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NASA – Focusing on Value Engineering on Terra Firma - August 2003
CLEVELAND – Engineers, contractors and suppliers all say it. "Everything at NASA is special." And NASA wouldn’t have it any other way. The demands placed on the space program necessitate an "only the best" approach. Their demands are no different right here on terra firma (or in terra firma). All of NASA’s capital plant systems are designed and installed with an unwavering focus on quality, coupled with a concern for life cycle costs.
NASA’s demand for quality and long-term value is currently being applied to the design and installation of a new sewer system at the Glenn Research Center at Lewis Field in Ohio. The project is being implemented in a series of six phases at a total estimated cost of approximately $15 million. The system will serve a population of 3,500 to 5,000 in 150 buildings for the next 100 years and longer (based on the life cycle projections of the Army Corp of Engineers).
The old system was vitrified clay pipe (VCP) and was installed by the WPA. The pipes were probably sealed with mortar and okum and now suffered from deteriorating joints. After a TV inspection, the decision was made to replace the existing system to achieve improved hydraulics and increased capacity.
"Joint deterioration can be an issue in clay installations that are of this age," according to Dick Holl, president of Logan Clay Products Company. Prior to the 1950’s the joints were manufactured in the field and the long-term results are as unique as the individuals who did the work. Some installations are over 100 years old and still serving their communities in great shape today. O-ring compression joints were introduced in the mid sixties and in nearly 40 years of using this system, it has met or exceeded all infiltration standards."
"NASA knew they wanted to use vitrified clay pipe with a controlled low-strength material [CLSM] backfill for this installation" said Ron Shaw, P.E. of URS in Cleveland. "I was originally concerned that buoyancy would be an issue, and according to my initial calculations, it should have been."
Mike VanDine, P.E. of the National Clay Pipe Institute agreed, " I did those same calculations and came to the same initial conclusions. But we eventually found that the CLSM has a lower than expected viscosity due to particle size and processing techniques. That, coupled with frictional forces, eliminates concern about buoyancy with clay pipe. With any lighter product it is still an issue, but we’ve used this method on several clay installations now and buoyancy is not a problem."
To enable a gravity-fed system, and to avoid the 24 other underground utilities on this site, the pipe was installed at depths of up to 30’ with CLSM all the way up to sub-grade, or 4’ below in the grassy areas.
"The benefit of this type of installation is that the new compression joints used with clay pipe provide just enough flex to allow for minor differential settlement, and the CLSM will fracture right at the joint interface to enable that flexibility," explained VanDine. "The load-bearing capacity of the pipe isn’t effected by the CLSM above the pipe, but with the CLSM going all the way to sub-grade NASA has installed this system so that compaction and settlement won’t be concerns."
"It was this kind of long-term value engineering that NASA was trying to achieve," said Shaw, " and I think they’ve done a great job. I wish all pipe could be installed this way."
Because of NASA’s focus on quality engineering and long-term value, investments totaling $535 million since the groundbreaking at Lewis Field in 1941 have resulted in a plant with a current replacement cost of approximately $2.2 billion.
The Glenn Research Center at Lewis Field contains a unique collection of world-class facilities involved in the aero propulsion program, micro gravity research and turbo machinery development for NASA. |
