LiDAR McGhie & Betts Geologists found that winter weather with a thin snow cover and low barometric pressure greatly assisted the sinkhole inventory. The closed landscape depressions in the Galena Group Cummingsville Fm. often opened in the bottom to a solution enlarged cavity that would blow warm moist air from the earth during falling pressure. The typical sinkhole excavation reveals an 8” to 2’ wide solution enlarged cavity. Some were large enough to present a safety hazard and were immediately sealed with grouted rip- rap. The Rochester Township Sinkhole Ordinance prescribed that a geologist or civil engineer evaluate the sinkhole risk and either require a structural and septic setback or design mitigation measures that are protective of the development and groundwater resources. All home foundations are reinforced concrete capable of spanning a 2 foot void. All the wells were drilled through the Cummingsville, Decorah, Platteville, Glenwood and St. Peter and were developed in the Prairie du Chein. Community Septic systems serve as many as 9 homes and individual septic systems are typically pressurized mounds. Jeff Broberg, WSB Associates, Inc

Jeff Broberg Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Mayo Woodlands Home building and sinkhole mitigation 33 Stop 3: Mayowood Quarry The Mayowood Quarry on CR8 operated since the mid 1930’s and was grandfathered into the County and Township Zoning Ordinance. Primarily producing crushed rock products for construction and road building the operator would blade off 8 to 20 feet of loess and the insoluble residue in the epikarst residuum before blasting an 85 foot working face , the pot run rock was crushed and stockpiled on the quarry floor. In 1990 the quarry was confined by the platting of Mayowoods South subdivision and the operator blasted deeper until the encountered the fat clay of the Decorah Formation rending the crushed rock unusable due to the high clay content. The Quarry operations ceased in 2005 and the property developer who had purchased the Mayo properties retained planners to devise restoration plans that ranged from plans to develop multi-family housing, a park or a solar garden; none of the plans were adopted. In 2014 the Township required a closure and restoration and a plan was developed to place as much as 10 feet of “clean fill” in the bottom of the quarry with the hopes of one day developing a higher use.

Jeff Broberg, WSB Associates, Inc Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Stop 3: Mayowood Quarry: Prosser/Cummingsville/Decorah 34 Mayo Cummingsville Quarry

• Cummingsville • Top of Decorah

McGhie & Betts/WSB Associates

McGhie & Betts/WSB Associates

Mayowoods 35 Olmsted County Aggregate Resources Almost all of the commercial, high quality sand and gravel aggregates in Olmsted county are found in the buried river and stream valleys draining the glaciated terrain and flow from the west where the glacail till and alluvium represented a high qualty source of sand, gravel and cobbles. The streams draining the Driftless Areas to the west have only Paleozoic carbonate, shale and sandstone, not suitable source materials except for very fine grained sand.

Upland sand and gravels are found in NW Olmsted County and are derived from eskers or stream terraces in the glacial outwash

channels. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Salem/Rochester Township Aggregates 36 “There’s a Proper Place for Your Waste in Olmsted County”

• In the last leg of the tour we will be passing by most of the existing and historic solid waste facilities that have served Rochester and Olmsted County. Currently the Olmsted County Kalmar Landfill, located over a deep buried bedrock valley filled with dense and impervious glacial till ,is a state-of-the- art landfill with a double composite liner and leachate collection system. Detailed geologic investigations following the publication of the Olmsted County Geologic Atlas in the mid 1980’s identified an area of Olmsted County not prone to the typical karst risks. Prior to Olmsted County committing to the Solid Waste-to-Energy (WTE) Incinerator and Kalmar Landfill the areas solid waste was buried in burn dumps and landfills along the Zumbro river and in the Oronoco Sinkhole Plain.

• . Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Olmsted County Kalmar Landfill 37 Mary Breigh Foundation In 2012 the Mayo Clinic decided to fill in the courtyard between the new Emergency Room and the historic Alfred building Covenant Located in what was a pre-development drainageway the first encountered bedrock was the basal St. Peter Sandstone near the top of the Shakopee formation, a known unconformity with an paleo-karst. Soil borings conducted for the foundation design found sandstone voids at a depth of 25-30 feet below the planned lowest floor elevation. Additional geotechnical investigations with borings and cores identified a clay-filled sinkhole extended deep into the sandstone/limestone unconformity. Numerous borings taking blow-counts found consolidated sand with 50+ blows.1.5 feet above loose sand that would have between 0 and 6 blows/1.5 feet. Engineers designed a caisson systems employing 80” diameter reinforced concrete pillars extended to the top of competent bedrock. Along the east wall, pictured to the left, caissons placed on 20 foot centers encounter the Pleistocene, clay filled, sinkhole and the sand cavities. On one line of caissons the depth to the hard bedrock varied from 22 feet to 108 feet deep. Excavations for the foundation to the lowest floor level of the abutting Alfred building found a 4.5’ void where the sandstone substrate had collapsed under the structural floor slab that was supported by caissons. We will view the cores and the drilling logs at our stop at Mayowoodlands.

McGhie & Betts (WSB Associates,, Inc.) Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

St. Mary’s Hospital: Mary Breigh Building paleokarst challenges 38 foundation engineers

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Soil borings through sand have low blow counts just above the limestone residuum at the unconformity 39

McGhie & Betts/WSB Associates

Vertical fractures intersecting the side of the caisson boring extend to large sand voids at the water table just above the limestone. Boring logs and photos by McGhie & Betts

(WSB Associates, Inc.) Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Mary Breigh Soil Boring and Caisson 40

McGhie & Betts/WSB Associates

McGhie & Betts/WSB Associates Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Sand cavities at the top of the Shakopee. 41

McGhie & Betts/WSB Associates McGhie & Betts/WSB Associates

Photo 3 taken 10-17-2012 This photo was taken from within the void under the tunnel on the south end of the Multiple cassions exposed voids at the St. Alfred Building facing east. In this photo you can see the poly vapor barrier above, the cemented sandstone on the east wall of the void and the partially exposed face

Peter/Shakopee unconformity of a concrete pier. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Mary Breigh sandstone voids. Photos by McGhie & Betts (WSB Associates, Inc. 42 Upland esker aggregates Terraces along glacial outwash valleys and eskers are concentrated in the drainageways that flow off the glacial edge from the west. Aggregate resources do not exist in the valleys that drain off the bedrock terrain. The eskers include aggregates from the Superior Lobe and agates as well as traces of gold have been found in the Oronoco area giving rise to the Annual Oronoco Gold Rush celebration

Shaded relief LiDAR DEM by Ben Ogren, WSB Associates, Inc. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

NW Olmsted Upland Aggregates 43 Prairie Crossing sinkhole collapse In 2006 a mixed use development on the east side of US 52, north of 65th Street was approved. A grading plan called for a future frontage road to parallel the highway with commercial lots on both sides of the road and called for the construction of a MNDOT stormwater pond fed by the storm sewers in the street. The grading filled in across a drianageway, down gradient of culverts under US52, that drained almost 1000 acres at the edge of the glacial advance. The alluvial sands of the drianageway overlay the basal St. Peter Sandstone, Geotechnical soil borings to the standard depth of 25 feet did not reveal any karst risks. Following a heavy rain in the fall of 2006 nine St. Peter sinkholes opened and drained the ponded water into the subsurface. The sinkholes were filled with over 2500 cy of fill. The development never came to fruition due to the recession. Three sinkholes collapsed again during a snow melt in the winter of 2008. In 2012 as part of the new 65th St NW highway interchange the sinkhole mitigation design by McGhie & Betts (now WSB Blocked drianageway Associates) uncovered 11 soil breccia pipes. Concrete taken from the 2nd St Reconstruction was used to fill a mushroom cap over the breccia pipes and the concrete slabs were grouted, then covered with sand followed by a foot of impervious clay. The drainage was rerouted so tat no ponding would occur in the old

drainageways Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Prairie Crossing Plat 44

