e GA- e f\!~oo.G,4 I 51 1'7 . e no. aiL\ I ASSESSME~T OF ENVI~ONMENTAL EFFECTS ASSOCIAifED WITH POTENTIAL AQUIFER STORAGE RECOVERY PROJECTS IN COASTAL GEORGIA DEPARTMENT OF NATURAL RESOURCES I ENVIRONMENTAL PROTECTION DIVISION I GEORGIA GEOLOGIC SURVEY I I I Atlanta 2001 PROJECT REPORT 44 ASSESSMEfjjT. OF ENVIRONMENTAL EFFECTS ASSOCIAifED WITH POTENTIAL AQUIFER STORAGE RECOVERY PROJECTS IN COASTAL GEORGIA Performed as parte' the Georgia Environmental Protection Division's . Interim Strategy t0 protect coastal Georgia from salt-water intrusion DEPARTMENT OF NATURAL RESOURCES I Lonice C. Barrett, Commissioner . I . ENVIRONMENTAL PROTECTION DIVISION Harold F. Reheis, Director . f3EORGIA GEOLOGIC SURVEY William H. Mclemore, State Geologist Atlanta 2001 PROJECT REPORT 44 Reply To: Georgia Geologic Survey Room 400 19 Martin Luther King, Jr. Di. S.W . Atlanta, Georgia 30334 (404) 656-3214 Georgia Department of Natural Resources 205 Butler Street, S.E., East Floyd Tower, Atlanta, Georgia 30334 Lonice C. Barrett , Commissioner Harold F. Reheis, Director Environmental Protection Division (404) 656-4713 June 1, 2001 : To: Coastal Georgia Ground Water Stakeholders From: William H. MJemoreb<---- State Geologist Subject: Project Report 44; ASSESSMENT OF ENVIRONMENTAL EFFECTS I ASSOCIATED WITH POTENTIAL AQUIFER STORAGE RECOVERY ' I PROJECTS IN COASTAL GEORGIA This Project Report cohrains two separate reports (Appendices 1 and 2) dealing with the environmental impacts!that might be associated with aquifer storage and recovery (ASR) projects in coastal Georgia.. In this regard, two separate contractors were given the following identical mi~sion to assess the published and unpublished technical literature regarding the following issues, which have been raised by coastal Georgia stakeholders (i.e., identified as part! of a facilitated meeting sponsored by the Georgia Conservancy under contract to EPD and included in this Project Report as Appendix 3): "What happenl during aquifer storage and recovery (ASR)? That is, what happens to m4vement of stored water, quality of stored water and quality of natural water under ASR? What are the effects locally? What is the localized I movement? What are the effects across the full sphere of influence? How far does the spheri of influence extend? Others include: --effects bf mixing aerobic and anaerobic waters; -geochJmical effects on the aquifer itself(on the limestone formations); -effects lofprior treatment; and -mixing effects in general. In addition to the above, EPD requested the two contractors to also consider: . P~tentibz (1) for the introduction of regulated or radioactive (i.e., tritium) chemicals intd the subsurface, and in the event that such chemicals were introduc~d, thJ viability of successfully removing such chemicals and preventing them from bein1g introduced into a public drinking water system. : I (2) Potential impact upon wells belonging to other persons (i.e., loss of water) . (3) Other negative impacts. " The assessment of the above issues, which did not indude any field studies or measurements, w~s to bb summarized in a short report that would generally discuss actual and. perceived adv,erse JInvironmental impacts. Any actual environmental im.pacts would be documented and properly cited . The above work was lontracted to the firms of CH2MHill. (Appendix 1) and Golder I . Associates (Appendix 2). Both CH2MHill's and Golder's reports were peer reviewed by LAW Environmental ahd Engineering, Inc. and Camp Dresser and McKee, Inc. LAW and Camp Dresser ancl McKee were further requested to render a technical opinion regarding: Are the~e any inherent adverse environmental impacts associated with ASR in coastal Georgia that could not be mitigated by competent and reasonable engineering de~ign and thus would preclude the siting and construction of such a facility . Before proceeding further, it is important to remember that ASR is regulated as part of Underground Injection/ Control (UIC), which_ is a federally delegated program from the United States Environmental Protection Agency (EPA). The legal authority under which UIC rules are promulgited is the Georgia Water Quality Control Act (O.C.G.A. 12-5-20). In the spring of2001) Georgia's UIC rules were revised to achieve consistency with changes in EPA regul~tions. The revised rules, which became effective on April 26, 2001 are provided in .Aippendix 4. Georgia's UIC ll!les p1ovide: No person shaH operate an ASR in a manner that allows the movement of fluid containing any/ contaminant into any aquifer, if the presence of the contaminant may caus~ a vi0lation of drinking water standard. ~SR Injected later shall be sited so that both the aquifer and nearby wells are not . contaminated./ [Note: Georgia's Ground-Water Management Plan further provides that such a siting study shall only be done by a Georgia P.E. or P.O.] pro~ulgated Injected ASR Later shall not contain. any. contaminate that exceeds. drinking : watet standard (i.e., the injected water must meet drinking water standards) . ASR shall not proceed without the owner first obtaining a permit from EPD; and the permit mal contain provisions for monitoring, testing, and reporting. Both CH2MHili and lll 0 ~ <>D 0 0 a l..l..l 0 -e..n.. z " C'i ;; Cl) 0 ...' e:In 0 '0:::/ u:: ~ ., APPENDIX2 ,. ,. .I Golder Associates Inc. 3730 Chamblee Tucker Road Atlanta. GA USA 30341 Telephone (770) 496-1893 Fax(770)934-9476 TRANSMITTAL LETTER TO: Georgia Geologic Survey 19 Martin Luther King Jr. Drive SW Room 400 Atlanta, Georgia 30334 ATTN: Dr. William McLemone DATE: April27, 2001 Project No.:003-3019.002 State Geologist Sent by: Jim Renner OMail D Air Freight D Hand Carried QUANTITY 3 ITEM Reports D Under Separate Cover D Enclosed [8J Federal Express DESCRIPTION Report on Environmental Review of Aquifer Storage and Recovery in the Floridian Aquifer of Coastal Georgia 1 Remarks: Per: OFFICES IN AUSTRALIA. CANADA. GERMANY. HUNGARY. ITALY, SWEDEN. UNITED KINGDOM. UNITED STATES \. Golder ASsociates Inc. 3730 Chamblee Tucker Road Atlanta. GA USA 30341 Telephone (770) 496-1893 Fax (770) 934-9476 REPORT ON. ENVIRONJ\.1ENTAL REVIEW OF AQUIFER STORAGE AND RECOVERY IN THE FLORIDAN AQUIFER OF COASTAL GEORGIA Submitted to: Georgia Geologic Survey 19 MartinLuther King Jr. Drive SW Room 400 Atla1;1ta, Georgia 30334 Prepared by: Golder Associates Inc. 3730 Chamblee Tucker Road .Atlanta, GA 30341 Distribution: 3 Copies - Georgia Geologic Survey 9 Copies -Golder Associates Inc. April2001 003-3019.002 OFFICES IN AUSTRALIA. CANADA. GERMANY. HUNGARY. ITALY. SWEDEN, UNITED KINGDOM, UNITED STATES ,. Georgia Geologic Survey Dr. William McLemore - 1- TABLE OF CONTENTS April2001 003-3019.002 Table of Contents .............................................................................................................................. i Exe~utive Summary ................................................................. ~................................................... E-1 SECTION PAGE J.,Q INTRODUCTION .......................................:........................................................................ 1 Ll Background ........................................................................................................................ 1 !.1 Report Objective and Approach ........................................................................................ 2 2.0 ASR PHYSICAL AND HYDROCHEMICAL PROCESSES ..............................................4 D Physical Processes ............................................................................................................. 4 2.2 Water Quality Processes .................................................................................................... 5 . 3:0 IMPACTS AND IMPACT MITIGATION- LOWER FLORIDAN AQUIFER .................. 7 lJ. Physical Effects ................................................................................................................. 7 3.2 Water Quality Effects ........................................................................................................ 7 3.2.1 Suspended Sediment Fonnation ................................................................................. 7 3.2.2 Disinfection By-products ........................................................................................... 8 3.2.3 Solute Transport Effects ............................................................,................................ 9 4.0 IMPACTS AND IMPACT MITIGATION- UPPER FLORIDAN AQUIFER.................. tO 11. Physical Effects ................................................................................................................ 10 4.2 Water Quality Effects ...................................................................................................... 11 4.2.1 Suspended Sediment and Disinfection By-products ................................................ 11 4.2.2 Uranium Mobilization and Introduction of Tritium ................................................. 11 4.2.3 Pyrite Oxidation .......................................................................:............................... 12 4.2.4 Advective Transport ................................................................................................. 12 4.2.5 Diffusion Exchange ofSolutes..........................................................:...................... 13 5.0 SUMMARY ....:......... ~.; .............................................................................,......................... 14 In Order Following Page 13 TABLES TABLE 1 TABLE 2 Potential Impacts Associated with ASR Operations in the Lower Floridian Aquifer Potential Impacts Associated with ASR Operations in the Upper Floridian Aquifer FIGURES FIGURE 1 Conceptual ASR Operation APPENDICES APPENDIX A Summary of Documented Environmental Impacts of ASR Operation APPENDIX B Floridan Aquifer Hydrogeology APPENDIX C Bibliography Golder Associates Georgia Geologic Survey Dr. William McLemore - E-1 '- April2001 003-3019.002 EXECUTIVE SUMMARY The Georgia Environmental Protection Division Geologic Survey Branch (GAEPD) requested that Golder Associates Inc. identify environmental impacts tha.t might arise from construction and operation of an aquifer storage and recovery (ASR) system in the Floridan Aquifer of coastal Georgia. This review .included an examination of the following issues identified by GAEPD as being of significance to coastal Georgia stakeholders: Movement and distribution of water recharged to the aquifer; Pressure. effects resulting from injection, including ground stability or water level impacts on wells adjacent to the ASR well field; Alteration of the quality of the water recharged to the aquifer (including the likely effects of chemical reaction between the recharged water and the Floridan Aquifer limestones); Alteration of the quality of any in situ groundwater affected by ASR operations (including general mixing effects and the effect of mixing aerobic and anaerobic water); Potential for the introduction of regulated or radioactive substances (e.g. tritium) ~o the Floridan Aquifer; and Likelihood that contamination can be successfully remediated. Golder Associates performed a limited review and assessment of the published and unpublished technical literature on ASR and considered the physical and hydrochemical processes of ASR in light of the characteristics of the Upper and Lower Floridan Aquifers. No instances where aquifers have become polluted as a consequence of ASR have been reported by EPA. In addition, no literature was reviewed that identified physical impacts resulting from an operating ASR. However, physical and hydrochemical processes of ASR could result in environm~ntal impacts depending on the design and operation of a specific ASR system, the characteristics of the storage aquifer and confining or interconnected units, and the utilization of other production wells. Potential impacts of ASR in the Floridan Aquifer of coastal Georgia might include: Lower Floridan Aquifer . Generation of suspended iron and manganese oxi-hydroxide sediment due to dissolved oxygen in the injected water; ~ Generation of Disinfection by Products (DBP's) as a consequence of organic matter oxidation by disinfection chemicals present in the injected water; Increased solute concentrations in the Upper Floridan Aquifer as a consequence of the ASR-induced displacement of poor quality water from the Lower Floridan. Golder Associates Georgia Geologic Survey Dr. William McLemore - E-2- April2001 003-3019.002 Upper Floridan Aquifer Uncontrolled discharge from improperly abandoned wells, loss of yield in nearby production wells, and ground destabilization effects linked to water level changes during injection and recovery; . Suspended sediment and DBP generation similar to that described for the Lower Floridan Aquifer; Increased concentration of dissolved uranium due to oxidation of uranium-bearing minerals by dissolved oxygen in the injected water; Increased sulfate and metal concentrations and decreased pH as a consequence of pyrite oxidation in the Upper Confining Unit due to ASR-induced dewatering of the unit; Lateral migration of poor quality water to other production wells due to flow in large diameter conduits in the southern coastal area and steep hydraulic gradients. in the northern coastal area; Diffusion of exchange of solutes between the injected water and the aquifer matrix. In each case, the probability of the impact being realized, the severity of the impact, and the need for and design of impact mitigation measures could be ass.essed by site-specific investigations for a proposed ASR. Such investigations would: Describe the local geology, hydrogeology, and hydrochemistry; Model the behavior of the aquifer and associated units during alternative injection and recovery scenarios; Define source-pathway-receptor relationships (e.g. the influence of the proposed ASR on other production wells or sensitive hydrologic systems). Following the initial assessment, pilot testing would be an effective means of validating models, making direct observations of physical and hydrochemical pr?cesses, and comparing alternative ASR designs and operating schedules. Finally, monitoring water quality, aquifer characteristics, and ground conditions in potentially sensitive areas during ASR operation would alert operators to possible concerns. Such a monitoring program implies effective facility maintenance, staffing, and operator training as a necessary requirement of ASR operation. In summary, ASR has the potential to be a useful water resource management tool in coastal Georgia. ~orne concerns have been identified, but no environmental impacts have been identified that could not potentially be mitigated. An active permit program administered by GAEPD could insure that pre-construction investigations, pilot testing, and ASR design, operation, and monitoring are adequate to achieve the water resource management benefits while mitigating environmental impacts. Golder Associates Georgia Geologic Survey Dr. William McLemore - 1- April2001 003-3019.002 1.0 INTRODUCTION 1.1 Background Aquifer storage and recovery (ASR) is a water resources management technique in which treated water is stored by injection into permeable geologic formations. Common ASR applications include: Meeting demand during periods when the available reserves of raw water are depleted (during droughts, .for example); Meeting demands which exceed the available treatment capacity (peak demand. management); Managing groundwater levels for the purpose of maintaining well-field yields or t: controlling salt-water intrusion. During typical ASR operations, treated water from a surface source or supply aquifer is injected into an alternate aquifer when surplus water resources are available, demand is low, and surplus treatment capacity exists (Figure 1). The duration of the subsequent storage period is usually a I function of seasonal influences on resource availability and demand. A combination of demand, . available yield and the total volume of treated water in storage determine the rate and duration of recovery . Operational ASR facilities are found in Europe, Africa, Australia and the United States. Systems . in the United States have been in operation or in pilot studies for about thirty years, including approximately 34 facilities in Florida, several of which utilize the Floridan Aquifer. Typically; these facilities utilize either treated surface water or treated ground water as their supply source. However, Florida has recently issued two construction permits, received another construction application and held two pre-application meetings with several utilities interested in using reclaimed wastewater as an ASR source water. Raw ground water injection and raw surface water injection are also proposed (ASRIT, 1999). In South Carolina, three ASR systems are operating and one system has been under study for 6 . years (Campbell, 2000): The Beaufort-Jasper Water and Sewer Authority injects treated Savannah River water into the Upper Floridan Aquifer to supply peak demands during summer months, thereby avoiding the need to build an additional treatment plant. The ASR system has operated for one year. Last year 140 million gallons were injected and120 million gallons were Golder Associates .) Georgia Geologic Survey Dr. William McLemore -2- April2001 003-3019.002 withdrawn at a rate of about 2.5 mgd. The withdrawn water is treated lightly (slight disinfection) and mixed with treated surface water. Plans call for increasing capacity to 500 million gallons (Saxon, personal communication). The Mt. Pleasant Waterworks uses reverse osmosis to treat approximately 400 to 500 gaVmin (less than 1 mgd) of water withdrawn from the Cretaceous Middendorf Aquifer. Excess water is injected i11to the Santee Limestone, a Lower Floridan equivalent, allowing the reverse osmosis system to operate at a constant rate. The Grand Strand Water Authority serves the seasonal peak demand of Myrtle Beach by injecting treated surface water into the Cretaceous Black Creek Aquifer. The U.S. Geological Survey has been testing an emergency ASR system for the City. of Charleston to provide water during severe weather when the old distribution system typically experiences problems. This system is somewhat unusual in that it will rely on one time injection of treated surface water into the Santee Limestone. In Georgia, the state legislature has instituted a moratorium on ASR permitting in order to allow the Georgia Environmental Protection Division (GAEPD) to consider the benefits and consequences of ASR in the coastal area. Additionally, the GAEPD is interested in the utility of ASR in managing salt water intrusion in the vicinity of Savannah and Brunswick. 