Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 223
Prospects for Managed Underground Storage Recoverable Water 6 Project Development, Monitoring and Management The general components of a managed underground storage (MUS) system and some of the broad decisions driving the selection of the type of system to be developed are addressed in Chapter 2. Hydrogeological and groundwater engineering issues; water quality and geochemical issues; and legal, institutional, and economic issues related to the development, operation, and management of MUS systems are addressed in Chapters 3, 4, and 5, respectively. This chapter provides an opportunity to address some of the issues that face project proponents (and opponents) and managers of MUS systems that have not been discussed earlier. It should be noted up front that the entire project development, monitoring, and management process is likely to be more successful if a broad approach to water resources planning is taken. As described in Chapter 7, an integrated strategy in which all measures for managing water scarcity are considered carefully in a systematic way is highly recommended. Such a strategy would ideally include metrics to allow comparisons of MUS to other water supply and storage options. It would also take into account watershed-wide water quality management, including control of stormwater, combined sewer overflows, septic tank leaks, agricultural runoff, and coastal water quality issues. The formation of regional water authorities can be a useful step in understanding and incorporating planning in the context of the regional and state water supply and water management options. MUS is not always the solution—or even part of the solution—to water supply and storage challenges. The methodologies described in this chapter assume that all of the options for a given area have been evaluated thoroughly. The list of the geological, hydrologic, geochemical, geotechnical, environmental, public health, water availability, economic, regulatory, and other issues that need to be considered to evaluate the potential suitability of MUS is long; many of these issues have been described in Chapters 3, 4, and 5. No comprehensive MUS site comparison exists; the closest—but an extensive review of aquifer storage and recovery (ASR) planning methodologies—was performed by Brown (2005). The chapter is divided into two main parts. The first part is a summary of the major steps—beginning to end—in the selection, development, management, and oversight of MUS systems. The second part provides an expanded discussion of four key issues that a manager, operator, or regulator may need to consider. These issues are clogging, monitoring (including the use of surrogates or indicators), public perception, and financing.
OCR for page 224
Prospects for Managed Underground Storage Recoverable Water FROM FEASIBILITY TO CLOSURE: STAGES OF AN MUS PROJECT This is a summary of key steps or stages of project development, rather than a “how-to” manual. Many fine references exist on the practical issues of ASR, surface infiltration, and artificial recharge in general. Pyne (2005) discusses in detail the building blocks of an ASR program, including feasibility studies, pilot testing, well design and equipment, plugging issues, and water quality challenges. Brown (2005) does an excellent job of summarizing existing frameworks for both brackish and freshwater ASR projects. He presents a much more detailed framework than the one used in this chapter, including flow charts for the various steps. The Environmental and Water Resources Institute (EWRI, 2001) offers another useful and practical guidebook. The Water Environment Federation and the AWWA (1998) provide an overview of planning indirect potable reuse, health and regulatory considerations, treatment technologies, system reliability, and public information outreach programs. Segalen et al. (2005) give a fine summary on that topic. Several recent scientific meeting proceedings are an excellent source for case studies; notable among these are those of the forth and fifth International Symposia on Management of Aquifer Recharge (Dillon, 2002; UNESCO, 2006) and U.S. Geological Survey (USGS) Artificial Recharge Workshop Proceedings (Aiken and Kuniansky, 2002). Finally, Ruetten (2001) deals in depth with public perception issues. As noted above, there are many different ways to organize an MUS project from beginning to end. The following list is modified only slightly from EWRI/ASCE (2001) Standard Guidelines for Artificial Recharge of Ground Water: Phase I: Preliminary activities (also called feasibility evaluation), including data collection; assessment of regulatory, legal, political, and economic feasibility; and conceptual planning; this phase may also involve environmental assessment and public involvement Phase II: Field investigations and testing of pilot sites Phase III: Design (revision of the conceptual design to reflect results of investigations) Phase IV: Construction and start-up (systems may require cycle testing to develop recharge systems) Phase V: Operation and maintenance Phase VI: Project review and adaptive management Phase VII: Closure
OCR for page 225
Prospects for Managed Underground Storage Recoverable Water Phase I: Feasibility Evaluation The components typically addressed in a feasibility evaluation for an MUS system are summarized as follows: Site assessment—land availability, ownership, proximity to water sources, suitability of aquifers, preexisting groundwater quality, proximity to water use; Legal and regulatory issues—water rights for source water and ownership of water in storage, antidegradation requirements, monitoring requirements; Financial considerations—cost of land, treatment and conveyance facilities, access to capital, availability of grants, loans or other subsidies, costs of operation, and ability to obtain revenue from water users; Purpose of MUS (duration expected) —seasonal or long-term storage, drought protection, meet summer peak demands, or evening out surface water treatment plant flows; Source water availability and quality—Raw surface water, stormwater, recycled water or treated drinking water, high suspended solids load or clear water, quality comparison to existing groundwater; total dissolved solids (TDS), pH, redox potential, trace elements, microbial quality, trace organic contaminants; Treatment needs and existing capacity—desilting to prevent clogging by suspended or settleable solids, pH adjustments or other methods to reduce adverse changes in metal concentrations, reverse osmosis for removal of salts and trace organics, and advanced oxidation for destruction of trace organics; unused capacity of existing treatment facilities; Capture and conveyance facilities needs—stormwater capture impoundments, temporary storage prior to recharge, pipelines or channels for conveyance, pumping needs; and Public perception—outreach program needs, existing perceptions of groundwater quality, different outreach needs depending on source water, especially reclaimed water, different outreach depending on perceptions of water resource needs and impacts of the MUS project, (e.g., drought protection vs. growth inducement). As noted later in this chapter, this step is sometimes left for later in the planning process, to the detriment of all concerned parties. The feasibility of recharging water into the aquifer is perhaps the key issue to explore in a feasibility evaluation. If water cannot be recharged in sufficient quantities, the project will not be possible. For projects that are considering MUS in a geologic area with no prior managed recharge, the feasibility evaluation should analyze available data that can be used to evaluate the feasibility of recharge. It should also propose a course of investigation to assess recharge
