Harbour Island Force Main Replacement Design – Build Project Community Task Force Meeting August 24, 2018
Project Update • The City’s intent is the get the pipe off Harbour Island • Alternative 4 (rehabilitation) is the option of last resort • The test results on the existing pipe are not showing significant deterioration • WHAT DOES THIS MEAN - We have time to design and construct a pipeline off the island • The City has purchased the major components to bypass the existing pipeline in the event of an unlikely emergency
Agenda • Project Update • Existing Force Main Condition Assessment • Wall Thickness Testing Results • Recommendations • Update on Route Alternatives Study • Route Alternatives 4, 7(a), 7(b) and 8 • Timeline and Coordination • Next Steps • Questions
Pipeline Testing Locations * Wall thickness testing was conducted by Vector Corrosion Services (VCS) and was contracted by Kimmins Contracting
Pipeline Wall Thickness Testing Conditions ALL LOCATION EXCAVATIONS • Approximately half of the pipe surface was exposed • Pipe thickness was measured at the crown, shoulder, springline and haunch
Testing Location (1) • Located along Knights Run Ave. • Section of pipe is pre-stressed concrete cylinder pipe (PCCP) RESULTS TEST LOCATION PIPE THICKNESS ORIGINAL WALL (INCHES) THICKNESS (INCHES) Crown 5.2 5.25 Shoulder 5.0 5.25 Springline 5.0 5.25 Haunch 5.2 5.25
Testing Location (2) • Located in easement near Harbour Passage Way • Section of pipe is reinforced concrete pipe (RCP) • Selected where gas accumulation would be most likely – designated high point near existing air release valve RESULTS TEST LOCATION PIPE THICKNESS ORIGINAL WALL (INCHES) THICKNESS (INCHES) Crown 5.1 5.5 Shoulder 5.2 5.5 Springline 5.2 5.5 Haunch 5.4 5.5
Testing Location (3) • Located near southeast tip of island • Section of pipe is reinforced concrete pipe (RCP) • Selected where gas accumulation would be most likely – just before the high point where the pipeline begins to descend beneath Sparkman Channel RESULTS TEST LOCATION PIPE THICKNESS ORIGINAL WALL (INCHES) THICKNESS Crown 5.0 5.5 Shoulder 5.1 5.5 Springline 5.0 5.5 Haunch 5.0 5.5
Engineering Assessment • Data from the specialty sub-consultant does not appear to indicate significant corrosion was present at the testing sites. • Based on wall thickness test results, the Project Team is moving forward to further study route alternatives 4, 7(a),7(b), and 8 with the intent of getting the pipe off the island • A variance of these route alternatives may be considered and designed depending on what is found during further investigation.
Alternative Route 4 - Overview PRELIMINARY DRAFT
Rehab Options for Alternate Route 4 • The Rehab option is the option of last resort • Only if we have fatal flaws on the other three options will this alternative be considered • If it is necessary to pursue alternative 4, installation of a bypass system will be needed to facilitate the work on the pipeline. • The test results on the existing pipe are not showing significant deterioration • In the unlikely event of an emergency, as a precaution, the City has purchased the major components to bypass the line • The Project Team is investigating options for bypassing the flow at locations not on Harbour Island and that only require minimal piping on Harbour Island.
Alternative Route 7(a) PRELIMINARY DRAFT
Alternative Route 7(b) PRELIMINARY DRAFT
Alternative Route 8 PRELIMINARY DRAFT
Harbour Island Work for 7(a), 7(b) and 8 GOAL – TO RELOCATE THE FORCE MAIN OFF HARBOUR ISLAND • These alternatives will require rerouting the pipeline that serves Harbour Island to the new force main off the island • This will require some construction and inconvenience on Harbour Island • Alternatives for rerouting this pipeline are being evaluated • There are still unknowns until a final route is selected
Timeline • Final Route recommendations to City by 10/31/18 • Need to coordinate with other ongoing projects • A timeline for design, permitting and construction will be presented once a final route is selected
Next Steps ✓ Public Meeting #2 – Thursday, August 30, 2018 • Present Existing Pipeline Wall Thickness Test Results • Provide Update on Route Alternative Study – Route Alternatives 4, 7(a), 7(b) and 8 • Gather Public Input ✓ Harbour Island Community Task Force Ongoing Meetings ✓ Public Meeting #3 - TBD • Present Final Route Selection
Q & A Project Website: www.hiforcemain.com Project Hotline : (813) 235-4830
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