Steam condensate line repair may affect pedestrian traffic

This week work is scheduled to repair up to 130 feet of five-inch pumped steam condensate line under Massachusetts Avenue at Vassar Street. The repair will be made using a “trenchless” technique that creates a new pipe within the existing line, and avoids the need to excavate or disrupt traffic.

Work will begin on Wednesday, Dec. 15, and weather permitting, should last three to five working days. During construction, both Massachusetts Avenue and Vassar Street will remain open to vehicle traffic. However, some minor detours of pedestrian traffic will be necessary. Police details will be in place as necessary and all detours will be clearly marked and meet ADA accessibility requirements.

The project consists of several tasks:

• MIT Department of Facilities Utilities personnel will shut down the line, open the manholes on either side of Massachusetts Avenue and will create access points at each end of the line.
• Bluewater crews will survey the line with a closed-circuit, tractor video camera to determine the location and extent of damage to the line.
• Bluewater will then use high-speed water jetting and other techniques to clean, de-scale and prep the pipe for lining.
• A fabric liner will be fitted around an inflatable bladder, saturated with 3P (polyurea-polysilicate-phosphate) resin and inserted into the pipe while it is still pliant. Once the bladder is inflated, the new line will expand to fit, and adhere to, the original pipe.
• After the new line cures and hardens — a process that takes from eight to 24 hours depending on the ambient temperature — the bladder will be removed and a final camera inspection performed, with results recorded on DVD.