Full Text
April 2016 - FINAL DRAFT 8-1 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx Chapter 8 CONDITION ASSESSMENT AND REHABILITATION AND RELIABILITY IMPROVEMENTS This chapter summarizes the results from the City of Modesto’s (City's) collection system condition assessment program and presents the recommended rehabilitation and reliability improvements based on the condition assessment results. 8.1 BACKGROUND Portions of the City's wastewater collection system are more than 100 years old and present a number of issues related to deterioration. Much of the large diameter trunks are constructed of unlined reinforced concrete pipes (RCP) that are susceptible to corrosion from naturally occurring gases in the sewer. In the past, the City completed condition assessments to identify collection system infrastructure that should be rehabilitated or inspected in the future. Specifically, the City conducted a condition assessment of the City's large diameter trunks in 2005, the results of which are documented in the previous CSMP. The City has also completed additional condition assessment studies in 2009 and 2014. However, none of these studies assessed all of the large diameter, unlined RCP. To assess the condition of these large diameter, unlined RCP, the City contracted with Brown and Caldwell (BC) to conduct a condition assessment of approximately 25,000 linear feet (LF) of unlined sewers 16 inches in diameter and larger. BC also conducted a condition assessment of 209 manholes, the Shackelford siphon, the inlet and outlet structures of the remaining siphons, and the Woodland Lift Station (LS). 8.2 RECOMMENDED IMPROVEMENTS BC’s investigation provides recommendations for repair and rehabilitation. A ten-year rehabilitation and replacement capital improvement program (CIP) was also developed that included a schedule for implementing all recommended projects within the next ten years. Figure 8.1 illustrates the general location of the proposed rehabilitation projects, and Table 8.1 provides detailed information for each improvement project. For more information, see Appendix G for BC's Wastewater Collection System Condition Assessment Report. Manhole improvements have not been identified as individual projects and have instead been grouped with pipeline improvements. ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-2 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx In addition to the rehabilitation projects identified in BC’s Condition Assessment Report, this section includes additional projects planned under previous efforts but not yet completed. These projects were part of the City’s CIP and a Preliminary Design Report (PDR), which included a condition assessment of the River Trunk, Sutter Trunk, and CSL facilities during the fall of 2014. Figure 8.2 illustrates the general locations of these projects, and Table 8.2 provides detailed information for each one. 8.2.1 Rehabilitation Projects 8.2.1.1 Area 3 • 24” Rehabilitation along Sutter Trunk (Project RT-9): This project is carried over from the PDR. Based on the results of the condition assessment, a portion of the lower Sutter Trunk shows signs of heavy corrosion, with limited pipeline life remaining. Thus, this segment of pipeline will require rehabilitation. The recommended approach is cured-in-place pipe lining. Since much of the pipeline's interior is inaccessible for a condition assessment, it was assumed that half of the length of the pipeline would be lined. This project is directly upstream of Project A-2. • 48” River Trunk Rehabilitation (Project RT-10): This project is carried over from the PDR. The condition assessment on the River Trunk concluded that excessive corrosion is present in the entire reach of the Trunk from Beard Brook to the Sutter Plant. Isolated segments that have recently failed or are near failure were also observed. Furthermore, a segment of the River trunk in the Gallo Property recently failed and created a sinkhole. Another segment is severely corroded, with exposed concrete reinforcement bars that possibly indicate another failure. Rehabilitation is recommended within the next five years. 8.2.1.2 Area 5 • Santa Rosa Tributary Trunk (Project SR-6): This project is carried over from the 2007 Master Plan and the City’s CIPP (Project SR-6). Project SR-6 involves rehabilitating 1,000 feet of 18-inch diameter RCP. The project is located in Miller Avenue, between Conejo Avenue and Phoenix Avenue. This reach is over 50 years old and has significant deterioration. 