North American Special - Trenchless International
North American Special - Trenchless International North American Special - Trenchless International
north america April 2009 - Trenchless International HRX: heading across the harbour A record was recently set on the Virginia Natural Gas Hampton Roads Crossing (HRX) HDD bore. Project Manager Les Flora spoke with Trenchless International about the innovative and challenging project. The aim of the project is to support distribution company Virginia Natural Gas (VNG), a subsidiary of AGL resources. The project itself comprises 21 miles of 24 inch diameter pipeline, extending transmission gas facilities under Hampton Roads Harbour, Virginia. The harbour is one of the largest natural harbours in the world. The harbour is also home to the largest naval base in the world and has a significantly high degree of commercial maritime traffic. The crossing of the harbour itself includes four miles of pipeline from Newport News to Newport News. In addition the project involves an HDD crossing of the Elizabeth River. This crossing demanded a 7,300 feet (2,225 metres) HDD drive in 24 inch pipeline – a bore record. Project Scope Currently, the VNG distribution system is divided into two non-contiguous pipeline systems – southern and northern – due to the geography of the Hampton Roads harbour. On a peak day, each system is fed by a single gas supplier; Columbia Gas Transmission in the Southern system and Dominion Transmission in the Northern system, making them vulnerable to gas disruptions. This project will ensure reliability of supply and future availability. The project includes the construction of approximately three miles of onshore pipeline in Hampton, four miles of onshore pipeline in Newport News, four miles of onshore pipeline in Norfolk, and ten miles crossing the Hampton Roads Harbour. The project will also include upstream pipeline compression facilities in Hanover and Charles City Counties, and a city gate station at the termination point in Norfolk. Design and construction The marine construction project team included Weeks Marine, Mears Horizontal Directional Drilling and Bradford Brothers. Weeks Marine is the general contractor on the marine portion, providing all of the marine equipment and diver support. Mears and Weeks teamed up to complete the HDD with their pipeline subcontractor, Bradford Brothers. Crossing the harbour The harbour crossing consists of five separate HDDs ranging in length from 3,000 – 3,800 feet. Mr Flora said that Trenchless Technology was selected for a number of reasons. The two main drivers were the environmental permits and the US Army Corps permits required as the pipe path bisected an anchorage area. The Marine Resources Commission is very active in protecting the area. Alternative methods such as conventional dredging, laying pipe on the bottom or even jetting it in were considered. However, Mr Flora said that “because of the environmental impacts, or I should say, perceived environmental impacts, the Marine Resources Commission would not permit it. So we had to directionally drill under their biggest area of concern. “On the Army Corp side there is approximately 5,000 feet of pipe to go under an anchorage area. The anchorage space is so valuable to the maritime community that the decision was made to directionally drill this section of the pipeline.” Finally, a natural shipping channel is also a part of this crossing. Mr Flora said that the company was aware that this section would be directionally drilled in order to reach the depth that would be required under the channel. The depth of the channel is 15 metres with a design depth of 19 metres. The drill path was required to be a minimum of 6 metres under the design depth. Therefore the shipping channel drill was approximately 25 metres below the water. Mr Flora continued “Three of [the drives] are marine to marine drills so we’re drilling from a barge and the receiving rig is on another barge. “We’re building those pipe sections out on the end of Craney Island, which is basically a beach, out into the harbour and then towing those sections by tying them to tug boats. Towing them off the end of the island and floating them into place and then sinking them and then hooking them back to the drill rigs for the pull back.” Mr Flora said there is also another area requiring trenchless expertise. “We are doing a bunch of small directional drills, on the Upland piece of this project. We have 7 miles (11.2 km) of pipe on land in Newport news, and about 4 miles (6.4 km) in Norfolk. They are very heavily urban quarters, there are just not a lot of good places to put pipe, much less 24 inch pipe.” For example, for the first mile onshore of Newport News, the pipe was directionally drilled under a tidal wetland creek as there was not a less congested route for the pipe. This pipe was separated into two drills, each approximately 2,800 feet (853 metres). Mr Flora said that space was incredibly tight, “the pipe looked like a pretzel wrapped around a tree.” Mr Flora said that without Trenchless Technology the sections directionally drilled, in most cases, could