Papers & Tech Notes

In over 100-years of research and publication, NCPI has amassed an extensive library. The papers available here include our most referenced materials.

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Featured Papers

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Vitrified Clay Pipe Thru Steel Casing Procedure

The following procedure for “Installation of Carrier Pipe Within A Steel Casing” is taken from past projects, where this method produced successful installations.

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Pilot Tube Method of Guided Boring as the Conservative Option

The communities of Mission Bay and Pacific Beach, in San Diego, CA are much like many other ocean-front areas with high tourism, an expectation of uninterrupted services and high-water tables. However, the environmental regulations within the state of California present additional challenges. 


Guidelines For Controlled Low Strength Material (CLSM) Mix Design, Placement And Testing For Use As A Bedding Material For Vitrified Clay Pipe

Controlled Low Strength Material (CLSM) is used as a bedding material for Vitrified Clay Pipe to meet the requirements of ASTM C12 – Standard Practice for Installing Vitrified Clay Pipe, Section 6, Bedding and Encasement, and the National Clay Pipe Engineering Manual (2006), Chapter 4, Part II, Structural Design.
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Low-Pressure Air Test For Sanitary Sewers

The low pressure air test is the preferred method of testing pipe joints and sewer line installation. This test is used for line acceptance or leak location. A specific drop in air pressure within a pipe system over a specified length of time determines acceptance or failure of the line in question.

Sanitary Pipeline Pilot Project After 42-Years Of Service In Lima Ohio

The Vernon Heights Polyvinyl Chloride (PVC) gravity sanitary sewer was constructed in 1976 for Allen County, Lima, Ohio. This installation was a trial of PVC (SDR 35) as a new material in the system.

2014 Updates To ASTM C12 Final Paper ASCE Pipelines 2015

The ASTM standard C12 “Standard Practice for Installing Vitrified Clay Pipe Lines” gives recommended methods for installing vitrified clay pipe (VCP). C12 was significantly modified for the 2014 version (C12-14).

The New Chapter 12, NCPI Engineering Manual

Ceramics are among the most abrasion-resistant materials known.  As a ceramic, VCP is the most abrasion-resistant, commonly-used sanitary sewer pipe material.


The Evolution of Jointing Vitrified Clay Pipe

Advances made in the jointing of vitrified clay pipe during the last half century, illustrate the concern of the clay pipe industry to provide top quality jointing methods.  Prior to this, the lack of standards for joint integrity meant testing for infiltration and Exfiltration was seldom implemented.

Tech Notes

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More Technical Papers

Tips for Laying VCP

by NCPI – 09/23/2016

A brochure for tips on laying VCP with English and Spanish translations. 

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Pilot Tube Microtunneling Chosen in Omaha Nebraska for 585’, Single Drive with Depths Reaching 50’ to Preserve Sensitive Garden Area

by David Gill, Chris Koenig, Chris Cain, Kenton Moore and Tim Papstein – 04/04/2014

Omaha, NE, stretching along the Missouri River for 7 miles, is currently under a consent order with the Nebraska Department of Environmental Quality to improve the water quality in the Missouri River. The estimated construction cost of the program, including sewer separation is $1.7 billion dollars. One project defined by the program was a sewer separation project, which took place in a very sensitive setting, Omaha’s Lauritzen Gardens.

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Importance of Haunching

by Jeff Boschert, P.E., MASCE and Amster Howard, MASCE – 01/03/2014

Presented at ASCE Pipelines, 2014 – Testing on bedding practices that don’t include haunching reveal voids and call the assumption of uniform haunch support into question.

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CLSM as a Pipe Bedding

by Jeff Boschert, P.E. and John Butler – 01/08/2013

Presented at ASCE Pipelines, 2013 – CLSM as a structural bedding material for VCP. Optimal mixes, methodologies and resultant safety factors are discussed.

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Optimal CLSM Mix Design – As Developed by Means of Small Batch Testing

by NCPI – 01/06/2013

These tests were conducted to define the optimal mix for Controlled Low-Strength Material (CLSM) used in gravity sewer applications with vitrified clay pipe. Varying percentages of 3/8-inch coarse aggregate, accelerator and entrained air were tested. 

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Guidelines for Controlled Low Strength Material (CLSM) Mix Design, Placement and Testing for Use as a Bedding Material for Vitrified Clay Pipe

by NCPI – 01/04/2013

Controlled Low Strength Material (CLSM) is used as a bedding material for Vitrified Clay Pipe to meet the requirements of ASTM C12 – Standard Practice for Installing Vitrified Clay Pipe, Section 6, Bedding and Encasement, and the National Clay Pipe Engineering Manual (2006), Chapter 4, Part II, Structural Design. 

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Consideration for Flotation when CLSM is Used as a Bedding Material

by NCPI – 01/01/2013

No field installations using CLSM have resulted in flotation of clay pipe. CLSM is being successfully used as a bedding material for vitrified clay pipe. It simplifies the installation of pipe, reduces labor and inspection costs, allows for early backfill, is easy to place, and provides a 2.8 Load Factor.

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A Short Course in Pilot Tube Microtunneling

by David Gill – 01/01/2010

PTMT is generally used for new installation of small diameter gravity flow pipelines. These machines can operate out of a minimal diameter shaft and provide pinpoint accuracy through the use of a LED target viewed down the center of the pilot tubes with a theodolite and LCD monitor. The Pilot Tube Microtunneling (PTMT) method of pipeline installation can be used with pie outside diameters ranging from 4 to 48 inches. PTMT is a trenchless installation method for pipelines with grade and alignment precision to within 1/4 inch per 500 LF throughout the entire drive length. Due to this line and grade accuracy, this system can install product pipe by direct jacking without the use of casing. This method involves a three-step process starting with launch and reception pits strategically located to minimize surface disruption. 

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