EVALUATION MEMORANDUM NO. 4 Existing Pipeline Evaluation

Transcription

1 Orange County Water District Final Expansion of the Groundwater Replenishment System Project EVALUATION MEMORANDUM NO. 4 Existing Pipeline Evaluation July 23, 2018 Black & Veatch Project No

2 EVALUATION MEMORANDUM NO. 4 Existing Pipeline Evaluation To: From: Sandy Scott Roberts, P.E., Orange County Water District, GWRS Program Project Manager Steven N. Foellmi, P.E., Project Manager Prepared By: Andrew Stanton, P.E. Bryon Livingston Kristi Kuhlmann, P.E. Derek Wurst, P.E. Reviewed By: Steven N. Foellmi, P.E.

3 Table of Contents Executive Summary... ES Introduction and Background Overview Project Background and Purpose Project Description Project Scope Condition Assessment of Pipe Review of Existing Drawings Pipe Alignment Characteristics Rehabilitation Evaluation Process Condition Assessment Overview Review of 2012 CCTV Inspection CCTV Inspection Results Condition Assessment Conclusions Rehabilitation Methods Overview General Assumptions and Evaluation Criteria Initial Screening of Methods Cementitious Lining Sliplining with Fiberglass Reinforced Polymer Mortar Pipe Sliplining with HDPE Tight Fit Liners Using HDPE Cured in Place Pipe (CIPP) Liner (For Pressure Pipelines) Carbon Fiber Reinforced Polymer System (CFRP) Results of Initial Screening Comparative Analysis of Preferred Alternatives Overview Evaluation Approach Hydraulics Segmented Sliplining with FRP Continuous Sliplining with HDPE i

4 4.3.3 Tight Fit Liner with HDPE Service Life Segmented Sliplining with FRP Continuous Sliplining with HDPE Tight Fit Liner with HDPE Constructability Segmented Sliplining with FRP Continuous Sliplining with HDPE Tight Fit Liner with HDPE Environmental and Public Impacts Segmented Sliplining with FRP Continuous Sliplining with HDPE Tight Fit Liner with HDPE Cost Construction Cost Net Present Worth Commercial Risk Segmented Sliplining with FRP Continuous Sliplining with HDPE Tight Fit Liner with HDPE Summary of Alternatives Recommendations LIST OF TABLES Table ES 1. Rehabilitation Practices for Water Mains (from AWWA MOP M28)... ES 2 Table ES 2. Description of Evaluation Criteria... ES 3 Table ES 3. Comparison of Alternatives... ES 3 Table 2 1. Locations of 2012 CCTV Inspection Table 2 2. Locations of 2018 CCTV Inspection Table 3 1. Rehabilitation Practices for Water Mains (from AWWA MOP M28) Table 3 2. Design Requirements for Rehabilitation Table 3 3. Results of Preliminary Screening Table 4 1. Summary of Alternatives Ranking System Table 4 2. Description of Evaluation Criteria Table 4 3. Description of Evaluation Criteria ii

5 Table 4 4. Construction Cost Comparison Table 4 5. Present Worth Calculations Input Table 4 6. Net Present Worth for Energy Cost of Pumping for Each Alternative Table 4 7. Net Present Worth of Each Alternative Table 4 8. Comparison of Alternatives LIST OF FIGURES Figure 1 1. Layout of Interplant Pipeline Figure 1 2. Bike Path and River Along Pipe Alignment Figure 2 1. Schematic Showing Extent of 2012 and 2018 CCTV Inspections Figure 2 2. Example of Sediment Build Up in Pipe Figure 2 3. Damaged Liner Figure 2 4. Exposed Rebar in Some Locations Figure 2 5. Standard CCTV Crawler Figure 2 6. Panorama CCTV Crawler Figure 2 7. Sediment Upstream of MH (2018 Inspection) Figure 2 8. Area of Rust Between MH and MH (2018 Inspection) Figure 2 9. Layout of Existing Siphon Figure 3 1. Cement Mortar Lining Process Figure 3 2. Sliplining Process Figure 3 3. Ackerman Machine for Pushing Pipe Figure 3 4. Continuous Sliplining Process Figure 3 5. Swagelining Process Figure 3 6. Cured in Place Rehabilitation Process Figure 3 7. Cured in Place Rehabilitation Process Figure 4 1. Representative Cross Sections for the 66 inch Pipeline Alignment Figure 4 2. Flush Joint for FRP Figure 4 3. Comparison of Annual Power Costs LIST OF EQUATIONS Equation 4 1. Flow Calculation for Segmented Sliplining Pipe Equation 4 2. Flow Calculation for Continuous Sliplining with HDPE Equation 4 3. Flow Calculation for Tightfit Liner with HDPE LIST OF APPENDICES A Summary of 2012 CCTV Inspection iii

6 ABBREVIATIONS AND ACRONYMS The following acronyms and abbreviations are used in this document. AWTF Advanced Water Treatment Facility AWWA American Water Works Association Black & Veatch Black & Veatch Corporation Basin Orange County Groundwater Basin CCTV closed circuit television CFRP carbon reinforced polymer system CIP clean in place CIPP cured in place pipe CML cement mortar lined District Orange County Water District DR pipe dimension ratio [average OD/ minimum pipe wall thickness] SEJB Secondary Effluent Junction Box EM evaluation memorandum Expansion Project Ground Water Replenishment System Final Expansion FRP fiber reinforced polyethylene ft feet ft 2 square feet ft 3 cubic feet GWRS Groundwater Replenishment System GWRSFE GWRS Final Expansion GWRSIE GWRS Initial Expansion H 2 S hydrogen sulfide HDPE high density polyethylene ID inside diameter Lbs/ft2 pounds per square foot lbs/hr pounds per hour lb/m pounds per minute MH manhole m meter MF microfiltration MG million gallons mgd million gallons per day MOP manual of practice O&M operations and maintenance OCFCD Orange County Flood Control District OCSD Orange County Sanitation District OCWD Orange County Water District OD outside diameter OOBS Ocean Outfall Booster Station P 1 OCSD Plant No. 1 P 2 OCSD Plant No. 2 PDWF peak dry weather flow P2 SE Plant 2 Secondary Effluent PDR Preliminary Design Report Plant 1 OCSD Reclamation Plant 1 Plant 2 OCSD Treatment Plant 2 iv

7 Project ProPipe psi RC SAR SE GWRS Final Expansion ProPipe Professional Pipe Services pounds per square inch reinforced concrete Santa Ana River secondary effluent v

8 EXECUTIVE SUMMARY PURPOSE The Orange County Water District (OCWD, District) and the Orange County Sanitation District (OCSD) are partners in the Groundwater Replenishment System (GWRS) Project, an innovative, award winning water supply program to maximize local resources. OCWD and OCSD are currently embarking upon the Final Expansion of the GWRS (GWRSFE, Final Expansion, Expansion Project, Project), which will increase the capacity of the Advanced Water Treatment Facility (AWTF) from 100 million gallons per day (mgd) to 130 mgd. The Project also will include new secondary effluent (SE) facilities at OCSD Treatment Plant 2 (Plant 2, P2) and a pipeline rehabilitation component. OCWD authorized Black & Veatch Corporation (Black & Veatch) to perform predesign, final design, and bid phase services for the Project. The scope of work includes development of six evaluation memoranda (EMs) to document major project decisions. The purpose of this EM 4 is to assess the condition of the existing Orange County Sanitation District (OCSD) 66 inch reinforced concrete (RC) pipeline to be used to convey secondary effluent from P2 to the AWTF. SCOPE The AWTF currently treats effluent from OCSD Plant No.1 (Plant 1, P1). The GWRSFE will require both process improvements at the AWTF and additional source water from OCSD. The new source water will be pumped to the AWTF from OCSD s Plant 2. EMs 1 through 3 evaluated impacts of the changes in source water on the AWTF. This EM 4 assesses the conveyance pipeline and recommends pipeline rehabilitation alternatives. FINDINGS Findings presented in this EM are highlighted below. Condition Assessment The CCTV inspection in 2012 had gaps over the length of the pipeline and about 5,000 feet were not inspected. During review of the 2012 CCTV records, no major structural impediments to pipeline rehabilitation were observed throughout the portion of the pipeline inspected. However, various issues were identified during the review of the CCTV inspection records. Additional CCTV inspection was conducted by ProPipe Professional Pipe Services (ProPipe) in April 2018 to inspect the pipe sections not covered in From the results of the 2012 and 2018 condition assessments, it was concluded that there are no major defects along the alignment in the inspected portions that will significantly impact the rehabilitation of the pipeline. The observed pipe joints appear to be in alignment and no deflections were observed in the pipe. The issues identified in the inspection can be addressed during the design and construction of the rehabilitation. The three short segments of pipe that were not inspected collectively are less than 5 percent of the entire pipeline section to be rehabilitated. Based upon the consistency of the defects observed throughout the remaining segments, it can reasonably be assumed there are no major defects in those segments. ES 1