1.2 Report Objective and Approach The purpose of this report is to identify environmental impacts that might arise from ASR operations in the Floridan Aquifer of coastal Georgia and to identify possible me.ans by which impacts could be mitigated or managed. For this report, environmental impacts are taken to be any situation or circumstance that has the potential to cause harm or damage to human health or the environment, including: Physical impacts such as flooding, loss of well yield, and ground destabilization effects (such as ground heave, subsidence, or hydraulic fracturing); Water quality impacts, such as concentrations of chemicals or micro-biological organisms that are in excess of those currently permitted in drinking water. To identify potential impacts and mitigation measures, Golder Associates Inc. (Golder) reviewed literature describing the hydrogeology and hydrogeochemistry of the Floridan Aquifer of coastal Georgia and assessed critical features of the ~uifer system relative to ASR. Floridan Aquifer characteristics were then compared to theoretical and actual descriptions of ASR processes, as documented in peer-reviewed journals, conference proceedings, published and unpublished reports and on the internet. Owing to marked differences in Floridan Aquifer hydrogeology, the potential for ASR-related environmental impacts is discussed in terms of the northern (Savannah) and southern (Brunswick) coastal areas . Golder Associates - - - ----- ----- Georgia Geologic Survey Dr. William McLemore .; 3 ~ April2001 003-3019.002 In identifying ASR impacts and mitigation measures, Golder made several ,assumptions, as directed by GAEPD: Any ASR system will require a permit from GAEPD; ASR permit applicants will have to _perform site specific investigations under the direction of qualified geologists, hydrogeologists, and engineers to address the potential for adverse environmental impacts; Only entities with sufficient capital to invest in appropriate operational facilities, staffing, and operator training will be permitted to develop ASR; Any water injected into the Floridan Aquifer will meet State drinking water standards. Water may be injected into the Upper or Lower Floridan Aquifers, but not the Fernandina Permeable Zone. For purposes of this report, impacts resulting from operator error (e.g. accidental injection of i.mproperly treated water) are not emphasized since operator error is possible with any water treatment or distribution system and is not unique to ASR. Golder Associates Georgia Geologic Survey Dr. William McLemore -4- April2001 003-3019.002 -2.0 ASR PHYSICAL AND HYDROCHEMICAL PROCESSES ASR operations initiate physical and hydrochemical processes in the. storage aquifer. Physical processes include deformation of the aquifer host rock and movement of the injected or native ground water. Ground water pressure changes are often associated with physical processes. Hydrochemical processes include alteration of the chemical characteristics of the recharged water (including changes due to chemical reaction with the aquifer host rock) and alteration of the insitu ground water quality. 2.1 Physical Processes No literature was reviewed that identified physical impacts directly related to an operating ASR system. Nonetheless, ASR physical processes could provide an opportunity for environmental impacts, depending on the characteristics of the aquifer, the design and operation of the ASR system, and the presence of nearby sensitive receptors (other production wells). The treated drinking water used for ASR is typically recharged using large-diameter purposefully designed injection wells or modified production wells; These wells allow the water to enter the well via the pump column, sized drop-pipes, drop pipes with flow control valves or direct injection into the annular space between the casing and the pump rising main. Recharge rates are maintained either by gravity flow or pressure in the distribution system; the choice being dependent upon the rest water level in the well and the water level rise or pressure ("head") increase which occurs in response to injection. The head build-up in the well is a function of both the hydraulic properties of the aquifer and the well efficiency; the head build-up in the aquifer is a function of the aquifer properties alone. Similar effects- determine the water level response to . recovery . Storage of recharged water in confined aquifers occurs principally by elastic deformation of the aquifer matrix. However, ASR storage processes are evident as both a head level increase associated with elastic deformation and a displacement of the in situ groundwater by the injected tl water. Typically, the pressure effects are transmitted over larger areas than the change in w~ter quality that is associated with displacement of the in-situ groundwater. Golder Associates Georgia Geologic Survey Dr. William McLemore -5 - April2001 003-3019.002 The shape and properties of the region of increased pressure or water level rise and the recharged water mass,is a function of: Recharge rate and duration (total stored volume); Distribution of aquifer properties (vertically and horizontally); Presence of aquifer boundary conditions; Properties of the in situ groundwater (pressure, temperature, salinity); Pre-existing hydraulic gradients. For a given aquifer geometry, in situ groundwater quality, and well efficiency, ASR operations in higher transmissivity/lower storativity systems produce smaller head changes and more rapid stabilization of head build~up and draw-down than equivalent operations in lower transmissivity/higher storativity systems. In all cases, transmissivity effects dominate over storativity effects. Simultaneous ASR operations in closely spaced wells typically produce head build-ups or drawdowns that are greater than would be anticipated on the basis of the performance of each individual well. This effect arises as a consequence of the superposition of the head changes associated with each well (termed "well interference"). 2.2 Water Quality Processes . The U.S. Environmental Protection Agency reported that there have been no instances where aquifers have become polluted as a consequence of ASR (EPA, 1999a). However, ASR-related changes in water quality can be observed within the stored water, in the mixing zone between the stored and in situ water, and at locations removed from the ASR aquifer and the stored water mass. Physical and chemical processes that may be responsible for such changes include: Within the Stored Water In the Mixing Zone Reactions between constituents in the injected water and the aquifer matrix minerals; On-going reactions between constituents in the injected water; Diffusion of constituents in the injected water into the matrix-held groundwater and vice-versa (in dual porosity aquifers) Reaction between dissolved constituents in the injected water and the in situ groundwater; Hydrodynamic-dispersion of the injected water, including mechanical dispersion and diffusion Golder Associates Georgia Geologic Survey Dr. William McLemore -6- April2001 003-3019.002 At Off-site Locations Pressure displacement of in situ groundwater and migration into adjacent aquifers or surface waters. Golder Associates Georgia Geologic Survey Dr. William McLemore - 7- Apri12001 003-3019.002 3.0 IMPACTS AND IMPACT MITIGATION AQUIFER LOWER FLORIDAN 3.1 Physical Effects No adverse physical environmental impacts are anticipated from ASR operations in the Lower Floridan Aquifer due to: Large thickness of overlying strata (750ft to 1500 ft). The postulated high permeability of the Lower Floridan Aquifer in the southern coastal area. Therefore, the pressure effects arising from injection or recovery are likely to be both small and spread over a large area. The absence of production wells that penetrate the Lower Floridan Aquifer. Consequently, there is little potential for ASR-related ground destabilization, flooding, reduced yield in other wells, or other physiographic or hydrologic impacts. 3.2 Water Quality Effects 3.2.1 Suspended Sediment Formation No data describing the redox conditions in the Lower Floridan Aquifer were available. However, given the widespread occurrence of reducing conditions in the Upper Floridan Aquifer and the origin of freshwater in the Lower Floridan Aquifer as recharge from the Upper Floridan Aquifer, itis considered likely that reducing conditions prevail in the Lower Floridan Aquifer. When treated water containing dissolved oxygen is injected into reducing groundwaters that contain iron or manganese, oxidation of these constituents will result in the formation of oxide and oxy-hydroxide precipitates. In the conduit flow systems ofthe southern coastal region, these precipitates may remain suspended in solution under the infl.uence of high groundwater velocities or turbulent flow. Such suspended material may then adversely impact the quality of groundwater thatis withdrawn from affected portions of the aquifer. ~ The affected portion of the aquifer is likely to be restricted to the mixing zone between the injected and in-situ water in areas where (a) the mixing zone is penetrated by wa~er supply wells and (b) the in-situ ground water contains dissolved iron and manganese. Given the limited development of the Lower Floridan Aquifer for water supply purposes and the likely presence of Golder Associates - - - - - ----------- Georgia Geologic Survey Dr. William McLemore .- 8- April2001 003-3019.002 sulfide in the in-situ groundwater, the potential for adverse impact is small. Additionally, impacts could be effectively managed by a combination of the following measures: Identification of production wells in the vicinity of the mixing zone between the injected and in~situ water; Site specific assessment of the redox conditions and dissolved constituents in the in-situ ground water; Water quality monitoring during ASR pilot testing; Modification of the ASR location, size, and/or operations schedule (injection rate, storage duration, recovery rate, etc.); Relocation of potentially affected production wells if impacts are observed or predicted; Treatment of withdrawn water to remove suspended sediment. 3.2.2 Disinfection By-products In ASR operation, raw water from a surface source or alternative aquifer is treated to drinking water standards prior to injection into the storage aquifer. Residual disinfectant compounds may be present in the injected water, and oxidation of organic matter in the storage aquifer may J>roduce disinfection by-products (DBPs). Some DBPs are believed to adversely affect human health (e.g. trihalomethanes). Under circumstances in which DBPs are generated and accumulate, stored water quality may be adversely affected. ASR provides an opportunity for generation of DBPs beyond that encountered in traditional water supply operations due to the introduction of treated water after disinfection into a medium (the storage aquifer) that may contain organic matter . The potential for forming DBPs is a function of the disinfectant (chlorine compounCis are of . particular concern), disinfection method (concentration, contact time, etc.), the types of organic matter present in the storage aquifer, water temperature, pH, and the concentration of bromide in the in-situ ground water. It is likely that impacts. associated with DBP formation can be effectively managed by: Characterization of the injected and in-situ water quality and the organic matter content of the ASR aquifer matrix material; Modeling and assessment of the potential for DBP formation; ASR pilot testing and monitoring of injected, in-situ, and extracted water; Modification of the disinfection method of the injected water; Injection into a stratum with lower potential for DBP formation; Managing the ASR injection and extraction schedule to promote natural attenuation of the DBPs; Additional treatment of water extracted from the storage aquifer prior to distribution. Golder Associates Georgia Geologic Survey Dr. William McLemore -9 - April2001 003-3019.002 3.2.3 Solute Transport Effects In localized areas of both the northern and southern coastal regions, the Lower Floridan Aquifer is thought to be in hydraulic continuity with the Upper Floridan Aquifer. In the north this is reflected in the hydraulic response of both aquifers to pumping from the Upper Floridan Aquifer. In the south it is suggested by the pattern of saline upconing in Brunswick. If injection into the Lower Floridan Aquifer results in an increase in the head gradient across the Middle Confining Unit, upward flow from the Lower to the Upper Floridan Aquifer may be increased. In such cases, the quality of Upper Floridan Aquifer water may be adversely affected if the quality ofwater migrating upward from the Lower Florida~ Aquifer is poor. The potential for adverse impacts to production wells in the Upper Floridan Aquifer will be a function of the insitu .water quality, local permeability distribution, the size of the proposed ASR system, and the proximity of the system to production wells in the Upper Floridan Aquifer. This suggests that the potential for any adverse impacts are likely to be local and so may be effectively managed by: Characterization of the groundwater quality of the Lower Floridan Aquifer; Assessment of the existing and predicted hydraulic gradients and the permeability of the Middle Confining Unit; Modeling of ground water migration under different operation conditions; ASR pilot testing and monitoring in the Upper and Lower Floridan Aquifers; Identification of local Upper Floridan Aquifer production wells, and monitoring during ASR operation; Alteration of the ASR operation schedule to reduce the potential for upward migration (possibly including relocation to an area where the confining unit is least permeable). Golder Associates e Georgia Geologic Survey Dr. William McLemore - 10- April2001 003-3019.002 4.0 IMPACTS AND IMPACT MITIGATION- UPPER FLORIDAN AQUIFER 4.1 Physical Effects It seems unlikely that substantial physical impacts will derive from ASR in the Upper Floridan