OCR for page 226
Prospects for Managed Underground Storage Recoverable Water techniques. A phased course of investigation that spans literature review to field-scale testing is recommended. Field investigations and pilot testing for MUS in areas without prior MUS projects will typically have a greater scope and magnitude than in areas where MUS projects previously have been implemented. Site selection may also be a major issue. Land ownership or nearby land uses may severely constrain the potential locations of recharge facilities. If, however, there is some degree of freedom in site selection, a location suitability assessment may be useful. An example of one kind of suitability assessment is given for ASR in support of the Florida Everglades restoration in Brown (2005). There, an index was used in which potential sites were ranked by weighting eight factors, including such disparate issues as ecological suitability, existing uses of the aquifer, groundwater quality, road density, access to power lines, and aquifer transmissivity. Given the large number of site-specific variables that must be considered at the beginning of the process, decision trees may be a useful aid. An example of such a tool, in this case for selection of the most appropriate groundwater recharge technology (which overlaps Phases I and II), is presented in Figure 6-1. As shown in the figure, the first critical question is what aquifer is being considered for use in the MUS system. If a confined aquifer is being considered, then direct recharge using wells is the only feasible alternative. Direct recharge may include either single-use recharge wells or the dual-purpose wells used in ASR systems. If the goal of a groundwater recharge project is to provide short-term storage and the water must be recovered quickly, ASR systems might be the only feasible alternative. If an existing distribution and well system may be utilized as part of an ASR system, then dual-purpose wells might be the best choice. If an unconfined aquifer is being considered, there are no constraints on the choice of recharge method. For unconfined aquifers, one of the constraining variables on the choice of technologies is the depth to groundwater. As depth to groundwater increases, the cost of recharge wells increases. Depths ranging from 100 to 200 m have often been found to be a cutoff point at which recharge wells become more costly than surface recharge systems; however, site-specific factors such as land and drilling costs may make a different depth more appropriate (Bouwer, 2002). Therefore, the effect of depth should be evaluated for each situation, and land availability might make surface recharge basins more economical even with shallow groundwater depths. In situations where the depth to water is greater than 100 m, particular attention should be given to evaluating whether water recharged at the surface will flow down to the aquifer where it is planned to be withdrawn. If the evaluation indicates that a significant portion of the water recharged will not reach the aquifer in a reasonable amount of time, surface recharge may not be effective. This factor may be particularly important in arid areas where the depth to groundwater is commonly great. The feasibility evaluation should also assess potential impacts on adjacent landowners, including consideration of potential changes in groundwater levels.
OCR for page 227
Prospects for Managed Underground Storage Recoverable Water FIGURE 6-1 Sample decision tree for selection of groundwater recharge method. Another constraining question that must be considered is the availability of appropriate land. Land price and availability are key considerations. In addition, the location of the land and the cost of the distribution system to deliver water to the land are also important. Such impacts could occur whether groundwater levels rise or fall, affecting existing water users or environmental resources (see Chapter 3). Projects should be designed to minimize the degree of impact to the maximum extent practical. For certain types of water sources such as stormwater, land might be required not only for groundwater recharge, but also as an aid to catch and store the water. Governance is another important issue. Regional water authorities can be useful in implementing projects but can also create complicated interagency issues that can get in the way of solving water supply issues. In particular, the relationship between a proposed regional authority and participating local agencies needs to be carefully considered. For example, if a regional water authority is proposed, consideration should be given to the implications of a publicly elected local board delegating its responsibility for water supply development to an interagency regional water authority whose governing board may be appointed rather than elected. In such a case, local agencies may have concerns about a non-elected board setting policy. Is the aquifer confined or unconfined?
OCR for page 228
Prospects for Managed Underground Storage Recoverable Water The regional authority may also have different interests than the local agencies. The manner in which control and ownership of a project is assigned, rights to storage space and stored water are allotted, and related ownership and control issues are decided are important considerations. Thus, regional water authorities may have a useful role in implementing new projects, but the relationships among these authorities and local agencies should be assessed carefully. As listed above, many other factors are involved in feasibility analysis, and this is simply an illustration of an approach that can be taken to guide one through what in the end is a very long and complex decision-making process. Phase II: Components The following text summarizes components typically addressed in an MUS pilot program. Note that these components vary slightly between surface spreading and well recharge systems. Monitoring issues are mentioned only briefly here; they are discussed in more depth later in the chapter. Pilot program goals—evaluate hydrogeology, including permeability, water quality, pressure or water table gradient, travel time, projected hydrogeological effects. Soil borings—evaluate the lithology, depth to groundwater, confining zones, aquifer materials, and aquifer properties; in addition to soil borings, core testing, split sampling, and side wall testing should be considered as some of the viable options to better determine aquifer characteristics. A lithologic log should be prepared and representative cuttings should be preserved when conducting soil borings or well drilling. Sieve analyses and mineral classification should be completed for the sediments recovered during drilling. Tracer studies—employ intrinsic or added tracers, tracer injection, monitoring locations. Monitoring—assess influent water quality, cycle testing for ASR, downgradient testing, native or background characterization (or upgradient). Valve testing (for ASR) —this should often be a preliminary review, with more detailed assessment after the range of flow rates is better defined. Surface infiltration rates (for surface spreading) —the infiltration rate as a function of time is a key parameter to determine feasibility. Injection well recharge rates (for ASR) —where the aquifer or associated aquitards are fractured or highly compressible, high injection pressures can cause hydrofracturing, and alternation of recharge and discharge can lead to irreversible subsidence.
