After refusing toward the end of last year, the Willcox City Council recently voted to install a natural gas backup power system for the City's Well No. 3, located about five miles north of town.
The Council voted to contract with Willcox-based Bill's Pump Service at a cost of nearly $25,000 to retrofit Well No. 3 to operate on natural gas as an alternate power source.
John Bowen, the City's utilities supervisor, said he expects that the new pump would be installed by the end of April.
In his Jan. 7 letter, Bowen reminded the Council that this agenda item failed to pass at both the Nov. 2 and Dec. 3, 2012 meetings.
Councilwoman Monika Cronberg, who had voted with “the prevailing majority on the motion,” nonetheless asked that the item be brought back to Council for further consideration, he said.
Councilman Sam Lindsey explained later why he was against the proposal originally.
“I was under the impression that No. 3 was used as a back-up well only,” he told the Range News.
“I later found out that is the most used well because it is the cheapest well to operate.”
“My thought was that it could have a regular angle drive with an engine converted to natural gas,” said Lindsey, adding, “When I found out it was used all time that changed my thinking which made me think the dual drive would be best.”
Bowen explained, “During a past emergency preparedness assessment, staff concluded that the delivery of potable water to citizens was our prime area of concern.”
The City's Water Section has three domestic water wells about five miles north of town, he said.
Two wells pump in excess of 1,000 gallons per minute each, with the third pumping about 300 gallons per minute, said Bowen, adding that the third well (No. 3) produces about 432,000 gallons per day.
“Our 1.5 million gallon storage tank is on automatic set points controlling the level between a high of 1.4 million gallons and a low of 900,000 gallons,” he said.
“In 2011, daily water usage during the four coldest months of November, December, January, and February – when no one is irrigating landscaping or running evaporative coolers” – was about 394,000 gallons per day, Bowen said.
“Staff reasoned that the four cold months more accurately showed the necessary household water consumption,” he said explaining that, based on that assumption, “we investigated various methods to insure water delivery from Well No. 3, in case of an extended electrical power outage.”
Electric backup generators were the first option considered.
“It was calculated that a 130KW natural gas generator would be required to start the pump under full load,” Bowen said.
“Natural gas is available at the well site, and is a less expensive fuel than either gasoline or diesel, both possibly being in short supply to a natural disaster.”
With $28,000 budgeted, “the natural gas generator proved to be more cost than budgeted at more than $35,000 with cost, taxes, firefight, and required electric transfer switch,” he said.
“The larger V-10 6.8 L engine in the generator would be fuel inefficient compared to other options.”
Then-Councilman Stephen Klump suggested a right-angle pump drive as used by local farmers, Bowen said.
Investigation found that the Cities of Douglas and Tombstone are currently or have used a combination electric/natural gas right angle pump drive to pump water in the event of a power outage, he said.
“The much smaller V6 direct drive application will run more efficiently and at a more than $10,000 initial savings.”
In the event of an electrical outage, City staff would go to Well No. 3, “switch off the electrical disconnect, start the natural gas engine, and allow it to warm up sufficiently before engaging the clutch to the right angle drive,” said Bowen, adding, “Once electric power is restored, the process is reversed and the electric pump motor is started.”
Bowen told the Council that the engine would only be operated in an outage situation, except for maintenance operation 20 to 30 minutes a month.
Southwest Gas has estimated a $43 monthly fee plus gas consumption, he said.
City staff requested quotes from five pump companies and received three responses: Bill's Pump Service, $24,837; Gilbert Pump and Equipment, $26,608.31; and Bestway Electric Motor Service, $28, 167.30.
The amount of $24,837.38 will come from the Water Capital Improvement funds, which had $28,000 budgeted, Bowen said.
“With the new back-up, it is very easy to go from one fuel to the other,” Lindsey told the Range News.
“We can operate several days with the output from storage tanks and production from No. 3 and not have to restrict usage.”
Vice Mayor Bill Holloway told the Range News, “It is important that City leadership (staff and council) always work to maintain services, and providing services includes backup systems. I am glad the City Council agreed on the natural gas backup system.”