Stripes and Pipes

Leavenworth AerialAs the oldest city in Kansas, Leavenworth is full of history ? in particular, American military history. Situated on the Missouri River about 25 miles northwest of Kansas City, Mo., the city is home to Fort Leavenworth, the oldest active U.S. Army post west of Washington, D.C., built in 1827.

The fort houses the Military Corrections Complex, which comprises the U.S. Disciplinary Barracks, sometimes abbreviated USDB, or called simply, Leavenworth. The USDB is the only maximum security prison of the U.S. Department of Defense and has been operated in Leavenworth, since 1875 ? 20 years after the city was incorporated.?

Similar to these military facilities, Leavenworth?s infrastructure ? specifically its water pipes ? has also been in use for more than a century. With aging infrastructure failing at a rapid rate, it?s no surprise that old cities such as Leavenworth might be at a greater risk, and in recent years, the city?s water department has been busy developing a replacement plan for many of its pipe networks.

While the city has taken a proactive approach to the rehabilitation and replacement of water lines, Leavenworth exemplifies a unique case study in which many pipes in the ground were found to be in good working condition, some of which were determined to be well over 100 years old. The city has also implemented trenchless technologies such as pipe bursting, of which the city does in-house, as well as horizontal directional drilling for the replacement of water lines. The water department was also forced to get creative in repairing a transmission main that was severely damaged when the Missouri River experienced one of the worst floods in history two years ago.

Water pipe likely from mid-1800'sReplacement Program & 100-Year-Old Cast Iron
The City of Leavenworth has about 180 total miles of transmission lines, water mains and service lines. About half of that pipe will likely need to be replaced over the next 20 years, according to John Kaufman, general manager of the Leavenworth Water Department, which serves about 50,000 people.

Since the 1990s, the water department has consistently evaluated and replaced water lines, but in 2005 it began a more proactive makeover of the system, replacing mainly cast iron pipe with high density polyethylene (HDPE) pipe. Kaufman says according to very accurate records kept by the city, much of the cast iron pipe that has been replaced was originally installed in 1882.

?The cast iron pipe was great pipe and [in the late-1800s] it was the technology of the day,? Kaufman said. ?When it was installed, people didn?t understand the importance of bedding the pipe in sand, and they certainly didn?t have polywrap in 1882 either. In general, the older large diameter cast iron pipe is still in pretty good shape.?

In terms of pipe size, the cast iron pipe was anywhere from 2 to 18 in. in diameter. The city also has some ductile iron pipe in the ground as big as 24-in. diameter, but the cast iron pipe seemed to have the most longevity, with much of it still in use.

?Last year, we cut into a 16-in. line that was installed in about 1909,? he said. ?It was actually bedded in coal, and it was in almost mint condition. The inside looked like new and the outside was just slightly pitted.? Kaufman attributed several factors to the pipe?s longevity, noting that it was well drained, had little standing water around it and was sand-cast pipe rather than pit cast and had different metallurgy.?

On a separate occasion, the water department discovered two pipes that are part of a network of large diameter transmission lines near its northern water treatment plant that were later determined to be recycled material from the civil war era. The treatment plant manager has old records of where materials originated from, and the transmission lines were projected to be used as early as the 1860s.??

Kaufman said once in a while, the city will dig up wooden pipes while excavating areas for new projects. The city once dug up 4-ft long, 3-in. inside diameter wooden water pipe that was determined to be used as a fire line and was excavated from Leavenworth?s old downtown area.

?It probably belongs in a museum somewhere,? he said. ?But it has some historical value, so we want to preserve it.?

Use of HDPE Pipe & Trenchless Applications
Temporary line from well  field to transmission lineSince 2005, Leavenworth has increased its use of plastic pipe, and in particular, its use of HDPE in the last couple years. The water department now uses mainly HDPE pipe to replace cast and ductile iron mains after getting the idea from a gas company in Kansas. ?We work closely with the gas utility and our guys started asking questions about HDPE to replace our ductile iron mains,? he said. ?One thing led to another and we decided to try it out.

?One thing that was neat about the HDPE is that we used it temporarily in some areas, and then we could cut it up and use it in different areas if we need to and reuse it elsewhere for a permanent installation. It?s flexible, durable pipe and it worked great and performed quite well.?

Kaufman said the applicability of HDPE pipe is especially useful in horizontal directional drilling and pipe bursting and the city has begun to utilize trenchless methods in Leavenworth?s downtown area in recent years.

?In an older city like Leavenworth, we have a lot of old streets, buildings and infrastructure,? he said. ?Digging up a street to replace a line didn?t seem real attractive, and directional boring was a better alternative at the time.?

The city is currently replacing 1,000 ft of 6-in ductile iron pipe with 8-in. HDPE using pipe bursting, which the city does itself, using a TT Technologies 800G Grundoburst machine the city recently purchased.??? ?
The water department has also used PVC pipe in certain applications, namely transmission lines.? According to Kaufman, PVC pipe works well for the city in some situations because it has a conventional ductile iron pipe size to it, and generally uses C-900 PVC and C-905 for fusible PVC.

?What we use depends on site conditions, what we need and price,? Kaufman said in reference to the city?s pipe materials. ?But we are flexible when it comes to pipe. We keep our options open, it?s all part of our toolbox.?

Soil conditions are another major consideration when undertaking pipe replacement projects, determining pipe materials and particularly when using trenchless techniques, such as directional drilling. In Leavenworth, soil classifications, in general, include a lot of lean and fat clay, according to Kaufman. This type of clay soil ? essentially clay soil with high moisture content ? can become rather corrosive.

?We established a requirement here in the city, where if we have a soil condition, where: 1) we have a shallow water table; and 2) we have a liquid limit of higher than 50 percent, we will not use anything but plastic pipe.? ?

2011 Missouri River Flood
In 2011, the upper basin of the Missouri River ? the longest river in the United States ? flooded due to record-high reservoir releases in response to excessive snow pack in the upper reaches of the Missouri River basin and record rainfall in Wyoming, Montana and the Dakotas. The flooding impacted areas along the Missouri River from Sioux City, Iowa, to beyond Kansas City, Mo., from late May until mid-September.

In Leavenworth, it was determined to be the second worst flooding in the city?s history. The flooding damaged the well field access road and took out a 24-in. ductile iron transmission line from the well field to the south treatment plant after the levee breached. The excessive water flow dug a channel 60 ft deep and about 1,000 ft wide, collapsing the water line.

Looking to avoid a similar situation that occurred in 1993, the water department designed and constructed emergency backup pumping systems for both of its water treatment plants. They then ran a temporary pipe from the well field to the transmission line to bypass the broken section with two strings of 8-in. HDPE pipe. ?
?So we kept our well field pumping water to our treatment plant using temporary bypass, comprised of two parallel lines of HDPE pipe. We didn?t have our full pumping capacity, but the two 8-in. lines were enough to meet our demands for those plants. We operated off of that for a long time.?

The city wasn?t without water for one second.?

?We kept it going. Our guys were out there working day and night and we had no water restrictions,? Kaufman said.

The response to the 2011 flood required the water department to work quickly and creatively, and the proactive approach clearly prevented a severe water shortage, especially considering the fact that so many entities are dependent on Leavenworth for water. The ability of the LWD to efficiently solve the problem is a testament to the wide array of work the city has taken on in recent years.

Andrew Farr is assistant editor of UIM. ?

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