SCR technology consists of injecting ammonia into boiler flue gas and passing it through a catalyst bed where NOx and ammonia react to form nitrogen and water vapor.
A report released by the county in March estimates the original 750 Mw InterGen plants would release 13,040 pounds of nitrogen oxides daily, or 2,380 tons per year, and 1,458 tons of carbon monoxide yearly.
Birdsall said because the four units are reportedly to be identical, the additional 250 Mw unit will be equal to one quarter of the total emissions. But those calculations have not been made.
Birdsall said the parties met Wednesday to discuss the issue and will meet again in mid-July.
He said the addition of the SCR technology is a step in the right direction, but there must be reliable record-keeping, monitoring and proper maintenance of the equipment. Further, he said, all record-keeping must be made available in a usable format.
Other concerns include the amount of carbon monoxide because Calexico is a non attainment area for CO, Birdsall said.
"We fear the carbon monoxide could be significant," he said, adding the parties have discussed CO but that NOx has been the main focus. Birdsall said CO can be reduced through the use of catalytic converters.
According to a presentation by InterGen at the meeting, the new technology is expected to reduce the significant impact level from 0.87 to 0.65, where 1.0 equals no significant impact in environmental study terminology.
InterGen further stated the SCRs are already being installed and will be operational by summer 2003 and emissions monitoring data will be made available.
Meanwhile, Epstein said InterGen will further cooperate by helping establish a local sustainable development program to address environmental, social and economic issues.
Under environmental issues, InterGen says the plant's cooling water needs will be met through construction of a $20 million sewage-treatment plant, that modern power generation technology will be brought to bear and that clean, natural gas will be used as fuel.
Under social issues, InterGen will consult the public via interviews and surveys of affected stakeholders, set up education and public health programs.
Under economic, the company says it is investing $750 million in the region that includes jobs during construction and operations, there are contracting opportunities for local businesses and there will be competitively-priced power for regional growth.
As well, Epstein said, InterGen will support and fund the formation of a Imperial Valley sustainable development committee in the county and Mexicali to include government, businesses, academia and others, to design and implement programs that support sustainable development in the border region.
InterGen will initiate and fund a cross-border volatile organic compounds reduction program to target point source VOC generators. VOCs are a precursor to ozone.
The county is a moderate non attainment area for ozone.
Especially vulnerable to ozone pollution are young children, senior citizens and people with existing respiratory and cardiac ailments, the report states. Since 1998, childhood asthma rates in Imperial County have been two to three times the state average, according to an APCD report.
Staff Writer Rudy Yniguez can be reached at 337-3440.