9 Evaluation of Pipeline Rehabilitation Alternatives The selection of a method for rehabilitation must take into account several factors. These factors include: (1) the purpose for the rehabilitation indicating structural or semi structural methods, (2) the operating conditions, internal and external loadings, and flow capacity required, and (3) locations of appurtenances, access manways, air release valves, blowoffs and bends. A range of rehabilitation methods available for rehabilitation of the 66 inch pipeline was preliminarily screened down to the three most viable methods, as listed in Table ES 1. Table ES 1. Rehabilitation Practices for Water Mains (from AWWA MOP M28) REHABILITATION METHOD CUSTOM DESCRIPTION COMMENTS Cement Mortar (including the geopolymer) Spray applied cement mortar requires reinforcement to make semi structural Discussed in Section Epoxy/Polyurethane Generally considered non structural Not considered applicable Segmented Sliplining Sliplining with Fiberglass Pipe (such as HOBAS and Flowtite) Discussed in Section Continuous Sliplining With HDPE (high density polyethylene) Discussed in Section Tight Fit Liners Using HDPE (Swagelining tight liner and roll down methods) Discussed in Section CIPP Requires layers of liner for pressure pipeline Discussed in Section Structural Lining Carbon Fiber Reinforced Polymer (CFRP) Discussed in Section Internal Joint Seals Would not address deterioration along the pipe wall and does not provide a fully structural liner Not considered applicable Pipe Bursting Not available in required diameter Not considered applicable Of the nine methods identified, three were determined to not be appropriate for the scope of this project. The remaining six alternatives were screened against evaluation criteria to ultimately identify the three alternatives carried forward for further evaluation. The alternatives include: Segmented sliplining with FRP Continuous sliplining with HDPE Tight fit liner with HDPE In addition to the discussion in this EM, these methods will be evaluated in the PDR, which will address specific issues such as type and location of access, thickness of material, final hydraulic impacts, and ultimately which method to include in the bid documents. The three alternatives were scored against the six criteria outlined in Table ES 2 using a 1 to 5 scoring system. The total score for each alternative is shown in Table ES 3. ES 2

10 Table ES 2. Description of Evaluation Criteria CRITERION Hydraulics Service Life Constructability Potential Environmental and Public Impacts Costs Commercial Risk DESCRIPTION Evaluation using current information available on the existing pipe, assuming 25 psi. Friction factors based on engineering judgment and published reports. Estimation of possible impacts on pipe material from corrosion resulting from exposure to possible soil and water contaminants. Abrasion resistance estimated from public information and general deterioration that could impact pipe material. Comparison of accessibility with equipment, modifications to piping such as removing a section of pipe for construction of an access pit with trench box and excavations, and any other factors that could impact the construction schedule, availability of products, or design of the pipeline. Comparison of environment and public factors included in the environmental documentation, traffic impacts, OC Flood Control District coordination, Santa Ana River bike path impacts, etc. Comparison of estimated construction cost (conceptual) and net present worth to implement the proposed method. Comparison of availability of pipe vendors and contractors with proven track record for work of this nature. Table ES 3. Comparison of Alternatives ALTERNATIVE HYDRAULICS SERVICE LIFE CONSTRUCTABILITY ENVIRONMENTAL & PUBLIC No. 1 Segmented Sliplining with FRP No. 2 Continuous Sliplining with HDPE No. 3 Tight Fit Lining with HDPE COST COMMERCIAL RISK TOTAL ES 3

11 CONCLUSIONS AND RECOMMENDATIONS Based on the evaluation, the following approach is recommended: 1. The evaluation shows that there is little to differentiate between segmented sliplining with FRP and continuous sliplining with HDPE. Both are technically feasible options which satisfy each project objective and evaluation criteria. We recommend that the design be developed and the pipeline rehabilitation bid using both options and allowing market forces to drive the final selection. This would ensure the most competitive bid while still satisfying the project requirements. 2. The reduction in energy costs for utilizing a tight fit liner does not compensate for the increased construction cost. In addition, this alternative has a substantial potential commercial risk. For these reasons, this option is not recommended. ES 4

12 1.0 Introduction and Background 1.1 OVERVIEW This section presents the background and purpose of the GWRSFE. Also provided are a brief Project description, a summary of the project scope, and a general description of the rehabilitation evaluation process. 1.2 PROJECT BACKGROUND AND PURPOSE The GWRS is a water supply project constructed by OCWD and OCSD. The system extends from Huntington Beach and Fountain Valley near the coast to Santa Ana, Orange, and Anaheim generally along the Santa Ana River (SAR). The three major components of the GWRS are: the AWTF, located in Fountain Valley, a major pipeline and pumping stations connecting the AWTF to existing recharge basins; and an existing seawater intrusion barrier system. The GWRS supplements existing water supplies by providing a reliable, high quality source of water to recharge the Orange County Groundwater Basin (Basin) and to protect the Basin from further degradation due to seawater intrusion. By recycling water, the system also provides peak wastewater flow disposal relief and indefinitely postpones the need for OCSD to construct a new ocean outfall by diverting treated wastewater flows that could otherwise be discharged to the Pacific Ocean. The GWRS AWTF has been operating successfully since January The original design of GWRS included facility sizing and spacing for two phases of 30 mgd treatment capacity expansions to the AWTF. An Initial Expansion project (GWRSIE), completed in June 2015, brought the AWTF treatment capacity from 70 mgd to 100 mgd. The GWRSFE will increase the capacity to 130 mgd. 1.3 PROJECT DESCRIPTION The GWRSFE consists of two project elements to be executed through two separate design bidbuild construction contracts. Element One is comprised of the AWTF Expansion and the Plant 2 Secondary Effluent (P2 SE) Facilities. Element Two is the Pipeline Rehabilitation Project. Design of both elements will be coordinated with other construction projects at both OCWD and OCSD. Preliminary design for Element One is completed and is presented in Preliminary Design Report (PDR) Volume 1. Preliminary design for Element Two is underway and will be presented in PDR Volume 2. Element Two includes the sliplining of the existing 66 inch interplant pipeline with a new pipeline from Plant 2 to Plant PROJECT SCOPE The GWRSFE scope of work entails performance of all design and associated work necessary to prepare complete construction drawings and specifications; develop process control systems, control system strategies and their integration into the existing control system; and utility coordination, surveying, and geotechnical work. This Evaluation Memorandum (EM) reviews available methods of pipe rehabilitation to determine those that could be feasible for use to repair and rehabilitate the 66 inch reinforced concrete abandoned interplant pipeline. The section of the 66 inch pipeline to be rehabilitated will be about 1 1

13 15,750 feet (ft) between the point of connection to the P2 SE Facilities and the Plant 1 as shown in Figure Condition Assessment of Pipe The purpose of the condition assessment is to gather data to determine the condition of the existing pipe focusing on the potential impacts for choice of rehabilitation technique. The repurposing of the pipeline from a gravity to a pressure system necessitates rehabilitation regardless of the structural condition of the existing pipe and given the criticality of this pipeline to the operation of the AWTF, a fully structural liner is required. Thus, determining the structural condition and estimating the remaining service life of the existing 66 inch pipeline was not a focus of the condition assessment. The condition assessment was conducted in two phases: 1) an initial review of closed circuit television (CCTV) from a previous inspection conducted in 2012 and 2) additional inspection in 2018 to fill in for missing areas in the 2012 inspection. The 2018 inspection specifically focused on joint alignment, defects that would require repair prior to rehabilitation, and defects that would impede the rehabilitation method Review of Existing Drawings The pipeline was constructed in 1967 and is about 19,000 feet of 66 inch reinforced concrete pipe and runs between and within Plant 1 and Plant 2. Of this, approximately 15,750 feet is proposed to be rehabilitated and repurposed, with the remainder abandoned in place. A segment of the pipeline was relocated in 1991 to accommodate the installation of a new 120 inch interplant pipeline. This work resulted in the siphon located between manhole (MH) and The location of the new pump station will not require the entire pipeline to be reused. The section of pipeline to be reused is from station to The record drawings show a total of ten manholes along the 19,000 feet length; two are 66 inch diameter manways, and the rest are 24 inch manways. However, of these smaller manways, one is no longer in existence. MH was demolished at the time that the Effluent Junction Box (EJB) was constructed just south of Plant 1 near Garfield Avenue. In addition, OCSD maintenance staff and the inspection teams have been unable to relocate MH Based on discussions with OCSD staff, Black & Veatch s understanding is that MH might have been covered over since the 2012 inspection. MH has been covered by the access ramp for the bike path alongside the SAR. 1 2

14 Figure 1 1. Layout of Interplant Pipeline Pipe Alignment Characteristics The pipeline is located in OCSD s easement along the embankment next to SAR, adjacent to the Orange County Flood Control District (OCFCD) easement and the bike path, which makes access limited as shown in Figure 1 2. Figure 1 2. Bike Path and River Along Pipe Alignment The area is bounded by homes, businesses, and roadways along the entire alignment. The manholes are accessible. Vehicular access to the pipeline alignment is limited to points of access into the OCFCD easement. 1 3

15 1.5 REHABILITATION EVALUATION PROCESS The selection of a method for rehabilitation must take into consideration several factors. These factors include the condition of the pipeline, design service life, access to the pipe, hydraulic impacts, and cost. The rehabilitation evaluation for this EM consisted of the following steps: A review of the 2012 condition assessment and an updated (2018) condition assessment, as described in Section 2. A review of potential rehabilitation methods and selection of specific methods for preliminary screening, as described in Section 3. Development of three preferred alternatives, as discussed in Section 4. Development of recommendations, as presented in Section

