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Agenda 2016 03-21 Final Full PER 3-11-16PRELIMINARY ENGINEERING REPORT US HIGHWAY 421 CORRIDOR WATER & WASTEWATER UTILITIES Prepared for: D a � L � +Z elpeFear Public Utility Authority Stewardsfup. Sustainab!H4. Service, March 2016 4\\k IIt1I/ /// GARp f 029.776 , G i V� GAR0�' a s E All z .f ° t 3 -i -16 Prepared by: ,,*NFK1NI&CiEED Hazen Table of Contents Technical Memoranda - Table of Contents • Technical Memorandum 1.0 Executive Summary • Technical Memorandum 2.0 Demand Projections v MCKIM &CREED Hazen • Technical Memorandum 3.0 Wastewater Infrastructure Alternatives Analysis • Technical Memorandum 4.0 Water Infrastructure Alternatives Analysis Figures • TM 1.0 Figure 1.1 - US 421 Corridor Zone Designation • TM 1.0 Figure 1.2 - Recommended Wastewater System Alternative • TM 1.0 Figure 1.3 - Recommended Water System Alternative • TM 2.0 Figure 2.1 - US 421 Corridor Zone Designation • TM 3.0 Figure 3.1 - Existing Utilities • TM 3.0 Figure 3.2 - Phase I Alternative 1: Pump Station /Force Main System • TM 3.0 Figure 3.3 - Phase I Alternative 2: Pump Station /Force Main System • TM 3.0 Figure 3.3.A - Phase I Optional Design Consideration "A" • TM 3.0 Figure 3.3.13 - Phase I Optional Design Consideration 'B" • TM 3.0 Figure 3.4 - Phase II Alternative 1: Pump Station /Force Main System • TM 3.0 Figure 3.5 - Phase II Alternative 2: Pump Station /Force Main System • TM 3.0 Figure 3.6 - Phase I Alternative 1: Gravity Sewer Collection System • TM 3.0 Figure 3.7 - Phase I Alternative 2: Force Main Header System Appendices • A112endix A - Duke Energy Sutton Plant Coal Ash Landfill Leachate Conveyance System Evaluation Technical Memorandum, January 2016 • A112endix B - New Hanover County & CFPUA Board of Directors PowerPoint Presentation This document was prepared by: McKim & Creed, Inc. 243 N. Front Street Wilmington, NC NC License No. F1222 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - TECHNICAL MEMORANDUM 1.0 EXECUTIVE SUMMARY Technical Memorandum 1.0 Executive Summary EXECUTIVE SUMMARY v MCKW&CREED Hazen This Preliminary Engineering Report (PER) has been developed to evaluate the feasibility of constructing public water and wastewater infrastructure throughout the US Highway 421 corridor in New Hanover County. The County recently completed a comprehensive study of the corridor, including potential economic growth projections that would benefit from the availability of public water and wastewater utilities. Subsequently, this PER has been developed utilizing the County projections in concert with Cape Fear Public Utility Authority ( CFPUA), who would ultimately own and maintain such infrastructure. Figure 1.1 provides the location of the development zones identified along the US Highway 421 that are the basis of the evaluation. Recommended Alternatives The recommended wastewater system will consist of a series of pump stations and sewer force mains to convey wastewater to the CFPUA system for treatment. The recommended water system will consist of the extension of potable water mains in the corridor to provide domestic water demands and well as fire flow requirements. The estimated project cost is $20.2M and the anticipated timeline to design, permit and construct is 36 months from the date of design award. The recommended alternatives will provide public water and wastewater service along the US Highway 421 corridor from the Pender County line to the Isabelle Holmes Bridge. The recommended alternatives for wastewater and water are as shown in Figure 1.2 and Figure 1.3 respectively. The initial cost of the project could be reduced by eliminating two wastewater pump stations (designated as PS 1 and PS 2 on Figure 1.2) that would serve smaller sub basins. Advantages and disadvantages of these cost reductions are shown in Table 1 below: Table 1— Wastewater Cost Reduction Options — Advantages and Disadvantages Advantages Disadvantages Provides a reduction in overall project cost Reduces initial effective area to be provided public wastewater service Maintains service to approximately 85% of Growth in the areas not provided public identified growth areas wastewater may be limited Pump Stations can be added in future with no Timeline required to provide infrastructure impact to infrastructure in the PS 1 basin at a future date Does not impact potable water service which would be provided through the entire corridor Reduction of schedule from 36 to 34 months US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - Technical Memorandum 1.0 Executive Summary The potential cost savings of these options are summarized in Table 2. Table 2 - Summary of Potential Project Cost Reduction Options v MCIQM &CREED Hazen Preferred Eliminate 1 Eliminate 2 Alternative Total Pump Station Pump Stations Cost $20.2M $19M $16.7M This report does not recommend the cost reduction options as they do not fulfill the full scope of the project. As noted, implementation of either cost reduction option will not hinder expansion or additions to the system at a future date. Appendix A of this report includes the Technical Memorandum Duke Energy Sutton Plant Leachate Conveyance System prepared for Duke Energy in conjunction with this PER. This document provided infrastructure recommendations to convey leachate from the proposed Duke coal ash landfill to the CFPUA system. Recent regulatory requirements have accelerated the Duke Energy schedule and the benefits of this configuration for Duke Energy would be limited. Currently, CFPUA is in discussion with Duke Energy to accommodate an estimated 56,000 gallons per day of leachate in the southern portion of the US 421 corridor via CFPUA Pump Station 12. A summary of the primary sections of the report are briefly described as follows: Technical Memorandum 2.0 Demand Projections - TM 2.0 provides an evaluation of the identified growth areas in the US Highway 421 corridor. An analysis of developable acreage, illustrative industries, and job creation was conducted in order to project water demands and wastewater flows that could be generated throughout the corridor. • Technical Memorandum 3.0 Wastewater Infrastructure Alternatives Analysis - TM 3.0 includes a detailed evaluation of feasible options to provide public wastewater infrastructure in the corridor. Alternatives were evaluated for interim and long -term phasing, opinions of cost, permit requirements, and anticipated schedule of implementation. Technical Memorandum 4.0 Water Infrastructure Alternatives Analysis - Corollary to TM 3.0, TM 4.0 provides a detailed evaluation of feasible options to provide public water infrastructure in the corridor. Alternatives included interim and long -term phasing, opinions of cost, permit requirements, and anticipated schedule of implementation. Additionally, fire flow capacities and water quality concerns are addressed in this TM. END OF TECHNICAL MEMORANDUM US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - mwm&c= FIGURE 1.1 US 421 CORRIDOR WATER AND SEWER UTILITIES PRELIMINARY ENGINEERING REPORT US 421 CORRIDOR ZONE DESIGNATION / CITY OF WILMINGTON `�wM&CM= FIGURE 1.2 RECOMMENDED ALTERNATIVE US 421 CORRIDOR WATER AND SEWER UTILITIES WASTEWATER SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE `�wm&cy= FIGURE 1.3 RECOMMENDED ALTERNATIVE US 421 CORRIDOR WATER AND SEWER UTILITIES WATER SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE TECHNICAL MEMORANDUM 2.0 DEMAND PROJECTIONS Technical Memorandum 2.0 Demand Projections 2.1 INTRODUCTION MCIQM &CREED Hazen The purpose of Technical Memorandum (TM) 2.0 is to provide an evaluation of demand projections for water and wastewater needs along the US Highway 421 corridor in New Hanover County through the year 2040. Projections have been derived by utilizing data presented in the Pathways to Prosperity: New Hanover County's Plan for Jobs and Investment report, dated March 2014, prepared by Garner Economics, LLC as well as information provided by the Renaissance Planning Group and New Hanover County staff. The findings and data provided by Garner Economics, the Renaissance Planning Group, and subsequent information compiled by County staff provided an analysis of developable acreage and illustrative industries that would be expected to populate the corridor, designated via numbered zones. Table 1 summarizes data provided from these sources. Refer to Figure 1 for a geographical depiction of the zone designations: Table 1 - US 421 Developable Acreage and Illustrative Industries US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - Immediately Zone Developable Illustrative Industries Acres Food Processing; Precision Manufacturing.; Cold 1 384 Acres Storage Distribution; Heavy Equip.; Pet Food; Pharma; 2 420 Acres Chemical; Precision Manufacturing.; Injection Molding; Boat Building 3 67 Acres Tool & Die; Metal Fabrication; Cold Storage 4 98 Acres High Value Office Operations/Headquarters Service Companies; Small Warehouse facilities; 5 13 Acres Boat Building Total Developable 982 Acres Acres US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - Technical Memorandum 2.0 Demand Projections MCIQM &CREED Hazen Further, the information provided delineation by job type and corresponding "building' square footage that would likely occur within the corridor. Table 2 provides a summary and comparison of job types and corresponding building square footages for three primary "investment" scenarios that were identified: • Conservative • Most Likely • Optimistic Table 2 - Projected Development Through 2040 Demand projections presented herein for water and wastewater needs have been based on the data provided in Tables 1 and 2 of this TM. 2.2 WASTEWATER DEMAND PROJECTIONS A primary challenge in estimating long -term utility demands is the high degree of variability possible with industrial /commercial customers. As an example, a Pharmaceutical industry typically requires intensive water -use, whereas other industries such as office space or warehouse facilities require minimal water -use relative to employees only. Given that the data provided did US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - Do- Nothing Investment Scenarios Scenario Conservative Most Likely Optimistic Square Feet 478,750 957,505 1,816,263 2,675,022 "Building" Jobs By Type & Percentage Lower Skill 239 100% 110 10% 209 10% 308 10% Industrial Higher Skill 0 0% 771 70% 1,462 70% 2,153 70% Industrial Commercial 0 0% 220 20% 418 20% 615 20% Total Jobs 239 1,101 2,089 3,076 Demand projections presented herein for water and wastewater needs have been based on the data provided in Tables 1 and 2 of this TM. 2.2 WASTEWATER DEMAND PROJECTIONS A primary challenge in estimating long -term utility demands is the high degree of variability possible with industrial /commercial customers. As an example, a Pharmaceutical industry typically requires intensive water -use, whereas other industries such as office space or warehouse facilities require minimal water -use relative to employees only. Given that the data provided did US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - Technical Memorandum 2.0 Demand Projections MCIQM &CREED Hazer not provide specific estimates or percentages of the type of industries anticipated for the corridor (reference Table 1), a variety of sources were examined in order to develop recommended wastewater demand projections. A sampling of sources evaluated included: • North Carolina Department of Environment and Natural Resources • Metcalf & Eddy • 2007 Wastewater Master Plan Update • CFPUA Integrated Water Resources Master Plan For the purposes of this PER, wastewater demands were developed for both industrial /process demands as well as sanitary demand loads associated with employees. The evaluated sources for industrial and process demands were primarily centered on factors associated with gallons /day /acre, which was ultimately used as the basis for projections presented herein. A wastewater flow rate of 300, 600 and 1,000 gal /acre /day respectively was assigned for industrial waste in zones 1 and 2 for the conservative, most likely and optimistic scenarios. In zones 3 and 5, the wastewater flow rates were assigned as 0, 100 and 150 gal /acre /day for each scenario. Based on data provided, Zone 4 was assumed as a primarily "commercial office building" use and therefore assumed to have sanitary loading (employee based) only. Based on the three investment scenarios noted in Table 2, flow rates for each category were estimated as follows in Table 3: Table 3 - Projected Industrial Flow in 2040 (gpd) Zone Immediately Developable Acres Industrial Flow Rate (gal /acre /d) Industrial Flow (gpd) Conservative Most Likely Optimistic Conservative Most Likely Optimistic 1 384 300 600 1,000 115,200 230,400 384,000 2 420 300 600 1,000 126,000 252,000 420,000 3 67 0 100 150 0 6,700 10,050 4 98 0 0 0 0 0 0 5 13 0 100 150 0 1,300 1,950 Totals (gals /day) 241,200 490,400 816,000 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 3 - Technical Memorandum 2.0 Demand Projections MCIQM &CREED Hazer In addition to industrial /process wastewater demands, demands specific to employee sanitary loads were also evaluated. Sanitary loadings are typically more uniform than industrial waste and are commonly based on a gal /employee /shift /day factor. Based on the sources evaluated, Metcalf & Eddy was recommended for estimation of the sanitary waste load with a demand factor of 25 gal /employee /shift. For zones 1 through 3, three 8 -hour working shifts were assumed, as all industries in these zones are primarily process based. For zones 4 and 5, one 8 -hour working shift was assumed. Table 4 provides a summary of sanitary waste load per zone. Table 4 - Projected Sanitary Flow in 2040 (gpd) Zone Flow Factor (gal /emp) No. Shifts Projected No. Employees Projected Sanitary Flow (gpd) Conservative Most Likely Optimistic Conservative Most Likely Optimistic 1 25 3 368 698 1,028 27,600 52,350 77,100 2 25 3 403 764 1,125 30,225 57,300 84,375 3 25 3 92 175 258 6,900 13,125 19,350 4 25 1 220 418 615 5,500 10,450 15,375 5 25 1 18 34 50 450 850 1,250 Totals 1,101 2,089 3,078 70,675 134,075 197,450 Table 5 provides summation of the combined process /industrial and sanitary /employee wastewater demands for the corridor. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 4 - Technical Memorandum 2.0 Demand Projections Table 5 - Projected Total Wastewater Demand 2040 (gpd) 4:e4 MCMM &CREED Hazen Pursuant to the scope of work for this PER, projected demands and associated infrastructure upgrades will be focused on the Most Likely (ML) and Optimistic (OP) Scenarios. Table 6 provides a uniform projection of demands over the project planning period through 2040 for the ML and OP scenarios. Table 6 - Projected Incremental Total Flow Wastewater Demands (gpd) Zone Projected Total Flow (gpd) Zone Conservative Most Likely Optimistic 1 142,800 282,750 461,100 2 156,225 309,300 504,375 3 6,900 19,825 29,400 4 5,500 10,450 15,375 5 450 2,150 3,200 Total 311,875 624,475 1,013,450 Pursuant to the scope of work for this PER, projected demands and associated infrastructure upgrades will be focused on the Most Likely (ML) and Optimistic (OP) Scenarios. Table 6 provides a uniform projection of demands over the project planning period through 2040 for the ML and OP scenarios. Table 6 - Projected Incremental Total Flow Wastewater Demands (gpd) Zone 2020 2025 2030 2035 2040 ML OP ML OP ML OP ML OP ML OP 1 56,550 92,220 113,100 184,440 169,650 276,660 226,200 368,880 282,750 461,100 2 61,860 100,875 123,720 201,750 185,580 302,625 247,440 403,500 309,300 504,375 3 3,965 5,880 7,930 11,760 11,895 17,640 15,860 23,520 19,825 29,400 4 2,090 3,075 4,180 6,150 6,270 9,225 8,360 12,300 10,450 15,375 5 430 640 860 1,280 1,290 1,920 1,720 2,560 2,150 3,200 Totals 124,895 202,690 249,790 405,380 374,685 608,070 499,580 810,760 624,475 1,013,450 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 5 - Technical Memorandum 2.0 McKIM&CREED Demand Projections Hazen 2.3 DUKE-PROGRESS ENERGY SUTTON LANDFILL LEACHATE In addition to the projected commercial and industrial demands for the corridor, CFPUA and Duke-Progress Energy has entered into an agreement to investigate the impacts of accommodating landfill leachate from a proposed coal ash landfill near the Duke-Progress Energy Sutton Plant (anticipated leachate generation rates are provided in Table 7). Based on information provided by Duke-Progress Energy, leachate generation will range from approximately 50,000 GPD to a peak of 186,000 GPD over a 12 year period. Therefore, the impacts of leachate generation in the range of 50,000 GPD to 186,000 GPD will be evaluated as part of the alternatives analysis conducted in this document. For the purposes of this report, it is assumed that CFPUA will require Duke-Progress Energy to meet all applicable pre-treatment regulations. Table 7 - Duke-Progress Energy Leachate Generation Rates (Figure I below) 200,000 180,00D 16o'con 140,030 120,000 a, 100,00 60.000 40.000 20,000 0 Figure 1. Leachate Life Cycle and Received Waste Summary Based on Peak Monthly Leachate Generation 2 El.p,ed Ti— (Ye—) 10 12 10,000,000 9,000'aDo 91000.000 7,000,000 6,000,000 F I 5'()00'()00 - 4,000,000 3,0()0,000 2,000,000 1,000,00() US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 6 - CCA b.ic placed in preWatianfe f in.ld- .... ................ > ♦ rf rr rr 2 El.p,ed Ti— (Ye—) 10 12 10,000,000 9,000'aDo 91000.000 7,000,000 6,000,000 F I 5'()00'()00 - 4,000,000 3,0()0,000 2,000,000 1,000,00() US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 6 - Technical Memorandum 2.0 Demand Projections 2.4 WATER DEMAND PROJECTIONS MCK M &CREED Hazen Water demand forecasts for the US Highway 421 Corridor were prepared using information from the previously noted sources as well as the New Hanover County Planning Department. As previously noted in this TM, data provided on potential industry types and the number of employees for the three investment scenarios was used to develop water demand projections for the corridor. Industrial water use can vary widely depending upon the type of industry. Industrial water use can include process water use, cleaning and sanitizing, building cooling, and domestic use. Multiple sources were used to develop a projection of unit water use for each mix of commercial and industrial uses based on the projected number of employees. Unlike wastewater demands, where flow factors are primarily focused on gallons /day /acre, water demands are historically derived on a per employee basis. A variety of sources were examined in order to develop recommended unit water use factors, including: • Water Distribution System Handbook, American Water Works Association (2000) • Water use data for other North Carolina water systems • Waste Not, Want Not: The Potential for Urban Water Conservation in California, Pacific Institute (2003) • Water Use Planning Guide, Ohio State University Given that the information provided did not provide specific estimates or percentages of the type of industries anticipated for the corridor, an average of the unit water use for each planned industry was used to establish the unit water use for each zone. Recommended water demand factors for each zone are provided in Table 8 as follows: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 7 - Technical Memorandum 2.0 Demand Projections Table 8 — Unit Water Demands 4:e4 MCMM &CREED Hazen Zone Industry Types Unit Water Use Zone Conservative (gpd /employee) 1 Food Processing, Precision Manufacturing, Cold 440 Optimistic Stora e 368 2 Distribution, Heavy Equipment 410 307,120 Pet Food, Pharmaceuticals, Chemicals, Precision 2 403 Manufacturing, Injection Molding, Boat Building 1,125 3 Tool and Die, Metal Fabrication, Cold Storage 140 4 High Value Office Operations, Headquarters 30 5 Service Companies, Small Warehouse Facilities. Boat 115 36,120 Building 220 The number of employees within each zone and industry was selected from the initial wastewater demand projections prepared for conservative, most likely and optimistic economic growth in the US 421 Corridor. As such the final demand projections for total water flow in gallons per day are shown in Table 9. Table 9 — Projected Total Water Demand 2040 (gpd) In conjunction with projected wastewater demands, projected water demands and associated infrastructure upgrades will be focused on the Most Likely (ML) and Optimistic (OP) Scenarios. Table 10 provides a uniform projection of demands over the project planning period through 2040 for the ML and OP scenarios. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 8 - Projected Number of Employees Projected Total Water Demand Zone Conservative Likely Optimistic Conservative Likely Optimistic 1 368 698 1,028 161,920 307,120 452,320 2 403 764 1,125 165,230 313,240 461,250 3 92 175 258 12,880 24,500 36,120 4 220 418 615 6,600 12,540 18,450 5 18 34 50 2,064 3,899 5,733 Totals 1,101 2,089 3,076 348,694 661,299 973,873 In conjunction with projected wastewater demands, projected water demands and associated infrastructure upgrades will be focused on the Most Likely (ML) and Optimistic (OP) Scenarios. Table 10 provides a uniform projection of demands over the project planning period through 2040 for the ML and OP scenarios. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 8 - Technical Memorandum 2.0 Demand Projections Table 10 - Projected Incremental Total Flow Water Demands (gpd) MCIQM &CREED Hazen 2.5 SUMMARY AND CONCLUSIONS Based on the information presented in the TM, it is recommended that the CFPUA and New Hanover County plan infrastructure improvements for the US Highway 421 corridor based on the demands as summarized in Table 11 below: Table 11- Summary of Projected Wastewater and Water Demands 2040 (gpd) Wastewater Projected Total Flow (gpd) 2020 2025 2030 2035 2040 Zone 1,013,000 661,000 974,000 Recommended Demands for Planning & Modeling Purposes Most Likely Optimistic ML OP ML OP ML OP ML OP ML OP 1 61,424 90,464 122,848 180,928 184,272 271,392 245,696 361,856 307,120 452,320 2 62,648 92,250 125,296 184,500 187,944 276,750 250,592 369,000 313,240 461,250 3 4,900 7,224 9,800 14,448 14,700 21,672 19,600 28,896 24,500 36,120 4 2,508 3,690 5,016 7,380 7,524 11,070 10,032 14,760 12,540 18,450 5 780 1,147 1,560 2,293 2,339 3,440 3,119 4,586 3,899 5,733 Totals 132,260 194,775 264,520 389,549 396,779 584,324 529,039 779,098 661,299 973,873 2.5 SUMMARY AND CONCLUSIONS Based on the information presented in the TM, it is recommended that the CFPUA and New Hanover County plan infrastructure improvements for the US Highway 421 corridor based on the demands as summarized in Table 11 below: Table 11- Summary of Projected Wastewater and Water Demands 2040 (gpd) Wastewater Projected Total Flow (gpd) Water Projected Total Flow (gpd) Most Likely Optimistic Most Likely Optimistic 624,000 1,013,000 661,000 974,000 Recommended Demands for Planning & Modeling Purposes Most Likely Optimistic Most Likely Optimistic 660,000 GPD 1.0 MGD 660,000 GPD 1.0 MGD END OF TECHNICAL MEMORANDUM US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 9 - mwm&c= FIGURE 2.1 US 421 CORRIDOR WATER AND SEWER UTILITIES PRELIMINARY ENGINEERING REPORT US 421 CORRIDOR ZONE DESIGNATION TECHNICAL MEMORANDUM 3.0 WASTEWATER INFRASTRUCTURE ALTERNATIVES ANALYSIS Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis 3.1 INTRODUCTION & BACKGROUND Technical Memorandum 3.0 (TM 3.0) provides a detailed evaluation of collection and conveyance alternatives for wastewater needs projected along US Highway 421 corridor in New Hanover County, NC. As detailed in TM 2.0, the corridor was segmented into five development zones and wastewater generation was projected in each zone for two primary scenarios, Most Likely and Optimistic. A summary of the projected wastewater demand is provided in Table 1 below: Table 1— Projected Total Wastewater Demand by 2040 Zone ** Projected Total Flow (GPD) Most Likely Optimistic 1 282,750 461,100 2 309,300 504,375 3 19,825 29,400 4 10,450 15,375 5 2,150 3,200 Total 624,475 1,013,450 Total Recommended in TM 2.0 660,000 1,000,000 * *Note: Refer to Figure 2.1, Technical Memorandum 2.0 for the geographical location of each zone. For the purposes of this document, alternatives evaluated were based on the following general criteria: All wastewater collected in the project area would be conveyed to the CFPUA Northside WWTP for treatment. • Two (2) primary areas were identified as feasible connection points to the CFPUA System: ✓ Chair Road Pump Station ✓ Pump Station No. 12 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Utilize two (2) existing 8 -inch HDPE DR9 mains recently installed under the NE Cape Fear River near the Isabelle Holmes Bridge if feasible. It is noted that the mains are currently not in service and were specifically installed to be utilized as sewer force mains to provide future service to the US 421 corridor. The alternatives would be based on a phased approach, providing for a system designed to accommodate intermediate needs (Phase I) of the corridor and expandable to meet the long -term 2040 needs (Phase II) identified in Table 1 of this TM. Per consultation with New Hanover County and CFPUA, it was determined Phase I infrastructure would be based upon 50% of the projected wastewater generation for the corridor (refer to Table 1A below). Additionally, Phase I would be focused on the Most Likely scenario as this would provide the most cost effective approach for initial project costs and flexibility for expansion of the infrastructure to accommodate growth. Resultantly, the alternatives presented herein are summarized as follows: Table 1A — Phased Alternative Approach Therefore, infrastructure for Phase I would be evaluated for 330,000 GPD and Phase II would be evaluated for an additional 330,000 GPD (660,000 GPD Total) for the Most Likely scenario and an additional 670,000 (1 MGD Total) for the Optimistic scenario. 