This report updates the Comprehensive Water System Plan (WSP) developed in 1991 for the Lakehaven Utility District (District). The WSP's purpose is to schedule the orderly development of District programs and facilities. Principal objectives of this update are as follows:

• Describe the existing system, establish future service area boundaries, and summarize service area policies (see Chapter 1.0).
• Forecast demographic growth for single-family residents, multi-family residents, and employment (see Chapter 2.0).
• Summarize how planning efforts of the South King County Regional Water Association, Pierce County, and other purveyors relate to this plan update (see Chapter 3.0).
• Forecast water demand growth while accounting for the effects of demographic growth, conservation, price changes, and climate patterns (see Chapter 4.0).
• Adopt new conservation measures that are cost-effective and either reduce per-capita unit demand or conserve potable water supplies normally consumed for non-potable uses. Indicate the District's progress toward meeting King County's conservation goal for reducing per-capita unit demand (see Chapter 5.0).
• Adopt new water reuse measures that are cost-effective and either conserve potable water supplies normally consumed for non-potable uses or augment the District's groundwater supplies (see Chapter 6.0).
• Characterize the need for new water supplies and schedule supply acquisition to meet the District's future average-day and maximum-day water demand (see Chapter 7.0).
• Characterize the water system's capabilities during short-term and long-term water demand conditions (i.e., 2003 and 2017, respectively); and develop a plan to provide adequate transmission, distribution, storage, and supply facilities in the service area through 2017 (see Chapters 8.0 and 9.0).
• Assess water quality issues and determine treatment requirements for the District based on existing and anticipated state and federal regulations. Develop a treatment plan for the service area (see Chapter 10.0).
• Develop a six-year capital improvement plan that schedules projects already initiated, new necessary projects, new optional projects, and non-capital revenue requirements. Estimate the six-year revenue requirement for unscheduled projects that may or may not be completed during the next six years. The six-year capital improvement plan includes all projects recommended based on the source of supply, system, and water quality analyses (see Chapter 11.0).
• Characterize the financial condition of the District, assess options for generating revenues; and, evaluate the District's ability to meet the revenue requirements to finance the six-year capital improvement plan (see Chapter 12.0).

This plan is intended to comply with the applicable requirements of the Washington State Department of Health (DOH), King County, City of Federal Way (Federal Way), and other jurisdictions located within the District's water service area. The Washington State Department of Health requires all purveyors with systems that serve more than 1,000 connections to have a WSP approved by DOH, pursuant to Washington Administrative Code (WAC) 246-290-100 and WAC 246-290-140. This WSP must be updated every six years.

The District's water service area is located in the Southwest corner of King County. As of 30 April 1997, the District was servicing a residential population of approximately 97,000 through 25,667 total connections. The water system includes approximately 450 miles of water mains, 20 active wells, and 12 storage tanks. The average daily water use is about 10.6 million gallons per day (MGD). Customers are primarily supplied with groundwater from the District's four major aquifer systems. Since 1991, the District has been buying surface water from Tacoma Public Utilities (Tacoma) to supplement and conserve groundwater supplies. The future service area for the District is shown in Figure 1-3.

Demographic forecasts are basic planning elements because they determine water demand growth in the District. The expected rate of water demand growth determines when additional facilities will be required and what capacity will be necessary.

Demographic forecasts were developed for both population and employment. Development of these forecasts is discussed in Chapter 2.0. The forecasts were developed based on the most recently adopted land use plans and policies of municipalities and counties located within the District's water service area.

Demographic forecasts were projected through 2017 for two scenarios. Scenario One is based on the most recently adopted land use plans and policies of local municipalities and counties. Scenario Two is similar to Scenario One except that it assumes a less aggressive growth rate for employment. The 2017 forecast under Scenario Two projects approximately 18,000 fewer employees than the Scenario One forecast. Table ES-1 summarizes the population and employment forecasts for both scenarios.

Consideration was given to both forecasting scenarios. Scenario One was selected for subsequent planning purposes in an effort to be consistent with the land use planning and policies of affected jurisdictions, despite the possibility that the employment forecast may be too aggressive.