16 2.0 Condition Assessment 2.1 OVERVIEW This section presents results of the Black & Veatch review of the 2012 condition assessment and describes the subsequent 2018 Black & Veatch inspection of areas not covered in Conclusions are then presented on the results of both inspections. 2.2 REVIEW OF 2012 CCTV INSPECTION The CCTV inspection in 2012 had gaps over the length of the pipeline and about 5,000 feet were not inspected as shown in Figure 2 1 and listed in Table 2 1 below. In addition to the as built drawings we reviewed the alignment on the map books used by operations to locate the pipeline. Figure 2 1 shows the location of the existing manholes using both the station shown on the as built drawings and also the reference system used in the 2012 inspection for ease of reference. Sections of pipeline surveyed in 2012 are shown in blue, together with the approximate extent of the pipeline to be rehabilitated. The downstream station of reflects the agreed (revised) location of the P2 SE facilities after adjustment of the pump station location further to the north of Plant 2. The 2012 inspection records indicate that sediment in the pipe limited this inspection to the extent shown on Figure 2 1. There were also sections where the water level was over 35 percent, which prevented the invert and significant portions of the pipe wall from being inspected. Table 2 1. Locations of 2012 CCTV Inspection UPSTREAM MH DOWNSTREAM MH MAP BOOK LENGTH MISSING LENGTH NOTES Filmed from No Video Required Reverse Setup Required Reverse setup Siphon S / Siphon N Siphon S Siphon N / No Video No Video 2 1

17 Figure 2 1. Schematic Showing Extent of 2012 and 2018 CCTV Inspections 2 2

18 GWRS Final Expansion EM4 OCWD During review of the 2012 CCTV records, no major structural impediments to pipeline rehabilitation were observed throughout the portion of the pipeline inspected. However, various issues were identified during the review of the CCTV inspection records noted below. A complete summary of the inspection results from the 2012 inspection is included as Appendix A. The main concerns identified in this inspection were the amount of sediment in several locations that restricted the inspection. An example of the sediment between MH and MH is shown in Figure 2 2. Figure 2 2. Example of Sediment Build Up in Pipe Other observations include the exposed aggregate throughout significant sections of the inspected pipeline, especially along the crown of the pipe, some areas of defects in the liner shown in Figure 2 3, and areas of exposed rebar shown in Figure 2 4. The extent of exposed rebar indicates that the existing pipeline may be structurally compromised and reaffirms the need for a fully structural liner system to be installed. 2 3

19 Figure 2 3. Damaged Liner Figure 2 4. Exposed Rebar in Some Locations 2 4

20 CCTV INSPECTION RESULTS Additional CCTV inspection was conducted by ProPipe Professional Pipe Services (ProPipe) in April 2018 to inspect the pipe sections not covered in ProPipe provided a cleaning truck during the inspection to address the potential for debris within the pipeline. Support services were provided by a contractor (Jamison Engineering Contractors, Inc.) including removal of locked manhole covers to provide CCTV access into the pipe. The inspection was conducted using a standard CCTV crawler shown in Figure 2 5 and a Panorama 360 degree CCTV crawler shown in Figure 2 6. The Panorama crawler collects digital images of the entire pipe that allows the reviewer to pan and zoom as desired to view portions of the pipe as needed. Figure 2 5. Standard CCTV Crawler 2 5

21 Figure 2 6. Panorama CCTV Crawler The extent of the 2018 CCTV inspection is shown on Figure 2 1 in orange and in Table 2 2. The inspection crews were unable to locate either MH or MH , as reported in Section A combination of lack of access to these manholes and sediment within the pipe prevented complete coverage of the 66 inch pipeline. The sections not inspected are shown in red on Figure 2 1. Table 2 2. Locations of 2018 CCTV Inspection UPSTREAM MH DOWNSTREAM MH LENGTH (FT) NOTES Est. EJB 612 Approximate location of EJB Siphon N 480 Abandoned; Unknown debris prevented progress Siphon S 711 Abandoned; Unknown debris prevented progress OOBS 825 Abandoned; Unknown debris prevented progress Completed area of interest Duplicate inspection for evaluation of video quality The 189 feet downstream of MH was not inspected. The debris in the pipe from MH towards the OOBS limited the inspection to 825 feet resulting in about 1,200 feet of pipe not inspected. Without MH , there was no access for a reverse inspection and the distance was just past the 800 foot capability of the cleaning truck equipment. OCSD operations staff modified the flow regime in the OOBS wet well to allow the water level in the segment between MH and OOBS to drop to less than 18 inches. This allowed the inspection of that segment of the pipe with the standard CCTV camera. Because the panorama crawler can 2 6

22 only be raised to 18 inches, the standard CCTV crawler was used for inspection of this pipe segment. The other segments were inspected using the panorama inspection camera. The observations from the 2018 inspection are consistent with the 2012 inspection. Surface aggregate was exposed and there were several areas with large amounts of sediment buildup as shown in Figure 2 7 and some areas of rust showing through as shown in Figure 2 8. Figure 2 7. Sediment Upstream of MH (2018 Inspection) Figure 2 8. Area of Rust Between MH and MH (2018 Inspection) 2 7

23 2.4 CONDITION ASSESSMENT CONCLUSIONS From the results of the 2012 and 2018 condition assessments, it was concluded that there are no major defects along the alignment in the inspected portions that will significantly impact the rehabilitation of the pipeline. The observed pipe joints appear to be in alignment and no deflections were observed in the pipe. The issues identified in the inspection can be addressed during the design and construction of the rehabilitation. The three short segments of pipe that were not inspected collectively are less than 5 percent of the entire pipeline section to be rehabilitated. Based upon the consistency of the defects observed throughout the remaining segments, it can reasonably be assumed there are no major defects in those segments. Sediment removal will be a major factor in the construction of the rehabilitation regardless of which method is selected. The majority of the sediment appears to be a mixture of gravel and fine particles. Jamison Engineering Contractors, Inc. conducted a confined space manned entry into the pipe at MH to collect a grab sample of the sediment for testing. During this entry, no odors were reported when disturbing the material to collect the sample. Potential for hydrogen sulfide (H 2 S) may still be a concern but it appears that the debris is no longer biologically active. The disposal of the sediment will be determined by the contractor, but will require that additional information be obtained during the design process. A significant length of the pipeline crown was missing aggregate. The depth of the wall loss was not measured. This defect would be a concern if the rehabilitation method is cured in place pipe (CIPP). The soundness of the concrete could not be determined from visual inspection. Aggregate was exposed or missing along most of the alignment. This could impact the pulling or pushing of the liner pipe by scraping off aggregate that could damage the liner pipe or create a point of pressure if wedged between the host and liner pipe. The section of the pipe past the pump station will require plugging as part of the abandonment for that section of pipe. The existing liner in the siphon and other areas that are damaged and hanging down will have to be removed prior to the rehabilitation of the pipe. The siphon will require detailed evaluation during the design process to determine the most effective rehabilitation method. The layout of the existing siphon is shown in Figure 2 9. The degree of deflection will have to be reviewed during the design process. This will include discussions with the pipe manufacturer to determine the best approach for lining through the siphon. 2 8

24 Figure 2 9. Layout of Existing Siphon 2 9

25 3.0 Rehabilitation Methods 3.1 OVERVIEW This section reviews a range of rehabilitation methods available for rehabilitation of the 66 inch pipeline and presents a preliminary screening of the most viable methods. Following the screening, three methods are carried forward to Section 4.0 for more detailed development and analysis. The selection of a method for rehabilitation must take into account several factors. These factors include: (1) the purpose for the rehabilitation whether for structural or corrosion protection, (2) the operating conditions, internal and external loadings, and flow capacity required, and (3) locations of appurtenances, access manways, air release valves, blow offs and bends. The rehabilitation methods described herein are classified as non structural (Class I), semistructural (Class II/III), or structural (Class IV). The American Water Works Association (AWWA) Manual of Practice (MOP) M28 Rehabilitation of Water Mains identifies several methods to rehabilitate water mains. These are listed in Table 3 1. As shown in the table, three of these methods were not considered appropriate for evaluation. The table also shows the remaining methods that underwent the preliminary screening. These methods were reviewed because they can be installed at various design thicknesses and therefore could be semi structural or fully structural. Table 3 1. Rehabilitation Practices for Water Mains (from AWWA MOP M28) REHABILITATION METHOD Cement Mortar (including the geopolymer) CUSTOM DESCRIPTION Spray applied cement mortar requires reinforcement to make semi structural COMMENTS Discussed in Section Epoxy/Polyurethane Generally considered non structural Not considered applicable Segmented Sliplining Sliplining with Fiberglass Pipe (such as HOBAS and Flowtite) Discussed in Section Continuous Sliplining With HDPE (high density polyethylene) Discussed in Section Tight Fit Liners Using HDPE (Swagelining tight liner and roll down methods) Discussed in Section CIPP Requires layers of liner for pressure pipeline Discussed in Section Structural Lining Carbon Fiber Reinforced Polymer (CFRP) Discussed in Section Internal Joint Seals Would not address deterioration along the pipe wall and does not provide a fully structural liner Not considered applicable Pipe Bursting Not available in required diameter Not considered applicable 3 1