OCR for page 229
Prospects for Managed Underground Storage Recoverable Water Pretreatment evaluation—determine the need for silt removal, pH adjustment, disinfection, et cetera. Modeling evaluation—predict impacts of supplemental recharge on gradients and travel time. Risk Assessment—see Monitoring section of this chapter for an example. In the field testing program, it is important that the design of the investigation consider carefully the time and spatial scales used in the field testing compared to the full-scale MUS project. In most cases, the time and spatial scales used in the field investigations and pilot testing will be smaller than those of the full-scale project. Because of this, it is important to consider how field investigation results can be extrapolated for the full-scale MUS project. The manner in which the field data will be extrapolated should be an important consideration in the design of the field investigations and pilot testing. Key issues to consider in the design of the field testing include the following: How can the recharge water be conveyed to the field test site? How can the testing program be designed to collect enough data to characterize the spatial heterogeneity of the aquifer materials? What kinds of water quality transformations, positive or negative, during storage are likely? Adsorption, filtration, biodegradation, precipitation, dissolution, oxidation and reduction, and formation of disinfection by-products must all be considered. Changes in redox conditions as a result of recharging water are important to assess. When a new source of water is recharged, changes in redox conditions may occur that affect water quality. Particular attention should be given to redox potential changes and potential changes in concentrations of metals. What depths of the aquifer(s) should be monitored? Different aquifer depths may have different hydraulic properties and different water quality, thereby requiring monitoring at multiple depths. Is the well going to be subjected to corrosive environments? What type of well design should be used? What type of well screen and casing materials should be used? What size screen, how many screen intervals, and what formation intervals should be targeted? What are the rates of geochemical reactions that could occur between the recharge water, the aquifer materials, and the native groundwater? Over what length of time should the pilot testing take place to account for these geochemical reaction rates? In the case of brackish or saline aquifers, what are the salinity and the density of the groundwater, and what is the dispersivity of the aquifer at various distances from the well (see Brown, 2005)? How much field data have to be collected to build an accurate model of the full-scale MUS project?
OCR for page 230
Prospects for Managed Underground Storage Recoverable Water Overall, how can the testing program be designed so that it provides sufficient information to select the method of recharge, if more than one method of recharge is under consideration? Overall, the availability of sufficient data for model input is important if the model is to be calibrated with an acceptable level of accuracy. Data should be collected early in the MUS model development and a sensitivity analysis performed to help determine any gaps that may be present in the data. In many cases, multiple, deep monitoring wells should be constructed to obtain the necessary data required for model calibration. However, the cost involved in doing so is quite high. Instead of executing several pilot studies in different areas, an alternative approach is to select one central area and perform detailed studies based on data from a well-equipped monitoring well. The drawback to this method is that the results may not be applicable across a large area if the system is heterogeneous. There is no easy answer to this issue. It must be kept in mind that recharged water may mobilize some metals, inorganic compounds, and organic compounds bound in the aquifer material. The degree of mobilization will be impacted by a variety of factors, including pH, alkalinity, total dissolved solids, temperature, and the concentration of anions and cations already in solution. During operation of the pilot plant, core samples of representative subsurface strata taken in the vicinity of the boreholes could be obtained for use in soil or rock column tests to determine the likelihood of leaching or mobilization of chemicals. Native groundwater also could be collected during operation of the pilot plant for testing to determine any effects of mixing recharged water with groundwater. A decision tree example for Phase II, in this case for treatment requirements prior to groundwater recharge to maintain hydraulic capacity, is shown in Figure 6-2. The type of treatment depends primarily on the choice of groundwater recharge method. For recharge basins, the removal of inorganic suspended solids is the major concern for maintaining infiltration rates. When vadose zone or recharge wells are used, infiltration rates may be reduced by suspended solids (especially critical for the former since there is no mechanism to backwash solids from the wells), biological fouling, or gas entrapment. Gas entrapment is not listed in the decision tree since the solution is often operational and is not a treatment issue. Clogging is a dominant operational issue in MUS and is discussed in more detail both in Phase V (operation and maintenance) and in a separate section later in this chapter. Phase III: Design The following text summarizes components typically addressed in the design phase of an MUS system.
OCR for page 231
Prospects for Managed Underground Storage Recoverable Water FIGURE 6-2 Decision tree for treatment requirements before recharge with respect to hydraulics. Pre-design Results from the field investigations and pilot testing should be evaluated thoroughly and utilized to prepare the project description. Assessment of the depth to groundwater is important to determine whether a vacuum situation could occur. The potential occurrence of a vacuum condition and air entrainment are important when considering the design of recharge wells. The method of recharge and the amount of water to be recharged over defined time scales (e.g., per month, per year), should be defined in the project description. Average and maximum recharge amounts should be estimated. The aquifer zones where the water will be stored and the duration of storage project description should also be defined. Potential losses of water should be estimated. The anticipated quality of the water after recovery should be specified. The type of water treatment before recharge or after recovery should be determined if treatment is required. Any unresolved issues that need to be resolved prior to beginning design should be identified.
