OPTIMIZED REGIONAL OPERATIONS PLAN ANNUAL REPORT FOR WATER YEAR 2001 SUBMITTED JULY 2002

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2 OPTIMIZED REGIONAL OPERATIONS PLAN ANNUAL REPORT FOR WATER YEAR 2001 SUBMITTED JULY 2002

3 OPTIMIZED REGIONAL OPERATIONS PLAN ANNUAL REPORT FOR WATER YEAR 2001 TABLE OF CONTENTS Page Number EXECUTIVE SUMMARY...v REPORT SUMMARY...vii 1. INTRODUCTION...1 A. General Description...2 B. Consolidated Water Use Permit Conditions...8 C. Goals and Objectives...11 D. Annual Reporting Submittals and Approvals...11 E. Description of Facilities Under the OROP REVIEW OF WATER YEAR A. Wellfield Production and Water Demands...15 B. Forecasted and Actual Production and Demands...16 C. Hydrologic Conditions...18 D. Control Point Correlation Update...24 E. Optimization Plan Improvements...24 F. New Online Regional Water Resources...26 G. Facility Modifications...26 H. Summary of Work Plan Activities WATER YEAR 2002 PROJECTIONS AND PROPOSED ACTIVITIES...29 A. Water Demand Projections...29 B. Proposed Changes to the Optimization Plan...30 C. Planned Outages...37 D. Proposed Facility Changes...37 i

4 4. SUMMARY/CONCLUSIONS...38 A. Summary...38 B. Conclusions REFERENCES...43 LIST of FIGURES...iii LIST of TABLES...iv APPENDICES APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G APPENDIX H APPENDIX I APPENDIX J APPENDIX K OROP Input Data and Output Files Optimization Formulation and Updates Water Level Hydrographs of Regulatory Wells Water Level Hydrographs of OROP Monitoring Wells Comparison of Forecasted, Actual and Historical Well Production Correlation/Regression Analyses for OROP Control Points July 2001 Work Plan Update July 2002 Work Plan July 2003 Report Outline Surface Water Salinity Controls In Support Of Tampa Bay Water s Optimized Regional Operations Plan Eldridge Wilde Wellfield Water Quality Study ii

5 LIST of FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Existing and Proposed Wellfields Under the OROP OROP Monitoring Wells Water Demand Planning Areas Updated Optimization Model Schematic Historical Versus Water Year 2000 and Water Year 2001 Monthly Demand for the Consolidated Permit Wellfields Comparison of Actual and Projected Weekly Demands for each Point of Connection Comparison of Actual and Projected Weekly Wellfield Production Difference in OROP Projected and Actual Wellfield Production and Demands for Water Year 2001 Figure 9 Operating Rule Curves used in Water Year 2001 Figure 10 Figure 11 Water Years Cumulative Rainfall and Deviation from Normal Water Year 2001 Rainfall at Select Stations iii

6 LIST of TABLES Table 1 Table 2 Table 3 Descriptive Summary of Wellfields Descriptive Summary of Existing Major Pipelines Connected to the Regional System Changes to the Facilities Quantity Table Table 4 Facilities Monthly Production Water Year 2001 Table 5 Facilities Monthly Production Water Year 2000 Table 6 Table 7 Table 8 Water Years Actual vs. Water Year 2002 Expected Demands Difference in OROP Projected Demands and Actual Demands at Points of Connection Difference in OROP Projected Production and Actual Production for Each Wellfield Table 9 Summary of Rule Curve Adjustments for Water Year 2001 Table 10 Table 11 Table 12 Table 13 Annual Average Chloride and Sulfate Concentrations by Wellfield OROP Control Points Water Year 2002 Projected and Actual Monthly Production from the Consolidated Permit Wellfields Member Governments Groundwater Demand Projections iv

