Stuart A. Smith and Allen E. Comeskey copyright 1998-2011, please copy but give credit to the authors and source, thanks.
Ground Water – Not "Out of Sight, Out of Mind" Anymore
Covered in this article:
- What is a hydrogeologic investigation?
- Who are these hydrogeologists anyway?
- How does an investigation help in decision-making?
- How do hydrogeologic investigations improve wellhead (source water) protection planning?
- Let the state to do it, or pay for it ourselves?
- How do we make the best use of our budget for hydrogeology?
The large majority of public water systems in Ohio and the USA (and all but a few of the small community systems, and almost all noncommunity public systems) are served by ground water, pumped by way of wells from formations that hold and transmit water, known as aquifers. For a water supply, ground water (or groundwater - preferred usage in the current fad) as a source water has several advantages over surface water when it is available in sufficient quantity: Even when it is not of the most desirable quality, ground water is a relatively drought-proof source, has relatively stable characteristics, and is relatively more protected from pathogenic microorganisms and synthetic chemicals.
Ohio has abundant and readily obtainable ground water except in some bedrock locations in southern counties and selected areas of far northwest and north-central Ohio away from valley aquifers. Even there, with improvements in technology, ground water can become a more accessible resource. Because of this water wealth, community and noncommunity systems in Ohio developed wells in a mostly unscientific fashion with few noticeable problems for many years and Ohioans have had the luxury of ignorance of their ground water resources. However, the terms "hydrogeologic study" and "hydrogeologist" have entered the vocabularies of water boards and managers all over the state as the Ohio EPA has attempted (at least in the past) to promote more scientific planning in siting wells and wellfields.
A hydrogeologic study or investigation is a study of the subsurface hydrologic and geologic conditions in an area or location. Data are collected about the type and thickness of geologic materials, the occurrence of ground water, how it flows in pore spaces and/or fractures, the quality of the ground water, and what can be expected at wells.
These studies are typically conducted by researching available published data from government and private sources and conducting the additional fieldwork needed to understand the location. The field work may consist of test drilling to log the geology, well construction and pumping tests to determine hydrologic performance, running geophysics to refine or confirm geologic information, and water sampling for water quality analyses. This work is most effective when conducted by hydrogeologists.
And who are these hydrogeologists, really? They are scientists or engineers with specific knowledge and experience in the occurrence and movement of ground water. Unlike many other states, Ohio, West Virginia, and Michigan have no formal licensing or registration of hydrogeologists, as there is for engineers. The Ohio EPA recognizes credentials, experience, and certification as qualifying factors. Hydrogeologists typically have a masters or Ph.D. degree (or a bachelors and years of experience), and may be certified by the National Ground Water Association, American Institute of Hydrology (AIH), or the American Institute for Professional Geologists (AIPG). Pictured right is Allen Comeskey, CPG (also licensed PG in Indiana and Pennsylvania). Ground Water Science's Stuart Smith, CGWP holds a license in Kentucky, where (unlike Ohio) they also care about geologist professionalism.
What does a professional hydrogeologist do besides add to the project cost? Professional hydrogeologists are experienced in specifying and supervising drilling and well tests, such as step tests for performance analysis and aquifer tests, and understanding how test behavior differs in various media, such as fractured rock and sand/gravel aquifers. Some tasks they perform:
- Aquifer testing and analysis: test drilling, siting new production wells, and site characterization
- Supervise and document production well and observation well construction
- Provide new public water supply well planning support (“OEPA” or “DEQ stuff”)
- Step-testing and analysis for performance and water quality testing for minimizing well interference and well field maximization
- Interpretation of down-hole camera surveys & borehole geophysical logging
- Specific ground water sampling
- Apply appropriate computer-based models to provide a moving view of the hydrogeologic setting.
(More explanation of procedures below.)
How will a hydrogeologic investigation help in public water supply decision making?
The investigation helps the public water supply manager to (in a more informed manner):
- Site new wells
- Manage well and total wellfield efficiency
- Track changes in well performance
- Properly delineate a wellhead (source water) protection area
- And generally provide information on the ground water source for long term planning.
The information yielded by a hydrogeologic investigation can aid a manager in obtaining the greatest efficiency from existing well fields and optimally siting new wells for long life. Changes in well performance can be documented and tracked to aid in well rehabilitation and replacement and the causes of declining production can be determined. Finally, the information aids in developing well head protection plans to safeguard public water supplies. In the near future, similar information will be needed for assessments under the U.S. Ground Water (Disinfection) Rule.
What do the different procedures do? A professionally conducted well performance test should provide you with valid information on expected future performance.
Step drawdown tests. With the right analysis, using short-duration step tests, you can document and benchmark well performance and determine where in the well system clogging is occurring. Monitoring changes in well performance over time provides the data needed by managers to determine the need for well rehabilitation or replacement.
Long term aquifer tests are used to determine aquifer characteristics. These data are used to plan well field expansions, estimate well interference and delineate well head protection areas.