3.2 EXISTING FACILITIES Based on review of available information, the following public utility infrastructure exists within the US Highway 421 corridor (See Figure 3.1): • Lower Cape Fear Water & Sewer Authority 48 -inch raw water main on the east side of 421 • CFPUA 48 -inch raw water main on the east side of 421 • CFPUA Flemington water system improvements (currently under construction) US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - Projected Total Flow (GPD) Most Likely Optimistic Phase I (Intermediate) 330,000 N/A Phase II (2040 Total) 660,000 1,000,000 Therefore, infrastructure for Phase I would be evaluated for 330,000 GPD and Phase II would be evaluated for an additional 330,000 GPD (660,000 GPD Total) for the Most Likely scenario and an additional 670,000 (1 MGD Total) for the Optimistic scenario. 3.2 EXISTING FACILITIES Based on review of available information, the following public utility infrastructure exists within the US Highway 421 corridor (See Figure 3.1): • Lower Cape Fear Water & Sewer Authority 48 -inch raw water main on the east side of 421 • CFPUA 48 -inch raw water main on the east side of 421 • CFPUA Flemington water system improvements (currently under construction) US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - v MCMM&CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • CFPUA parallel 8 -inch HDPE DR9 force mains installed under the NE Cape Fear River • NC natural gas 12 -inch gas main on west side of US Highway 421 • Underground cables, varying in type, number, and location. • Duke- Progress Energy Overhead transmission and distribution lines • CSX Railroad right -of -way & private service /spur tracks Based on the information available there are no public wastewater facilities located on the US Highway 421 corridor in New Hanover County, exclusive of the parallel 8 -inch force mains recently installed under the NE Cape Fear River. Preliminary routing of the proposed infrastructure has been included as part of this evaluation, however, a more detailed analysis would be required as part of detailed design to ascertain a more definitive location of utilities and incorporate into design of infrastructure construction in the corridor. 3.3 CORRIDOR PLANNING APPROACH The general approach to provide wastewater infrastructure in the corridor was based upon a pump station and force main configuration, whereby wastewater flow would be collected in wastewater pump stations and conveyed to the CFPUA system via corresponding sewer force mains. Localized collection of wastewater would be accomplished either by conventional gravity sewer or by a force main collection header that would discharge to the primary pump station system. The primary pump stations were evaluated for strategic locations to utilize the area topography, accommodate local collection infrastructure, and ultimately optimize the service area for each station. For conveyance to the existing CFPUA wastewater system, two primary connection points were identified as feasible to accommodate the proposed wastewater infrastructure on US Highway 421 (See Figure 3.1): Connection Point 1 Chair Road PS (CRPS) - The CRPS is located in the Wrightsboro area of northwest New Hanover County. Initial investigation of this connection point yielded the following: CRPS is centrally located to Zones 1 and 2 of the corridor, where the vast majority of wastewater needs are projected. It would require the least amount of total force main infrastructure when compared to Connection Point 2. • CRPS has sufficient capacity to accommodate the Phase I demands, but would likely require upgrades to meet the total projected Phase II demands. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 3 - v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • CRPS would require the acquisition of significant easements parallel to an existing Duke- Progress Energy easement A crossing of the NE Cape Fear River would be required via horizontal directional drill and is estimated at approximately 4,000 feet in length. This would be a significant cost and permitting factor for connection to the CRPS. Connection Point 2 CFPUA PS 12 (PS 12) - PS 12 is located at the end of Cowan Street in the City of Wilmington and is immediately adjacent to the east bank of the NE Cape Fear River. Initial investigation of this connection point yielded the following: • PS 12 is located in the southernmost reaches of the corridor in New Hanover County. • Two 8 -inch HDPE DR9 force mains were recently installed by CFPUA under the NE Cape Fear River for the purposes of future sewer service to the corridor and would ultimately discharge directly to PS 12 with minimal piping required. The two 8 -inch force mains were constructed utilizing DR9 HPDE and have an effective inside diameter of 6.92- inches each. • Utilization of the two HDPE DR9 force mains provides a readily available connection to the CFPUA system and provides duality with respect to the infrastructure under the river. It would also eliminate the need for crossing the NE Cape Fear River via horizontal directional drill. • This connection point requires an additional 6,000 linear feet of total sewer force main when compared to Connection Point 1. Collection System Approach As noted, two primary systems have been evaluated for localized collection within the corridor. Collection Approach 1 Collection Approach 1 involves a conventional gravity sewer system utilizing sewer mains constructed at slope with corresponding manholes. Specifics of Collection Approach 1 are: • Gravity sewer collection systems are generally the most expensive type of collection system constructed when compared to low- pressure systems, headers, vacuum systems, etc. This is primarily due to depth of excavation, shoring, dewatering, equipment, and manpower. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 4 - v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • Gravity systems historically provide the most flexible point of connection for customers as service laterals can be installed from the customer and individual pumping systems are normally not required. • In the 421 corridor, the seasonal water table is very shallow and significant dewatering is anticipated, which will add significant cost to construction of such a system. • In areas of large, undeveloped tracts, construction of gravity sewer ahead of development does not always coincide with the pattern(s) of development that actually occurs and additional gravity sewer is often required. • Pump stations that collect wastewater from gravity sewer systems must be designed and constructed at corresponding depths to accommodate the gravity inflow, which can increase overall project costs. Collection Approach 2 Collection Approach 2 involves a force main collection header system utilizing small diameter force mains strategically located to provide wastewater service to individual properties. Specifics of Collection Approach 2 are: • A force main header system will be less expensive than a conventional gravity sewer system, as the pipelines can be constructed at a minimal depth (3 feet below grade). • The force main header will require customers to construct an individual pump station that would connect to the header. • Given the small diameter and relative ease of construction, a small diameter force main header can be constructed to accommodate short -term, Phase I capacities and paralleled at a future date to coincide with growth. • Routing for a force main header has more flexibility as it does not require straight pipe installation and manholes necessary with conventional gravity sewer systems. • Force main headers could potentially provide for shallower pump station construction resulting in reduced project costs. The following sections provide a detailed description of the alternatives evaluated for the Pump Station & Force Main System approach as well as the Collection System approach. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 5 - v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis 3.4 PHASE I - ALTERNATIVES ANALYSIS FOR PUMP STATION & FORCE MAIN SYSTEM As previously addressed, projected wastewater flow ( >90 %) in the corridor will predominantly occur in Zones 1 and 2. While Zones 3, 4 and 5 have potential for growth, demands are projected to be minimal and the tracts identified are relatively sparse and non - contiguous in most areas. Figure 2.1 (Technical Memorandum 2.0) provides a graphical depiction of the development zones identified for this document. Therefore, the primary focus of the Alternatives Analysis for infrastructure improvements will be centered on Zones 1 and 2. It is anticipated that development in Zones 3, 4, and 5 will be served by smaller individual, manifold connections to the recommended force main system. Upon review of the area topography and the properties identified in Zones 1 and 2, a number of options were examined for the location of pump station and force main infrastructure along the corridor. These included multiple pump station locations and force main routes to best serve the corridor properties and convey wastewater collected to the CFPUA system. Ultimately, the topography and properties to be served yielded a three -pump station configuration with corresponding force mains that provided the most cost effective and feasible approach to conveyance of wastewater on the corridor. The following discussion of Alternatives 1 and 2 are based upon the identified three -pump station configuration. Phase I Alternative 1- Discharge to CFPUA Chair Road Pump Station (Connection Point 1) Alternative 1 involves construction of (3) three pump stations and corresponding force mains as follows (See Figure 3.2). Pump Station 1 (PS 1) will be located west of US Highway 421, approximately 1,500 feet south of the Pender County /New Hanover County line. This station will be located north of a low area under US Highway 421 and will provide for wastewater service for the properties between the low area and the county line. PS 1 will discharge via force main to Pump Station 2, where the wastewater flow will be collected and re- pumped. • Pump Station 2 (PS 2) will be located on the west side of US Highway 421 and opposite the Invista industrial site. The proposed PS 2 force main will follow US Highway 421 south and then parallel a Duke Energy -owned transmission easement northeasterly, where it will then be installed under the NE Cape Fear River via directional drill. It is anticipated that easements will be required parallel to the Duke Energy easement as current Duke policies would likely not allow the force main to be constructed within the easement. At this point, the force main would be routed to CFPUA's CRPS, where it would ultimately be conveyed to the Northside WWTP for treatment. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 6 - Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Pump Station 3 (PS 3) will be located directly on the east side of US Highway 421 generally in the vicinity of Sutton Steam Plant Rd. The corresponding force main would follow US Highway 421 north and manifold with the PS 2 force main near the Duke -owned transmission easement, where it will also convey wastewater flow to the CRPS. As part of the analysis, pump station and force main sizing were evaluated based on the average daily flow (ADF) identified in Table 1 and Table 1A. For compliance with North Carolina Department of Environmental Quality ( NCDEQ) Minimum Design Criteria, a minimum peak hourly factor of 2.5 was applied to the ADF to determine minimum pump rates and force main velocities. Summarily, Table 2 provides the pumping capacity based on the NCDEQ Minimum Design Criteria established for the alternatives analysis: Table 2 — Phase I - Pumping Capacity Minimum Design Criteria *PS 2 ADF includes the ADF from PS 1. Utilizing the proposed Phase I, Alternative 1 configuration, hydraulic modeling was conducted to determine viable pipe diameters required to meet the minimum pumping rates for each pump station. Table 3 provides hydraulic modeling results for potential pipe sizes for the proposed force main configurations and recommended pipe diameters for each force main segment. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 7 - Minimum Recommended Pump ADF Peak Hourly Required Pump Pump Rate Station (GPD) Factor (PHF) Rate (GPM) (GPM) PS 1 33,000 2.5 57 80 PS 2 307,500 2.5 534 535 PS 3 22,500 2.5 40 80 *PS 2 ADF includes the ADF from PS 1. Utilizing the proposed Phase I, Alternative 1 configuration, hydraulic modeling was conducted to determine viable pipe diameters required to meet the minimum pumping rates for each pump station. Table 3 provides hydraulic modeling results for potential pipe sizes for the proposed force main configurations and recommended pipe diameters for each force main segment. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 7 - Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 3 — Hydraulic Results Phase I Alternative 1 The pipe diameters recommended in Table 3 meet the criteria for minimum velocity of 2 feet per second and are within the pressure rating of the CFPUA standard C900 DR 18 (235 psi). Based on the recommended pipe diameters, each pump station was evaluated for motor horsepower and wetwell sizing, which is summarized in Table 4. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 8 - Recommended Force Main Pipe Segment Pipe Diameter Evaluated Design Peak Pump Rate or Total Force Main Velocity at Design Peak Pump Rate Maximum Force Main Pressure Recommended Pipe Diameter Flow 4" 80 GPM 2.1 FPS 18 psi PS 1 to PS 2 4" 6" 80 GPM 0.9 FPS 5 psi PS 2 to Duke 6" 535 GPM 6.1 FPS 139 psi Transmission 8" 8" 535 GPM 3.4 FPS 70 psi Easement PS 3 to Duke 4" 80 GPM 2.1 FPS 50 psi Transmission 4" 6" 80 GPM 0.9 FPS 40 psi Easement Duke Transmission Easement to CRPS 6" 615 GPM 7.0 FPS 170 psi 8„ 8" 615 GPM 3.9 FPS 46 psi The pipe diameters recommended in Table 3 meet the criteria for minimum velocity of 2 feet per second and are within the pressure rating of the CFPUA standard C900 DR 18 (235 psi). Based on the recommended pipe diameters, each pump station was evaluated for motor horsepower and wetwell sizing, which is summarized in Table 4. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 8 - Technical Memorandum 3.0 v MCMM&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 4 — Pump Station Design Recommendations * *Refer to Technical Memorandum Duke Energy Sutton Plant Leachate Conveyance System, which is provided as an Appendix to this document. The proposed system has been modeled to accommodate the hydraulic impacts associated with leachate flow that would be generated from Duke's proposed the coal ash landfill at the Sutton Power Plant. Should Duke Energy choose not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. Each pump station noted in Table 4 is based on a duplex operation with one pump as standby and one pump as the firm capacity, duty pump. As shown in Table 4, the wetwell diameter for PS 2 is recommended as 12 foot diameter to accommodate future capacity needs. This wetwell diameter will allow for a triplex configuration, improving flexibility and reducing individual pump motor sizes. Preliminary Route Considerations - Phase I, Alternative 1 A preliminary review of the specifics associated with the Phase I, Alternative 1 route are provided as follows (See to Figure 3.2): Phase I, Alternative 1 requires a total of 22,000 total linear feet of 8" force main and 8,000 LF of 4" Force Main. A 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 9 - Recommended Pumping Total Dynamic Wet Well Size Design Peak Pump Pump Motor Size Station Head (diameter) Rate PS 1 80 GPM 43 feet 15 HP 6 feet PS 2 535 GPM 167 feet 100 HP 12 feet PS 3 80 GPM 122 feet 25 HP 6 feet Duke Leachate 325 GPM 81 feet 20 HP 6 feet PS ** * *Refer to Technical Memorandum Duke Energy Sutton Plant Leachate Conveyance System, which is provided as an Appendix to this document. The proposed system has been modeled to accommodate the hydraulic impacts associated with leachate flow that would be generated from Duke's proposed the coal ash landfill at the Sutton Power Plant. Should Duke Energy choose not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. Each pump station noted in Table 4 is based on a duplex operation with one pump as standby and one pump as the firm capacity, duty pump. As shown in Table 4, the wetwell diameter for PS 2 is recommended as 12 foot diameter to accommodate future capacity needs. This wetwell diameter will allow for a triplex configuration, improving flexibility and reducing individual pump motor sizes. Preliminary Route Considerations - Phase I, Alternative 1 A preliminary review of the specifics associated with the Phase I, Alternative 1 route are provided as follows (See to Figure 3.2): Phase I, Alternative 1 requires a total of 22,000 total linear feet of 8" force main and 8,000 LF of 4" Force Main. A 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 9 - v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • A 150 LF railroad crossing under is required within the right -of -way of US Highway 421. Tax records indicate that the railway in this area is privately owned, however, it is anticipated that NCDOT will govern the permitting of the crossing as it is a public right -of- way. • 4,000 LF of horizontal directional drill under the NE Cape Fear River. Significant environmental permitting is anticipated for this activity and would impact the overall project schedule • 300 LF of horizontal directional drill under the low area in the northern 421 corridor for conveyance from PS 1 to PS 2 will be required. • Utility pipeline easements are anticipated for areas along the force main routes due to conflicts that prevent the main from being constructed in the NCDOT right of way. • An easement, or fee simple acquisition, for each pump station site will also be required. Typical, municipal pump station sites range from 50 ft x 50 ft to 100 ft x 100 ft in size. inion of Probable Proiect Cost — Phase I, Alternative 1 The opinion of probable project cost for Phase I, Alternative 1 is presented in Table 5: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -10- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 5 - Opinion of Probable Project Cost - Phase I, Alternative 1 Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $150,000.00 LS $150,000 2 8" Force Main C900 PVC 14,000 LF $65.00 LF $910,000 3 8" Force Main DIP 2,000 LF $85.00 LF $170,000 4 4" Force Main C900 PVC 7,000 LF $50.00 LF $350,000 5 4" Force Main DIP 1,000 LF $70.00 LF $70,000 6 Bore and Jack 16" Diameter Steel Encasement 500 LF $250.00 LF $125,000 7 8" DI Carrier Pipe 500 LF $95.00 LF $47,500 8 Directional Drill HDPE Class 200 SDR9 5,500 LF $300.00 LF $1,650,000 9 Air Release Valve in Manhole 5 EA $5,000.00 EA $25,000 10 8" Gate Valves 6 EA $1,000.00 EA $6,000 11 DI Restrained Fittings 11,000 LBS $7.00 LBS $77,000 12 PS 1 Wastewater Pump Station 1 LS $800,000.00 LS $800,000 13 PS 2 Wastewater Pump Station 1 LS $1,500,000.00 LS $1,500,000 14 PS 3 Wastewater Pump Station 1 LS $900,000.00 LS $900,000 15 Remove and Replace Curb and Gutter 200 LF $30.00 LF $6,000 16 Remove and Replace Gravel Drives 500 SY $10.00 SY $5,000 17 Remove and Replace Asphalt Drives 500 SY $40.00 SY $20,000 18 Remove and Replace Concrete Drive 500 LF $80.00 LF $40,000 19 Silt Fence 7,000 LF $3.00 LF $21,000 20 Check Dam 50 EA $350.00 EA $17,500 21 Straw with Net Liner (Min. 8' wide roll) 5,000 LF $2.00 LF $10,000 22 Undercut Excavation w /Select Material 4,500 CY $15.00 CY $67,500 23 Stabilization Stone (6" Depth) 5,000 LF $3.00 LF $15,000 Subtotal $6,982,500 Contingency $2,094,750 Technical Fees $1,047,375 Land /Easement Acquisition $250,000 Total Opinion of Probable Project Cost $10,374,625 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -11- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Phase I Alternative 2 - Discharge to CFPUA Pump Station 12 (Connection Point 2) Alternative 2 is similar in configuration to Alternative 1 in that it includes three pump stations to collect and convey wastewater in the corridor and the location of the pump stations are identical to Phase I, Alternative 1. The primary difference is that Alternative 2 would convey wastewater flow to Connection Point 2 at CFPUA PS 12. Specifics of Alternative 2 are as follows (See to Figure 3.3): • The location of Pump Station 1 (PS 1) will be identical to Phase I, Alternative 1. PS 1 will discharge via force main to Pump Station 2, where the wastewater flow will be collected and re- pumped. The location of Pump Station 2 (PS 2) will be identical to Phase I, Alternative 1. The proposed PS 2 force main will follow US Highway 421 south and connect to the two (2) existing 8 -inch HDPE DR9 force mains installed under the NE Cape Fear River. The 8 -inch force mains would also require connection to PS 12 as well as a valved bypass around PS 12. PS 12 will convey the wastewater to the Northside WWTP for treatment. The location of Pump Station 3 (PS 3) will be identical to Phase I, Alternative 1. However, the force main for PS 3 would be of minimal length and would manifold with the force main from PS 2 that would discharge to PS 12. Similar to Phase I, Alternative 1, pump station and force main sizing were evaluated based on the average daily flow (ADF) identified in Table 1 and Table 1A. Table 2 provides the pumping capacity based on the NCDEQ Minimum Design Criteria established for the alternatives analysis: Table 6 - Phase II - Pumping Capacity Minimum Design Criteria *PS 2 ADF includes the ADF from PS 1. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -12- Minimum Recommended Pump ADF Peak Hourly Required Pump Pump Rate Station (GPD) Factor (PHF) Rate (GPM) (GPM) PS 1 33,000 2.5 57 80 PS 2 307,500 2.5 534 535 PS 3 22,500 2.5 40 80 *PS 2 ADF includes the ADF from PS 1. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -12- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Utilizing the proposed Phase I, Alternative 2 configuration, hydraulic modeling was conducted to determine viable pipe diameters required to meet the minimum pumping rates for each pump station. Table 7 provides hydraulic modeling results for potential pipe sizes for the proposed force main configurations and recommended pipe diameters for each segment. Table 7 —Hydraulic Results Phase I Alternative 2 The pipe diameters recommended in Table 7 meet the criteria for minimum velocity of 2 feet per second and are within the pressure rating of the CFPUA standard C900 DR 18 (235 psi). Based on the recommended pipe diameters, each pump station was evaluated for motor horsepower and wetwell sizing, which is summarized in Table 8. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -13- Recommended Force Main Pipe Segment Pipe Diameter Evaluated Design Peak Pump Rate or Total Force Main Velocity at Design Peak Pump Rate Maximum Force Main Pressure Recommended Pipe Diameter Flow PS 1 to PS 2 4" 80 GPM 2.1 FPS 18 psi 4„ 6" 80 GPM 0.9 FPS 5 psi PS 2 to PS 3 6" 535 GPM 6.1 FPS 139 psi 8„ 8" 535 GPM 3.4 FPS 70 psi PS 3 to PS 12 4" 615 GPM 7.0 FPS 165 psi 8„ 8" 615 GPM 3.9 FPS 35 psi Existing 8 -Inch 8" Single 615 GPM 5.3 FPS N/A HDPE under NE Cape Fear River N/A 8" Parallel 308 GPM Each 2.6 FPS N/A The pipe diameters recommended in Table 7 meet the criteria for minimum velocity of 2 feet per second and are within the pressure rating of the CFPUA standard C900 DR 18 (235 psi). Based on the recommended pipe diameters, each pump station was evaluated for motor horsepower and wetwell sizing, which is summarized in Table 8. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -13- Technical Memorandum 3.0 v MCMM&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 8 — Pump Station Design Recommendations * *Refer to Technical Memorandum Duke Energy Sutton Plant Leachate Conveyance System, which is provided as an Appendix to this document. The proposed system has been modeled to accommodate the hydraulic impacts associated with leachate flow that would be generated from Duke's proposed the coal ash landfill at the Sutton Power Plant. Should Duke Energy choose not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. Each pump station noted in Table 8 is based on a duplex operation with one pump as standby and one pump as the firm capacity, duty pump. As previously noted, the wetwell diameter for PS 2 is recommended as 12 foot diameter, which will allow for a triplex configuration for future conditions, improving flexibility and reducing individual pump motor sizes. Preliminary Route Considerations — Phase I, Alternative 2 A preliminary review of the specifics associated with the Phase I, Alternative 2 route are provided as follows: Phase I, Alternative 2 requires a total of 31,000 total linear feet of 8" force main and 8,000 LF of 4" Force Main. • A 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -14- Recommended Pumping Wet Well Size Design Peak Pump Head Pump Motor Size Station (diameter) Rate PS 1 80 GPM 43 feet 15 HP 6 feet PS 2 535 GPM 193 feet 100 HP 12 feet PS 3 80 GPM 88 feet 15 HP 6 feet Duke Leachate 325 GPM 78 feet 20 HP 6 feet PS ** * *Refer to Technical Memorandum Duke Energy Sutton Plant Leachate Conveyance System, which is provided as an Appendix to this document. The proposed system has been modeled to accommodate the hydraulic impacts associated with leachate flow that would be generated from Duke's proposed the coal ash landfill at the Sutton Power Plant. Should Duke Energy choose not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. Each pump station noted in Table 8 is based on a duplex operation with one pump as standby and one pump as the firm capacity, duty pump. As previously noted, the wetwell diameter for PS 2 is recommended as 12 foot diameter, which will allow for a triplex configuration for future conditions, improving flexibility and reducing individual pump motor sizes. Preliminary Route Considerations — Phase I, Alternative 2 A preliminary review of the specifics associated with the Phase I, Alternative 2 route are provided as follows: Phase I, Alternative 2 requires a total of 31,000 total linear feet of 8" force main and 8,000 LF of 4" Force Main. • A 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -14- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • A 150 LF railroad crossing under is required within the right -of -way of US Highway 421. Tax records indicate that the railway in this area is privately owned, however, it is anticipated that NCDOT will govern the permitting of the crossing as it is a public right -of- way. • 300 LF of horizontal directional drill is required under the low area in the northern 421 corridor for conveyance from PS 1 to PS 2. • Utility pipeline easements are anticipated for areas along the force main routes due to conflicts that prevent the main from being constructed in the NCDOT right of way. • An easement, or fee simple acquisition, for each pump station site will also be required. Typical, municipal pump station sites range from 50 ft x 50 ft to 100 ft x 100 ft in size Opinion of Probable Project Cost — Phase I, Alternative 2 The opinion of probable project cost for Phase I, Alternative 2 is presented in Table 10: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -15- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 10 - Opinion of Probable Project Cost - Phase I, Alternative 2 Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $135,000.00 LS $135,000 2 8" Force Main C900 PVC 25,000 LF $65.00 LF $1,625,000 3 8" Force Main DIP 2,000 LF $85.00 LF $170,000 4 4" Force Main C900 PVC 7,000 LF $50.00 LF $350,000 5 4" Force Main DIP 1,000 LF $70.00 LF $70,000 6 Bore and Jack 16" Diameter Steel Encasement 500 LF $250.00 LF $125,000 7 8" DI Carrier Pipe 500 LF $95.00 LF $47,500 8 12" Directional Drill HDPE Class 200 SDR9 1,500 LF $300.00 LF $450,000 9 8" Directional Drill HDPE Class 200 SDR9 500 LF $275.00 LF $137,500 10 Air Release Valve in Manhole 6 EA $5,000.00 EA $30,000 11 8" Gate Valves 8 EA $1,000.00 EA $8,000 12 DI Restrained Fittings 12,000 LBS $7.00 LBS $84,000 13 PS 1 Wastewater Pump Station 1 LS $800,000.00 LS $800,000 14 PS 2 Wastewater Pump Station 1 LS $1,500,000.00 LS $1,500,000 15 PS 3 Wastewater Pump Station 1 LS $900,000.00 LS $900,000 16 Remove and Replace Curb and Gutter 200 LF $30.00 LF $6,000 17 Remove and Replace Gravel Drives 500 SY $10.00 SY $5,000 18 Remove and Replace Asphalt Drives 800 SY $40.00 SY $32,000 19 Remove and Replace Concrete Drive 500 LF $80.00 LF $40,000 20 Silt Fence 8,000 LF $3.00 LF $24,000 21 Check Dam 60 EA $350.00 EA $21,000 22 Straw with Net Liner (Min. 8' wide roll) 5,500 LF $2.00 LF $11,000 23 Undercut Excavation w /Select Material In -place 1,500 CY $15.00 CY $22,500 24 Stabilization Stone (6" Depth) 6,000 LF $3.00 LF $18,000 Subtotal $6,611,500 Contingency $1,983,450 Technical Fees $991,725 Land /Easement Acquisition $200,000 Total Opinion of Probable Project Cost $9,786,675 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -16- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis PHASE I RECOMMENDATIONS Comparison of the Alternative 1 and Alternative 2 is provided in Table 11 as follows: Table 11- Phase I Alternatives Matrix Item Alternative 1 Alternative 2 Best Alternative Opinion of Probable Project Cost $10AM $9.7M 2 Total Length of Force Main 30,000 37,000 1 Diameter of Force Mains 4" & 8" 4" & 8" N/A Pump Station HP (PS 1, PS 2, PS 3) 15, 100, 25 15, 100, 15 N/A Directional Drill under NE Cape Fear River Yes No 2 Utilizes Existing CFPUA 8 -inch Directional Drills No Yes 2 Pump Stations Required 3 3 N/A Ease of Permitting No Yes 2 Overall Schedule No Yes 2 Based on the results presented in this report, Alternative 2 is the most cost effective alternative to provide wastewater infrastructure on the US 421 corridor to meet the Phase I criteria.. Summarily, Alternative 2 is comprised of the following: • 31,000 LF of 8 -inch force main and 8,000 LF of 4 -inch force main • Three (3) submersible wastewater pump stations to collect and convey wastewater to the CFFPUA system • Utilizes the existing CFPUA dual 8 -inch force mains under the NE Cape Fear River • Conveyance via CFPUA PS 12 to the Northside WWTP US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -17- v MCMM&CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis • Total Opinion of Probable Project Cost $9.7M Therefore, Alternative 2 is the recommended alternative for Phase I Pump Station and Force Main System. 3.5 PHASE I ALTERNATIVE 2 - OPTIONAL DESIGN CONSIDERATIONS Per the Scope of Work identified for this study, the Phase I alternatives presented in this TM were focused on providing wastewater service to all parcels identified in Zones 1 through 5 (See Figure 2.1, Technical Memorandum 2.0). During the course of preparing this study, consultations with CFPUA and New Hanover County indicated a desire to evaluate the recommended Phase I, Alternative 2 based on a reduced scope and maximize the potential cost benefit to provide initial wastewater service in the US 421 corridor. Recognizing that the majority of estimated wastewater flows will be generated in development Zones 1 and 2, the following optional design considerations for Phase I, Alternative 2 have been evaluated: Optional Design Consideration "A" - under this scenario Pump Station No. 3 (PS 3) will be eliminated from the initial Phase I, Alternative 2 project. The service area of PS 3 is projected to generate approximately 29,735 GPD of wastewater flow of the total estimated 660,000 GPD for the corridor, which equates to 4.5% of the total projected flow. Therefore, compared to the wastewater capacity it will serve, the cost benefit of constructing PS 3 as part of the Phase I project is minimal. Subsequently, this scenario provides wastewater service to all areas of Zones 1 and 2, with the flexibility that PS 3 can be constructed at a future date without detrimental impact to the recommended Phase I, Alternative 2 system. Figure 3.3A provides a schematic of Optional Design Consideration "A ". As shown in Table 11A, the opinion of probable project cost for this option is $8.5M. Optional Design Consideration "B" - under this scenario Pump Station No. 1 (PS 1) and PS 3 will be eliminated from the initial Phase I, Alternative 2 project. A previously noted in Optional Design Consideration "A ", PS 3 can be constructed at a future date with minimal impact to providing wastewater service on the corridor. Similarly, the service area of PS 1 is also minimal with respect to the cost benefit associated with its construction, serving only a projected 35,000 GPD, or 5.3% of the total 660,000 GPD estimated flow. PS 1 can also be constructed at a future date to accommodate growth in the corridor without detrimental impact to the recommended Phase I, Alternative 2 system. Figure 3.313 provides a schematic of Optional Design Consideration "B". As shown in Table 1113, the opinion of probable project cost for this option is $6.7M. For additional cost benefit, this scenario also reduces the cost of the proposed collection system by eliminating 1,200 linear feet of 8 -inch gravity sewer that would be tributary to PS 1. The estimated reduction in costs for the collection system portion of the project is approximately $0.5M. Refer to Figure 3.7, which details the gravity sewer system that would be eliminated under this scenario. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -18- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis Tables 11A and 11B provide opinions of probable project costs for Optional Design Consideration "A" and Optional Design Consideration "B" respectively: Table 11A - Phase I, Alternative 2 - Opinion of Probable Project Cost Optional Design Consideration "A" Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $135,000.00 LS $135,000 2 8" Force Main C900 PVC 25,000 LF $65.00 LF $1,625,000 3 8" Force Main DIP 2,000 LF $85.00 LF $170,000 4 4" Force Main C900 PVC 7,000 LF $50.00 LF $350,000 5 4" Force Main DIP 1,000 LF $70.00 LF $70,000 6 Bore and Jack 16" Diameter Steel Encasement 500 LF $250.00 LF $125,000 7 8" DI Carrier Pipe 500 LF $95.00 LF $47,500 8 12" Directional Drill HDPE Class 200 SDR9 1,500 LF $300.00 LF $450,000 9 8" Directional Drill HDPE Class 200 SDR9 500 LF $275.00 LF $137,500 10 Air Release Valve in Manhole 6 EA $5,000.00 EA $30,000 11 8" Gate Valves 8 EA $1,000.00 EA $8,000 12 DI Restrained Fittings 12,000 LBS $7.00 LBS $84,000 13 PS 1 Wastewater Pump Station 1 LS $800,000.00 LS $800,000 14 PS 2 Wastewater Pump Station 1 LS $1,500,000.00 LS $1,500,000 15 Remove and Replace Curb and Gutter 200 LF $30.00 LF $6,000 16 Remove and Replace Gravel Drives 500 SY $10.00 SY $5,000 17 Remove and Replace Asphalt Drives 800 SY $40.00 SY $32,000 18 Remove and Replace Concrete Drive 500 LF $80.00 LF $40,000 19 Silt Fence 8,000 LF $3.00 LF $24,000 20 Check Dam 60 EA $350.00 EA $21,000 21 Straw with Net Liner (Min. 8' wide roll) 5,500 LF $2.00 LF $11,000 22 Undercut Excavation w /Select Material In- 1,500 CY $15.00 CY $22,500 23 Stabilization Stone (6" Depth) 6,000 LF $3.00 LF $18,000 Subtotal $5,711,500 Contingency $1,713,450 Technical Fees $856,725 Land /Easement Acquisition $200,000 Total Opinion of Probable Project Cost $8,481,675 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -19- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 11B - Phase I, Alternative 2 - Opinion of Probable Project Cost Optional Design Consideration 'B" Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $125,000.00 LS $130,000 2 8" Force Main C900 PVC 25,000 LF $65.00 LF $1,625,000 3 8" Force Main DIP 2,000 LF $85.00 LF $170,000 4 Bore and Jack 16" Diameter Steel Encasement 500 LF $250.00 LF $125,000 5 8" DI Carrier Pipe 500 LF $95.00 LF $47,500 6 12" Directional Drill HDPE Class 200 SDR9 1,500 LF $300.00 LF $450,000 7 8" Directional Drill HDPE Class 200 SDR9 500 LF $275.00 LF $137,500 8 Air Release Valve in Manhole 6 EA $5,000.00 EA $30,000 9 8" Gate Valves 8 EA $1,000.00 EA $8,000 10 DI Restrained Fittings 12,000 LBS $7.00 LBS $84,000 11 PS 2 Wastewater Pump Station 1 LS $1,500,000.00 LS $1,500,000 12 Remove and Replace Curb and Gutter 200 LF $30.00 LF $6,000 13 Remove and Replace Gravel Drives 500 SY $10.00 SY $5,000 14 Remove and Replace Asphalt Drives 800 SY $40.00 SY $32,000 15 Remove and Replace Concrete Drive 500 LF $80.00 LF $40,000 16 Silt Fence 8,000 LF $3.00 LF $24,000 17 Check Dam 60 EA $350.00 EA $21,000 18 Straw with Net Liner (Min. 8' wide roll) 5,500 LF $2.00 LF $11,000 19 Undercut Excavation w /Select Material In -place 1,500 CY $15.00 CY $22,500 20 Stabilization Stone (6" Depth) 6,000 LF $3.00 LF $18,000 Subtotal $4,486,500 Contingency $1,345,950 Technical Fees $672,975 Land /Easement Acquisition $200,000 Total Opinion of Probable Project Cost $6,705,425 Recommended Phase I, Alternative 2 is estimated at $10.4M. Therefore, implementation of Optional Design Consideration "A" at $8.5M will result in a reduction in total estimated costs of $1.9M. Similarly, Optional Design Consideration "B" at $6.7M will provide a reduction in total estimated costs of $3.7M. Optional Design Consideration "B" provides an additional $0.5M in cost reduction by eliminating 1,200 feet of gravity sewer main tributary to PS 1. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -20- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis 3.6 PHASE II - ALTERNATIVES ANALYSIS FOR PUMP STATION & FORCE MAIN SYSTEM As previously noted, the alternatives evaluated in this document are based on a phased approach, providing for a system designed to accommodate intermediate needs (Phase I) of the corridor and expandable to meet the long -term 2040 needs (Phase II) identified in Table 1 of this TM. Section 3.4 of this TM provided a recommended alternative for the Phase I to meet the initial, intermediate wastewater needs of the corridor based on the Most Likely scenario. Phase II evaluations are based on 2040 demands and incorporates the recommended Phase I infrastructure as the 'backbone' system for both the Most Likely and Optimistic scenarios. Various Phase II configurations were considered to include paralleling the recommended Phase I configuration such that all wastewater flow generated in the corridor is discharged to PS 12. Another primary configuration entailed a new force main to the Chair Road PS (CRPS), which would allow for wastewater flow generated in the corridor to be accommodated by both CRPS and PS 12. After review of these configurations and consultations with New Hanover County and CFPUA, it was determined that Phase II would be focused on a new force main connection to the CRPS. The advantages of this configuration include: • The ability to manage and /or balance daily flows and capacities from the corridor via two independent pump stations in the CFPUA system. Increased flexibility with respect to event management. Under this configuration, a portion of wastewater flow could be directed either north to CRPS or south to PS 12 in an emergency or maintenance event. While complete, 100% peak redundancy would not be achieved, the option to manage flows via the alternate pump station connection points would be highly beneficial to CFPUA staff during such events. Subsequently, the Phase II alternatives presented herein are based on a second force main to CRPS in order to meet the 2040 wastewater needs of the corridor. Similar to Phase I, pump station and force main sizing were evaluated based on the average daily flow (ADF) identified in Table 1 and Table 1A for the Most Likely and Optimistic scenarios. Table 12 provides the pumping capacity based on the NCDEQ Minimum Design Criteria established: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -21- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 12 - Phase II Pumping Capacity Minimum Design Criteria Pumping Station Total Average Daily Flow (GPD) Peak Hourly Factor (PHF) Minimum Peak Pump Rate (GPM) ML OP ML OP PS 1 66,000 97,000 2.5 115 170 PS 2* 615,000 946,000 2.5 1070 1645 PS 3 45,000 54,000 2.5 80 95 *PS 2 ADF includes the ADF from PS 1. Based on the required capacities noted in Table 12, hydraulic modeling was conducted to determine the necessary pipe parallelisms, new pipe construction, and pump station upgrades required when compared to the Phase I recommended system. Results of the hydraulic modeling yielded the following infrastructure requirements for Phase II (See Figure 3.4): • Pumps would require replacement for increased capacity in PS 1, PS 2, and PS 3. Duplex configurations would remain for PS 1 and PS 3, however, PS 2 would be revised from a duplex arrangement recommended in Phase I to a triplex arrangement for Phase II. • A new parallel force main would be required from PS 2, south along US Highway 421 to the approximate intersection with the existing Duke Energy Transmission easement. • A new force main would be required parallel to the Duke Energy Transmission easement. Easement acquisition is anticipated parallel to the Duke easement as current Duke policies would not provide for construction of the force main within the transmission easement boundary. • A new 4,000 linear feet directional drill would be required under the NE Cape Fear River to connect to the CRPS. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -22- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis PHASE II — MOST LIKELY SCENARIO For the Phase II Most Likely scenario, Table 13 provides hydraulic modeling results for potential pipe sizes. Table 13 —Hydraulic Results Phase H Most Likely Under this alternative, wastewater flow would be hydraulically split between the CRPS and PS 12, with approximately 55% of flow conveyed to CRPS and approximately 45% conveyed to PS 12. Additionally, upgrades to pumps and motor horsepower for each pump station would also be necessary to meet the projected Phase II wastewater flows. Table 14 provides a summary of the proposed pump/horsepower upgrades required for this configuration. Table 14 — Phase H Most Likely Pump Station Design Recommendations US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -23- Parallel Pipe Phase I Phase II Total Parallel Pipe Force Main Pipe or New Pipe Pipe Force Main or New Pipe Segment Diameter Diameter Flow Required Required PS 1 to PS 2 4" 115 GPM No N/A PS 2 to Duke Energy 8 1070 GPM Parallel Pipe 8" Easement at US 421 US 421/Duke Energy Easement to Chair N/A 580 GPM New Pipe 8" Road PS US 421 /Duke Energy 8" 490 GPM No N/A Easement to PS 3 PS 3 to PS 12 8" 80 GPM No N/A (Manifold Connection) Existing 8 -Inch HDPE 8" Single 570 GPM No N/A under NE Cape Fear River 8" Parallel 285 GPM Each No N/A Under this alternative, wastewater flow would be hydraulically split between the CRPS and PS 12, with approximately 55% of flow conveyed to CRPS and approximately 45% conveyed to PS 12. Additionally, upgrades to pumps and motor horsepower for each pump station would also be necessary to meet the projected Phase II wastewater flows. Table 14 provides a summary of the proposed pump/horsepower upgrades required for this configuration. Table 14 — Phase H Most Likely Pump Station Design Recommendations US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -23- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis The opinion of probable project cost for the Phase II Most Likely scenario is provided in Table 15 as follows: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -24- Recommended Pumping Duplex Pump Triplex Pump Design Peak Pump Head Station Motor Size Motor Size Rate PS 1 115 GPM 78 feet 25 HP N/A PS 2 1070 GPM 169 feet 150 HP 100 HP PS 3 80 GPM 73 feet 20 HP N/A The opinion of probable project cost for the Phase II Most Likely scenario is provided in Table 15 as follows: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -24- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 15 — Phase II Opinion of Probable Project Cost, Most Likely Scenario Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $75,000.00 LS $75,000 2 8" Force Main C900 PVC 17,000 LF $65.00 LF $1,105,000 3 8" Force Main DIP 1,000 LF $85.00 LF $85,000 4 Bore and Jack 16" Diameter Steel Encasement 500 LF $250.00 LF $125,000 5 8" DI Carrier Pipe 500 LF $95.00 LF $47,500 6 Directional Drill HDPE Class 200 SDR9 4,000 LF $400.00 LF $1,600,000 7 Air Release Valve in Manhole 3 EA $5,000.00 EA $15,000 8 8" Gate Valves 4 EA $1,000.00 EA $4,000 9 DI Restrained Fittings 10,000 LBS $7.00 LBS $70,000 10 PS 1 Wastewater Pump Station Upgrades 1 LS $0.00 LS $0 11 PS 2 Wastewater Pump Station Upgrades 1 LS $100,000.00 LS $100,000 12 PS 3 Wastewater Pump Station Upgrades 1 LS $50,000.00 LS $50,000 13 Remove and Replace Curb and Gutter 50 LF $30.00 LF $1,500 14 Remove and Replace Gravel Drives 50 SY $10.00 SY $500 15 Remove and Replace Asphalt Drives 50 SY $40.00 SY $2,000 16 Remove and Replace Concrete Drive 50 LF $80.00 LF $4,000 17 Silt Fence 5,000 LF $3.00 LF $15,000 18 Check Dam 25 EA $350.00 EA $8,750 19 Straw with Net Liner (Min. 8' wide roll) 1,500 LF $2.00 LF $3,000 20 Undercut Excavation w /Select Material In -place 1,500 CY $15.00 CY $22,500 21 Stabilization Stone (6" Depth) 3,000 LF $3.00 LF $9,000 Subtotal $3,342,750 Contingency $1,002,825 Technical Fees $501,413 Land /Easement Acquisition $200,000 Total Opinion of Probable Project Cost $5,046,988 PHASE II — OPTIMISTIC SCENARIO For the Phase II Optimistic scenario, Table 16 provides hydraulic modeling results for potential pipe sizes. Figure 3.5 provides a schematic of the Phase II Optimistic scenario. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -25- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 16 —Hydraulic Results Phase H Optimistic Under this alternative, flow would be hydraulically split between the CRPS and PS 12, with approximately 75% of flow conveyed to CRPS and approximately 25% conveyed to PS 12. Similar to the Most Likely scenario, upgrades to pumps and motor horsepower for each pump station would be necessary to meet the projected Phase II wastewater flows. Table 17 provides a summary of the proposed pump/horsepower upgrades required for this configuration. Table 17 — Phase H Optimistic Pump Station Design Recommendations Pumping Station Recommended Design Peak Pump Rate Total Dynamic Head Duplex Pump Motor Size Parallel Pipe or PS 1 Phase I Phase II Total Parallel Pipe N/A PS 2 1645 GPM 147 feet 150 HP New Pipe Force Main Pipe Segment Pipe Force Main or New Pipe N/A Diameter Diameter Flow Required Required PS 1 to PS 2 4" 170 GPM No N/A PS 2 to Duke Energy Easement 8" 1645 GPM Parallel Pipe 10" at US 421 US 421/Duke Energy Easement N/A 1235 GPM New Pipe 12" to Chair Road PS US 421/Duke Energy Easement 8" 440 GPM No N/A to PS 3 (Manifold Connection) PS 3 to PS 12 8" 80 GPM No N/A Existing 8 -Inch HDPE under 8" Single 535 GPM No N/A 8" 268 GPM Each No N/A NE Cape Fear River Parallel Under this alternative, flow would be hydraulically split between the CRPS and PS 12, with approximately 75% of flow conveyed to CRPS and approximately 25% conveyed to PS 12. Similar to the Most Likely scenario, upgrades to pumps and motor horsepower for each pump station would be necessary to meet the projected Phase II wastewater flows. Table 17 provides a summary of the proposed pump/horsepower upgrades required for this configuration. Table 17 — Phase H Optimistic Pump Station Design Recommendations Pumping Station Recommended Design Peak Pump Rate Total Dynamic Head Duplex Pump Motor Size Triplex Pump Motor Size PS 1 170 GPM 153 feet 40 HP N/A PS 2 1645 GPM 147 feet 150 HP 75 HP ** PS 3 95 GPM 64 feet 20 HP N/A * *In comparison to Phase II -Most Likely scenario, the triplex motor size configuration for this scenario results in a slightly smaller horsepower required. This is a result of the increased pipe sizes and hydraulic balances achieved between the CRPS and PS 12 flow conveyance split. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -26- Technical Memorandum 3.0 v McKfN4&CREED Hazen Wastewater Infrastructure Alternatives Analysis The opinion of probable project cost for the Phase II Optimistic scenario is provided in Table 18: Table 18 - Phase II Opinion of Probable Project Cost, Optimistic Scenario Item Description Quantity Unit Price Total Cost 1 Mobilization (Less than 2% of Bid) 1 LS $100,000.00 LS $100,000 2 10" Force Main C900 PVC 8,000 LF $85.00 LF $680,000 3 10" Force Main DIP 1,000 LF $105.00 LF $105,000 4 12" Force Main C900 PVC 8,000 LF $100.00 LF $800,000 5 12" Force Main DIP 1,000 LF $125.00 LF $125,000 6 Bore and Jack 20" Diameter Steel Encasement 500 LF $300.00 LF $150,000 7 10" DI Carrier Pipe 500 LF $110.00 LF $55,000 8 Directional Drill HDPE Class 200 SDR9 4,000 LF $400.00 LF $1,600,000 9 Air Release Valve in Manhole 3 EA $5,000.00 EA $15,000 10 8" Gate Valves 4 EA $1,000.00 EA $4,000 11 DI Restrained Fittings 12,000 LBS $7.00 LBS $84,000 12 PS 1 Wastewater Pump Station Upgrades 1 LS $0.00 LS $0 13 PS 2 Wastewater Pump Station Upgrades 1 LS $125,000.00 LS $125,000 14 PS 3 Wastewater Pump Station Upgrades 1 LS $75,000.00 LS $75,000 15 Remove and Replace Curb and Gutter 50 LF $30.00 LF $1,500 16 Remove and Replace Gravel Drives 50 SY $10.00 SY $500 17 Remove and Replace Asphalt Drives 50 SY $40.00 SY $2,000 18 Remove and Replace Concrete Drive 50 LF $80.00 LF $4,000 19 Silt Fence 5,000 LF $3.00 LF $15,000 20 Check Dam 25 EA $350.00 EA $8,750 21 Straw with Net Liner (Min. 8' wide roll) 1,500 LF $2.00 LF $3,000 22 Undercut Excavation w /Select Material 1,500 CY $15.00 CY $22,500 23 Stabilization Stone (6" Depth) 3,000 LF $3.00 LF $9,000 Subtotal $3,984,250 Contingency $1,195,275 Technical Fees $597,638 Land /Easement Acquisition $200,000 Total Opinion of Probable Project Cost $5,977,163 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -27- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis 3.7 EVENT AND INCIDENT MANAGEMENT The US Highway 421 corridor in New Hanover County is generally separated from the primary CFPUA system and service area by the NE Cape Fear River and the Cape Fear River. Subsequently, management of events, such as maintenance or emergencies, may present challenges from an operational perspective as alternative means of redirecting wastewater flow to other areas of the CFPUA would be limited. Based upon the proposed configurations presented in this document, the following is a discussion of event /incident management for each phase. Phase I The infrastructure configuration presented for the Phase I system does not provide an alternative route for redirecting flow to other parts of the CFPUA system for event management, as it generally entails a single force main connection to PS 12. However, the following is recommended to improve operational flexibility during such an event: • Force Main In -Line Valves - In -line valves can be strategically located along the proposed force main. In the event of a pipe failure, sections of the force main can be isolated to expedite repair and minimize sanitary sewer spills. Tee Stub -Outs - Stub -outs with tees and valves can be strategically located to allow for bypass of a pipe section in the event of pipe failure. The section of force main could be isolated and bypassed during repairs. Construct By -Pass at PS 12 - The proposed configuration will discharge directly to PS 12, where it will be collected and re- pumped. It is recommended that piping and valving be installed around PS 12 to allow the US Highway 421 flow to bypass PS 12 and utilize the PS 12 20 -inch force main. While some reduction in pumping capacity from the 421 corridor pump stations would occur, this scenario would provide an excellent means of maintaining service to US 421 in the event that PS 12 is off -line or unable to operate. Table 19 provides hydraulic results of the potential PS 12 bypass operation: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -28- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 19— Hydraulic Results of Bypassing Pump Station 12 'Refer to Appendix A for the "Duke Energy Sutton Plant Leachate Conveyance System Technical Memorandum". Phase II Phase II provides a significant benefit with respect to event management as the proposed configuration will include two primary discharge /connection points to the CFPUA wastewater system at CRPS and PS 12. In an emergency or maintenance event, flow can be directed solely to either CRPS or PS 12 with valved connections, which will provide excellent event management flexibility for CFPUA staff. Additionally, the Phase I approach to in -line valves and stub -out tees is recommended for Phase II. It would also be recommended that strategic interconnections be made between parallel pipe segments where feasible. In the event of pipe failure, the flow could temporarily be redirected to the adjacent parallel force main until such time repairs or maintenance is completed. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -29- Actual Peak Pump Rate Bypassing Recommended Design PS12 Pumping Station Peak Pump Rate PS 12 Off PS 12 Pumping PS 1 80 GPM 80 GPM 80 GPM PS 2 535 GPM 496 GPM 479 GPM PS 3 80 GPM 45 GPM 18 GPM Duke Leachate 325 GPM 249 GPM 210 GPM Pump Station" 'Refer to Appendix A for the "Duke Energy Sutton Plant Leachate Conveyance System Technical Memorandum". Phase II Phase II provides a significant benefit with respect to event management as the proposed configuration will include two primary discharge /connection points to the CFPUA wastewater system at CRPS and PS 12. In an emergency or maintenance event, flow can be directed solely to either CRPS or PS 12 with valved connections, which will provide excellent event management flexibility for CFPUA staff. Additionally, the Phase I approach to in -line valves and stub -out tees is recommended for Phase II. It would also be recommended that strategic interconnections be made between parallel pipe segments where feasible. In the event of pipe failure, the flow could temporarily be redirected to the adjacent parallel force main until such time repairs or maintenance is completed. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -29- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis 3.8 ALTERNATIVES ANALYSIS - COLLECTION SYSTEM APPROACH In order to provide service to the primary development zones, a collection system will be required. The collection system will provide a point of access to the individual properties within the project area and will convey the wastewater collected to the pump station and force main systems recommended previously in this memorandum. For the purposes of this study, two primary collection system alternatives were evaluated and as previously noted, were focused on Zones 1 and 2, as over 90% of wastewater flow generation is projected in these areas: Collection System Alternative 1- Conventional Gravity Sewer System Collection Approach 1 involves a conventional gravity sewer system utilizing sewer mains constructed at slope and corresponding manholes. Refer to Figure 3.6 for a schematic of the proposed gravity sewer collection system. Advantages and disadvantages of Approach 1 are: Advantages Gravity systems historically provide the most flexible point of connection for customers as service laterals can be installed from the customer and individual pumping systems are normally not required. • Gravity sewer systems do not require electrical or utility service for either the CFPUA or the individual customer. • Conventional gravity sewer is the most common of collection systems and will be a readily recognized means of access for future customers on the corridor. Disadvantages Gravity sewer collection systems are generally the most expensive type of collection system constructed when compared to low- pressure systems, headers, vacuum systems, etc. This is primarily due to depth of excavation, shoring, dewatering, equipment, and manpower, and time of construction. Significant easement will be required to construct and maintain the sewer system. It is anticipated that a 40 -50 foot wide easement would be required for construction and a 30 -40 foot wide permanent easement would be required for maintenance. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -30- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis In the 421 corridor, the seasonal water table is very shallow and significant dewatering is anticipated, which will add significant cost to construction of such a system. In areas of large, undeveloped tracts, construction of gravity sewer ahead of development does not always coincide with the pattern(s) of development that actually occurs and additional gravity sewer is often required. Pump stations that collect wastewater from gravity sewer systems must be designed and constructed at corresponding depths to accommodate the gravity inflow, which can increase overall project costs Given the significant expense associated with construction of the gravity sewer system, it is recommended that the pipe diameter be sized to meet the 2040 needs. Based on hydraulic calculations, a combination of 8 -inch and 12 -inch diameter gravity sewer main will be required to meet the 2040 demands (Figure 3.6 provides the location and sizing of the proposed gravity mains). The opinion of probable project cost for Collection System Alternative 1 is provided in Table 20: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -31- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 20 - Opinion of Probable Cost Collection System Alternative 1 Gravity Sewer Item Description Quantity Unit Price Total Cost 1 Mobilization (less than 2% of bid) 1 LS $100,000 $100,000 2 12" PVC Sanitary Sewer c. 8' -10' Depth 800 LF $200 $160,000 f. 14' - 16' De th 3,100 LF $250 $775,000 h. 18'- 20' Depth 5,000 LF $350 $1,750,000 3 12" DI Sanitary Sewer c. 8'- 10' Depth 100 LF $225 $22,500 f. 14'- 16' Depth 200 LF $275 $55,000 h. 18'- 20' De th 500 LF $375 $187,500 4 8" PVC Sanitary Sewer c. 8 - 10' De th 100 LF $185 $18,500 f. 14'- 16' Depth 800 LF $225 $180,000 h. 18'- 20' De th 100 LF $300 $30,000 5 8" DI Sanitary Sewer c. 8' -10' De th 50 LF $200 $10,000 f. 14'- 16' Depth 100 LF $250 $25,000 h. 18'- 20' De th 50 LF $325 $16,250 6 4' Diameter Precast S.S. Manhole c. 8'- 10' Depth 11 EA $7,000 $77,000 f. 14'- 16' Depth 10 EA $12,000 $120,000 h. 18'- 20' De th 4 EA $15,000 $60,000 7 Manhole Frames and Covers 25 EA $1,500 $37,500 8 Bore and Jack 24" Diameter Steel Encasement 1000 LF $500 $500,000 9 12" DI Carrier Pipe 1000 LF $350 $350,000 10 Silt Fence 10,000 LF $3 $30,000 11 Check Dam 25 EA $350 $8,750 12 Straw with Net Liner (Min. 8' wide roll) 2,500 LF $2 $5,000 13 Undercut Excavation w /Select Material 20,000 CY $30 $600,000 14 Stabilization Stone (6" Depth) 40,000 LF $5 $200,000 Subtotal $5,318,000 Contingency $1,329,500 Technical Fees $797,700 Land /Easement Acquisition $250,000 Total Opinion of Probable Project Cost $7,445,200 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -32- v MCMM &CREED Technical Memorandum 3.0 Hazen Wastewater Infrastructure Alternatives Analysis Collection System Alternative 2 - Force Main Collection Header System Collection System Approach 2 involves installation of a force main collection header system, which provides access to individual properties via a pumped connection. Under this alternative, customers would install a small pumping system sized to meet their specific capacity and discharge to the force main header, which will convey wastewater to the primary pump station and force main system previously recommended in this memorandum. Refer to Figure 3.7 for a schematic of the proposed force main collection header system. Advantages and disadvantages of Approach 2 are: Advantages • A force main header system will be less expensive than a conventional gravity sewer system, as the pipelines can be constructed at a minimal depth (3 feet below grade). • The time of construction will be considerably less when compared to a conventional gravity system. • Given the small diameter and relative ease of construction, the force main header can be constructed to accommodate initial Phase I capacities and then paralleled at a future date to coincide with growth. • Routing for a force main header has more flexibility as it does not require straight pipe installation and manholes necessary with conventional gravity sewer systems. • Force main headers could potentially provide for shallower pump station construction resulting in reduced project costs. • Easements will be required for the force main header installation; however, it can typically be less than that of conventional gravity sewer. The width of the easement will typically be 30 -40 feet for construction and 20 -30 feet for a permanent easement. Disadvantages Requires customers to install individual pumping systems to connect to the force main header. Not as common for collection systems as conventional gravity sewer. Low velocities in header will likely require additional maintenance and flushing by CFPUA personnel. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -33- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Given the relative ease to parallel the force main header piping for future flows, it is recommended that the initial header piping be based on the Phase I capacities and then paralleled as needed to meet future growth. Additionally, it may be beneficial to install the header system for Phase I and then install a gravity sewer system for Phase II to coincide with development patterns and actual wastewater flow; however such decisions can be evaluated prior to construction of Phase II infrastructure to best suit the system requirements. The following Table 21 provides results of hydraulic evaluations for the proposed header piping for both the Phase I and Phase II Most Likely scenario: Table 21— Collection System Alternative 2 Force Main Header Hydraulic Results (Most Likely) Based on hydraulic calculations, a 4 -inch dimeter force main has been sized to meet the initial Phase I demands in Zone 1, which would be paralleled with an additional 4 -inch main for Most Likely 2040 flows. Zone 2 will require a 6 -inch main for Phase I and would be paralleled with an additional 6- inchmain to meet Most Likely 2040 flows. It is noted that a 1,200 foot segment of fl- inch gravity sewer is included for the isolated area to be served by PS 1 in lieu of the header piping for this alternative. Figure 3.7 provides the location and sizing of the proposed force main collection header and the 8 -inch gravity sewer. The opinion of probable project cost for Collection System Alternative 2 is provided in Table 22: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -34- Phase I Phase I Phase I Force Phase II Phase II Phase II Service Most Likely Peak Main Most Likely Peak Parallel Force Area ADF Flow Diameter ADF Flow Main Diameter Zone 1 75,000 GPD 130 GPM 4" 150,000 GPD 260 GPM 4" Zone 2 155,000 GPD 270 GPM 6" 310,000 GPD 540 GPM 6" Based on hydraulic calculations, a 4 -inch dimeter force main has been sized to meet the initial Phase I demands in Zone 1, which would be paralleled with an additional 4 -inch main for Most Likely 2040 flows. Zone 2 will require a 6 -inch main for Phase I and would be paralleled with an additional 6- inchmain to meet Most Likely 2040 flows. It is noted that a 1,200 foot segment of fl- inch gravity sewer is included for the isolated area to be served by PS 1 in lieu of the header piping for this alternative. Figure 3.7 provides the location and sizing of the proposed force main collection header and the 8 -inch gravity sewer. The opinion of probable project cost for Collection System Alternative 2 is provided in Table 22: US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -34- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis Table 22 - Opinion of Probable Cost for Alternative 2 Force Main Collection Header Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $50,000 LS $50,000 2 6" Force Main C900 PVC 5,000 LF $60 LF $300,000 3 6" Force Main DIP 1,000 LF $80 LF $80,000 4 4" Force Main C900 PVC 300 LF $55 LF $16,500 5 4" Force Main DIP 500 LF $75 LF $37,500 6 Bore and Jack 16" Diameter Steel Encasement 500 LF $300 LF $150,000 7 6" or 4" DI Carrier Pipe 500 LF $200 LF $100,000 8 Directional Drill HDPE Class 200 SDR9 500 LF $300 LF $150,000 9 Air Release Valve in Manhole 3 EA $5,000 EA $15,000 10 4" or 6" Gate Valves 4 EA $900 EA $3,600 11 DI Restrained Fittings 8,500 LBS $7 LBS $59,500 12 Remove and Replace Curb and Gutter 100 LF $30 LF $3,000 13 Remove and Replace Gravel Drives 100 SY $10 SY $1,000 14 Remove and Replace Asphalt Drives 100 SY $40 SY $4,000 15 Remove and Replace Concrete Drive 100 LF $80 LF $8,000 16 Silt Fence 2,500 LF $3 LF $7,500 17 Check Dam 15 EA $350 EA $5,250 18 Straw with Net Liner (Min 8' wide roll) 1,000 LF $2 LF $2,000 19 Undercut Excavation w /Select Material 1,000 CY $15 CY $15,000 20 Stabilization Stone (6" Depth) 1,500 LF $3 LF $4,500 Gravity Sewer for PS 1 Service Area (See Figure 3.71 21 8" PVC Sanitary Sewer (10' -12' Depth) 900 LF $250 LF $225,000 22 4' Diameter Precast S.S. Manhole (10' -12' Depth) 4 EA $12,000 EA $48,000 23 Manhole Frames and Covers 4 EA $1,500 EA $6,000 23 Bore and Jack 24" Diameter Steel Encasement 300 LF $300 LF $90,000 24 8" DI Sanitary Sewer Carrier Pipe 300 LF $250 LF $75,000 Subtotal $1,456,350 Contingency $436,905 Technical Fees $218,453 Land /Easement Acquisition $250,000 Total Opinion of Probable Project Cost $2,361,708 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -35- Technical Memorandum 3.0 v MCMM&CREED Hazen Wastewater Infrastructure Alternatives Analysis Collection System Summary Recommendations The Alternative 2 Force Main Collection Header System and PS 1 gravity sewer main is considerably less expensive at $2.4M when compared to $7.5M for the Alternative 1 Conventional Gravity Sewer System. Additionally, it has a shorter construction timeline and provides flexibility for expansion as wastewater flow increases in the corridor. Therefore, it is recommended that CFPUA and New Hanover County consider implementation of Collection System Alternative 2 for the Phase I wastewater infrastructure project. 3.9 PREFERRED ALTERNATIVES In order to provide public wastewater service to the US Highway 421 corridor for the projected demands, a number of wastewater infrastructure alternatives were evaluated. The alternatives were developed to provide public wastewater service and access utilizing existing CFPUA infrastructure for conveyance and treatment, which will be accomplished at the Northside WWTP. For the purposes of this summary, the preferred alternatives have been limited to Phase I only. Table 23 provides a summary of the cost opinions for the Phase I alternatives considered. Table 23 — Phase I - Summary of Alternative Opinions of Probable Project Cost PUMP STATION AND FORCE MAIN ALTERNATIVES Alternative Description Total Cost 1 Three Pump Stations and Discharge to Chair Road PS $10.4M 2 Three Pump Stations and Discharge to Pump Station 12 $9.7M Optional Design PS 1 and PS 2 Discharge to Pump Station 12. PS 3 Consideration „A„ eliminated from the initial Phase I Alternative 2 project $8.5M Optional Design PS 2 Discharges to Pump Station 12. PS 1 and PS 3 Consideration "B' eliminated from the initial Phase I Alternative 2 project $6.7M US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -36- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis COLLECTION SYSTEM ALTERNATIVES Alternative Description Total Cost 1 Conventional Gravity Sewer System $75M 2 Force Main Collection Header System $2.4M Optional Design Consideration 'B" Eliminates 1,200 LF of 8 -inch Gravity Sewer System Tributary to PS 1 $1.9M PHASE I - SUMMARY OF POTENTIAL ALTERNATIVES Preferred Optional Design Optional Design Description Alternative Consideration Consideration Total Cost "A" "B" Alternative 2 - Pump Stations Discharge to PS 12 $9.7M $85M $6.7M Alternative 2 - Force Main Collection Header System $2.4M $2.4M $1.9M Total Phase I Alternatives Opinion of Probable $12.1M $10.9M $8.6M Project Cost The Scope of Work for this PER stipulated that alternatives be focused on providing service to all developable areas identified by New Hanover County in the corridor. Consequently, the Preferred Alternative cost of $12.1M noted above meets those criteria. It is noted that the County may elect to construct Optional Design Consideration "A" or Optional Design Consideration "B" in lieu of the Preferred Alternative based on budgetary limitations or other constraints. Implementation of either option will not hinder expansion or additions to the system at a future date. 3.10 PROPOSED DUKE COAL ASH LANDFILL LEACHATE The CFPUA and Duke Energy have entered into a contract to provide for the development of a Technical Memorandum to evaluate conveyance infrastructure necessary to accommodate leachate generated from the proposed coal ash landfills near the Sutton Plant on US Highway 421. This Technical Memorandum has been included as Appendix A of this report, which recommends that leachate generated be conveyed via pump station and force main to CFPUA PS 12. The estimated cost for the Duke Leachate Pump Station and Force Main is $5.7M to 6.OM. The proposed coal ash landfill will have two (2) 500,000 gallon storage tanks and an estimated daily peak flow of 186,000 GPD. Construction of the landfill is scheduled for completion by the US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -37- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis end of 2016 and is projected to have a 12 -year life span. The storage tanks will provide significant flexibility for Duke and CFPUA for the management and conveyance of leachate to the CFPUA system by allowing wastewater to be pumped during off -peak hours. Given the projected 12 -year life span of the landfill, the recommended Phase I force main size of 8 -inch diameter was evaluated in parallel with the proposed CFPUA system. A summary of operating conditions with the proposed leachate pumping station in operation is provided in Table 25. Table 25 — Duke Leachate System Hydraulic Operating Conditions As indicated in Table 25, a reduction in available peak pump rate would occur with the proposed Phase I system operating in parallel with the Duke Leachate PS. However, the available pumping capacities would be capable of providing a peaking factor of 1.4 to 1.6 during such parallel operations. Additionally, the availability of the leachate storage tanks and the minimal frequency of initial pumping operations for the Phase I system would reduce the likelihood of extended parallel operation during the 12 -year life span of the landfill. As a design consideration, it is recommended that SCADA /telemetry capability be provided at each pump station such that pumping operations can be optimized and managed during the operation of the Duke Energy leachate conveyance system. In the event that Duke Energy does not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -38- Pump Rate in Parallel Proposed Pumping Resultant Peak Factor Design Pump Rate Operation with Duke Station in Parallel Operation Leachate PS PS 2 (Phase I) 535 GPM 300 GPM 1.4 Peak Factor Duke Leachate PS 325 GPM 325 GPM N/A PS 3 (Phase I) 80 GPM 50 GPM 1.6 Peak Factor As indicated in Table 25, a reduction in available peak pump rate would occur with the proposed Phase I system operating in parallel with the Duke Leachate PS. However, the available pumping capacities would be capable of providing a peaking factor of 1.4 to 1.6 during such parallel operations. Additionally, the availability of the leachate storage tanks and the minimal frequency of initial pumping operations for the Phase I system would reduce the likelihood of extended parallel operation during the 12 -year life span of the landfill. As a design consideration, it is recommended that SCADA /telemetry capability be provided at each pump station such that pumping operations can be optimized and managed during the operation of the Duke Energy leachate conveyance system. In the event that Duke Energy does not to construct the proposed leachate landfill pump station and force main, the recommendations of this TM with respect to force main size, wetwell size, and routing would remain as provided. While some minor reductions may be realized with motor horsepower sizing, the impact to project costs or feasibility would be negligible. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -38- Technical Memorandum 3.0 v MCMM&CREED Hazen Wastewater Infrastructure Alternatives Analysis 3.11 ANTICIPATED PERMIT REQUIREMENTS Anticipated permits for Alternative 1 and Alternative 2 are detailed in Table 26 below: Table 26 — Anticipated Permit Requirements US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -39- Alternative 1 Alternative 2 Anticipated Permit Required Chair Road PS Pump Station 12 Remarks Discharge Discharge NCDEQ Fast Track Permit for Required for the pump station, force Pump Stations & Force Mains Yes Yes main, gravity sewer and /or force main header collection system NCDEQ Erosion & Sedimentation Yes Yes Land disturbance >1 acre requires Control Permit E &SC permit NCDEQ Storm Water Management Yes Yes Land disturbance >1 acre requires Permit (Exemption Anticipated) Storm Water Management permit NCDOT Standard Encroachment Required for installation of pipeline Agreement Yes Yes within the NCDOT right of way of US 421 NCDOT Controlled Access Required for installation of pipeline Encroachment Agreement No Yes within the NCDOT right of way at I- 140 & US 421 interchange Required for impacts to Wetlands and installations under waterways. US Army Corps of Engineers Alt. 1 will require additional Permitting Yes Yes permitting for the NE Cape Fear river crossing as compared to Alt. 2 resulting in additional time and costs. Division of Coastal Management Required for installation of pipelines CAMA Major Permit Yes Yes under navigable waters in coastal counties NC Department of Administration Yes No Required for installation beneath the Approval NE Cape Fear River Required for any crossing or CSX Railroad Lease or Permit Yes Yes parallelism of a CSX owned rail right of way US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -39- Technical Memorandum 3.0 v MCMM &CREED Hazen Wastewater Infrastructure Alternatives Analysis 3.12 ANTICIPATED SCHEDULE The anticipated Phase I project schedule is provided in Table 27 below. Note that the schedule provided is inclusive of the preferred Alternative 2 - Force Main & Pump Stations and the preferred Alternative 2 - Force Main Collection Header System. Table 27 - Anticipated Project Schedule - Phase I Preferred Alternatives Item Alternative 2 Design 8 Months Permit Review & Approval 5 Months Advertise for Bids 1 Month Open Bids /Start Construction 2 Month Complete Construction (Substantial) 20 Months Total Estimated Project Timeline 36 Months" "Note that permit review time and easement /property acquisitions are highly variable and could impact the overall project timeline. 3.13 SUMMARY AND RECOMMENDATIONS To provide public wastewater service to the US Highway 421 corridor it is recommended that a combination of pump stations and wastewater force mains be constructed along the corridor to convey wastewater to the CFPUA system. The pump stations will be strategically located to provide service to the northern corridor, primarily development Zones 1 and 2, as over 90% of projected wastewater flow is expected in this area. Additionally, a collection system is recommended for construction in the proximity of Zones 1 and 2 to collect wastewater from the individual properties where development is anticipated. A force main collection header system is recommended as it provides a cost - effective approach to providing service in these areas, and flexibility for expansion to meet future growth. The force main collection header will collect and convey wastewater generated in these areas to the proposed pumping stations, where it will be conveyed to the CFPUA existing wastewater system for treatment. Figures 3.3 and 3.7 provide the location of the proposed Phase I infrastructure recommended for implementation along the US Highway 421 corridor in New Hanover County. The total estimated cost for the Phase I preferred alternatives is $12.1M and the anticipated project timeline is 36 months. END OF TECHNICAL MEMORANDUM US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -40- / CITY OF WILMINGTON V `�wM&CM= FIGURE 3.1 EXISTING UTILITIES US 421 CORRIDOR WATER AND SEWER UTILITIES NOT TO SCALE PRELIMINARY ENGINEERING REPORT `�wm&cy= FIGURE 3.2 PHASE I - ALTERNATIVE 1 US 421 CORRIDOR WATER AND SEWER UTILITIES PUMP STATION/FORCE MAIN SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE / CITY OF WILMINGTON `�wM&CM= FIGURE 3.3 PHASE I - ALTERNATIVE 2 US 421 CORRIDOR WATER AND SEWER UTILITIES PUMP STATION/FORCE MAIN SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE CITY OF WILMINGTON V `�wM&CM= FIGURE 3.3A PHASE I - ALTERNATIVE 2 US 421 CORRIDOR WATER AND SEWER UTILITIES PUMP STATION/FORCE MAIN SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE / PS 21- C.i o C SUTTON LAKE O� O O DUKE TRANSMISSION ON POWER \ go PLANT /) o - j [ OPTIONAL DESIGN CONSIDERATION "B" A. �AlZK1 4 &CREED US 421 CORRIDOR WATER AND SEWER UTILITIES PRELIMINARY ENGINEERING REPORT RAILROAD CROSSINE CFPUA DUAL 8" FORCE MAINS FIGURE 3.313 PUMP STATION/FORCE NOT TO SCALE CITY OF WILMINGTON `�wM&CM= FIGURE 3.4 PHASE II - ALTERNATIVE 1 US 421 CORRIDOR WATER AND SEWER UTILITIES PUMP STATION/FORCE MAIN SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE CITY OF WILMINGTON V `�wM&CM= FIGURE 3.5 PHASE II - ALTERNATIVE 2 US 421 CORRIDOR WATER AND SEWER UTILITIES PUMP STATION/FORCE MAIN SYSTEM PRELIMINARY ENGINEERING REPORT NOT TO SCALE o E:fs3�� w l W cn cn z O H U W W J 0 ZU j� W W CO Q cn LU n �ccn >o o d�z �W 'oo �^ 1 ,e cn w J_ V1 ~ D 00 W H o cn 0a w N z Q � a a W 22 V1 O Q W COO Oz ow W OUz N � a O J It cn w Da 0 z 0 J O z M O 0 C z0 cf) 00Lo boof F- ci O 0 o z zw0 J 0 H 0 0 0 Z � N 0O w LIJ of w O w w w z m 0 ry im- w �O -z 0° w w a' IC •1111 ►�Iii•� X11 ��� LU �. • • • • U dA' a ox z x ww A J v D � O w o� w az a z w c l aw �0 •1111 ►�Iii•� X11 ��� LU �. • • • • U dA' a ox z w J D w w� w0 w o� az a z w c aw �0 0z COO ow 0 U z CN J LU C/) w 4JA a Uva TECHNICAL MEMORANDUM 4.0 WATER INFRASTRUCTURE ALTERNATIVES ANALYSIS Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.1 INTRODUCTION & BACKGROUND The purpose of Technical Memorandum (TM) 4.0 is to provide an evaluation of water infrastructure needs to meet the projected demands along the US Highway 421 corridor in New Hanover County through the year 2040. Infrastructure needs were evaluated based on two scenarios of future development in the US Highway 421 corridor; Most Likely (ML) and Optimistic (OP). Table 1 summarizes the 2040 water demand projections for both development scenarios. Refer to TM 2.0 for more detail on the water demand projection methodology. Table 1- Summary of Projected Water Demands 2040 (gpd) Water Projected Total Flow (gpd) Most Likely Optimistic 660,000 1,000,000 4.1 GOALS The evaluation of the water system infrastructure needs considered the following goals of the County and the Authority: • Predicted water age should be reasonable to avoid significant water quality concerns. The Authority desires that the system design and operation minimize the use of flushing to achieve water quality goals. • The US Hwy 421 Corridor water system must achieve the Authority's goals for Stage 2 Disinfectants/Disinfection Byproducts Rule compliance by meeting 80% of the maximum contaminant level (64 ppb TTHMs and 48 ppb HAAS). • The water system should provide operational flexibility and event management by providing two connections from the existing water system to the 421 Corridor. • The water system shall utilize the Sweeney WTP as its source of finished water. • The water system shall meet an available fire flow goal of 1,500 gpm minimum. • Minimum water system pressure shall be 40 psi during peak hour demands. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 1 - Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.2 EXISTING FACILITIES The Sweeney Water Treatment Plant (WTP) currently has a permitted treatment capacity of 35 MGD. The plant is an advanced treatment facility with raw water ozonation, solids contact clarifiers, intermediate ozonation, biological filtration, and UV disinfection. The raw water source is the Cape Fear River, upstream of Lock and Dam Number 1. The plant produces an average of 13 MGD (based on data from May 2011 until June 2013). The Sweeney WTP currently serves the City of Wilmington and adjoining areas. The Cape Fear Public Utility Authority also owns and operates a 6 -mgd Nanofiltration plant located in the northeastern portion of New Hanover County. Currently, the Sweeney WTP and the Nanofiltration WTP serve separate water distribution systems. However, CFPUA is currently planning to install additional interconnections and merge the systems into one combined water distribution system. The Flemington System is located along the southern portion of US Hwy 421 Corridor. Until recently, the Flemington system was a groundwater system that operated separately from the other water systems. Due to concerns with groundwater contamination, a 12 -inch water line was installed across the NE Cape Fear River in 2015 in order for the CFPUA to serve the Flemington system from the Sweeney water system. Two pressure reducing valves (PRVs) were installed to maintain the current pressures in the Flemington system (60 psi). The Flemington system has an existing system average day demand of 27 gallons per minute (gpm) and a maximum day demand of 39 gpm. The peak hour demand for the Flemington system is 68 gpm and the system currently has available fire flow of 500 to 1,000 gpm at 20 psi when the tanks in the system are half full. 4.3 CORRIDOR PLANNING APPROACH Preliminary modeling results indicate that the existing 12 inch connection to the US Hwy 421 Corridor does not have sufficient capacity to meet the new water demands and the fire flow goals. As such, water system infrastructure alternatives were evaluated to provide the adequate fire flow as well as meet existing and future system demands. Alternatives for a second connection to the US Hwy 421 Corridor are further detailed in the following sections. For all of the alternatives evaluated, both growth scenarios (Most Likely and Optimistic) were evaluated. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 2 - v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn 4.4 ALTERNATIVES ANALYSIS 4.4.1. Alternative 1- New Northern Connection to US 421 Alternative 1 proposes a new connection from the existing Wrightsboro elevated storage tank to the US 421 Corridor with a new 12 -inch pipeline as shown in Figure 1. This new connection from the Wrightsboro tank would follow the proposed sewer route to the Chair Road pump station and would cross over the Northeast Cape Fear River. A 16 -inch pipeline is proposed for the northern section of US -421 and a 12 -inch pipe is proposed for the southern section of US -421. Figure 1: Alternative 1 Configuration US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 3 - Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.4.1.1. Alternative 1 - ML Demand Scenario Under the Most Likely water demand scenario, modeling indicates that the daily water demand would be met using the existing 12 -inch connection near the Sweeney WTP. Flow through the 12- inch northern connection from the Wrightsboro Tank would occur mainly during fire flows. Therefore, the 12 -inch Wrightsboro Tank connection would be expected to have elevated water age. As shown in Figure 2, water age in the 12 -inch Wrightsboro Tank connection is estimated to be greater than 96 hours. Water age at the northern end of the proposed 16 -inch line along US -421 Corridor near the Pender County Line is estimated at 24 hours. Therefore, water age is not expected to cause water quality concerns along the US -421 Corridor. However, significant flushing may be required for the 12 -inch Wrightsboro Tank connection. Along the US Hwy 421 Corridor, peak hour pressures are estimated to be 55 to 80 psi under the Most Likely water demands. At the crossing from the Wrightsboro Tank, the pressures range from 55 to 60 psi. At the connections to the US -421 pipeline, the pressure drops to between 50 to 55 psi. Figure 3 illustrates peak hour pressures along the US -421 Corridor under the Most Likely water demand scenario. For the Most Likely scenario, available fire flow vary significantly depending on location as shown in Figure 4. On the 12 -inch Wrightsboro Tank connection, available fire flow exceeds 2,500 gpm. Along the US -421 Corridor, the available fire flow ranges from 1,500 gpm to 2,500 gpm. In the Flemington area, the available fire flow is between 500 and 1,000 gpm. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 4 - v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn 421 Corridor 2040 Most Likely Water Age �a c$St3B HamB Tank � -- - I 1P Wrighls6neo Tank Harthchase Tank � yy�ville rn w I r " Sweeney _J Legend L WTP J * yR " � *1' 19af 4f Icw �i - 2.3615f n tir Figure 2: Alternative 1 Water Age for the ML Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 5 - Technical Memorandum 4.0 �MCKIM &CREED Water Infrastructure Alternatives Analysis Hazen 421 Corridor 2040 Most Likely Peak Hour Pressures -ANZ 16 A r r' ■• ■���■ Horthchase %T.nk ' ■ Legend P51 �. ■ .+off �—■— f u•woa ■ sn.wom ■ ♦ as -en ox iui K.�, ■ •6p w. OM Mast Llke Castle Hayne Ta nk ® = Wrigbtsb— Tanis a d1t rr 4 r ti^ ■■ i Sweeney NfTP l y Figure 3: Alternative 1 Peak Hour Pressures for the ML Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 6 - ly �4Y r6' �+5• +e' r -.2 +' Figure 3: Alternative 1 Peak Hour Pressures for the ML Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 6 - Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 421 corridor 2040 ` tau,a Most Likely k Available Fire Flow R 1:] D� S� Castle Hayne Tank Wrightsbom Tank, '.. K =_r Norththase Tank Y , Legend AFF at YO psi z ltt+i_ UQ ppm qi A C) ioao 0o m � awrr Gcm �` � noo aamm aeon ®��s �. 11 u� Sweeney 1 zvw oommssrN ram Vnr r,.Mlr1� Y.54D Uem ti,s `,•,rssa 'I - -^ t. ialhw N.�g 2W Mast LlkN np r +Y .5• a Il 11 I �f9Z� Figure 4: Alternative 1 Available Fire Flow for the ML Demand Scenario Stage 2 DBP compliance is a critical concern for CFPUA, especially with increasing levels of bromide in the source water. DBP compliance is an important consideration when expanding the water system to ensure that water age is managed and DBP compliance is not compromised. Historically, total trihalomethanes (TTHMs) have been the main concern for DBP compliance for CFPUA. To evaluate the impacts of these alternatives on DBP compliance, a TTHM predictor model was developed using the Wert disinfection byproduct formation tool. In general, DBP formation models can predict general trends in DBP formation, but are not typically highly accurate at reflecting actual conditions given the number of factors contributing to DBP formation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 7 - Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen The Wert model was selected since it includes a broad range of parameters such as total organic carbon (TOC), chlorine residual, bromide concentration, temperature, pH, and water age to predict TTHM formation. To check the Wert model, Hazen and Sawyer collected water quality data for the 2nd and 3rd quarters in 2012, 2013, and 2014 to represent warm season DBP formation. Hydraulic model simulations were conducted on the days of DBP sampling over that period to determine the water age at each DBP sampling site. For the six DBP sampling dates, the average variance from the Wert model predictions and the compliance samples was 39 percent. All other DBP formation models tested resulted in a variance of 50 percent or more. The water age modeled at two locations was used to estimate the TTHM concentrations for all of the scenarios included in this technical memorandum: • Northern end of the US Hwy 421 Corridor at the Pender County line • On US Hwy 421 at the connection from the Wrightsboro elevated storage tank In the Most Likely demand scenario, water age the northern end of the US -421 Corridor at the Pender County line was estimated at approximately 24 hours. Using the TTHM predictor model, TTHMs would likely be in compliance at that location with an average value of 53 µg /L which is well below the 80% goal (64 µg /L). However, at the Wrightsboro Tank connection, the estimated water age of approximately 96 hours is expected result in TTHM concentrations of 77 µg/l, with several opportunities for the concentration to be above 80 µg/l, in the warm water summer months. Therefore, flushing would be required to maintain water age below approximately 48 hours in order to maintain DBP compliance with the Stage 2 Rule. 4.4.1.2 Alternative 1 - Optimistic Demand Scenario Under the OP demand scenario, more supply would come from the Wrightsboro Tank connection as compared to the Most Likely demand scenario. However, most of the daily demand would still be meet through the existing 12 -inch connection from the Sweeney WTP. Peak hour pressures under the OP demand scenario are illustrated in Figure 6. Peak hour pressures are similar to those under the ML demand scenario, with pressures exceeding 80 psi throughout the US Hwy 421 Corridor. Pressures in the Flemington system are 48 to 59 psi. Under the OP demand scenario, available fire flow vary dramatically depending on location as shown in Figure 7, and are less than the fire flows under the Most Likely scenario. On the US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 8 - , McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn Wrightsboro Tank connection, available fire flow exceeds 2,500 gpm. However, along the US -421 Corridor, the available fire flow ranges from 500 gpm to 2,000 gpm. In the Flemington area, the available fire flow is still between 500 and 1,000 gpm. As expected, the predicted water ages for the OP scenario are much lower than the ML, as seen in Figure 5. The water age ranges from 24 to 72 hours. The highest water age is found in the Wrightsboro Tank connection. With higher demands, less flushing would be needed to maintain an acceptable water age and associated DBP concentration. 421 Corridor 2040 Optimistic _ , Water Age rz 3� Caade Hayne Tank 1. I Wdghtshoro Tank HartFichase Tank - sysvglt ro 11 y. � •d lr irn,�l:.n I t Sweeney Legend WTP J h. Wales Aq. '�'4� 1wr wlefs - 1.YWI . �• � F - Y•30iry1 `Nrl h! �MaelMn+l Chf Figure 5: Alternative 1 Water Age for the OP Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report - 9 - Technical Memorandum 4.0 �MCKIN4 &CREED Water Infrastructure Alternatives Analysis Hazen f �. 421 Corridor 2040 Optimistic Peak Hour Pressure 4 Castle Hayne Tank y! 1 s� ._Wnghtsb. Tank !! �- N!~ North Chase Tank al--'f .. fgtfLibSro —� i ..__� Legend pp+ PSI �I ■ =mPm ti`1 -�, a au. asati dk • �,�,� - Sweeney ! IV ■ 56-60P. Vnr tl. Si ,ao w, �'b0 f luau optlmlatic Figure 6: Alternative 1 Peak Hour Pressure for the OP Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -10- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen Figure 7: Alternative 1 Available Fire Flow for the OP Demand Scenario For the OP demand scenario, water age at the northern end of the US -421 Corridor at the Pender County line is estimated at approximately 24 hours. TTHMs are predicted to be in compliance at that location with an average value of 53 µg /L. At the Wrightsboro tank connection, the estimated water age of approximately 72 hours is predicted to result in an average TTHM concentration of 71 ltg /L with several opportunities for the concentration to be above 80µg/L in the warm water summer months. Therefore, flushing would be required to reduce water age and TTHM levels. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -11- 4° 421 Corridor 2040 .. r 90 gPm shy �• ",aw Optimistic Available Fire Flow Cas41e Hayne Tank t V, 74 ��, �; NVrig4ptsboro Tank �$' =_r Norththase Tank 1 - 't�.. � - -. _- .-- ~— MsEy, -..4� - _ ,, Fw•aaYS�aHa` Legend AFF @ 20 ➢si ,, . I.tu• roan `� rpm r ft ¢Yjwn 00'1 OcS00la1pOP '� a Q aoos spmroaeoo mi. �` _ � 1SOp ppm[a sOC9 q➢m Sweeney 1 I * 1oo04pmry2S�wm 1111 Vnr u K"a I "aO � iaet m +Y _..l•1/• r5• p Il 11 I �a9Z� Figure 7: Alternative 1 Available Fire Flow for the OP Demand Scenario For the OP demand scenario, water age at the northern end of the US -421 Corridor at the Pender County line is estimated at approximately 24 hours. TTHMs are predicted to be in compliance at that location with an average value of 53 µg /L. At the Wrightsboro tank connection, the estimated water age of approximately 72 hours is predicted to result in an average TTHM concentration of 71 ltg /L with several opportunities for the concentration to be above 80µg/L in the warm water summer months. Therefore, flushing would be required to reduce water age and TTHM levels. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -11- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.4.1.3. Alternative 1 Cost Opinion A preliminary cost opinion for Alternative 1 is approximately $10.35 million. The cost opinion includes 15% for engineering and design, 1.5% for survey and geotechnical, and 30% contingency. Based on recent work in the US Hwy 421 Corridor, CFPUA has reported that the water table is high in this area. The cost opinion assumes that dewatering throughout the pipeline route will be required. Alternative 1 will also require easement acquisition for the portion of the route adjacent to the existing power easement as well as potential wetlands mitigation in this area. The river crossing is based on a 20 -inch HDPE, SDR 9 pipeline (nominal ID of 15.5 inches) installed via horizontal directional drilling at 40 feet below the river bottom. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -12- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn Table 1: Capital Cost Opinion for Alternative 1 Item Description Quantity Unit Price Total Cost 1 Mobilization 1 LS $190,000 $190,000 2 Erosion Control 1 LS $410,000 $410,000 3 Traffic Control 1 LS $9,500 $9,500 4 20" HDD Crossing NE Cape Fear River 2,500 if $415 $1,037,500 5 16" C905, DR18, PVC Pipe 16,000 LF $92 $1,472,000 6 12" C900, DR18, PVC Pipe 27,400 LF $73 $2,000,200 7 20" Restrained Joint DIP, PC 250 20 LF $165 $3,300 8 16" Restrained Joint DIP, PC 250 2,000 LF $135 $270,000 9 DI Fittings 33,000 LB $4.50 $148,500 10 30"y Bore & Jack -Road 400 LF $420 $168,000 11 30"y Bore & Jack - Railroad 300 LF $530 $159,000 12 16" Gate Valve 7 EA $6,600 $46,200 13 12" Gate Valve 11 EA $2,300 $25,300 14 Fire Hydrant w/ GV & 6" DIP 31 EA $3,725 $115,475 15 Air Release Valve Assemblies w /MH 2 EA $5,500 $11,000 16 Flowable Fill (NCDOT Roads) 300 CY $110 $33,000 17 Remove & Replace Asphalt Pavement 2,750 LF $47 $129,250 18 Remove & Replace Concrete Pavement 210 SY $58 $12,180 19 Remove & Replace Driveways, Curb & Gutter, and Drainage Swales 1 LS $20,800 $20,800 20 Easement Acquisition 8 AC $30,000 $240,000 Subtotal $6,501,000 Wetlands Mitigation $385,000 Technical Fees $1,072,700 Contingencies $2,387,600 Total Opinion of Probable Project Cost $10,346,300 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -13- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.4.2. Alternative 2 - New Southern Connection to US 421 from Sweeney WTP A new southern connection to the US Hwy 421 Corridor closer to the Sweeney WTP was also evaluated. In Alternative 2, a new 12 -inch connection parallel to the existing 12 -inch would be installed from the Sweeney WTP to the Flemington area. From Flemington, a 16 -inch pipeline would be installed along US Hwy 421, and then transiting to a 12 -inch pipeline closer to the Pender County line. The length of 16 -inch line required (as compared to 12 -inch) depends on the available fire flow desired. Figure 8 illustrates the possible configurations for Alternative 2. 