7 EXECUTIVE SUMMARY The Optimized Regional Operations Plan (OROP) supports Tampa Bay Water s mission to develop water sources while protecting the environment. This customized computer tool uses water table conditions and rainfall data to determine how to rotate production among groundwater supplies to meet demands in an environmentally sound manner. The OROP was developed to enhance Tampa Bay Waters ability to operate its facilities in a manner that allows for flexibility while meeting its environmental stewardship obligations. The program continues to be evaluated, updated, and re-optimized to maximize its operational effectiveness. The OROP meets the requirements of (a) the Amended and Restated Interlocal Agreement (Interlocal Agreement) between Tampa Bay Water Member Governments; (b) the Partnership Agreement between Tampa Bay Water, its Member Governments, and SWFWMD; and (c) the Consolidated Water Use Permit for the 11 Northern Tampa Bay Wellfields. It is considered a primary environmental permit, as identified in the Interlocal Agreement, and is arbitrable annually. In Water Year 2001, a number of enhancements helped improve the OROP s performance, including modified individual wellfield production limits, new control points, and modification of existing monitor wells. Although the extended drought that began in 1999 did continued and surface water availability was limited during Water Year 2001, groundwater production from the 11 Northern Tampa Bay Wellfields declined 2 percent from Water Year 2000 levels. This was due to increased operational flexibility provided through additional conservation efforts, the City of Tampa beginning operation of their Aquifer Storage and Recovery system, and greater rainfall than the previous two years. Operational flexibility was also enhanced through modification of individual wellfield production limits that allowed production to meet demand without violating permit-related constraints. Water levels at the OROP control points recovered significantly following a return to normal summer rainfall in spite of the 3-inch increase in the regional three-year rainfall deficit to 30 inches. This also improved operational flexibility for rotating production. Forecasted production was markedly different than actual production due to significant changes in water supply from the Hillsborough River and short-term changes in demand, driven by changes in local weather. To deal with variability in forecasted versus actual production, Tampa Bay Water began developing a short-term forecasting tool that will improve its capability to forecast based on recent weather effects. This tool will be operational in Spring Minimizing the effects groundwater production has on the surficial aquifer and environmental systems is a primary goal of the OROP. The result of evaluating the OROP s effectiveness in meeting this goal indicates that this program is successful in rotating production away from areas where wellfield pumpage strongly affects surficial aquifer water levels which indirectly affect environmental systems. In response, two control points in the Cypress Creek Wellfield were replaced to improve control of production based on surficial aquifer water levels. In addition, a new surficial control point was added to the Cosme Odessa Wellfield and two control points for the Brandon Urban Dispersed wellfield, which is online and will function as part of the OROP. Beginning in Water Year 2001, annual wellfield environmental assessment report results were coordinated with optimized well production schedules. Six wetland monitoring sites were placed v

8 into an optimization program referral list due to possible production-related water level changes. If these sites remain on the list for one more reporting period, control point target levels will be refined or new control points will be developed to enhance the OROP s ability to measure environmental change. As in previous years, responsiveness of wellfield rotation to regional environmental concerns continues to be constrained due to limitations of the current interconnected system. Tampa Bay Water developed a drought mitigation plan, which was approved by the Board of Directors in December 2001 to identify and simplify actions to proactively ensure water supplies during water shortage periods. This program will allow Tampa Bay Water and its Member Governments to coordinate demand management efforts with water shortages, thereby increasing the effectiveness of the OROP. vi

9 REPORT SUMMARY This report contains the following information: a review of the information submitted in the revised OROP of October 1998; an operational summary of the 11 wellfields under the Consolidated Permit during Water Year 2001 (October 1, 2000 through September 30, 2001); descriptive information concerning hydrologic conditions during Water Year 2001; changes to the Optimization Plan that were implemented during Water Year 2001; and, changes to the Optimization Plan proposed for Water Year The Optimization Plan utilizes an integrated hydrologic simulation model and an optimization model to manage the 11 wellfields under the Consolidated Permit as an integrated regional water supply system through the development of an optimized production schedule every two weeks. The hydrologic model, which is based on the physical characteristics of the surface and ground water system, simulates changes in water levels due to changes in pumpage and rainfall. The optimization model schedules production from the wellfields, based on current hydrologic conditions, in order to meet Member Government demands and seeks to maintain ground-water levels as high as possible at a selected set of surficial aquifer monitoring wells called control points (this is based on the hydrologic model providing a unit response for each production/monitor well combination which relates pumpage changes to water-level changes). The output of the simulation/optimization modeling is a bi-weekly schedule prioritizing pumpage from the production wells. The objectives of the Optimization Plan are to (a) improve Tampa Bay Water's ability to understand the water-level effects of wellfield operations that impact environmental conditions, (b) enhance wellfield management programs to benefit the surrounding environment, and (c) increase water levels in areas of interest while meeting Member Government water demands Work Plan activities and changes to the OROP that were implemented during this reporting period are summarized below: Received Board approval of changes to the Facility Quantity Table specifying wellfield production limits. Completed the scientific peer review of the Integrated Surface and Ground Water model (ISGW) and used results to guide scope development for the revisions and enhancements to the ISGW. Completed Phase II of the Hydrologic Model Uncertainty Analysis project and used results to guide scope development for the revisions and enhancements to the ISGW model. Initiated enhancements and revisions to the ISGW model. Initiated the Decision Support System Phase I project. Updated control point regression/correlation analyses to include Water Year 2001 data. Substituted two existing control points in the Cypress Creek Wellfield with replacement controls point wells (TMR1as and TB-22as) and revised H l values (low water level set point). vii