The District's Comprehensive Water System Plan has been updated to be consistent with related coordinated water system plans and individual water system plans of neighboring utilities. The major relationships between related plans and the District's planning efforts are discussed in Chapter 3.0.

Water demand forecasts are used to determine the timing and amount of future supply and facility needs. Forecasts were developed for average-day demand (ADD) and maximum-day demand (MDD) through 2017. Separate sets of forecasts were developed with and without implementation of the recommended new conservation measures discussed in Chapter 5.0. Tables 4-3 through 4-10 show water demand forecasts in aggregate form, disaggregated according to short-term versus long-term planning horizons, disaggregated according to pressure zone group, and in terms of Equivalent Residential Units. Table ES-2 shows the water demand forecast used for planning purposes.

Notes:
(a) 1997 actual ADD was 10.2 MGD
(b) 1997 actual MDD was 21.2 MGD; 1998 actual MDD was 22.1 MGD

The water demand forecast used for planning includes the water savings from implementing the new conservation measures recommended in Chapter 5.0 and uses single- and multi-family unit-demands that could be expected during drought conditions in summer months. Maximum-day water demand projections are based on an annual MDD-to-ADD peaking factor that is estimated to be 2.34 through 2003 and is expected to decrease to approximately 2.14 by 2017.

Appendix B shows the methodology and analysis of single-family and multi-family unit demand in the District. More forecasting detail was given to the single-family residential and apartment/mobile home billing classes because they have historically accounted for more than 80 percent of the District's consumption. Econometric models were developed for single- and multi-family unit demand to predict unit-consumption based on the effects of climate, weather, water price change, and conservation education. Simpler, trend-based projection methods were used for the commercial, irrigation, sprinkler/fire, and public authority billing classes.

Until the time of this planning effort, the District has been achieving conservation goals primarily through consumer education and technical support. In the future, the District plans to implement additional conservation measures that involve distribution of water saving devices and other incentive-based programs. The analysis and selection of new conservation measures is discussed in Chapter 5.0. Implementation of these new conservation measures will help the District meet the following water conservation goals:

1. By the year 2000, reduce overall per-capita water use by 8 percent through conservation relative to the District's base year of 1989 when the District began implementation of conservation programs. It is anticipated that the District will achieve a per-capita water consumption reduction in excess of the 8 percent goal in 1998.
2. Reduce single- and multi-family residential unit demand.
3. Reduce total peak day demand.
4. Explore markets and opportunities to conserve potable water supplies by using reclaimed water to meet non-potable water demand in the District.

An economic analysis was used to compare the unit cost of implementing a conservation measure with the expected unit cost of purchasing Second Supply Project (Pipeline 5) water from Tacoma. The expected water cost of the Second Supply Project is representative of the marginal cost of the District's water supply (e.g. the cost of the next increment of water supply). As such, it represents the economic cost of new water supplies (beyond current and pending supplies) that can be avoided through water conservation. This analysis is based on anticipated water savings, capital cost estimates, and annual operating cost estimates. Measures that had a unit cost of implementation cheaper than the unit cost of supply are recommended for District consideration.

Implementation schedules and costs for the selected measures are shown in Table 5-7. Measures not selected for implementation should be reevaluated in the District's next update of the comprehensive water system plan; the unit cost of supply may increase compared to the unit cost of conservation measure implementation.

Projected per-capita water savings are listed in Table 5-8. The District's reduction in per-capita water use relative to 1989 is expected exceed the goal of 8 percent for 2000.

Water reuse is an additional form of conservation that the District is exploring. Potential water reuse applications addressed in Chapter 6.0 are landscape irrigation, commercial indoor use for non-potable applications (e.g., toilet flushing), and aquifer recharge. Chapter 6.0 also presents the analysis results of developing a reclaimed water system to provide commercial landscape irrigation in several areas of Federal Way. The potential role of aquifer recharge with reclaimed water, either through surface spreading or direct injection, is also discussed in Chapter 7.0.

Water reuse for commercial indoor non-potable applications and commercial landscape irrigation does not appear to be economically competitive with purchasing Second Supply Project water from Tacoma. Accordingly, the reclaimed water system discussed in Chapter 6.0 is not recommended for implementation at this time.

