Wellhead Protection Programs Research Articles

Biofilms Controlling in Industrial Cooling Water Systems: A Mini-Review of Strategies and Best Practices.

Biofilm formation and growth is a significant concern for water treatment professionals, as it can lead to the contamination of water systems and pose a threat to public health. Biofilms are complex communities of microorganisms that adhere to surfaces and are embedded in an extracellular matrix of polysaccharides and proteins. They are notoriously difficult to control, as they provide a protective environment for bacteria, viruses, and other harmful organisms to grow and proliferate. This review article highlights some of the factors that favor biofilm growth, as well as various strategies for controlling biofilm in water systems. Adopting the best available technologies, such as wellhead protection programs, proper industrial cooling water system maintenance, and filtration and disinfection, can prevent the formation and growth of biofilms in water systems. A comprehensive and multifaceted approach to biofilm control can reduce the occurrence of biofilms and ensure the delivery of high-quality water to the industrial process.

Addressing Italy’s urban flooding problems through the holistic watershed approach by using blue/green infrastructure

Water resources have been neglected and stressed for many years, as anthropogenic changes in watersheds have increased runoff, decreased infiltration and aquifer recharge, caused stream incision and streambank erosion and degraded water quality and water resources. The watershed is the management unit to begin to solve stormwater problems and flooding issues. Reversing the mismanagement from the past is a complicated process and must consider a holistic approach factoring in all the processes that cause the aforementioned problems. There are many technological tools such as GIS and hydrologic, hydraulic and water quality models that help pinpoint the sources of problems in the watershed and help derive at a comprehensive solution. The objective of this paper is to provide researchers and practitioners a systematic, methodical and proven approach to documenting and solving water management issues cause by unmanaged anthropogenic changes that have occurred in rural and urban watersheds. There are many regulations and literature about flooding and watershed plans with very detailed guidelines composed by state authorities, however, there are few that completely address the comprehensive, inclusive approach to watershed management to solve a variety of problems. For example, the State of Pennsylvania, USA has separate flood plain management, stormwater management, erosion and sediment pollution control and nonpoint discharge and elimination system (NPDES), and water supply / wellhead protection programs and regulations as opposed to one single “water resources management” regulatory program. This paper defines an innovative approach to overcome some of the restrictions placed on engineers and planners by regulatory programs.

Numerical modeling on flow of groundwater energies in transient well capture zones

Capture zone delineation is indispensable in all wellhead protection programs for the safeguarding of groundwater supplies. Transients in the flow model tend to influence the capture zone geometry over time. Thus, transient analyses of well capture zones are superior to the steady-state analogs for all practical cases with time-varying flow parameters. Energy gradients drive groundwater flow like any other natural phenomena. Along with the evolving capture zone, energy transformations within the model domain were also, therefore, assessed to portray the state of the system with time. The energy components, in the form of frictional dissipation and change in internal energy, were estimated at all time steps beside delineating the capture zones. This paper numerically models a two-dimensional homogeneous isotropic confined aquifer and thereby delineating the capture zones by subsequent examination of the energies within. The energy approach facilitated the identification of areas having pronounced transient behavior compared to the entire region within the capture zone and model domain. The current study reveals that there was an unusual increase in the internal energy term for two time periods of the entire cycle investigated and highlighted the compressibility effects of the system. This has been correlated to the change in the distribution of capture fraction values within the capture zones of those specific time periods.

Capture Zone of a Partially Penetrating Well with Skin Effects in Confined Aquifers

The analysis of the capture zone of wells is useful to design pumping systems and wellhead protection programs. In this study, an analytical solution for the head distribution of a partially penetrating well, and semi-analytical methods to determine the geometry of the capture surface are presented. The analytical solution is derived based on an infinitesimal radius under a constant pumping rate in a two-zone confined aquifer. Using the developed solution, a sensitivity analysis is performed to study the influence of skin on the drawdown, location of the stagnation point, maximum horizontal and vertical extent of the capture surface. The results show the efficiency of a partially penetrating well in the plume removal process is different for positive and negative skins. Also it can be concluded, the skin effect will decrease as the degree of penetration and pumping discharge of the well increase. Generally, the thickness of the skin zone is an influential factor in well hydraulics and hydraulic head distribution. However, it can be seen where the skin zone is less than some specific values, the skin effect is not a significant factor, thus, the geometry of the capture surface can be obtained by assuming a single-zone aquifer. Moreover, the effects of different parameters (pumping rates, degree of penetration of the well, thickness of the skin zone, etc.) on the capture zone are studied.

