Boring - Trenchless International

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A 20-inch steel pipe is elevated by cranes for pullback and the transition of product pipe back into the opened hole. Because the pipe string-out and pullback was in a marshy area, a trench was excavated, which caused ground water to fill in and provide a pullback floatation system in lieu of a typical pipe roller system. A crane is floated on a barge as bundled pipeline (12 inch/4 inch) is floated across a main canal during pipe pullback operations. The pipe is supported by the crane and styrofoam floats as it is being smoothly pulled back through the earthen hole. North america April 2010 - Trenchless International After the hurricane – rebuilding New Orleans In the aftermath of Hurricane Katrina, more stringent requirements resulted in the innovative use of Trenchless Technology for the installation of underground infrastructure. Here we learn about a successful project involving two crossings near levees. Think of levees and you think of the catastrophic consequences of their failure when Hurricane Katrina came ashore and rocked New Orleans in August 2005. Over four years have passed since more than 80 per cent of metro New Orleans was left underwater when 53 of the levees protecting the city failed. But while the city has long since picked up the pieces and returned to its vibrant self, the message from the disaster has remained clear: bolstering and preserving the surrounding levee system is of the highest priority. The images captured in the aftermath of Hurricane Katrina resonate with people around the world. For the underground construction industry, those disastrous results left a lasting impression, forever changing the methods and procedures associated with crossing a levee. Michels Directional Crossings, a division of Brownsville, Wisconsin-based Michels Corporation, recently dealt with this firsthand after being awarded a contract by Chevron for work near New Orleans that began in September 2009. Michels signed on to complete two separate crossings within two miles of each other, both running beneath the Mississippi River and the extremely important protective levee system. The first crossing was the 20-inch Fourchon Pipeline, which consisted of 5,087 feet of steel pipe running through silts, sands and clay. The second crossing, the 4,708 foot Buras Bundle, ran through the same soil conditions and consisted of one 12 inch and one 4 inch steel pipe. Engineering challenges In the aftermath of Hurricane Katrina, the US Army Corps of Engineers (USACE) adopted more stringent requirements for construction around levees in hopes of better preserving their protective qualities. For Michels and Chevron, this meant meeting the USACE-established “Guidelines for Installing Pipeline by Nearsurface Directional Drilling under Levees,” which required that: “…the entry or exit points, when located land-side of a levee, should be set back sufficiently from the land side toe of the levee such that (a) the pipeline reaches its horizontal level (max depth), and/or (b) the pipeline contacts the substratum sands or some other significant horizon, at least 300-feet land side of the levee toe.” To discuss the plans to meet these requirements, Chevron requested that Michels meet directly with the USACE in New Orleans several months prior to the project start date. Acting as a third-party engineer for Chevron, Geo-Engineers provided Annular Pressure Curve data based on representative soils and proposed drill geometry, which are just a few variables used for estimating hydraulic fracture potential. With this data, Geo-Engineers recommended that downhole mud pressure be limited to 92.7 psi in order to provide the required 1.5 safety factor against fracture within 300 feet on either side of the levee toe (critical monitoring zone). Armed with this information, Michels developed and presented a comprehensive drill plan that reflected many innovative mitigative measures to reduce annular pressure. While this consisted of many specialised tactics, one particular method involved performing a pilot hole intersect just beyond the 700 foot long critical levee monitoring zone to reduce downhole pressures. Annular Pressure Monitoring was also conducted through this zone during both pilot hole drilling and reaming operations, and the depth of cover beneath the levee was also maximised to minimise fracture potential. The established target intersect zone was 1,800 to 2,200 feet from the levee side entry point. Construction challenges Serving as project manager for Chevron, Ralph Radomski oversaw the drilling, pipe stringing and marine operations conducted by the team of contractors. To support Michels’ drilling operations, Chevron hired a local contractor, Sunland, who are familiar with directional drilling procedures and have extensive experience in local marine construction. Sunland performed pipe string-out and welding operations for both crossings, and also provided marine support for the HDD operations. This included barging Michels’ resources to the exit sides and excavating a temporary false ditch for floating the pipe through a marsh area before finding suitable water to float the remaining