26 A lining that is fully structural is one that will withstand internal and external loads imposed on the pipe without additional support from the host pipe, essentially a new pipe within the old one. A semi structural lining is one that relies on some residual strength from the host pipe to support loads. It is not capable of withstanding the full internal pressure, but can span across small holes or cracks in the host pipe, thus providing a fully structural pipe that is a composite of the host pipe and the lining. A non structural lining is one that does not provide any structural enhancement to the host pipe, but does provide a barrier that protects the host pipe from further deterioration from internal corrosion to extend the life of the pipe. 3.2 GENERAL ASSUMPTIONS AND EVALUATION CRITERIA The lining system will be required to span the space between joints and provide new manhole access openings. The review of rehabilitation alternatives will include meeting the requirements for the existing conditions. The basic design parameters are listed in Table 3 2. Table 3 2. Design Requirements for Rehabilitation DESIGN PARAMETER Host Pipe Internal Working Pressure Occasional Surge Pressure (Emergency Shutdown) Soil Depth (maximum above crown) VALUE 66 inch Reinforced concrete pipe 25 psi 50 psi 10 feet Soil Density 120 lbs/ft 3 Ground Water Depth (below ground surface) 10 feet Live Load, general alignment 0 Live Load, road crossings Modulus of Soil Reaction H 20 loading 1,000 psi Soil Support Factor 1.0 Liner System Design Service Life Fully structural (Class IV) 50 years The impacts to the hydraulic capacity of the pipeline from the rehabilitation will be evaluated and included as part of the overall recommendation. The rehabilitation alternatives will be evaluated based on the following: Impacts to the flow capacity based on projected hydraulics (minimum flow capacity 60 mgd) Structural service life (corrosion, abrasion, deterioration factors) Constructability Potential environmental and public impacts 3 2

27 The hydraulic evaluation will include a calculation of the flow capacity based upon the remaining inside diameter of the rehabilitated pipe. The service life of the pipe will consider the effects of corrosion and deterioration factors on the pipe material, and constructability will review those factors that are associated with construction of the rehabilitated pipeline. The environmental and public impacts will evaluate the factors that are associated with the construction process. 3.3 INITIAL SCREENING OF METHODS Many available methods can be used for rehabilitation of pipelines, using a wide variety of technologies. This subsection reviews the methods listed in Table 3 1 using the assumptions and criteria described in Section Cementitious Lining Cement mortar lining (CML) is one of the oldest pipeline rehabilitation methods and has been used to form non structural corrosion protection linings in a large range of pipe diameters. This methodology covers the application of treated or untreated cement mortar applied as a liner by a centrifugal spray or a projectile method. In the centrifugal method the cement mortar is applied by compressed air through a spinning head and the mortar is pumped to the unit through the supply hose as shown in Figure 3 1. The thickness of the liner is dependent upon the diameter and type of defect to be rehabilitated. The hoses and spray head are reeled in at a controlled rate towards the lining rig to provide the correct thickness of the lining. The design can include the addition of reinforcement of wire mesh or rebar for semi structural rehabilitation. This process is covered by the AWWA MOP. The design is based on AWWA Standard C602. The design can be for a non structural or semi structural liner. CML is relatively inexpensive and has Figure 3 1. Cement Mortar Lining Process demonstrated good corrosion protection in water pipelines under most operating conditions. The design guideline for pipelines suggests that CML can be used successfully for velocities up to 20 feet per second. In operations subject to higher velocities, CMLs have a tendency to be less resistant to abrasion and wear away. However, CML can be designed to have a wide range of resistance to abrasion depending on the type and amount of aggregate as well as the smoothness of the lining surface. Prior to the design of the mortar mix, the water quality is tested for constituents that could react with the cement mortar. Special cements and mortar mixes or additives can be specified if the water is aggressive. Cement mortar linings are highly alkaline and protect the pipe against corrosion. Because of its high compressive strength and arch action, in theory, CML is not dependent on bonding to the interior of the pipe wall. Bonding exists however which adds to the margin of safety of the ring stiffness. 3 3

28 In order to field apply CML, it is necessary to create access openings in the pipe for the centrifugal machine and necessary equipment to be lowered into the pipe. The pipe would have to be cleaned with a water blast or other method to remove any loose material prior to rehabilitation. CML is a relatively fast, one coat application, but is limited by post cure requirements involving periods of curing by moisture, heat, or a combination of the two. Also, CML must be kept in continuous moist conditions or irreversible cracks can develop, which could lead to significant liner damage. To make CML a semi structural rehabilitation, reinforcement would be required. The reinforcement could be wire fabric, spiral wire, or ribbon mesh, which is tack welded to the clean pipe interior. The mesh reinforced CML is thicker and would negatively impact the hydraulics of the rehabilitation by reducing the inside diameter of the pipe. Advantages of CML include: Time tested method. Several contractors available. Retains majority of the cross sectional area. Disadvantages of CML include: Distance for pumping concrete is limited to less than 1,000 feet. Extension of design life is a function of construction methods. Curing requirements are extensive. Does not provide a fully structural lining system. Does not improve flow characteristics. The use of CML is not considered feasible for the rehabilitation of the pipeline because of the disadvantages listed above. The diameter of the rehabilitated pipe would be reduced by several inches and the concrete would not provide an improvement in the flow characteristics. Also, construction would require additional excavations for access to the pipe based on the limited length of hose used for application of the material Sliplining with Fiberglass Reinforced Polymer Mortar Pipe The segmented process of sliplining involves the installation of a new pipe within the existing host pipe as shown in Figure 3 2. Generally, the new pipe is at least one size smaller than the host pipe. The liner pipe materials provide the required structural strength for fully structural replacement. The liner pipe material is designed to meet the required design loadings to provide a fully structural replacement. The length of each pipe joint is typically 20 feet, but it can be furnished in 40 foot sections. Also, shorter sections of pipe are used to negotiate some curves in the alignment. Figure 3 2. Sliplining Process 3 4

29 Fiberglass Reinforced Polymer Mortar Pipe is produced by HOBAS or Flowtite; the main difference is the casting process. HOBAS is made using a centrifugal casting process where the pipe wall structure is built up from the outside surface to the interior with a revolving mold. In constrast, Flowtite pipe is produced on a continuously advancing mandrel. The pipe is a glass fiber reinforced, aggregate fortified thermosetting resin made of several layers. The wall structure can be built to meet the stiffness and compressive load design requirements for most applications. The pipe can be manufactured in various lengths and diameters to meet specific conditions. The pipe joints are designed to meet the specific conditions to allow for pushing into the host pipe. Figure 3 3 shows the pipe being pushed with an Ackerman machine, but the pipe can also be pushed with a backhoe or other equipment. Figure 3 3. Ackerman Machine for Pushing Pipe After the liner is inserted into the host pipe, the annular space is grouted using a mix design to provide the required strength to support the pipe. This is installed from the inside of the pipe using grout ports that are installed along the pipeline or by using feeder tubes that are installed in the annular space. The grout mix is pumped into the annular space and provides support to the liner pipe. The segmented process of sliplining with reinforced fiberglass pipe is a feasible method for rehabilitation of the pipeline. The method should not require additional intermediate excavations for access pits and provides improved flow characteristics to partially offset the loss of diameter. The following is a typical sequence of construction events: 1. Construction of the insertion and receiving pits. 2. CCTV of host pipe to confirm location of bends or obstructions. 3 5

30 3. Cleaning of host pipe. 4. The pipe is stored off site and only the amount required is brought to the site. 5. The push head is placed on the pipe to protect the pipe being installed. 6. The pipe is placed in the access pit and the pipe pushed into the host pipe with a backhoe or Ackerman machine. 7. Access fittings are connected or installed along the alignment. 8. Liner pipe is pressure tested. 9. Restoration of site. The advantages to sliplining include: Segments of pipe can be rehabilitated from access with minimal space required. No special equipment for installation is required. Slight curves in the alignment can be negotiated. The disadvantages to sliplining include: Loss of cross sectional area reduces flow capacity. Grouting of the annular space is required. Requires installation of access manways and connections require special fittings. The use of segmented sliplining is a feasible method for rehabilitation of the pipeline. The major concern with construction of sliplining is the clearance between the host pipe and the liner to prevent damage to the new pipe and grouting of the annular space Sliplining with HDPE The continuous process of sliplining involves the installation of a new pipe within the existing host pipe as shown in Figure 3 4. The liner pipe materials provide the required structural strength for fully structural replacement. The liner pipe material is designed to meet the required design loadings to provide a fully structural replacement. The length of the continuous process is determined based on the alignment of the pipe and can be as long as several thousand feet. The continuous process cannot go through bends, but can negotiate curves in the alignment. 3 6

31 Figure 3 4. Continuous Sliplining Process The pipe dimension ratio (DR), the ratio of the average outside diameter of the polyethylene pipe divided by the minimum pipe wall thickness, will be determined as part of the design process and will be required to meet the design criteria for a fully structural pipe. HDPE pipe provides a monolithic, fully restrained, gasket free, and leak free piping system. However, HDPE requires special fittings for connections. The fusion process to join the pipe is called butt welding and is a type of hot plate welding. This technique involves heating two planed surfaces of thermoplastic material against a heated surface. After a specified amount of time, the heating plate is removed, and the two pieces are pressed together and allowed to cool under pressure, forming the desired bond. The use of continuous sliplining is a feasible method for rehabilitation of the pipeline. The method will not require additional intermediate excavations for access pits and provides improved flow characteristics to partially offset the loss of diameter. The following is a typical sequence of construction events: 1. Construction of the insertion and receiving pits. 2. CCTV of host pipe to confirm location of bends or obstructions. 3. Cleaning of host pipe. 4. Assembly of the HDPE pipe using butt fusion into pipe strings to match the spacing of the insertion pits. 5. The pipe is placed on the rollers. 6. The pull head is placed on the pipe for continuous lining. 7. The winch or static equipment is placed in the receiving pit and the pipe pulled through. 3 7