2a: Pipeline Configuration for 1000 gpm fire flow 2b: Pipeline Configuration for 1500 gpm fire flow Figure 8: Possible Pipeline Configurations for Alternative 2 4.4.2.1. Alternative 2 - ML Demand Scenario Figure 9 illustrates the pipeline configuration for Alternative 2a, which meets the minimum fire flow goal of 1,000 gpm. Available fire flow along the southern portion of the US Hwy 421 corridor is 2,500 gpm, and decreases to 1,000 gpm near the Pender County line. The available fire flow is approximately 500 to 1,000 gpm in the Flemington area. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -14- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn V 421 Corridor 2040 Most Likely 1000 gpm AFF ` } Wrighfshoro Tank 5 Legend �— '- AFF 24 pN . 4w,nnNa Ovm • _ � G�Nx IAN Y.W Snm mw M .[ 6rrr m WTP Figure 9: Alternative 2a Available Fire Flow for the ML Demand Scenario Figure 10 illustrates the pipeline configuration for Alternative 2b, which meets the minimum fire flow goal of 1,500 gpm. Fire flow is similar to that shown in Figure 11. Extending the 16 -inch line further north provides 1,500 gpm fire flow near the Pender County line. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -15- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 421 Corridor 2040 Most Likely 1500 gpm AFF 8 ' qa r R °3 . Nhighta6wa iank .4 ,� sV ��.•- .. iegentl -F ."D p1 L.0 even YlO p.m '.Phis egpp pprn 'mom � � sMOWm #eeW 9T . t'.PIWmb YOO9Vw nQ MM Mdy 9 5 Sweeney u SWTP ... er .. sr Figure 6 - Alternative 2b Available Fire Flow with ML Demand Scenario The Alternative 2a for the 1,000 gpm fire flow was used for the peak hour evaluation, as this configuration has the shortest section of 16 -inch pipeline. Peak hour pressures are typically 60 to 80 psi, but in the Flemington area, the peak hour pressures are between 45 to 55 psi. Figure 11 illustrates peak hour pressures along the US -421 Corridor under the ML demand scenario. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -16- Technical Memorandum 4.0 �MCKIN4 &CREED Water Infrastructure Alternatives Analysis Hazen Figure 11: Alternative 2 Peak Hour Pressures for the ML Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -17- s `t 421 Corridor 2040 Most Likely Peak Hour Pressures w •era -- A.,��� uc.,» • ,.. 3 WrigMsh— ank 5 y. Legend � P51 ''0 S • -roaw • 0.0- • • fo.939y • 9 -soar • P.m • .e9a,� m,c a� utr� 9 - ,d• Sweeney wrP Figure 11: Alternative 2 Peak Hour Pressures for the ML Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -17- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn 421 Corridor 2040 A3i age za 1, Most Likely nFs Water Age Castle Rayne Tank i r �f ;~ Wrigfitsbore Tank s Narthchase Tank C Sweeney 4-- Legentl —2 -3aw . �. +ry, _ i � _ • _uw mane w.s �''4 Figure 12: Alternative 2 Water Ages for the ML Water Demand Scenario The Alternative 2b for the 1,500 gpm fire flow was used for the water age evaluation, as this configuration has the longest section of 16 "pipeline. Under the ML demand scenario, water age is estimated at approximately one day along the US -421 corridor as shown in Figure 12. The predicted TTHMs would average between 53 and 64 µg /L. It is expected that a few summer warm water samples may exceed the 80 µg/l, maximum contaminant level, but the majority of the samples at any compliance sample site would be well within the 80% of the MCL (64µg /L). However, at dead ends, the TTHMs would likely be closer to 70 ltg /L. 4.4.2.2. Alternative 2 - OP Demand Scenario Figure 13 illustrates the different peak hour pressures along the US -421 Corridor under the OP water demand scenario. At most locations along the US Hwy 421 Corridor, peak hour pressure range from 60 to 80 psi. In the Flemington area, the pressure drops to between 45 to 55 psi. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -18- v MCKIM&CREED Technical Memorandum 4.0 � Water Infrastructure Alternatives Analysis Hazen 421 Corridor 2040 Optimistic Peak Hour Pressure s �+ W�ights6oro Tank n t� Legend PSI C w•as9 ✓ �i •iO.A / 50.§59. ■ 5tl•89.. .eo9s� zow oPaml.ti. Sweeney V11TP ,.,, ax• -t9 2G• Figure 13: Alternative 2 Peak Hour Pressures for the OP Demand Scenario There is little difference in available fire flow observed between the demand scenarios in Alternative 2. Figure 14 illustrates the first pipeline configuration which achieves a 1,000 gpm minimum available fire flow. A small section of parallel 12 -inch is required to meet the 1,000 gpm at the Pender County line. Figure 15 illustrates the second pipeline configuration which provides a minimum fire flow of 1,500 gpm at the Pender County Line. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -19- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn 1. 421 Corridor 2040 Optimistic 1000 gpm AFF �3 - 4-p Fq i + Wrightsboro Tank Legend 4, AFF a N pal l.s+i+w,SGO gq^ � 500 eD+40m mG� �� .J +omo9omn+smawm 2mim apa. I.H. ' Sweeney ¢ ,. +a YJTP �. ar Figure 14: Alternative 2a Available Fire Flow with OP Water Demands US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -20- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn 421 Corridor 2040 OptiMiSft s 1500 gpm AFF /0007, .. -1 - - P � a S an.a+w ,+3 ll', 11 b. k - ,wn Figure 15: Alternative 2b Available Fire Flow for the OP Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -21- }. ... L"m AFF @YG p.1 4Aarrt�n S009L �'' a.�w a' 000 fmgom �j• 1990 aomio ls90 overt :a � rs9a aam+a a990 uart ... ✓ J 29 —tw, 250b ovrt . r � erase. lna:, xsa9 vnm - 20M OPMM. Sweeney t. o WTP �- — 1p•te• Nna»•, j J/� ///may /,, — 19 -3A' Figure 15: Alternative 2b Available Fire Flow for the OP Demand Scenario US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -21- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen Under the OP demand scenario, the increased water demand decreases water age to less than one day along the US Hwy 421 Corridor as shown in Figure 14. At the Pender County line, the water age on the US 421 Corridor is approximately 17 hours. The predicted TTHM concentration at the Pender County line would be approximately 49 µg /L, which is well below the recommended 64 µg /L (80% of the TTHM MCL). r P` r` r. Hy- ay+m O f .A 1':i tW' —sa Fe Wrighfsbaro Tank �Y �Y SW eenC]� • W� r 5 s �7 Figure 16: Alternative 2 Water Age with OP Water Demands. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -22- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.4.2.3. Alternative 2 Cost Opinion A preliminary cost opinion of Alternative 2a to provide both 1,000 gpm of available fire flow and Alternative 2b to provide 1,500 gpm of available fire flow are illustrated in Tables 2 and 3, respectively. The Phase 1 preliminary cost opinion for Alternative 2a, which includes a 16 -inch connection from the Sweeney WTP to the US Hwy 421 Corridor is $7.8 million to achieve a 1,000 - gpm fire flow goal and $8.1 million to meet a 1,500 -gp fire flow goal. Under the Optimistic demand scenario, a Phase 2 project would be required for both Alternative 2a and 2b. The Phase project consists of 3,700 -LF of 12 -inch main to parallel the 12 -inch installed in Phase 1. The preliminary cost opinion for Phase 2 is $0.5 million. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -23- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn Table 2: Cost Opinion for Alternative 2A- 1000 gpm Fire Flow PHASE 1 Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $160,000 $160,000 2 Erosion Control 1 LS $300,000 $300,000 3 Traffic Control 1 LS $9,500 $9,500 4 20" HDD Crossing NE Cape Fear River 2,500 LF $415 $1,037,500 5 16" C905, DR18, PVC Pipe 14,400 LF $92 $1,324,800 6 12" C900, DR18, PVC Pipe 16,580 LF $73 $1,210,340 7 20" Restrained Joint DIP, PC 250 20 LF $165 $3,300 8 16" Restrained Joint DIP, PC 250 1,900 LF $135 $256,500 9 12" Restrained Joint DIP, PC 350 100 LF $105 $10,500 9 DI Fittings 28,000 LBS $4.50 $148,500 10 30"y Bore & Jack -Road 400 LF $420 $168,000 11 30"y Bore & Jack - Railroad 200 LF $530 $106,000 12 24"y Bore & Jack - Railroad 100 LF $415 $41,500 12 16" Gate Valve 7 EA $6,600 $46,200 13 12" Gate Valve 6 EA $2,300 $13,800 14 Fire Hydrant w /GV & 6" DIP 31 EA $3,725 $115,475 15 Air Release Valve Assemblies w /MH 2 EA $5,500 $11,000 16 Flowable Fill (NCDOT Roads) 300 CY $110 $33,000 17 Remove & Replace Asphalt Pavement 2,750 LF $47 $129,250 18 Remove & Replace Concrete Pavement 210 SY $58 $12,180 19 Remove & Replace Driveways, Curb & Gutter, and Drainage Swale 1 LS $20,800 $20,800 20 Easement Acquisition 0.5 1 AC $30,000 $15,000 Subtotal $5,141,000 Technical Fees $848,300 Contingencies $1,796,800 Phase 1- Total Opinion of Probable Project Cost $7,786,100 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -24- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn PHASE 2 Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $10,000 $10,000 2 Erosion Control 1 LS $32,000 $32,000 3 Traffic Control 1 LS $1,200 $1,200 4 12" C900, DR18, PVC Pipe 3,700 LF $73 $270,100 5 DI Fittings 2,500 LBS $4.50 $11,250 6 12" Gate Valve 2 EA $2,300 $4,600 7 Remove & Replace Asphalt Pavement 2,00 LF $47 $9,400 Subtotal $339,000 Technical Fees $56,000 Contingencies $118,500 Phase 2 - Total Opinion of Probable Project Cost $513,500 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -25- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn Table 3: Cost estimate for Alternative 2B -1500 gpm fire flow Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $160,000 $160,000 2 Erosion Control 1 LS $300,000 $300,000 3 Traffic Control 1 LS $9,500 $9,500 4 20" HDD Crossing NE Cape Fear River 2,500 LF $415 $1,037,500 5 16" C905, DR18, PVC Pipe 24,200 LF $92 $2,226,400 6 12" C900, DR18, PVC Pipe 6,780 LF $73 $494,940 7 20" Restrained Joint DIP, PC 250 20 LF $165 $3,300 8 16" Restrained Joint DIP, PC 250 2,00 LF $135 $270,000 9 DI Fittings 33,000 LBS $4.50 $148,500 10 30 "y Bore & Jack -Road 400 LF $420 $168,000 11 30 "y Bore & Jack - Railroad 300 LF $530 $159,000 12 16" Gate Valve 10 EA $6,600 $66,000 13 12" Gate Valve 3 EA $2,300 $6,900 14 Fire Hydrant w /GV & 6" DIP 31 EA $3,725 $115,475 15 Air Release Valve Assemblies w /MH 2 EA $5,500 $11,000 16 Flowable Fill (NCDOT Roads) 300 CY $110 $33,000 17 Remove & Replace Asphalt Pavement 2,750 LF $47 $129,250 18 Remove & Replace Concrete Pavement 210 SY $58 $12,180 19 Remove & Replace Gravel Roads/Driveways 180 LY $10 $1,800 20 Remove & Replace Curb & Gutter 500 LY $20 $10,000 21 Remove & Replace Asphalt /Concrete Swales 150 LY $60 $9,000 22 Easement Acquisition 0.5 AC $30,000 $15,000 Subtotal $5,387,000 Technical Fees and Permitting $888,900 Contingencies $1,858,500 Total Opinion of Probable Project Cost $8,134,400 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -26- v McIQM &CREED Technical Memorandum 4.0 V Water Infrastructure Alternatives Analysis Hawn PHASE 2 Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $10,000 $10,000 2 Erosion Control 1 LS $32,000 $32,000 3 Traffic Control 1 LS $1,200 $1,200 4 12" C900, DR18, PVC Pipe 3,700 LF $73 $270,100 5 DI Fittings 2,500 LBS $4.50 $11,250 6 12" Gate Valve 2 EA $2,300 $4,600 7 Remove & Replace Asphalt Pavement 2,00 LF $47 $9,400 Subtotal $339,000 Technical Fees $56,000 Contingencies $118,500 Phase 2 - Total Opinion of Probable Project Cost $513,500 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -27- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.5 PREFERRED ALTERNATIVE To provide potable water service to the US Hwy 421 Corridor for future commercial and industrial development, several water system infrastructure alternatives were evaluated. The alternatives were developed to provide potable water service from the CFPUA via the Sweeney WTP. Table 4 summarizes the cost opinions for all the alternatives considered. Table 4: Summary of Cost Opinions Alternative Description Total Cost 12 -inch Connection to US Hwy 421 1 $10,346,300 from the Wrightsboro Tank 16 -inch Connection to US Hwy 421 2A —Phase 1 $7,786,100 from Sweeney WTP —1,000 gpm AFF 3,800 -LF of 12 -inch Parallel $513,500 2A — Phase 2 16 -inch Connection to US Hwy 421 213 — Phase 1 $8,134,000 from Sweeney WTP —1,500 gpm AFF 213 — Phase 2 3,800 -LF of 12 -inch Parallel $513,500 The cost opinion for the 12 -inch connection from the Wrightsboro Tank (Alternative 1) is approximately $10.35 million. The cost opinion for the 16 -inch connection from the Sweeney WTP (Alternative 2B) is approximately $8.1 million. Cost savings could be realized if a lower fire flow goal of 1,000 gpm was accepted. Given the County's desire to promote industrial development along the US Hwy 421 Corridor, Alternative 2B is recommended since it meets the fire flow goal of 1,500 gpm. Water age and predicted DBP formation for each alternative using the 2040 demands was discussed in Section 4.4. For the preferred alternative (Alternative 2), additional modeling was conducted to assess water age for the initial stages of development along US Hwy 421 when demands would be significantly less than the 2040 projections. Water age simulations determined that the water demand on the US Hwy 421 Corridor needs to exceed 150,000 gpd in order for water age to be approximately 48 hours and limit DBP formation. Based on the water demand projections in Technical Memorandum 2, the projected water demands for the ML and OP demand scenarios are 132,000 and 194,000 gpd in 2020. It can be expected that flushing of the US Hwy 421 pipelines may be required in the first 5 years until demands exceed 150,000 gpd. It is estimated that on a worse -case basis, CFPUA may need to flush US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -28- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 100,000 gpd until multiple customers are added to the system. The location of new customers is also important. It is recommended that the northern section of the proposed US Hwy 421 pipeline be isolated and remain out of service until new customers are added to the system. Isolation valves have been included in the cost opinions at approximately two for every linear mile of pipe. An alternative was examined to install a 12 -inch pipeline for water demands on one side of US 421 and a separate transmission main dedicated to fire protection on the other. The goal would be to lower water age and the potential for water quality concerns. However, this configuration was removed from further consideration due to cost. It was expected that the project cost would exceed $11 million for this configuration. 4.2 ANTICIPATED PERMIT REQUIREMENTS The anticipated permit requirements are presented in Table 5. It is expected that the permit requirements for the alternatives would be similar. Table 5: Anticipated Permit Requirements US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -29- Alternative Alternative Anticipated Permit Required Remarks 1 2 NCPWS Authorization to Construct Yes Yes Required for water system extensions NCDEQ Erosion & Sedimentation Land disturbance >1 acre requires Control Permit Yes Yes E &SC permit NCDEQ Storm Water Management Land disturbance >1 acre requires Permit (Exemption Anticipated) Yes Yes Storm Water Management permit NCDOT Standard Encroachment Required for installation of Yes Yes pipeline within the NCDOT right - Agreement of -way along US Hwy 421 NCDOT Controlled Access Required within the NCDOT Encroachment Agreement Yes Yes right -of -way at I -140 & US 421 interchange Required for impacts to Wetlands US Army Corps of Engineers and installations under Permitting Yes Yes waterways. Alt. 1 has potential impact to more acreage than Alt. 2 US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -29- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen 4.3 ANTICIPATED SCHEDULE The anticipated schedule for Alternative 2 is presented in Table 6. It is expected that the project will require 29 months to complete. The significant schedule drivers will be CAMA Major and US Army Corps of Engineers Permitting as well as route surveying and geotechnical engineering. Table 6: Anticipated Project Schedule for Alternative 2 Item Alternative 2 Design Required for installation of Division of Coastal Management 8 Months Bidding /Award 3 Months Complete Construction (Substantial) Yes Yes pipelines under navigable waters CAMA Major Permit in coastal counties Required for encroachment on CSX Railroad Lease or Permit Yes Yes CSX owned rail right -of -way 4.3 ANTICIPATED SCHEDULE The anticipated schedule for Alternative 2 is presented in Table 6. It is expected that the project will require 29 months to complete. The significant schedule drivers will be CAMA Major and US Army Corps of Engineers Permitting as well as route surveying and geotechnical engineering. Table 6: Anticipated Project Schedule for Alternative 2 Item Alternative 2 Design 6 Months Permit Review & Approval 8 Months Bidding /Award 3 Months Complete Construction (Substantial) 14 Months Total Estimated Project Timeline 31 Months 4.4 SUMMARY AND RECOMMENDATIONS To provide potable water service to the US Hwy 421 Corridor for future commercial and industrial development and fire protection, we recommend that the a new 16 -inch water transmission main be constructed from the existing CFPUA waster system near the southern end of the Corridor. Approximately 24,000 LF of main would be installed along US Hwy 421 and then transition to 12 -inch piping for the remaining 6,800 LF to the Pender County line. The cost opinion for Phase 1 of this alternative is approximately $8.1 million. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -30- Technical Memorandum 4.0 �McIIM &CREED Water Infrastructure Alternatives Analysis Hazen Water age along the US Hwy 421 Corridor is expected to be acceptable and should not represent DBP compliance concerns at projected water demands. However, water quality could be a concern during the initial stages until sufficient customers connect to the system representing a demand of approximately 150,000 gpd. Until that demand threshold is reached, flushing of the water transmission will be required to achieve sufficient turnover to limit DBP formation. It can be expected that flushing of the US Hwy 421 pipelines may be required in the first 5 years depending upon the water use and location of the initial customers. We recommend that northern sections of the proposed US Hwy 421 transmission main be isolated and remain out of service until new customers are added to the system. This project will require a water main crossing underneath the Northeast Cape Fear River via horizontal directional drilling. A CAMA Major Permit will be required for this crossing, which will include review by the US Army Corps of Engineers since this is considered navigable waters and is part of the Wilmington Harbor. Since these permitting steps can be time consuming and significant impacts on the project schedule, we recommend that scoping begin early in the project implementation. US Highway 421 Corridor Water and Sewer Utilities Preliminary Engineering Report -31- APPENDIX A DUKE ENERGY SUTTON PLANT COAL ASH LANDFILL LEACHATE CONVEYANCE SYSTEM EVALUATION TECHNICAL MEMORANDUM DUKE ENERGY SUTTON PLANT COAL ASH LANDFILL LEACHATE CONVEYANCE SYSTEM EVALUATION TECHNICAL MEMORANDUM January 2016 Prepared By: McKim & Creed, Inc. 243 N. Front Street Wilmington, NC 28401 Firm License F -1222 S�ttttisa�;Cdd° s SEAL� s F 25 �MFM4&CREED Section Page Section 1.0 Introduction ............................................... ..............................2 Section 2.0 Leachate Generation Rate .............................. ..............................2 Section 3.0 CFPUA Acceptance of Landfill Leachate .......... ..............................3 Section 4.0 Alternatives Criteria .................................... ..............................4 Section 5.0 Alternatives Analysis ................................... ..............................5 Section 6.0 Optional Design Considerations ...................... .............................12 Section 7.0 Anticipated Permits ..................................... .............................15 Section 8.0 Anticipated Schedules .................................. .............................16 Section 9.0 Summary and Recommendations .................... .............................18 Figures Figure 1 - US Highway 421 Corridor Figure 2 - Proposed Landfill and Leachate Management System Figure 3 - Alternative No. 1 Proposed System Figure 4 - Leachate Pump Station Potential Configurations Figure 5 - Alternative No. 2 Proposed System Appendices Appendix A - Alternative 1 Hydraulic Calculations Appendix B - Alternative 2 Hydraulic Calculations Appendix C - Hydraulic Calculations 4 -Inch and 6 -Inch Force Main Option Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 1.0 INTRODUCTION The Cape Fear Public Utility Authority ( CFPUA) and Duke Energy have entered into a contract to provide for the development of a Technical Memorandum (TM) to evaluate conveyance infrastructure necessary to accommodate leachate generated from proposed coal ash landfills near the Sutton Plant on US Highway 421. This evaluation will be performed concurrently with a Preliminary Engineering Report (PER) being prepared for CFPUA to provide for water and wastewater utilities along the US Highway 421 corridor. The overall focus of the TM will be to evaluate feasible alternatives to provide a pumping system and corresponding force main to convey leachate from the proposed landfill site to the existing CFPUA wastewater system. Analysis for each alternative includes hydraulic calculations, routing, opinions of project cost, schedule and permit requirements. Figure 1 provides an overview of the US Highway 421 corridor and the Sutton facility. 2.0 LEACHATE GENERATION RATE As per information provided by Duke Energy, the proposed coal ash landfill site will be located on Duke -owned property east of Sutton Lake in New Hanover County. The overall landfill is proposed with eleven (11) cells that may be constructed in three phases as follows: • Phase 1- Cells 3, 4, 5, 6, 7, 8 • Phase 2 - Cells 1, 2 • Phase 3 - Cells 9, 10, 11 Collection of leachate generated from the landfill will be accomplished via a leachate management system that will be located in the northwest corner of the landfill footprint. Based on preliminary information provided, the leachate management system will include two storage tanks with an approximate total storage capacity of 1,000,000 gallons and a truck load -out connection for pump & haul purposes. Figure 2 provides a schematic of the proposed landfill and location of the leachate management system. Leachate generation rates were provided by Duke Energy, and as indicated in Table 1, are anticipated to occur over a 12 -year period ranging from 50,000 GPD to 186,000 GPD. Pursuant to direction from Duke representatives, 186,000 GPD will be utilized for the evaluation of proposed conveyance infrastructure for this memorandum. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 2 Table 1— Leachate Life Cycle and Received Waste Summary Based on Peak Monthly Leachate Generation 200,009 180.009 160,000 140,999 m '� 120,000 .Q c �a !: iog9o9 n Y Si 8C,Cl7C 12 v 8 0019m 40,099 20,007 0 a t v a C i o L t a � ! f CC beo rg placed over entirefoot int rf: in preparation for finalclosure S a : f J :r r 0 l r r r r r r l l f r ! r r r l r r r 10,000,000 9, aOO 8,000,000 7. ODD, DOG 6.000.000 n O 8 5.006,000 m 9 e 4,000.079 3.000, 070 2,O0a 009 1,ODO,COO D 0 2 4 6 8 10 12 Elapsed Time (Years; 3.0 CFPUA ACCEPTANCE OF LANDFILL LEACHATE It is our understanding that Duke Energy is consulting directly with CFPUA to determine constituents associated with the leachate and for acceptance of the leachate for discharge to the Northside Wastewater Treatment Plant. For the purposes of this memorandum, it is assumed that the leachate will be accepted by the CFPUA, and /or Duke Energy will provide pre - treatment as required for discharge to the Northside facility. Therefore, the evaluations and recommendations presented herein are based solely on hydraulic requirements to convey the leachate to the Northside facility and do not include treatment (or pre - treatment) recommendations. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 3 4.0 ALTERNATIVES CRITERIA Primarily, the alternatives considered in this memorandum are focused on a pump station and dedicated force main configuration that would collect the landfill leachate and convey it to the CFPUA public utility system. The pump station and force main sizing were evaluated based on the previously noted 186,000 GPD (peak daily flow average) of landfill leachate. Pursuant to NC Department of Environmental Quality (DEQ) design requirements, a peak hourly factor of 2.5 was applied to the average daily flow to determine a minimum pumping rate to convey the leachate. In addition to the DEQ regulatory requirement, the peaking factor provides a'factor of safety' and flexibility to accommodate instantaneous or peak flows higher than anticipated in the current landfill design. Summarily, Table 2 provides the pumping capacity minimum design criteria established for the alternatives analysis: Table 2 - Pumping Capacity Minimum Design Criteria Average Daily Flow Average Daily Flow Peak Hourly Factor Minimum Peak Pump Rate (GPM) 186,000 GPD 129 GPM 2.5 323 GPM For the purposes of this memorandum, 325 GPM has been used as the minimum design peak pumping rate. Additional criteria dictated by DEQ establish a minimum threshold of 2 feet per second (FPS) velocity in the proposed force main, with typical design ranges for force mains between 2 FPS and 5 FPS. The minimum 2 FPS velocity provides scouring of the force main and resuspension of solids that may settle during periods when the pumps are not operating, while the upper threshold of 5 FPS minimizes thrust forces in the pipeline and optimizes motor HP sizing for associated pumping facilities. Table 3 details velocities for commercially available utility pipelines associated with the minimum peak pump rate identified in Table 2. Table 3 - Minimum Force Main Sizing Pipe Diameter Recommended Design Peak Pump Rate Velocity at Design Peak Pump Rate 4" 325 GPM 8.3 FPS 6" 325 GPM 3.7 FPS 8" 325 GPM 2.1 FPS Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 4 Review of Table 3 indicates that a 4 -inch force main would create velocities well above the typical 2 FPS to 5 FPS range recommended for force mains and was deemed not feasible. Table 2 also indicates that either 6 -inch or 8 -inch diameter pipeline would be acceptable to achieve required and /or desired velocities; therefore, alternatives were evaluated for feasibility based upon either a 6 -inch or 8 -inch force main to convey leachate generated at the proposed Duke Energy landfill to the CFPUA system. 5.0 ALTERNATIVES ANALYSIS Examination of the geographic location of the proposed landfill and the existing CFPUA wastewater system yielded two, feasible primary alternatives for evaluation: • Alternative 1 - Discharge to CFPUA Chair Road Pump Station • Alternative 2 - Discharge to CFPUA PS 12 Each alternative was based upon the construction of a pump station or pumping facility that would be located at the site of the proposed landfill leachate management system. The primary delineation between the alternatives was the potential route of the conveyance force main and ultimate discharge point to the CFPUA system. An analysis of each alternative is detailed as follows: Alternative 1- Discharge to CFPUA Chair Road Pump Station Alternative 1 entails construction of a pumping facility located at the proposed landfill leachate management system site. Leachate generated would be collected in two (2) proposed 500,000 gallon storage tanks and the proposed pumping facility would convey leachate from the tanks through a force main to the CFPUA system. For this alternative, the force main would be routed from the leachate management site to US Highway 421, and then south along the US Highway 421 right -of -way to the intersection of an existing Duke -owned transmission easement. The proposed force main would follow the transmission easement northeasterly and then cross under the NE Cape Fear River, where it would ultimately discharge to the CFPUA's Chair Road pump station. Refer to Figure 3 for the proposed Alternative 1 route. Hydraulic modeling and review of the proposed route for Alternative 1 yielded the following specifics: • One duplex pumping facility with 15 HP pumps. • 31,000 linear feet total of force main. 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 5 • A 150 LF railroad crossing under is required within the right -of -way of US Highway 421. Tax records indicate that the railway in this area is privately owned, however, it is anticipated that NCDOT will govern the permitting of the crossing as it is a public right -of- way • A capacity charge of $4.75 /gallon to Duke Energy will be applicable to the Chair Road PS option. This results in an additional cost of $883,500 for the 186,000 GPD capacity. • 4,000 LF of horizontal directional drill under the NE Cape Fear River. • Acquisition of an easement would be required from Southern Equipment Company or Jenkins Gas & Oil Company for installation of the force main from Duke property to the US Highway 421 right -of -way. A 20 -foot wide permanent utility easement in conjunction with a 10 -foot wide temporary construction easement is recommended. • Hydraulic calculations on the proposed route were developed based on a 6 -inch and 8 -inch force main. For the purposes of this evaluation, pipe materials have been based on PVC which is the CFPUA standard for utility force mains, is inert to gasses, and provides reduced frictional characteristics when compared to ductile iron or other ferrous material pipe. Table 4 provides a summary of results associated with the force main and pump facility sizing for the required leachate volume. Table 4 - Hydraulic Results Alternative 1 Refer to Ap gendix A - Alternative 1 Hydraulic Calculations Based on the hydraulic calculations, a 6 -inch force main will produce pipe pressures in the range of 160 psi during normal operating ranges and potential surge pressures of approximately 216 psi. The standard pipeline pressure class for public utility force mains is PVC C -900 Class 235 psi, with a maximum recommended operating range of approximately 150 psi. Subsequently, utilizing a 6- inch force main would approach maximum recommended operating ranges as well as maximum pressure rating under surge conditions. In order to effectively utilize the 6 -inch force main, significant surge relief systems would be required at the pumping facility, and possibly along the pipeline route, to accommodate surge pressures. Additionally, a higher pressure class force main would be required, which would likely necessitate the use of ductile iron pipe in order to obtain a pressure rating sufficient to accommodate the operation pressures noted. An additional constraint of the 6 -inch diameter is the lack of flexibility available should Duke require capacity beyond 186,000 GPD. Increased flow at this diameter would significantly increase pressure and pumping requirements and would limit the ability to accommodate higher leachate discharge capacities. Sutton Plant - Coal Ash Landfill Leachate Conveyance System Evaluation 6 Recommended Estimated Pipe Velocity at Design Force Main Required Design Peak Pump Surge Diameter Peak Pump Rate Pressure Motor HP Rate Pressure 6" 325 GPM 3.7 FPS 160 psi 224 psi 50 HP 8" 325 GPM 2.1 FPS 51 psi 87 psi 15 HP Based on the hydraulic calculations, a 6 -inch force main will produce pipe pressures in the range of 160 psi during normal operating ranges and potential surge pressures of approximately 216 psi. The standard pipeline pressure class for public utility force mains is PVC C -900 Class 235 psi, with a maximum recommended operating range of approximately 150 psi. Subsequently, utilizing a 6- inch force main would approach maximum recommended operating ranges as well as maximum pressure rating under surge conditions. In order to effectively utilize the 6 -inch force main, significant surge relief systems would be required at the pumping facility, and possibly along the pipeline route, to accommodate surge pressures. Additionally, a higher pressure class force main would be required, which would likely necessitate the use of ductile iron pipe in order to obtain a pressure rating sufficient to accommodate the operation pressures noted. An additional constraint of the 6 -inch diameter is the lack of flexibility available should Duke require capacity beyond 186,000 GPD. Increased flow at this diameter would significantly increase pressure and pumping requirements and would limit the ability to accommodate higher leachate discharge capacities. Sutton Plant - Coal Ash Landfill Leachate Conveyance System Evaluation 6 Although driven by current market conditions, ductile iron is typically more costly than PVC, and while cost savings would be realized with a 6 -inch versus an 8 -inch force main, it would be offset by the higher cost of ductile iron pipe. Based on these constraints, the 6 -inch force main was determined to be not feasible. Therefore, it is recommended that an 8 -inch force main be constructed for this alternative as it provides the most advantageous hydraulic conditions and meets the minimum required capacity needs for the leachate volumes. Leachate Pumping Facift As previously noted, the leachate pumping facility would be located at the proposed leachate management system in the northwest area of the landfill site. Per Duke representatives, two (2) storage tanks with a total capacity of approximately 1,000,000 gallons will be constructed at this site; however, design details are still pending on the height and size of the tankage. For the purposes of this memorandum, the proposed leachate pumping facility has been based on a typical, below -grade wetwell with duplex submersible pumps. A primary advantage of the below - grade wetwell configuration is that leachate collected in the landfill can be conveyed via gravity directly to the wetwell and bypass the leachate tanks if desired. If the proposed tankage is above grade and has sufficient storage, the wetwell configuration can be eliminated and a more economical above grade pumping system can be implemented. However, this pumping configuration would likely require the leachate tankage to be in operation at all times to provide sufficient suction pressure to the pumps. Significant costs can be attributable to construction of the below grade wetwell, therefore, opinions of cost have been provided for each pump scenario. As shown in Table 4,15 HP motors would be required for the proposed pumping station. It is noted that growth in the US 421 corridor may impact hydraulic conditions that could necessitate upgrades to the pumps (i.e., motor upsize or impeller change), however, these are anticipated to minimal and can be readily incorporated with the proposed configuration. Figure 4 provides a schematic of the potential pumping configurations and Table 5 provides an opinion of probable project cost for Alternative 1. Appendix A provides hydraulic calculations for Alternative 1. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation Table 5 - Alternative 1 Opinion of Probable Project Cost Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $125,000 LS $125,000 2 8" Force Main C900 PVC 22,000 LF $81 LF $1,787,500 3 8" Force Main DIP 3,000 LF $106 LF $318,750 4 Bore and Jack 16" Diameter Steel Encasement 500 LF $313 LF $156,250 5 8" DI Carrier Pipe 500 LF $119 LF $59,375 6 Directional Drill HDPE Class 200 SDR9 5,500 LF $469 LF $2,578,125 7 Air Release Valve in Manhole 5 EA $6,250 EA $31,250 8 8" Gate Valves 8 EA $1,250 EA $10,000 9 DI Restrained Fittings 10,000 LBS $7 LBS $70,000 10 Wastewater Pump Station 1 LS $750,000 LS $750,000 11 Remove and Replace Curb and Gutter 200 LF $38 LF $7,500 12 Remove and Replace Gravel Drives 500 SY $13 SY $6,250 13 Remove and Replace Asphalt Drives 500 SY $50 SY $25,000 14 Remove and Replace Concrete Drive 500 LF $100 LF $50,000 15 Silt Fence 7,000 LF $4 LF $26,250 16 Undercut Excavation w /Select Material 4,500 CY $19 CY $84,375 17 Stabilization Stone (6" Depth) 5,000 LF $4 LF $18,750 Subtotal $6,104,375 Technical Fees $732,525 Capacity Charge ($4.75 /Gallon) $883,500 Total Opinion of Probable Project Cost $7,720,400 If an above ground pump station can be constructed and the wetwell configuration eliminated, a savings of approximately $400,000 could be realized and the total opinion of probable project cost could be reduced to approximately $7.3M for Alternative 1. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 8 Alternative 2 - Discharge to CFPUA PS 12 Identical in concept to Alternative 1, Alternative 2 requires construction of a pumping facility located at the proposed landfill leachate management system site and leachate collected would be conveyed through a force main to the CFPUA system. For this alternative, the force main would be routed from the leachate management site to US Highway 421, and then south along the US Highway 421 right -of -way to existing dual 8 -inch CFPUA force mains south of the Isabelle Holmes Bridge. The proposed force main would connect to the dual force mains, which would convey the leachate beneath the NE Cape Fear River to the CFPUA's PS 12. On the east side of the river, the dual force mains would require a short extension to connect to PS 12 as well as a valved, bypass connection to the PS 12 discharge force main. This connection provides the ability to bypass PS 12 and convey leachate flow directly through the PS 12 force main. This connection provides operational flexibility for both incident management and maintenance that may require PS 12 to be removed from service. Refer to Figure 5 for proposed Alternative 2 route. Hydraulic modeling and review of the proposed route for Alternative 2 yielded the following: • One duplex pumping facility with 20 HP pumps. • 37,000 linear feet total of force main. • 150 LF railroad crossing under a CSX owned railroad via bore & jack encasement is required for the force main. A permit or lease agreement will be required with CSX railroad for this installation. • 300 LF railroad crossing is required within the right -of -way of US Highway 421 in two locations. Tax records indicate that the railway in these areas is privately owned, however, it is anticipated that NCDOT will govern the permitting of the crossing as it is within public right -of -way. • 700 LF of trenchless (directional drill or bore & jack encasement) crossing under I -140 at US Highway 421, which is a controlled access right -of -way. Therefore, an NCDOT Controlled Access Encroachment Agreement will be required for this crossing. • Acquisition of an easement would be required from Southern Equipment Company or Jenkins Gas & Oil Company for installation of the force main from Duke property to the US Highway 421 right -of -way. A 20 -foot wide permanent utility easement in conjunction with a 10 -foot wide temporary construction easement is recommended. Similar to Alternative 1, hydraulic calculations on the proposed route were developed based on a 6 -inch and 8 -inch force main utilizing PVC pipe. Table 6 provides a summary of results associated with the force main and pump facility sizing. Sutton Plant - Coal Ash Landfill Leachate Conveyance System Evaluation 9 Table 6 — Hydraulic Results Alternative 2 Refer to Appendix B — Alternative 2 Hydraulic Calculations Similar to Alternative 1, the 6 -inch force main option creates hydraulic conditions that exceed typical recommended working pressures and maximum surge pressures for utility pipelines. Therefore, the 8 -inch force main is the recommended diameter for Alternative 2. Leachate Pumping Facility The leachate pumping facility would essentially be identical to Alternative 1, although as can be seen in Table 6, the motor HP would increase slightly from 15 HP to 20 HP. This is due primarily to frictional losses in the additional length of force main associated with the Alternative 2 route. Similar to Alternative 1, growth in the US 421 corridor may impact hydraulic conditions that could necessitate upgrades to the pumps, however, these are anticipated to be minimal and can be readily incorporated with the proposed configuration. Alternative 2 would have the same potential cost savings available should an above ground pumping facility be constructed in lieu of a below -grade wetwell configuration. It is noted that Alternative 2 does require additional length in comparison to Alternative 1, however, it offers several distinct advantages: • Alternative 1 requires approximately 4,000 linear feet of force main to be horizontally directionally drilled beneath the NE Cape Fear River. This is substantial construction cost due to the length of the drill and the location in an area that is predominantly wetlands. • The Alternative 1 NE Cape Fear River crossing will require significant environmental permitting and could severely impact overall project timeline. • Alternative 2 utilizes existing CFPUA owned force mains that are in -place under the Cape Fear River and available for conveyance of wastewater. • Alternative 2 does not require a capacity charge as is noted in Alternative 1. Figure 4 provides a schematic of the potential pumping configurations and Table 7 (following page) provides an opinion of probable project cost for Alternative 2. Appendix B provides hydraulic calculations for Alternative 2. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 10 Recommended Estimated Pipe Velocity at Design Force Main Required Design Peak Pump Surge Diameter Peak Pump Rate Pressure Motor HP Rate Pressure 6" 325 GPM 3.7 FPS 182 psi 256 psi 60 HP 8" 325 GPM 2.1 FPS 60 psi 93 psi 20 HP Similar to Alternative 1, the 6 -inch force main option creates hydraulic conditions that exceed typical recommended working pressures and maximum surge pressures for utility pipelines. Therefore, the 8 -inch force main is the recommended diameter for Alternative 2. Leachate Pumping Facility The leachate pumping facility would essentially be identical to Alternative 1, although as can be seen in Table 6, the motor HP would increase slightly from 15 HP to 20 HP. This is due primarily to frictional losses in the additional length of force main associated with the Alternative 2 route. Similar to Alternative 1, growth in the US 421 corridor may impact hydraulic conditions that could necessitate upgrades to the pumps, however, these are anticipated to be minimal and can be readily incorporated with the proposed configuration. Alternative 2 would have the same potential cost savings available should an above ground pumping facility be constructed in lieu of a below -grade wetwell configuration. It is noted that Alternative 2 does require additional length in comparison to Alternative 1, however, it offers several distinct advantages: • Alternative 1 requires approximately 4,000 linear feet of force main to be horizontally directionally drilled beneath the NE Cape Fear River. This is substantial construction cost due to the length of the drill and the location in an area that is predominantly wetlands. • The Alternative 1 NE Cape Fear River crossing will require significant environmental permitting and could severely impact overall project timeline. • Alternative 2 utilizes existing CFPUA owned force mains that are in -place under the Cape Fear River and available for conveyance of wastewater. • Alternative 2 does not require a capacity charge as is noted in Alternative 1. Figure 4 provides a schematic of the potential pumping configurations and Table 7 (following page) provides an opinion of probable project cost for Alternative 2. Appendix B provides hydraulic calculations for Alternative 2. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 10 Table 7 - Alternative 2 Opinion of Probable Project Cost Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $125,000 LS $125,000 2 8" Force Main C900 PVC 31,000 LF $81 LF $2,518,750 3 8" Force Main DIP 3,000 LF $106 LF $318,750 4 Bore and Jack 16" Diameter Steel Encasement 1,500 LF $313 LF $468,750 5 8" DI Carrier Pipe 1,500 LF $119 LF $178,125 6 Directional Drill HDPE Class 200 SDR9 1,500 LF $469 LF $703,125 7 Air Release Valve in Manhole 6 EA $6,250 EA $37,500 8 8" Gate Valves 8 EA $1,250 EA $10,000 9 DI Restrained Fittings 12,000 LBS $7 LBS $84,000 10 Wastewater Pump Station 1 LS $750,000 LS $750,000 11 Remove and Replace Curb and Gutter 200 LF $38 LF $7,500 12 Remove and Replace Gravel Drives 500 SY $13 SY $6,250 13 Remove and Replace Asphalt Drives 500 SY $50 SY $25,000 14 Remove and Replace Concrete Drive 500 LF $100 LF $50,000 15 Silt Fence 7,000 LF $4 LF $26,250 16 Undercut Excavation w /Select Material 3,500 CY $19 CY $65,625 17 Stabilization Stone (6" Depth) 3,000 LF $4 LF $11,250 Subtotal $5,385,875 Technical Fees $646,305 Total Opinion of Probable Project Cost $6,032,180 Similar to Alternative 1, construction of an above ground pumping facility would reduce the cost of Alternative 2 by approximately $400,000 for an approximate total opinion of probable project cost of $5.6M. Sutton Plant - Coal Ash Landfill Leachate Conveyance System Evaluation 11 6.0 OPTIONAL DESIGN CONSIDERATIONS The alternatives analysis presented in Section 5.0 of this TM have been based on NCDEQ Minimum Design Criteria (MDC). A primary component of the MDC includes the minimum peak hourly factor (PHF) of 2.5 which is applied to average daily flows for all wastewater pump station facilities. Subsequently, application of the PHF results in significantly increased pumping capacities and force main diameters when compared to the sizing that would be required to only convey the average daily flow. As an optional design consideration, it may be feasible to utilize the proposed two (2) each 500,000 gallon leachate storage tanks to buffer the peak hourly flows and provide a pump station and force main system sized to accommodate the projected average daily flow. Based on the daily flow of 186,000 GPD, the leachate storage tanks equate to a peaking capability of approximately 5.4 (i.e., 1,000,000 MG storage / 186,000 GPD = 5.37), which far exceeds the NCDEQ minimum of 2.5. Therefore, it is feasible for Duke Energy to potentially obtain an NCDEQ permit that incorporates the storage tanks to buffer the peak hourly flows required by the MDC. It is noted that this would likely be viewed as a variance from the regulatory requirements and would require submittal of the standard NCDEQ Application for Force Mains and Pump Stations in lieu of the NCDEQ Fast Track Application that would normally apply. As noted in Section 5.0 Alternative 2, the required force main diameter is 8 -inch and the pumping facility would include duplex pumps sized at 20 HP. The following Table 7A represents the hydraulic results and available capacities for 4 -inch and 6 -inch diameter pipe based on the maximum flow available with and without the MDC peak hourly factor. Table 7A — Capacities of Commercially Available Pipe Diameters Refer to Appendix C for 4 -inch and 6 -inch Hydraulic Calculations Pipe Capacity With Capacity with Minimum Required Pumping Rate Diameter No PHF 2.5 PHF Pipe Velocity Motor HP 4" 80 GPM 115,200 GPD 46,080 GPD 2.0 FPS 15 -20 HP 6" 180 GPM 259,200 GPD 103,680 GPD 2.0 FPS 10 -15 HP As shown in Table 7A, the 4 -inch diameter pipe would not be capable of meeting the 186,000 GPD flow in any condition, however, the 6 -inch diameter pipe would exceed this capacity without the PHF applied. Subsequently, neither pipe diameter would be capable of meeting the 186,000 GPD if the 2.5 peak hourly factor is applied. An opinion of probable project costs for the 4 -inch and 6 -inch diameter force main options are provided in Table 7B and Table 7C respectively: Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 12 Table 7B — 4 -Inch Force Main Option Opinion of Probable Project Cost Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $125,000 LS $125,000 2 4" Force Main C900 PVC 31,000 LF $65 LF $2,015,000 3 4" Force Main DIP 3,000 LF $85 LF $255,000 4 Bore and Jack 16" Diameter Steel Encasement 1,500 LF $275 LF $412,500 5 4" DI Carrier Pipe 1,500 LF $100 LF $150,000 6 Directional Drill HDPE Class 200 SDR9 1,500 LF $400 LF $600,000 7 Air Release Valve in Manhole 6 EA $6,250 EA $37,500 8 4" Gate Valves 8 EA $800 EA $6,400 9 DI Restrained Fittings 8,000 LBS $7 LBS $56,000 10 Wastewater Pump Station 1 LS $750,000 LS $750,000 11 Remove and Replace Curb and Gutter 200 LF $38 LF $7,500 12 Remove and Replace Gravel Drives 500 SY $13 SY $6,250 13 Remove and Replace Asphalt Drives 500 SY $50 SY $25,000 14 Remove and Replace Concrete Drive 500 LF $100 LF $50,000 15 Silt Fence 7,000 LF $4 LF $26,250 16 Undercut Excavation w /Select Material 3,500 CY $19 CY $65,625 17 Stabilization Stone (6" Depth) 3,000 LF $4 LF $11,250 Subtotal $4,599,275 Technical Fees $551,913 Total Opinion of Probable Project Cost $5,151,188 Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 13 Table 7C - 6 -Inch Force Main Option Opinion of Probable Project Cost Item Description Quantity Unit Price Total Cost 1 Mobilization, Bonds, Insurance 1 LS $125,000 LS $125,000 2 6" Force Main C900 PVC 31,000 LF $75 LF $2,325,000 3 6" Force Main DIP 3,000 LF $95 LF $285,000 4 Bore and Jack 16" Diameter Steel Encasement 1,500 LF $313 LF $468,750 5 6" DI Carrier Pipe 1,500 LF $110 LF $165,000 6 Directional Drill HDPE Class 200 SDR9 1,500 LF $430 LF $645,000 7 Air Release Valve in Manhole 6 EA $6,250 EA $37,500 8 6" Gate Valves 8 EA $900 EA $7,200 9 DI Restrained Fittings 10,000 LBS $7 LBS $70,000 10 Wastewater Pump Station 1 LS $750,000 LS $750,000 11 Remove and Replace Curb and Gutter 200 LF $38 LF $7,500 12 Remove and Replace Gravel Drives 500 SY $13 SY $6,250 13 Remove and Replace Asphalt Drives 500 SY $50 SY $25,000 14 Remove and Replace Concrete Drive 500 LF $100 LF $50,000 15 Silt Fence 7,000 LF $4 LF $26,250 16 Undercut Excavation w /Select Material 3,500 CY $19 CY $65,625 17 Stabilization Stone (6" Depth) 3,000 LF $4 LF $11,250 Subtotal $5,070,325 Technical Fees $608,439 Total Opinion of Probable Project Cost $5,678,764 Comparison of the recommended Alternative 2 in Section 5.0 of this memorandum and the opinion of probable costs for the 4 -inch and 6 -inch force main options is provided in Table 7D: Table 7D - Comparison of Opinions of Probable Project Cost Option Opinion of Probable Project Cost 4 -Inch Force Main Option $5.2M 6 -Inch Force Main Option $5.7M 8 -Inch Force Main (Recommended Alternative 2) $6.OM Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 14 As indicated in Table 7D, a reduction in total project cost ranging from $03M to $0.8M could be realized by constructing either a 4 -inch or 6 -inch force main in lieu of the 8 -inch force main recommended in Section 5.0 of this report. The viability of these alternative sizes to accommodate the leachate system would need to be determined by Duke Energy with respect to capacities required and desired permit approach. 