8.2.1.3 Area 8 • Ceres Trunk (Project CT-1): This project is carried over from the 2007 Master Plan and the City’s CIPP (Project C-1). Project CT-1 consists of rehabilitating 2,900 feet of 18-, 21-, and 24-inch diameter RCP. This project will rehabilitate the oldest and most deteriorated segment of the Ceres Trunk. It is located between Highway 99 and the Shakelford crossing of the Tuolumne River. ---PAGE BREAK--- R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LSR7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS KIERNAN AVE COVERT RD BACON RD BECKWITH RD NORTH AVE WOODLAND AVE MAZE BLVD CALIFORNIA AVE PARADISE RD WHITMORE AVE SHOEMAKE AVE BLUE GUM AVE KANSAS AVE STODDARD RD AMERICAN AVE TULLY RD MC HENRY AVE COFFEE RD OAKDALE RD ROSELLE AVE CLAUS RD LANGWORTH RD CARVER RD DALE RD PRESCOTT RD FINNEY RD ALBERS RD C-1 D-2 B-2 C-1 A-1 A-1 B-1 C-3 D-1 A-3 HWY 99 HWY 99 ?Î BROWN AND CALDWELL RECOMMENDED REHABILITATION IMPROVEMENTS FIGURE 8.1 CITY OF MODESTO WASTEWATER COLLECTION SYSTEM MASTER PLAN Legend Structural Rehabilitation R7 LS Lift Station Sewer Main Tributary Areas Area 1 Area 2 Area 3 Area 4 Area 5 Area 6 Area 7 Area 8/Northern Ceres Area 9 Area 10 O 0 4,000 8,000 Feet Beard Industrial Park Empire North Ceres C-1 A-2 C-1 Detail B Detail B pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Data/MXDs/Fig 8_1.mxd C-2/S-4B Highway 99 Detail A Detail A ---PAGE BREAK--- ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-4 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx Table 8.1 Summary of Rehabilitation Improvements from BC's Condition Assessment Report Wastewater Collection System Master Plan City of Modesto, California Project Number Project Description/Street Purpose Improvement Category Ex. Size/ Diam. (in) Replace/ New Length (ft) Area 1 West Trunk A-3 Gravity Pipeline Roseburg/Haney Avenue Inspections along this reach indicate that roots have penetrated the RCP. This Pipeline is recommended for urgent repair. The method of rehabilitation will involve cured-in-place pipe (CIPP) lining. Rehabilitation 18 CIPP 3,000 C-1 Gravity Pipeline Woodland Avenue Pipeline aggregate along this reach is either missing or protruding. The method of rehabilitation will involves slip-lining. Rehabilitation 54/60 Slip-lining 24,900 Area 2 Emerald Trunk Tributary B-2 Gravity Pipeline Mercy Avenue Inspections along this reach have observed visible reinforcement in areas of projecting rebar. The method of rehabilitation will involve CIPP lining and slip-lining. Rehabilitation 18/27/54 CIPP/Slip-lining 7,500 D-2 Gravity Pipeline Briggsmore Ave/Tully Rd The pipeline coating has deteriorated and is susceptible to corrosion. Rehabilitation 30 CIPP 110 Area 3 Sutter and South Trunk A-2 Gravity Pipeline Pipelines entering Sutter Plant Pipeline reinforcements within the Sutter reach are corroded, and segments of the wall are missing. PoleCam data on the South Trunk identified pipelines with moderate to severe conditions. The South Trunk Siphon was included in this project for budgeting purposes. Rehabilitation 24/30 CIPP 2,200 C-2/S-4b(1) Gravity Pipeline Beneath Highway 99 This segment is flagged for rehabilitation because it is located beneath Highway 99 and has a high consequence of failure. The method of rehabilitation will involve CIPP lining. Rehabilitation 16 CIPP 400 Area 4 Downtown Tributary C-3 Gravity Pipeline 9th Street Inspections along this reach have exposed missing aggregate, visible reinforcement, and deterioration of the concrete walls. The method of rehabilitation will involve CIPP lining. Rehabilitation 27 CIPP 3,300 D-1 Gravity Pipeline 12th St./Morton Blvd Aggregate and missing segments of the interior wall were observed below the flow line, which indicates that corrosion is due to chemicals in the wastewater. The method of rehabilitation will involve CIPP lining. Rehabilitation 21/24/27 CIPP 1,800 Area 5 Rose Celeste/Santa Rosa Trunk A-1(2) Gravity/Force Main Scenic Dr/Oregon Dr The project includes rehabilitation gravity pipelines and the 14-inch diameter force main extending from the Thousand Oaks Lift Station. Pipeline conditions range from moderate to severe. Urgent repairs are recommended where a void and corroded reinforcements have been observed. The method of rehabilitation will involve CIPP lining. Rehabilitation 16/18/24/30 CIPP 8,800 Area 9 Crows Landing Trunk B-1 Gravity Pipeline Spokane St/Cascade Ave Inspections along this reach have observed missing aggregate and visible reinforcement. The method of rehabilitation will involve CIPP lining. Rehabilitation 30 CIPP 5,600 Notes: This rehabilitation project will incorporate the 2007 Master Plan’s project S-4b, which is currently in