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102" South Metro Interceptor Rehabilitation - San Diego, California


1. Project Location: Harbor Drive, San Diego, California. This line conveys sewage for approximately one half of the Metropolitan Sewerage System service area plus approximately 10-mgd from Tijuana, Mexico.

2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion: 102", RCP (16-ft lengths), 1200 feet of rehab (plus about 390 feet of repairs to "T-Lock" liner in original pipe).

3. When was it constructed and how long has it been in service: Put into service in 1964; manufactured by American Pipe and Construction Co.

4. Rehab method used: Danby Panel Lok III in top portion of pipe from 12" below the pipe centerline (top 240°), with full annulus grouting with cementitious grout with minimum compressive strength of 5000 psi. Prior to installing liner, 6"x6"-W2.9xW2.9 welded wire mesh was mechanically fastened to pipe wall in the top 90° of the pipe.

5. Cleaning method used (if required) and who cleaned the line: High pressure (15,000 psi) water blasting performed by the Danby licensee (Rondeau Bay Construction).

6. Method of flow bypass or diversion, if used: Constructed work platform over low flow level and partially regulated flow at pump plant.

7. Depth of pipe: 32 feet.

8. Depth of ground water: 5 feet.

9. Ventilation and odor control used: Fresh air pumped into pipe past upstream air dam; maintained sealed lids during non-work periods, and adequate ventilation to carry odors downstream during the work periods.

10. Construction cost (total amount and cost per foot): $702,000 / $585/ft.

11. Month and year of start-up and end of construction: Dec. 1994 - March 1995. Work hours restricted to 1 a.m. to 5:45 a.m.

12. Problems encountered during construction: Heavy rains delayed work, curves in pipeline required customizing panels at pipe joints (every 16 feet), and large diameter required greater care in grouting to avoid deforming liner (no separate form work was used to support liner).

13. Problems encountered after construction: 1999 inspection showed poor installation QC resulted in need for repairs to some joints; 2002 inspection required repair due to over-grouting.

14. Health and safety: Used conventional confined space entry program.

15. Has any re-inspection been performed? What was the condition of the pipe? Inspection performed January 1999; liner was generally in good condition but several joints were poorly installed and needed repairs. 2002 inspection required repair due to over-grouting.


Reference:

Bill Swallow

Clean Water Program for Greater San Diego

Telephone: 858-292-6485