Site work for a water / sewer project in Boise, Idaho. Completed plans call for site work for a water / sewer project.

SCOPE OF WORK Project Background - During coating repair work inside WBWRF Primary Digester 2 it was discovered that the piping inside the digester has experienced corrosion and 2 of the pipes have developed leaks. The piping needs to be repaired and/or replaced before placing the digester back into service. Question Submission Close Date 2/26/2024 2:00 PM MST Piping flow conditions - Summary of pipes inside the digester (left to right on the photo in WBWRF Primary Digester 2 interior piping repair scope) - 12" pipe in the upper box is used as the transfer pump discharge - 8" pipe in upper box is not in use - One of the 6" pipes in the upper box is not in use - One of the 6" pipes in the upper box is the transfer pump outlet - 12" pipe in the upper box is the active overflow pipe - 12" pipe in the lower box is the feed pipe used to roll the digester contents Feed sludge and heated sludge is delivered to the digester via the pipe routed up the exterior of the digester and down through the roof. The overflow pipe has developed a leak near the floor of the digester. The lower gravity box serves as the overflow for the digester by sending sludge through a hole cored in the wall between the 2 gravity boxes. The repair work scope is; - Remove the unused 6" pipe (upper box) from the bottom of the box to the grooved connection near the floor. The pipe stub through the floor will be capped at the grooved connection. A method will need to be developed to seal this pipe opening in the upper box. - The 8" pipe in the upper box will be removed down to the floor stub and be capped at the grooved connection. A method will need to be developed to seal this pipe opening in the upper box. - The second 6" pipe (upper box) will be removed from the upper box down to the lower grooved connection. The pipe penetration through the box will remain in place and connected to the piping inside the box. The piping in the box will be modified by adding a check valve that will keep air from exiting the digester interior and allow air to enter the digester when lowering the sludge level. - Install a 90 degree elbow on the 6" second pipe floor stub. - The 12" outlet pipe from the upper box will be removed up to the upper box. A method will need to be developed to seal this pipe opening in the upper box. - The 12" overflow pipe will be surface repaired at the hole near the floor and remain in service. - The 12" pipe used to roll the digester sludge will be replaced with a 10" stainless steel pipe. The existing 12" pipe through the bottom of the lower box will be used as a sleeve to route the 10" stainless pipe into the lower box. This new 10" pipe will be flange connected inside the digester in 10 foot or shorter lengths to allow easier installation and avoid welding inside the digester. The flanged pipe lengths will be fabricated outside of the digester. The top section of this piping will be continuous from the bottom of the box to at least 2 feet below the lowest sludge surface level. This will place the first flange connection under the sludge level rather than in the gas bonnet.