In one of its briefer regular meetings Monday, the El Dorado Irrigation District Board of Directors unanimously approved three projects totaling a tad under $453,000.
With two members absent the board voted 3-0 to approve the three capital projects, with Directors Bill George, John Fraser and Alan Day present.
The least expensive item was a $57,000 contract with Webster Environmental Associates to track down odors at the El Dorado Hills Wastewater Treatment Plant.
The EDH sewer plant averages six odor complaints a year, said Wastewater Operations Manager Vickie Caulfield, but so far this year there have been eight complaints. That is partly a reflection of the construction of new homes next to the EDH sewage treatment plant. Adding in staff time on a capital project, the final approved funding came to almost $59,500.
The plant’s permit from the state requires odors to be confined to the property. Two kinds of odors are hydrogen sulfide, which produces a rotten egg smell, and ammonia, methane aerosols and volatile organic compounds.
Caulfield said the odors are most noticeable in the morning or late at night when the ambient temperature is cooler than the sewage being treated.
“Because of the cost of a sewer plant upgrade, we thought we ought to take a step back,” Caulfield said.
She added the initial estimate of doing the odor study ranged from $40,000 to $250,000. The bid from Webster Environmental was selected because of its specialized expertise in odor control analysis, Caulfield said.
In May the board had authorized spending $83,000 to replace the granular activated carbon in two equalization odor scrubbers at the EDH plant.
Webster Environmental will begin the study July 29.
“It has to be done in the summer, because that’s when we have the most odors,” Caulfield said.
The next least expensive item was a $66,900 change order for a project underwritten by the California Energy Commission and being executed by Domenichelli & Associates.
The original contract, executed in July 2009, was for $275,000 to analyze energy production in district water delivery systems and “improve pumping efficiencies.” The change order is reimbursable up to $52,000 to the district by the El Dorado County Water Agency.
The highest cost item approved Monday was $239,000 to buy a Duperon automatic bar screen and washing press for the El Dorado Lift Station that sends sewage through the El Dorado Force Main to the Deer Creek Wastewater Treatment Plant.
The lift station was built in 1975 in the townsite of El Dorado and serves 2,534 homes. The sewer lift station has been rehabilitated in phases over the years, but the current screen for fecal solids is prone to jamming and other parts of the mechanism are becoming difficult to repair, according to EID engineer Tim Sullivan.
The new system will be similar to one the district purchased in 2010 to use at the Deer Creek sewer plant. The new screen will have 3/8 inch gaps and the whole system will be enclosed to minimize flies.
Estimated expense for district crews to install the new Duperon automatic bar screen and washing press is $57,600 and contingencies are estimated to be $29,700 for total capital expenditures of $326,600, funded by sewer rates.