7.0 ANTICIPATED PERMITS Anticipated permits for Alternative 1 and Alternative 2 are detailed in Table 8 below: Table 8 — Anticipated Permit Requirements Anticipated Permit Required Alternative 1 Alternative 2 Remarks NCDEQ Fast Track Permit for Required for the pump station and force Pump Stations & Force Mains Yes Yes main NCDEQ Erosion & Sedimentation Land disturbance >1 acre requires E &SC Control Permit Yes Yes permit NCDEQ Storm Water Management Land disturbance >1 acre requires Storm Permit (Exemption Anticipated) Yes Yes Water Management permit NCDOT Standard Encroachment Required for installation of pipeline Agreement Yes Yes within the NCDOT right of way of US 421 Required for installation of pipeline NCDOT Controlled Access No Yes within the NCDOT right of way at I -140 Encroachment Agreement & US 421 interchange Required for impacts to Wetlands and US Army Corps of Engineers installations under waterways. Yes Yes Alternative 1 will require additional Permitting permitting for the NE Cape Fear river crossing as compared to Alternative 2. Division of Coastal Management Required for installation of pipelines Yes Yes under navigable waters in coastal CAMA Major Permit counties NC Department of Administration Required for installation beneath the NE Approval Yes No Cape Fear River CSX Railroad Lease or Permit Yes Yes Required for any crossing or parallelism of a CSX owned rail right of way Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 15 As indicated in Table 8, the primary differences between alternatives are that Alternative 1 will require additional permitting for crossing the NE Cape Fear River and Alternative 2 will require an NCDOT Controlled Access Encroachment Agreement for crossing I -140. 8.0 ANTICIPATED SCHEDULES Review of the alternatives indicates that each will have similar schedule drivers to include design, permit, and construction; however, the primary delineator for each alternative schedule is related to the permits identified in Table 8 of this memorandum. Specifically, Alternative 1 is anticipated to have an increased overall completion timeline due to the required crossing of the NE Cape Fear River. Permits required by the NCDEQ US Army Corps of Engineers, and the NC Department of Administration can have significant timelines required for approval and can impact the ability to expedite overall completion of the project. For comparison purposes, anticipated schedules for each alternative are provided as follows. Note that the schedules provided are based on a traditional Design/Bid/Build method: Table 9 — Anticipated Project Schedule Item Alternative 1 Alternative 2 Design 3 -4 Months 3 -4 Months Permit Review & Approval 7 -8 Months 4 -5 Months Advertise for Bids 1 Month 1 Month Open Bids /Start Construction 1 Month 1 Month Complete Construction (Substantial) 9 Months 8 Months Total Estimated Project Timeline 22 -23 Months 18 -19 Months Based on discussions with Duke, it is understood that time is of the essence as the proposed landfill is schedule to be completed in December 2016. Given this timeline, there are strategies available to lessen the overall project timeline. The following represents an accelerated timeline for Alternative 2, which is the recommended Alternative. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 16 Table 10 - Accelerated Project Schedule Approach - Recommended Alternative 2 Summarily, concurrent advertisement for bids and submittal for permits will provide an opportunity for an expedited schedule. Strategies that could be considered include: • Design -Build Delivery Method - a design -build approach may potentially shorten the schedule by allowing the contractor and engineer to work together for project completion, however, it is not anticipated to provide a significant timeline reduction over that which has been provided in Table 10, as permit timelines will dictate the project critical path. • Utilize Multiple Contractors - the construction project can be broken down into two separate contracts that will allow multiple contractors to work concurrently to complete the project. Given that the majority of the work involves pipeline construction this would be a readily available means of reducing overall project timeline. • Pre - Purchase Materials - shop drawing submittal, review, approval and ultimate delivery of materials can be a major factor in a project schedule. Duke could pre - purchase materials such as pipe, pumps, fittings, etc. and provide these to the contractor for construction. • Design & Permit Approach - it is anticipated that several permits such as NCDOT Encroachments for I -140 and CSX Railroad approvals may require extended times for review and approval. It is recommended that the design approach focus on the specific crossings associated with such permits. These can be prepared and submitted in the initial stages of design while the remaining design and permit efforts are underway. It is strongly recommended that Duke consider this item as it may be necessary to achieve the accelerated timeline noted in Table 10. It is noted that schedules provided are estimated and varying review times of regulatory agencies could impact the schedules as presented. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 17 Alternative 2 Item Cumulative Timeline Complete Design and Submit for Permits & Concurrently 3 Months Advertise for Bids Upon Completion of Design Permit Approval (bids in hand prior to, or concurrent with, 3 -4 Months permit approval, accelerated permits for RR & I -140) Construction Duration (multiple contracts, pre - purchase of 6 -8 Months m materials) Total Potential Accelerated Project Timeline 12 -15 Months Summarily, concurrent advertisement for bids and submittal for permits will provide an opportunity for an expedited schedule. Strategies that could be considered include: • Design -Build Delivery Method - a design -build approach may potentially shorten the schedule by allowing the contractor and engineer to work together for project completion, however, it is not anticipated to provide a significant timeline reduction over that which has been provided in Table 10, as permit timelines will dictate the project critical path. • Utilize Multiple Contractors - the construction project can be broken down into two separate contracts that will allow multiple contractors to work concurrently to complete the project. Given that the majority of the work involves pipeline construction this would be a readily available means of reducing overall project timeline. • Pre - Purchase Materials - shop drawing submittal, review, approval and ultimate delivery of materials can be a major factor in a project schedule. Duke could pre - purchase materials such as pipe, pumps, fittings, etc. and provide these to the contractor for construction. • Design & Permit Approach - it is anticipated that several permits such as NCDOT Encroachments for I -140 and CSX Railroad approvals may require extended times for review and approval. It is recommended that the design approach focus on the specific crossings associated with such permits. These can be prepared and submitted in the initial stages of design while the remaining design and permit efforts are underway. It is strongly recommended that Duke consider this item as it may be necessary to achieve the accelerated timeline noted in Table 10. It is noted that schedules provided are estimated and varying review times of regulatory agencies could impact the schedules as presented. Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 17 9.0 SUMMARY AND RECOMMENDATIONS Duke Energy desires a solution to collect leachate at their proposed coal ash landfill site for the Sutton Facility located on US Highway 421 in New Hanover County and convey the leachate to the CFPUA utility system for treatment. An evaluation of feasible alternatives was conducted, which included two primary alternatives: Alternative 1- This alternative entails construction of a pumping facility located at the proposed landfill leachate management system site. Leachate generated would be collected in two (2) proposed 500,000 gallon storage tanks (1,000,000 gallons storage total) and the proposed pumping facility would convey leachate from the tanks through a force main to the CFPUA system. Leachate would be conveyed to the CFPUA's Chair Road Pump Station located on the east side of the NE Cape Fear River north of the City of Wilmington. Treatment for the leachate would be accommodated by the Northside WWTP. Refer to Figure 3 for the proposed Alternative 1 route. Alternative 2 (Recommended) - Similar to Alternative 1, Alternative 2 requires construction of a pumping facility located at the proposed landfill leachate management system site and leachate collected would be conveyed through a force main to the CFPUA system. For this alternative, leachate would be conveyed, and connected to, existing dual force mains owned by CFPUA, which would convey the leachate beneath the NE Cape Fear River to the CFPUA's PS 12. Ultimately, treatment would be accomplished by the Northside WWTP. Refer to Figure 5 for the proposed Alternative 2 route. 4 -Inch or 6 -Inch Force Main Option - As detailed in Section 6.0, it may be feasible to construct a smaller diameter pipeline to serve the leachate landfill for the recommended Alternative 2 system. Implementation of either a 4 -inch or 6 -inch diameter force main would reduce total project costs, but would also result in a reduction of available conveyance capacity when compared to the fl- inch force main recommended in Alternative 2 above. With this option, Duke Energy could choose to operate at a lower system capacity and maintain the 2.5 PHF required by NCDEQ Minimum Design Criteria, or submit a permit application on the premise of utilizing the proposed leachate storage tanks to mitigate peak flows. Project costs could be reduced by $03M for the 6- inch force main option and by $0.8M for the 4 -inch force main option. While each of these alternatives is likely feasible, it is noted that the permit process required to mitigate peak flows with the leachate tankage could potentially add an additional 30 -60 days to the schedule provided in Section 8.0. A comparison of alternatives evaluated is provided in Table 11 as follows: Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 18 Table 11— Alternatives Matrix Item Alternative 1 Alternative 2 Best Alternative Opinion of Probable Project Cost $73M to $7.7M* $5.6M to $6.OM* 2 Pump Station Required Yes Yes N/A Force Main Length 31,000 37,000 1 Force Main Size 8 -inch 8 -inch N/A Pump Station HP Required 15 20 N/A Ease of Permitting N Y 2 Overall Schedule N Y 2 *The lowest cost in the provided range assumes construction of an above - ground pumping facility in lieu of a traditional wetwell arrangement. Based on the results presented in this report and the original scope of work for this memorandum, Alternative 2 meets the identified objectives of Duke Energy to collect and convey leachate from the proposed coal ash landfill site to the CFPUA wastewater system. Specifically, Alternative 2 is comprised of the following: • 37,000 LF of 8 -Inch PVC C -900 Force Main • Duplex 20 HP Leachate Pump Station • Connection to existing CFPUA dual 8 -inch diameter force mains under the NE Cape Fear River • Conveyance via CFPUA PS 12 to the Northside WWTP • Total Opinion of Probable Project Cost ranging from $5.6M to $6.OM Therefore, Alternative 2 is the most cost effective and advantageous solution to convey leachate from the proposed Duke Energy coal ash landfill and is the recommended alternative. END OF TECHNICAL MEMORANDUM Sutton Plant — Coal Ash Landfill Leachate Conveyance System Evaluation 19 Figures 1- 5 w cn ®� Z Z d Q w J W IL 0 z z LU W Cn L) wO =cn OA :) d U 0 LL aJz z a w 0 o � O C x J C/) W a zU COO 00 u z 0 Oav�� aoa � WW aWZv� zQ awl W= Y U I C 6' V W & REED DUKE ENERGY SUTTON PLANT LEACHATE CONVEYANCE SYSTEM FIGURE 3 ALTERNATIVE NO 7 PROPOSED SYSTEM NOT TO SCALE U) 0 §2 �0 §ILL Z 0 �u _ _ w �k LLJ ® �§E§ ( � ° \ Lu0 M ^ Lu \/ 0 � - \) mz /// \J E) m = \\ \\ } g y3 ®\ ° \ ( k � 2 � m \ ~/ a \e a o / \\/ \ / \\ \ 1 i // \/ /Q 2� 4 0 \a«3a :©vaa>V? :ey z>- ) 2 z§ \� �>w ) am ° o0 u} z� _ \ 0 �� r / §� Appendix A APPENDIX A - ALTERNATIVE 1 Hydraulic Calculations - 8 Inch Diameter Force main TDH Calculation Alternative 1 Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) Material Flow Rate (GPM) Velocity (FPS) HW'C' Value Friction Head (ft) 30,000 31,500 8 PVC 325 2.1 120 83.9 1,000 1,050 6.92 HPDE 325 2.8 120 5.7 Velocity Total Force Main Friction Head 89.6 Static Head Calculation Existing Ground 89.6 Minimum High Point of 59 Elevation @ Depth of Wetwell Water Level Discharge Total Satic Pump Station (ft) in PS Force Main Head (ft) 20 35 -15 44 59 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 89.6 ft Total Static Head 59 ft Total Dynamic /System Head 149 ft Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 149 ft HGL at Pump Station 134 ft Force Main Discharge Elevation 16 ft Total Head at Force Main Discharge 118 ft Pressure in Force Main 1 51 Ipsi Surge Pressure Calculation Alternative 1 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 1 Total Dynamic Head 149 ft Pump Rate 325 GPM Tota I 14 HP Recommended HP Surge Pressure HP Potential per 1 fps Surge Pipe Diameter Velocity Estimate Surge Working Pressure (inches) Velocity (FPS) Material Change (psi) ** Pressure (psi) Pressure (psi) (psi) 8 2.1 DR 18 PVC 1 17.4 36.54 50.9 87 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 1 Total Dynamic Head 149 ft Pump Rate 325 GPM Brake HP (Calculated) 14 HP Recommended HP 15 HP * *Recommended HP higher to provide for non - overload conditions for impeller range APPENDIX A - ALTERNATIVE 1 Hydraulic Calculations - 6 Inch Diameter Force main TDH Calculation Alternative 1 Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) Material Flow Rate (GPM) Velocity (FPS) HW 'C' Value Friction Head (ft) 30,000 31,500 6 PVC 325 3.7 120 339.9 1,000 1,050 6.92 HPDE 325 2.8 120 5.7 Velocity Total Force Main Friction Head 345.6 Static Head Calculation Existing Ground 345.6 Minimum High Point 58 Elevation @ Total Dynamic /System Head Water Level of Discharge Total Satic Pump Station Depth of Wetwell in PS Force Main Head (ft) 20 35 -15 43 58 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 345.6 Ift Total Static Head 58 ft Total Dynamic /System Head 404 1 ft Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 404 ft HGL at Pump Station 389 ft Force Main Discharge Elevation 20 ft Total Head at Force Main Discharge 369 Ift Pressure in Force Maini 160 Ipsi Surge Pressure Calculation Alternative 1 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 1 Total Dynamic Head ** 404 ft Surge 325 GPM Brake HP (Calculated) 41 HP Recommended HP Pressure per HP Total 1 fps Potential Velocity Surge Pipe Diameter Change Estimate Surge Working Pressure (inches) Velocity (FPS) Material (psi) ** Pressure (psi) Pressure (psi) (psi) 6 3.7 DR 18 PVC 17.4 64.38 159.6 224 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 1 Total Dynamic Head ** 404 ft Pump Rate ** 325 GPM Brake HP (Calculated) 41 HP Recommended HP 50 HP * *Review of commercially available pumps yielded no commercially publicized pumps that could meet these conditions and would require a series pumping configuration to meet these conditions Appendix B APPENDIX B - ALTERNATIVE 2 Hydraulic Calculations - 8 Inch Diameter Force main TDH Calculation Alternative 2 Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) I Material Flow Rate (GPM) Velocity (FPS) HW'C' Value Friction Head (ft) 37,000 38,850 8 PVC 325 2.1 120 103.4 35 Total Force Main Friction Head 103.4 Static Head Calculation Existing Ground 103.4 Minimum High Point of 59 Elevation @ Total Dynamic /System Head Water Level Discharge Total Satic Pump Station Depth of Wetwell in PS Force Main Head (ft) 20 35 -15 44 59 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 103.4 Ift Total Static Head 59 ft Total Dynamic /System Head 162 Ift Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 162 ft HGL at Pump Station 147 ft Force Main Discharge Elevation 16 ft Total Head at Force Main Discharge 131 ft Pressure in Force Main 1 57 Ipsi Surge Pressure Calculation Alternative 2 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 2 Total Dynamic Head 162 ft Pump Rate 325 GPM Tota I 15 HP Recommended HP Surge Pressure HP Potential per 1 fps Surge Pipe Diameter Velocity Estimate Surge Working Pressure (inches) Velocity (FPS) Material Change (psi) ** Pressure (psi) Pressure (psi) (psi) 8 2.1 DR 18 PVC 17.4 36.54 56.9 93 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 2 Total Dynamic Head 162 ft Pump Rate 325 GPM Brake HP (Calculated) 15 HP Recommended HP 20 HP * *Recommended HP higher to provide for non - overload conditions for impeller range APPENDIX B - ALTERNATIVE 2 Hydraulic Calculations - 6 Inch Diameter Force main TDH Calculation Alternative 2 Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) Material Flow Rate (GPM) Velocity (FPS) HW 'C' Value Friction Head (ft) 37,000 38,850 6 PVC 325 3.7 120 419.3 35 Total Force Main Friction Head 419.3 Static Head Calculation Existing Ground 419.3 Minimum High Point 58 Elevation @ Total Dynamic /System Head Water Level of Discharge Total Satic Pump Station Depth of Wetwell in PS Force Main Head (ft) 20 35 -15 43 58 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 419.3 Ift Total Static Head 58 ft Total Dynamic /System Head 477 Ift Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 477 ft HGL at Pump Station 462 ft Force Main Discharge Elevation 20 ft Total Head at Force Main Discharge 442 Ift Pressure in Force Maini 191 Ipsi Surge Pressure Calculation Alternative 2 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 2 Total Dynamic Head ** 477 ft Surge 325 GPM Brake HP (Calculated) 49 HP Recommended HP Pressure per HP Total 1 fps Potential Velocity Surge Pipe Diameter Change Estimate Surge Working Pressure (inches) Velocity (FPS) Material (psi) ** Pressure (psi) Pressure (psi) (psi) 6 3.7 DR 18 PVC 17.4 64.38 191.5 256 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation for Alternative 2 Total Dynamic Head ** 477 ft Pump Rate ** 325 GPM Brake HP (Calculated) 49 HP Recommended HP 60 HP * *Review of commercially available pumps yielded no commercially publicized pumps that could meet these conditions and would require a series pumping configuration to meet these conditions Appendix C APPENDIX C - OPTION DESIGN CONSIDERATION Hydraulic Calculations - 6 Inch Diameter Force main Reduced Flow 180 GPM /2.5 Peak = Max Day 103,680 GPD TDH Calculation 6 -Inch Force Main Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) Material Flow Rate (GPM) Velocity (FPS) HW 'C' Value Friction Head (ft) 30,000 31,500 6 PVC 180 2.0 120 108.5 1,000 1,050 6.92 HPDE 180 1.5 120 1.8 Velocity Total Force Main Friction Head 110.3 Static Head Calculation Existing Ground 110.3 Minimum High Point 58 Elevation @ Total Dynamic /System Head Water Level of Discharge Total Satic Pump Station Depth of Wetwell in PS Force Main Head (ft) 20 35 -15 43 58 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 110.3 Ift Total Static Head 58 ft Total Dynamic /System Head 168 Ift Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 168 ft HGL at Pump Station 153 ft Force Main Discharge Elevation 20 ft Total Head at Force Main Discharge 133 Ift Pressure in Force Main 1 57.7 Ipsi Surge Pressure Calculation 6 -Inch Force Main ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation 6 -Inch Force Main Total Dynamic Head ** 168 ft Surge 180 GPM Brake HP (Calculated) 10 HP Recommended HP Pressure per HP Total 1 fps Potential Velocity Surge Pipe Diameter Change Estimate Surge Working Pressure (inches) Velocity (FPS) Material (psi) ** Pressure (psi) Pressure (psi) (psi) 6 2 DR 18 PVC 17.4 34.8 57.7 93 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation 6 -Inch Force Main Total Dynamic Head ** 168 ft Pump Rate ** 180 GPM Brake HP (Calculated) 10 HP Recommended HP 10 to 15 HP APPENDIX C - OPTION DESIGN CONSIDERATION Hydraulic Calculations - 4 Inch Diameter Force main Reduced Flow 80 GPM /2.5 Peak = Max Day 46,080 GPD TDH Calculation 4 -Inch Force Main Force Main Friction Loss Calculation Length of Pipe 5% Line Length for Minor Losses Diameter (inches) Material Flow Rate (GPM) Velocity (FPS) HW 'C' Value Friction Head (ft) 30,000 31,500 4 PVC 80 2.0 120 182.8 1,000 1,050 6.92 HPDE 80 2.8 120 0.7 Velocity Total Force Main Friction Head 183.5 Static Head Calculation Existing Ground 183.5 Minimum High Point 58 Elevation @ Total Dynamic /System Head Water Level of Discharge Total Satic Pump Station Depth of Wetwell in PS Force Main Head (ft) 20 35 -15 43 58 Total Dynamic System Head Calculaton (TDH) Total Force Main Friction Head 183.5 Ift Total Static Head 58 ft Total Dynamic /System Head 241 Ift Hydraulic Grade Line & Force Main Pressure Calculation Wetwell Invert -15 ft Total System Head 241 ft HGL at Pump Station 226 ft Force Main Discharge Elevation 20 ft Total Head at Force Main Discharge 206 Ift Pressure in Force Mainj 89.4 Ipsi Surge Pressure Calculation 4 -Inch Force Main ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation 4 -Inch Force Main Total Dynamic Head ** 241 ft Surge 80 GPM Brake HP (Calculated) 6 HP Recommended HP Pressure per HP Total 1 fps Potential Velocity Surge Pipe Diameter Change Estimate Surge Working Pressure (inches) Velocity (FPS) Material (psi) ** Pressure (psi) Pressure (psi) (psi) 4 2 DR 18 PVC 17.4 34.8 89.4 124 ** Per Uni -Bell Handbook of PVC Pipe Horsepower Calculation 4 -Inch Force Main Total Dynamic Head ** 241 ft Pump Rate ** 80 GPM Brake HP (Calculated) 6 HP Recommended HP 15 to 20 HP APPENDIX B PowerPoint Presentation for CFPUA Board of Directors New Hanover County Commissioners L 0 %i L J N 41 3 s a� z U) D Fri �J ■ N ■ 11111111 L 3 as 0 L i lot O DC CF) LU s� i E NOMINEE 0 L y am Ga _31 GD Ca ri A (�j1 uA Q l bb S G H L 0 U i 0 m m a a LL V L .N .N E E V 4- L m 0 m 0 L r_ m 2 Z x 41) U) 0 i a 0 V .N M co L. a 06 CL v cry ca C7 .;. 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