Gerald L. Mahan
A.Wayne Jones
Kristina M. Boone
Larry C. Brown
Water stored under the earth's surface is a plentiful, yet precious, resource in most areas of Ohio. Human activities greatly affect ground water. However, the availability and quality of this resource are influenced directly by the properties of the geologic formation that holds water. The chemical and physical nature of these formations varies from area to area, creating a wide range of water yields and quality at different depths. This publication contains information about the ground-water resources underlying Greene County. Its purpose is to help the reader better understand the factors that influence the quantity and quality of ground water. Water resources terminology used in this publication is included in Surface and Ground Water Terminology, fact sheet AEX-460, which provides a listing of generally accepted water resource definitions. Fact sheet AEX-460 and the publication Greene County Water Resources, AEX-480.29, are available through your county Extension office.
Geologic formations (e.g., sand, gravel, limestone, sandstone) have the ability to receive, store and transmit water. In general, if a formation is capable of yielding enough water to support a well or spring, it is called an aquifer. The earth materials from which a formation is composed influence its ability to store and transmit water. For example, sands and gravels allow water to flow through easily. By comparison, shale, which originated from compacted layers of mud and clay, generally allows very little water to flow through it unless the shale is highly fractured.
The carbonate aquifer, which is composed of limestone and dolomite, is a water source in eastern Greene County. Limestone consists of fossilized sea shells, shell fragments and consolidated limy mud deposited in ancient inland seas. Its main mineral is calcium carbonate, CaCO3. Dolomite is similar to limestone but has few recognizable fossils. Its main mineral is calcium magnesium carbonate (Ca,Mg)CO3. Both limestone and dolomite are commonly referred to as limestone. These limestone and dolomite formations were deposited in a shallow inland sea between 400 and 500 million years ago. Deposits commonly range from 25 to 300 feet deep. The bedrock in the western portion of the county consists of interbedded shale and limestone. The low yielding nature of this bedrock produces a large number of dry holes.
Unconsolidated deposits in Greene County consist of glacial till, sand, gravel, silt and clay, all of which were deposited by some form of glacial action. Glacial till, which is an unsorted mixture of clay, sand, gravel and boulders, will not yield much water. However, lenses of sand and gravel within the glacial till and coarse outwash materials are capable of yielding substantial quantities of water.
The actual yield of a well, in gallons per minute (gpm), will vary considerably depending on the age and depth of the well, the diameter of the casing, well construction, pump capacity and age, and most importantly, properties of the geologic formation. The exact yield and depth of each well will depend on the properties of the geologic formation at the specific location of the well.
The Ohio Department of Natural Resources (ODNR), Division of Water, maintains a statewide data base of more than 700,000 well logs. The Ground-Water Resources Section of the Division manages this valuable data base, which includes some information collected by the U.S. Geological Survey (USGS) and the Ohio Environmental Protection Agency (Ohio EPA). Since 1948, well log information has been collected to increase the understanding of ground-water resources in Ohio. Geologists and hydrogeologists continue to study the state's ground-water resources, and as a result, Ohio is one of only a few states that has been completely mapped for ground-water availability (mapped by river basin, from 1959 to 1962).
Estimates of the size, shape, geologic makeup and yields of aquifers are being mapped county by county. Most of Ohio's counties have a completed ground-water resources map. The map presented in Figure 1 is a generalized representation of the water-bearing formations underlying Greene County (adapted from map by Schmidt, 1991). This illustration is based on a hydrogeologic interpretation of the well log data from Greene County and surrounding areas. It should be used only as a guide to understanding the ground-water resources in the county. Figure 2 presents a generalized cross section of Greene County (referenced in Figure 1 as line X-X') illustrating the valley fill in the Little Miami River and Beaver Creek areas. The "?" in Figure 2 indicates that sufficient data have not been collected to properly characterize these specific locations. The remainder of this section provides a brief description of the types of aquifers illustrated on the map in Figure 1.
Figure 1. Ground-water resources of Greene County, Ohio (modified from J.J. Schmidt, ODNR Division of Water, by R.A. Roberts).
Figure 2. Generalized cross section of valley fill in Greene
County, Ohio (modified from Underground Water Resources map,
K-1, ODNR Division of Water).
Area B illustrates sand and gravel deposits at a depth of about 80 feet. Well depths range from 30 to 190 feet, and yields of up to 500 gpm are possible.
Water-bearing deposits of sand and gravel above the limestone aquifer, shown as Area C, have been developed in eastern Greene County. A substantial amount of sand and gravel is present, which provides well yields of up to 75 gpm in glacial deposits that may be as thick as 150 feet. Most wells constructed in the sand and gravel average 75 feet deep.