the City’s CIP. S-4b recommended rehabilitating 400 feet of 16-inch diameter pipeline under Highway 99. This rehabilitation project will incorporate the 2007 Master Plan’s project SR-1, which is currently in the City’s CIP. SR-1 recommended the rehabilitating 1,700 feet of 24-inch and 30-inch diameter pipeline at the southernmost end of the Santa Rosa Trunk. ---PAGE BREAK--- ---PAGE BREAK--- R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LSR7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS R7 LS KIERNAN AVE COVERT RD BACON RD BECKWITH RD NORTH AVE WOODLAND AVE MAZE BLVD CALIFORNIA AVE PARADISE RD WHITMORE AVE SHOEMAKE AVE BLUE GUM AVE KANSAS AVE STODDARD RD AMERICAN AVE TULLY RD MC HENRY AVE COFFEE RD OAKDALE RD ROSELLE AVE CLAUS RD LANGWORTH RD CARVER RD DALE RD PRESCOTT RD FINNEY RD ALBERS RD RT-9 S-6 CT-1 RT-10 HWY 99 HWY 99 ?Î RT-12 CSMP RECOMMENDED REHABILITATION AND RELIABILITY IMPROVEMENTS FIGURE 8.2 CITY OF MODESTO WASTEWATER COLLECTION SYSTEM MASTER PLAN Legend Structural Rehabilitation Reliability CSL Diversion Structure R7 LS Lift Station Sewer Main Tributary Areas Area 1 Area 2 Area 3 Area 4 Area 5 Area 6 Area 7 Area 8/Northern Ceres Area 9 Area 10 O 0 4,000 8,000 Feet Beard Industrial Park Empire North Ceres C-2/S4-B S4-A Highway 99 Detail A Detail A C-2B CT-1 C-2A Highway 99 Detail B Detail B RT-10 CSL Diversion Structure RT-12 Detail C Detail C pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Data/MXDs/Fig 8_1.mxd ---PAGE BREAK--- ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-6 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx Table 8.2 Summary of Rehabilitation Improvements Wastewater Collection System Master Plan City of Modesto, California Project Number Project Description/Street Purpose Improvement Category Ex. Size/ Diam. (in) New Size/Diam. (in) Replace/ New Length (ft) Area 3 Sutter and South Trunk S-4a Gravity Pipeline(1) Beneath Highway 99 This improvement will increase reliability by constructing a parallel 16-inch diameter trunk under Highway 99. Reliability - 16 - 400 River Trunk RT-9 Gravity Pipeline(2) Sutter Avenue Based on the results of the condition assessment, lower segments of the Sutter Trunk will require rehabilitation. Rehabilitation 24 - CIPP 1,300 RT-10 Gravity Pipeline(2) Along Tuolumne River Based on results of the condition assessment, segments of the River Trunk will require rehabilitation. Rehabilitation 48/60/66 - CIPP 15,000 RT-11 River Bank Armament(2) Along Tuolumne River This involves armoring the riverbank to prevent future erosion and exposure of the CSL and River Trunk. Reliability - - New - RT-12 CSL Diversion Structure(2) Along Tuolumne River A contingency will divert flows between the CSL and River Trunk. Reliability - - New - Area 5 Rose Celeste/Santa Rosa Trunk SR-6 Gravity Pipeline Kimble Street and Floto Street This reach is over 50 years old and has significant deterioration to the point of compromising the pipe's structural integrity. Rehabilitation 18 - Rehab 1,000 Area 8 Ceres Trunk CT-1 Gravity Pipeline(1) Parallel to Tuolumne River This project rehabilitates the oldest and most deteriorated segment of the Ceres Trunk. Rehabilitation 18/21/24 CIPP 2,900 C-2a Gravity Pipeline(1) Highway 99 crossing This improvement will increase reliability by constructing a parallel 24-inch diameter trunk under Highway 99. Reliability 24 - New 300 C-2b Gravity Pipeline(1) Highway 99 crossing River This improvement will rehabilitate the existing 24-inch diameter trunk. Rehabilitation - 24 - 300 City Wide Projects SDR Storm Drain(1) Various Locations This improvement will remove storm drain connections from the sewer collection system. Storm Drain Removal - - - - R&R Rehabilitation & Replacement(1) Various Locations These improvements will help carry out the Small and Large Diameter Rehabilitation and Replacement Program. Rehabilitation - - - - Notes: Project is carried forward from the 2007 Master Plan and City’s CIP. Projects are carried forward from the PDR. ---PAGE BREAK--- ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-7 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx 8.2.2 Reliability Projects 8.2.2.1 Area 3 • Sutter Trunk (Project S-4a): This project is carried over from the 2007 Master Plan and the City’s CIPP (Project S-4a). The Sutter Trunk crosses Highway 99 as a 16- inch diameter pipeline near Jefferson Street and has a high consequence of failure. Project S-4a consists of constructing 400 feet of 16-inch diameter pipeline parallel to the existing sewer under Highway 99 to increase reliability. • River Bank Armament (Project RT-11): This