OCR for page 232
Prospects for Managed Underground Storage Recoverable Water Additional field investigations should be conducted before commencing design if the unresolved issues are fundamental—for example, if there is significant uncertainty regarding how much water can be recharged or whether adverse water quality changes will occur after recharge. Potential interference among two or more recharge (or production) wells should be carefully investigated in design of an MUS system. This is an ideal area to use models, which depend on the quality of data on hydraulic conductivity, porosity, recharge or leakage, and so forth. Such models may provide fairly good guidance for well placement and discharge limits. For example, Finch and Livingston (1997) discuss the use of a groundwater model for managed underground storage using the La Luz well field in Alamogordo, New Mexico. The pre-design phase typically concludes with preparation of a pre-design report that includes the project description and a description of the primary features of the project, including the facilities to be constructed and the estimated project cost. Phased Design Design should be implemented in phases to allow adding progressive levels of detail; as progressive levels of detail are added, the design should be reviewed rigorously and compared to the project description to verify that the design will allow implementation of the project. The design and operation of the MUS project should be integrated into the overall water management strategy for the area or region. Rigorous review of the design at its initial stages is as important as, and in some respects more important than, review of the design at the final stage. Review in the early stages is critical to minimize subsequent redesign or inclusion of unnecessary or ineffective project elements. If wells are to be constructed, careful consideration should be given to their design and construction. Installation of additional well sounding tubes and gravel feed tubes should be considered for gravel-packed wells. The drilling method should be matched to aquifer conditions. A proper, engineered drilling fluid program is important for drilling methods using drilling fluids. The manner in which well development is conducted after the well has been installed is important to its productivity. Well components such as casing, screen materials, submersible pumps, shafts, and bearings should be considered carefully with respect to corrosion issues. Epoxy-lined, stainless steel, and other materials should be evaluated as needed to minimize corrosion damage. Engineering design of the system that needs to be constructed and specification of the operations and maintenance activities and their cost should be included. An operations and maintenance program should be developed. This should include a written operations and maintenance manual and should describe the water quality monitoring needed to assess the quality of the recovered water and any changes in water quality during recharge or storage that are im-
OCR for page 233
Prospects for Managed Underground Storage Recoverable Water portant to understand. The operations and maintenance program should also account for the upkeep of recharge facilities and the cost of equipment replacement. A key issue, if the project includes a water quality treatment system, is to include sufficient flexibility in the system so that it can be modified if conditions change and additional treatment is needed. If a system is designed to treat the water prior to recharge or after recovery, it needs to have flexibility to be modified if the influent water quality varies beyond the range anticipated during design or if new conditions occur. Flexibility should include the ability to add additional treatment units without having to remove existing units. Availability of space and adaptable piping and instrumentation are important factors to consider. If the project is to be constructed in phases, it may be beneficial to construct the backbone water distribution, electrical, and instrumentation systems for the ultimate size of the project during one of the initial project phases. This can minimize the cost of adding future phases to the project. Phase IV: Construction and Start-up The following text summarizes components typically addressed in the construction and start-up phase of an MUS system. Construction—MUS facilities are sometimes constructed in environmentally sensitive areas; it is important that construction be implemented in accordance with relevant environmental laws and regulations. Commissioning—Generally speaking, this is the process of testing individual components that have been constructed to verify that they function properly; individual components are also tested to verify that they operate in conjunction with related components. Startup—After commissioning is completed, start-up is the process of operating the entire system to verify that performance criteria are met and the system operates reliably. If there is a permit with water quality limits or criteria, startup should include water quality monitoring to ensure that the permit limits are satisfied. One key issue in the construction and start-up phase is to operate the system for sufficient time during start-up to ensure that it is reliably producing water according to permit conditions. If a construction project is near completion and over schedule, there may be pressure to shorten the commissioning and start-up phases to recover time in the schedule. In the event that the commissioning and start-up phases are not properly completed, there is an increased risk of producing water that does not meet permit conditions, which can result in loss of public confidence in the project.
OCR for page 258
Prospects for Managed Underground Storage Recoverable Water where community leaders reside may be perceived better than one where they do not. Establishing that a water agency is a trusted source of water quality is important. While the public generally credits the quality of water to its original source (i.e., a spring, a river, groundwater), the reality is that the safety of water is generally due more to the diligence of a water utility and its investments in testing and treatment. It is a high priority for the water agency to be perceived as the source of that quality. It should be noted, of course, that many of these practices could be also usefully employed by opponents of potable reuse or related projects. Forester (1999) provides a thorough discussion of participatory decision making processes that is quite consistent with these principles. The NRC (2005) also appointed a committee to study the state of knowledge on public participation in environmental decision making, and the committee’s observations similarly stressed the importance of early involvement, open sharing of information, and solicitation of citizens’ opinions in environmental and natural resource decisions. Typically more concerns are raised regarding well recharge systems, partially due to association of these programs with disposal of wastes, versus managed underground storage of water intended for later recovery. Two examples of public involvement and public perception concerns that have arisen in specific MUS projects follow below. Orange County, California The Orange County Water District in Orange County, California, has implemented a successful public involvement program as part of its Groundwater Replenishment System, a managed underground storage project. In addition to community research and program evaluation activities, the public outreach effort included community presentations, appearances on local and public access cable television programs, distribution of materials to and through libraries and other public gathering places, a media relations program, and site and project tours (Wildermuth, 2001). District staff made an average of 120 presentations per year for seven years, to a wide array of civic groups, not only environmental, business, or other obviously interested organizations. The district’s program of information and engagement is generally credited with the general public approval of the groundwater storage project, even though reclaimed wastewater is a significant source of the water being stored for later recovery, blending, and further treatment (Boxall, 2006).