32 8. Connections established to restore blow off and air release valves. 9. Liner pipe is pressure tested. 10. Restoration of site. The advantages to sliplining include: Segments of pipe can be rehabilitated from access with minimal space required. No special equipment for installation is required. Slight curves in the alignment can be negotiated. The disadvantages to sliplining include: Loss of cross sectional area reduces flow capacity. Grouting of the annular space is required. Requires installation of access manways and connections require special fittings. The major concern with construction of sliplining is the clearance between the host pipe and the liner to prevent damage to the new pipe and grouting of the annular space Tight Fit Liners Using HDPE The Swagelining, TightLiner, and RollDown methods are all semi structural and structural, depending on the thickness of the HDPE material. The process used by these methods involves the running of the inserted pipe through a die or rollers to slightly reduce the pipe diameter and allow it to be pulled through the host pipe. The liner is kept under tension, which maintains the reduced diameter allowing it to pass through the existing pipe. Once through, the tension is relieved, and the new lining will elastically recover to its original dimensions. The Swagelining process is shown in Figure 3 5. The liner would be a tight fit HDPE pipe based upon the AWWA M55 design manual. Figure 3 5. Swagelining Process 3 8

33 The pipe DR would be determined as part of the design process and would be required to meet the design criteria for a fully structural pipe. This option would stop leaks, span holes, provide internal corrosion protection, provide enhanced structural support and increase the C value. The hydraulics for polyethylene liners have improved flow characteristics and an increase in flow capacity resulting from the improved friction factor. The flow loss from the reduced diameter is partially recovered in the improved flow characteristics. The final design would have to evaluate the impact of the liner on the hydraulics. The long insertion pits would require close evaluation in determining the segments for this alternative. The lay down area along the alignment may require some clearing of vegetation. The use of tight fit liner methods of Swagelining, TightLiner and RollDown are feasible methods for rehabilitation of the pipeline. The existing pipeline, except for the siphon, is straight with no bends, which makes this a suitable candidate for this method. This method provides a fully restrained pipe and does not require additional access pits. The following is a typical sequence of construction events: 1. Construction of the insertion and receiving pits. 2. CCTV of host pipe to confirm location of bends or obstructions. 3. Cleaning of host pipe. 4. Assembly of the HDPE pipe using butt fusion into pipe strings to match the spacing of the insertion pits. 5. The pipe is placed on the rollers. 6. The winch or static equipment is placed in the receiving pit. Pipe reducing equipment and pull rods or wire are placed in the insertion pit and attached to the pull head on the HDPE. 7. The pipe is pulled through the host pipe, maintaining constant tension on the pull so the HDPE doesn t revert before the installation is complete. 8. Tension is released and within 2 hours the pipe has reverted to 90 percent of the original size. Typically, HDPE is allowed to fully relax overnight. 9. Connections to restore blow off and air release valves. 10. Liner pipe is pressure tested. The following are some of the advantages of tight fit liner rehabilitation: Minimal cross sectional loss. Long insertion lengths are possible in straight sections. Tightly fits to existing pipeline. Improved C value. Reconnections and taps can be made easily. The following are some of the disadvantages of tight fit rehabilitation: Impacts of placing the pipe in tension may reduce strength. 3 9

34 Require long construction trenches for insertion. Requires skilled labor, limited contractors. Does not navigate bends Cured in Place Pipe (CIPP) Liner (For Pressure Pipelines) The CIPP process is covered by the ASTM F1216 and F2019 standards and can be structural or semi structural. This process utilizes resin transported through a matrix of materials that may consist of needled polyester felt with or without woven glass matting layers. The resin impregnated felt material is inverted into the existing host pipe from access pits or structures using water. The material can be pulled into place based on the specific conditions of the insertion. Once in place air, steam or hot water is used to expand and cure the resin causing a tight fitting bond upon the current internal pipeline wall. The curing process Figure 3 6. Cured in Place Rehabilitation Process can take up to 24 hours depending on the temperature and thickness of the liner. The process produces a seamless pipe within a pipe that is expanded and solidified once inside. The installation would require sufficient access to the pipe to allow for the inversion of the liner material and would need to be reviewed in detail for the design. Other considerations with this alternative are addressing bends in the pipe, any active infiltration or inflow, and sealing the end connection. The ground water level is not expected to be an issue, however, the bend in the pipe may result in wrinkles in the liner. The installation should be inspected with CCTV following installation to determine the extent of any wrinkles. The advantages of CIPP include: Retains majority of the cross sectional area and typically provides a lower C factor resulting in similar flow capacity. Structural, tight fit liner that uses existing pipe wall as the form for the new pipe. Short curing time allows pipe to return to service quickly. The disadvantages of CIPP include: Limited range of pressure and diameter. Requires specialized equipment and certified installers. Requires the pipe to be out of service, cleaned and dry. The use of cured in place pipe is not considered feasible for rehabilitation of the pipeline. The material would result in the loss of a few inches in diameter and does provide improved flow characteristics. The constructability of the liner would be difficult. The weight of the liner for this 3 10

35 diameter would limit the distances that could be lined to less than 1,000 feet and access for the equipment would be difficult. This method would require additional excavation pits and connection fittings be constructed along the alignment Carbon Fiber Reinforced Polymer System (CFRP) A relatively new method for lining large diameter pipe is to use the hand applied CFRP. This method uses a bi directional weave of carbon fibers and an epoxy to form a composite system on the interior of the host pipe. As shown in Figure 3 7, several layers can be built up to form a composite lining of the required thickness to provide structural rehabilitation. The repair provides a system that is specifically designed for the requirements of each project. The structural strengthening system provides restoration of damaged or weakened pipe to meet or exceed original design requirements. The system utilizes layers of CFRP composite which is applied both longitudinally and circumferentially that will bond to the host pipe. The host pipe becomes a Figure 3 7. Cured in Place Rehabilitation Process form for the carbon fiber composite which when cured becomes the new pipe. The application of CFRP requires detailed surface preparation in order to maximize the contact and bond strength between the pipe wall and the CFRP. The pipe has to be cleaned and dry during the installation period and condensation is not acceptable. Dehumidifiers are commonly used to control humidity during the installation. The CFRP provides the following advantages: Minimal impact on the hydraulics with an improved friction loss and a slight loss of diameter (0.25 to 0.75 inches). The system is installed through existing access manways and requires a short curing period before the pipe can be back in service. Corrosion resistance provides long service life. Can be installed in curves. The disadvantages of CFRP are: The pipe must be out of service for surface preparation and curing. The cure time is typically four days. CFRP is installed manually, which increases cost. 3 11

36 The use of CFRP is considered not feasible for rehabilitation of the pipe. This method is typically used for short segments of pipe and is not cost effective for long segments. 3.4 RESULTS OF INITIAL SCREENING The results of the initial screening are presented in Table 3-3, which also identifies the three rehabilitation methods carried forward for a more detailed analysis. Table 3-3. Results of Preliminary Screening OPTION COMMENTS CARRIED FORWARD Cement Mortar Segmented Sliplining with FRP (HOBAS, Flowtite) Continuous Sliplining with HDPE Tight Fit Lines Using HDPE Swagelining CIPP Reduced diameter of rehabilitated pipe, no improvements in flow characteristics, not considered a fully structural liner system, construction issues Corrosion resistant, improved flow factors, shorter access pits Corrosion resistant, improved flow factors, no joints (pipe is fused) Corrosion resistant, improved flow factors, no joints (pipe is fused) Significant constructability issues including equipment access and requirements for additional excavation pits and construction fittings No Yes Yes Yes No Structural Lining with CFRP Typically used for short segments of pipe and not cost effective for long segments No 3-12

37 4.0 Comparative Analysis of Preferred Alternatives 4.1 OVERVIEW As discussed in Section 3.0, three technologies were selected for further development and comparison: segmented sliplining with FRP, continuous sliplining with HDPE, and tight fit liner with HDPE. In addition to the discussion in this section, these methods will be evaluated in the PDR, which will address specific issues such as type and location of access, thickness of material, final hydraulic impacts, and ultimately which method to include in the bid documents. 4.2 EVALUATION APPROACH To objectively assess the value of each alternative, a ranking system was used to score each rehabilitation method. The scoring system is presented in Table 4 1. Table 4 1. Summary of Alternatives Ranking System RANK RECOMMENDATIONS 5 Satisfies project objectives with significant noted advantages. 4 Satisfies project objectives with noted advantages. 3 Satisfies project objectives. 2 Satisfies project objectives with noted disadvantages. 1 Satisfies project objectives with significant noted disadvantages. The evaluation criteria used to compare the alternatives are listed in Table 4 2. In addition to more in depth review of the four criteria used for the preliminary screening described in Section 3.0, the analysis of preferred alternatives included a cost and commercial risk criteria, which involved development of a conceptual cost estimate and net present worth for each rehabilitation method as well as consideration for project risks. Table 4 2. Description of Evaluation Criteria CRITERION Hydraulics Service Life Constructability Potential Environmental and Public Impacts DESCRIPTION Evaluation using current information available on the existing pipe, assuming 25 psi. Friction factors based on engineering judgment and published reports. Estimation of possible impacts on pipe material from corrosion resulting from exposure to possible soil and water contaminants. Abrasion resistance estimated from public information and general deterioration that could impact pipe material. Comparison of accessibility with equipment, modifications to piping such as removing a section of pipe for construction of an access pit with trench box and excavations, and any other factors that could impact the construction schedule, availability of products, or design of the pipeline. Comparison of environment and public factors included in the environmental documentation, traffic impacts, OC Flood Control District coordination, Santa Ana River bike path impacts, etc. 4 1

