View Mobile Site
 

Ask the Expert

Signal Photos

 

Chloride removal options outlined

Water: Sanitation District preparing reports examining financial, environmental costs

Posted: February 13, 2012 2:00 a.m.
Updated: February 13, 2012 2:00 a.m.
 


The Santa Clarita Valley Sanitation District is gearing up to prepare two reports that will examine the costs — both financial and environmental — of removing chloride from the Santa Clarita Valley’s wastewater.

Preparation to begin the reports is the first step in a yearlong process to come up with solutions to high chloride levels in the Santa Clarita Valley’s wastewater. Although the levels of chloride have dropped — thanks in part to the removal of more than 7,300 salt-discharging water softeners in the Santa Clarita Valley — the detected amounts of the naturally occurring salt are still over the limit of 100 milligrams per liter of water, according to Sanitation District officials.

During a public meeting Thursday night attended by about 15 residents, sanitation officials explained that if the district does not come up with a solution to the chloride limits, they will be forced to pay steep fines enforced by the Los Angeles Regional Water Quality Control Board.

The fines would be passed on to sewer-system ratepayers in the Santa Clarita Valley.

Average amounts of about 65 milligrams of chloride per liter of water are found in both imported water and in water from local groundwater wells, said Mary Jacobs, senior engineer with the planning department for the Sanitation District.
Santa Clarita Valley tap water is about a 50/50 mix of imported water and groundwater.

To that 65 milligrams per liter, an average amount of about 45 milligrams per liter is added from normal activity in homes and businesses before the water is discharged into the sewer system.

About 10 milligrams per liter is added in the treatment process before the waste water is dumped into the Santa Clara River.

With all of the additional salt from human activity and wastewater treatment, the average amount of chloride in Santa Clarita Valley wastewater is about 120 milligrams per liter, according to Jacobs. That amount can reach as high as 140 milligrams per liter in times of drought.

The Regional Water Quality Control Board has given the Sanitation District until Dec. 31 to prepare and submit plans to decrease the amount of chloride in discharged wastewater.

Many of the residents who spoke about the proposal on Thursday night offered solutions to the problem other than those being considered by the Sanitation District, asked for a delay to the environmental impact report process, or were upset that Santa Clarita Valley residents were going to have to foot the chloride-removing bill when the water residents use arrives with chloride already in it.
Sanitation District officials declined to put a dollar amount to the costs of removing chloride from wastewater.

“This should have been looked at 10 years ago,” Newhall resident Nanette Meister said. “Let’s postpone this decision. I’d like to know what other cities do.”

Suggested treatment methods

A number of methods to treat wastewater have been suggested, including building an advanced wastewater treatment plant and using ultraviolet light to treat microorganisms in wastewater instead of adding chlorine to the water.

Some of the methods would be used at both the Saugus and Valencia treatment plants while others would be used at only one plant.

Each of the following methods will be examined for both the financial costs and the potential environmental effects in a facilities plan and an environmental impact report, both of which should be out in draft form in July, said Chuck Boehmke, assistant department head for the Sanitation District’s facilities planning department.

“Ultimately, the ratepayers will be paying for the upgrades that are needed,” Boehmke said.

* Ultraviolet light disinfection: While the typical chlorine-based disinfection process adds about 10 milligrams of chloride per liter of water, disinfecting the wastewater with ultraviolet light would minimize the amount of added chloride. This process would be used at both the Valencia and Saugus plants. Jacobs said this option by itself would be insufficient to reduce the chloride levels to the acceptable limit.

* Reuse of recycled water: The Castaic Lake Water Agency is projecting an increasing need for recycled water in the Santa Clarita Valley. If enough recycled wastewater is used to irrigate landscaping and used for other purposes, there’s a chance that the need for drinking water would drop and the discharge of treated wastewater to the Santa Clara River would also drop, which could impact wildlife in the river.

* Advanced wastewater treatment facility: Although the wastewater from both the Valencia and Saugus plants is filtered through a three-step process, none of the filtration methods are effective at reducing chloride. The Sanitation District is proposing a salt-removing system that includes microfiltration for pretreatment, which would then be followed by reverse osmosis — a process that produces ultra-clean water by forcing it through a membrane with microscopic openings. The reverse osmosis plant would be sized only large enough to meet the chloride limit.

This facility would be located at the Valencia treatment plant. If reverse osmosis is used, additional methods would have to be used in
addition to the advanced wastewater treatment plant to pump treated water to Saugus and dispose of brine — the salt byproduct after the reverse osmosis process.

* Reverse osmosis product water pipeline: A portion of the reverse osmosis-treated water would be piped from the Valencia plant to the Saugus plant through a new 3.5 mile pipeline. This water would be blended with water treated through the normal three-step process before being discharged into the Santa Clara River.

* Deep well injection for brine disposal: One of the options of disposing of the brine byproduct is injecting it about one mile deep into geologic formations that already contain highly salty water.

* Brine pipeline to existing ocean discharge: A second option of disposing of the brine is by building a 37-mile pipeline to a sewer about four miles east of downtown Los Angeles. The brine would then be flushed to the ocean.

Comments

Commenting not available.
Commenting is not available.

 
 

Powered By
Morris Technology
Please wait ...