section. The first section of product pipe was floated into the false ditch up to the main canal, and the remaining pipe string was staged in a tributary on the other side of the canal, readied for attachment to the first string. Both pipe strings were sunk to the bottom and tied off for protection of the coating. Once pullback operations were initiated, the main canal was blocked off and the two pieces were dewatered and welded into one string. They were then floated on top of the water for the duration of pullback. With the pieces in place and Tom Breunig and Ray Viator overseeing the project as managers for Michels, Michels Project Manager Louis Barber and drillers Paul Krings, Jeff Nehmer and Cale Mullenix went to work. The 20 inch crossing was conducted first, with the pilot hole started in late September. During vital drilling operations, the flood stage for the Mississippi River reached critical levels above eleven feet, which was the established flood level at the location. Because of this, the USACE criteria required Michels to shut down all drilling operations underneath the levee on 21 October. Hurricane Ida added more water to the mess when it bullied its way ashore on 10 November, and drilling operations were unable to continue until 23 November. The brackish water carried from the Gulf of Mexico flooded the drill site equipment and washed out the access roads. To make matters worse, the floodwaters also brought in an abundance of dangerous reptiles, including snakes. Prior to re-mobilisation of the entire crew, it took a full week for mechanics to change out oil, fuel, filters and electric motors for all engines onsite, and for repairs to be made to the access roads. Once the repairs and maintenance were complete, however, work on the crossing went off without a hitch. The crossing was designed to be 190 feet deep at the levee and 68 feet deep at the lowest point of the Mississippi River, and it was executed to perfection by the two drill rigs performing the pilot hole intersect. The crossing, which Michels monitored for annular pressure throughout pilot hole drilling and reaming operations, was completed by mid-December. With that difficult stretch out of the way, Michels began drilling for the 12 inch and 4 inch bundled crossing in the first week of January. With the co-operation of the weather this time around, drilling and reaming operations endured only minor difficulties in maintaining the targeted pressure beneath the levee. This was mitigated by adding casing and thinning out drill fluids at various stages of the operation. Once pressure was reduced to acceptable levels, Michels was able to successfully complete the drilling and reaming operations for the bundle, which was 180 feet deep at the levee and 60 feet deep at the lowest point of the Mississippi River. However, during pipe pullback, it was discovered that a portion of the 4 inch pipe was bent and in need of repairs. Pullback operations were temporarily delayed while the repair was made. Once repairs were made and X-ray, testing and coating was conducted, pullback on the crossing was complete by the end of January. Summary With the devastation wrought by Hurricane Katrina still fresh in many minds, any work on any levee near New Orleans is a sensitive endeavour with a lot of eyes watching. But thanks to close monitoring and the implementation of specialised pressure reducing methods, Michels was able to successfully install both crossings within the parameters set forth by the USACE and protect the levee – and therefore the city that has been billed as “The Big Easy” – from any adverse impacts. North america April 2010 - Trenchless International 34 35
Record breaking crossing in South Carolina The completion of another record breaking pipe installation in the US, this time at Parris Island, a marine training base in Beaufort, South Carolina, marks a series of successful and lengthy crossings of Fusible PVC pipe. Peace River HDD pull. North america April 2010 - Trenchless International Beaufort Jasper Water & Sewer Authority (BJWSA) contracted Mears Group, Inc. to horizontally directional drill two crossings, 6,400 feet of 16 inch DR 18 FPVC and 600 feet of 16 inch DR 21 FPVC under Archers Creek and Malecon Drive, respectively. Underground Solutions, Inc. (UGSI) supplied and fused the PVC (FPVC®) product pipe for this project. These installations are part of a project to divert the Parris Island wastewater flows to a BJWSA regional facility. The military base, Marine Corps Recruit Depot, trains about 17,000 recruits each year. BJWSA had previous experience with both Mears Group and UGSI during installation of 5,120 feet of 10 inch FPVC in 2008 to deliver reuse water to the Secession Golf Course on Lady’s Island. For two years, that stood as the record breaking crossing in a single pull using thermoplastic pipe. The first crossing of this most current project is the longest installation of PVC, with a drilled length of 6,400 feet. Installing the crossing from Jericho Island to Little Horse Island, the Mears’ crew drilled under tidal marshland on either side of Archers Creek. Mears utilised their 500,000 pound rig on the entry side at Jericho Island. They set up their 140,000 pound