2006 Sinkhole 5. Original Collapse 2008 Sinkhole 5. Second collapse

McGhie & Betts/WSB Associates McGhie & Betts/WSB Associates

McGhie & Betts/WSB Associates Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Prairie Crossing Sinkholes. 45

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Prairie Crossing Sinkholes 46

McGhie & Betts/WSB Associates McGhie & Betts/WSB Associates

McGhie & Betts/WSB Associates

McGhie & Betts/WSB Associates Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Sinkhole excavation and mitigation 47 Oronoco Landfill • .

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

1989-90 Oronoco Landfill 48 Dye Trace, Alexander, Alexander, Huberty and Quinlin

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

1989-90 Oronoco Landfill 49 Dye Trace, Alexander, Alexander, Huberty and Quinlin

Shaded relief LiDAR DEM by Ben Ogren, WSB Associates, Inc. Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Bedrock draped with loess east of Lake Zumbro 50

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

MGS OFR 14-02 Zumbro River Hydrostratigraphy 51 Basal St. Peter sand • . collapse Excavation in north Rochester often encounters the base of the St. Peter, just above the unconformity. In 2002 the Chateau Theater sought a grading permit to carve out a flat site. At the time City Ordinance required maximum 4:1 slopes for excavations. Geotechnical evidence was presented to prove that the round sand grains of the St. Peter Sandstone were not stable at 4:1 slopes showing numerous local examples of landslides where soils and vegetation on these shallow slopes has suffered translational failures. New rules were adopted to allow near vertical sandstone slopes with terraces. During the excavation a large breccia pipe was revealed in the middle of the slope. The breccia was not cemented and immediately began sloughing. The remainder of the slope has been

stable for Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

St. Peter breccia pipe – chateau theater 52

Waste Disposal History

History of Olmsted County Solid Waste Disposal: In the 1920’s the Mayo’s concerned with public health insisted on having a single place to dispose solid waste. In an era when most people burned their rubbish in burn barrels and businesses dumped their refuse in the Zumbro River Rochester Opened the Rochester Burn Dump on North Broadway at what is now Elton Hills Driver. The Burn Dump filled a bedrock ravine in the Zumbro River. A full time attendant titled the “City Scavenger” was responsible to extract all the recyclable metal and rags and burn the rest. In the late 1950’s the acrid smoke upset neighbors in Indian Heights and the City closed the dump in 1958 In 1958, the year IBM came to Rochester, until 1972 the City Dump filled the floodplain and banks of the Zumbro River, north of the then new Waste Water Treatment Plan on West River Road and 41st NW The dump operators dug sand pits in the river alluvium below the water level and used the sand for cover filling the resulting ponds with wastes from IBM and burned the municipal waste. Recycling was a forgotten practice. Due to the flood risk, the growth of Rochester to the NW, the limited space and the regulatory responsibility of the County to be the waste authority the dump was closed in 1972. In 1972 the City opened the Oronoco Landfill in a karst drainageway in the Oronoco Sinkhole Plain where numerous Prairie du Chein sinkholes had already been filled with refuse from the surrounding Township. Employing the practices of the day the soils were stripped from the site for use as landfill cover and the waste was packed and covered. Landfill leachate rapidly entered the groundwater that was the drinking water supply for the surrounding homes and the town of Oronoco. One of the first major dye trace studies in Minnesota proved the leachate risk. The landfill was transferred to Olmsted County and was closed in 1990 when the Kalmar Landfill and Waste- to-Energy incinerator were complete. Currently the WTE, located near the beginning of our trip, burns the waste and the ash is disposed in the Kalmar landfill which also accepts

overflow, industrial wastes and demolition debris Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Former Rochester City Dump 1920-58 53 Road Log: Zumbro River to Bear Spring