10 Completed the Phase I testing program at the Cosme-Odessa Wellfield and after data evaluation selected a new control point (COS 20s) for inclusion into the OROP to improve well rotation priorities for the southern portion of the Cosme-Odessa Wellfield; continue monitoring the effects of the pumping distribution based on the OROP. Initiated development of a short-term demand forecasting model that is expected to be operational by Spring Initiated development of a long-term demand forecasting system that is anticipated to be completed by the end of Water Year Continued development of a GIS-based procedure to analyze whether or not new or replacement control points are needed. Completed Phase I Eldridge-Wilde Wellfield Water Quality evaluation which confirmed water quality concerns associated with production wells. Implemented the interaction protocol between the Environmental Management Plan (EMP) and OROP. The 2001 Work Plan has been revised and updated to become the 2002 Work Plan. Completed tasks were removed from the work plan and new tasks were identified and added as part of the ongoing implementation of the OROP. As Work Plan tasks are completed, following a period of review by the OROP Technical Advisory Committee (OROP TAC or TAC) and approval by the District, results which lead to improvements and refinements will be incorporated into the OROP as part of continuous implementation of the program. Tampa Bay Water staff (staff) will report these results or refinements to the Board as part of the OROP annual update report required by the Consolidated Permit. Summary of Hydrologic Conditions and Water Production Although the extended drought resulted in limited surface water availability and above average water demand in Water Year 2001, groundwater production decreased as compared to Water Year This was due to increased operational flexibility resulting from the City of Tampa s Aquifer Storage and Recovery activities, conservation efforts, and greater rainfall than in the previous Water Year. Production from the 11 wellfields in Water Year 2001 was approximately 2% lower than production experienced during Water Year 2000 and only 2% higher than production experienced during Water Year Rainfall in Water Year 2001 was approximately 14% lower than expected rainfall for this region but was higher that the Water Year 2000 rainfall totals. The rainfall deficit which began in Water Year 1999 was 29.5 inches at the end of Water Year 2000 for the 11 wellfield areas and increased to 36.6 inches by the end of Water Year Regionally, the rainfall deficit from Water Year 1999 through 2001 (3 years) increased to 30 inches; a net increase of only 3 inches. Operational data for the 11 wellfields under the OROP were evaluated for Water Year Forecasted demands and wellfield production were compared against actual demands and production from October 1, 2000 through September 30, A summary of the results indicates that the largest differences between forecasted and actual production occurred at the Cross Bar Ranch, Cypress Creek, and Morris Bridge Wellfields. viii

11 The primary reason for the differences between actual and forecasted production from the 11 wellfields was the increased groundwater production necessary to meet the City of Tampa s demands. Beginning in mid-february 2000 and continuing through March 2001, flows in the Hillsborough River were significantly lower than average due to drought conditions; this necessitated an increase in groundwater production. However, actual regional groundwater demands for April and May 2001 were below forecasted groundwater demands due to increased water use restrictions and activation of the City of Tampa s Aquifer Storage and Recovery System (ASR). Tampa Bay Water also initiated a project to develop a short-term demand-forecasting tool to improve our short-term demand forecasting capability and incorporate recent weather effects. It is anticipated that this modeling tool will be operational by Spring Groundwater level hydrographs for the OROP control points are provided for the period of October 1999 through September Water levels at 16 of the 32 control points were below their target levels at the end of Water Year 2001, compared to 20 of the 32 control points below target levels at the end of Water Year While water levels at all of the control points declined during the spring dry season, 25 of the 32 wells exhibited significant recovery with the summer rainy season. There were three monitor wells that continued dry throughout Water Year 2001 (two in the Cypress Creek Wellfield and one in the South Pasco Wellfields). Tampa Bay Water conducted an assessment of the effectiveness of the existing surficial aquifer control points in rotating production away from areas where wellfield pumpage strongly affects surficial aquifer water levels. Preliminary analysis indicates that most of the existing control points are effective in moving production away from areas with chronic low water levels realizing our current operational constraints. This evaluation will be reassessed in 2003 after new water sources have been added to our regional system to further evaluate control point effectiveness. The existing and proposed work efforts are detailed in Appendix B. Two new control points (TMR1as and TB-22s in the Cypress Creek Wellfield were added to the OROP routine in Water Year It is anticipated that the addition of these control points will improve the OROP program effectiveness. The Cosme-Odessa Wellfield phase I testing program was conducted during this reporting period. Based upon results of this effort an additional control point (COS 20s) was added at the south end of the Cosme-Odessa Wellfield to ensure adequate protection of the surficial aquifer levels and associated ecosystems. A testing program was initiated in November 2001 to determine how this new control point will affect production distribution within this wellfield while meeting OROP objectives. It is anticipated that COS 20s monitor well will become a permanent control point in Water Year Ground-water level hydrographs for Upper Floridan Aquifer System (UFAS) regulatory wells were also evaluated in this annual report. During Water Year 2001, many UFAS water levels remained about the same or were slightly higher than Water Year 2000 levels. Relative to the time period (which represents a five year period prior to implementation of the OROP), UFAS waterlevel conditions at the end of September 2001 were 4 feet below previous end-of-september water levels in the Cypress Creek Wellfield and only 1.4 feet lower than previous end-of-september water levels in the Cosme-Odessa Wellfield. ix

