Safe drinking water is vital to our communities, to our economy, and to our health. The best way to ensure a safe water supply, now and for the future, is to protect an area nearest the well from potential hazards.
This publication offers some guidelines for water
supply operators and wellhead protection planning teams who must hire a
qualified ground water scientist to delineate a wellhead protection area.
The area where the wells are located is called the wellhead area. The wellhead protection area includes much more than just the wells themselves. Delineation is the process of identifying how much of an area around those wells needs protecting.
The delineated area is important in that it serves
to focus the attention of the wellhead protection team on what activities
within that area might be potential contributors to groundwater pollution.
Potential is the important element here, in that Indiana’s Wellhead Protection
Rule emphasizes prevention rather than remediation. Once activities are
identified, the team can begin developing voluntary best management programs
and outreach efforts designed to educate those living and working within
the wellhead protection area on how they can all contribute to safeguarding
the water supply.
The rule says that if your water supply system currently
draws more than 100,000 gallons a day you need to delineate an area around
the wellhead that would protect your community’s groundwater for five years.
In other words, ground water directly underneath the boundaries of the
delineated wellhead protection area would require approximately five years
to travel to the pumping well (Figure 1). Systems that pump less than 100,000
gallons per day are not required to hire a consultant to perform a detailed
and scientific delineation. They have the option of delineating a 3000-foot
radius around the supply well as the wellhead protection area.
Figure1. A Wellhead Protection Area Showing a Five-Year Travel-Time Boundary
To determine the exact shape and size of the wellhead protection area, a qualified ground water scientist must be hired to collect information about the geology of the underground area through which the water flows, the volume of water that is pumped each day, predicted increases in water use, and other factors. The scientist enters the information into a computer program that simulates the way the water flows through the subsurface. Analytical models, semi-analytical models, or numerical models can be used for this simulation. The modeling method recommended by the consultant will depend on the size of the system, the complexity of the geology, and the intended type of management.
A five-year travel-time boundary will be determined
from the model. Inside this boundary is the delineated wellhead protection
area. This area is not usually in the shape of a circle. Because ground
water, like surface water, generally flows from a certain direction, the
area that needs protecting will extend farther in one direction than in
another. The delineated area may be more of a strip or an odd oval shape.
A modeled delineation is complex and according to Indiana's Wellhead Protection
Rule (327 IAC 8-4.1) must be completed by a "qualified ground water scientist."
But what exactly is a "qualified ground water scientist"?
A list of consultants is available on this Web site. These Consultants have self-registered and have listed the services they provide. This list is provided only as a service and does not imply endorsment or recommendation by Purdue Extension.
When you request a proposal, you should know exactly how much you are asking the consultant to do. Do you want only the approved delineation or a contaminant source inventory as well? Is the consultant going to set up a geographic information system (GIS) for you that can be updated periodically for a negotiated fee? Or will you receive only paper maps? Decide exactly what you need before you begin selecting a consultant.
Provide a list detailing what the deliverables will be to each potential consultant. Make sure each consultant addresses every item in the bid. Provide the phone number of a contact person who can answer questions about the proposal for the consultants. Attempt to choose from among three or more consultants who have submitted similar proposals for consideration.
The consultant may offer to do the entire wellhead protection plan for a fee. Beware of accepting this option. If the community does not document its involvement through the local planning team, the plan will be incomplete, and will not be approved by IDEM.
Delineations are complex and can require considerable
time and effort. A delineation may require from three weeks to three months
to complete. Get a clear estimate from the consultant on how much time
the delineation will require. Make sure the date agreed to by each of the
partners is stipulated in the contract.
You may not know if you need an analytical, semi-analytical, or numerical model for the delineation. The most complex model is the numerical model. The least complex is the analytical model. Generally, the model needed is dictated by the geology of the area, available data, and the management tools available to your community. If the geology is very complex, you need a more sophisticated model and more data to validate the model. If you plan to pass zoning ordinances, the model needs to be legally more defensible. You should question potential consultants about what model they recommend and why. If several consultants recommend the same type model for delineation, you will have more confidence in the recommendation.
A scientist who deals with ground water is a hydrogeologist or a hydrologist. A Professional Engineer (PE) or a Certified (or Licensed) Professional Geologist (CPG), may or may not be a hydrogeologist or a hydrologist.
When you hire a consulting firm, you are usually hiring one person, perhaps with the assistance of support personnel, who will ultimately provide the finished delineation.
Determine the qualifications of the individual you are hiring. A large firm may have a hydrogeologist on staff; however, a firm could also subcontract with another firm for the services of a hydrogeologist. The individual responsible for the delineation is the person to interview.
Educational and professional qualifications are the most important aspects to consider when hiring a consultant, but there are other considerations as well.
Below are some suggestions which may be helpful in choosing a consultant for your delineation.
Good consultants can clearly communicate the technical details of what they are trying to do. A knowledgeable consultant does not have to "snow" you and will appreciate having a well-informed client. Ask the consultant to describe in simple language how he or she will actually develop the delineation maps. If you can understand this explanation, it's a good indication that he or she will probably be able to explain the details of the delineation model as well.
Ask the potential candidates about contacting former clients. You should speak with some of the people who have previously used this consultant to find out whether the consultant can deliver what he or she promises. Consider asking former clients the following questions.
The contract should state that all or part of the payment will be made contingent on a delineation which is approved by the Indiana Department of Environmental Management. If the delineation is not approved, the contract should state that you are under no obligation to pay for the remaining charges. The contract should specify that regular meetings between the consultant and the contract monitor will be held to discuss the progress made on the delineation.
The consultant you hire will start you on the road to wellhead protection. After the Indiana Department of Environmental Management has approved your delineation, the wellhead protection planning team can complete the inventory of potential contaminants in the delineated wellhead protection area. The team can also begin working on formulating management and contingency plans, and developing a program for public education about wellhead protection.
The following Purdue Extension publications provide information about other aspects of the wellhead protection process:
2, "What is Groundwater?"
WQ 24, "Wellhead Protection in Indiana"
WQ-29, "Wellhead Protection Delineation: A Short Cut for Some Systems" (.pdf)
WQ-30, "Choosing A Consultant to Delineate the Wellhead Protection Area"
WQ-31, "Inventorying Potential Contaminant Sources" (.pdf)
To obtain these and other useful publications, contact your county Purdue Extension office or 1-888 EXT-INFO.
The USEPA has an excellent publication, "Wellhead Protection, A Guide for Small Communities," EPA/625/R-93/002 available free by calling 1-800-490-9198.