City of Bartlesville utility customers who live or work south of Turkey Creek and east of the Caney River experienced very low water pressure for several hours last Friday after a water line break on U.S. Highway 75 south of Adams Boulevard. Water Utilities Director Terry Lauritsen gives us the details in this week’s Director’s Cut.
First, what happened, exactly?
Around 3 a.m. on Friday morning, one of the discharge lines from the Toalson pump station, which is the pump station at the Hot, Warm and Cold tanks, ruptured on the west side of U.S. Highway 75 across from Walmart.
The Toalson pump station supplies water to the southeast area of town and has two discharge lines, a 24-inch and a 12-inch diameter pipe. To determine which line the leak was on, the pump station had to be shut down.
The leak was large enough that the system lost significant pressure from 4 a.m. to 7 a.m., and the pressure in this portion of the system was reduced to around 20 pounds — we normally run in the 60 to 70 pound range. By 8:00 am, we were able to determine that the break was on the 12-inch line. Around 9:30 a.m., we isolated this section of line and began pumping around the break through the 24-inch line. By 10 a.m., we had restored partial pressure — 45-50 pounds — to this area of the system. To help ease the system back and avoid surges that could have caused other pipes in this area of town to rupture, we kept the pressure low until the pipe was repaired. The pipe was repaired by 2:45 p.m. and full pressure was restored to this area by 3:30 p.m.
What causes this?
We suspect that the rupture was due to the extended dry conditions causing soil movement at the depth of this water line. We have been experiencing a higher than normal rate of water line breaks during the last couple of weeks due to these dry conditions.
Why was water service interrupted for so many people?
This pump station serves customers south of Turkey Creek and east of the Caney River. The City has 2 million gallons of elevated water storage to serve this portion of the system. At the time of the break, we had approximately 1 million gallons of water in these storage tanks. The break occurred just before we started experiencing higher usage from irrigation systems and customers getting ready for the day. The size of the break, combined with this higher usage, quickly consumed this storage and caused the pressure in this portion of the system to be reduced. Areas west of the Caney River and north of Turkey Creek were not impacted by this leak.
How long were residences, business and schools, etc., without water, and why did it take so long?
No one was completely out of water, but the pressure in the system was reduced enough that some customers experienced water just dribbling out of their faucet. Most residential water fixtures require a minimum of 25 pounds of pressure to operate correctly and schools/larger commercial entities require a minimum of 40 pounds of pressure for plumbing fixtures to operate correctly.
The leak required seven valves to be closed to isolate these lines to determine which one was broken. There was one valve that did not close very tight, and the back pressure in the system continued to feed these pipes, which caused delays in determining which line was broken and slowed progress to make the repair. City crews were fighting a substantial amount of water coming into this section of pipe. The valve that was not working correctly will be replaced.
How can this be prevented from happening again, or can it?
Unfortunately, this cannot be prevented. The City tracks the age of the water lines within the system and programs replacement projects for lines that meet certain age, material and/or soil conditions. Typically, water lines of this material — ductile iron — have an average service life between 80 to 100 years. This 12-inch line is approximately 65 years old and this was the first leak experienced on this line.
How many pump stations does Bartlesville have?
The City has four external pump stations outside of the water plant that supply water to different pressure zones within the water system. Due to the topography of Bartlesville, the water system is broken into different pressure zones that are isolated from each other. Outside of the pressure zone supplied by the water plant, Toalson is the next largest pressure zone.
Overall, the average age of our water distribution system is 60 years. Since 2015, the City has replaced 8.25 miles of water lines. Within the last couple of years, the City has been ramping up the water line replacement program and we currently target replacing approximately 2 miles of water line per year. These projects are funded by water customers through the capital investment fee that is a separate charge on the utility bill.