1. Project Location: Downtown Houston, Texas. Pipe runs under Austin Street, near the Convention Center and was part of the Grand Prix racecourse in October 1998.
2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion: 108", Concrete block built-in-place pipe, 655 linear feet; also approximately 60 feet of 120".
3. When was it constructed and how long has it been in service: Unknown age. Cracks in crown and about 30° from invert possibly caused by nearby excavation causing loss of side soil support.
4. Rehab method used: Danby Panel Lok with full annulus grouting with cementitious grout with minimum compressive strength of 5000 psi. Also used external grouting to consolidate side soil support.
5. Cleaning method used (if required) and who cleaned the line: High pressure (10,000 psi) water blasting performed by the Danby licensee (Kinsel Industries, Inc.).
6. Method of flow bypass or diversion, if used: None.
7. Depth of pipe: 15 feet to crown.
8. Depth of ground water: Five (5) feet of ground water above pipe invert.
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.
10. Construction cost (total amount and cost per foot): $750,000 ($9.62/ID in-ft).
11. Month and year of start-up and end of construction: August 15-October 30, 1998.
12. Problems encountered during construction: In addition to the cracks, there were several abrupt offsets in the pipe alignment (mostly vertical); at one point, for example, there is the equivalent of a "dropped joint" where the flow channel has a vertical dimension of only 94" while the horizontal diameter is 108". Twelve inches downstream from this point the pipe returns to approximately circular with a diameter of 108". Hurricane induced rains produced surcharge flows when the project was about 75% complete (about 550ft lined, only about 400ft with various grout levels). All work in progress survived without damage.
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.
Gary Oradat, P.E.
City of Houston (Now with Coastal Water Authority, Tel: 713-658-9020)