Emergency 72" Manhole Replacement - Atascocita, TX


1. Project Location:  Trail of the Lakes, Atascocita, TX

2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion: 72” manhole with force main, fully deteriorated manhole removed and replaced. 30” line had a complete failure blocking the flow to the sewer plant., 20’ deep

3. When was it constructed and how long has it been in service: Unknown

4. Rehab method used: Prior to installation of the Danby liner, the contractor installed 20 VF of liner plate, then began reconstructing the manhole with a double mat of rebar then installed Danby PL3E flat panels and 1’ thick structural concrete in walls.  The 12” force main was tied in using a custom fabricated HDPE force main drop.  An 8’x8’x18” thick concrete manhole lid was also constructed with the underside having the corrosion resistant Danby PVC liner.    This manhole was constructed by Boyer, Inc. of Houston, Tx

5. Cleaning method used (if required) and who cleaned the line: N/A – Manhole was excavated out

6. Method of flow bypass or diversion, if used: Temporary flow diversion of the upstream pipe directly to sewer plant

7. Depth of pipe: 20 VF

8. Depth of ground water: N/A.

9. Ventilation and odor control used: Forced Air provided fresh air in the shaft

10. Construction cost (total amount and cost per foot): $298,002

11. Month and year of start-up and end of construction: 5-2017 to 7-2015

13. Problems encountered after construction: 1) Prior to construction, a utility pole 10' from manhole was in jeopardy of sinking with the surrounding ground sloughing off.  2) Remove blockage in 30” downstream line, reinforced with steel pipe, CIPP full from manhole to sewer plant

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

15. Has any re-inspection been performed?  Yes, found to be in excellent condition

 

Reference:

Brown & Gay Engineers, Inc.

281-558-8700