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60” x 70” Semi-Elliptical Sewer


1. Project Location: West Los Angeles Interceptor Sewer Rehabilitation & Venice Jasmine Diversion Sewer W.O. E2000743 & E2000822, Culver City, California.

2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion: 60” x 70” Semi-Elliptical Sewer made of unreinforced concrete; project length of 3,750 linear feet. Severe corrosion in crown of sewer (as much as 5” of the 7” original wall thickness).

3. When was it constructed and how long has it been in service: Cast-in-place construction in the early 1900’s.

4. Rehab method used: Danby Panel Lok with full annulus grouting with cementitious grout with minimum compressive strength of 5000 psi. Panel Lok flat panels arched from “J” strip anchors at invert corners. No lining of invert.

5. Cleaning method used (if required) and who cleaned the line: High pressure (10,000 psi) water blasting performed by the Danby licensee (Stacy & Witbeck, Inc.).

6. Method of flow bypass or diversion, if used: Full bypass pumping of 21 MGD flow.

7. Depth of pipe: 5 to 20 feet to crown.

8. Depth of ground water: No ground water.

9. Ventilation and odor control used: Fresh air pumped into pipe at upstream manhole, and suction fan at downstream manhole to provide adequate ventilation during the work periods. Odor control of exhaust air as required by City.

10. Construction cost (total amount and cost per foot): $3,742,000 / $1,000/ft (includes approximately $1,400,000 in bypass cost).

11. Month and year of start-up and end of construction: June 1997 – June 1998.

12. Problems encountered during construction: Initial specifications required monolithic grouting that, in turn, required formwork. Use of wood forms impeded cooling at the PVC surface resulting in excessive temperature differential across the grout thickness that resulted in cracking of the grout (high cement content produced high heat of hydration). Removal of forms and stage grouting resolved the problem. Grout cracks repaired by injecting epoxy grout.

13. Problems encountered after construction: None.

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

15. Has any re-inspection been performed? What was the condition of the pipe? No.


Reference:

Steve Nakaido, P.E.

Collection Systems Engineering Division, City of Los Angeles

Telephone: 213-847-8430