Saturday, Sept. 12, 2009 | 1:59 a.m.
Boulder City is beginning a long process to recycle its wastewater.
A study was recently completed laying out the alternatives to the city’s current system, which is sending effluent from the city’s wastewater treatment plant out two channels into the desert of the Eldorado Valley, where it evaporates and seeps into the ground before it reaches U.S. 95.
Boulder City is the only municipality in the Las Vegas area that disposes of its wastewater rather than selling it or returning it to Lake Mead, which gives the Southern Nevada Water Authority credit toward its annual allotment of Colorado River water, Water Authority spokesman J.C. Davis said.
Boulder City does not have the option of returning its wastewater to Lake Mead, because it would cost too much to build a pipeline over the mountains surrounding the city to deliver it to Lake Mead, City Manager Vicki Mayes has said. Water from the Las Vegas Valley flows through natural washes back into the lake.
In comparison, Mesquite recycles all of its wastewater to water the seven golf courses in the city and its parks, Mesquite Economic Development Director Bryan Dangerfield said.
Boulder City does sell a fraction of its daily effluent flow to a quarry for gravel washing and dust control.
The Boulder City Council has directed city staff to begin the planning that will be required to eventually sell more of its wastewater for industrial use to a second gravel producer and a future solar power generator or other plant in the Eldorado Valley.
Boulder City’s wastewater disposal system was questioned in 2007 after one of the channel banks broke and some of the treated effluent flowed into the Boulder City Conservation Easement, a preserve for tortoises and other desert wildlife owned by Boulder City but managed by Clark County. To address concerns by the county and the Nevada Division of Environmental Protection, the city agreed to study alternatives.
Jacobs Engineering Group presented those alternatives to the City Council on Tuesday, and the council voted unanimously to make selling its effluent for industrial use a long-term goal.
The plan will require about $8.7 million to build pipelines from the wastewater treatment plant to the industrial sites in the Eldorado Valley and to increase the quality of the wastewater so it is suitable for industrial use, Jacobs engineer John Connell said. With the revenue from selling the water, the city could recoup that cost in 14 to 23 years, Connell said.
Even with the new system, not all of the wastewater would be sold, given the current industrial demand, the Jacobs report says. Industrial reuse would take about 40 percent of the current effluent supply, the report says.
Treating the water to the higher level required for irrigation use and delivering it to the city’s two municipal golf courses would cost $12.8 million and would not supply enough water to irrigate the courses nine months of the year, Connell said.
The other choices were to modify the existing channels at a cost of $100,000 or to create new rapid infiltration basins, a sort of evaporation or holding pond, for $6.8 million.
Public Works Director Scott Hansen said it didn’t make sense to modify the existing channels. The state encouraged the city to remove vegetation in the channels, he said, but the vegetation is holding the sand in place.
“When constructing a new channel without firm banks, you’re gambling a little bit,” he said. “Will the water stay in the channel or not? Do you need to vegetate the banks?”
Public Works crews are monitoring the channels daily to catch any leakage early, Hansen said. That should avoid a repeat of the 2007 incident, he said.
“The problem was that it ran for days,” Hansen said.
In addition, he said, the state recently renewed the city wastewater permits for five years, buying some time.
“As long as we are moving in the right direction to get the water away from the conservation area, they will give us leniency,” he said.