What Can We Learn From Exemplary Groundwater Protection Programs?

Source water protection is receiving considerable attention due to contamination concerns related to drinking water. While this important issue has intensified over the past decade, several municipalities in Canada and the United Stated have considerable experience with practicing groundwater protection. This research investigates wellhead protection programs in the Region of Waterloo (Ontario) and the City of Dayton (Ohio). The context and process of developing these exemplary municipal groundwater protection programs are described. Cross-case analysis compares the cases in terms of the development process, employment of regulatory and non-regulatory tools, points of innovation, and challenges confronted. Experiences from these cases confirms the need for an appropriate mix of tools for groundwater protection, the importance of organizational capacity and the need for supportive and flexible institutional arrangements. Suggestions are offered for municipalities undertaking groundwater protection programs.

Integration of Watershed Planning and Wellhead Protection Programs

Integration of Watershed Planning and Wellhead Protection Programs

Sensitivity and uncertainty analysis of the recharge boundary condition

The reliability analysis method is integrated with MODFLOW to study the impact of recharge on the groundwater flow system at a study area in New Jersey. The performance function is formulated in terms of head or flow rate at a pumping well, while the recharge sensitivity vector is computed efficiently by implementing the adjoint method in MODFLOW. The developed methodology not only quantifies the reliability of head at the well in terms of uncertainties in the recharge boundary condition, but it also delineates areas of recharge that have the highest impact on the head and flow rate at the well. The results clearly identify the most important land use areas that should be protected in order to maintain the head and hence production at the pumping well. These areas extend far beyond the steady state well capture zone used for land use planning and management within traditional wellhead protection programs.

The geochemistry and mixing of leakage in a semi-confined aquifer at a municipal well field, Memphis, Tennessee, USA

The Memphis aquifer in southwestern Tennessee is confined to a semi-confined unconsolidated sand aquifer and is the primary municipal water source in the Memphis metropolitan area. Past studies have identified regions in the metropolitan area in which the overlying upper Claiborne confining unit lacks significant clay and provides a hydraulic connection between the shallow aquifer and the Memphis aquifer. In this study, major solute chemistry, 3H, and 3H/ 3He groundwater dating are used to investigate the extent and chemical effects of leakage through the confining unit to the Memphis aquifer in the vicinity of a municipal well field. The 3H/ 3He dates and geochemical modeling of the chemical data are used to constrain mixing fractions and the timing of modern recharge. Tritium activities of as much as 2.8 TU are observed in shallow production wells, but deeper production wells have 3H activities that approach the detection limit. Trends in water chemistry indicate vertical mixing in the aquifer of shallow Na–SO 4–Cl-rich water and deeper Ca–Mg–HCO 3-rich water. Water chemistry does not vary consistently with seasonal pumping, but 3H activity generally decreases during low use periods. Stable O and H isotopes show little variation and are not useful groundwater tracers for this study. The 3H-bearing, Na–SO 4–Cl-rich water is interpreted to reflect recharge of modern water through the upper Claiborne confining unit. The 3H/ 3He dates from 5 production wells indicate modern recharge, that infiltrated 15–20 a ago, is present in the shallow production wells. Geologic data and hydrologic boundary conditions suggest that the most likely source for continued leakage is a nearby stream, Nonconnah Creek. Geochemical reaction modeling using the NETPATH computer code suggests that proportions of shallow aquifer water leaking into the Memphis aquifer range from 6 to 32%. The 3H/ 3He dating and NETPATH modeling results correlate well, suggesting that these complementary analytical tools provide an effective means to evaluate proportions of modern water leaking into semi-confined aquifers. These results also indicate a need to carefully consider connections between surface water and semi-confined groundwater resources in wellhead protection programs.