12 The comprehensive environmental assessments conducted as part of the 11 wellfields annual reporting requirements (Special Condition 13 B. of the Consolidated Permit) and implementation of the OROP/EMP interaction protocol are the mechanisms used to determine if shifts in production due to the OROP are causing unanticipated environmental impacts at any of the 11 wellfields. Water Year 2001 was the first year that OROP/EMP interaction protocol was implemented, and six wetland monitoring sites were referred to OROP based on the spring 2001 reports. (The spring reports are based on review of wetland hydrologic data from the dry season months of October through May.) The six sites consisted of three wetland monitoring sites from the J.B. Starkey Wellfield monitoring program and three sites from the Cypress Creek Wellfield monitoring program. No action is required for the first referral of a wetland to the OROP. The second consecutive referral of a wetland to the OROP requires a site-specific analysis and may result in either the adjustment of a target level or the addition of a new control point. A total of 25 wetland monitoring sites were referred to OROP based on analysis of wet season (June September) data (Table F-3). This was the first referral to OROP for the majority of the sites, but for two of the wetlands, one at Morris Bridge Wellfield and one at the Cypress Creek Wellfield, this was the second consecutive referral. Based on these referrals, Tampa Bay water staff will be analyzing the need for adjustment to target levels at nearby control points and/or at the possibility of adding control points in the vicinity of these wetlands. Comparisons of average chloride and sulfate concentrations for all production wells for Water Years 1998 through 2001 are provided in the report. There are no noteworthy changes in short-term chloride or sulfate concentrations in the production wells based on these annual averages by wellfield. Thirteen production wells at the Eldridge-Wilde Wellfield were taken out of OROP and placed on a Water Quality Deferred List (Tampa Bay Water, 2000) due to water quality concerns. The operational protocol (approved by the District in October 1999) limited production of these 13 wells to times of extreme water demand by Pinellas County. Short-term increases in chloride concentrations were observed in some of these 13 wells during Water Years 2000 and Based on the quarterly water quality monitoring at the Eldridge-Wilde Wellfield, no changes to the water quality deferred list of production wells are recommended. Results of the Phase I Eldridge-Wilde water quality study revealed that a number of the production wells in the southwestern portion of the wellfield have increasing long-term trends in chloride concentrations. All 13 production wells on the Water Quality Deferred List in were confirmed by this study as having water quality problems that are strongly related to well pumpage. In addition, through Tampa Bay Water s production well rehabilitation program and routine monitoring and maintenance, an additional nine production wells (with other technical and/or quality problems) have been removed from the OROP priority rotation schedule. Final deposition of these 22 wells is under evaluation; some will be used for short-term and long-term monitoring and others will be abandoned. In addition two production wells at the Section 21 wellfield (Well #2 since Sept 2000 and well #6 since June 2000) are out of service due to water quality concerns and have been removed from the OROP priority rotation schedule. x

13 No new facilities were added to the OROP during this reporting period. Part of the Brandon Urban Dispersed Wellfield (BUDW7) was brought online in Water Year 2001, but the facility will not be added to the OROP until February 2002 when the remaining four production wells will deliver water to the Regional System. Proposed Changes for Implementation During Water Year 2002 Implement the new control points (BUD FL-14 and BUD FL-21) for the Brandon Urban Dispersed Wells water supply facility and control point set points for these monitor wells. Implement the new control point (COS-20s) for the Cosme-Odessa Wellfield, following approval from the District. Implement revisions to control point set points (i.e., high water level, low water level, and target levels) (Appendix F). Implement revisions to the OROP to include new surface water sources (Tampa Bypass Canal, Hillsborough River, and Alafia River) (Appendix B). Remove 22 production wells at the Eldridge-Wilde Wellfield from the OROP rotation; final disposition of these well is under evaluation. Implement short-term demand forecast model for use in the OROP. Initiate migration of OROP UNIX-based program to Windows-based operating system. Implement the 2002 Work Plan tasks. In conclusion, this annual report covers Water Year 2001 (October 1, 2000 through September 30, 2001). The optimization model is working within certain limitations, as designed. The current formulation of the OROP does not include source water quality as an explicit constraint; however, in recognition of this deficiency an Operational Protocol for the Eldridge-Wilde Wellfield was developed, approved by the District, and implemented in November This protocol removed 13 production wells from the OROP production schedule due to increasing water quality concerns. Results from further evaluations lead to the removal of nine additional Eldridge-Wilde Wellfield production wells from the production rotation. Water quality will continue to be monitored and evaluated as part of the annual comprehensive wellfield monitoring and reporting requirements. The OROP Water Year 2002 Workplan includes tasks for additional water quality evaluation and assessment. While groundwater levels began to recover in Water Year 2001, effects of the extended drought continue across the region. The three year cumulative rainfall deficit (Water Years ) increased to nearly 30 inches. This drought condition caused an increase in groundwater production during Water Year 2000 and early in Water Year 2001 beyond what was contemplated or anticipated when the Consolidated Permit was negotiated. The increased production reduced wellfield rotation xi

14 flexibility in the current interconnected system and limited the ability to produce an optimal production schedule that is fully responsive to regional environmental concerns. Implementation of the City of Tampa s ASR system and increased conservation efforts by all member governments lessened the effect that reduced surface water supply capacity had on regional groundwater production. In December 2001, the Tampa Bay Water Board adopted a Drought Mitigation Plan to identify and simplify actions to proactively ensure water supplies during drought and provide an operational tool to ensure that Tampa Bay Water meets member water demands during water shortage periods. Until additional facilities are brought online and interconnected with the existing OROP based facilities, the OROP model's ability to optimize production to the benefit of stressed environmental conditions will continue to be limited. Developing measures of program effectiveness with respect to identifying improved environmental conditions is included in the 2002 Work Plan. xii

