St. Charles Parish, one of nine Louisiana parishes (counties) comprising the New Orleans metropolitan area, is bisected by the Mississippi River, which can complicate parish government services to its residents.
For example, to provide drinking water to homes and businesses on both sides of the river, the parish has for years operated two water districts, one on the East Bank and one on the West Bank, each with its own treatment plant.
For 40 years, the two districts were governed by individual boards of directors, but in 1989 their operations were combined under the St. Charles Parish Department of Waterworks. However, residents remained dependent for water from the plant on their side of the river. The East Bank plant is about five miles upriver from the West Bank facilities, and many West Bank communities actually are closer to the East Bank facility, but there was no way to get water across the river – a distance of approximately 2,755 feet. If for any reason one of the plant’s operations was interrupted, there was no way to transport water from the other plant across the river.
“The idea of putting a water line under the river to connect the two systems was considered 20 years ago, but it was determined to be too expensive,” said Robert Brou, waterworks department director. “Ideally, the two systems should be connected, but no cost effective solution had been found to do so.”
As it had in so many other ways, Hurricane Katrina impacted St. Charles Parish’s water dilemma.
“Katrina hit us hard,” said Brou, “but we recovered fairly quickly. We never lost water pressure and made repairs fast. Jefferson, Orleans and other parishes sustained much more damage, and we had a lot of people relocate to our parish. We had a huge spike in population and water consumption, and the East Bank plant already was operating at near capacity. By the end of 2005 and into 2006, we were really beginning to feel the impact and had no long term solution in place.”
To move forward, Brou said, plans for a two pronged solution were developed:
- Construction of a new East Bank treatment plant; and
- Construction of two 24 inch water mains under the Mississippi River.
The river crossings were submitted to the U.S. Corps of Engineers as emergency projects in order to speed the permitting process and expedite construction, said Brou. Both crossings were made by horizontal directional drilling. The first crossing was completed just before Christmas in 2007 and is in operation. Pipe pullback for the second crossing was completed on Feb. 28, 2009.
Owner of the projects was the St. Charles Parish Department of Waterworks; the consulting engineering firm was Shread Kuyrkendall & Associates, Baton Rouge; and the contractor for both river bores was Ranger Field Services, Broussard, LA, a Quanta Services company.
A Vermeer 330×500 directional drilling rig was used to make both crossings. The machine develops 330,000 pounds of pullback, maximum spindle speeds of 50,000 pounds and speeds to 88 rpm.
The second crossing was 3,000 feet long at a maximum depth of 165 feet and was completed on the last day of February after 22 work days, said Boyd Simon, P.E., Ranger Field Services division manager.
Set up for the installation was near the town of Luling and included clearing trees for a 150 by 300 foot area on the entry (West Bank) side of the river and a 150 by 200 foot area on the opposite side at the exit point in the town of Destrehan. Four hundred twenty five yards of fill dirt was hauled to the exit area to provide firmer ground.
The 8 inch pilot hole was launched from the surface and required three days, averaging 1,000 feet per day. The maximum 165 foot depth was achieved at the 1,007 feet point of the bore. For the pilot hole, an 8 inch mill tooth bit was used. One backreaming pass was made with a 24 inch fly cutter reamer and a second with a 36 inch fly cutter tool. Backreaming required 14 days with pullback completed in eight hours.
The first bore was completed in December 2007 and new line was fully operational in December 2008.
A 200 by 300 foot launch area was prepared and 650 yards of fill brought in for the drill rig set up. Simon said the 3,300 foot long bore path contained a compound curve of 6 degrees to the left and 9 degrees to the right. This was necessary to stay within boundaries of acquired right of way.
The 8 inch pilot hole, also surface launched, required four and a half days, averaging 733 feet per day. Maximum depth of 150 feet was achieved at the 901 foot mark. The same type of bits and backreamers as used on the second installations were used on this installation. Backreaming was completed in 16 days with one backreaming pass made with each size reamer. Pullback was completed in 10 hours.
Sixty six joints of pipe were fused along State Highway 3160 which, along with State Highway 18, was closed for a short period during construction.
Soil conditions on both bores were sandy clay. A Tensor magnetic steering probe and Tru Tracker Trugyde software were used to guide the pilot bores. J M Manufacturing provided the 24 inch diameter SDR9 HDPE pipe for both installations.
Every long river crossing has its own unique issues, and Simon said there were several that affected both installations.
“We were working inside U.S. Army Corps of Engineers levee areas, and to bring in equipment required temporary access roads over the levees,” he explained. “Roads were constructed in accordance with Corps permits. Timing of the projects was closely monitored due to the required river stage – work could only be performed once the river stage was below 11 feet NGVD (National Geodetic Vertical Datum) in elevation.”
The most challenging task on both projects was steering the pilot bore, said Simon.
“Drill entry and exit locations were within only 100 feet of the water’s edge of the Mississippi River,” he continued. “This limited options available when choosing an azimuth for crossing the river. Adding to this complication was continued boat traffic in the river. As large tugs and barges passed in the waterway, drilling operations would cease due to the magnetic interference to the steering tool. For the second crossing, 11 barges were parked near the exit spot, which disrupted the azimuth as the steering tool crossed this location.”
Even so, pilot bores were completed with extreme accuracy.
“The exit location for the first crossing was 11 inches from the exit stake,” Simon said. “And for the second crossing the drill head surfaced only four inches from the target stake. The expertise of Survey Engineer Daniel Dodgen of Ranger played a large role in the success of both crossings. Drill operator was Jody Utz.”
Because of the length of both crossings and limited space for pipe fusion, road closures were required on both projects. Area newspapers and television stations carried notices in advance of the closings, and the St. Charles Parish police implemented procedures to close roads and divert traffic as necessary.
Simon said no under river crossing of the Mississippi is simple, and despite the complexity of the two St. Charles crossings and the various complications encountered, each was completed ahead of schedule because of the hard work and cooperation of numerous individuals and organizations, including Barry Nailing, Ranger supervisor; Waterworks Director Robert Brou and Waterworks personnel; David Einsel, P.E., of Shread Kuyrkendall; Jay Roberts of Water & Sewer Products, Bridge City, LA; and John Delong, Jim Ryan and Tom Lytle, Vermeer Equipment of Texas.
Ranger Field Services specializes in underground installations of pipe and conduits beneath waterways, highways, congested areas and environmentally sensitive environments.
Brou said the under river water lines provide many benefits to St. Charles Parish and its population.
“The more we look at the projects, the more benefits we see,” said Brou. “They provide increased capacity on both sides of the river with the ability to direct water flow in either direction. If we have a power failure or problem with a plant on one side of the river, we can draw water from the other, and we can also shut down a plant for maintenance and not interrupt water service.”
The Mississippi River is the water supply for St. Charles Parish, and oil spills in the past have caused problems.
“Intakes for the East and West Banks are about five miles apart,” Brou said, “and there have been instances where spills have affected water supplies on one side, but not the other. Being able to move water under the river will make it much easier in the event such incidents occur in the future. And as soon as the second crossing is on line, the C Plant on the East Bank can be taken off line to make much needed repairs.
“With both lines operational and everything running smoothly, communities on both sides and either end of the parish will have better water flow, better pressure and as a result, better fire protection,” Brou concluded.
FOR MORE INFORMATION:
Ranger Field Services,(337) 837-5447, www.rangerdirectional.com
Shread Kuyrkendall & Associates, (225) 296-1335, www.shreadkuyrkendall.com
Vermeer Equipment of TX, (800) 777 5128, www.vermeertexas.com
Vermeer Corp., (888) 837-6337, www.vermeer.com