38 CRITERION Costs Commercial Risk DESCRIPTION Comparison of estimated construction cost (conceptual) and net present worth to implement the proposed method. Comparison of availability of pipe vendors and contractors with proven track record for work of this nature. The basis for scoring was as follows: Hydraulics The scoring for this criterion was dependent upon the alternative s ability to meet the maximum flow capacity from P2 with reduced impacts to pumping (which would also be accounted for in the cost criterion). Generally, a larger internal diameter pipeline with a lower friction factor would receive a higher rating. Service Life The scoring for this criterion was based upon the pipeline material s corrosion and abrasion resistance relative to soil and water corrosivity. Alternatives using a pipe material with greater corrosion and abrasion resistance would receive a higher rating. Constructability The scoring for this criterion was based upon the pipe access pit excavation requirements, ability of the pipe material to be pulled through the host pipe without damage to the liner, and accessibility for construction equipment to build the pipe. Alternatives that had fewer constructability issues would receive a higher rating. Potential Environmental and Public Impacts The scoring for this criterion takes into account impacts to the local residents and traffic, coordination with the Orange County Flood Control District for construction, potential impacts to the bike path, and factors included in the environmental documentation. Alternatives that had fewer impacts would receive a higher rating. Costs The scoring for this criterion accounted for the construction cost of the alternative along with the net present worth. Generally, alternatives with a lower net present worth would receive a higher rating. Commercial Risk The scoring for this criterion accounted for pipe vendor and contractor availability and cost certainty. The paragraphs that follow describe each criterion and assign relative scores to rank each alternative. 4.3 HYDRAULICS As part of the development of the preliminary design for the AWTP expansion, Black & Veatch performed an analysis of the additional secondary effluent (SE) required from OCSD P2 to allow GWRS to operate at its ultimate capacity of 130 mgd. The nominal pipe diameter (inside diameter) of each of the three alternatives will have an effect on the hydraulics of the pipe when operating conditions and flow rates from the SE facilities are considered. An operating pressure of 25 psi was used to evaluate the alternatives. The actual operating pressure will be determined as part of the design of the pump station. For the purposes of comparison of the rehabilitation alternatives we 4 2

39 used the elevation difference of approximately 30 feet and added 25 feet of headloss through the pipe and pump station. The friction factors used were based on engineering judgment and published reports. For purposes of comparison, the following pipeline diameters were evaluated as shown in Table 4 3 below. Each alternative is capable of meeting the maximum flow capacity of 80 mgd from P2. Details for the hydraulic analysis are provided in the following paragraphs. Alternatives that provided the highest flowrate, lowest friction factor, and largest diameter were given a higher scoring rating. Table 4 3. Description of Evaluation Criteria ALTERNATIVE NOMINAL INTERNAL PIPE DIAMETER (INCH) RESULTANT OUTSIDE DIAMETER (INCH) ANNULAR SPACE (INCH) CAPACITY (MGD) VELOCITY (FT/S) No. 1 Segmented Sliplining with FRP (1) No. 2 Continuous Sliplining with HDPE No. 3 Tight fit Liner with HDPE Note: (1) FRP dimensions shown are based on FlowTite pipe Segmented Sliplining with FRP The segmented sliplining with FRP (FlowTite ) pipe would have an OD of 61.6 inches. This OD provides the preferred minimum annular space of 2 inches required for ease of installation. FlowTite information is shown rather than HOBAS as the equivalent pipe size for HOBAS has an external diameter of 63 inches. Using the 25 psi as the headloss in the pipe and a C factor of 120, the capacity of the pipe would be approximately 110 mgd, which exceeds the required maximum flow of 80 mgd. Equation 4 1. Flow Calculation for Segmented Sliplining Pipe 4 3

40 4.3.2 Continuous Sliplining with HDPE The continuous sliplining with HDPE would have an OD of 63 inches (provided by United Pipe Group) and a DR of 26. This OD provides less than the minimum annual space of 2 inches typically used, which would increase the risk of pipe damage or the pipe getting stuck during installation. Using the 25 psi as the headloss in the pipe and a C factor of 120 the capacity of the pipe with HDPE sliplining would be approximately 102 mgd, which exceeds the required maximum flow of 80 mgd. Equation 4 2. Flow Calculation for Continuous Sliplining with HDPE Tight Fit Liner with HDPE The tight fit liner with HDPE would have an OD of 66 inches (provided by Murphy Pipelines) and a DR of 26. This pipe is designed to fit snug against the host pipe so there is no grouting of the annular space. Using the 25 psi as the headloss in the pipe and a C factor of 120 the capacity of the pipe with tightfit liner with HDPE would be approximately 117 mgd, which exceeds the required maximum flow of 80 mgd. Equation 4 3. Flow Calculation for Tightfit Liner with HDPE 4.4 SERVICE LIFE The structural service life is an estimation of the possible impacts on the pipe material from corrosion resulting from exposure to possible contaminants in the soil and water and potential for joint failure. The abrasion resistance is estimated from published information and general deterioration factors that could impact the pipe material. 4 4

41 4.4.1 Segmented Sliplining with FRP The structural service life of FRP pipe is published to be 100 years since the material is corrosion resistant and has good material properties for resisting abrasion. In some installations, the pipe has discolored over time, but no loss in physical strength has been determined. The number of pipe joints could introduce a potential for failure at the pipe joints Continuous Sliplining with HDPE The structural service life of HDPE pipe is published to be 100 years since the material is corrosion resistant and has good material properties for resisting abrasion. The pipe is continuous and joined by butt fusion so failure at a joint is extremely unlikely even during a seismic event. The pipe has been reported to have increased brittle factures from exposure to chlorine or oxidants. However, the infrequent maintenance injection of chlorine currently being considered for the P2 SE facilities is not considered to be a cause for concern should HDPE pipe be selected Tight Fit Liner with HDPE Similar to continuous sliplining, the structural service life of HDPE pipe is published to be 100 years since the material is corrosion resistant and has good material properties for resisting abrasion. The pipe has been reported to have increased brittle factures from exposure to chlorine or oxidants However, the infrequent maintenance injection of chlorine currently being considered for the P2 SE facilities is not considered to be a cause for concern should HDPE pipe be selected. 4.5 CONSTRUCTABILITY Constructability addresses accessibility with equipment, modifications to the piping, such as removing a section of pipe or construction of an access pit with a trench box. This criterion also includes factors that impact the construction schedule, or design of the pipeline. The alignment of the 66 inch pipeline is closely bounded by other significant OCSD pipelines within the utility corridor parallel to the Santa Ana River. Heading north from P2, the 66 inch pipeline is located between the existing 120 inch and 84 inch OCSD pipelines. Approximately 250 feet north of Adams Avenue, the 66 inch pipe siphons beneath the 120 inch pipeline and is located to the west of the 120 inch until termination at the effluent junction box south of Garfield Avenue. Consideration of the proximity to these pipelines and other utilities is necessary when considering trenching and shoring for access pits. Figure 4 1 shows a representative cross section at for each of the two alignment scenarios for the 66 inch pipeline. 4 5

42 Figure 4 1. Representative Cross Sections for the 66 inch Pipeline Alignment Although the access pits would vary in length, all three options require a similar width of about 20 feet, excavation and similar equipment and given the proximity of the parallel pipes, have similar constructability issues. The main differentiator is the annular gap and the risk of the pipe becoming stuck during installation. All three options would require similar construction activity to line through the siphon, which although a significant amount of work, is not considered a differentiator between the options Segmented Sliplining with FRP The constructability of FRP requires shorter access pits, about 30 feet long, and based on the information provided by FlowTite pipe the distance for each reach would be 2,000 feet. The joint length would be 20 feet or shorter to meet the existing conditions. The design of the flush joint by HOBAS would require modification to the sleeve to increase the thickness to provide 45 psi capability to address potential surge pressures. The FlowTite pipe is designed for pressure and would use the standard flush joint shown in Figure 4 2. Based on FlowTite pipe, the annular gap is 2.2 inches, which is adequate. 4 6

43 Figure 4 2. Flush Joint for FRP Continuous Sliplining with HDPE The constructability of continuous sliplining would require excavation of access pits that will be approximately 60 feet long. This would also require the setup of the fusion machine and a string of pipe the length of the pull, which is estimated to be 2,000 to 3,000 feet. However, if access manways are required to be replaced every 2,000 feet, then the additional length would not be needed. The construction schedule would be shorter than segmented sliplining. The annular gap is 1.5 inches Tight Fit Liner with HDPE The constructability of tight fit sliplining is similar to that of continuous sliplining; however, the construction schedule would likely be a little shorter. This is the result of improved constructability since the annular space does not require grouting. 4.6 ENVIRONMENTAL AND PUBLIC IMPACTS Potential impacts to the environment and public will include factors included in the environmental documentation, traffic impacts, impacts to the Santa Ana River bike path or other factors Segmented Sliplining with FRP The impacts to the environment would be mitigated by the shorter access pits and the existing easement would be minimally impacted. The pipe could be stored off site and transported to the excavation as needed for construction or stored along the easement. However, given that the construction period would be longer than the other alternatives, the length of any potential impact is marginally longer Continuous Sliplining with HDPE The impacts to the environment would be affected by the access pits and the existing easement would be minimally impacted except in the areas of construction. The pipe would be stored and assembled along the easement but arranged in such a manner so as not to impact the bike path or traffic Tight Fit Liner with HDPE The impacts to the environment would be affected by the access pits and the existing easement would be minimally impacted except in the areas of construction. The pipe would be stored and assembled along the easement but arranged in such a manner so as not to impact the bike path or traffic. 4 7

