This test is for the purpose of success in duplicating one previously accomplished and to allow potential end users to evaluate the process as it applies to their particular circumstance as well as to display to owners and engineers the benefits and difficulties involved in this type of work. Surface improvements and reconfiguration have necessitated the use of trenchless methods and while it seems clear-cut, trenchless installations regardless of their nature are not as perfect nor as free of unknown hazards as open cut procedures and there is no guarantee of absolute success. The repercussions of machine failure, encountering underground obstacles, changes in pipe material, and/or metal repair sections, can be many times more damaging than when met in an open cut situation.

Pipe: 18" I.D., 23" O.D., Reinforced Concrete Pipe, Class III
24" Corrugated Metal Pipe, 14 Gauge
Length: 18" RCP - 56'
24" CMP - 12' +/-

The pipe is encased (8" below, 12" on sides and top) with lean concrete, sand mix, to simulate compaction conditions usually encountered with pipe buried for many years.

The unknown aspect of the bedding strength presents a condition that would not normally be found, that being if the bedding strength is excessive, it will act as an encasement rather than a simulated soil condition. We do not propose that 100% of the reinforcing mesh will be shredded or pulverized, realizing that a portion will be left in the over-cut annular space along with pipe cuttings, bedding material, and drilling fluids. If perceived as an objectionable characteristic in the condition of “encasement”, the concern is alleviated when the “encasement” condition does not exist, that being one of scarring of the replacement pipe, because the sharp components of the shredded pipe would not be forcibly confined to the annular space, the result similar to but less likely damaging than that encountered with pipe bursting.

The reamer used for this test was made in our shop for use on a similar pipe condition in Kansas City, Missouri. The O.D. is 28" with a center cone set having an O.D. of 16". Reamers of this type, by their size and nature, are custom fabricated to accommodate the removal/replacement sizes undertaken. Consult Nowak Pipe Reaming, Inc., The Charles Machine Works, your local Ditch Witch dealer, INROCK, or other HHD accessory manufacturer for custom fabrication information and pricing.

The three PVC tubes are inspection portals for your viewing during the installation process. The viewing time for each will be pretty short, and since it will be necessary for the vacuum truck to have access, it will be crowded, so please allow others a little time to see what’s happening.

Thank you for your interest in the InneReam® process and a Special Welcome to our new friends from Magnolia Construction and JM Cable Corp.

RESULTS and CONCLUSIONS

Upon entry into the encased RCP the reamer wobbled violently, the roller cones not in uniform contact with the face of the pipe, but once cut into the pipe the reamer became stable. This condition should be remedied as much as possible by configuring the grade at the entrance point to provide as nearly as possible, uniform contact of the reamer with the pipe to prevent fracturing thus continuing the difficulty for a longer distance, and prevent possible damage to the reaming tool.

Once stabilized, the reamer progressed at a rate of 60+/- feet per hour. Noticing the apparent tendency to stall, the “winding up” and subsequent release of the drill stem, the drill operator was inquired of this. He replied that the drill had come directly from a project where it had worked under extreme conditions and he had some concerns for the drill stem and the ability of the jaws to restrain the stem when unscrewing the joints. Upon observing the difficulty in unscrewing the drill stems, his concerns were appreciated.

The observed pull back force was less than half of the machine’s (Ditch Witch 7020) potential, 20,000 lbs vs 70,000 lbs and the torque approximately half its’ potential, 5,000 ft/lbs vs 10,000 ft/lbs with the rotation speed approximately 90 RPM. A more powerful unit or a similar unit without the constraints cited above would have increased the installation rate substantially.

Cuttings were noticeably fine with no indication of “chunking” of the pipe or any large pieces of reinforcing wire left in the overcut annular space or in the debris flow. The reamer did in fact perform its function better than anticipated in cutting of the concrete pipe and reinforcing wire with no observable wear. Reamers of this type are extremely expensive and the absence of observable wear is an unexpected reward that translates into less expense for all concerned.

It is reasonable to assume that under normal conditions “chunking” of the pipe will likely occur because of deterioration, but it may also be assumed that the aggressive nature of this particular reamer style will successfully grind the large loose pieces as well as we have seen the pipe ground in this test. Mud flow was not considered for the purpose of debris removal, but rather to provide a coolant for the cutting teeth and a lubricant for the HDPE pipe. The fineness of the ground pipe particles as observed will provide for a smooth, continuous flow to an extraction point. On first use, it is prudent to verify mud calculations and anticipated flow by the use of an observation portal 30' +/- from the point of entry into the replaced line. Adjustments made at this point can prevent Although the reamer used did cut the CMP it did not perform sufficiently well enough to recommend its use. Until more testing of tooling and procedure is accomplished, Nowak Pipe Reaming, Inc. will not recommend replacement of CMP using the Pipe Reaming process.

As a result of this test and similar replacements, Nowak Pipe Reaming, Inc. is confident of success by licensees to replace Reinforced Concrete Pipe Class III who follow procedure, and use proper equipment and tooling. CLASS V Reinforced Concrete Pipe, or CLASS III that has substituted reinforcing bars, is not included in this recommendation.

Our Guests and Observers included:
Contractors from;
Baton Rouge, LA
Commerce City, CO;

City Officials from;
Wichita, Kansas
Lenexa, Kansas

Engineers from three firms in Wichita, KS

Representatives from The Charles Machine Works (Ditch Witch) Perry, OK and Wichita, KS