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any changes were warranted. The project involved updating costs and confirming the LTCP met the four-overflows-per-year level-of-service requirement. In addition, the city wanted to know if some combination of green infrastructure or low-impact development (LID) technolo- gies could supplement or replace proposed LTCP gray infrastructure improvements in order to reduce costs and improve performance. Table 2 compares the existing CSO LTCP solution (column 2) with an optimized gray-only solution (column 3), the overall optimized gray-green solution (column 4), and a modified optimized solution with the effective- ness of the green infrastructure reduced by 50 percent (column 5). This type of comparison is invaluable to utility decision makers and other stakeholders involved in deciding how the city should proceed. The poten- tial $112 million (27 percent) cost reduction certainly received favorable attention from the Board of Public Works and the mayor, who would be called on to defend the recommended LTCP plans. In addition to cost savings or cost avoidance, the optimized solu- tion also demonstrated improved hydraulic performance relative to the previous LTCP. The hydraulic performance improvements included 32 percent greater CSO volume eliminated, reduced frequency of CSOs at three locations, and reduced surcharge levels resulting in fewer base- ment backup issues. Table 2. Baseline CSO LTCP solution vs. optimized solution and two other scenarios Cost Item Baseline Solution ($M) Gray-Only Solution ($M) Optimized Solution ($M) 50% Effective Green Solution Conveyance 149.83 114.40 114.40 114.40 Pump Station 0.00 1.25 1.25 1.25 Storage Tank 99.80 116.82 63.28 95.81 Linear Storage 42.66 13.96 13.96 13.96 Relining & RTC 13.04 6.18 4.85 5.34 Green Technology -- -- 27.39 19.04 Total Construction 305.34 252.62 225.13 249.80 Eng/Leg/Adm. (20%) 61.07 50.52 45.03 49.96 Total Capital Cost 366.40 303.14 270.16 299.76 Present Worth O&M; 46.61 40.84 29.40 37.45 TOTAL COST 412.01 343.98 299.56 337.21 Cost Avoidance -- $68M / 17% $112M / 27% $75M / 18% A separate ODS analysis was also performed to optimize stag- ing of the 18 capital improvement projects in the plan. Figure 2 shows how the first five-year stage of the LTCP can achieve an overall reduction in uncontrolled overflows of 76 percent with the expenditure of just 21 percent of the total $270 million capital cost of the optimized LTCP. Los Angeles Bureau of Sanitation Optimization. LA BOS identified a small, but challenging problem facing their planning team. They desired to identify the best solution to augment reclaimed water supplies to one Figure 2. Optimized staging achieves maximum overflow reduction in near term. of their service areas during dry weather periods. A variety of options were identified, including construction of a dedicated pipeline between two existing plants and construction of new pipelines along allow- able routes to provide additional capacity within the service area. The options were formulated in the ODS software program with new pipe and pump station upgrade costs and service level criteria. The study demonstrated to LA BOS managers and engineers the ease of the opti- mization formulation and its ability to quickly develop and compare near-optimal solutions that may not have been identified using the nor- mal trial-and-error method. The estimated cost of the optimized alter- natives was just 50 percent of the original dedicated pipeline plan cost. Stormwater Optimization. The benefits of utilizing ODS for stormwa- ter optimization have been demonstrated through finding optimal solu- tions on combined sewer systems which are dominated by stormwater runoff. Recently, a more pointed approach to optimization was adopted on a stormwater collection system in Texas. ODS was used to select improvement options that would eliminate flooding under the 100-year- storm design, for a portion of its stormwater network. The city provided an EPA SWMM model for an area covering 29 subcatchments. The optimization was formulated to consider 87 new pipe and 6 storage options as well as green infrastructure options to reduce surface runoff in each of the subcatchments. The project demonstrated how ODS could be utilized for stormwater applications to mitigate flooding at least cost. ODS: A True Technological Innovation A powerful technological innovation is changing the way utility managers and engineers approach capital planning and operations of water systems. The ODS approach is founded upon advanced computationally intel- ligent software tools developed, tested, and proven over the past 19 years with leading utilities in the U.S., Canada, Australia, New Zealand, the U.K., and China. As ODS is utilized by more utility and consultant plan- ners and modelers, the ability to identify low-cost, near-optimal solutions will benefit stakeholders while providing a return on investment. wateronline.com ■ Water Innovations Jeffery Frey, PE, co-founded Optimatics in 1996, after 15 years at Harza Engineering Company. About The Author 32 WORKFORCEPLANNING