OCR for page 259
Prospects for Managed Underground Storage Recoverable Water Georgia and Florida Public perception of a technology such as ASR can be influenced positively or negatively depending on the degree of open and well-communicated scientific facts and uncertainties. In January 2001, a bill was before the Georgia General Assembly that would place a moratorium on injection of treated river water into the Floridan Aquifer System (FAS) through ASR. This moratorium gained the support of environmental advocates; one politician wanted to make the moratorium permanent and statewide. Another politician recognized that “not enough is known scientifically on whether the technology is safe or potentially harmful” and therefore was uncertain regarding whether “we need to close that door completely right now” (Florida Times Union, January 13, 2001). The bill was not signed into law by the governor (to update before publication). A few months later in Florida, a different message was being communicated. Florida’s ASR operations had existed for several years with few known problems. The recharged water was (and is) required to be treated to drinking water standards. However, legislation before Florida state lawmakers was being proposed to relax water quality standards (e.g., fecal coliforms) prior to recharge into the FAS under certain conditions. Concurrent with these legislative actions was the release of a report by the NRC (2001) that identified issues of uncertainty regarding the role of ASR in the $7.8 billion Everglades restoration plan. Moreover, the New York Times (April 13, 2001) reported that “the state is in the midst of a drought that is the worst in 50 years,” and forecasts say that by 2020 without new sources Florida “would face a water deficit of as much as 30 percent.” As such, the ASR issue was very high profile. As the Florida bill successfully moved forward during the 2001 legislative session, newspaper articles described the bill as allowing “untreated,” “polluted,” or “tainted” water to be injected into the FAS. The bill was amended often to address environmental and scientific concerns as they arose; however, public opposition was building. The message from the legislature differed from that of environmental advocates, and scientists could not provide definitive answers. On April 24, 2001, an editorial in the St. Petersburg Times by a state environmental protection official addressed misperceptions regarding the bill and acknowledged that “opponents of the ASR plan have done a masterful job of offering sound bites that would ignite most who were hearing of the legislation for the first time. The problem is, many of these sound bites are false.” After considerable debate among lawmakers and strong opposition by environmental advocacy groups, the bill was withdrawn. This occurred even though many believed the bill as amended in its final version provided conditions to ensure protection of Florida’s groundwater resources. In Georgia, uncertainty led an effort to remove ASR as a water-resource management option, while in Florida, this established technology experienced a perception “backslide” due to: (1) introduction of a legislative bill that would have benefited from additional input by scientific and technical experts, and (2)
OCR for page 260
Prospects for Managed Underground Storage Recoverable Water communication of a mixture of facts, uncertainty, and inconsistent, misleading, or misunderstood (thus poorly communicated) information. Although the bill rapidly evolved to address concerns, change in public perception outran its progress. Today, the pros and cons of ASR in Florida are widely understood (e.g., NRC, 2001) and have had the benefit of increased scientific study, open communication, and the support of a more informed citizenry. FINANCIAL DRIVERS AND RELATED CONSIDERATIONS Chapter 5 discusses many of the economic issues associated with MUS. Financial considerations are an important component in the development of MUS. Major financial considerations are capital costs and operating costs. Availability of grants, loans, and other subsidies and rate-paying schemes are also other financial considerations. Capital costs include the cost of the land needed for recharge facilities, the cost of constructing recharge facilities, and the cost of surface water retention and conveyance facilities necessary to capture and move the water to recharge facilities. Operational and maintenance costs include cost of the water to be stored, cost of any additional treatment required, cost of acquiring the necessary easements and permits, and monitoring costs. For some systems using reclaimed water, monitoring costs may be a significant factor affecting the final cost of the stored water and the feasibility of the MUS project. The large initial capital costs of such projects may be beyond what can be covered by tax increases, special assessments, or user fees. In such cases, water agencies tend to finance some of the capital costs through bonds, loans, and grants. Of these, bonds have been one of the most commonly employed methods of public finance (Howitt et al., 1999). In some cases, local agencies can utilize tax-exempt bonds as an effective approach to generate funding. With this approach, revenue from the project is used to support the debt. Debt servicing is usually the largest cost component of these projects. The incremental increase in user fees associated with project costs will depend on the cost of the project, the size of the user base, and other factors. A major challenge to MUS is the ability of water providers to secure the financing necessary to develop a project where infrastructure is needed to bring surface water into a site that is feasible for recharge. In some cases, the distance between the location of available surface water and the recharge site may be large and there may be no existing infrastructure to convey the water. In other cases, the cost of land for recharge facilities is prohibitive. Small water providers may be limited in gaining access to such infrastructure and resources without the support of larger-scale water providers or without institutional coordination. Individual states sometimes impose limitations on the powers that local governments have to raise funds to secure needed financing. Even where public entities recognize opportunities to possibly pool resources or coordinate funding,
OCR for page 261
Prospects for Managed Underground Storage Recoverable Water if the legal mechanisms are absent to facilitate this, then project implementation is less likely. As noted in Chapter 5, it is possible for a project to be financially justified but not economically justified. It is also possible for a project to be economically justified but not financially feasible. Important factors that relate to financial feasibility include whether institutional opportunities are available to make a project feasible and whether the legal authority exists to support it. If institutional opportunities are not available or legal authority does not exist to support it, then project proponents may need to evaluate other institutional arrangements. Such arrangements may involve the creation of a new agency to sponsor the project, which may entail increased costs for the project. Historically, surface storage projects have been heavily subsidized through agencies such as the Bureau of Reclamation and various state agencies, especially in the western United States. These subsidies can take the form of grants or low-interest loans for capital improvements, and operating subsidies based on the amount of water stored underground. Issues concerning subsidies have been addressed in Chapter 5. Revenues from MUS projects are obtained through the sale of the stored water. Collecting revenues from water users is a critical financial consideration when planning for MUS. Particularly, it is not clear how MUS will affect water rates. Pyne (2005) identifies two issues: timing of when consumers pay for water stored and not yet recovered; and how costs can be distributed among users with very different demands. Some rate-paying arrangements are evolving as in Pasadena, California, where the city has to provide storage capacity for the Metropolitan Water District of Southern California (MWD) for $3.00 per year per acre foot payable upon recovery (Pyne, 2005). One major incentive cited by ASR facility owners or operators for using this technology is as a means of maximizing the use of water treatment facilities. Shrier (2002) found that ASR facilities intended for potable uses typically treat water to primary and secondary drinking water standards prior to recharge; a few (27 percent of responding facilities) perform some additional pre-recharge treatment at the wellhead (e.g., pH adjustments) to improve injection operations and prevent geochemical interactions between the stored and native waters underground. Most ASR facilities perform no additional post-recovery treatment before introducing the recovered water into their water supplies. 42percent of the responding facilities perform minimal post-recovery treatment prior to recharge (e.g., pH adjustments, iron and manganese removal, filtration or turbidity reduction). Thus, ASR enables facility owners and operators to shift the demand on treatment facilities to non-peak periods by treating the stored water to drinking water standards prior to recharge. The capacity of water treatment facilities is typically designed to meet peak treatment demands. Increasing non-peak use and decreasing peak use of water treatment facilities enable water providers to delay the need for capital investments for increased treatment capacity.
