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Department of Public Works

Cured In Place Pipe (CIPP) Facts

 

 

Background: The Water Resources Division of Burlington DPW regularly hires contractors to rehabilitate gravity sewer pipes (sanitary, combined wastewater, and separate stormwater) using CIPP technologies. Since ~2009, the City has preferred this method to traditional open cut/dig and replace methods because:

1. CIPP installation is often more cost effective

2. The time to complete the rehabilitation is drastically less than replacement

3. Impacts to the Right of Way are minimized (traffic, pedestrians, etc)

 

Installation:

1. Contractors will perform a cleaning and pre-lining CCTV inspection of the pipe to document measurements and locations of lateral connections

2. The crews then insert a flexible liner into the original pipe, through a manhole access. At this time, upstream wastewater flows are bypassed to the downstream manhole.

3. The liner is then sealed and injected with water or steam to inflate the liner to the shape of the host pipe and to begin the curing process. During this time, properties that are that directly connected to the pipe being relined will have their lateral pipe connection temporarily blocked off for a few hours (tbd, depending on the curation time)

4. Once the liner has fully cured, the contractor will cut both ends of the liner and re-instate laterals with a robotic tap cutter.

 

Odors During Installation

The CIPP lining method involves the use of a plastic resin, which contains Styrene, to cure the felt liner. Individuals may detect a plastic or glue-like smell when in the vicinity of the work zone. Generally, these odors are confined to the construction area and dissipate quickly, however there is a potential that owners or tenants may experience the odor inside the residence. Styrene odors can be detected by humans at a significantly lower concentration (0.016ppm1 to 0.32ppm2) than what is considered to be a human health concern (50 ppm - Nation Institute for Occupational Safety and Health Recommended Exposure Limit for up to a 10 hour work day during a 40 hour work week; 100 ppm Occupational Safety and Health Administration Permissible Exposure Limit)>

 

Preventative Measures: Styrene odors are most likely to enter a home due to dry or non-existent traps on the private sewer lateral. In most cases, any odors can be minimized by pouring several gallons of water down the sink, toilet, etc. and by venitilating (opening windows, etc).

 

Combined Sewer - Prior to CIPP Rehab Combined Sewer - Post CIPP Rehab

 

Resources:

1 World Health Organization - Styrene

2 EPA - Styrene

 

EPA Resources related to Styrene

Styrene Information and Research Center

Guideline for the safe use and handling of Styrene Based Resins in Cured-In-Place Pipe (CIPP)