Aquifer recharge with reclaimed water has not been fully explored by the District. Future feasibility studies will focus on various potential surface spreading and direct injection sites located throughout the District. The District plans to implement cost-effective and feasible aquifer recharge projects as warranted by future supply needs.

The District has developed a water supply plan to meet the District's potable water demands with a goal of bringing water supplies on-line just prior to their need. To meet this goal, the District evaluated the feasibility of using existing, interim, potential, and pending water supplies. Seasonal and long-term water management strategies were also considered to optimize the use of water resources.

The District's existing water sources are predominantly groundwater supplies. The District's groundwater supplies originate from four aquifer systems: the Redondo-Milton Channel (RMC) Aquifer, Mirror Lake Aquifer (MLA), Eastern Upland (EUP) Aquifer, and the Federal Way Deep (Deep) Aquifer. The combined production limit for these aquifers on an average-annual basis is 10.1 MGD during average precipitation and 9.0 MGD during a simulated 10-year drought. The current peak-day combined pumping capacity is 31.0 MGD. The District has secured water rights for all of its active wells except Well 25. See Section 7.2.4 for further discussion of water rights associated with the District's wells. The District is also completing a Wellhead Protection Program intended to identify the areas contributing water to the wells supplying the water system and to develop an appropriate management plan to protect water quality (see Section 7.2.3).

The District has secured interim water supplies by initiating water deliveries from Tacoma through two existing interties to accommodate ongoing growth. These water deliveries are primarily surface water diversions from the Green River. The agreement provides for delivery of up to 1.8 MGD during the period from May through October and up to 5.8 MGD during the period from November through April.

The District and Tacoma recently negotiated completed an agreement to construct the NE Tacoma/Federal Way Transmission Main and purchase wholesale water. This 5.8 mile long transmission main will be financed by the District and become the lower portion of Second Supply Pipeline when it is complete. The District would receive an appropriate credit for its remaining capital cost share of the Second Supply Pipeline Project. Prior to completion of the Second Supply Project, Tacoma will provide the District 2 MGD of firm water with a maximum delivery rate of 3 MGD. Up to 5 MGD of winter water may also be purchased on an as-available basis with a maximum delivery rate of 7 MGD. This wholesale water supply agreement remains in effect until the Second Supply Project is completed and the District able to take full delivery of its agreed upon water from the Second Supply Pipeline. The NE Tacoma/Federal Way Transmission Main is expected to be operational in April 2000.

Tacoma, the District, and other South King County purveyors have negotiated the Conceptual Agreement for the Second Supply Pipeline and Associated Components. Key provisions to the District include the right to use approximately 1/9th (7.2 MGD) of the Second Diversion Water Right, the right to at least 1/9th of the pipeline's capacity and the unused capacity of others at no cost, the right to participate in Howard hanson Storage - Phase II, and other provisions. Potential water supplies that are also discussed in Chapter 7.0 include: additional groundwater from the Eastern Upland Aquifer, winter water from Seattle Public Utilities, emergency intertie with the City of Auburn, water reclamation for aquifer recharge, Pierce County groundwater, seawater desalination, and barged water.

Since water supply availability does not often coincide with water demand patterns, optimal uses of available water supplies is difficult. The District is developing water management strategies that will minimize this difficulty, utilizing aquifer storage and surface reservoir storage schemes. The District has been exploring the feasibility of aquifer storage and recovery (ASR) in its MLA and RMC aquifers since 1993. The original concept for the MLA aquifer was named Optimization of Aquifer Storage for Increased Supply (OASIS). The District has completed feasibility studies and since January 1998 has conducted field studies using groundwater for ASR in the MLA. The District will use surface water for ASR field studies once the Northeast Tacoma/Federal Way Transmission Main is complete. The main will convey the required surface water supply to the central part of the water system for ASR testing. The District also plans to expand its ASR program to include recharge of the RMC aquifer, either with surface water or reclaimed water. Aside from ASR testing, the District is exploring water management strategies associated with the Howard Hanson Dam Additional Water Storage Project, discussed in section 7.6.2.