15 OPTIMIZED REGIONAL OPERATIONS PLAN ANNUAL REPORT FOR WATER YEAR INTRODUCTION Under (a) the Amended and Restated Interlocal Agreement between the Tampa Bay Water Member Governments, (b) the Partnership Agreement between Tampa Bay Water, its Member Governments, and the Southwest Florida Water Management District, and (c) the Consolidated Permit for the eleven Northern Tampa Bay wellfields operated by Tampa Bay Water, operation of the 11 wellfields (Figure 1) will be governed by the Optimized Regional Operations Plan approved by Tampa Bay Water s Board of Directors and SWFWMD s Governing Board. When additional production capacity is brought on-line to the Interconnected Regional System, the Optimization Plan is to be modified. Modification of the Optimization Plan to accommodate additional capacity will be necessary in each instance of added capacity, and changes to operations will occur in accordance with conditions of the Interlocal Agreement, the Partnership Agreement, and the Consolidated Permit. At a minimum, submittal to the SWFWMD of Optimization Plan annual updates is required. Following the first submission of the OROP on June 30, 1998, SWFWMD reviewed and provided several comments and questions in letters dated August 28 and September 9, The revised Optimization Plan was resubmitted by Tampa Bay Water on October 30, 1998 and was approved by SWFWMD on November 20, The Optimization Plan went into effect on January 1, 1999 and the first production schedule generated under the Plan was implemented on January 22, Annual reports have been submitted and approved as follows; first annual report submitted July 16, 1999 and approved by the District September 9, 1999, second annual report submitted April 28, 2000 and approved by the District June 14, 2000, and the third annual report submitted May 8, 2001 and approved by the District June 20, Copies of the Revised OROP report (1998), and the Water Year 1999, 2000 and 2001 annual reports are available in the Records Department of Tampa Bay Water. The OROP is considered a Primary Environmental Permit as defined in the Amended and Restated Interlocal Agreement. Due to the time constraints defined in the arbitration process associated with Primary Environmental Permits, staff has developed a report preparation schedule that will allow Board approval of the final annual report each year by the March Board meeting. This is intended to provide adequate time to comply with the arbitration provisions of Section 3.13 of the Amended and Restated Interlocal Agreement prior to submittal of the annual report to SWFWMD by July 1 of each year. This fourth annual report contains a review of the information submitted in the revised OROP (October 30, 1998), information regarding operation under the Optimization Plan for Water Year 2001, descriptive information concerning hydrologic conditions during Water Year 2001, changes to the Optimization Plan that were implemented during Water Year 2001, and changes to the Optimization Plan proposed for Water Year

16 A. General Description The Optimization Plan utilizes an integrated hydrologic simulation model and an optimization model to manage the 11 wellfields under the Consolidated Permit as an integrated regional water supply system through the development of an optimized production schedule every two weeks. The hydrologic model, which is based on the physical characteristics of the surface and ground water system, simulates changes in water levels due to changes in pumpage and rainfall. The optimization model schedules production from the wellfields, based on current hydrologic conditions, in order to meet Member Government demands and seeks to maintain ground-water levels as high as possible at a selected set of surficial aquifer monitoring wells called control points (this is based on the hydrologic model providing a unit response for each production/monitor well combination which relates pumpage changes to water-level changes). The output of the simulation/optimization modeling is a bi-weekly schedule prioritizing pumpage from all active production wells. The optimization model is solved using MINOS version 5.5, a linear/nonlinear programming (LP/NLP) package based on the primal simplex method written in FORTRAN programming language. The program was installed on a SUN UltraSPARC 60 running the Solaris-8 operating system. The program was compiled and linked into an application using the SUN Performance Workshop FORTRAN compiler. Like most commercial optimizers, MINOS requires two data input files, the SPECS-file for setting run-time parameters that describe the nature of the problem, and the Mathematical Programming Systems (MPS) file for naming and defining variables and constraints. The term MPS was initiated by IBM during its development of linear programming software. Practical Extraction and Report Language (PERL) scripts were written to help automate the process of generating bi-weekly production schedules. The scripts' functions include retrieving data from the database, preparing the input files, launching the application, generating production schedule reports from the output files, creating the production schedule Web pages, and sending out reports to the water treatment operators via Tampa Bay Water's intranet system. The scripts prepare the optimizer's input files from the constraint tables and simulated water levels are saved in various formats including ASCII, FORTRAN binary, and ORACLE database. The Integrated Surface/Ground Water model referred to as ISGW/CNTB 121 is used to simulate water levels each time the production schedule is forecasted. The model was developed by SDI Environmental Services, Inc. for Tampa Bay Water (SDI Environmental Services, 1999). This model is currently being revised and enhanced as a result of the scientific review and uncertainty analysis projects. The mathematical formulation for the optimization routine was described in the revised OROP report (October 30, 1998) and is provided in Appendix B. Several revisions and improvements have been implemented since the October 30, 1998 report; the nonlinear optimizer was replaced with a linear optimizer, the use of a penalty function to relate Floridan Aquifer regulatory water levels and pumpage was revised to include the regulatory water-levels in the optimization routine as linear constraints which simplified the objective function, the use of actual Upper Floridan Aquifer waterlevel data in the optimization routine instead of simulated water levels, and implementation of the new unit response matrix (URM) generated from ISGW/CNTB Model 121. These revisions are discussed in Appendix B. 2