OCR for page 262
Prospects for Managed Underground Storage Recoverable Water Another financial incentive for groundwater-dependent utilities is the way in which wholesale water agencies purchase contracts or rates are structured. For example, in Wildwood, New Jersey, retail water agencies pay for treated water from the wholesale water agency whether they use the water now, store it for later use, or do not use it at all. This rate environment creates an incentive to capture the water during periods of low demand and store it underground for use during periods of high demand. (Wildwood has highly seasonal demand as a coastal resort area with a much greater summer than winter population.) Until 2005 the water stored underground in New Jersey had to be extracted within one year of storage or be claimed by the state. New Jersey has recently allowed studies on water banking for longer periods in the northeast part of the state. In an effort to restore seriously overdrafted regional aquifers the state allows only 85 percent of the water stored underground to be extracted and recovered in designated critical zones of the state. The remaining 15 percent of stored water reverts to the state. To ensure reliable customers for the new 30 million-gallon-per-day water treatment and conveyance facilities, purchase contracts from the regional wholesale agencies in New Jersey American and South Jersey have been structured based on consistent use over 365 days each year. The contracts are essentially take-or-pay contracts. Since the water must be paid for regardless of whether it is used, the water purchasers have virtually no marginal cost for the water during low-demand periods. In some areas the demand rate is set at 90 percent of the full water rate, so the marginal cost is essentially 10 percent of the full cost for the water. Under these circumstances storing the water underground until it is needed the following summer has become an easy decision for Wildwood. In Southern California, the water stored in the ground for MWD can be called under various constraints, but it is generally expected to be stored for several years and available under drought conditions. Such storage is being called upon along with surface storage during 2007 to cope with the severe shortfall in water available from imported water sources, the Colorado River, and the State Water Project. In addition to relatively new storage agreements, MWD has long relied on the availability of groundwater from basins that receive discounted replenishment water. The replenishment water program has involved no formal obligation to increase groundwater withdrawals during periods of need, but agencies such as OCWD have historically cooperated in increasing available groundwater during drought conditions affecting imported water supplies. CONCLUSIONS AND RECOMMENDATIONS Conclusion: The development of an MUS system from project conception to a mature, well functioning system is a complex, multistage operation requiring interdisciplinary knowledge of many aspects of science, technology, and institutional issues.
OCR for page 263
Prospects for Managed Underground Storage Recoverable Water Recommendation: A comprehensive decision framework should be developed to assist in moving through the many stages of project development in an organized, rational way. Professionals from many fields, including chemists, geologists, hydrologists, microbiologists, engineers, economists, planners, and other social scientists should be involved in developing this framework. Conclusion: Growing experience with MUS systems indicates that hydrogeological feasibility analysis including aquifer characterization is one of several important components in their development and implementation. The benefits of doing so include establishing the hydraulic capacity, recharge rates, residence times, and recoverable fraction of the introduced water—all of which help identify the optimum design and viability of the MUS system. Some types of aquifers have matrix, hydrogeologic, and geochemical characteristics that are better suited to MUS systems than others. For example, the aquifer characteristics may dictate recharge, storage, and recovery methods. For an unconfined aquifer, source water can be recharged into the aquifer through recharge basins, vadose zone recharge wells, and deep recharge wells. Stored water can be recovered by production wells or ASR wells, or it can enhance baseflow to neighboring streams. For confined aquifers, however, source water can only be injected through deep recharge wells, including ASR wells. The stored water is usually recovered through ASR wells or downgradient production wells. As another example, water quality benefits are likely to be greater with alluvial systems compared to fractured or dual porosity systems. Recommendation: Multiple factors should be assessed and monitored during design, pilot tests, and operations, including spatial and hydrogeological characterization of storage zones, temporal variation in quality and quantity of recharged, stored, and recovered water and factors that constrain sustainability of the MUS system, including hydrogeochemical, microbiological, and economic conditions. Uncertainty reduction is the ultimate goal. Conclusion: An independent advisory panel can provide objective, third-party guidance and counsel regarding design, operation, maintenance, and monitoring strategies for an MUS project. An independent panel can increase public acceptance of and confidence in the system, if such trust is warranted. It can also be a catalyst for altering a plan if changes appear to be necessary. Recommendation: Water agencies should highly consider the creation of an independent advisory panel or equivalent at an early stage of planning for an MUS system. Conclusion: Relatively little research has been done to characterize the extent of vertical migration of fine-grained particles into the sediments beneath surface spreading facilities. Likewise, the science and technology of cleaning recharge basins is not well developed. Recommendation: Research is recommended to develop new approaches to optimizing surface recharge, including assessing the extent of migration of
OCR for page 264
Prospects for Managed Underground Storage Recoverable Water fine-grained sediment into the subsurface, its impact on the long-term sustainability of surface recharge, and more efficient methods to clean recharge basins after clogging occurs Conclusion: Successful MUS involves careful and thorough chemical and microbiological monitoring to document system performance and evaluate the reliability of the process. Each MUS project needs real-time monitoring of the quality of the waters being introduced into underground storage and of waters being extracted from storage for use. Recommendation: Water quality monitoring programs should be designed on a case-by-case basis to assess water quality changes for elements, compounds, and microbes of concern, optimizing the potential for documenting any improvement in the quality of the source water and to collect samples representing any adverse water quality changes. A proactive monitoring plan is needed to respond to emerging contaminants and increase knowledge about potential risks. Conclusion: New surrogates or indicators of pathogen and trace organic contaminant presence are needed for a variety of water quality parameters to increase the certainty of detecting potential water quality problems through monitoring. The categorization of chemicals and microorganisms into groups with similar fate and transport properties and similar behavior in treatment steps is one approach to streamline the list of potential contaminants to be monitored. It is unclear whether we can continue to rely on total coliform and E. coli indicator bacteria to characterize the microbial quality of water as the drinking water industry has done for decades. Such methodologies will improve the ability of MUS systems of a variety of sizes to engage in sound monitoring practices. Recommendation: Research should be conducted to understand whether we can rely on monitoring surrogate or indicator parameters as a substitute for analysis of long lists of chemicals and microorganisms. Conclusion: Surface spreading facilities sometimes require large amounts of land, particularly where large amounts of water are recharged or the geology is not ideal. Recharge well systems require less land, but may have as many different factors to consider in their placement. Optimization of recharge facility placement is important but not always well understood. Recommendation: If there is some degree of freedom in site selection for recharge wells or basins, a location suitability assessment may be useful in site optimization. Factors such as ecological suitability, existing uses of the aquifer, groundwater quality, aquifer transmissivity, road density, land use and ownership, and access to power lines can be weighed in such an analysis.