The recommended water management plan consists the following water supply, water management, and resource utilization recommendations.

• Complete and start-up the NE Tacoma/Federal Way Transmission Main by 2000.
• Continue participation in the Second Supply Project and develop a cost containment strategy and program management strategy to provide completion by 2004.
• Develop additional water supplies as required by water demand growth.
• Evaluate the need for additional water supplies on an ongoing basis.
• If more cost-effective supplies are developed, consider using the less cost-effective supplies to provide wholesale water to other utilities.
• Continue development of the ASR program so it is available in 2004 and solicit regional participation.
• Continue participation in the Howard Hanson Storage Project - Phase I, develop a cost containment strategy, and encourage increased Federal participation.
• Continue participation in Howard Hanson Storage Project - Phase II until sufficient information is developed to allow economic analyses.
• Until the Second Supply Project is complete, continue to balance the objectives of maintaining groundwater levels and providing a low-cost water supply by maximizing the use of wholesale Tacoma water, as practicable, and complementing this supply with groundwater up to its sustainable yield of 10.1 MGD.
• When the Second Supply Project is completed, utilize this water to the maximum extent possible including the use of unused winter water of other project participants.
• Fill the District's capacity in Howard Hanson Storage Project - Phase I as soon as possible to assure water supply availability during peak demand periods and allow Second Supply Project water to be used in May and June.
• Maximize the use of the District's capacity in Howard Hanson Storage Project - Phase I and utilize releases during the peak demand period.
• When the District or other Second Supply Project participants have unused stored water in Howard Hanson Storage Project - Phase I on 1 October, utilize this water for groundwater recharge or "in-lieu-of-direct-use" in the District's ASR program.
• Provide both seasonal and long-term ASR storage. In general, use the RMC Aquifer for seasonal storage and the MLA for long-term storage.
• Utilize Second Supply Project water not directly used by the District or other participants for ASR.
• Utilize groundwater during the Howard Hanson Storage Project - Phase I fill period to meet water demands during the summer and to meet peak daily demands.
• Continue to implement a water conservation program.
• Evaluate and explore wholesale water sales to other utilities as excess water supply becomes available.

Design and construction standards for supply, storage, transmission, and distribution facilities were updated as part of this planning effort. These criteria are summarized in Chapter 8.0. These criteria are also discussed in the Lakehaven Utility District Water System and Sewer System Standards that are incorporated into this WSP by reference.

Level of service criteria were developed for fire protection service and are discussed in Chapter 8.0. The District worked with local fire authorities and State DOH officials to develop the following level of service policy goals that were adopted by the Board of Commissioners on 16 April 1998:

• For single-family residential areas, the District goal is to provide 1,000 gpm. Duplexes are assumed to be included in single-family residential areas.
• For multi-family, commercial, industrial, and institutional areas, the District goal is to provide 2,500 gpm.
• Changes in the Uniform Fire Code that require higher fire flow requirements will not be applied retroactively to existing facilities.

The existing water system consists of two major pressure zones: Pressure Zone 538 and subpressure zones (538 Zone), and Pressure Zone 578 and subpressure zones (578 Zone). Chapter 9.0 includes a water system schematic that depicts how existing facilities are oriented within these two major pressure zones (see Figure 9-1).

The 538 Zone has five storage tanks with a total volume of 13.85 million gallons (MG) including inactive volume, production access to 19 of the 20 active wells, and the District's only two continuously operating interties, Tacoma Interties No. 2 and 3. With nearly all of the supply provided initially to the 538 Zone, an important feature of the overall water system is the supply transfer from the 538 Zone to the 578 Zone. This is accomplished using three booster pump stations and Well 25, which can produce water directly to both major systems.

The 578 system has five storage tanks with a total volume of 16.0 MG and production access to two of the 20 active wells (Wells 10C and 25). An additional 1.5 MG of storage volume is available in Pressure Zone 334, which is supplied by gravity from the 578 system. Further description of the existing system is provided in Chapters 1.0 and 9.0.