17 (1) Constraint and Control Points The optimization model seeks to maximize ground-water levels at a select set of surficial aquifer monitoring sites called control points while meeting projected demands at 11 Member Government delivery points. It also adheres to operating policies and infrastructure physical limits as well as complies with the Consolidated Permit conditions. Infrastructure limits and permit conditions are reflected in the optimization model through the constraints. Policy issues are addressed by the use of weight values to assign preferences to maximize ground-water levels at specific control point locations. The non-linear weighting function causes the program to search for an optimal solution which preferentially reduces drawdown, thereby increasing water levels at locations with higher weights. The numerical values associated with the following constraints are listed in Appendix A. The constraints applied in the optimization analysis include: maximum production by well, which is either the permitted peak month well production limit or maximum well production capacity based on physical limits; maximum long-term production rate by wellfield (36-month running average permitted limit); wellfield peak monthly production limits that were developed by Tampa Bay Water staff using the following methods: previously permitted peak month quantities, requested peak month quantities by Tampa Bay Water through the water use permitting process, or historical maximum four-week running average, where applicable; maximum weekly production rates by wellfield given in mgd (based on historical seven-day average pumping for the most recent six-year period from Water Year 1994 through Water Year 2000); minimum production rates by wellfield (based on minimum operational limits for satisfactory operation of meters, treatment systems, and other system components [expressed in mgd] or 10 percent of the permitted average wellfield production, whichever is greater); water levels at specified Floridan Aquifer regulatory wells (listed by prior permits with the addition of two wells for saltwater intrusion control); transmission and treatment system constraints concerning rates and directions of flow in the network; and, demand at Points of Connection with Member Government systems. An additional set of constraints that represent the integrated surface/ground water hydrologic system is required to complete the optimization formulation. This set of constraints is a system of transfer function values that relate pumpage increments to water level responses through the unit response matrix (URM) generated using the ISGW/CNTB model. 3

18 Control Points Tampa Bay Water staff developed an approach that measures the current water level at specified control points (surficial aquifer monitoring wells) and compares the measured levels against target water levels to generate weighting factors. The weighting factors assign preference for reducing pumping in environmentally stressed areas and increasing pumping in areas with higher water levels. Observed water levels at these sites serve as surrogates for wetland and lake water level conditions. Without knowledge of prevailing hydrologic conditions, weighting factors would be set equal at all control points. However, current water level conditions at each control site are updated bi-weekly; thus, the weighting factors are also updated every two weeks. These weighting factors then force the optimized production solution to reduce pumping at locations where observed water levels are substantially below specified target levels and to increase pumping where observed conditions are relatively more favorable. The selection criteria and list of the original 31 control sites for the surficial aquifer system are described in Appendix C of the Revised OROP document (October 30, 1998). Historical data were used to perform correlation analyses and to develop regression relationships that formed the basis for the weighting function at each site. Discussions in Appendix D of the Revised OROP document (October 30, 1998) include the development of target levels from the correlation and regression analyses (based on mean ground-water values and wetland/lake Minimum Levels) and application of the weighting function (based on actual recent data and the historical high/low range of data). Since implementation of the OROP in January 1999, changes have been made to the original set of 31 control points. These changes are documented in the Water Year 1999, 2000, and 2001 OROP annual reports. Currently, there are 33 SAS and 2 UFAS monitor wells which are used as control points in the optimization routine (see Figure 2). (2) Optimized Production Schedules The optimized production schedules are developed every two weeks. The first schedule was developed for the production period beginning January 22, Initially, the production schedule ran from Friday until the following Thursday. Beginning on August 28, 1999, the weekly schedule was changed at the request of Tampa Bay Water's operators so that the production week begins on Saturday and runs through the following Friday. Several pieces of information must be available every two weeks to produce the optimized production schedule. First, a short-term (four-week) ISGW simulation is completed which generates initial upper Floridan Aquifer water levels and wellfield pumpage for the optimization model. Observed water-level data are not used as the starting points for the short-term optimization analysis, because the hydrologic simulations using the ISGW model require at least one year of simulation time to reach numeric equilibrium. Therefore, for consistency, the simulated heads (specifically at regulatory wells) are used to start the optimization model and to determine constraint values. Wellfield pumpage from the ISGW model is used as initial values to start the optimization search procedure. The short-term ISGW simulation uses the most recent production and rainfall data available. When actual data are not available, projected values are used. 4

