History repeats itself: flume problems are memories for engineer

Retired engineer Rex Northcutt looks over photos of the work he supervised 46 years ago when Shelbyville's underground flood control system collapsed. (T-G Photo by Brian Mosely) [Click to enlarge] [Order this photo]

"These photos really bring back memories."

If you think that dealing with 200 feet of a collapsed storm water flume is a problem, try coping with what engineer Rex Northcutt faced in 1963 -- 2,300 feet of ruined steel lying underground.

Today, Shelbyville officials are dealing with a repeat of exactly what happened 46 years ago -- a damaged flume and a lot of questions surrounding the cause.

Over the past two weeks, Northcutt has returned to the job that brought him to Shelbyville in the first place. He's been assisting the city's public works department in marking where the flume is on the surface, so that workers will know where, and where not, to dig.

Fortunately, the damage today is nowhere near as extensive as it was in 1963, but Northcutt said that a lot of work will need to be done to correct the present dilemma.

"Enormous" damage

Readers of the Times-Gazette on Monday, July 15, 1963 were confronted with a photo of Bill Hill's car trapped in a section of a sunken Lane Parkway and an image of the damaged flume that looks nearly identical to photos taken last week of the underground structure.

At about 11 p.m. on Saturday, July 13, the underground flume "creased" -- bowing up from the bottom and disrupting water service in Shelbyville after eight and 12-inch water mains burst, as well as damaging sanitary sewer lines.

"Though no official estimates have been made, the amount of damage has been described by some as 'enormous,'" the T-G read.

Rain had fallen in amounts equal to what the region has experienced over the past few weeks, which Northcutt remembers as totalling eight inches.

The collapse ran from "near the intersection of North Brittain and Madison Sts. some 2,300 feet to just beyond where the railroad tracks cross the tube near the dike," the T-G reported at the time.

With workers laboring through the night to restore water service, lines were bypassed. However, the power system manager at the time, Theron Bracey, Jr., said that "other mains were liable to break at any time."

Muddy water was reported coming through pipes in some parts of Shelbyville and Bracey said that damage to water and sewer lines was "extensive."

But cars were also having narrow escapes as parts of North Main Street and Lane Parkway collapsed where the flume ran underneath. Two cars required a tow truck to remove them from the collapsed roads.

The speculation as to the cause in 1963 is pretty much the same as it is today -- water entered the region under the flume, and the flume creased upwards.

Flood control

Northcutt was 24 years old in 1963, and had already gained experience as an engineer at AEDC and working on the construction of Interstate 24 on Monteagle Mountain.

He worked as project engineer for Oman Construction on the flume, which was part of the massive $2.2 million Big Springs Urban Renewal Project, paid for with a federal grant, which included the flume, flood gates, pumps and streets.

The cost of the flume at that time was around $200,000, but in today's dollars, the entire $2.2 million project would equal $50 to 60 million.

ARMCO was the subcontractor that produced the pipe for Oman. The original engineers on the project were Paxton and Alexander; Northcutt called their work "a good design, a very complicated drainage design."

Northcutt said Shelbyville's forefathers at the time "had a lot of foresight" to get the federal grant for the project, which he called "exceptional for this size of a town that Shelbyville was."

The money not only paid for needed flood control, but also for public housing that still stands today in the center of Shelbyville. Before that, businesses and homes in that area would be inundated whenever heavy rains fell.

"This is how they qualified to get this urban renewal," Northcutt said.

The first collapse

The flume itself was laid along "an old creek/ditch" completely made up of rock that had to be blasted.

Northcutt explained that the day before the flume collapsed in 1963, the final tube had been laid down and ARMCO had just put in the final pieces of the flume at the inlet structure located at the corner of Madison and North Brittain.

About four feet of fill was put on the intake, however, a concrete collar had not yet been installed at the entrance of the inlet and workers had even left a bulldozer sitting on the top of the flume overnight.

"But when all of that rain came down ... and all that drainage, there was a lot of water coming," Northcutt said. It hit about 18 inches of cushioned rock that was underneath the flume "and started pushing ... and as it built up pressure, it started bending the pipe upwards, which caused the failure."

There were relief check valves all along the length of the flume to relieve pressure, "but if one of those failed, it would cause the pipe to collapse. But in this case, there was just too much water coming and nowhere for it to go except to buckle the flume," Northcutt said.

Northcutt added that whenever the Duck River rises, it reaches the same level inside the flume when the waters back up into it from the river. But so does all the storm water draining from a large part of Shelbyville, and it ends up in a detention basin near the corner of North Cannon Boulevard and West Jackson Street.

Water from Big Spring, which is located in the area under the flume, is also sent to the basin in a separate pipe. Water from the basin is then pumped into the river.

Northcutt also stated that in 1963, there was no local flood control from upstream on the Duck, since Normandy Dam had not been built yet.

Repairs

Northcutt said he spent "days inside this pipe before we did anything to replace it," surveying the different sections of the failure to see where it began and how it happened.

"Everything I found at that time indicated that it failed from the bottom and crushed upward, causing the whole thing to collapse," he said.

The repair work lasted from July until December of that year, costing $240,000 in 1963 dollars, but instead of filing a enormous lawsuit, an agreement was reached between the city of Shelbyville, the Housing Authority and Oman Construction to split the costs evenly between them.

Engineers increased the gauge of the pipe "one figure", making the flume thicker, Northcutt explained. "It's held up for [46] years, and I believe that the engineers guaranteed it for 50 years."

The photos dug out of the T-G archives brought back memories for the retired engineer -- including the assassination of President John F. Kennedy.

Northcutt said he was standing on the top of one of the ditches dug for the flume at the corner of North Main and Cannon when the news came in.

After he completed work on the flume, Northcutt decided to settle down in Shelbyville and raise a family.

But 46 years later, he's once again helping with the project that brought him here in the first place.

Hard work ahead

Northcutt said there are no state or federal requirements for inspection of the flume. Public works director Mark Clanton said he has been inspecting the massive pipe about once or twice a year, but there have been no records kept of these inspections.

However, Clanton said he will now start to document his checks of the flume.

While the city is responsible for inspecting it, the flume is actually owned by the Shelbyville Housing Authority.

But Northcutt says there are other problems that will run up the cost of the flume repair.

On the southern side of the flume is a storm sewer pipe which runs to the detention basin -- draining storm water from other parts of Shelbyville.

"It's going to be very hard to go in there and do this (flume) without having to tear that up also," he said. "It will probably have to be replaced."

Also, on the north side of the damaged area, an 18-inch sanitary sewer line lies about a foot and a half below the inverted flume.

There is a water line that runs through the area as well.

Northcutt said that Clanton "has an enormous job in front of him."

"The construction of this is going to be very expensive, and it's going to take awhile."

Current estimates put the scope of work at six to eight weeks, Northcutt said, "and they'll be doing real well to get it done by then."