project is carried over from the PDR and recommends riverbank armament to prevent future erosion and exposure of the River Trunk and the CSL. Due to erosion, some segments of the CSL have lost all soil cover and pipe support. Segments of the River Trunk and CSL that parallel the River have an extremely high consequence of failure and require additional protection along the River Bank. • CSL Diversion Structure (Project RT-12): This project is carried over from the PDR. West Yost Associates (West Yost) prepared the CSL and River Trunk Plan Diversion Plan Study, which identified a contingency to divert flows between the CSL and River Trunk. The diversion structure will allow the City to increase the CSL's capacity under extreme flow events and divert 100 percent of the flow if either pipeline fails. 8.2.2.2 Area 8 • Ceres Trunk (Projects C-2a, C-2b): These projects are carried over from the 2007 Master Plan and the City’s CIPP (Project C-2a,b). The Ceres Trunk crosses Highway 99 as a 24-inch diameter pipeline and has a high consequence of failure. Project C- 2a consists of constructing 300 feet of 24-inch diameter pipeline parallel to the existing sewer under Highway 99 to increase reliability. Project C-2b consists of rehabilitating 300 feet of existing 24-inch diameter pipeline under Highway 99. 8.2.3 Citywide Projects • Storm Drain Cross Connection Removal (Project SDR): These projects are carried over from the 2007 Master Plan and the City’s CIPP. In areas without permanent storm drain systems, the City utilizes the sewer to drain stormwater runoff to reduce flooding. After a storm event, these cross connections dramatically increase PWWF. There are 60 known storm drain cross connections within the City, with most located downtown and northwest. Removing them will significantly reduce storm drainage into the sewer system and scale down the peak flows. However, before the storm drain cross connections can be removed, trunk lines and laterals must be constructed to convey stormwater to existing facilities or new detention basins. ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-8 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx • Rehabilitation and Replacement Program (R&R Program): These projects are carried over from the City’s CIPP. This program will rehabilitate and replace small diameters and large diameter pipelines throughout the City. The purpose of the R&R program is to identify sewer infrastructure susceptible to failure or exhibiting corrosion and deterioration. Rehabilitation can involve removing and replacing the existing infrastructure, installing a liner, or making point repairs. This program will extend the lives of existing sewers and maintain operation of the collection system. 8.3 PROJECT PHASING Criticality ratings were assigned to each pipeline reach to identify sewers with high likelihood and consequence of failure. Pipelines were then inspected and graded according to their physical condition. As part of the prioritization effort, the structural and O&M rating of pipeline reaches were utilized to identify the most critical sewers. The four priority levels assigned to each project are as follows: • Level A: Improvements targeted for the first phase should be completed in the early stages of the CIP. These projects include: - Rose and Celeste/Santa Rosa Trunk (Project A-1). - Sutter and South Trunk (Project A-2). - West Trunk (Project A-3). • Level B: The second phase targets projects that should be completed within three years. These projects include: - Crows Landing (Project B-1). - Emerald Trunk Tributary (Project B-2). • Level C: The third phase targets lower priority projects that could be completed within five years. These projects include: - West Trunk (Project C-1). - Sutter Trunk (Project C-2). • Level D: The final phase addresses projects considered low priority and can be completed within five to ten years. These projects include: - Downtown Tributary Trunk (Project D-1). - Emerald Trunk Tributary (Project D-2). The phasing for projects carried over from the 2007 Master Plan, PDR, and the City’s CIP are in Chapter 9. ---PAGE BREAK--- April 2016 - FINAL DRAFT 8-9 pw://Carollo/Documents/Client/CA/Modesto/9704A00 - WW Collection/Deliverables/CH08/Ch08.docx 8.4 ADDITIONAL RECOMMENDATIONS As part of the Trunk Sewer Condition Assessment program, the Rumble, Sonoma, and Upper portions of the Lakewood Trunk sewers have unlined RCP that were not inspected. At a minimum, PoleCam photographs should be taken on trunk manholes to obtain representative samples of the connecting pipelines. ---PAGE BREAK---