1. Project Location: Main line into the East Bay Municipal Utility District's treatment plant in Emeryville, California; serving the entire east bay region (Oakland) of the San Francisco Bay area.
2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.) length of rehab portion: Diameter = 105"; RCP, 352'.
3. When was it constructed and how long has it been in service: Unknown, not stated in contract documents.
4. Rehab method used: Danby Panel Lok III in top portion of pipe from 12" below the pipe centerline, with full annulus grouting with cementitious grout with minimum compressive strength of 5000 psi. Prior to installing liner, 4"x4"x1/4" welded wire mesh was mechanically fastened to pipe wall in those areas were the wall corrosion exceeded 2".
5. Cleaning method used (if required) and who cleaned the line: High pressure (18,000 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: 25 feet.
8. Depth of ground water: 12 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): $268,800 / $764/ft
11. Month and year of start-up and end of construction: April 1993 - May 1993 (6wks); work hours were restricted to 1 a.m. to 5 a.m.
12. Problems encountered during construction: Significant diameter increase at crown after high pressure water blasting due to corrosion created enlarged annulus far exceeding the original estimate of surface wall loss; thus increasing the amount of welded wire mesh and grout required to meet the specification. Also, in these very large diameter pipes the grouting must be done in many more "lifts" (to limit vertical rise per lift) to avoid deforming the PVC liner.
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? East Bay MUD did a walk-through inspection of this pipe section on July 24, 1997 and again in 2015 and found the liner to be in great condition and has prevented further corrosion in the lined section.
Elsabeth Girma, P.E.
East Bay Municipal Utility District