Mount Woodson Reservoir Floating Cover Replacement

LOCATION: Ramona, California  PRODUCT: Tensioned Cable Cover Design MATERIAL SUPPLIER AND INSTALLER: Layfield Geosynthetics

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PROJECT SUMMARY

  • Owner:  City of Ramona, California
  • Project Name: Mount Woodson Reservoir Floating Cover Replacement
  • Capacity:  10 Million Gallon (38,000,000 liter) 
  • Application:  Potable Water Storage
  • Scope:  Replacement of 29-Year-Old CSPE Floating Cover

Figure 1  Picture of completed new 45 mil CSPE Floating Cover with Tension Cable Tower System
Figure 1  Picture of completed new 45 mil CSPE Floating Cover with Tension Cable Tower System

The City of Ramona Municipal Water District had originally planned as part of their longer-term capital planning budgets to replace an existing 29-year-old 45 mil CSPE floating cover in the next two to three years.  However, as part of a strategic risk management review of their existing water storage facilities, they decided to move forward with this requirement early in 2020. 
 
The project scope required the demolition and removal of the existing 29-year-old CSPE cover and the supply and installation of a new replacement 136,000 ft2 (12,640 m2) 45 mil beige/tan CSPE floating cover.  The project faced several logistical challenges, including a very limited working area on-site and not being able to take the existing reservoir out of commission during the installation of the new cover system.  This was a requirement in order to prevent the treated water from being exposed to environmental contamination during construction.  To fulfill this requirement, the existing cover had to be removed simultaneously and in sequence with the new cover installation.  This required that we weld the leading edge of the new cover material directly to the end of the old cover material.  As the old cover was pulled off the reservoir, the new cover was floated into place.  The irregular shape of the reservoir and limited access space prevented us from being able to deploy and weld the large prefabricated floating cover panels.  To address the tight space constraints, Layfield constructed a scaffold supported 14,000 ft2 (1,300 m2) wood platform located at the northwest corner of the reservoir.  As the reservoir was situated on the side of an embankment, this required 16’ to 20’ (4.9 to 6.1 m) high vertical scaffolding and shoring be designed and erected to support the working platform.  This platform provided the additional work area required to stage, unroll, and weld the prefabricated panels for the new floating cover.