Hydrologic modeling provides a simulation (now usually done in a computer) of how the ground water system in a region or location behaves. Modeling is one of the peripheral aspects that is most abused by nonhydrogeologists performing professional hydrogeologic services. The modeling approach chosen has to be appropriate for the hydrogeology of the location. Different models are capable of different kinds of simulations, and some are better than others.
Also critical is that the model provides an accurate-as-possible simulation of the local aquifer situation. A catch phrase of computer modeling is GIGO: "garbage in-garbage out." A hydrogeologist uses knowledge and experience in well performance, and with how water (and contaminants) move in different ways in various kinds of aquifers and non-aquifer formations, such as sands and gravel and fractured rock to filter out “garbage’ to make the model as realistic as possible.
So how do we use hydrogeologic testing in source water protection? A ground-water source water or wellhead protection area (WHPA) is defined as that land area through which contaminants may travel to reach the water well intakes. Usually, the WHPA (or groundwater SWAP) is based on the amount of time a contaminant may take to travel through the area to reach the water source, often 1 and 5 years, as specified in Ohio by the Ohio EPA. A hydrogeologic analysis (based on local factual data) is necessary to properly define the WHPA. The 1- and 5-year travel time areas are intended to allow a water supplier time to react to a problem should one occur. Within the WHPA, potential sources of contaminants are identified and managed to prevent contamination. Hydrogeologic analysis can determine whether a potential threat is likely to be real or not. Monitoring of ground water quality in the vicinity of the WHPA is regularly conducted to determine if a contaminant is migrating toward the water supply from an unknown source. The wellhead protection management and education plan (wellhead protection plan) is then developed to realistically manage this preventive process.
What are some practical approaches to wellhead protection delineation and planning?
There are several approaches to WHPA delineation and wellhead protection planning, ranging from "do nothing" (let the state do it or “hope for the best”) to complex, or from "penny-wise, pound-foolish" to "consultant full employment" at the other extreme. Neither extreme is recommended, of course.
One extreme: ‘Why should we pay for it? Let the state do it!’ Until recently, under the revised SWAP (source water assessment program), the Ohio EPA has conducted delineations at no direct cost to public water suppliers, and then provides information from databases on potential risks, and help to identify and assess the risk of these and others. Sounds good, but we're concerned about the quality of this "free" service, not because our colleagues at the OEPA are not capable (they have good and dedicated hydrogeologists and environmental professionals) but because of the size of the task in relation to the resources allocated to complete it, and the process (specifically, relying largely on existing hydrogeologic information). This "free" service has ended with the end of the federal money, so public water supplies are back to making their own arrangements.
Questions we suggest asking as you decide whether to budget a more thorough delineation or accept what you have been provided:
- OEPA delineations were accomplished using existing information. Is there enough? We have seen at least one where we know there is no valid local hydrogeologic data for a basis. Is it valid? Or is this a paper exercise?
- OEPA choice of delineation method is based on available information and not always the technical need. What does that mean for us?
- Do we just want a mapped delineation, or a "living" model that is a wellfield planning tool? Hydrogeologists working for you can adjust and manipulate the model to factor in "what ifs", either now or in the future. Ground Water Science provides the "living" version, also used to manage wellfield pumping to optimize well use.
- Who supports and updates your SWA 10 years from now? State investment in a task such as SWAP tends to wither when the program requirements are met, the budget dries up (like now), or when the spotlight turns somewhere else. Ground Water Science plans to support its product.
If you have to make the choices and don't have the funds to fund a delineation conducted by your own professional hydrogeologists (although villages as small as several hundred people have), invest in good collection of missing site-specific hydrogeologic data for your wellfield.
So, if a community decides to conduct its own professional SWA delineation, what do we suggest?
Over most of Ohio (and similar terrains throughout the Midwest), with relatively complex bedrock and valley aquifers, numerical hydrologic modeling using as much complete, accurate information as possible provides the most accurate possible WHPA delineation. This same model can also be used for future wellfield planning. So it has multiple uses. The model is a "living" planning tool that can easily be "tweaked" to try various "what-ifs" ("What if we put another 300-gpm well here?") and updated with new, improved information.
To be useful, it is important that WHPA and wellfield planning models be as representative as possible of the actual aquifer setting. This is best accomplished if hydrogeologists have good field-verified information on aquifer hydrology, geology (formation type, thickness, porosity), and structure (fracture patterns and anomalies in flow direction).
This information needs to be applied without preconceptions about "average" or "typical" values for an aquifer formation type, or what a delineation “should look like”. A "limestone" in a textbook may not bear much hydrologic resemblance to the "limestone" (actually dolomite) aquifer under a location in Mercer County, for example. And that location in Mercer County can be very different than one 40 miles away in Logan County (or even 5 miles – sometimes 500 yards – away). Rock structure data (overlooked in simplified delineations) can have a profound impact on a flow pattern on the scale of a WHPA.