44 4.7 COST An additional criterion used to evaluate the three alternatives is cost. Both estimated construction cost and net present worth were considered. Alternatives with lower net present worth values were given a higher score Construction Cost The Association for the Advancement of Cost Engineering (AACE) International defines five class estimates, in AACE International Recommended Practice No. 17R 97, which are typically used for planning purposes. A Class 5 Estimate is the rough order of magnitude estimate, usually used to evaluate project alternatives, and is the class of estimate supported by this conceptual level cost estimate for the EM. Standard unit prices were developed for the primary components in each alternative. Scope items were parametrically estimated utilizing cost data from similar projects in scope and size and adjusted to suit the specific requirements of this project. The estimated construction costs presented herein are considered to be conceptual and include a 35 percent contingency factor. Construction costs were estimated based on current (2018) pricing. The cost comparison is presented is Table 4 4 which shows the base estimate together with the expected accuracy range based on a Class 5 estimate. Table 4 4. Construction Cost Comparison CONSTRUCTION COST (CONCEPTUAL ESTIMATE) ALTERNATIVE BASE ESTIMATE LOW ( 20%) HIGH (+30%) No. 1 Segmented Sliplining with FRP $24.9 M $19.9 M $32.4 M No. 2 Continuous Sliplining with HDPE $18.1 M $14.5 M $23.5 M No. 3 Tight Fit Liner with HDPE $23.5 M $18.8 M $30.5 M Note: 1. The contingencies, escalation factors, and ranges described above are included to reflect the conditions of this Project. Actual costs for the Project may be affected by a number of factors, such as the future market conditions, relative stability of material costs, contractor's means and methods Net Present Worth The net present worth is an important consideration that takes into account operational costs for pumping over the lifetime of the pipeline. Annual power costs were calculated for the three different pipeline materials/diameters evaluated. The following assumptions were made: Cost of electricity $0.11/kWh Pump efficiency of 80 percent Pumping 24 hours/day Pipe length of 15,750 LF 4 8

45 Table 4 5. Present Worth Calculations Input PRESENT WORTH ENERGY COST CALCULATION Flow VALUE 60 mgd Interest/Discount Rate 6% Inflation/Escalation Rate 3.5% Time 30 years Energy Cost Alt No. 1 Segmented Sliplining with FRP (61.6 OD) $314,700 Alt No. 2 Continuous Sliplining with HDPE (63 OD) $339,500 Alt No. 3 Tight Fit Liner with HDPE (66 OD) $299,400 The estimate annual operating costs are shown on Figure 4 3. The P2 SE facilities are currently planned to operate at 60 mgd (average) with a minimum flowrate of 30 mgd and an approximate maximum flowrate of 80 mgd. Figure 4 3. Comparison of Annual Power Costs 4 9

46 Table 4 6. Net Present Worth for Energy Cost of Pumping for Each Alternative ALTERNATIVE No. 1 Segmented Sliplining with FRP (61.6 OD) No. 2 Continuous Sliplining with HDPE (63 OD) No. 3 Tight Fit Liner with HDPE (66 OD) NPW VALUE $6.6 M $7.2 M $6.3 M The total net present worth of each of the three alternatives is shown on Table 4 7 below: Table 4 7. Net Present Worth of Each Alternative NET PRESENT VALUE ALTERNATIVE CAPITAL ENERGY TOTAL No. 1 Segmented Sliplining with FRP (61.6 OD) $24.9 M $6.6 M $31.5 M No. 2 Continuous Sliplining with HDPE (63 OD) $18.1 M $7.2 M $23.5 M No. 3 Tight Fit Liner with HDPE (66 OD) $23.5 M $6.3 M $29.8 M 4.8 COMMERCIAL RISK The final criterion used to evaluate the alternatives takes into account pipe vendor and contractor availability and cost certainty Segmented Sliplining with FRP An adequate pool of experienced contractors exist that have the capacity of installing segmented FRP pipe. There are two pipe vendors with suitable pipe product, thereby ensuring a competitive bid Continuous Sliplining with HDPE An adequate pool of experienced contractors exist that have the capacity of installing HDPE pipe and several pipe vendors able to manufacture up to 63 inch HDPE pipe. Being a petroleum based product, any volatility in the cost of crude oil impacts the raw cost of the HDPE material Tight Fit Liner with HDPE Currently there is only one HDPE pipe vendor in North America with the ability to manufacture HDPE pipe greater than 63 inches (outside diameter). In addition, the number of contractors with the experience and necessary equipment to tight fit a 66 inch pipe is limited to 2 or 3 at most. This introduces significant commercial risk. In addition, being a petroleum based product, any volatility in the cost of crude oil impacts the raw cost of the HDPE material. 4.9 SUMMARY OF ALTERNATIVES Preparation of this EM began with identifying the universe of alternatives for rehabilitating the 66 inch pipeline. Of the nine methods identified in Section 3.0, three were determined to not be 4 10

47 appropriate for the scope of this project. The remaining six alternatives were screened against evaluation criteria to ultimately identify the three alternatives carried forward to Section 4. The three alternatives were carried forward and evaluated against the six criteria: hydraulics, service life, constructability, environmental and public, cost and commercial risk. The results of the evaluation are summarized in Table 4 8. The table also presents the total ranking for each criterion. Table 4 8. Comparison of Alternatives ALTERNATIVE HYDRAULICS SERVICE LIFE CONSTRUCTABILITY ENVIRONMENTAL & PUBLIC No. 1 Segmented Sliplining with FRP No. 2 Continuous Sliplining with HDPE No. 3 Tight Fit Lining with HDPE COST COMMERCIAL RISK TOTAL 4 11

48 5.0 Recommendations Based on the evaluation, the following approach is recommended: 1. The evaluation shows that there is little to differentiate between segmented sliplining with FRP and continuous sliplining with HDPE. Both are technically feasible options which satisfy each project objective and evaluation criteria. We recommend that the design be developed and the pipeline rehabilitation bid using both options and allowing market forces to drive the final selection. This would ensure the most competitive bid while still satisfying the project requirements. 2. The reduction in energy costs for utilizing a tight fit liner does not compensate for the increased construction cost. In addition, this alternative has a substantial potential commercial risk. For these reasons, this option is not recommended. 5 1

49 Appendix A Summary of 2012 CCTV Inspection

50 Table A 1. Summary of Results of 2012 CCTV Inspection MH IPB0005 (STATION ) TO MH IPB0000 (OOBS) Distance (ft.) Notes 0 Water level about 10%; surface aggregate visible, more at crown 79, 112 Stain at Joint, water level 30% 90 Water level 60% 245 Reinforcement projecting through surface 291 Appears joint repair failed, material change to liner 458 Water level 40%, joint covered 562 Water level 30%, some deposits on sides, the crown is clean 582 Material change? Possible drip at joint 688 Joint has a seal, part of liner 1150 Joint has a seal, part of liner 1395 Crawler stuck, moving slowly in deposits 1525 Deposits on sides of pipe 1654 See curve to Ocean Outfall Booster Station (OOBS) 1667 End MH IPB0015 (Station ) to MH IPB0010 (Station ) Distance (ft.) Notes 7 Surface aggregate exposed, water level about 10% Deposits settled across the invert 87, 101 Reinforcing exposed at crown 94 Deposits settled Reinforcing exposed, some appears longitudinal Deposits settled 368 Water level 20% 380 Deposits Reinforcing exposed, bad near Deposits 603 Crawler stuck in deposits, moving slowly Reinforcing exposed, deteriorated crown Crawler stuck in deposits 780 Water level 25% 985 Ended (tether?) Gap not CCTV 1,015 feet MH IPB0020 (Station ) to MH IPB0015 (Station ) Distance Notes 0 Water level 15%, surface aggregate exposed nearly continuous, above spring line and crown Deposits settled in invert

51 Deposits and aggregate exposed Continuous deposits varying amounts 458 Particles appear moving fast towards crawler noted in water Crawler moving slowly through deposits 550 Water level 25% 581 Abandoned survey Reverse Direction 0 Surface aggregate visible 62 Deposits settled in invert 165 Rust showing through mortar Deposits settled Deposits settled crawler moving slowly through Deposits settled crawler moves slowly through 1001 Black stain at joint 1168, 1327 Joint gap?? 1361 Tracks from other direction inspection MH IPB0025 (Station ) to MH IPB0020 (Station ) Distance Notes 6 Surface aggregate exposed above springline and on crown 571 Water level 15% Deposit settled from 5 o clock to 6 o clock position, crawler stirred up deposits, moving slowly, wheel slipping 904 Deposit observed below water level Deposit settled across invert, crawler struggled to get through 1496 Water level 10% Joint deflections? Crawler slipping, deposit observed below water level 1800 Large amount of deposits settled and compacted 1811 Crawler stuck, abandoned survey No reverse Gap of 189 feet MH IPB 0030 (Station 90+00) to MH IPB0025 (Station ) Distance (ft.) Notes 22 Deposits settled; aggregate exposed does not appear as bad 26 Joint deflection? 122 Deposits settled and debris Surface aggregate exposed above springline and on crown Deposits settled Deposits settled, surface aggregate continuous 1097 Sand observed in invert below water (Is there a hole in the pipe) 1340 Rust from reinforcement