Aquifer of the southern coastal region, principally due to a combination of the significant thickness of the overlying Upper Confining Unit and extremely high values of aquifer transmissivity. Under such circumstances, ASR-induced head changes are likely to be small and distributed over a large area, so that ground effects or interference with nearby production well yields are likely to be minimal. By contrast, the lower transmissivity of the Upper Floridan Aquifer in the northern coastal region, combined with the reduced thickness or local absence of the Upper Confining Unit, means that there is a greater potential for ASR-related physical effects. Such effects would arise from the larger head responses that may occur in response to injection or recovery and could include: Uncontrolled overflow from poorly sealed or capped wells or very localized flooding by upward leakage through the Upper Confining Unit; Loss of yield in nearby wells; De-stabilization of deep foundations as a consequence of re-saturation of near surface sediments and an associated loss of mechanical strength; Ground heave or subsidence caused by changing pore-water pressures in near surface sediments; Hydraulic fracturing of confining strata. Cooper-Jacob seeping calculations indicate that the risks are only likely to be significant in areas close to the ASR site, where the resultant potentiometric surface is at or near ground level and where exceptionally . large volumes of water are recharged and rec.overed through .networks of closely spaced wells. This suggests that the potential for any associated impact is likely to be localized and so may be effectively managed by: , . Site-specific characterization of the geology and hydrogeology at the test site; Hydrologic modeling to determine the magnitu~e of the head level changes that are likely to-result from ASR operations; Reducing the amount of injected or recovered water; Modifying the ASR well-field layout so as to increase the distance between adjacent wells . Monitoring foundation movement and ground elevation in the immediate vicinity of injection and recovery wells during pilot testing and operation; Capping and/or properly abandoning unused Floridan Aquifer wells. Golder Associates . \ Georgia Geologic Survey Dr. William McLemore - 11- April2001 003-3019.002 4.2 Water Quality Effects 4.2.1 Suspended Sediment and Disinfection By-products The potential for formation of suspended iron and manganese oxi-hydroxide sediment and DBPs impacts in the Upper Floridan Aquifer and the opportunity for mitigating these impact is similar to the Lower Floridan Aquifer. 4.2.2 Uranium Mobilization and Introduction of Tritium Eocene and Miocene rocks in Georgia frequently contain strata of clay, organic material, phosphates, or dolomites which contain uranium minerals. In particular, concentrations. of the element are found in the phosphate bearing minerals that are distributed throughout the Upper Confining Unit. Given the reducing conditions. in the Upper Flor:idan Aquifer, any uranium that is present is likely to be in the form of the low solubility mineral uraninite. Under circumstances in which the uraninite comes into contact with injected water containing dissolved oxygen, however, oxidation may result in dissolution of the mineral and mobilization of the associated uranium. Where _concentrations of the element accumulate, an ad'-:erse impact on the stored water quality may potentially_ occur. Given that phosphate-bearing minerals are relatively uncommon, except in the Upper Confining Unit, the associated risk is likely to be localized and so may be effectively managed by: Characterizing the mineral assemblages present in the aquifer host rocks and the . confining units, with particular emphasis on identification of uranium bearing minerals in the strata targeted for ASR development; Examine the accessibility of the uranium-bearing minerals to the injected water containing dissolved oxygen and predict dissolution and resultant concentrations of dissolved uranium ions; If necessary, identify alternate locations for the ASR system where uranium minerals are not abundant or case off individual uranium-bearing strata; Operate the ASR system to extend storage time to promote natural reduction of dissolved uranium . Monitor for dissolved uranium during ASR pilot testing and operation. Tritium is a constituent of concern in Savannah River water due to the Savannah River Site nuclear facility upstream. Reported levels of radionuclides in Savannah River water are well Golder Associates Georgia Geologic Survey Dr. William McLemore - 12- April2001 003-3019.002 below regulatory guidelines, so the likelihood of introducing tritium into an ASR system that made use of Savannah River water would appear to be low. In addition, the City of Savannah and other entities already use the Sava'nnah River as a raw water supply. Therefore, the risk of utilizing Savannah River water for ASRdoes not seem to be substantially different than the risk now accepted by existing water users, except that the processes of diffusion exchange and advective transport described below could influence the transport of tritium introduced into the aquifer . 4.2.3 Pyrite Oxidation Although not detected during visual inspection of cores and washed samples (USGS, personal communication), pyrite may be locally present in the clays, silts and sandy clays of the Upper Confining Unit. If groundwater withdrawal from the Upper Floridan Aquifer dewaters the Upper Confining Unit, pyrite may be oxidized, possibly causing adverse sulfate, pH, iron or alkali metal impacts on the quality of the recovered water. The magnitude of the impact will be a function of the amount of pyrite. present, the permeability of the Upper Floridan Aquifer and the Upper I Confining Unit, and the extent to which withdrawals induce dewatering of the Upper Confining Unit. Special attention should be paid to pyrite oxidation in areas where the Upper Confining Unit has already been dewatered by extensive pumping. Impacts from pyrite oxidation may be effectively managed by: Quantify the pyrite content of the Upper Confining Unit strata likely to be affected by the proposed ASR operations; Predict the draw-down likely to be experienced during the extraction of the stored water; If necessary, relocate the ASR system to a more favorable location; Reduce the amount of stored water that is recovered in an individual well; Increase the spacing between extraction wells to minimize exaggerated drawdown caused by well interference; Monitor water quality during ASR pilot testing and operation; 4.2.4 . Advective Transport ,. Poor quality water generated by any of the mechanisms previously described could laterally migrate within the Upper Floridan Aquifer due to: The concentration of flow in large-diameter conduits such as cavities and solution channels in the southern coastal region; The occurrence of steep hydraulic gradients in areas close to Savannah in the northern coastal region; Golder Associates Georgia Geologic Survey Dr. William McLemore - 13- April2001 003-3019.002 The presence of a large number of public and private water supply wells in both the northern and southern coastal regions. The potential for extensive lateral migration of poor quality water could be effectively reduced by: . Employing previously described measures to limit the opportunity to generate poor quality water; Controlling the ASR injection and extraction schedule and well locations to avoid substantial steepening of hydraulic gradients; Monitoring water quality in nearby production wells. 4.2.5 Diffusion Exchange of Solutes Where groundwater flow .in the Upper Floridan Aquifer of the northern coastal region occurs through fractures, the moderate hydraulic conductivity of the unit suggests that these may include a significant number of relatively small-scale features. A group of small-scale fractures has greater surface area relative to the amount of void space versus a large fracture. If the fractured matrix also possesses significant porosity, solute species flux between the fractures and the matrix via the process of diffusion exchange. Under these circumstances, poor quality water that enters the system may partition between the water in the fractures and the matrix-held pore water. Therefore, if ASR introduces or generates poor quality ground water, the poor quality water and/or undesirable constituents may be retained longer than would be predicted for ground water flow in large scale fractures . The options for mitigating the impact of solute exchange and extended retention of poor quality water are the same as those for managing other water quality concerns. In addition, if an acute water quality problem were identified (e.g. accidental injection of poor quality water) it might be prudent to monitor the recovered water for constituents of concern for an extended period. While the process of diffusion exchange could also occur in the Upper Floridan Aquifer of the southern coastal region, the associated impact is likely to be mitigated by the concentration of flow in this system in large-diameter conduits. Golder Associates Georgia Geologic Survey Dr. William McLemore - 14- April2001 003-3019.002 5.0 SUMMARY No instances where aquifers have become polluted as a consequence of ASR have been reported by EPA. In addition, no literature was reviewed that identified physical impacts resulting from an operating ASR. However, physical and hydrochemical processes of ASR can result in . environmental impacts depending on the design and operation of the ASR system, the characteristics of the storage aquifer and confining or interconnected units, and the utilization of other production wells. Potential impacts of ASR in the Floridan Aquifer of coastal Georgia could include: Lower Floridan Aquifer Generation of suspended iron and manganese oxi-hydroxide sediment due to dissolved oxygen in the injected water; Generation of DBP's as a consequence of organic matter oxidation by disinfection chemicals present in the injected water; Increased solute concentrations in the Upper Floridan Aquifer as a consequence of the ASR-induced displacement of poor quality water from the Lower Floridan. Upper Floridan Aquifer Uncontrolled discharge from improperly abandoned wells, loss of yield in nearby production wells, and ground destabilization effects linked to water level changes during injection and recovery; Suspended sediment and DBP generation similar to that described for the Lower Floridan Aquifer; Increased concentration of dissolved uranium due to oxidation of uranium-bearing minerals by dissolved oxygen in the injected water; Increased sulfate and metal concentrations and decreased pH as a consequence of pyrite oxidation in the Upper Confining Unit due to ASR-induced dewatering of the unit; Lateral migration of poor quality water to other production wells due to flow in large diameter conduits in the southern coastal area and steep hydraulic gradients in the northern coastal area; . Diffusion of exchange of solutes between the injected water and the aquifer matrix. r!' In each case, the probability of the impact being realized, the severity of the impact, and the need for and design of impact mitigation measures may be assessed by site-specific investigations for a proposed ASR (Table 1, Table 2). Such investigations would: Describe the local geology, hydrogeology, and hydrochemistry; Golder Associates - Georgia Geologic Survey Dr. William McLemore ~ 15- April2001 003-3019.002 Model the behavior of the aquifer and associated units during alternative injection and recovery scenarios; Define source-pathway-receptor relationships (e.g. the influence of the proposed ASR on other production wells or sensitive hydrologic sy~tems) . Following the initial assessment, pilot testing would be an effective means of validating models, making direct observations of physical and hydrochemical processes, and comparing alternative ASR designs and operating schedules. Finally, monit<;>ring water quality, aquifer characteristics, and ground conditions in potentially sensitive areas during ASR operation would alert operators _ to possible concerns. Such a monitoring program implies effective facility maintenance, staffing, and operator training as a necessary requirement of ASR operation. ln summary, ASR has the potential to be a useful water resource management tool in coastal Georgia. Some concerns have been identified but no environmental impacts have been identified that could not potentially be mitigated. An active permit program administered by GAEPD could insure that pre-construction investigations, pilot testing, and ASR design, operation, and monitoring are adequate to achieve the water resource management benefits while mitigating environmental impacts. Golder Associates TABLE 1 ( 1 of2) Potential Impacts Associated with ASR Operations in the Lower Floridian Aquifer Potential Responsible Region Where Impact Most . Mitigation or Management Strategy Environmental Process(es) Likely to be Experienced Impact Increasing solute concentrations Pressurization ofthe Lower Floridan as a consequence of Areas where the treated water is Characterization of the groundwater quality of the Lower Floridan Aquifer; injected into poor quality in-situ Assessment of the existing and predicted hydraulic gradients and the groundwater, where upward vertical penneability of the Middle Confming Unit; in the Upper Floridan injection and upward migration of poor quality groundwater under the influence of increasing vertical head gradients head gradients are likely to develop as a consequence of injection and where there exists a pathway between the Upper and Lower Floridan Modeling of ground water migration under different operating conditions; ASR pilot testing and monitoring in the Upper and Lower Floridan Aquifers; Identification of local Upper Floridan Aquifer production wells, and monitoring during ASR opei;ation; Alteration of the ASR operation schedule to reduce the potential for upward migration (possibly including relocation to an area where the confming unit is least penneable). Increasing concentrations of disinfection by-products (DBP's) Oxidation of organic matter by (disinfection) chemicals present in the injected water Stored water in areas where the potential for in-situ fonnation of DBP's is high Characterization of the injected and in-situ water quality and the organic matter content of the ASR aquifer matrix material; Modeling and assessment of the potential for DBP fonnation; ASR pilot testing and monitoring of injected, in-situ, and extracted water; Modification the disinfection method of the injected water; Injection into a stratum with lower potential for DBP fonnation; Managing the ASR injection and extraction schedule to promote natural attenuation of the DBPs; Additional treatment of water extracted from the storage aquifer prior to distribution. -- ---- ---- -- Generation of suspended sediment and increasing turbidity TABLE 1 (continued 2 of2) Oxidation of any dissolved iron or manganese that is present in the in-situ groundwater The mixing zone between the stored ~ite s~eci?c assessment of the redox conditions and dissolved constituents water and in-situ groundwater in m the m-s1tu ground water; areas where the in-situ groundwater Identification of production wells in the vicinity of the mixing zone between contains dissolved iron or the injected and in-situ water; manganese. Water quality monitoring during ASR pilot testing; Modification of the ASR location, size, and/or operations schedule (injection rate, storage duration, recovery rate, etc.); Relocation of potentially affected production wells if impacts are observed or predicted; Treatment of withdrawn water to remove suspended s~diment. TABLE 2 ( 1 of3) Potential Impacts Associated with ASR Operations in the Upper Floridian Aquifier Potential Environmental Impact Flooding, loss of yield and ground destabilization Responsible Process(es) Water level changes associated with injection and recovery Increasing solute concentrations Lateral migration of any poor quality groundwater that enters the Upper Floridan from the Lower Region Where Impact Most Likely to be Exp_erienced Mitigation or Management Strategy Regions close to the ASR well(s) in Site-specific characterization of the geology and hydrogeology at the test areas where either the permeability site; of