• Start: 0.0 mile Rochester Civic Center – South Branch Zumbro River. (East on Center St. To CR9) • Mile 1.2 Olmsted County Campus including Waste-to-Energy steam and electric generating facility (East on CR9) • Mile 2.1St.Peter Sandstone, Glenwood Shale, , Decorah Shale CR22 road cut • Mile 3.3 East Side Wildlife Management Area, Rochester groundwater mound (CR9) • Mile 4.4 Decorah Edge Seeps. USGS/Rochester Public Utility (RPU) monitor well sites (South on CR 11) • Mile 5.0 Groundwater flooded basements (East on US14) • Mile 6.7 Chester Subordinate Sanitary Sewer District (US 14 and CR119) • Mile 8.4 Olmsted County Chester Woods Park and Rochester Flood Control Reservoir • Mile 10.4 Milestone US14 Galena Quarry • Mile 11.1 Bear Creek headwater former trout stream drained and converted to croplands (South on 110th Ave) • Mile 11.8 Wetland seeps and fens

• Stop 1: Mile 12.4 Bear Spring – Historic Spring fed milk house and trout pond (West on 30th St SE to CR23) Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log:: Start to mile 12.4 54 Road Log: stop-1,Bear Spring to Cummingsville North Branch Root River • Mile 14.3 Galena Cummingsville Formation Springs elev. 1230-40 (south on CR23 to CR19 South) • Mile 15.0 Feedlot Springs elev. 1220-1230 (CR19 and I90) • Mile 16.0 Zumbro River/Root River Watershed divide elev. 1287 (CR 19 to US52 west) • Mile 17.0 Orion sinkhole plain surrounded by cropland (82nd Ave SE • Mile 17.5 Orion Sealed sinkhole (South on 82nd ,Ave SE) • Stop 2 Mile 17.9 32nd Ave Orion Twn. Roadway dissecting sinkhole • Mile 18.1 Orion Sinkhole Plain surrounded by cattle pasture and cropland (East on 70th St SE) • Mile 19.2 Shoenfelder Cattle Feedlot (South on CR129) • Mile 21.1 Hog confinements • Mile 21.8 Road cut Stewartville Fm. to St. Peter Fm. (East on North Branch Rd SE)

• Mile 23.2 North Branch Root River Cummingsville (south on CR7SE then West on MN 30) Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log: Mile 14.3-23.2 55

Road Log: Cummingsville to Mayowood

• Mile 25.5 Dairy Confinement and manure pit (continue West on Mn30) • Mile 26.2 Loess Plain over Galena Karst/edge of Wisconsin till • Mile 35.3 Maple Brook Subdivision springs. Golf course converted to urban subdivision (North on US63) • Mile 36.2 Stewartville North Branch Root River (US 63 North) • Mile 39.3 Airport Calcareous Fen. • Mile 41.3 Cummingsville Fm. Road cut. Distinctive saw-toothed exposure • Mile 42.3 Decorah road cut and slope failures mitigated with rip-rap buttress • Mile 43.5 Willow Creek aggregates. (SU63 and 40th St SW) • Mile 43.9 St. Peter Castellated Dome • Mile 44.4 Willow Creek Groundwater Mound • Mile 45.9 US52 Decorah Shale Road cut (North on US52) • Mile 46.9 South Branch Zumbro River Aggregates (West on 16th St. SW then North on CR8) • Mile 48.6 Platteville fountains and Decorah seeps and springs – (CR 8 and Maryhills Dr.) • Mile 50.0 Mayowoodlands Sinkhole Management District (West on Meadow Crossing Road) • Stop 3. Mile 53.6 Maywood Galena Quarry. Prosser/Cummingsville/Decorah (North on CR8 then West on CR117)

