No utility wants to shut off service or advise its customers to boil water. No one wants to shut down traffic on busy streets or hear that area homeowners have flooded basements, but this is what can happen when a utility experiences two water main breaks in one week, as Capital Region Water (CRW) did one wintry weekend.
CRW knew it needed to fix the aging cast iron pipes in this area, but workers also knew it would be a significant challenge. The area in question was in the heart of Pennsylvania’s state capital. The road above these pipelines carried thousands of vehicles per day to Interstates 81 and 83, the community college, the Pennsylvania Farm Show Complex, and government buildings. It was a concrete route owned and maintained by the state, and pavement restoration costs would be high.
The water mains in Cameron Street were installed in the 1890s, and Capital Region Water needed a way to improve the structural integrity of the water mains while avoiding traffic disruption and minimizing costly pavement disturbance. CRW leaders thought cured-in place-pipe (CIPP) lining could be the answer.
CRW operators and engineers were familiar with cured-in-place-pipe lining for sewer rehabilitation. However, they had never used it for a water main because lining used for water mains is different than that used for sewers. Water main pipelines have to resist soil pressures around the exterior pipe, as sewer line does, but they also have to resist the internal pressure of flows pushing out.
Therefore, CIPP lining for water mains typically has fiberglass or a similar material inside to provide additional strength. It also requires different resin for the curing process, a resin that meets NSF 61 requirements and is safe for potable use. However, unlike open cut trenching, contractors installing CIPP lining do not have to dig up the entire roadway. They only need to open a few access pits. This would be a huge advantage at this location given that it is a concrete road surface as opposed to bituminous pavement.
This procedure would save CRW money on pavement restoration and make it easier to maintain traffic through the heart of the city. Contractors can do the work at night and cover the access pits with steel plates during the day, so cars can travel through the area at reduced speed.
CRW asked its engineer to investigate the use of CIPP lining for the water distribution main along Cameron Street, and the engineer’s experience provides several good lessons to other utilities about how to ensure a successful water main rehabilitation project.
Determine Pipe Condition
Before planning a pipeline rehabilitation, determine the condition of the existing pipe as accurately as possible. Begin by examining its history of leaks and repairs and, perhaps, also extract a sample of the pipe to study the number and spacing of pits. Alternatively, use remote field technology to examine the inside of the pipe for signs of corrosion, weaknesses or…
Read more:: 7 Lessons for Pipe Rehabilitation