18-08-2015, 07:06 PM
Some questions about the renewal systems that you need to address:
• Life of the renewal system.
• Range in diameter of pipe sizes that the liner can be used in.
• Velocities that they can handle.
• Abrasion that they can handle (Abrasion resistance?) 5. Can they be used to reline pipes with bends between 45-90 degrees?
• Are they structurally independent of the host pipe?
• Is there a limitation to depth of cover?
• What is the Manning’s N associated with the finished interior surface of the liner?
• Are inflow/infiltration eliminated?
• What are the access needs for installation?
This particular situation involves multiple discharge pipes of varying sizes at a levee pump station. These pipes follow the profile of the levee and therefore have multiple bends. These are steel pipes with an unknown existing thickness but are not deteriorated enough to have any holes in the pipes. See the attached document and below notes for a more detailed explanation.
1) GR001 - General exterior photo views of the pump station location
Page 1 of 4 Pages
2) PS2-CS102 - Site Plan for the pipes to be lined
3) PS2-CS501 - Arrangement of the pipes at the levee crown
4) PS2-M-102 - Arrangement of flap gates at the discharge end of the pipes (Note conflict with PS2-CS102 and PS2-CS501 for diameter of smallest pipe).
5) PS2-M-103 - Detailed Pipe Geometry (Note conflict with PS2-CS102 and PS2-CS501 for diameter of smallest pipe)
6) PS2-M-601 - Photos taken inside the pump station wet well, and on pump machinery floor.
7) PS2-M-602 - Additional general exterior photo views of the pump station location (Photos A1, A7, D1, D4 not applicable to lining scope).
8) PS2-E-301 - Section view of Pump Station. Lining will extend into the pump station to the pump discharge elbows. Pumps likely will be removed when lining is done. Two separate mobilizations to the pump station appear likely, since only two of the large diameter pumps can be removed at one time.
We expect that pipes within the pump station wet well, through the pump station wall to the first coupling outside the pump station could need to be replaced due to severe corrosion and would need to provide a sound pipe connection to the pump discharge elbow. We also anticipate that the pipes penetrating the discharge headwall could need to be replaced to the first coupling behind the headwall. This may not be necessary if the renewal system can address expected loss of pipe section due to sediment accumulation and resulting corrosion.
The pipes carry varying concentrations of combined sewer outfall and/or sanitary sewer treatment plant effluent. Both abrasion and chemical reaction are concerns for pipe life. We expect the lining to last 50 years.
Expect work to be accomplished during dry months with low river elevations and no flows though the pipes. Photo A4 on PS2-M-602 indicates the condition described.
As part of your report you must provide a brief narrative explaining the rationale and justification as to the construction methodology selected by your team. Also, you must include all calculations, in a neat methodical outline demonstrating the iteration cycles performed by your team to optimize the crew equipment combination selected for use on the project. Consider environmental factors and list any assumptions and their justification as necessary.
1. Methodology
The following data is available:
• As-built plans of the existing storm drain system, including the standard pipe cross-sections provided in as-built.
• CCTV inspection.
1.1 Method Selection Process
For evaluation of the appropriate renewal alternatives, the following selection criteria can be established. Draw a decision support system for method selection.
• Applicability. Applicability represents qualifications of renewal methods in three areas: reliability, application, and application to the required diameter and pipe material. A long-term reliability of the renewal method is one of the more important evaluation criteria. The ability to prevent formation of new cracks and the eventual failure of the pipe must be examined under this criterion.
• Constructability. The construction requirements of each alternative can be evaluated based on shutdown requirements; pit requirements; work space requirements; production rate; ability to accommodate bends; risk of damage to levee; availability of local expertise, and quality assurance and quality control and inspection requirements.
• Life Expectancy. An important criterion is the life expectancy of the renewal method to add a new design life, or replace the existing sewer with a new parallel pipeline.
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• Pipeline Hydraulic Capacity. Some renewal alternatives may alter the interior surface frictional characteristics of the force-main and also reduce the cross sectional area. These changes may increase the head loss and decrease the pipeline capacity.
• Structural Integrity. These criteria address structural issues of the renewal system including improvement to the structural integrity, ability to accommodate future pipe settlement or ground movement, offset or displacements, seismic resistance, and ease of repair in case of a pipe break.
• Capital Cost. Capital costs include only the cost for implementing the renewal project.
• Life-cycle-cost. Life-cycle-costs include capital cost, annual operations and maintenance (O&M) cost, social costs (including environmental impacts), and cost of emergency repairs.