Water-bearing sand and gravel deposits are interbedded with thick layers of glacial till are shown as Area D. Wells may be as deep as 235 feet, although most wells average 125 feet in depth. Yields from properly constructed wells in this aquifer system can be as great as 75 gpm. Sand and gravel may be found as independent lenses within the extensive glacial till deposits.
The limestone aquifer shown as Area E in eastern Greene County is part of a larger regional carbonate aquifer that underlies much of western Ohio. Relatively shallow limestone will yield up to 20 gpm. Well depths are less than 95 feet; deeper drilling will encounter the underlying, non water-bearing shaley limestone. Most water from this aquifer will require some form of treatment to reduce hardness and iron.
Area F illustrates a thin, low-yielding limestone aquifer underlying thin, clay-rich glacial deposits that result in a low-yielding area. Well yields of less than 10 gpm can be expected. Deeper drilling will encounter non-water-bearing limestone and shale. Increased storage may be necessary for peak water use periods.
Till over Bedrock Thick, clay-rich glacial deposits, illustrated as Area G, have potential yields of up to 10 gpm. Most of the limestone below the glacial sediments has been eroded away leaving only non-water-bearing bedrock. Well depths can vary from 35 to 300 feet. Cautious drilling is necessary to provide even meager yields, although some properly constructed wells have produced may produce a greater yield.
Non-water-bearing bedrock underlies thin, clay-rich glacial till deposits in Area H. Yields of less than 3 gpm may be developed. Any water available usually is found at the contact between the glacial materials and the bedrock. Water storage facilities may be necessary for residential use.
The water level in any well typically does not remain constant, but changes depending upon the proximity of adjacent wells and surface streams, and natural rainfall. Ground-water discharge and recharge greatly affect water levels in wells. The ODNR Division of Water monitors ground-water levels in three wells in Greene County, all located north of Xenia. Observation wells GR-1, GR-10 and GR-11, shown on Figure 1, are three of a number of wells throughout southwestern Ohio used to monitor the natural seasonal fluctuation or the effects of nearby pumping on the aquifer water levels. The water levels in GR-10 have held fairly constant for the period of 1980 to 1991, while GR-1 has shown a slight decline in water level over the years. Well GR-11 has only been in existence since March 1988. None of these observation wells have been in existence long enough to detect long-term extremes in water level.
Various state and federal agencies have participated in programs to determine ground-water quality in Ohio. In Greene County, water-quality data for five wells were available from the ODNR Division of Water. In Figure 1, these wells are noted as Chemical Analysis Sites 1 through 3, and are either industrial, public or domestic wells. Data were also available for observation wells GR-1 and GR-10.
The results of some of the chemical tests performed on these Greene County wells are given in Table 1. The chemical constituents listed are total dissolved solids, hardness (as CaCO3), hydrogen sulfide, iron and sulfate. All concentrations are given in parts-per-million (ppm). For comparison purposes, drinking water-quality standards for these chemical constituents are also shown. These standards are established by the U.S. Environmental Protection Agency (USEPA) for public water systems for aesthetic reasons (taste, odor, appearance, etc.), and are not enforceable. These chemical constituents do not pose a risk to human health (see notes in Table 1). There are no drinking water-quality standards for private wells.
The information in Table 1 can be used as a guide to what one might expect from an existing or new well. Even though four of the five wells were developed in sand and gravel, and all were between 47 and 100 feet deep, some variation exists in the concentrations of each of these chemical constituents. Just as well yields differ, water quality will vary depending on aquifer properties at the specific location of each well. One should not forget that many human activities also affect the quality of ground water.
| Table 1. Chemical constituents of selected Greene County wells. | ||||||
|---|---|---|---|---|---|---|
| Well No. | GR-1 | GR-10 | 1 | 2 | 3 | WQ Std1 |
| Well Depth (feet) | 77 | 100 | 47 | 80 | 74 | |
| Capacity (gpm) | 1,000 | 100 | 675 | 3 | 20 | |
| Depth to Bedrock (feet) | 107 | NE2 | NE | 55 | NE | |
| Water Bearing Formation3 | SG | SG | SG | SH | SG | |
| Chemical Constituents | ||||||
| Total Dissolved Solids4 | 465 | 513 | 544 | 412 | 458 | 500 |
| Hardness (as CaCO3) | 340 | 380 | 415 | 282 | 412 | None5 |
| Iron | 0.04 | 0.04 | 0.04 | 0.50 | 0.52 | 0.3 |
| Sulfate | 44 | 58 | 72 | -6 | - | 250 |
| 1 USEPA Secondary Water Quality Standard. | ||||||
| 2 Well constructed in this formation did not encounter bedrock. | ||||||
| 3 SG - Sand and Gravel; SH - Shale. | ||||||
| 4 Units are parts-per-million, ppm;
Comments as per Interpreting Your Water Test Report (1988); Total Dissolved Solids: Concentrations above 500 ppm may cause adverse taste and deteriorate domestic plumbing and appliances. Hardness: Primary concerns are that more soap is required for effective cleaning, a film may form on fixtures, fabrics may yellow and scales may form in boilers, water heaters and cooking utensils. Iron: Concentrations greater than 0.3 ppm may cause rust-colored stains on laundry, plumbing fixtures and sinks. Metallic taste may be present and may affect the taste of beverages made from the water. Sulfate: Concentrations in excess of 250 ppm may have laxative effect on persons unaccustomed to the water. Also affects the taste of water and will form a hard scale in boilers and heat exchangers. | ||||||
| 5 No USEPA Secondary Standard. | ||||||
| 6 Data not available. | ||||||
Greene County's ground-water resources are valuable assets to the county's citizens and industry. The availability and quality of these resources are directly influenced by the properties of the geologic formations underlying the county. By understanding the physical and chemical nature of these resources, better decisions can be made about ground water protection, management and use. This publication was designed to provide the reader with an overview of the county's ground-water resources. It should be used as a guide, and not as a substitute for detailed information and professional advice when drilling a well.