Modeling analyses were conducted to evaluate the hydraulic and storage performance of the existing facilities to meet demand conditions in 2003 and 2017. The modeling analyses were performed using the District's Water Hydraulic Model that was developed and calibrated in 1994. This model allows the District to analyze the system under various storage, pumping, and demand condition scenarios.

For hydraulic analyses, static modeling (i.e., steady-state modeling) was performed. Chapter 9.0 discusses the various types of hydraulic conditions that were analyzed, including normal peak-day and peak-hour demand (PHD) conditions, fire flow events, the loss of a major booster pump station or storage component, and the addition of Pipeline 5 water in the 538 and 578 systems. These analyses are discussed in greater detail in Appendix F.

The hydraulic analyses results indicate that the system is capable of meeting level of service goals through 2017 with minor main improvements. Improvements scheduled by the District include upsizing mains near critical fire flow event locations (Sacajawea Junior High School and in the Grand View residential neighborhood), improving supply redundancy to Pressure Zone 490 and its subpressure zones, other miscellaneous improvements that address transmission reliability and excessive velocities during fire flow. The District is also implementing assessment and replacement programs for aging mains and service lines.

The hydraulic analyses identified several areas in the system that experience low-pressure due to their high elevation relative to the system's hydraulic grade. These areas receive adequate service pressure during fire flow events [greater than 20 pounds per square inch (psi)], but during PHD the pressure is less than the 30 psi criteria DOH implemented in 1978. DOH has indicated that the 30 psi minimum pressure requirement for PHD does not retroactively apply to water systems constructed prior to 1978. The District plans to make information available to customers in these areas on the use of individual booster pumps to increase service pressure.

For storage analyses, extended-period simulation modeling was conducted to evaluate the storage drawdown during fire flow events and to evaluate storage equalization during multiple-day periods of maximum-day demand conditions. Before the storage analyses were modeled, three different supply approaches were considered for providing equalization, fire suppression, and standby supply. Two of the approaches relied only on gravity storage to provide fire suppression and standby supply: the Basic Storage Approach and the Consolidated Storage Approach. Preliminary analyses showed that these approaches would require approximately 4 to 5 MG of additional storage (active plus inactive) by 2003. The third approach relied less on gravity storage to provide standby supply. This approach was the Backup Power Approach and was ultimately selected for planning purposes.

The key feature of the Backup Power Approach is that standby supply is to be primarily provided by wells and booster pumps equipped with backup power generation facilities. Several criteria were used to select which pumps should receive backup power. One criterion was that the combined capacity of the sources would approximately equal average-day demand. Gravity storage facilities under the Backup Power Approach are relied upon to provide equalizing and fire suppression supply.

The storage analyses model was conducted using the Backup Power Approach. Results are shown in detail in Appendix F and summarized in Chapter 9.0. Improvement requirements based on these storage analyses include the following:

• Installation of backup power at Wells 10, 10A, 16, 17B, 25, and at the 320th St. and 337th St. Booster Pump Stations.
• Seismic upgrade of the 312th St. Tank to keep it in service.
• Installation of additional boosting capacity to the 578 system, presumably near the intersection of 23rd Avenue South and South 320th Street.

The Backup Power Approach required much less capital investment in new facilities than the Basic and Consolidated Storage Approaches. The Backup Power Approach also improved the District's level of standby supply service. Standby supply will be available indefinitely from the pumped sources with backup power, whereas the Basic and Consolidated Storage Approaches provide for only one day of standby supply using gravity storage.

Historically, the District has not had to treat its water supplies prior to distribution. Groundwater quality has generally been sufficient. Chlorination (for disinfection purposes) is the only treatment regularly provided by the District at Well sites 15, 15A, 19/19A, and 21. Chlorination is provided at these sites because water from these wells is blended with chlorinated water imported from Tacoma. The Surface Water Treatment Rule (SWTR) requires purveyors to maintain a chlorine residual within the portions of the distribution system receiving surface water. Disinfection facilities are also present at Well sites 10C, 20, 22/22A, and 23/23A to provide hydrogen sulfide control and/or disinfection during seasonal and emergency situations.