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log Mile 25.5-53.6 56 Road Log: Mayowood to Prairie Crossing Sinkhole Collapse • Mile 55.7 Heritage Hills Seeps and Springs • Mile 56.7 Flooded basement from Decorah Seeps. Mold and property damage (North on 104) • Mile 57.3 Salem buried valley aggregates • Mile 57.8 South Fork Zumbro River (West on CR 25 then North on 70th Ave SW • Mile 59.4 Glacial Till edge (West on CR34 ) • Mile 62.6 Buffalo Ranch (North on CR3, cross US14 and North to 19th St NW) • Mile 66.1 Olmsted Kalmar Landfill. Buried glacial valley 300’ to bedrock. • Mile 67.0 Kalmar Flood Control Reservoirs (Continue East to CR104 go south) • Mile 69.3 Kalmar Decorah Edge City of Rochester Urban Service Limits (cross US14 then go East on CR34 (2nd Ave SW)) • Mile 71.1 St. Peter road cut • Mile 71.5 Cascade Creek Flood Plain. Golf course conversion to urban subdivisions • Mile 71.7 Cascade Creek Aggregate Pits. Cascade Lake Park (2nd Ave SW and Avalone Cove Dr) • Mile 72.8 St. Mary’s Hospital Mary Breigh Building Foundations on sinkholes (North on 11th St NW) • Mile 73.8 Cascade Creek (West on Civic Center Dr) • Mile 74.4 US 52 with Assissi Heights on hill to the right (North on US52) • Mile 76.3 IBM Rochester (US52 at 41st St NW) • Mile 77.3 Car lot St. Peter sinkholes along Kings Run

• Mile 79.2 Prairie Crossing Blocked Drainageway Catastrophic sinkhole collapse (US 52 between 65th and 75th St exists) Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log Mile 55.7-79.2 57 Road Log: Mile Prairie Crossing to US 63 Castellated Domes • Mile 80 Glacail Outwash valleys and terraces (East on 75th then North on 18th Ave NW) • Mile 88.2 Oronoco Prairie du Chein sinkholes. (18th St NW and 85th St NW (CR154)) • Closed Oronoco Landfill 1972-1990 beyond trees to the west • Mile 83.3 Oronoco Prairie SNA native short grass prairie (West on 100th St NW (CR112)) • Mile 84.5 Esker pits and mines (North on 2nd Ave SE) • Mile 85.86 Oronoco Wells and Septic. New subdivisions have community waste treatment • Mile 86.6 Original small lots have no septic reserve. New Oronoco water system protects drinking water • Mile 86.9 Oronoco Shady Lake Dam: Destroyed by historic 2010 Flood. 30 foot flood (East on 5th St SE) • Mile 87.8 CAPX2020 (East on CR 12) • Mile 89 Rucker Hog Lot: Sinkholes identified in 2010 EAW stopped feedlot expansion • Stop 4 Mile 91.1 White Bridge Road Cut: Prairie du Chein Karst • Mile 92.3 Loess Dunes (CR 12 and US63 South)

• Mile 95.1 US 63 St. Peter/Glenwood/Platteville Castellated Domes Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log Mile 88.2-95.1 58 Road Log: US63 Castellated Domes to Civic Center • Mile 96.9 St. Peter Road cut • Mile 100.4 Hadley Creek Valley • Mile 101 Historic Rochester City Dump in floodplain of Zumbro River 1 mile west 1958-1972 • Stop 5 Mile 101.4 St. Peter breccia pipe. Paragon Chateau 14 Theater slope excavation (Left into Shopko Lot) • Mile 101.8 Sealed St. Peter caves (6th Ave NE to Wellner Dr, South on Broadway (US63) • Mile 102.9 Rochester Rec Center/Senior Center. Historic Rochester City Dump (Broadway and Elton Hills Drive NE) Mile 102.6 Historic Rochester City Dump 1920-1958 • Mile 103.3 Silver Lake Dam • Mile 104.3 Broadway and Center Street. Mayo Clinic 2 blocks west • Mile 104.4 Return to Civic Center

Living with Karst in Rochester: The Sinkhole Conference 2015 The Sinkhole Conference Rochester: in Karst Livingwith

Road Log Mile 96.9-104.4 59