14374_covers 2/9/04 9:00 AM Page 2 14374_covers 2/9/04 9:00 AM Page 3 A User’s Guide to Karst and Sinkholes in Western Maryland By Topper Sherwood WESTERN MARYLAND RC&D 18450 Showalter Road, Suite 111 Hagerstown, MD 21742-1383 Voice: (301) 733-2973 Fax: (301) 733-7643 E-mail: [email protected] URL: users.erols.com/wmarylandrcd/ PUBLISHED: JANUARY 2004 This guide was published with funding from the Chesapeake Bay Small Watershed Grants Program of the National Fish & Wildlife Foundation (www.nfwf.org/). Thanks to all the par- ticipants in Western Maryland RC&D-sponsored meetings on karst and sinkholes in our region: Mark Seibert, NRCS District Conservationist, Frederick Field Service Center; Tom Devilbiss, Hydrogeologist, Carroll County; Tom Gray, GAI Engineer, Pittsburgh, PA; Sabrina Albright, Western Maryland RC&D; Ann Brown, Frederick County Grants Office; Ed Sanders, Maryland Department of Agriculture; Gerald Baum, Maryland Geological Survey; Liana Dunne, Maryland Geological Survey; David K. Brezinski, Maryland Geological Survey; Paul Petzrick, Maryland Department of Natural Resources; Douglas A. Valentine, NRCS District Conservationist, Carroll Field Service Center; Jim Schlossnagle, NRCS District Conservationist, Washington County Field Service Center; Terry Welsh, NRCS Soil Conservation Technician, Frederick Field Service Center; and Dawn Early, Soil Conservation District Manager, Frederick Field Service Center. Special thanks for their attention to and comments on this guide to: Tom Devilbiss; Western Maryland RC&D Secretary-Treasurer Paul Edwards, and Carl Robinette, NRCS District Conservationist, Allegany Field Service Center, and many county employees in the region. This guide was printed on 100% recycled paper by HBP, Inc. in Hagerstown, MD 14374_book 1/30/04 11:59 AM Page 1 A User’s Guide to Karst and Sinkholes in Western Maryland By Topper Sherwood Western Maryland Resource Conservation & Development Council, Inc. Hagerstown, MD 1 14374_book 1/30/04 11:59 AM Page 2 CONTENTS INTRODUCTION: Why This Guide? 3 What is Karst Topography? 4 Maryland’s Karst and Sinkholes 5 Karst, Land Use, and Water 5 Myths & Facts about Karst & Sinkholes 8 Problem : Runoff 9 What You Can Do 10 Septic Systems and Karst 10 What You Can Do 11 Protecting Well Water 11 What You Can Do 13 Sinkholes and ZOIs 13 Dealing with Problem-Causing Sinkholes 14 Agriculture on Karst 15 What You Can Do 16 MACs & BMPs 15 What To Do If You Suspect a Sinkhole 16 Local Resources 19 Resources for Disposing of Household Waste 21 Note: The photos in this guide are of Western Maryland karst and sinkholes. The back cover, however, shows an enormous Mexican sinkhole, El Sotano de las Golondrinas (“Cellar of the Swallows”). 2 14374_book 1/30/04 11:59 AM Page 3 INTRODUCTION: WHY THIS GUIDE? This guide was written to help people The Western Maryland RC&D is who live and work in Maryland to be grateful to all the partners who have more aware of the issues presented by joined in the development of the guide, karst topography, a geological terrain which was supported by a Chesapeake whose most well-known characteristics Bay Small Watersheds Grant from the are solution cavities, caves, and National Fish & Wildlife Foundation sinkholes. (www.nfwf.org). The developers of this guide We are also grateful to those who represent local agencies that assist read this guide, those who use the residents and business owners with information offered here, and to those questions about land, water, and karst. who share it with others. We work to help others understand the nature of land and water in our region, and to become more aware of the need for good conservation practices. We have developed this guide to be of specific use to: • residents — farmers and home owners who live and work in karst areas; • mortgage and real-estate professionals; • state and local policy makers and planners; • insurers; • educators; • members of the media; and • construction and utilities contractors. Questions about karst and sinkholes can be directed to members of the Hutzell agencies listed on pages 16-20 of this Doug guide. Questions and comments about the guide itself should be forwarded to the Western Maryland Resource Conservation & Development Council (RC&D). 