OCR for page 265
Prospects for Managed Underground Storage Recoverable Water REFERENCES Aiken, G. R., and E. L. Kuniansky (eds.). 2002. U.S. Geological Survey Artificial Recharge Workshop Proceedings, Sacramento, California. U.S. Geological Survey Open-File Report 02-89. Reston: USGS. Available online at http://water.usgs.gov/ogw/pubs/ofr0289/index.htm. Biuk, N. A., and a. Willemson. 2002. Clogging rate of recharge wells in porous media. Dillon, P. (ed.) Management of Aquifer Recharge for Sustainability. Lisse, The Netherlands: A.A.Balkema, 195-198. Blanc, R., and A. Nasser. 1996. Effect of effluent quality and temperature on the persistence of viruses in soil. Water Science and Technology 33(10-11):237-242. Bloetscher, F., A. Muniz, and G. M. Witt. 2005. Groundwater Injection—Modeling, Risks and Regulations. New York; McGraw-Hill.Boxall, B. 2006. Doubts still swirl to surface. The Los Angeles Times. May 7. Brown, C. 2005. Planning decision framework for brackish water aquifer, storage and recovery (ASR) projects. Ph. D. dissertation, Department of Civil and Coastal Engineering. University of Florida, Gainesville. Bouwer, H.. 2002. Artificial recharge of groundwater: hydrogeology and engineering. Hydrogeology Journal 10: 121-142. Dillon, P. J. (ed.). 2002. Management of Aquifer Recharge for Sustainability. Proceedings of the fourth International Symposium on Artificial Recharge (ISAR 4), Adelaide, 22-25 Sept. 2002. Lisse, The Netherlands: A.A. Balkema Publishers. Drewes J. E., M. Sprinzl, A. Soellner, M. D. Williams, P. Fox, and P. Westerhoff. 1999. Tracking residual dissolved organic carbon using XAD-fractionation and 13C-NMR spectroscopy in indirect potable reuse systems. Vom Wasser 93:95-107. Drewes, J. E., and P. Fox. 2000. Effect of drinking water sources on reclaimed water quality in water reuse systems. Water Environ. Res. 72(3):353-362. Drewes, J. E., and E. Dickinson. 2007. State-of-the-art approaches to monitorunregulated and regulated trace organics in indirect potable reuse. In Proceedings of the 2007 WateReuse Foundation Research Conference, El Paso, Texas, June 4-6.. EWRI/ASCE (Environmental and Water Resources Institute/American Society of Civil Engineers). 2001. Standard Guidelines for Artificial Recharge of Ground Water. EWRI/ASCE 34-01. Reston, VA: ASCE. Finch, S. T., and E. Livingston. 1997. Aquifer storage and recovery study for the La Luz Well Field, City of Alamogordo, New Mexico. In D.R. Kendall (ed.) Proceedings of American Water Resources Symposium on Conjunctive Use of Water Resources: Aquifer Storage and Recovery. Herndon, VA: American Water Resources Association. Forester, John. 1999. The Deliberative Practitioner: Encouraging Participatory Planning Processes. Cambridge, MA: MIT Press.
OCR for page 266
Prospects for Managed Underground Storage Recoverable Water Global Water Research Coalition. 2003a. Endocrine Disrupting Compounds: Occurrence of EDC in Water Systems. Report prepared by the Water Research Commission (South Africa) in cooperation with Kiwa Water Research (Netherlands) and TWZ-Water Technology Center (Germany) for the Global Water Research Coalition, London, UK. Global Water Research Coalition. 2003b. Endocrine Disrupting Compounds: priority list of EDCs. Report prepared by the Water Research Commission (South Africa) in cooperation with Kiwa Water Research (Netherlands) and TWZ-Water Technology Center (Germany) for the Global Water Research Coalition, London, UK. Harden H. S., J. P. Chanton, J. B. Rose, D. E. John, and M. E. Hooks. 2003. Comparison of sulfur hexafluoride, fluorescein and rhodamine dyes and the bacteriophage PRD-1 in tracing subsurface flow. Journal of Hydrology 277(1):100-115. Hartley, T. W. 2003. Water Reuse: Understanding Public Perception and Participation. Alexandria, VA: Water Environment Research Foundation. Her, N., G. Amy, D. McKnight, J. Sohn, and Y. Yoon. 2003. Characterization of DOM as a function of MW by fluorescence EEM and HPLC-SEC using UVA, DOC, and fluorescence detection. Water Res. 37: 4295–4303. Howitt, R. E., J. R. Lund, K. W. Kirby, M. W. Jenkins, A. J. Draper, P. M. Grimes, K. B. Ward, M. D. Davis, B. D. Newlin, B. J. Van Lienden, J. L. Cordua, and S. M. Msangi. 1999. Integrated Economic-Engineering Analysis of California's Future Water Supply. Report for the State of California Resources Agency, Sacramento, California. Available online at http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/Report1/ReportAug99.pdf. Accessed on August 17, 2007. Kolpin, D. W., E. T. Furlong, M. T. Meyer, E. M. Thurman, S. D. Zaugg, L. B. Barber, and H. T. Buxton. 2002. Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance. Environment Science Technology 36(6)1202-1211. Leenheer, J. 2003. Comprehensive Characterization of Dissolved and Colloidal Organic Matter in Waters Associated with Groundwater Recharge at the Orange County Water District. Denver, CO: U.S. Geological Survey. Leenheer, J. A., C. E. Rostad, L. B. Barber, R. A. Schroeder, R. Anders, and M. L. Davisson. 2001. Nature and chlorine reactivity of organic constituents from reclaimed water in groundwater, Los Angeles County, California. Environmental Science and Technology 35:3869-3876. Mansuy N. 1998. Water Well Rehabilitation – A Practical Guide to Understanding Well Problems and Solutions. Mission Woods, KS: CRC Press. Müller, M. B., and F. H. Frimmel. 2002. A new concept for the fractionation of DOM as a basis for its combined chemical and biological characterization. Water Research 36:2643-2655. NRC (National Research Council). 1994. Alternatives for Ground Water Cleanup. National Academies Press, Washington, D.C.
