In Case of Emergency


Heavy Civil Mechanical

Project Name

Colgate Penstock Shut-off Valve Installation



Year Completed


Location Information

Dobbins, California

The project com­prised the instal­la­tion of a 168-inch but­ter­fly valve in the Col­gate Pen­stock. The scope of work includ­ed: mod­i­fi­ca­tion of the exist­ing pen­stock, relo­ca­tion of air release valves, and instal­la­tion and com­mis­sion­ing of a flow-meter and hydraulic sys­tem. The project involved exten­sive mod­i­fi­ca­tion to the exist­ing 14-foot diam­e­ter pen­stock to accept the instal­la­tion of the 168-inch but­ter­fly valve. All weld­ing and fab­ri­ca­tion was com­plet­ed under ASME Boil­er & Pres­sure Ves­sel Code VIII and Weld­ing & Braz­ing Qual­i­fi­ca­tions IX.

Key Chal­lenges

The crit­i­cal dead­line for the project was Decem­ber 8th, by which time the pen­stock need­ed to be recom­mis­sioned to allow the pow­er plant to be returned to nor­mal oper­a­tion. Fail­ure to meet the dead­line would have result­ed in liq­ui­dat­ed dam­ages of $25,000 per day for the first 8 days and $3,000 per day there­after. The two crit­i­cal phas­es of work were the pen­stock mod­i­fi­ca­tions and instal­la­tion of the 168-inch but­ter­fly valve.

The major challenges and risks associated with the project included:

  • Operating within a 9-week schedule.
  • Maintaining critical alignment of the penstock during modifications.
  • Fabrication of the spool sections at an offsite facility located in Bakersfield.
  • Relocation of the butterfly valve from its temporary foundation to its permanent foundation in-line with the penstock.