the Upper Floridan aquifer is relatively low, large quantities of Hydraulic modeling to determine the magnitude of the head level changes that are likely to result from ASR operations; treated water are injected and recovered or where the Upper Confming Unit is thin or absent. Reducing the amount of injected or recovered water; Modifying the ASR well-field layout so as to increase the distance between adjacent wells. Monitoring foundation movement and ground elevation in the immediate vicinity of injection and recovery wells during pilot testing and operation; Capping and/or properly abandoning unused Floridan Aquifer wells. Wells with capture zones that intersect pathways between the Upper and Lower Floridan through which poor quality groundwater could migrate from the underlying Lower Floridan. Employing measures described in Table I to limit the opportunity to generate poor quality water; Controlling the ASR injection and extraction schedule and well locations to avoid substantial steepening of hydraulic gradients; Monitoring water quality in nearby production wells . Extended monitoring if diffusion exchange is a concern. TABLE 2 (continued 2 of 3) Increasing concentrations of disinfection by-products (DBP's) Oxidation of organic matter by (disinfection) chemicals present in the injected water Stored water in areas where the potential for in-situ formation of DBP's is high Characterization of the injected and in-situ wa_ter quality and the organic matter content of the ASR aquifer matrix material; Modeling and assessment of the potential for DBP formation; ASR pilot testing and monitoring of injected, in-situ, and extracted water; Modification the disinfection method of the injected water; Injection into a stratum with lower potential for DBP formation; Managing the ASR injection and extraction schedule to promote natural attenuation ofthe DBPs; Additional treatment of water extracted from the storage aquifer prior to distribution. Introduction of tritium and increasing concentrations of uranium Oxidative dissolution ofuranite Stored water in regions where dissolved oxygen is likely to come into contact with uranite, including by migration into the base of the Upper Confming Unit. ' ---- ------- Characterizing the mineral assemblages present in the aquifer host rocks and the confming units, with particular emphasis on identification of uranium bearing minerals in the strata targeted for ASR development; Examine the accessibility of the uranium-bearing minerals to the injected water containing dissolved oxygen and predict dissolution and resultant concentrations of dissolved uranium ions; If necessary, identify alternate locations for the ASR system where uranium minerals are not abundant or case off individual uranium-bearing strata; Operate the ASR system to extend storage time to promote natural reduction of dissolved uranium. Monitor for tritium and dissolved uranium during ASR pilot testing and operation. TABLE 2 (continued 3 of3) Increasing sulphate and trace metal concentrations and decreasing pH Dewatering of Upper Recovered water where recovery Quantify the pyrite content of the Upper Floridan Aquifer and Upper Confming Unit strata results in dewatering of the Upper Confming Unit strata likely to be affected by the proposed ASR operations; during recovery of Confming Unit or stored water the stored water and where injection raises the water Predict the draw-down likely to be experienced during the extraction of the stored water; oxidation of pyrite or level in the Upper Floridan into If necessary, relocate the ASR system to a more favorable location; mobilization of previously dewatered Upper Reduce the amount of stored water that is recovered in an individual well; historical pyrite Confming Unit strata that originally Increase the spacing between extraction wells to minimize exaggerated oxidation products contained pyrite. drawdown caused by well interference; Monitor water quality during ASR pilot testing and operation; ... FIGURES CD RAW WATER WITHDRAWAL FROM RIVER RAW OR POTABLE WATER WITHDRAWAL FROM ALTERNATIVE SUPPLY AQUIFER 0 WATER TREATMENT PLANT 0 TREATED WATER TO USERS TREATED WATER TO RECHARGE WELL TREATED WATER INJECTED INTO STORAGE AQUIFER RECHARGE DURING LOW DEMAND PERIOD OR WET SEASON NO OR REDUCED WITHDRAWAL FROM RIVER NO OR REDUCED WITHDRAWAL FROM ALTERNATIVE AQUIFER WATER TREATMENT PLANT {;\ TREATED WATER TO \::J USERS (INCLUDING RECOVERED WATER) RECOVERED WATER ADDED TO DISTRIBUTION SYSTEM WITH MINOR TREATMENT (e.g., DISINFECTION) STORED TREATED WATER RECOVERED FROM AQUIFER WITHDRAWAL DURING PEAK DEMAND PERIOD OR DRY SEASON CUE NT/PROJECT TITLE Atlanta, Georgia DRAWN GAEPD/ ASR/GA CONCEPTUAL ASR OPERATION RJS DATE SCALE FILE NO. 12/00 . N.T.S. 003-3019 JOB NO. DWG NO. 003-3019 REV. NO. SUBTITLE FIGURE NO. APPENDICES APPENDIX A Summary of Documented Environmental Impacts of ASR Operation (. ueorgta,ueotogtc :survey Dr. William McLemore - A-1- April2001 003-3019.002 . APPENDIX A Summary of Documented Environmental Impacts of ASR Operation A.l Physical Impacts Physical impacts associated with ASR operations theoretically include flooding, interference with nearby production wells, and ground stability effects. No examples of any such effects could be found in the literature, although routine assessment of the associated risks was apparent. A.2 Water Quality Impacts Hydrogeochemical processes that have the potential to impact ASR water quality include reduction-oxidation reactions, dissolution, and ion exchange. These processes may act singly or in combination, with the associated water quality changes being observed in either the stored . water mass or the mixing zone between the stored water and the in situ groundwater. Solute transport processes that may subsequently act to influence the movement and distribution of ASR-related poor quality water include advection, mechanical dispersion, and diffusion. Examples of ASR facilities where there has been an observable (but not necessarily critical) hydrogeochemical impact on the quality of either the recovered water or in situ groundwater include: I Tri;-halomethane (THM) impacts on the quality of water recovered from an ASR scheme in the basin sediments of Las Vegas, NV (Thomas et al, 2000 and Landmeyer et al, 2000); Nickel and arsenic concentration impacts on the quality ofwater recharged to a series of sandy aquifers in the Netherlands (Stuyfzand, 1998a); Iron concentration and low pH impacts on the quality.ofwater recharged to the Magothy aquifer of Long Island, NY (Ragone and Vecchioli, 1975); e Sulfate, magnesium, potassium and total hardness impacts on the quality of water r~covered from an ASR scheme in the London Basin Chalk (Flaviri and Joseph, 1981 ); Sodium, potassium and ammonium concentration impacts on the quality of water injected into marginal quality groundwater in the London Basin Chalk (Moncaster and Cook, 1999); Recovery of water contaminated with excessive quantities of manganese from an ASR scheme in Chesapeake, Virginia (lbison et al, 1995); Dissolution driven suspended sediment contamination of water recovered from an ASR scheme in Australia (Rattray et al 1986). APPENDIXB Floridian Aquifer Hydrogeology Georgia: Geologic Survey Dr. William McLemore APPENDIXB Floridan Aquifer Hydrogeology April2001 003-3019.002 B.l GENERAL The Floridan Aquifer comprises a "vertically continuous sequence of carbonate rocks of generally high permeability that are of Tertiary age, hydraulically connected in varying degrees, and whose permeability is generally several orders of magnitude greater than that of the rocks that bound the system above and below" (Miller, 1986). I The system underlies all of Florida, southeast Georgia and adjacent parts of Alabama and South Carolina. In Georgia, the Floridan Aquifer strata outcrop parallel to the fall line and dip to the south and southeast. The thickness of the sequence increases from less than I00 ft at outcrop to more than 2,000 ft at the (Atlantic) coast. In the coastal areas, the aquifer is divided into two permeable sub-units, the Upper and Lower Floridan Aquifer. These sub-units are separated by a confini~g unit of variable hydraulic properties. Groundwater recharge to the coastal Georgia system occurs as a combination of groundwater inflow from updip or adjacent units of the Floridan Aquifer and natural or induced leakage through the upper confining unit. The predominant direction of flow is from west to east in the south aitd from north-west to south-east in the north, in both cases from topographically high regions .inland towards pumping centers located at the coast. Groundwater discharge occurs both as withdrawal at the coastal pumping centers and, in areas to the south and east, via upward leakage into the upper confining layer. All of the withdrawal in coastal Georgia is understood to be from wells that penetrate the Upper Floridan Aquifer. However, the yield from these wells is sustained in part by upward leakage from the Lower Floridan Aquifer. This occurs as a consequence of both natural and induced head gradients and is locally facilitated by the presence of high permeability flow-paths associated with a series of high-angle faults. Groundwater development and use in coastal Georgia has resulted in a regional decline in the potentiometric , surface and pronounced cones of depression at major pumping centers, notably around Savannah and Brunswick. Water quality in the Floridan Aquifer system varies from a calcium bicarbonate type inland to a calcium magnesium bicarbonate or calcium magnesium bicarbonate sulfate at the coast. In addition, high levels of withdrawal in some parts of the region have resulted in saline intrusion to the aquifer. Consequently, concentrations of chloride are locally excessive. The intrusion occurs both laterally and vertically, with poorer quality water entering the Upper Floridan Aquifer from the areas offshore and from deeper sections of the aquifer, respectively. A brief description of the lithology and hydraulic properties of each of the components of the Florid~ Aquifer system is given below. This is largely derived from Krause and Randolph (1989). . ~ B.2 .UPPER CONFINING UNIT The Upper Confining Unit comprises an interbedded sequence of sand, silt, clay and sandy clay of low permeability. The unit achieves a maximum thickness of 600 ft in the vicinity of Brunswick and thins northwards to less than I00 ft in the vicinity of Savannah. Locally, in the area of, Savannah and Hilton Head Island, the unit has been breached by the effects of erosion with the result that the underlying Floridan Aquifer is exposed. ueorg1a fjeologic Survey Dr. Willi.arn McLemore - B-2- April2001 003-3019.002 Measured values of the vertical hydraulic conductivity of the Upper Confining Unit vary between SE-07 ft/d and 1.1 ft/d, while values estimated from the results of regional aquifer modeling vary between lE-05 ft/d and IE-03 ft/d. Leakance estimates systematically increase from less than lE-06 ft/d/ft in the south to greater than IE-04 ft/d/ft in the north. This trend reflects the decreasing thickness of the unit towards the north and the relatively narrow range of composite or average vertical hydraulic conductivities. B.3 UPPER FLORIDAN AQUIFER In the study area the Upper Floridan Aquifer comprises Oligocene and Late Eocene units including the Suwannee and Ocala Limestone. The former is composed of limestones which vary from soft, chalky and fossiliferous to dense, calcitized, saccharoidal and unfossiliferous. The latter is a white to gray, fossilferous, recrystalized, porous limestone containing large solution cavities .. Wells in the Brunswick area penetrate two permeable zones in the UpperFloridan Aquifer which are both within the Ocala limestone. The upper zone. is between 75 ft and ISO ft thick and contributes up to 70% of the available yield. The lower zone, which locally includes part of the Middle .Eocene Avon Park Formation, is between 15 ft and 110 ft thick and contributes the remaind~r. In the Savannah area, wells also penetrate two permeable zones in the Upper Floridan Aquifer. The upper of these is less than 50 ft thick and lies within basal Suwannee and Upper Ocala strata; the lower is between 25 ft and 75 ft thick and is entir~ly within middle Ocala strata: These two zones contribute 70% of the available yield. Estimates of the transmissivity of the Upper Floridan Aquifer derived from aquifer testing vary between 30,000 ft2/d and 280,000 Wid, while estimates derived from regional aquifer modeling range between 50,000 ft2/d and 250,000 ft2/d. In both cases values decrease to the south and north of Camden County, with extremely high values occurring in the vicinity of Brunswick. Associated estimates of the hydraulic conductivity vary between 80 ftld and 670 ftld. Estimates of the storativity, where these are available, are of the order of 0.0004 to 0.0006. The extremely high values of aquifer transmissivity reflect flow through cavities, cavernous zones and solution channels in the limestone. The majority of these are orientated in the horizontal plane, enhancing lateral permeabilities, although vertical features associated with highangle fault zones are also present. B.4 THE LOWER FLORIDAN AQUIFER AND MIDDLE CONFINING UNIT In the study area the Lower Floridan Aquifer comprises strata of the Lower and Middle Eocene including the Avon Park, Oldsmar, and Cedar Keys formations and the Gosport equivalent. The hydraulic properties of the unit have not been determined, although transmissivity is thought to vary between 2000 ft2/d and 400,000 W/d and to be less than 100,000 ft2/d in areas outside of extreme southeast Georgia. ' ~ In the vicinity of Brunswick, the lower two-thirds of the Avon Park formation and the upper portion of the Oldsmar formation comprise an interbedded sequence of limestone and dolomite in which significant secondary permeability has developed as a consequence of solution activity along bedding planes. By contrast, upper Avon Park strata is composed of a dense, low- permeability recrystalized carbonate. This sub-unit acts to confine groundwater in the Lower Floridan Aquifer, separating it from groundwater in the Upper Floridan Aquifer except in areas where f~ulting allows flow between the two. The vertical hydraulic conductivity of intact Middle Georgia G' eologic Survey Dr. William McLemore - B-3- April2001 003-3019.002 Confining Unit strata is estimated from cores recovered in the Brunswick area to vary between 4E-06 ftld and 5E-05 ftJd. Water level differences across the unit vary between 2 ft and 20 ft but are gene~ally thought to be less than 5 ft. The bas~ of the Lower Floridan Aquifer in the Brunswick area contains an additional semi- confining unit and an underlying cavernous limestone known as the Fernandina Permeable Zone. The hydraulic properties of each of these sub-units are unknown, although the scale of the caverns ih the limestone are such that the transmissivity of the unit is thought to be of the order of 1E06 ft2/d. I ' . In the Savannah area, the Gosport equivalent is composed of a calcareous sand or very sandy limestone. The unit resp~mds to pumping in the Upper Floridan Aquifer and is thus thought to be in hydraulic continuity with the Upper Floridan Aquifer. Properties for the Lower Floridan Aquifer and middle confining. unit in this area are unknown. . I . ,. APPENDIXC . Bibliography ; . i Georgi~ Geologic Survey Dr. Wil,liam McLemore - C-1- April2001 003-3019.002 APPENDIXC Bibliography The fol)owing references are. pertinent to a description of ASR environmental i!Jlpacts and were reviewed in preparing this report. Included in this list are specific literature citations from this report, as well as references of general use. AndreeV, B. M., E.P. Magomedbekov, Y.S. Pak, M.B. Rozenkevich. 1999. Tritium Removal I . from Water Flows and Concentration of Tritium by Isotope Exchange in Systems with Molecular Hydrogen (H2-H20, H2-Pd). Radiochemistry 41, no. 2, (1999): pp. 136. Appelo; C.A.J. and D. Postma. 1996. Geochemistry, Groundwater and Pollution. Rotterdam: i A.A. Balkema, 536 pp. i Aquife~ Storage and Recovery Issue Team (ASRIT). 1999 i Assessrhent Report and Comprehensive Strategy; A Report to the South Florida Ecosystem ' Restoration Working Group, July 1999. Available on the web at I . httf://www.sfrestore.org/teams/asr/documents/asrreport.htm. i Arino, Dwayne Rene. 1996. The removal of tritium from water using counter-current packed col~mns. Thesis (M.S.)