OCR for page 267
Prospects for Managed Underground Storage Recoverable Water NRC. 1998. Issues in Potable Reuse: The Viability of Augmenting Drinking Water Supplies With Reclaimed Water. Washington, DC: National Academies Press. NRC. 1999. Groundwater and Soil Cleanup: Improving Management of Persistent Contaminants. Washington, DC: National Academies Press. NRC. 2000. Natural Attenuation for Groundwater Remediation. Washington, DC: National Academies Press. NRC. 2001. Aquifer Storage and Recovery in the Comprehensive Everglades Restoration Plan: A Critique of the Pilot Projects and Related Plans for ASR in the Lake Okeechobee and Western Hillsboro Areas. Washington, DC: National Academies Press. NRC. 2003. Environmental Cleanup at Navy Facilities: Adaptive Site Management. Washington, DC: National Academies Press. NRC. 2005. Decision Making for the Environment: Social and Behavioral Science Research Priorities Washington, DC: National Academies Press. Olsthoorn, T. N. 1982. Clogging of recharge wells, main subjects. KIWA Communications 72. Paul, J. H., J. B. Rose, J. Brown, E. A. Shinn, S. Miller, and S. R. Farrah.1995. Viral tracer studies indicate contamination of marine waters by sewage disposal practices in Key-Largo, Florida. Appl Environ Microbiol 61(6):2230-2234. Perez-Paricio, A. and J. Carera. 1998, A conceptual and numerical model to characterize clogging. Pp. 55-60 In Peters, J.H., et al. (eds) Proceedings of the Third International Symposium on Artifical Recharge of Groundwater. Rotterdam, Netherlands: A.A. Balkema. Pew Research Center for the People and the Press. 2001. Available online at http://www.people-press.org/questionnaires/trustque.htm. Accessed August 17, 2007. Pyne, R. D. G. 2005. Aquifer Storage Recovery: A Guide to Groundwater Recharge Through Wells. Gainesville, FL: ASR Press. Rinck-Pfeiffer, S., S. Ragusa, P. Sztajnbok, and T. Vandevelde. 2000. Interrelationships between biological, chemical, and physical processes as an analog to clogging in aquifer storage and recovery (ASR) wells. Water Research 34(7): 2110-2118. Ruetten, J. 2001. Best Practices for Developing Indirect Potable Reuse Projects: Phase 1 Report. Product Number 01-004-01. Alexandria, VA: WateReuse Foundation. Ryan, J. N., M. Elimelech, R. A. Ard, R. W. Harvey, and P. R. Johnson . 1999. Bacteriophage PRD1 and silica colloid transport and recovery in an iron oxide-coated sand aquifer. Environ Sci. Technol 33(1):63-73. Schlenk, D., D. E. Hinton, and G. Woodside. 2007. Online Methods for Evaluating the Safety of Reclaimed Water. Water Environment Research Foundation Report No. 01-HHE-4A. Alexandria, VA: Water Environment Research Foundation.
OCR for page 268
Prospects for Managed Underground Storage Recoverable Water Seerley, D. J. W. 2003. An analysis of the evolution of public policy for aquifer storage and recovery: Experiences in three southeastern states. Ph.D. dissertation.The University of Georgia, Athens, GA. Segalen, A.-S., P. Pavelic, and P. Dillon. 2005. Review of Drilling, Completion, and Remediation Methods for ASR Wells in Unconsolidated Aquifers. Technical Report No. 04/05. Canberra, Australia: CSIRO Land and Water. Shrier, C. 2002. Survey and Analysis of Aquifer Storage and Recovery (ASR) Systems and Associated Regulatory Programs in the United States. Denver, CO: American Water Works Association. Swierc, J., D. Page, J. Van Leeuwen, and P. Dillon. 2005. Preliminary Hazard Analysis and Critical Control Points Plan (HACCP) - Salisbury Stormwater to Drinking Water Aquifer Storage Transfer and Recovery (ASTR)Project: CSIRO Land and water Techical Report No. 20/05. Available online at http://www.clw.csiro.au/publications/technical2005/tr20-05.pdf. Accessed November 20, 2007. UNESCO (United Nations Educational, Scientific and Cultural Organization). 2006. Recharge Systems for Protecting and Enhancing Groundwater Resources. Proceedings of the 5th International Symposium on Management of Aquifer Recharge (ISMAR5), Berlin, Germany, 11–16 June 2005. IHP-VI, Series on Groundwater No. 13. Paris: UNESCO. Stuyfzand. P. J. 2002. Modeling the accumulation rate and chemical composition of clogging sludge layers in recharge basins with Easy-Leacher® 4.6. Pp. 221-224 In Dillon, P. (ed.) Management of Aquifer Recharge for Sustainability, Rotterdam, Netherlands: A.A.Balkema. Water Environment Federation and American Water Works Association. 1998. Using Reclaimed Water to Augment Potable Water Resources. Special Publication. Alexandria, VA:Water Environment Federation. WateReuse Foundation. 2004. Best Practices for Developing Indirect Potable Reuse Projects: Phase 1 Report. Report of Project WRF-01-004. Alexandria, VA: WateReuse Foundation. Wildermuth, R. October 2001. Groundwater replenishment system: Public outreach and education program. Presentation at the NWRI National Urban Watersheds Conference, Costa Mesa, Calif., October 17-19.