The drought of 2005–06 is on record as being one of the worst in North Texas' recorded history. Community leaders throughout the affected area labored with decisions of how to allocate an ever-shrinking supply of water.
Water has played an ironic role in the history of Corsicana, a small city located about 50 miles south of Dallas. In 1884, the city hired a water well driller. But instead of hitting water, oil spurted from the well. It was the first oil field discovered west of the Mississippi River. The city fathers were so unhappy they refused to pay the contractor. Soon after, Corsicana became the first Texas oil boomtown.
As of early 2007, the current city leaders had a much more serious reason to be unhappy with the water situation — they were running out of it.
The city's two water sources are Navarro Mills Lake, a reservoir southwest of the city and Lake Halbert, a small reservoir near the water treatment plant. As late as Jan. 2007, Navarro Mills water level had dropped more than 8 feet from normal levels, 3 feet below "Moderate — restricted use" levels and less than 2 feet from "Severe — no outdoor water use" levels.
In October 2006, when the project was completed, the drought had surpassed the year-and-a-half mark, and city officials were forced to figure out a way to get water to the 25,000 residents — and fast. The answer was to pipe the water from the still-plentiful Richland-Chambers Reservoir, southeast of the city.
Because of its immediate availability and low total cost of installation, smoothwall high-density polyethylene (HDPE) pipe was chosen for the emergency pipeline.
"Due to the railroad lines and the restricted right of ways on this project, HDPE was really the only pipe that could be used for this project," said Corsicana Environmental Services Manager Larry Murray. "We had just 3 feet or 4 feet around the pipeline to work with. Other pipes would have needed much bigger right of ways for the trucks, welders, etc."
Murray added that the HDPE pipe has a high recoverable market value if they should ever decide to sell it when the emergency line is no longer needed. But even better, the pipe could be reused for another pipe project elsewhere in the city. A permanent line will be installed after Oct. 2008.
Since Corsicana has some water rights to the water in Richland Chambers, the city struck a deal with Tarrant County Water District (TCWD) to tap into the district's transmission line to supply water to Lake Halbert due to the drought conditions.
The 16-inch polyethylene line ran from the TCWD transmission line to an existing city line leading to Lake Halbert. The line was mostly laid above grade with five directional bores — two under highways, two under county roads and one creek crossing.
The line is delivering 4 million gallons of water per day to the city, which meets about half of the community's daily needs.
"When we got the call, we were told the city was about three weeks away from the severe drought category," said Tom Fraser of Fraser Mining, a member of the Plastics Pipe Institute (PPI), a trade association headquartered in Irving. "We were able to install an average of about 2,500 feet of pipe per day."
The job was started on October 2, 2006, and completed on October 18, 2006. About 26,000 linear feet of pipe was installed utilizing a four-man crew and three fusion machines. Fusion joining creates a leak-free, monolithic pipe string and also eliminates the need for restraining devices on joints and fittings.
"With the purpose of this project being to deliver water to a drought-stricken community, any water leak would be totally unacceptable," Fraser emphasized.
Fraser said the biggest challenges were maneuvering through the lower areas of a flood plain, the creek crossings and the underground borings. The shortage of time and the shortage of right of ways meant that cooperation with the city was crucial.
"The city had used PE pipe in directional drilling and pipe bursting projects in the past," Fraser said. "Because it's a temporary line, we knew most of the line would be above grade.
"But since the joints were leak free, and the pipe itself is black, we were not worried about leaks or UV degradation. And the flexibility of the pipe lends itself perfectly to the underground installation sections."
Corsicana project manager Jerry Yeats of Fraser Mining used directional drilling techniques to make the 250-foot creek crossing from Richland-Chambers to Lake Halbert.
"HDPE makes it easy to pull a sleeve for your underground bores then pull the pipe right through that," Yeats said. "In environmentally sensitive areas, this installation technique is the best thing going. Plus, we didn't know exactly what 'temporary' meant, so we needed a pipe that would last a long time and not be susceptible to corrosion."
The other four bores were dug conventionally. Yeats said the site prep and remediation was limited to those bores and the large hole required at the tie end. The entry at the source required an excavator and bulldozer to access the concrete tapping sleeve.
He added that the cleanup required for the trenchless bore across the creek is about 1/10th that of the traditional bores.
"Polyethylene pipe is ideally suited for these demanding installations because of its continuous, jointless fused system and because of its flexibility, corrosion resistance and seismic resistance," says Camille George Rubeiz, P.E., director of engineering at PPI.