Comparison of Models for Delineating Wellhead Protection Areas in Confined to Semiconfined Aquifers in Alluvial Basins

AbstractThe 1986 Safe Drinking Water Act Amendments include provisions for state wellhead protection (WHP) programs that address wellhead protection areas (WHPAs). In many states, WHPAs are delineated based on time‐of‐travel (TOT) criteria. This study compares 250‐day and 15‐year TOT capture zones computed in a confined to semiconfined aquifer system in an alluvial basin using semianalytical and two‐ and three‐dimensional numerical ground‐water flow models, and evaluates the relative importance of several sources of uncertainty, such as aquifer hydraulic conductivity, aquitard leakance, vertical transit time, hydraulic gradients, transient pumping effects, well interference, and three‐dimensional aquifer geometries.A numerical model should be used to delineate 15‐year TOT capture zones for wells in confined to semiconfined aquifers in alluvial basins. A semianalytical program may be acceptable for computing the 250‐day TOT capture zones; however, such codes can be applied only under a very narrow range of conditions.Hydraulic conductivity plays a critical role in controlling the sizes and shapes of capture zones computed in confined to semiconfined aquifers. Small, circular capture zones are computed in low hydraulic conductivity areas. More complex geometries should be expected where hydraulic conductivities are higher and pumping wells are in close proximity to each other. Aquifers with horizontal hydraulic conductivities that are greater than 1,000 times the vertical hydraulic conductivity of the overlying aquitard are effectively fully confined, and larger capture zones would be computed for these aquifers than for semiconfined aquifers where significant leakage is induced by pumping. In addition, relatively large drawdowns are computed in low hydraulic conductivity areas, resulting in short vertical transit times. Vertical transit times are longer where aquifer hydraulic conductivities are higher.

A Summary of State Wellhead Protection Programs

Groundwater Monitoring & RemediationVolume 17, Issue 2 p. 61-63 A Summary of State Wellhead Protection Programs Charles Job, Charles Job This column was prepared by Charles Job, with the assistance of Philip Berger, Harriet Colbert, James Hamilton, of the U.S. EPA Office of Ground Water and Drinking Water, M St., S.W., Washington, DC 20460.Search for more papers by this author Charles Job, Charles Job This column was prepared by Charles Job, with the assistance of Philip Berger, Harriet Colbert, James Hamilton, of the U.S. EPA Office of Ground Water and Drinking Water, M St., S.W., Washington, DC 20460.Search for more papers by this author First published: 22 February 2007 https://doi.org/10.1111/j.1745-6592.1997.tb00155.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume17, Issue2May 1997Pages 61-63 RelatedInformation

Comparative Analyses of Local Wellhead Protection Programs

Comparative Analyses of Local Wellhead Protection Programs

Sources of Water to Wells for Transient Cyclic Systems

AbstractMany state agencies are currently (1995) developing wellhead protection programs. The thrust of some of these programs is to protect water supplies by determining the areas contributing recharge to water‐supply wells and by specifying regulations to minimize the opportunity for contamination of the recharge water by activities at the land surface. The area contributing recharge to a discharging well is the surface area at the water table through which the water flowing to the well entered the ground‐water system. In the analyses of ground‐water flow systems, steady‐state average conditions are commonly used to simplify the problem and make a solution tractable. However, recharge is usually cyclic in nature, with seasonal cycles and longer term climatic cycles. The effect of these cyclic stresses on the area contributing recharge to wells is quantitatively analyzed for a hypothetical alluvial valley aquifer system that is representative of a large class of ground‐water systems that are extensively developed for water supply. The analysis shows that, in many cases, these cyclic changes in the recharge rates do not significantly affect the location and size of the areas contributing recharge to wells. The ratio of the mean travel time to the length of the cyclic stress period appears to be an indicator of whether the transient effects of the cyclic stress must be explicitly represented in the analysis of contributing areas to wells. For the cases examined, if the ratio of the mean travel time to the period of the cyclic stress was much greater than one, then the transient area contributing recharge to wells was similar to the area calculated using an average steady‐state condition. However, cyclic stresses on systems with ratios less than one do have an effect on the location and size of the areas contributing recharge to wells.