52 1420, 1500 Deposits settled Deposits settled crawler struggled to get through (15 minutes) 1721 Shadow of something at 3 o clock 1818 Joint deflection? 1901 Different color 1942 Dark stain on wall Abandoned survey (cable?) did not see manhole MH IPB 0030 (Station 90+00) to South Siphon Distance Notes 0 Plastic or PVC liner, water level 0% tap with liner 24 End of liner at joint, change material to RCP Continuous Surface aggregate exposed, more pronounced at the crown 53 Tracks in sediment Some deposits settled, big pieces of debris (manned entry to remove) 99 Crawler slipping Joint shadows, deposits settled 303 Deposits settled intermittently, below water level 390 Crawler stuck Abandon survey Gap of 1,010 feet MH IPB0035 (Station 70+00) to Siphon North Distance (ft.) Notes 0 Water level 0%, surface aggregate exposed from 9 o clock to 3 o clock position 274 Material change to liner from RCP 284, 300 Tap lined 310 Liner, abandoned survey Siphon South to Siphon North Distance (ft.) Notes 186 Damaged liner MH IPB 0040 (Station 50+00) to MH IPB0035 (Station 70+00) Distance Notes 0 Water level 0% 0 Surface aggregate exposed 9 o clock to 3 o clock 427 Joint defection? Change in color on wall 528 Some deposit settled 727 Joint deflection?? water level changed to 5% 1997 Manhole MH IPB0045 (Station 30+00) to MH IPB0040 (Station 50+00) Distance Notes 0 Surface aggregate exposed, water level 5%

53 6, 540, 1482 Deposits settled Crown corrosion exposed reinforcing 965, 1385, 1609 Material in joint, deposits 1987 Manhole

54 IPB 0005 to OOBS MH (0000) Summary of Video Map length 1604 feet MH IPB0005 (Station ) to MH IPB0000 (OOBS) Distance (ft) Notes 0 Water level about 10%; surface aggregate visible, more at crown 79, 112 Stain at Joint, water level 30% 90 Water level 60% 245 Reinforcement projecting through surface 291 Appears joint repair failed, material change to liner 458 Water level 40%, joint covered 562 Water level 30%, some deposits on sides, the crown is clean 582 Material change? Possible drip at joint 688 Joint has a seal, part of liner 1150 Joint has a seal, part of liner 1395 Crawler stuck, moving slowly in deposits 1525 Deposits on sides of pipe 1654 See curve to OOBS 1667 End Water level appears more than 50% can t see most of the pipe to know if there are defects. Exposed aggregate at crown has been continuous.

55 Surface reinforcement projecting can impact rehabilitation Something hanging down, possible joint repair attempt. Pipe material change?

56 Joint appears to be sealed or part of a liner Curve to BS in distance, joints are sealed, part of liner.

57 IPB0015 to IPB0010 Summary of Video Map length 2,000 feet MH IPB0015 (Station ) to MH IPB0010 (Station ) Distance Notes 7 Surface aggregate exposed, water level about 10% Deposits settled across the invert 87, 101 Reinforcing exposed at crown 94 Deposits settled Reinforcing exposed, some appears longitudinal Deposits settled 368 Water level 20% 380 Deposits Reinforcing exposed, bad near Deposits 603 Crawler stuck in deposits, moving slowly Reinforcing exposed, deteriorated Crawler stuck in deposits 780 Water level 25% 985 Ended (tether?) Gap not CCTV 1,015 feet deterioration in crown of pipe Reinforcement exposed by

58 Deposits and aggregate exposed in crown Rebar exposed along crown, deterioration

59 MH IPB0020 to IPB0015 Map distance 2,000 feet; upstream 581; downstream 1,361 total 1942 feet. Saw tracks from first. MH IPB0020 (Station ) to MH IPB0015 (Station ) Distance Notes 0 Water level 15%, surface aggregate exposed nearly continuous, above spring line and crown Deposits settled in invert Deposits and aggregate exposed Continuous deposits varying amounts 458 Particles appear moving fast towards crawler noted in water Crawler moving slowly through deposits 550 Water level 25% 581 Abandoned survey Reverse Direction 0 Surface aggregate visible 62 Deposits settled in invert 165 Rust showing through mortar Deposits settled Deposits settled crawler moving slowly through Deposits settled crawler moves slowly through 1001 Black stain at joint 1168, 1327 Joint gap?? 1361 Tracks from other direction inspection

60 settled and aggregate exposed above spring line and on crown. Water level 15%. Deposit discoloration in Joint. Observed black

61 Water level increase, continuous aggregate exposed, moving slowly in deposits. Reverse direction Joint shadow

62 deposits settled Large amount of deposits settled Large amount of

63 OCWD GWRS IPB0025 to IPB0020 Summary of Video; Map length 2,000 feet MH IPB0025 (Station ) to MH IPB0020 (Station ) Distance Notes 6 Surface aggregate exposed above springline and on crown 571 Water level 15% Deposit settled from 5 o clock to 6 o clock position, crawler stirred up deposits, moving slowly, wheel slipping 904 Deposit observed below water level Deposit settled across invert, crawler struggled to get through 1496 Water level 10% Joint deflections? Crawler slipping, deposit observed below water level 1800 Large amount of deposits settled and compacted 1811 Crawler stuck, abandoned survey No reverse Gap of 189 feet Observed aggregate exposed on pipe from 9 o clock to 3 o clock. Crown corrosion is predominant in some sections.

64 Deposits settled in invert, robot slipped but was able to plow through. Deposits settled to about 900 ft. Close up of deposits settled Possible joint deflection from 1587 to 1611 feet, could not tell for sure in video.

65 some below water until about 1368 ft. Deposit settled and compacted, Close up of deposit material

66 to about 1811 ft. Robot could not pass. Deposits settled and compacted Survey abandoned, close up of debris.

67 MH IPB0030 (south of Adams) to IPB0025 Map distance 2,000 feet Gap 60 MH IPB 0030 (Station 90+00) to MH IPB0025 (Station ) Distance (ft.) Notes 22 Deposits settled; aggregate exposed does not appear as bad 26 Joint deflection? 122 Deposits settled and debris Surface aggregate exposed above springline and on crown Deposits settled Deposits settled, surface aggregate continuous 1097 Sand observed in invert below water (Is there a hole in the pipe) 1340 Rust from reinforcement 1420, 1500 Deposits settled Deposits settled crawler struggled to get through (15 minutes) 1721 Shadow of something at 3 o clock 1818 Joint deflection? 1901 Different color 1942 Dark stain on wall Abandoned survey (cable?) did not see manhole aggregate not as deteriorated. Joint deflection? Deposits settled,

68 amount of debris and deposits Large exposed on sides and crown. Surface aggregate

69 Deposits settled Appears to be sand in the invert.

70 Rust stain on crown, reinforcement exposed. Shadow at 3 o clock

71 Joint deflection??

72 IPB0030 (Dome S/Adams) to South Siphon Map length 1,400 feet; gap of 1,010 feet MH IPB 0030 (Station 90+00) to South Siphon Distance Notes 0 Plastic or PVC liner, water level 0% tap with liner 24 End of liner at joint, change material to RCP Continuous Surface aggregate exposed, more pronounced at the crown 53 Tracks in sediment Some deposits settled, big pieces of debris (manned entry to remove) 99 Crawler slipping Joint shadows, deposits settled 303 Deposits settled intermittently, below water level 390 Crawler stuck Abandon survey Gap of 1,010 feet is lined with what appears to be PVC, note tap at 11 o clock has liner Note pipe

73 End of liner begin RCP Transition joint

74 Deposits settled Deposits settled Similar to 99 feet (deposit removed by manned entry), aggregate exposed in crown, crawler able to pass through. be aligned, ovality not obvious if a concern. Joints not inspected, appear to

75 at 300 feet intermittent to end of survey Deposits settled begin Survey Abandoned at 390 FT Gap of 1,010

76 IPB0035 to Siphon N Map length from IPB0035 to Siphon N 400 feet. MH IPB0035 (Station 70+00) to Siphon North Distance Notes 0 Water level 0%, surface aggregate exposed from 9 o clock to 3 o clock position 186 Damaged liner 274 Material change to liner from RCP 284, 300 Tap lined 310 Liner, abandoned survey Surface aggregate exposed, entire segment similar. Transition from RCP to Liner

77 Siphon North to Siphon South Map length 200 feet 186 Damaged liner In the siphon Coming up out of siphon: Damaged liner at 186 feet

78 IPB0040 to IPB0035 Map length 2,000 feet MH IPB 0040 (Station 50+00) to MH IPB0035 (Station 70+00) Distance Notes 0 Water level 0% 0 Surface aggregate exposed 9 o clock to 3 o clock 427 Joint defection? Change in color on wall 528 Some deposit settled 727 Joint deflection?? water level changed to 5% 1997 Manhole Surface aggregate exposed, joint appears to be in good condition. Joint shadow, change in color

79 Some sediment in pipe invert Surface aggregate exposed typical of entire segment. Joint appears to have some deflection possible. water level 5% Manhole,

80 IPB0045 to IPB0040 Map length 2,000 feet Distance Notes 0 Surface aggregate exposed, water level 5% 6, 540, 1482 Deposits settled Crown corrosion exposed reinforcing 965, 1385, Material in joint, deposits Manhole Deposit settled Crown corrosion exposed reinforcing. Water level 5%, no joint deflection, at 965 material in joint.