The Department of Public Health recently investigated the new site for the Woodland-Davis Clean Water Agency surface water project treatment facility and its close proximity to the city of Woodland’s existing wastewater treatment plant, but has so far discovered no apparent danger to the future drinking water supply.
However, while the water agency has met the majority of the state’s demands to ensure the safety of that supply, it still must pass an aerosol test to determine whether wastewater pathogens pose a threat.
The two plants sit just across the street from one another on Co. Rd. 24 in Woodland — the water treatment plant site is set back a few hundred yards on the edge of a few dried up ponds to the north of the road — however, the areas of concern are about 2,000 feet apart, according to the water agency.
The Woodland-Davis surface water project, pending the Measure I election, will pump water from the Sacramento River to the treatment facility under investigation and then pipe the water off to the two cities, replacing their ground well drinking water supplies.
“The relocation of the proposed site, to be as far as possible from the city of Woodland’s wastewater treatment plant, has addressed many of CDPH’s concerns,” said Richard Hinrichs, chief of the department of public health’s division of drinking water and environmental management in Northern California, in an email to The Enterprise.
“If the study concludes that aerosols remain a concern,” Hinrichs added, “the agency will consider various mitigation measures including … modifying the aeration system at the wastewater plant, physical barriers at the wastewater treatment plant and/or at the water treatment plant such as trees or walls and, as determined to be necessary, physically covering certain water treatment plant basins that would otherwise be open to the atmosphere.”
Dennis Diemer, general manager of the water agency explained in more detail what the health department is concerned about earlier this week.
“Giant brushes that aerate the wastewater (could cause) mists of wastewater that would leave the plant and travel over to the water plant and somehow enter into … the treatment water and into the filters,” he said.
Diemer said that covering the water plant basins — the worst case scenario — could cost somewhere in the ballpark of $300,000 to $400,000.
The water agency will conduct the aerosol study in collaboration with UC Davis to determine what steps need to be taken. Diemer expects to have results of the study by the fall. Construction of the project is estimated to begin in late 2013.
In April, when the water agency decided to move the site of the water treatment facility because it wanted better vehicle access around the plant, it contacted the state to receive its regulatory blessing that it could be safely built at the new location.
The department of health established several requirements for the Woodland-Davis surface water project to meet before it would consider permitting the treatment facility, including for:
* Aerosols or dust from the wastewater treatment plant transporting pathogens into open impoundments, basins, or ponds at the water treatment plant.
* Natural disaster (e.g., flood, earthquake) that may result in wastewater contamination of the water treatment plant site that would not occur, or would be less likely to occur, if the water treatment plant site were at the originally designated site.
* Shallow, contaminated groundwater in the area entering an impoundment, basin, or pond at the water treatment plant while dewatered for maintenance or repairs.
* Contamination of the water treatment plant through the sharing or borrowing of tools or equipment between the water treatment plant and the wastewater treatment plant.
According to Hinrichs, the water agency has met the majority of those standards. The state also has no set regulations for required distances between potable and wastewater treatment facilities.
Michael Harrington, spokesman for the No on Measure I Committee, however, believes this situation demonstrates only one of the many flaws with the surface water project.
“Members of the No on I committee have thought for several years that the city was rushing the surface water project with inadequate technical, physical and rate studies,” Harrington said. “Now we learn that the plant is potentially sited too close to the wastewater treatment plant such that harmful bacteria and waste byproducts might be carried in dust into the new clean water plant.
“It’s disturbing that this far along in the process, people opening their ballots right now are doing this with inadequate information: whether or not these two facilities are sited too closely to meet state health standards. We know that they need to do the study, but the question is why is it so late such that the public doesn’t have the information about this subject?”
Chair of the Yes on Measure I Committee, Alan Pryor, after talking with the project’s engineers, West Yost Associates, claims there are no problems, even with aerosols.
“Typically, aerosols from a wastewater aeration pond will drop out of the air within several hundred meters,” Pryor said in a text message. “The distance from the aeration ponds and the WDCWA water treatment plant is about 2,000 ft. Thus there is not likely to be any problem.”
“Even if you had a gale-force wind … that could potentially carry an aerosol that far, because all the water is in sealed vessels and pipes after complete disinfection by ozonation, there is absolutely not chance of contamination of the purified water.”
— Reach Tom Sakash at [email protected] or 530-747-8057. Follow him on Twitter at @TomSakash