rig at the exit side of the crossing at Little Horse Island to assist in the pre-reaming operations. Mears used a jet sub with a 9 7/8 inch bit during the pilot hole drilling. Drilling through clays, cemented sands, shells and gravel took careful steering. During pre-reaming, Mears opened the hole in three stages starting off with an 18 inch hole opener, then 26 inches, and finally 34 inches. Before attempting to install the pipeline in the drilled crossing a barrel reamer was used to swab the hole. Because of the space restrictions and a requirement to keep traffic flowing on a busy road on the military base until the last minute, two prefabricated pipeline strings had to be fused together the day before the pullback. Down hole pressures and pull force were monitored carefully throughout the 20 hour installation period. For this project with known conditions and confidence in the experience of the HDD contractor, UGSI allowed a maximum pulling load of 175,000 pounds on the pipe – in practice the maximum tensile load applied at the drilling rig was only 83,000 pounds. The second crossing was across Mears’ 500,000 pound rig on the entry side of the project. Malecon Drive, which is the main road on Parris Island. During the 600 feet crossing, soft sands were encountered during drilling. Mears, using its 140,000 pound rig, pulled the FPVC pipe into place within two hours. The two drilled crossings are being connected in a conventional manner with restrained MJ fittings. Horizontal directional drilling with FPVC has become an economical approach for installing pipelines. PVC has a high strength to weight ratio, limited stretch under long duration loading, and corrosion resistance. Mears and UGSI have partnered together on many projects and successfully set record breaking crossings. The installation on Parris Island marks yet another record in length. Aerial view of the FPVC pipe strung along military housing. Peace River HDD intersect project by Dale Larison P.Eng, Engineering Co-ordinator, Engineering Technology Inc. TransCanada Pipelines’ North Central Corridor Project presented an exciting opportunity to push the boundaries of horizontal directional drilling in Canada. Near the town of Manning in northwestern Alberta a 42 inch natural gas pipeline had to cross the Peace River. The Peace River horizontal directional drilling (HDD) called for a 1,110 metre horizontal directional drill opened to a final ream diameter of 54 inches to allow for the installation of the 42 inch pipeline pullback section. The principal challenges faced by the crossing project were a limited construction season due to the need for frozen access roads and deep surface gravels at the crossing location. The general contractor was Louisburg Pipeline while Engineering Technology Inc. (Entec) provided engineering services and Direct Horizontal Drilling was the HDD contractor on the crossing. Engineering design and geotechnical investigation During the design phase of the project, existing geophysical and geotechnical Under the Peace River Justin Hedemann from HDD contractor Direct Horizontal Drilling spoke to Trenchless International about the North Central Corridor (NCC) for the Trans Canada Pipeline. There were three large drills on the NCC pipeline. 1. Peace River Intersect – 1,107 metres 2. Little Cadotte – 701 metres 3. Loon River – 635 metres Peace River and Cadotte were completed in 2008–09 and Loon river in 2010. Mr Hedemann said that one of the biggest challenges was gravelly ground condition. This necessitated the installation of large casing barrel sizes, which ranged as high as 84 inches in diameter, before the pilot bore could be drilled. Direct Horizontal used the telescoping method to case through the gravel layer. “Also the Peace River is over 600 metres wide, which did not allow for surface navigation ‘Paratrack II’ over that span. Instead the earth’s magnetics were used.” Direct Horizontal used their 1.1 million pound American Augers rig and a 160,000 pound American Augers rig to complete the pilot bore. The pullback required only 200,000 lbs of force, considering that the product line weighed approximately 1 million lbs the ease of the pull is accredited to the clean hole and Direct’s in house buoyancy design and execution team. gas April 2010 - Trenchless International 36 37
Page 1: In this issue | Colombia | South Af
Page 4 and 5: Issue 7 - April 2010 Great Southern
Page 6 and 7: World wrap New Orleans rebuilding i
Page 8 and 9: Largest CIPP project in Ireland CIP
Page 10 and 11: Colombian Society digs deep ISTT ne
Page 12 and 13: istt news April 2010 - Trenchless I
Page 14 and 15: Underground in North America North
Page 16 and 17: NASTT celebrates 20 years by Chris
Page 18 and 19: North america April 2010 - Trenchle
Page 22 and 23: gas April 2010 - Trenchless Interna
Page 24 and 25: DN150 liner installed and reverted.
Page 26 and 27: projetcs April 2010 - Trenchless In
Page 28 and 29: Pipe cleaning April 2010 - Trenchle
Page 30 and 31: Robotics April 2010 - Trenchless In
Page 32 and 33: Chemically restoring pipeline posit
Page 34 and 35: the international society for trenc
Page 36: Get your hands dirty... Enjoy Austr

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