19 Second, water level data at the control site monitoring wells are obtained every two weeks at more or less regular time intervals, and the water-level database is updated upon receipt of observed data. The optimization routine accesses the water-level database and extracts the most recent data for each control site and computes the weighting factors. The observed water levels are used as reference levels to calculate new water level responses as the pumpage is iteratively adjusted toward the optimum by the optimization model. The calculation of new water-level conditions is based on the unit response matrix explicitly pre-generated using the same version of the ISGW model. Third, water demand forecasts for the next four-week period are made for the 11 delivery points which serve the Member Governments. Fourth, a check is made to determine which production wells will be out of service during the next two-week period. The optimization routine is updated to remove from the rotation schedule those wells which will be out of service due to maintenance, mechanical, or water quality reasons. The optimization routine accesses this information automatically and updates the program with the new data. Once all of the input data updates are completed, the optimization program automatically runs at a pre-determined time, producing a schedule of production rates for each active well for each wellfield and a well rotation priority for all active wells; the schedule is automatically transmitted to the operators. The four-week optimization analysis adjusts the pumping distribution by week (changing pumping rates incrementally from the base case) to meet the projected short-term demand. The model achieves an optimal distribution so that the water-level increase compared to the base run is maximized in the global sense (space and time, all control point locations and all weeks). Lower and Upper Rule Curves for each wellfield facility are also used by the optimization program to ensure that overproduction of each wellfield with respect to its 36-month running average does not occur during the short-term (four-week) operations projections. Currently, the rule curves are generated from a long-term (52-week) ISGW/CNTB simulation. The 52-week simulation distributes pumpage temporally, anticipating seasonal variations so that overproduction from wellfields on the early four-week time-scale is avoided. This simulation is reanalyzed on a seasonal basis (quarterly) to account for updated data needed to reflect hydrologic changes in the long term. (3) Demand Forecasts (Methodology) Tampa Bay Water's tri-county service area is disaggregated into eight "Demand Planning Areas". The planning areas are shown in Figure 3. Some demand planning areas, like Northwest Hillsborough County, are served by multiple facilities through the interconnected regional system. Other demand planning areas, like West Pasco County and East-central Pasco County, are served primarily by isolated facilities such as the Starkey and North Pasco Wellfields, but also receive some water at various connection points from the interconnected regional system (i.e., Pasco interties and Lake Bridge WTP). Seven of these water demand planning areas receive water from some or all of the 11 wellfields under the Consolidated Permit. Currently, the South-Central Hillsborough water demand planning area does not receive any water from facilities controlled by the OROP. Pasco County water demand projections completed by Ayres Associates for Tampa Bay Water combined the West Pasco and East-central Pasco water demand planning areas into one demand planning area; therefore, the remaining seven demand planning areas were reduced to six for purposes of discussing demand projections in this report. 5

20 Within the six demand planning areas under the Consolidated Permit, there are 11 points of connection (water delivery points) for which short-term and long-term demand projections are developed for the Optimization model; Keller influent, Little Road influent, Maytum influent, Morris Bridge influent, Lake Bridge influent, Cosme influent, Northwest Hillsborough influent, Lake Park influent, Pinellas Distribution, and two Pasco Interties. Due to the configuration of the interconnected wellfield system, certain wellfields are available to meet demands at certain demand points. A schematic of how water-flow is modeled through the optimization routine is shown in Figure 4; note, however, that this diagram is not intended to accurately depict the complete pipeline and wellfield infrastructure. The optimization routine determines the projected wellfield and well production schedule based on the water demands projected for each of the points of connection. Long-term Demand Forecasting Tampa Bay Water uses three levels of demand forecasting in planning for and managing its water supply facilities; long-term (annual), monthly, and near-term (two weeks). The current long-term demand forecasting methodologies used by Tampa Bay Water do not reflect the inherent uncertainties in long-term projection data such as seasonality, abnormal weather patterns, or population projections. A long-term demand forecasting system (DFS) that defines, estimates, and portrays these uncertainties and others is being developed to increase the information available to decision makers that would allow them to better plan the capacity and construction sequencing of future water supply projects to optimize cost effectiveness. The goal of the long-term demand forecasting system (DFS) is to develop an integrated, easily updated system for Tampa Bay Water to forecast future water demands and to understand the uncertainty associated with these forecasts. To enable its use for minimizing the rate impacts of future water supply projects in Configuration II/III, the DFS must be completed under an extremely tight timetable. Yearly forecasts by Member Governments must be available for the Tampa Bay Water budgeting process by June 2002 and preliminary probabilistic forecasts to further define the next set of water supply projects is set for construction sequencing in September The objective of the DFS project is to develop a forecasting system that meets the above goal as well as provides Tampa Bay Water with the needed data under this short timetable. Components of the proposed system include: The ability to evaluate input and water use data spatially A system to easily develop long-term water demand forecasts by monthly time steps The output of risk-based, probabilistic water demand projections, which can then be used to estimate the timing and reliability of future supplies. The system will include a GIS-based application for querying the spatial database, and generating adhoc water demand projections, maps, and reports. Yearly updates in population and water use databases provided by member governments will allow increased accuracy in forecasting long-term water supply demand. These long-range projections, while used primarily for water supply planning purposes, are also used in developing annual demand projections for the OROP and will be used beginning in