not have been completed in an alternative method in a cost effective way. A challenging crossing The Elizabeth River crossing was one of the most ambitious and challenging parts of the project as this demanded the laying out of a string of pipe 7,300 ft long. Fortunately Craney island, a government owned area, is located right in the middle of the project. The island is a US Army Corps dredge disposal management area. The contractors had to share the very small island area with Army Corp Engineers and the associated traffic. Mr Flora explained that the Dominion University is located on the other side of the river where the pipe was to be pulled back. During the semester this area is filled with approximately 24,000 students. Therefore the team could only operate from 12 May until 20 August. Elizabeth River Crossing: pullback. Elizabeth River Crossing. Harbour Crossing: pull head with hose connections for pipe flooding. Elizabeth River Crossing: pullback. north america April 2009 - Trenchless International 62 63
“We had a very tight window to get the work done, which meant that had anything had delayed the project we’d have been stuck there in that parking lot and probably incurred some very high costs. “Fortunately, we made the time, in fact we got out 20 August around noon, and the University opened the next day and the students came back into the dorm.” Elizabeth River Crossing Length: 7,300 feet (2,225 metres) Diameter: 24 inches Pilot hole: 660,000 lb. drilling rig Pullback: 22 hours Community Consultation The project began in August 2006. In the initial months, VNG developed a communications plan and contacted regulatory agencies and elected officials at both a state and city level. The public watchdog groups were also included in the environmental issues encountered when planning the project. Mr Flora explained “We spent a lot of time with those folks, talking to them. They saw the benefits, especially in crossing the harbour. They were the first groups to really talk about drilling as opposed to dredging, to protect the environment. So we were looking at drilling all along from the beginning of that project.” Keep in touch with the hole world Free subscription to all Toronto No-Dig attendees north america Future The transmission network will increase the supply to up to 100,000 tonnes a day into the southern region and will also move another 25,000 decathons to Columbia Gas in Virginia to their account in Portsmouth. The HRX project is scheduled for completion by November 2009. Once operational, the gas pipeline will ensure a reliable supply well into the future for the communities of Virginia. April 2009 - Trenchless International Subscribe online by entering the code TND09 at 64
- Page 1 and 2: In this issue | Canada | USA | Japa
- Page 3 and 4: Dec Downey Istt Chairman Trenchless
- Page 5 and 6: EXECUTIVE DIRECTOR'S REPORT John He
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- Page 21 and 22: Risky business by Roderick Lovely a
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“We had a very tight window to get<br />
the work done, which meant that had<br />
anything had delayed the project we’d<br />
have been stuck there in that parking lot<br />
and probably incurred some very high<br />
costs.<br />
“Fortunately, we made the time, in fact<br />
we got out 20 August around noon, and<br />
the University opened the next day and<br />
the students came back into the dorm.”<br />
Elizabeth River Crossing<br />
Length: 7,300 feet (2,225 metres)<br />
Diameter: 24 inches<br />
Pilot hole: 660,000 lb. drilling rig<br />
Pullback: 22 hours<br />
Community Consultation<br />
The project began in August 2006.<br />
In the initial months, VNG developed<br />
a communications plan and contacted<br />
regulatory agencies and elected officials<br />
at both a state and city level. The public<br />
watchdog groups were also included in<br />
the environmental issues encountered<br />
when planning the project.<br />
Mr Flora explained “We spent a lot of<br />
time with those folks, talking to them.<br />
They saw the benefits, especially in<br />
crossing the harbour. They were the<br />
first groups to really talk about drilling<br />
as opposed to dredging, to protect the<br />
environment. So we were looking at drilling<br />
all along from the beginning of that<br />
project.”<br />
Keep in touch<br />
with the<br />
hole world<br />
Free subscription to all Toronto No-Dig attendees<br />
north america<br />
Future<br />
The transmission network will increase<br />
the supply to up to 100,000 tonnes a<br />
day into the southern region and will<br />
also move another 25,000 decathons to<br />
Columbia Gas in Virginia to their account<br />
in Portsmouth.<br />
The HRX project is scheduled for<br />
completion by November 2009. Once<br />
operational, the gas pipeline will ensure<br />
a reliable supply well into the future for<br />
the communities of Virginia.<br />
April 2009 - <strong>Trenchless</strong> <strong>International</strong><br />
Subscribe online by entering the code TND09 at<br />
64
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