4800LF pipe abandonment

4800LF pipe abandonment by CJGeo using cellular concreteChallenge:

4800LF pipe abandonment was required on a 12″ sanitary sewer main replacement project on a military facility.  The stretch of pipe requiring abandonment started on base, and then ran down the shoulder of an interstate.  The owner specified abandoning the sewer line in place using flowable fill, with a maximum distance between placement points of 200LF.

Limits:

The exact path of the sewer line was unknown.  While as-builts existed, they didn’t appear to be accurate.  The pipe crossed on and off base, and at times ran under the interstate.  This all made complying with the specified 200LF distance between placement points exceptionally difficult.  

Additionally, mission-critical communication lines, the new sewer line, water service and large diameter gas lines all ran in close proximity to the sewer. 

The general contractor had two locations they knew they could access the pipe; the upstream end, and at the 3600LF mark.  The 3600LF mark location was just a few feet off the right lane of the interstate, so work in that location had to be performed during road closures.  

4800LF pipe abandonment using cellular concreteThe Solution:

CJGeo proposed cellular concrete as an economical, non-disruptive alternative to traditional flowable fill.  Cellular concrete is exceptionally flowable & pumpable.  CJGeo proposed a 35PCF wet cast density mix, which provides an average compressive strength exceeding 200psi.  This mix has a viscosity of around 200cps, which helps to ensure low pumping pressures over exceptionally long distances.

Result:

CJGeo successfully grouted the two stretches of pipe to complete the 4800LF pipe abandonment project on time and on budget.  The 1200LF stretch of pipe was abandoned the first day.  The next working day, the 3600LF stretch of pipe was abandoned.  Pumping pressures never exceeded 10psi on the short stretch, and were below 20psi on the long stretch.

Due to the low volume of the project, truck batching was used in order to generate the cellular concrete.