21 Monthly Demand Forecasting Monthly demand projections for each of the water demand planning areas and the 11 points of connections used in the Optimization routine are developed by Tampa Bay Water based on historic use patterns and the projected average annual demands described above. The Member Governments do not project their monthly water demands. Also, staff classifies the demand which will be satisfied by pumpage from wellfields under the Consolidated Permit into three groups: Starkey/North Pasco, nine interconnected regional facilities, and the City of Tampa to facilitate projecting the monthly demands for the 11 delivery points. Historic data from Water Year 1990 through Water Year 1999 were used to develop monthly use coefficients which were then used to convert the annual average demands for each point of connection into monthly expected demands. For each Water Year, a monthly total production rate for the 11 wellfields under the Consolidated Permit is also projected by staff based on expected demands; this projected production rate is revised during the Water Year to reflect changing demand estimates and weather forecasts. Near-term Demand Forecasting Near-term demands are forecasted every two weeks for the Optimization routine. The focus of the near-term demand projections is to supply information to the optimization program such that a well and wellfield production schedule can be developed which meets the expected near-term water needs. Near-term projections do not include adjustments in water demand based on growth factors because this information is not available. Near-term demand projections are generated by Tampa Bay Water because the Member Governments do not forecast demands on a two-week basis. Staff develops near-term demand forecasts for each of the 11 points of connection, which are updated every two weeks, based on: historic seasonal water demand patterns, information on the capacity of relatively recent interconnections or modifications to the transmission capacity of interconnections at certain points in the system (e.g., recent installation of booster facilities at Pasco County Interties on the 84-inch transmission main), recent demand information from the past two to four weeks, current and projected rainfall and temperatures (30 to 90 day predictions from NOAA), and operational constraints such as planned infrastructure improvements or well maintenance. The current two-week demand forecast procedure does not include the use of a statistical forecasting tool; therefore, the effects of changes in temperature and rainfall on demand projections are not explicitly included in the demand forecast. Subjectively, based on professional experience and opinion, staff modifies short-term projections based on weather predictions received from NOAA. Inevitably, actual demands and actual production will vary somewhat from forecasted rates. As near-term demand projections are adjusted, monthly demand projections are also adjusted to reflect anticipated monthly, quarterly, and annual changes resulting from modifications in service areas (such as new development), persistent seasonal weather patterns (e.g., a prior six-month period of abnormally warm dry weather), and newly scheduled capital improvements to treatment and/or conveyance facilities. 7

22 Short-term Demand Forecasting Model Tampa Bay Water initiated a project during Water Year 2001 to develop a short-term demand forecast model which will allow near-term demand forecast which incorporate near-term weather patterns. The model is nearly complete and is expected to be operational by May Following implementation of this model, the effects of near-term weather patterns on short-term demand forecasts will be assessed. B. Consolidated Water Use Permit Condition Special Condition 4.A of the Consolidated Permit requires that the Optimization Plan address or comply with nine listed items. Interpretations of and compliance with these requirements as they relate to the revised Optimization Plan were provided to the SWFWMD in the October 1998 submittal. This annual report summarizes and, where appropriate, revises the explanation of compliance with these requirements. (1) Define and control how the Permittee will operate the Central System. The Optimization Plan defines the process and procedures by which Tampa Bay Water operates the 11 listed wellfields (Cosme-Odessa, Cross Bar Ranch, Cypress Bridge, Cypress Creek, Eldridge- Wilde, Morris Bridge, North Pasco, Northwest Hillsborough, Section 21, South Pasco, and Starkey). Since January 22, 1999, the operation of these wellfields with regard to production rates and schedules has been controlled by the Optimization Plan, which is comprised of a hydrologic simulation model, an optimization routine (expressed through mathematical equations), and their associated data and constraint specifications. (2) Provide the protocol under which the Permittee will select among available interconnected supply sources to meet demand. Every two weeks, all production wells not out of service for maintenance or otherwise limited in availability and all sources that can contribute to meeting demand at each Point of Connection are listed. Minimum run-time requirements to maintain well clearance standards and minimum wellfield production rates for metering and line maintenance for the forecast period of four weeks are specified. The optimization algorithms are applied to determine individual weekly-averaged well production rates for the forecast period in a two-step process. The first step uses a long-term base scenario of 52 weeks based on average hydrologic conditions and demand, and develops a rule curve using plus/minus one standard deviation of the average historic demand for the six-year period The 52-week base scenario is intended to capture monthly and seasonal variability in both projected demand and anticipated rainfall conditions, and it establishes an anticipated rotational schedule to occur within the bounds of the rule curve. The second step is a short-term analysis of four weeks which accounts for the prevailing environmental conditions and near-term demand forecasts. Operations and Facilities Management staff operate wells on a daily and hourly basis in a manner intended to meet the weekly limits specified by the optimized solution of individual well rates, allowing for variations in actual demand from projections and short-term (less than two weeks) maintenance activities. 8