3 14374_book 1/30/04 11:59 AM Page 4 WHAT IS KARST TOPOGRAPHY? “Karst” describes terrain that’s characterized by sinkholes, caves, underground streams, and other features that are formed by the slow dissolution of calcium and magnesium oxides in Sherwood limestone, dolomite, or marble bedrock. Karst landscapes are often spectacularly Topper scenic areas. Examples include the falling into them, as well as the danger to sinkhole plains and caves of central structures — buildings, roads, airport Kentucky, the large crystal-clear springs runways, etc.; and 2) the threat to ground of Florida, and the complex, beautifully and surface water quality by the potential decorated caves of New Mexico. Karst for direct introduction of contaminants. terrains are areas of abundant water People living and working in karst regions supplies, limestone quarries, and minerals. need to be particularly sensitive to issues In the United States, 20 percent of the of land use and water quality protection. land surface is karst and 40 percent of the The stakes are high for communities groundwater used for drinking comes confronting the physical danger of from karst aquifers. sinkholes. Recent collapses have been People who settle in karst areas, occurring along Interstate 70, in Frederick however, can find themselves dealing with County, and one sinkhole that opened associated problems. Karst regions can be suddenly on a state highway in Carroll prone to unpredictable or easily County in 1994 caused a fatal auto contaminated groundwater supplies or accident there. Sinkholes appearing in unusual surface water drainage. Karst fields have injured livestock and damaged landscapes are also among the most farm equipment. The threat to water susceptible to environmental impact, quality is well documented and can pose a including ground subsidence. Following significant and quick hazard. Stream storms, droughts, and changes in land use, water or surface runoff that enters a sudden subsidence features known as sinkhole or cave can bypass natural sinkholes, can cause damage to buildings, filtration through soil and sediment. roads, parking lots, and farmed land. Groundwater can travel quite quickly In unpopulated and undeveloped areas, through these underground networks —up a sinkhole may pose little or no danger. In to thousands of feet per day — carrying populated and developed regions, surface contaminants to wells and springs. however, sinkholes are more likely to We will discuss this issue further in the cause problems. They present us with two section on water quality, beginning on kinds of hazard: 1) the physical danger of page 5. 4 14374_book 1/30/04 11:59 AM Page 5 MARYLAND’S KARST interpretation table outlining the relative AND SINKHOLES potential for sinkhole formation by soil series.] Where are Maryland’s karst areas? MGS staff members estimate that The most-affected counties are Frederick County alone contains a Washington, Carroll, Frederick, and vulnerable karst topography covering Baltimore, with less extensive areas in about 35 square miles. Washington Allegany County. (See Figure 1. below) County is estimated to have a karst area While we cannot know every detail of of two or three times that size. The what lies in the ground below every Geological Survey has identified more piece of property, geologic mapping by than 1,000 “karst features,” including the Maryland Geological Survey (MGS) 125 sinkholes, in a relatively small has provided an excellent understanding portion of Frederick County. From this, of Maryland’s subsurface. [For access to we know that hundreds of sinkholes are MGS maps and other information, visit likely to exist in each of the three most- www.mgs.md.gov.] affected counties, Washington, Soil surveys conducted by the Frederick, and Carroll. National Cooperative Soil Survey also provide clues to potential areas of Karst, Land Use, and Water sinkhole development. Soil maps Quality identify areas where soils originate from or overlie limestone and other material All uses of land affect an area’s with some potential for developing groundwater. Those of us who live and sinkholes. To access soil survey maps work in karst country, however — and interpretive information, visit homeowners, real-estate professionals, www.sawgal.umd.edu/nrcsweb/Marylan public planners, farmers, or contractors d/index.htm and navigate to a particular — should be especially aware of the county. [The current Frederick County terrain’s tendency to form sinkholes and Soil Survey (2002) contains a soil- the implications for our water resources. Most karst areas are underlain by limestone which may be composed of varying degrees of openings. Sometimes large, sometimes small Figure 1 most have the ability to transmit water and soil. Sinkholes occur when a 5 14374_book 1/30/04 11:59 AM Page 6 “bridge” of loose stones and soil untreated surface water, directly and collapses into a fissure or opening in the immediately, to local aquifers affecting rock, sending surface material and water any number of springs, and well sources. into underground cavities. (See Figure 2 Sinkholes may threaten water quality, on the opposite page.) Such sinkhole for example, when they occur near collapses occur naturally; they also may underground water and sewage systems. be prompted