The Role of Geology in Wellhead Protection Programs: Case Studies from the Coastal Plain of Eastern Alabama: ABSTRACT

ABSTRACT Programs that protect ground-water supplies from potential contamination and which identify and define alternate sources of ground water are known as Wellhead Protection Programs. An important requirement in developing a viable program is a thorough understanding of an area's geology. Since the coastal plain of eastern Alabama is structurally uncomplicated, the occurrence of ground water, its direction and rate of flow, its production potential, and to some extent its quality, is primarily controlled by the stratigraphy and lithologic properties of the sediments. Geological assessments conducted for wellhead protection programs in southeastern Alabama have led to some unsuspected results. In some areas, high topographic relief results in the nearby surface exposure of otherwise moderately to deeply buried aquifers. The high susceptibility of these aquifers to nearby surface contamination is critical in developing effective wellhead protection programs. Of even greater concern is disorder in the shallow subsurface stratigraphy resulting from inadequate drillers' descriptions of penetrated lithologies, the nonrecognition of facies change along strike and dip, and the lack of regional paleoenvironmental interpretations. This has led to the misidentification of aquifer and confining units resulting in confusion in the definition, delineation, and correlation of hydrologic and geologic data. Case examples from southeastern Alabama demonstrate how detailed sedimentological analysis and local and regional interpretation of stratigraphy is essential in the preparation of effective wellhead protection programs and in the identification of alternate sources of ground water.

Radiocarbon and δ13C Values Related to Ground‐Water Recharge and Mixing

AbstractGround‐water levels in the Upper Floridan aquifer beneath the southeastern coast of South Carolina have undergone pumpage‐induced declines approaching 20 ft below sea level at the southern end of Hilton Head Island. This scenario suggests the potential exists for the inducement of recharge to the Upper Floridan aquifer across the island, which could affect the quality of water being pumped by wells. However, low radiocarbon concentrations in ground‐water samples (0.5 to 1.4 ± 0.1 PMC) indicate that most of the water is relict ground water reflecting prepumpage ground‐water flow conditions in the Upper Floridan aquifer. The isotopic data indicate long residence times and water‐chemistry evolution more characteristic of ground‐water recharge occurring farther inland prior to the commencement of pumpage in the late 1800s.Radiocarbon concentrations (as Percent Modern Carbon) and stable carbon isotope ratios (as δ13C in dissolved inorganic carbon) determined during this study and reported in other studies on and around Hilton Head Island varied in a systematic manner. Heavier δ13C values (–2.8 to –1.6 per mil) in ground water beneath southern Hilton Head Island reflect ground‐water discharge from prepumpage flowpaths originating over 100 miles away, hence a depletion in radiocarbon concentration with corrected ground‐water ages no younger than 16,000 yrs BP. In contrast, lighter δ13C values (–13.9 to –8.67 per mil) beneath the northern part of the island indicate recent recharge as a result of water‐level declines, and recharge in areas off the island that have not changed as a result of pumpage (evidenced by enrichment in radiocarbon with corrected ground‐water ages no older than 4,000 yrs BP). This suggests that the δ13C composition of ground water in the Upper Floridan aquifer is a useful indicator of mixing between ground waters from different sources, and can be used to delineate recharge‐discharge patterns. This approach may be applicable to other aquifers of highly evolved ground‐water chemistry in regional carbonate aquifer systems that may be receiving recent recharge. Moreover, this approach could prove useful in delineating the contribution of recent water being captured by pumped wells as part of wellhead protection programs designed to assess aquifer vulnerability from surficial contaminant sources.

Analytical Model for Estimation of Steady‐State Capture Zones of Pumping Wells in Confined and Unconfined Aquifers

AbstractThe analysis of capture zones of pumping wells is useful for designing pumping systems and wellhead protection programs. Using discharge potentials, equations are derived that can be applied to confined, unconfined, or combined confined and unconfined aquifers. The transient equations are transcendental and cannot be solved explicitly. However, infinite‐time (steady‐state) equations are presented which can be solved. They define an area in which, theoretically, all the water in the aquifer will eventually reach the pumping well, although the equations do not consider the effects of hydrodynamic dispersion. Equations for calculating the stagnation point, upgradient divide, and dividing streamline within the aquifer and an example problem are presented.

SDWA Amendments: Effects on the Water Industiy

Water utilities throughout the United States will be affected by the 1986 amendments to the Safe Drinking Water Act. The authors describe these effects along with suggesting preparations that can be undertaken to meet the requirements of the new law when it is fully implemented. Water utilities must deal with new contaminant standards, including installation of new treatment technologies that may be needed to meet these new standards. Wellhead protection programs and required disinfection of groundwater and surface water supplies will change the way in which many systems now operate. The far‐reaching effects of more stringent regulation of the by‐products of disinfection, coupled with disinfection adequate to contend with viruses and Giardia, will cause an exquisite balancing of potentially conflicting goals in water treatment.