-University ofNevada, Reno, 114 p. Barber,; L.B., G.K. Brown, K.R. Kennedy, J.A. Leenheer, T.l. Noyes, C.E. Rostad, and K.A. Thtim. 1997. "Organic constituents that persist during aquifer storage and recovery of I reclaimed water in Los Angeles County, California,'; in Kendall, D.R. (ed) Conjunctive Use of Water Resources: Aquifer Storage and Recovery; Proceedings of AWRA Symposium, ' . ' . October 19-23, Long Beach, California. I . .. I . . Barker,! J.A., R. Mackenzie, and B. Fretwell. 1997. The importance of Matrix Diffusion for ' ASR Implementation in the Chalk Aquifer. Report for CH2M Hill, .UniversitY College I \ Lori don . Beals, D.M. and D.W. Hayes. 1995. Technetium-99, iodine-129 and tritium in the waters of the Sav'annah River site. Science of the Total Environment v 173/174, pp. 10 I. I I Georgia Geologic Survey Dr. w'illiam McLemore -t-2- April2001 003-3019.002 ; i Biererls de Haan, S., J.E. Rae, and A. Parker. 1994. Pyrite oxidation in the Tertiary sands of the I L6ndon Basin. Applied Geochemistryv. 9: pp 161-175. Bottre'll, S.H., P.L. Smart, F. Whitaker, and R. Raiswell. 1991. Geochemistry and isotope systematics of sulphur in the mixing zones of Bahamian blue holes. Applied Geochemistry v. 6(1) pp 97- 104. Breac~, B. and B. Paetsch. 1998. Overview of residual disinfection practice by European water suppliers. Water Supply 16(3-4):25-33 . v Bull, R.J., C.P. Gerba, and R.R. Trussell. 1990. Evaluation of the health risks associated with I disinfection. Crit. Rev. Environ. Control20:77-113 . Burt, .R.A. 1993. Groundwater Chemical_ Evolution and Diagenetic Processes in the Upper Floridan Aquifer, Southern South Carolina and Northeastern Georgia. USGS Water Supply P~per2392 . Campbell, B.G. 2000. Personal communication to Jim Renner, Golder Associates, regarding USGS I teSting ofthe Charleston, South Carolina ASR system. Campl;>ell, B.G., K.J. Conlon, J.E. Mirecki, and M.D. Petkewich. 1997. Evaluation of aquifer ! st9rage and recovery in the Santee Limestone/Black Mingo Aquifer near Charleston, South Colina,l993-95. US Geological Survey, Water Resources Investigations Report 96-4283.. Castro, J.E. and L.R. Gardner. 1997. "A Geochemical Model for the Aquifer Storage and Recovery Project at Myrtle Beach, SC," in Kendall, D.R. (ed.) Conjunctive Use of Water ' . Resources: Aquifer Storage and Recovery Proceedings of AWRA Symposium, October 19- 23, Long Beach, California. CH2MHill. 1997. East Bay Plain Phase 1 ASR Investigation. Technical Memorandum to East ! . . . B~y Municipal Utility District. I i ! I I Georgifi Geologic Survey Dr. William McLemore - C-3- April2001 003-3019.002 Clarke; J.S. 1995. Ground-Water Flow Study in the Vicinity of the Savannah River Site, South ' Carolina and Georgia. USGS Fact Sheet 178-95. Available on the web at: http://wwwga.usgs.gov/publications/fs 178 95/fs 178 95.html Clarke; J.S., W.F. Falls, L.E. Edwards, N.O. Fredricksen, L.M. Bybell, T.G. Gibson, and R.J . Litwin. 1994. Geologic, hydrologic, and water-quality data for a multi-aquifer system in co:astal ~lain sediments near Millers Pond, Burke County, Georgia. Georgia Geologic Survey Information Circular 96, 34 p. ' Davisson, M.L., G.B. Hudson, J.E. Moran, S. Niemayer, and R.L. Herndon. 1998. Isotope tracer ap~roaches for characterizing artificial recharge and demonstrating regulatory compliance. A~nual UC Water Reuse Research Conference, June 4-5, 1998, Monteray, California. ! Daviss~n, M.L., G.B. Hudson, J.E. Moran, S. Niemayer, and R.L. Herndon. 1999. Tracing and ag~-dating recycled waste water recharged for potable reuse in a seawater injection barrier, So~them California, USA. Inti. Atomic Energy Agency Inti Symp on Isotope Techniques in Water Resources Development and Management, Vienna, 10-14 May 1999. Dillon~ P. P. Pavelic, S. Toze, S. Ragusa, M. Wright, P. Peter, R. Martin, N. Gerges, and S. : Rinck-Pfeiffer. 1999. Storing recycled water in an aquifer: benefits and risks. AWWA J. ! Water 26(5) 21-29. I . ' I ! Downi~g, R.A., D.B. Smith, F.J. Pearson, R.A. Monkhouse, and R.L.Otlet. 1977. The Age of l Groundwater in the Lincolnshire Limestone, England and its Relevance to the Flow I Mechanism. Journal ofHydrology v 33: pp. 201~216. Drever, James I. 1988. The Geochemistry ofNatural Waters. Englewood Cliffs, N.J. : PrenticeH~ll . ~ EPA. 1999. Maximum contaminants levels for beta particles and photon radioactivity from man- ' made radioactivity from man-made radionuclides in community water systems, 40 CFR (C~apter 1) 141.16., revised July I, 1999. Georgia Geologic Survey April2001 Dr. William McLemore - C-4- 003-3019.002 l EPA l999a. The Class V Underground Injection Control Study: Volume 21 Aquifer Recharge ru1d Aquifer Storage and Recovery Wells. EPA/816-R-99-014u, Office of Ground Water and Drinking Water. EPA 1999b. Providing Safe Drinking Water In America: 1997 Nation~! Public Water Systems Compliance Report And Update On Implementation of 1996 Safe Drinking Water Act Amendments. EPA 305-R-99-002, April, 1999. Washington, D.C.: U.S. Environmental Ptotection Agency, Office of Enforcement and Compliance Assurance. EPA 2000. Providing safe drinking water in America; 1998 national public water systems co'mpliance report. EPA 305-R-00-002. Washington, DC: U.S. Environmental Protection Agency, Office of Enforcement and Compliance Assurance, available on the web at: ' . . h~p://es.epa.gov/oeca/main/fedgov/compliance/pws98.pdf : . : I Fetter~ C.W. 1993. Contaminant Hydrogeology. New York: MacMillan Publishing Company, 458 pp. Flavi~,I R.J. and J. B. Joseph. 1983. The hydrogeology of the Lee Valley and some eff~cts of ' ) aryificial recharge. Quarterly Journal of Engineering Geology v. 16 : pp 65-82. Ford, D.C. and P.W. Williams. 1989. Karst Geomorphology and Hydrology. London : Unwin Hyman Ltd, I I Fordham, Stephen Myles. 1995. Removal of tritium from water using tritium free water-saturated air. Thesis (M.S.}-University ofNevada, Reno, 211 p. I . . ! I Foster, S.S.D. 1975. The Chalk groundwater Tritium anomaly- a possible explanation. Journal ! . of:Hydrology v. 25: pp 159-165. I . ~ . Foster, S.S.D. and A.H. Bath. 1983. The distribution of agricultural soil leachates in the unsaturated zone of the British Chalk Environmental Geology v. 5(2): pp 53-59. I ' Free~, R.A. and J.A. Cherry. 1979~ Groundwater. New Jer.sey: Prentice Hall. Georgia Geologic Survey Dr. William McLemore - C-5- April2001 003-3019.002 Fugro West Inc. 1998. East Bay injection/extraction groundwater pilot project phase II report to I East Bay Municipal Utility District. 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Water Factory 21 Environmental virus and paksite monitoring. Report to Orange County Water District, Dec 1981. . I Jones, fH.K., D.M.J. MacDonald, and I.N. Gale. 1998. The Potential for Aquifer Storage and R~c' overy in England and Wales. British Geological Survey Technical Report WD/98/26. I Kelso, :Robert Charles. 1994. The removal of tritium from contaminated water using hollow fiber I . membranes. University ofNevada, Reno, 96 p. I I Kinneburgh, D.G., I.G. Gale, P.L. Smedley, W.G. Darling, J.M. West, R.T. Kimblin, A. Parker, J.E. Rae, P.J. Aldous, and M.J. O'Shea. 1994. The effects of historic abstraction of I . . . I gr~undwater from the London Basin aquifers on groundwater quality. Applied Geochemistry v. 9: pp 175-1~5 . Krause, R.E. and R.B. Randolph. 1989. Hydrology of the Floridan Aquifer System in Southeast Ge'orgia and Adjacent Parts of Florida and South Carolina. USGS Professional Paper 1403-D, 65j>p . 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Tracing thb young fraction in gr~undwat,er mixtures iri the Upper Floridan Aquifer near Valdosta, G~orgia. Applied Geochemistry v. 13(8): pp. 995- 1017. . Plummer, L.N., E. Busenburg, S. Drenkard, P. Schlosser, B. Ekwurzel, R. Weppemig, J.B ~cConnell, and R.L. Michel. 1998b. Flow of river water into a karstic aquifer - 2. Dating th~ young fraction in groundwater mixtures in the Upper Floridan Aquifer near ValdosUt, ' Gforgia. Applied Geochemistry v. 13(8): pp. 1017-1043. I i Plummer, LN., M.G. Rupert, E. Busenburg, and P. Schlosser. 2000. Age oflrrigation Water in Ground Water from the Eastern Snake River Plain Aquifer, South-Central Id~ho. Ground ~ater v. 38(2) : pp. 264-284. Pontiqs, F.W. 1993a. Federal drinking water regulation update. Journal of the :American Water ~orks Association v. 85(2): p. 42. Pontius, F.W. 1993b. D-DBP rule to set tight standards. Journal of the American Water Works Association v. 85(11): p. 22. Pyn~. 1 R.D.G 1995. Groundwater Recharge and Wells: A Guide to Aquifer Storage and R~covery. Boca Raton, Florida: CRC Press. Pyne, R.D.G., P.C. Singer, and C.T. Miller. 1996. Aquifer storage recovery of treated drinking I . Wl;lter. : Final Re.port to A WWA Research Foundation, 176p . I Georgia Geologic Survey I Dr. William McLemore :. \ c~1o:. April2001 003-3019.002 Quinones-Aponte, V., K. Kotun, and J.F. Whitley. 1996. Analysis of Tests of Subsurface Inj~ction, Storage and Recovery of Freshwater in the Lower Floridan Aquifer, Okeechobee County, Florida. USGS Open-File Report 95-765 . Ragone, S.E. and J. Vecchioli, 1975. Chemical Interaction During Deep Well Recharge, Bay I Patk, New York. Ground Water v. 13(1): pp. 17-23 . I Rattray, K.J., P.J. Dillon, A.L. Herczeg, and P. Pavelic. 1986. Geochemical processes in I I aq':Jifers receiving injected stonnwater. Centre for Groundwater Studies Report No. 65 I I I Reinh~d, M., W.-H. Ding, and Y. Fujita. 1994. Organic carbon characterization of.advanced trekted wastewater at Water Factory 21, Orange County. Stanford University, Dept. of Civil I . En~ineering, Civil Engineering Technical Report No. 320. i Rittmah, B.E., P.L. McCarty, and P.V. Roberts. 1980. Trace Organics Degradation in Aquifer I Re~harge. Ground Water v. 18(3): pp. 237-243 . I Robert:S; P.V. 1985. "Field observations of organic contaminant behaviour in the Palo Alto Bariands" In: Artificial Recharge of Groundwater, edited by T. Asano. Butterworth Publishers, pp~647-679 . I i Roberti>, P.V., J.O. Leckie, P.L. McCarty, G.A. Parks, R.L. Street, L.Y. Young, M. Reinhard, and R.C. Cooper. 1978. Groundwater recharge by injection of reclaimed water in Palo Alto. S~nford University, Dept. of Civil Engineering, Civil Engineering Technical Report No. 229, I 12lP Rose, ~ 1993. Environmental tritium systematics of baseflow in Piedmont Provine watersheds, Gebrgia (USA). Journal ofHydro1ogy (Mar 15 1993) v. 143 (3/4): pp. 191- . ' I I I I Rosenl1ein, J.S. and J.J. Hickey. 1977. Storage ofTreated Sewage Eftluent and Stonn Water in a S~line Aquifer, Pinellas Peninsula, Florida. Ground Water v. 15(4): pp. 284-293 . I I' I de Ruiier, H. and P. Stuyzland, 1998. "An experiment on well recharge of oxic water into an I anric aquifer" in, J.H Peters et al. (eds.), Artificial Recharge of Groundwater, Proceedings I I Georgia Geologic Survey Dr. William McLemore - C-i i- April2001 003-3019.002 I of ~e Third International Symposium on Artificial Recharge of Groundwater - TISAR 98, I Amsterdam, Netherlands, 21-25 September 1998, Rotterdam : Balkema. I I Sakharovskii, Y. A., M. B. Rozenkevich, B. M. Andreev, E. P. Magomedbekov. 1999. Removal of :Tritium from Water Flows by the Method of Chemical Isotopic Exchange of Hydrogen with Water. Atomic energy= Atomnaia energiia. v. 85 (1): pp. 462. I Sasaki; T. S-1. S-1 Ishii, and M. Senda. 2000. Tritium in [ISO]water, its identification and "I removal. Applied radiation and isotopes v. 52(2000): pp. 175-179. \ I Saxon,~ E., 2000. Personal communication to Jim Renner, Golder Associates, regarding operation I of the Beaufort-Jasper Water and Sewer Authority ASR system. I Sedlack, D.L. 1999. "Pharmaceutically active compounds in the aquatic environment and their i rel~tionship to water re-use" in 9th Biennial Symposium on the Artificial Recharge of Grbundwater, Tempe, Arizona, June 10-12, 1999. I Singer,!P.C., R.D. Pyne, A.V.S. Mallikarjun, C.T. Miller, and C. Mojonnier. 1993. Examining the impact ofaquifer storage and recovery on DBPs. Res. & Tech. 85-94. South Florida Water Management District. 2000. SFWMD web page http://141.232.1.11/org/pld/proj/asr/asrupdate.htm Posted September 22, 1999. I Sprinkle, C.L. 1989. Geochemistry of the Floridan Aquifer System in Florida and Parts of Georgia, South Carolina and Alabama. USGS Professional Paper 1403 -I. I Street)~, M.J. 1998. "Th.e use of modelling to predict the behaviour of ASR systems" in, J.H Pet~rs et al. (eds.), Artificial Recharge of Groundwater, Proceedings of the Third I International Symposium on Artificial Recharge of Groundwater - TISAR 98, Amsterdam, I Netherlands, 21-25 September 1998, Rotterdam: Balkema. I i i Streetly, M.J. and S. Kotoub. 1998. Determination of aquifer properties in northern Qatar for I application to artificial recharge. Quarterly Journal of Engineering Geology v. 31 : pp. 199- 1 209 . ! I Georgia Geologic Survey I Dr. WiHiam McLemore I April2001 003-3019.002 StumJ, W. and J.J. Morgan. 1981. Aquatic Chemistry: An Introduction Emphasizing Chemical Eq~ilibria in Natural Waters. New York: John Wiley and Sons Inc. I ! StuyrzlImd, P.J. 1998a. "Quality changes upon injec.tion into .anoxic aquifers in the. Netherlands: Ev~luation of 11 experiments" in, J.H PeterS et al (eds.), Artificial Recharge of Groundwater, I Pron. Albany i mE. Draper. Ph.D .. At/ant~ a Faga. Atlanta I 1 R. Foote. Alpharetta 1 Fowler, Athens :. Goldfrank. Columbus t Helms. Atlanta 'J. Hill. Roswell' B. Hudson. M.D.. Augusta 1ghes. Savannah W. Isley, Ph. D.. Statesboro zard Jr.. Atlanta' I n Kenny. Atlanta stes Klamon. Atlanta 'pher Klein. Savannah ty Laird Jr. ' 'ontgomery. Rome Mori. Atlanta e T. Olmstead. Atlanta 1 Parker. Atlanta 1dat Roark. Atlanta ~. R;::,:~ :~~~;a ~ariettal i el J. Rumke. Cummmg A. Rutllerford. Sa,annall ~ >anler. Atlanta el M. Sizemore. Atlanta Stoices. Atlanta i lS R. Swift. M.D.. Augusta s H. Tisdale Jr. A 1/anta 1SORY BOARD rnk Barron. Jr. Rome on Bevington. Atlanta ~n T. Buller. Columbus '. Cowan. Peachtree City y Currey Jr. Atlanta y Hale. Atlanta 1 :l. Hardman. M.D.. Af/antH 1 "d C. Harris. A f/anra Jip Humann. Atlanra tA ur:;. Jasper Lev1lclS. Atlanta : la11g. Atl:.mw uer. AtlwJI,J M. Ratc:lillt:!, Atlanta o.~., Sn11th. Dulvtll f Tenenbaum. S.Honna/1 /are. AtliWW Q \Villuttns. Atlanta ted on recyclcevelopm~nt Center ' lilly Edwards :ity of Hi~esville I \I Elfer ! ekylllslapd Authority I: riary Elfn'er :oastal G~brgia Land Trust IJ 1. 