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Department of Public Works

Cured In Place Pipe (CIPP) Facts

The Water Resources Division of Burlington DPW regularly hires contractors to repair and rehabilitate gravity sewer pipes (sanitary, combined wastewater, and separate stormwater) using CIPP technologies. Since approximately 2009, the City has preferred this method to traditional open cut/dig and replace methods because 1) Pipe rehabilitation using CIPP takes a fraction of the time compared to replacement, 2) Impacts to the Right of Way are minimized (traffic, pedestrians, bicycle, etc.) and 3) CIPP installation is often more cost effective.

Installation Overview

  • Contractors will perform a cleaning and pre-lining CCTV inspection of the pipe to document measurements and locations of lateral connections.
  • The Contractor will provide notification to the impacted customers, typically 1-week before the start of work and then a second notification 24-hours before the contractor performs the work.
  • 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. 
  • 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 (depending on the curing time) and are asked to limit water usage. Curing times depend on a variety of factors, such as host pipe       material, size of pipe and the thickness of liner being installed. Typically the Contractor will request a service disruption of 8-hour work day.
  • Once the liner has fully cured, the contractor will cut both ends of the liner and re-instate laterals with a robotic tap cutter.

Possible 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 epoxy-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.  The pathways for odor migration are either through dried-out sewer gas traps in the home or open windows adjacent to this work in the street. 

Styrene odors can be detected by humans at a significantly lower concentration (0.05ppm to 0.08ppm)1 than what is considered to be a human health concern (Acute Exposure Guideline Level-1 of 20ppm limit)2. However, we understand that the odor can be concerning and that certain individuals may be more sensitive to the smells and so strongly encourage owners and tenants to understand how to prevent any intrusion of odors into a property and so are providing information both on how to prevent the odors from entering, as well as what to do in the event if you do smell the odors.  Given that odors are present at very low concentrations, if you do not smell the odor (unless you have impaired smell) – it is highly unlikely that the styrene is present.

Customers that have the potential to be impacted will receive two notifications (the first typically 1 week before the work, and then another 1 day before project start) so that they can implement these preventative measures.

Odors can enter the home through floor drains, toilets, sinks, sump pumps, or other such items that can be connected to the sewer pipe. While less likely, odors may also enter the basement through foundation cracks or the home through open windows. In most cases, the likelihood of this occurring can be minimized through various preventative measures (see below).

Preventative Measures for Owners to Reduce Odors in their Home or Business

Styrene odors are most likely to enter a home due to dry or non-existent plumbing traps, such as floor drains, toilets, sinks, sump pumps, or other such items that can be connected to the sewer pipe. Odor may also enter a residence through foundation cracks or through open windows. In most cases, any odors can be minimized by pouring ½ to 1 gallon of water down the sink, toilet, floor drain, etc.   Keep windows closed along the street side to minimize the potential for outside air migration into your home.

If you detect the odor:

  • Please reach out the contact listed on the work notice
    • All complaints and their resolution will be logged and documented for the City by the Contractor.
    • If you feel that your concern is not addressed, contact the Water Resources Division at 802-863-4501.
  • If your windows were closed during this lining project then it could be migrating from sewer traps or leaky foundation cracks.  Try opening them opposite the street side and leave open if fresh air is coming in.
  • If some of your windows were left open and you smell odor coming in through them, then close them and check other windows to see if you have access to fresh air.
  • The smell is very distinct – but if you have any concern that the smell may be a natural gas leak (e.g. skunky odor, not chemical odor), contact 911 for the Burlington Fire Department.
  • If you feel ill in any way please reach out to your healthcare provider.

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

 

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