Install Water Control Devices cover drilling, development drilling or when production drilling. During probe-hole or grout-hole/water cover drilling, the necessary water control devices must be on hand. If a water bearing structure is intersected whilst development drilling or production drilling, these should be immediately stemmed to reduce the inflow of water. The Grout Crew/Services Supervisor is to be contacted immediately to determine the best course of action to control the water source. Some water inflows encountered whilst drilling development holes may have significant high volumes and high pressures. In some cases the water inflows can only be estimated (not measured by normal methods, i.e. buckets & stopwatch) by engineering staff at greater than 20 l/s. With such high inflows, it is impractical and too dangerous to insert packers by hand. Inflows such as these require the packer to be installed by mechanised means, i.e. with the use of the jumbo and other attachments / dollies. All water control devices are to be checked for damage, cleanliness, are to be free of obstructions and operate correctly before installation. 2.1. Temporary Water Control Device 2.1.1. Tapered Plug The primary function of the tapered plug is as an interim water controlling device, to prevent inundation of the pumping system (see picture below). It is installed with a Jumbo drill rig and is used to stem the flow of water, until the permanent water controlling device is selected then readied and installed. It is a semi flexible, conical shaped plug, constructed from polyurethane and moulded onto a 45mm drill bit with an R32 internal thread. There are two sizes of plugs that can be used to suit 64mm and 45/48mm drill holes. The standard drill steel size at Didipio for the tapered plug is 4.9m with an R32 bit thread; however any length steel with an R32 bit thread can be used. Figure: Tapered Plug 2.1.2. Inserting Tapered Plug If a water bearing structure is intersected during drilling with a Jumbo, take note of the intersection depth and remove the drill string from the hole. Move the Jumbo boom to a safe position away from the water flow and load a tapered plug onto the drill steel. Move the Jumbo boom with the tapered plug to the hole collar and using the Jumbo’s drill feed, insert it into the hole until it comes to a stop. The Jumbo boom, drill steel and tapered plug now act as a temporary water control device. It is only retracted when the permanent water controlling device is ready to be inserted; or in the case
RkJQdWJsaXNoZXIy MjE2NDg3