3ill Fostet: Jr. tepresent)ng Sea Island :ompanyj Wes Harris Bulloch County Extension Service Dan Hawthorne Mcintosh County Soil Conservation Commission Glen Hoffman Hercules, Inc. John Karrh Effingham County Lamar Keller Savannah Electric Jack Lantz The Landing Golf Courses Dave Kyler Coastal Georgia Center for Sustainable Development Michelle Liotta Fort James Corporation Dean Moss Beaufort-Jasper Water and Sewer Authority Milton Peterman Representing Glynn County Pete Peterson Effingham County Chamber of Commerce Dave Rutherford City of Port Wentworth Doug Shaw The Nature Conservancy Altamaha Bioreserve Deborah Sheppard Mcintosh County Chamber of Commerce 1 Otl1ers m. aI!ttendanee: John C. Bai1~d I . . Jekylllslani:J Authority j Jackie Jackson Fort Stewart Camille Ransom SC DHEC ' Sid Beauchamp The Landin'gs i I i Michael Dale Elliott jones USGS .Harry Jue .Constance Riggins Mcintosh County Chamber of Commerce South Caro)ina Department of City of Savannah Roy Rountree Natural Resources I I ~ Robert G. E>eWin R&R Seaf~od Company Gail Krueger Savannah Morning News Georgia EPD Steve Royer Georgia-Pacific Corporation t: Kenny Durpas Christi Lambert The Nature Conservancy Gary Sharpe City of Sa~annah Gilman Paper Company Tony Foyl~ Tom Matyok Coastal Georgia Center for Don Smith Georgia Squthern University li Sustainable Development South Atlantic Utilities Jeri Gale (; . Patty Mcintosh Jon Sprague The Georgia Conservancy ,I' i! The Georgia Conservancy TSG Water Resources Amy Horton York Phillips Welby L. Stayton Brunswick:News . iI : Coastal Georgia Regional Development Center USGS Rick Krause I USGS, RetI,ired i I I Allan Pulaski The Landings Katherine Zitsch Camp Dresser & McKee I, Opening:Remarks Patty Mcl~tosh, Director of Coastal Programs for The Georgia Conservancy, welcomed panel participants and others/ in attendance, discussed the 'purpose of the meeting, and introduced the presenters and the facilitator.) Dr. Bill McLemore, State Geologist, discussed the use of models in the Sound Science Initiative, ~fforts and costs to date, and how the stakeholder meeting fits into the Sound Science Initiative and lnteri,~, Strategy for Addressing Saltwater Intrusion into the Upper Floridan Aquifer. I ~ I' USGS Overview of Modeling Effort . II John Clark~, USGS Project Manager of the Sound Science Initiative, made a presentation explaining what the ground~ater models can and cannot do. He also gave a historical overview of the movement of saltwater into the Upper Floridan Aquifer, relating that movement to the drop in artesian pressure due to I, pumping over the years to support development. ! USGS mJdeler Dorothy Payne gave a presentation about flow and soiute transport models, modeling II objectives and modeling limitations. She defined a model as a quantified educated guess and said the models ar~ complex because the hydrologic system is complex. She explained how the groundwater flow system is ~onceptualized, how the models are constructed and calibrated, how management scenarios can be applied; and how the models can be verified. She also explained the differences in capability between i\I I ' I! 2 j I I j: I' I i II' . r: . he current models and the next generation of models USGS will use in the aquifer study. The next seneratio~ of models will update the previous models, focusing on confined aquifers. Based on! input from the Groundwater Stakeholder meeting, USGS will look at how to orient the models t<;>: address areas of interest and specific boundaries. The problems and issues highlighted in today's meeting will affect the size and location of the model boundaries. This process encourages stakeholders to think of issues not addressed by the previous models. The new . generati~n of models may or may not be able to answer all of the questions posed. al~o USGS noted the potential that the proposed Savannah Harbor deepening may cause more saltwate~ intrusion into the aquifer. The new models could be used to show the vertical flux of the waterI~table system and m.ay provide more information about the potential for downward movement of saltwater over time. Questionl/concems posed to EPD and USGS by panel participants: Jack Am*son asked about the Snapper Hole. Con~em ras expressed about th~ lack of k~owledge regar~ing agri~ultural pumpage. Dr. McLemore rephed th~t DNR has contract w1th the Agncultural ExtensiOn Serv1ce to calculate pumpage over a fiveyear peri?d by sampling a subset of irrigation systems. The study began in July I 998 . Does agricultural use of groundwater require a permit? EPD responded yes. I i Facilit~ted Discussion I Gail Co~ie, with the University of Georgia's Carl Vinson Institute of Government, introduced herself as the facilitator. She stated that her role was to help the group focus on information needs. She also stated that a se~ond meeting may be needed and that when the information is compiled, results would be sent to EPD andIshared with the Upper Floridan .Aquifer Technical Advisory Committee. After an /opening exercise in which panel participants indicated their expectations for the next generation of models, the facilitator asked each participant to think of questions for the groundwater models in the following terms: . w+ would happen to (object) if(action) takes place in this location (boundary)? The panel participants were asked to break into small groups and discuss groundwater management questio~s in the suggested format, keeping in mind what would make significant changes to life in coastal Georgia[ The group then reconvened and the facilitator recorded the scenarios each group felt should be addressJd by the EPD's models and technical investigations. . i' The following scenarios were posed by participants and recorded by the facilitator: I . I' . 1. What would happen to the Miocene aquifer(s) if it/they were developed? . Whht would happen to the surficial aquifer and surface water bodies, wetlands, etc., if the Miocene aqu,fer(s) were developed? 2. Wh~t would happen to river base flow and freshwater inflow to the estuary and freshwater wetlands if the~e were increased development of the Miocene and surficial aquifers? What would happen to river base flow and freshwater to the estuary and freshwater wetlands for any alternative use scenario? Mo~e generally, what would be the ecological impacts of each scenario? 3. wJIat would be the geological impacts ofpu~ping from the Miocene . aquifer? 3 I II , I: I I, ' !i . II . 4. What would happen 1f groundwater use were reduced bv 50% and surface water used instead? Are surface water sources sufficient to provide this am~unt? What would be the ecological effects of such a;scenario? I 5. What ~vou ld happen to the saltwater interface if specific water conservation actions were implemented (e.g., retrofits)? How much water (mgd) could be saved? What would be the impact of speciti;c reductions in use (e.g., 10%, 20%, 30%) on the saltwater interface? I . 6. What Vo'ould happen to saltwater intrusion and groundwater quantity if certain wells closest to the coast Jnd to the cone of depression were abandoned and withdrawals were relocated to the west where/the aquifer is deeper? Similarly, what would happen to saltwater intrusion and groundwater quantity ifthese wells were abandoned and use shifted to surface water sources at the coast? ~ould 7. What be the effect on existing inland wells (water level, particularly) if use were moved inlandf Scenarios include shifting pumpage from downtown Brunswick to western Glynn County; from Qlynn County to Camden, Wayne, or Mcintosh County; and Chatham County to Effingham Count)' . 8. What ~ould happen to saltwater movement into Hilton Head if 5 mgd of freshwater were injected as a barrier on the north end of Hilton Head Island? . _ 9. How much water can be pumped out of existing wells in Glynn County and still have the Floridan aquife~ reach a steady state (steady state in terms of groundwater level and salt concentration)? Simil~rly, how much can be pumped from existing wells in Chatham County with the Floridan reachipg a steady state? Moreover, are the conditions at that steady state acceptable? I0. What ~ould be the quantity and quality effects in Chatham and the surrounding areas from unchanged withdrawals in a) Chatham County or b) the study region? ~ould 11. What be the effects on biological functions of unchanged withdrawals region-wide? I. 12. What is the local effect on saltwater movement due to wells in southern Bryan, southern Effingham, and all counties in the study area? That is, was the cap on withdrawal put in place because of contributions to localized saltwater impacts or because of contributions to impacts elsewhere? 13. What kre the potential impacts of existing open-bore wells along the Georgia coast? I 14. Whatlhappens during aquifer storage and recovery (ASR)? That is, what happens to inovefent of stored water, quality of stored water and quality of natural water under ASR? What; are the effects locally? What is the localized movement? What are the effects across the fUll sphere of influence? How far does the sphere of influence extend? Other include: -effects of mixing aerobic and anaerobic waters . -geoc~emical effects on the aquifer itself (on the limestone formations); -effects of prior treatment; and -mixi~g effects in general. ! 15. What !would he the flow scenarios (short-term and long-term) under major drought conditions? I - . 16. What ;would happen to groundwater and surface_ water quality and quantity with continued alteration of wetlands (i.e., drain and fill) across the region? I - 17. What ;would happen to the saltwater intrusion due to sea-level rise? I I .,i I . I, ! I i ' 4 Other qurstionslcomments posed by participants: I A few related questions arose during discussion at the meeting and some participants submitted additional scenarios in writing at the close of the session. These questions and comments are listed below: . ! What }vould be the relative cost/benefit of investment in water conservation equipment for major industrial users versus the development of other water sources? . ! What happened to the money allocated in 1995 for offshore wells to be drilled? [Dr. McLemore answered that: money was allocaledfor Tybee and St. Mary's, but not for offshore drilling} I' Concern \vas expressed about the effects of saltwater intrusion in the aquifer on freshwater in the estuaries and the refusal ofDNR's Coastal Resources Division to see the connection . I I Does ground water press.ure or absence of same affect the quantity of fresh water in coastal estuaries? The aryswer to that question should be transferred to the legislature, the Coastal Resource.s Division or Environmental Protection Division of Georgia DNR, and South Carolina DNR. ' What can the new models tell us about the potential of downward saltwater leakage caused by harbor deeperying? I What is the long-term potential for saltwater intrusion impacting the Skidaway wells based on current I . region11l withdrawal rates? . . If the ~hallow aquifer on Skidaway is utilized to reduce demand on the Floridan Aquifer, will the potential for saltwater intrusion be increased? I How s~sceptible is the shallow aquifer to saltwater.intrusiol')? I What would the "head pressure" become for the Floridan Aquifer (knowing what pre-well days I were)?, Would the pressure be reyersed enough to reduce or eliminate the flow of saltwater intrusion if a policy dictates an MGD reduction? If not, what is the purpose of continuing the model building process other than for monitoring if in fact we are not solving what seems to be a futuristic problem? I i Conclus1;on/Adjournment At the closb of the meeting, participants agreed that it would be useful to meet a second time to review the scenarios J!sted above and discuss priorities in the face of limited resources. At that meeting, EPD and USGS willi provide feedback on the scenarios and their suitability for model application. If possible, informatiot;t from the USGS report on previous modeling efforts, currently being finalized, will be provided t() the panel before the next meeting, which will be held late spring. I I . I The meeting was adjourned promptly at 4:00 PM. I . 5 Groundwater Stakeholder Meeting Hosted by The Georgia Conservancy Wednesday, May 17,2000 1:00-4:00 PM Midway, Georgia Meeting Two Summary urpose' he meetihg was held to conclude the work of stakeholders in identifying groundwater management uestions Jnd modeling scc:;narios for input into groundwater models and other technical investigations ;:ing COJlducted under EPD's Sound Science Initiative. The initial meeting was held on ebruarv 2C3, 2000. - j I 1ttendance I ' 'resenters: I )hn Clarke, USGS orothy P~yne, USGS Facilitator: Gail Cowie, University of Georgia, Carl Vinson Institute of Government 'ane/ Pa~ticipants: 1ck Amas;on ea Garden. Seafood Ob Benson I ilynn Co~nty ' I .en Brewt'on :oastal Erivironmental lrganization and .ryan County I .ichard D9uglas .ong Courtty ,J Elfer I ;:kyll lsla~d Authority I 1ary Elfn~r . :oastal G~orgia Land Trust I Kelly Ferda South Island Utilities HHI, SC Wes Harris Bulloch County Extension Service j Richard Johnston Glynn County Lamar Keller Savannah Electric David Kyler Coastal Georgia Center for Sustainable Development Jack Lantz The Landing Golf Courses Michelle Liotta Fort James Corporation Dean Moss Beaufort-Jasper Water and Sewer Authority Pete Peterson Effingham County Chamber of Commerce David Rutherford City of Port Wentworth Deborah Sheppard Mcintosh County Chamber of Commerce )thers in: attendance: .aurie K. Abbott :oastal WaI ter & Sewerage I 'ony Abbptt :onsolidated Utilities I ~am Arora lydrovisibn I ' John C. Baird Jekyll Island Authority Deatre Denion Chatham-Savannah MPC Kenny Dumas City of Savannah 1 Fred Falls US Geological Survey, Columbia, SC Dieter Franz Camp, Dresser & McKee I I I Jeri Gale j: The Georgi~ Conservancy I Christine Griffiths I The Nature, Conservancy I Phyllis Isley Georgia so:uthern University Jean McDowell Chatham-Savannah MPC Patty Mcintosh The Georgia Conservancy Andy Ninnemann Landings Club SteveRoyer Georgia-Pacific Corporation Gary Sharpe Gilman Paper Company Cardwell Smith Army Corps of Engineers Alice Miller Keyes The Georg~a Conservancy Rick Krau~e Hydrovision 1 Gail K.rueger Savannah rytorning News I Judy JenniDgs Sierra Club I I I, Openinfir Remarks Jimmy Otto Mcintosh County Development Authority Camille Ransom SC DHEC Roy Rountree Georgia EPD Jon Sprague TSG Water Resources Steve Walker Georgia Geological Survey James White SC DHEC USGS staff discussed their model scenario report and provided feedback on the 17 scenarios posed by stakeholders at the February 23rd meeting (see list of scenarios and USGS responses attached to this I summary).! Bill McLemore (GAEPD) and Dieter Fr:anz (Camp, Dresser, & McKee) reviewed the surface water assessments underway as part of the Sound Science Initiative. Under contract with GAEPD, a consultant '(Camp, Dresser & McKee) is looking at surface water supplies and storage needs. Their studies wifl address reclaimed water, off-mainstream impoundments, conjunctive surface-groundwater use, and Wfiter conservation opportunities. I I Meeting p~rticipants stressed the importance of protecting minimum flows in the large rivers. The consultant.is evaluating ways to provide water supply during minimum flow periods (e.g., conjunctive surface-gn;mndwater use). Participants suggested that GAEPD and their consultants look at water supply in an envir'onmentally s~lUnd manner, including protection of riverine habitat with provision of water supply (a doncern for the Ogeechee River, in particular). ! . Facilitated Discussion Participants broke into five small groups to review the modeling scenarios developed at the February 23rd meeting. Each group was asked to select up to five scenarios they felt would provide information critical to the future of the region. The following items were selected: r . I Selected b'y four groups a) What ~ould happen to river base flow and freshwater inflow to the estuary and freshwater wetlands if there ~ere increased development of the Miocene and surficial aquifers? What would happen to river base flow and freshwater to the estuary and freshwater wetlands for any alternative use scenario? I More generally, what would be the ecological impacts of each scenario? I Sugge~ted revision: Ecological concepts should be defined and considered up-frpnt in developing scenafios to be studied. For example, what minimum in-streamflow and seasonal.fluctuations are necessary to maintain ecological junctions ofsubject streams? I . I Facilitator's note: This item is closely related to item g, which was selected by two ofthe groups. I I 2 b) What would happen to saltwater intrusion and groundwater quantity if certain wells closest to the coast a~d to the cone of depression were abandoned and withdrawals were relocated to the west where the aquifer is deeper? Similarly, what would happen to saltwater intrusion and groundwater quantity if these wells were abandoned and use shifted to surface water sources at the coast? I Facilitawr s note: Item) includes a related question. Selected by: three groups . c) What ~'ould happen if groundwater use were reduced by various amounts (e.g., 50%) and surface. water u'sed instead? Are surface water sources sufficient to provide this amount? What would be the ecologi,cal effects of such a scenario? I d) What ~ould happen to the saltwater interface if specific water conservation actions were implemented (e.g., retrofits)? How much water (mgd) could be saved? What would be the impact of specifi4 reductions in use (e.g., I 0%, 20%, 30%) on the saltwater interface? e) How m:uch water can be pumped out of existing wells in Glynn County and s~ill have the Floridan aquifer:reach a steady state (steady state in terms of groundwater level and salt. concentration)? Similarly, how much can be pumped from existing wells in Chatham County with the Floridan I reach in~ a steady state? Moreover, are the conditions at that steady state acceptable? I Selected by; two groups f) What would happen to the Miocene and Lower Floridan aquifer(s) if developed as an alternative to the Upper Floridan Aquifer? What would happen to the surficial aquifer and surface water bodies, wetlanqs, etc. if the Miocene aquifer were developed? g) What Jould be the biologial and ecological effects of all scenarios evaluated? EPD must accept that there isla relationship between groundwater and surface water and a compound effect o.n the coastal ecology and estuaries. All water decisions need to be considered as they affect the coastal ecology . h) What i~ the local effect on saltwater movement due to wells in southern Bryan, southern Effingham, and all counties in the study area? That is, was the cap on withdrawal put in place because of contributions to localized saltwater impacts or because of contributions to :impacts elsewhere? i) What h~ppens during aquifer storage and recovery (ASR)? That is, what happens to movement of stored ~ater, quality of stored water, and quality of natural water under ASR? What are the effects locally? What is the localized movement? What are the effects across the full sphere of influence? How far does the sphere of influence extend? I Related issues: effects of mixing aerobic and anaerobic waters; geochemical effects on the aquifer itself (o.n the limestone formations); effects of prior treatment; and mixing effects in general. ! Selected by!one group j) What Would be the effect on existing inland wells (water level, particularly) if use were moved inland?! Scenarios include shifting pumpage from downtown Brunswick to western Glynn County or from Glynn and Chatham counties to Bryan and Effingham counties, respectively. ' Facilit~tor 's note: Related questions are listed on item b above. k) What ~o' uld be the quantity and quality effects in Chatham and the surr~>Unding areas from unchanged withdrawals in a) Chatham County or b) the study region? i I I , . 