While providing the most accurate simulation of geologic variables at the WHPA scale, a textbook criticism of numerical modeling in the past (still expressed at times) is that it was highly technical and time consuming, and thus relatively expensive. However, time marches on. With new computer technology and modeler experience, these costs have moderated for the same work (or much more analysis can be had for the same money).
Why go to all this effort to just obtain and display some information?
Here’s our question: What's avoiding wellfield problems worth to you? Experience shows that the cost of conducting a WHPA delineation, inventorying potential pollution sources, and implementing a management plan (if priced based on common professional rates and reasonable time expended) is always far less than the costs of emergency measures, such as developing an alternative water supply or adding treatment. Costs for professional performance of the entire WHPA delineation, inventory and planning process start at <$10,000 (spread over a period of years) for village-sized systems, or about $10,000 to $45,000 for a complicated WHPA delineation (in a Miami River Valley aquifer, for example). By contrast, air stripper units alone (used to remove VOCs), cost $300,000 to $750,000 just for the units, and pipelines exceed $50 per linear foot. Typical costs to deal with contaminated ground water for a small city in Ohio (PCE contaminating a sand-and-gravel aquifer) are going to start at $1 million.
Besides, new conditions and new potential risks pop up that require evaluation. So you still want "free" work from the state or Rural Water, or from grad students?
How can we make the best use of our budget for hydrogeologic studies?
Many hydrogeologists recommend that water suppliers "plan smart" -- for example, spending the "consultant" budget on tasks they cannot do well themselves (delineation) and recruiting staff and community resources for other tasks. This also increases community "ownership" of the process, important during implementation. With forward-looking time management, communities can make use of the considerable academic hydrogeologic resources in the state for delineation. Good planning saves money without compromising quality.
Monitoring and management plan development are the final areas where a professional hydrogeologist is particularly useful. Because a WHPA delineation model is just that, a simulation based (we hope) on the best available information, there is some uncertainty. Not all potential pollution risks may be identified (this is difficult). Monitoring ground water quality in the WHPA is an essential "early warning" indicator that something can be going wrong. Hydrogeologists can use their models and knowledge of geology to plan a cost-effective monitoring network.
In developing a management plan, hydrogeologists are often familiar with what does and does not work in other communities. Also, they will be familiar with education tools and resources in the ground water community. Here again, "planning smart" can result in good results for modest funding outlays: using high-priced professional time only just as necessary.
How do we make "doing it right" more affordable? There are ways to make technically valid, useful delineations affordable. First, State Revolving Fund money is supposed to be available under the 1996 SDWA amendments for just such circumstances. It should not be necessary to do second class work for small systems. Second, available data, used well by a hydrogeologist, can make a plausible delineation possible. A problem in Ohio is the spotty nature of detailed hydrogeologic information. The Ohio Department of Natural Resources' Division of Water ground water resource mapping function has been improving steadily with GIS mapping of a variety of data, but has a long way to go and currently is in a budget crunch.
A stepped up effort in aquifer mapping (beyond the current superficial effort) would be an excellent state investment in quality public water source protection. The contrast between what passes for available hydrogeologic information in Ohio and the detail of some other, much-less-populous, states such as North Dakota, is startling and should be embarrassing to top State of Ohio officials involved in water supply financial and technical decision-making. The actual total cost would be relatively modest by government standards (and perhaps U.S.EPA fundable under evolving Source Water Protection efforts).
We have an additional valuable resource in the state in the form of the numerous university hydrogeology programs and their students (see our links page for some contact points as well as numerous other information sources). Students (especially at the graduate level) have been valuable in performing additional technical analysis and time-intensive modeling. Employed and supervised well by professional hydrogeologists, they can add greatly to a valid delineation and understanding of a community's ground water resources.
Hydrogeologists in Ohio: The "Undiscovered Country" as a professional resource for public water supply.
Professional hydrogeologists living and practicing in Ohio provide a full range of hydrogeologic services and investigations. State-of-the-art investigative methods and computers to study and analyze your local hydrogeology are available from a variety of sources. The principals and lead staff hydrogeologists in a number of Ohio's ground water consulting firms have many years of pump testing, drilling, sampling, aquifer characterization and modeling experience. You don't need to hire some expensive out-of-state firm – or even a big firm in Ohio – to get quality work. In fact, the quality is right here -- so buy Ohio. In fact, no firms in Ohio (or adjacent states) will offer a better service than Ground Water Science.
Perhaps most of all: You don't have to dig deep into an Ohio hydrogeologist such as Ground Water Science's Stuart Smith, CGWP, and Allen Comeskey, CPG to find a definite love of ground water science that goes beyond billable hours and product. It is the kind of love of the work that experienced water system operators recognize in their own community of professionals. A professional hydrogeologist, through dedication to the process and his or her own professionalism, will work with the water system manager to do the job right with the resources available.