DC Water is Utilizing Cured-in-Place Methods to Rehabilitate Aging Underground Sewer Laterals in the Nation's Capital

DC Water provides critical water and sewer services to the Nation's capital and similar to many older cities the infrastructure that supports these services is old and deteriorating. The median age of the 1,800 miles of sewer pipe is 86 years old with some in-service trunk mains installed before the Civil War. DC Water is committed to replace 1% of the collection system annually; however, even at this accelerated pace it will take 100 years to replace the system before our successors start up all over again. DC Water is also responsible for maintaining the approximate 150,000 sewer laterals in the public space and we replace 400 sewer laterals per year as part of an ongoing program to address multiple backups. The lateral replacement program is done by a combination of internal crews and contractors. The conventional open cut method of construction is used with a typical crew size of six to install one lateral and a cleanout. Restoration costs associated with this program are a major cost driver for DC Water primarily because the District of Columbia's landscape is largely urban with far more asphalt, concrete and brick than green space. The typical installation takes four (4) days to complete and the average cost of a lateral replacement is $11,200 including restoration. One of DC Water's strategic initiatives is to evaluate different technologies to improve service delivery while lowering our asset life cycle costs. The lateral program seemed a likely candidate to evaluate trenchless solutions since over 20% of the project costs were related to restoration. DC Water staff were interested in a trenchless solution; specifically, a cured in place pipe (CIPP) solution as a possible alternative to the traditional open trench method for obvious reasons.