3 I I Ii , I i i I n summary, participants recommended the following: Asses~ the ecological effects of all use scenarios, particularly effects on river base flow, on wetlands. and on freshwater inflow to estuaries (see items a, c and g above) . 1 Model specific use scenarios listed above (see items b, c, d, f, i and j). I. Asses~ conditions at steady state groundwater levels and chloride concentrations (see item e) . L Specify impacts of current and unchanged withdrawals (see items h and k) . I I . ';onclu~}on/Adjournment rhe facilitator reiterated that the purpose of the two stakeholder meetings was to solicit input specifically or the grdundwater ~odels and technical investigations. Some questions can be answered through these nechanis~s, but others are beyond the scope and will have to be addressed by EPD in another manner. rhe result!ofthe facilitated sessions will be forwarded to EPD, the Upper Floridan Aquifer Technical \dvisory ~ommittee, and meeting participants. ! Jpon an offer from EPD, stakeholders expressed interest in participating in additional meetings to >rovide input as the Sound Science Initiative studies progress and management policies are formulated. rhe Georgia Conservancy agreed to host the meetings and will notify interested parties as they are ;cheduled: I rhe meeting was adjourned at 4:00PM. I I ' I I I 4 USGS Feedback on Stakeholder Modeling Scenarios I ' The foiiO\\:ing scenarios were posed by stakeholders at the February 23'd meeting. USGS reviewed the scenarios to determine their suitability for model application. Their responses appear in italics . . I I ' I. What would happen to the Miocene aquifer(s) if it/they were developed? What ~ould happen to the surficial aquifer and surface water bodies, wetlands, etc., if the Miocene aquif~~(s) were developed? I This question may be addressed by scenario testing with the models, and is within the scope of the propo~ed modeling. I .., What ~ould happen to river base flow and freshwater inflow to the estuary and freshwater wetlands if there \yere increased development of the Miocene and surficial aquifers? What would happen to river base fl,bw and freshwater to the estuary and freshwater wetlands for any alternative use scenario? More ~enerally, what would be theecological impacts of ea~h scenario? t This question may be partially addressed by the models. Differences in groundwater discharge to the surfac~-water body resulting from changes in pumpage can be simulated. Ecological impacts that result }rom these changes cannot be addressed directly by the model. To simulate the particular proceises occurring in the es/Uaries, a more specific model ofthe surficial aquifer would be required. The tifne scale and the length scale are much shorter in the surficial aquifer than in the confined aquifer system, and the unsaturated zone behaves differently than the saturated zone. These conditions should be considered and incorporated into a more detailed surficial aquifer model. HowevIer, this is not compatible with the proposed modeling scope. The modeling results may subsequently highlight or provide a framework from which to build a proper, more accurate surficial mode( 3. What Would be the geological impacts of pumping from the Miocene aquifer? I . . Subsidence and aquifer compaction are not addressable by the type ofmodeling proposed, nor are they u~derstood to be part ofthe scope. 4. What ~ould happen if groundwater use were reduced by 50% and surface water used instead? Are surface water sources sufficient to provide this amount? What would be the ecological effects of such aI scenario? I A det4iled surface water model is not proposed, but impacts on surface water can be addressed in a general manner as described in point #2 above. Ecological effects may be inferredfrom the modeling, but are not directly addressed. Impacts ofpumpage reductions on ground water conditions can bf?I simulated by the models. . . - 5. What ~would happen to the saltwater interface if specific water conservation actions were imple!llented (e.g., retrofits)? How much water (mgd) could be saved? What would be the impact of specific reductions in use (e.g., 10%,20%, 30%) on the saltwater interface? I Scendrio testing using the saltwater transport model will address questions such as these, for specific I . locations. Similar scenarios have been tested using existing ground water models in coastal Georgia (see s~enarios A-2, A-3 in USGS report). I I 5 l i' t I 6. W~at would happen to saltwater intrusion and groundwater quantity if certain wells closest to thd coast and to the cone of depression were abandoned and withdrawals were relocated to th~ west where the aquifer is deeper? Similarly, what would happen to saltwater intrusion an~ ground"vater quantity if these wells were abandoned and use shifted to surface water sources at the coast? I Scbnario testing using the saltwater transport model will address questions such as these, for spJcijic locations; the model will address surface water effects in a general way. Similar scJnarios have been tested using existing ground water models in coastal Georgia. I 7. What would be the effect on existing inland wells (water level, particularly) if use were mdved inland? Scenarios include shifting pumpage from downtown Brunswick to western GlyI nn County; from Glynn County to Camden; Wayne, or Mcintosh County; and Chatham Cdunty to Effingham County. Th~ regional flow model will address these questions through scenario testing. Similar sc~narios have been tested using existing ground water models in coastal Georgia. I 8. What would happen to salt"vater movement into Hilton Head if 5 mgd of freshwater were injected as a barrier on the north end of Hilton Head Island? Thle saltwater transport model could address this.through scenario testing. HJw 9. much water can be pumped out of existing wells in Glynn County and still have the FJbridan aquifer reach a steady state (steady state in terms of groundwater level and salt cobcentration)? Similarly, how much can be pumped from existing wells in Chatham County wifh the Floridan reaching a steady state? Moreover, are the conditions at that steady state . acceptable? T~ese questions can be addressed using transient simulations ofground water flow and I solute transport. Whether these conditions are acceptable or not can then be evaluated by waIter managers. I I0. What would be the quantity and quality effects inChatham and the surrounding areas from u~changed withdrawals in a) Chatham County or b) the study region? TAese will be addressed by the scenario testing ofthe models. 11. w'hat would be the effects on biological functions of unchanged withdrawals region-wide? I I . , The models will not be able to address this directly, but the results may be usefulfor other stfdies regarding this question. . 12. W;hat is the local effect on saltwater movement due to wells in southern Bryan, southern Effingham, and all counties in the study area? That is, was the cap on withdrawal put in pl~ce because of contributions to localized saltwater impacts or because of contributions to irrtpacts elsewhere? I This question can b.e addressed by ground water flow and solute transport modeling. I . 13. ~hat are the potential impacts ~f existing open-bore wells along the Georgia coast? This is a site-specific problem that could be addressed with very high resolution modeling, I but is probably beyond the scope ofthe planned models. 6 14. ~hat happens during aquifer storage and recovery (ASR)? That is, what happens to mpvement of stored water, quality of stored water and quality of natural water under ASR? What are the effects locally? What is the localized movement? What are the I e~fects across the full sphere of influence? How far does the sphere of influence e~tend? Other include: -effects of mixing aerobic and anaerobic waters -g~ochemical effects onthe aquifer itself(on th~ limestone formations); -effects of prior treatment; and -mIix.ing effects in general. Although the models are capable ofevaluating the impact ofaquifer storage and recovery on gr~und water levels and sal/Water intrusion, they are not capable ofemluciting ~ater-quality in!pacls of injected waters. Such questions can be addressed using geochemical speciation a~d reaction-transport modeling, which are not part ofthe planned models. I . . .JS. W,hat would be the flow scenanos (short-term and long-term) under maJor drought conditions? I T~is can be addressed through scenario testing of both the flow and solute transport models by: varying the amounts ofsurficial recharge. ! 16. What would happen to groundwater and surface water quality and quantity with continued alt1eration of wetlands (i.e., drain and fill) across the region? TJis is a specific question that is probably better addressed by smaller scale modeling of su~ficial aquifers that can account for changes that occur in engineered situations: changes in ~urface topography, sediment compaction, etc. I 17. WhI at would ha.ppen to the-saltwater intrusion due to sea-level ri.se? . It is possible to address the effect ofsea level change on the movement ofthe saltwater.fr~shwater interface, but the time scale ofa sea level change ofsufficient magnitude to affect thJ interface (thousands ofyears) is likely to be many times greater than the time scale of interest to management problems (one hundred years); l 7 I I I USGS response to summary of stakeholder recommendations 2?,I I July 2000 . I I The s~mmary of stakeholder recommendations is concise and specific and provides reconhnendations that are generally achievable by, and are appropriate to the scope of the I modelIing study. Our response to the f.our recommendations follows: I ! ( 1) ~ssess the ecological effects of all use scenarios, particularly effects on river base flow, jon wetlands and on freshwater inflow to estuaries: The models cannot address ecolo~ical effects directly, but they can be made to address at least in a general way the .niteracitJ.On between the surface water and ground water. The regw" nal flow model and. subre~ional solute-transport models will each simulate flow in the surficial aquifer, and I can thus simulate interactions with between the ground water and s4rface-water systems, r~:e~:::::~~OW h 1 Wit o r model will include major rivers and streams as part Of the upper I model boundary. The surficial aquifer will be actively modeled and will be I ' allowed to interact with the surface water and the underlying confined and semi- confined aquifers. Data used to characterize this part of the model will be taken, in part, from a stream-baseflow analysis, yet to be performed. The results of this model will not be able to simulate, in detail, individual wetland or estuarine systems because the time and areal scale of the model will be of too coarse a resolution. Despite these limitations, simulations may indicate specific areas appropriate for more-detailed modeling ofsurface water/groundwater interactions. For the Savannah-Hilton Head Island solute-transport model, it is particularly important to characterize the surficial aquifer and interactions between surface water bodies and the confined aquifers. A leading hypothesis for saltwater contamin<~:tion of the Upper Floridan aquifer in this area is thinning or breaching .of the surfical aquifer, both off-shore, and landward of the barrier islands (intra- coastal areas). The areal scale of this model will also be more conducive to characterizing the local estuarine systems. _i -- For the Brunswick solute-transport model, the primary area of concern is upward II, migration of hypersaline water at depth (Fernandina permeable ~one) . I 1 Interactions between the surface water bodies and the confined aquifers are not I likely to be very important, as the aquifers are deeply buried and the overlying confining unit is extremely thick. Nonetheless, the surficial aquifer can be modeled actively, and interaction between the surface water and confined aquifers will be considered. (2) jodel specific use scenarios: The scenarios discussed at the meetings included unchahged (or increased) withdrawals, conservation actions, use of surface water in place I . of gro,und water, redistribution of pumping locations, and redistribution of pumping to other hsable aquifers. Interest was expressed in the resulting effects of these scenarios on of surfaJe-water bodies (as discussed above), on ground-water levels the various aquifers, o~ and saltwater movement. The calibrated models will be capable of evaluating each of I these jmpacts to varying degrees. It should be noted that these ground-water flow and I solutd-transport models will not be able to specifically address the surficial water I resoutces, but, as indicated previously, the effect of changing surface-water flow on the I surficial and underlying aquifer flow systems can be examined. I . i I (3) Aissess ground-water levels and chloride concentrations under steady-state I . . conditions: Transient model simulations will be used to evaluate the maximum quantity I . of ground water that can be removed before the system can no longer sustain a steady- ~ondition. state For the ground-water flow model, the flow system will be stressed to the I point iof assumed unrecoverable loss of aquifer head (incomplete saturation of the confihI ed aquifers). For the solute-transport models, ste.ady state is ach.ieved when the saltwIater front (transition zone) is stationary; which.may occur under entirely different condiItions than steady state. for the ground-water flo.w model. These models may be used to assess the time it takes for a steady state flow system to achieve steady state chloride I I distribution, and the geometry of that distribution. Each of these scenarios will help I . assesk the water-supply potential of the various aquifers . I I I I I I (4) S)pecify impacts ofcurrent and unchanged withdrawals: This is essentially a specific I use sdenario as described under "Model-specific use scenarios". This will be addressed I ; as patIt of model calibrat.ion to current conditions. I i I I . I Modelj Boundaries To facilitate development of specific model scenarios, we offer the following maps I that show the anticipated boundaries for the flow and solute-tr~msport models. ~re Th. ese I subject to change with additional information, directives, or preiiminar.y modeling results. All model boundaries are shown in red. I I . i Regional Flow Model Boundary I I I I I 20 I . Georgia.. ~: , A/Janlic ..---. - I Brunrick Solute Transport Model I i I_ I . I Savannah-Hilton Head Island Solute Transport Model I , I I . ' ...._. I! I I I Beaufort County I c ' . Jasper . <-,----I~- ounty ._ / \~. , Hilton Head Island _.. -. .. _ . Chatham - County Savannah .:.: . Atlantic .............,_ .. .. -~~-.