Harbour Island Force Main Replacement

Community Task Force Meeting

August 24, 2018

Design – Build Project

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 ConditionsALL 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(INCHES)

ORIGINAL WALL 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(INCHES)

ORIGINAL WALL 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(INCHES)

ORIGINAL WALL 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 8GOAL – 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