The Greene County Extension office can provide other publications about Greene County's water resources. Your Extension agent, the Greene County Department of Health, and the Ohio EPA Division of Drinking and Ground Water can provide information on well-water testing and drinking-water quality. The ODNR Division of Water - Ground-Water Resources Section (Fountain Square, Columbus, OH 43224) is an excellent source of information on ground water. Some of the information in this publication was summarized from the map, Ground-Water Resources of Greene County, and other information available through the Division of Water. This map is much more detailed than that given in Figure 1, and the Ground-Water Resources Section can provide detailed information on ground-water availability and wells. The USGS, Ohio District (975 W. Third Ave., Columbus, OH 43212), also provides information about ground water in Ohio.
Geologic Interpretation of Scenic Features in Ohio. 1972. J.E. Carman. ODNR Division of Geological Survey.
Greene County Water Resources. 1992. G.L. Mahan, K.M. Boone and L.C. Brown. AEX-480.29. Ohio Cooperative Extension Service, The Ohio State University.
Ground-Water Resources of Greene County. 1991. J.J. Schmidt. ODNR Division of Water. (map).
Ground-Water Resources of the Valley-train Deposits in the Fairborn Area (Greene County), Ohio. 1960. W.C. Walton and G.D. Scudder. Technical Report 3. ODNR Division of Water.
The Hydrogeochemistry and Hydrogeology of the Yellow Spring, Miami Township, Greene County, Ohio. 1991. M.J. Evers. Master of Science thesis. Wright State University.
Interpreting Your Water Test Report. 1988. D. Lundstrom and S. Fundingsland. AE-937, No. 13-AENG-10. North Dakota State University Extension Service.
Ohio Ground-Water Quality. USGS National Water Summary - Ohio. 1986. U.S. Geological Survey Water-Supply Paper 2325.
Ohio Ground-Water Resources. USGS National Water Summary - Ohio. 1984. U.S. Geological Survey Water-Supply Paper 2275.
Surface and Ground Water Terminology. 1990. L.C. Brown and L.P. Black. AEX-460. Ohio Cooperative Extension Service, The Ohio State University. Underground Water Resources (maps of various river basins). 1958-1962. ODNR Division of Water.
Water Inventory of the Little Miami River and Mill Creek Basins and Adjacent Ohio River Tributaries. 1964. Report 18. ODNR Division of Water.
The Water Resources of Greene County. 1950. Bulletin 19. ODNR Division of Water.
Water Testing. 1988. K. Mancl. AEX-314. Ohio Cooperative Extension Service, The Ohio State University.
This publication was produced through the Ohio Water Resources Education Project, in cooperation with: ODNR Division of Water; Ohio EPA; USGS, Ohio District; and Ohio Department of Health (ODH). Support for this publication was provided, in part, by: cooperating agencies; Greene County Extension office; Greene County Farm Bureau; Greene County Pork Producers Association; Greene Soil and Water Conservation District; Overholt Drainage Education and Research Program; and USDA Extension Service Grant No. 90-EWQI-1-9018. Project leaders are Larry C. Brown and Kristina M. Boone. The project leaders acknowledge the reviewers: Tom Ernstes (Greene Soil and Water Conservation District); David Cashell (ODNR Division of Water); Scott Golden (Environmental Health, ODH); Randall Reeder (Agricultural Engineering, OSU); Steve Hindall (USGS, Ohio District); and Rich Bendula (Ohio EPA Division of Drinking and Ground Water). A special thanks to Michelle Roby and Ross A. Roberts (Agricultural Engineering Undergraduate Assistants) for help in manuscript and graphics preparation, and Judy Kauffeld and Tonya Ewing (Section of Information & Applied Communications, OSU Extension) for editorial and graphic production.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868