} ,: 0 4 I Georgia beparhnent of Natural Resources I 205 Butler Street, S.E., E~st Floyd Tower, Atlanta, Georgia 30334 Lonice Barrett, Commissioner i Harold F. Reheis, Director Environmental Protection Division October !13, 1999 I John Sibley Prest"denIt The Geo~gia Conservancy 1776 Pei'ts thai tfie 5olute-ttansport codes selected be chosen after a comprehensive analysis of the major prog:rams and available case studies. In this regard, it is recogn.iz.ed that national experts, including the USGS and private companies, be convened, utilizing a facilitator, to analyze the technicaJ issues and make a recommendation regarding the model or models to be used. The expens should attempt to define the expected capability of the model and the expected c:alibration/validation/documentation. The only limitation on the model recommendation would be that thecode is documented and it is aceeptable to the USGS, which is the agency that provides modeling expertise to the States of Georgia,. Florida, and South Carolina as well as local governmental agencies through a variety of joint funding agreemt'nt The general minutes of the convened experts as well as their recommendations should be described in a report . Task #4 Develop three~imensionaL density dependent, transient solute-transport models . for both the Savannah-Hilton Head area and the Glynn County area. The models should be based on the computer codes recommended in Project Two-Task *4. above. Both models also should be integrated and compatible with the recalibrated flow model including the revised estimates of agricultural pumpage and n:configured potentiometric surface at Savannah reflecting the three offshore monitoring wells, The Savannah-Hilton Head model should be capable of estimating travel times for an encroaching salt water wedge (i.e., 2SO ppm, SOO ppm, and 1000 ppm) to reach certain water supply wells on Hihon Head and at SavaDDab from known or suspec:ted entra.Dce points. The Brunswick model should be capable of estimating the salt water flux frcm the Femafina Permeable Zcme to the Lower Floridan and from the Lower Floridan to the Upper Floridan IS well as the chan&e in size of curtail T shaped plume. Sea models should be capable of considering diffusion, ldvecticm. md. mediiDicaJihydroclyuamic dispelsiOD. The results of the modeling and. the ISSitmptions upon which the modeling is based should be deScribed in two reports (one for Savannah-Hilton Head and one for Brunswick). The model also should be made available to i 1 ssctaekneahno.olsd.ers in digital format so that dley may independently perform their own I Project ~euario DeveJopmeut: Scenario Cievelopment involves modeling actual and hypothetical changes in recharge and withdrawals to assess the impact of salt water intrusion. Basically the scenario development attempts tb answer a variety of -what would happen if" questions. Task *1 i Obtain a general consensus on the needed modeling scenarios. The effectiveness of scenario development is dependent on a general consensus that the scenarios being modeled are reasonable and appropriate; therefore. it is recommended that 13 appropriate stalceholders be convened and querried, utilizing a facilitator, regarding ne-eded ~narios. The general minutes of the convened stakeholders and their recommendations should be described in a repon. Task ~2 Model varying pumping and ground-water management scenarios. Depending on the recommendations of the aforementioned convened stakeholders, scenarios would be modeled and the results would be presented in map and Damtive format. Information that should be provided for each scenario should include: a potentiometric map, salt watrz travel times to key wells for tbe Savannah-Hilton Head area, changes in flux and changes in size of the plume in the Brunswick area, and narrative describing modeling assumptions and impacts {i.e., the Hilton Head wedge would reach a certain well in approximately a certain number of years or the ..,... shaped plume at Brunswick would increase in. size by a certain percentage). While the exact number of modeling scenarios is not predictable at this time, for estimating purposes it is anticipated that the total number will be on the order of 200. It is further recommended that upon completion of aD modeling scenarios, that the results be SUIIlii'Wiz.ed in a repon or a series of repons.s Projed FbIur-Impact Analysis:. i. Task 4'1 Validate hydrogeologic rationale for separating the Northern and Central Subareas. i Ground-water flow modeling by the USGS {Professional Paper 1403-D) indicates . I 1 that Upper Aoridan withdrawals north of the Gulf Trough6 have little impact on water levels south of the Gulf Trough. While the Gulf Trough is reasonably well- defined southwest of Statesboro, its e.xi~eDU ~ of Statesboro is DOt well doalmented ExteDskm of the Gulf Trouah from Statesboro to the SaVIDDih Riwr would be JeUOMble jlsdficatiaa b maintwininl tbe JDtesrity of the Nanhem Subela ad Jess Jestrictiw water 111eleplaticDL OD the other bm1. if the Troup does DOt atald Daltheast rl Statesbcro, tbeD it may be appopriate to include portions of Bulloch IDd Saeven counties in the Ceubal Subarea. Validation of the northeast eXtension of the Gulf Trough should be 1ssessod by performing two seismic-reflection profiles, generally perpendicular to the axis of the Trough, and coring three deep borings, w1izing EPD's wire-tiDe coring equipment, along one or near ODe of the seismic profiles, through the confining units and into the carbonate portion of the aquifrz fOr about 100a200 feet. The seismic pronles would define the exmence or Dallelh1ence of any DOrtheastward I ' t1uch d lbe PiDaJ Sn~egy Will be depeMem Cllllbe modelioa ICmlrios dill~ de~oped. Many d these may be analyZed betweeo July I, 2005 when EPD iDitiates ~ d lbe PIDII S~r~~qy IDd December 31, 200S wbieo EPD 8 scheduled 10 fmaJize 1be PiDal Snaqy. In aD Jikibocd,lbe ~qat desc:ribiD& lbe sceaarios wCi:Wd DOC be iDitiated UDiil &her JaDuary 1, 2006. . I 6 ~Gulf Troueb is a subsUrface poJocic feaue tbat sepuates !be Ncnbem.Subuea from lbe CeDiraJ Subarea. 1 I I I 14 I I APPENDIX4 i I I I I Water Quality Control Chapter 391-3-6 I RULES OF GEORGIA DEPARTMENT OF NATURAL RESOURCES ENVIRONMENTAL PROTECTION DIVISION CHAPTER 391-3-6 TABLE OF CONTENTS I 391-3-6-.13 Underground Injection Control I I 391-3-6-.13 Underground Injection Control I (1) PuQ>ose. The purpose of this rule, 391-3-6-.13 is to establish classes of injection wells, pro~ibitions, criteria and standards applicable to injection wells. I (2) Definitions. Amended. All terms used in this rule shall be interpreted in accordance with the aefinitions as set forth in the Act, unless otherwise defined in this Paragraph or in any oth~r Paragraph of this Chapter. All federal regulations adopted by reference are those in effe:ct as of January 1, 2000. (a) "ABandoned well" means a well whose use has been permanently discontinued or which is in a stkte of disrepair such that it cannot be used for its intended purpose or for observation I . purposes. (b) "Aquifer" means a geological formation, group of formations, or part of a formation that is cap~ble of yielding water to a well or spring. (c) "Ar~a of review" means the area surrounding.an injection well or field where migration of the injection and/or formation fluid into an underground source ofdrinking water may occur. (d) "Casing" means a pipe or tubing of appropriate material of varying diameter and weight, I lowered into a borehole during or after drilling in order to support the sides of the hole and I . thus prevent the walls from caving, to prevent loss of drilling mud into porous ground or to I prevent water, gas or other fluid from entering or leaving the hole. I . (e) "Catastrophic collapse" means the sudden and utter failure of overlying strata caused by the renioval of underlying materials. (f) "CJmenting" means the operation whereby a cement slurry is pumped into a drilled hole I and/or forced behind the casing. (g) "CJsspool" meaps a "drywell" that receives untreated sanitary waste containing human exc~eta, and which sometimes has an open bottom and/or perforated sides. I (h) "Cl~ss V septic system" means a "septic system" that handles sanitary and/or other wastes anci has the capacity to serve 20 or more persons a day. I (i) "Cource of drinking water. .r (c) Ex~ept for remediation wells, the injected fluid, upon reaching any underground source of dri~ng water, shall not contain any chemical constituents that exceed any Maximum Co~taminant Levels (MCL) identified in Rule 391-3-5-.18. For Class V septic systems, the flui,d leaving the subsurface distribution system may exceed any maximum contaminant levrls (MCLs) identified in Rule 391-3-5-.18 provided that the MCL is not exceeded upon the!fluld reaching any underground source of drinking water. (d) With the exception of remediation wells, no Class V well shall be located within the inner mattagement zone of any well head protection area after the effective date of this rule. (e) Class V well construction. I, . Subsections 1., 2. and 3. below shall not apply to Class V septic systems as identified in I suBparagraphs 39f-3-6-.13(11)(a)l. and (b.) above: \ I i 14 I I ! I I I 1. T~e person constructing the well shall be a licensed water well contractor in the State of G~orgia in accordance with the provisions of Chapter 5 of Title 12. 2. cdsing shall extend at least five (5) feet into the injection zone unless otherwise specified by the Director. 3. The annular space around the entire length of the casing shall be grouted and sealed to I , pf.event pollution by surface waters, other formation fluids or pollutants into the formation above the injection zone. I 4. Special construction requirements may be specified by the Director or the permit to prevent I cqntamination of an underground source of drinking water. 5. Sptic systems shall be constructed in accordance with the Georgia Department of Human R~sources requirements in 290-5-26. . I (f) An; injection permit may be transferred to any person provided the permittee notifies the Di~ector in writing at least 30 days in advance of the proposed transfer date and the transfer is ~pproved by the Director. (g) A permit issued by the Director may include permit conditions for the monitoring, testing an~ reporting of the injection facility. (h) Plugging and Abandonment. Ex~ept for septic systems identified in subparagraphs 391-3-6-.13(11)(a)l. and 2. above, the following shall apply: 1. T~e Director may order a Class V well plugged and abandoned by the owner when it no longer performs its intended purpose, or when it is determined to endanger underground s~urces of drinking water. 2. It ~hall be the owner's responsibility to have any injection well plugged and abandoned by th~ water well contractor before removing the drilling equipment from the site ifthe well is nqt completed for its intended purpose. 3. It shall be the owner's responsibility to have any exploratory and/or test well(s) constructed f~r the purpose of obtaining information on an injection well site, plugged and abandoned by the water well contractor. 4. Tile entire depth of the well shall be completely filled with cement grout, which shall be in~roduced into the well by a pipe which extends to the bottom of the well and is raised as w~ll is filled, unless otherwise approved by the Director. I l (13) M~chanical Integrity. Amended. Ex~ept for septic systems as identified in subparagraphs 391-3-6-.13(11)(a)l. and 2. above, the following shall apply: (a} An injection well has mechanical integrity if: 1. There is no deteCtable leak in the casing, tubing or packer; and I 2. There is no detectable fluid movement into an underground source ofdrinking water through v~rtical channels adjacent to the injection well bore. I (b) 0Qe ofthe following methods must be used to evaluate the absence ofdetectable leaks under subparagraph 391-3-6-.13(13)(a)l: I 1. Monitoring of annulus pressure; or I . 2. Pr~ssure test with liquid or gas. I ts (c) Th~ methods used to determine the absence of detectable fluid movement into an un~erground source of drinking water shall be the results of a temperature or sonic log. (d) In onducting ' and evaluating the tests for mechanical integ.rity, the owner or operator and the Director shall apply methods and standards generally accepted in the industry. When the owper or operator reports the results of mechanical integrity tests to the Director, the report shall include a description of the test(s) and method(s) used. The Director, in making an evcil.uation shall review monitoring and other test data submitted since the previous eva,luation. (e) The Director may waive mechanical integrity testing of remediation wells in shallow unsonfined aquifers. I I (14) PIJgging and Abandoning Class I, II and III Wells. Amended. I (a) The permittee shall inform the Director in writing of the permittee's intent to abandon an I injection well at least forty-five (45) working days prior to the abandonment. (b) Th~ permittee shall be responsible for the plugging of any injection well that is abandoned. Such plugging shall be in accordance with the criteria identified in Chapter 5 (120-138) of I Title 12. (c) W~Us shall be plugged with cement in a manner which will not allow the movement offluids eitller into or between underground sources of drinking water. I (d) The placement of the cement shall be accomplished under pressure from bottom to top. (e) The well to be cemented shall be in a state of static equilibrium with the mud weight I equalized top to bottom, either by circulating the mud in the well at least once or by a cor#parable method prescribed by the Director, such as the use of a packer, prior to the placement of the cement plugs. I (f) The Director may require ground water monitoring after well abandonment ifcontamination Jn of underground source of drinking water is suspected. (g) The permittee shall certify to the Director within thirty (30) days of plugging that the injcliction well was plugged. according to permitted procedures. I (15) E~ergency Action. If at any time the Director learns that an injection well may cause or has;caused the movements of any fluids containing contaminants into an underground source of drinking water or otherwise adversely affect the water quality or adversely affect the pu~lic health, the Director shall: I (a) Order the injector to cease the operation and take such actions as may be necessary to prevent the 1violation; . (b) Order the injector to take such actions as may be necessary to correct the violation; (c) Tak~ enforcement action; or . (d) Take emergency action upon receipt of information that a contaminant is likely to enter a I . pub,lic water system and present an imminent and substantial endangerment to the health of the public. -' ! (16) Pr.)bibited Wells. Amended. The following types of wells are specifically prohibited I Statewide. I 16 (a) All! Class IV wells that are used to emplace hazardous waste or radioactive waste into the suosurface . I . (b) New drainage wells, except where such wells have been permitted and designed by a I professional geologist or professional engineer registered in the State of Georgia in accbrdance with Chapter 19 or Chapter 15, respectively, of Title 43 ancl the injected fluid do~s not contain any chemical constituent that exceeds any Maximum Contaminant Level I (MCL) identified in Rule 391-3-5-.18. (c) Ne~ large~capacity cesspools are prohibited. A large-capacity cesspool receives sanitary wruhe from multiple dwellings and community or regional establishments serving more than I 20 persons a day. Existing large-capacity cesspools shall be closed by April 5, 2005. Such closure shall include a 30 day notification prior to closure. Well closure shall include rerrioval ofcontaminated materials, disinfection, and plugging with an impervious bentonite- ce~ent mixture. Closure shall be in accordance with criteria identified in the Chapter 5 I (120-138) ofTitle 12. (d). Op6n loop heat pump systems where return water is discharged into a well. (e) Motor vehicle waste disposal wells. . II . . . Authonty p.C.G.A. Sec. 12-5-23 (Ga. L. 1957) p. 629, Sec. 4; Ga. L. 1964, p. 416, Sees. 5, 24; Ga. L. 196~, p. 316, Sec1; Ga. L. 1972, p. 1015, Sees. 1517, 1534; Ga. L. 1972 p. 1266, Sec. 1; Ga. L. 1.974, p. 599, Sees. 6, ~; G.a. L. 1977,,p. 368, Sec. 2. Administrative History: Original . Rule entitle1d "Underground InJection Control was filed on Dec. 9, 1983, eff. Dec. 29, 1983. I I I I I 17 I I I