The District's status with respect to regulated drinking water contaminants covered by the WAC 246-290 and anticipated water quality regulations is summarized in Chapter 10.0. Regulations that are prompting future treatment of the District's groundwater supplies are the Lead and Copper Rule (LCR), the anticipated Ground Water Rule, and the SWTR due to the increased distribution of surface water throughout the District's distribution system.

The LCR was developed to reduce the corrosivity of the water which can result in increased lead and copper concentrations at customer's taps. The District monitored lead and copper concentrations at selected high-priority sites (single-family residences with copper plumbing and lead soldered joints constructed after 1982). Tap monitoring results indicated that copper concentrations exceeded the Action Level and lead concentrations were well below the Action Level. As a result, the District must implement corrosion control measures to reduce copper concentrations at the tap. To accomplish this, the District plans to initially add a phosphate compound. If further treatment is necessary to lower copper levels, the District plans to adjust the pH with caustic soda at all wells with pH < 7.5. The pH of the water that the District purchases from Tacoma has already been adjusted to approximately 7.5 or 7.6.

The Ground Water Rule is part of a multi-barrier approach expected to be implemented by the EPA to preserve groundwater quality and protect customers from groundwater supplies that could contain microbiological contaminants. The District is already planning to disinfect it groundwater supplies so the impact of this rule is minimal. If the District was planning to not implement groundwater disinfection, then the Ground Water Rule may have required the District to disinfect.

The District decided to implement groundwater disinfection to avoid water quality impacts associated with mixing unchlorinated District groundwater with imported or wheeled chlorinated supplies. The District also wanted to avoid impacts from exporting unchlorinated District groundwater to other chlorinated systems. All active wells are scheduled to receive disinfection facilities. For budgetary purposes, disinfection using onsite generation of 0.8 percent sodium hypochlorite was assumed. However, the District plans to further investigate the use of gaseous chlorine, 12 percent sodium hypochlorite, and UV disinfection before treatment facilities are constructed.

The third component to the District's groundwater treatment plan is the addition of a phosphate compound to sequester iron and manganese at all active wells. Historically, the District has relied upon its ongoing main cleaning and flushing program to manage iron and manganese precipitate levels in the distribution system. The addition of pH adjustment and disinfection at District wells is expected to make iron and manganese more difficult to manage in the distribution system. The District plans to implement the sequestering treatment program in conjunction with cleaning and flushing efforts.

The District considered the merits of iron and manganese removal versus sequestering. It is estimated that removal treatment at just one site (Well 19A) costs approximately two to three times as much as sequestering at all active wells. Based on the cost disparity of removal versus sequestering treatment, the District opted to defer treatment to remove iron and manganese in favor of first trying the iron and manganese control with sequestering and main cleaning.

A six-year capital improvement plan has been prepared to schedule the completion of improvement projects between 1998 and 2003 and is discussed in Chapter 11.0. The capital improvement plan includes scheduling of 26 projects already initiated that will be completed during the next 6 years, 8 new necessary improvement projects, and 3 new optional improvement projects. The capital improvement plan also includes cost estimates for 15 unscheduled improvement projects. Scheduled costs for additional non-capital revenue requirements (e.g., treatment operation and maintenance, tank removals, etc.) are also summarized in Chapter 11.0. Table ES-3 summarizes the cost requirements of the District's six-year capital improvement plan.

Notes:
(a) Based on projected water demand.
(b) Six-year totals are rounded to the nearest $100,000.

An assessment of revenue requirements associated with the implementation of the capital improvement program includes the following findings and recommendations:

• Total future capital expenditures (ENR = 6659) through 2003 excluding the NE Tacoma/Federal Way Transmission Main and Second Supply Pipeline Projects are $21.8 million, including $3.9 million in expansion-related projects ($27.1 million with the NE Tacoma/FederalWay Second Supply Pipeline projects) and approximately $3.8 million in non-capital O&M related expenditures.
• New project funding of up to $29 million is available under existing user charges, proposed capital facilities charge revenues, and unencumbered reserves.
• Unscheduled project costs total $9.7 million. This could be debt funded, if supported with additional revenues. Alternatively, a review of individual project scheduling is recommended to determine the appropriateness of each project under District funding criteria.