Underwater Grout Repairs
July , 2019
Global was contracted to perform maintenance and underwater grout repairs to three waste gates at Ryan Dam in Great Falls, MT. The 5-person dive team consisted of the Dive Supervisor and four divers. The surface dive spread and decompression was based on a 30’ x 30’ EZ Float barge. The Dive Supervisor directed operations from the Surface Control Van located on top of the dam, maintaining communications with topside crew, crane operator and diver at all times. The maximum water depth was 70 feet of fresh water; when adjusted for the elevation of 3,000 feet the equivalent depth is 90 fsw, limiting bottom time to 90 minutes.
Working ten hour shifts, the crews cleaned the areas of eroded concrete and voids around the thimbles of Waste Gates 1, 2 and 3, removing all growth and silt that might inhibit the new grout from bonding to the existing surface. The team then installed and anchored form materials over the voids at Waste Gates 1 and 3 and sealed them with Splash Zone epoxy; once the forms were installed the voids around the thimbles were pressure grouted using US Spec MP grout. While on site, Global’s divers also performed a general survey of the other seven waste gates at the dam.