60" and 48" MANHOLE REPAIRS - Cypress, TX

1. Project Location:  Garden Shadows Ln WWTP – Cypress, TX

2. Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion:

  • 60” RCP Manhole with (2) 10” Force Mains, 27 VF – walls were fully deteriorated
  • 48” RCP Manhole, 27 VF

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

4. Rehab method used:

a) This project was deemed an Emergency because 48” manhole had collapsed creating a sinkhole in the surrounding soil.  Prior to installation of the Danby liner, the contractor had to bypass 1 of 2 10” force mains and excavate the remains of the manhole out.  The contractor installed 27 VF of 8’ ID liner plate, then reconstructed the manhole with a double mat of rebar and proceeded to install Danby PLIII 1” flat panels (3½) 8’ vertical sections.  The (2) 10” force main were reconnected using a custom fabricated 24” HDPE force main drop.  An 8’x8’x18” thick concrete HS20 load rated manhole lid was also constructed with the underside having the corrosion resistant Danby PVC liner.    

b) A 48” manhole was rehabbed using Danby PLIII ½” profile spiral wound method.  A 5’x5’x18” manhole lid was constructed with the underside having Danby PVC liner.

This project was done by Boyer, Inc. of Houston, TX

5. Cleaning method used (if required) and who cleaned the line:

a) Manhole was excavated out   b) Hydroblasting with 8K to 10K PSI water pressure

6. Method of flow bypass or diversion, if used: By-pass of (1) 10” Force main, Internal by-pass for the 2nd 10” Force main directly to the 18” downstream line

7. Depth of pipe: 2 manhole 27 VF each.

8. Depth of ground water: N/A.

9. Ventilation and odor control used: Forced air provided for ventilation

10. Construction cost (total amount and cost per foot): $299,750

11. Month and year of start-up and end of construction: 12-2015 to 1-2016

13. Problems encountered after construction: None.

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

15. Has any re-inspection been performed?  No


Alene Efaw

Brown & Gay Engineers, Inc.


a) 60" Manhole - Fully Deteriorated/Collapsed