Quality of treated water

Print

No FOG in the septic system

Fats, oil, and grease are collectively referred to as FOG. The Sedona Wastewater Department requests that you not place fats, oils, and grease down your sewer drain. FOG clogs sewer pipes. Although it may be liquid when  poured down your drain, as these materials travel miles down the sewer line they cool and solidify. As FOG solidifies it builds up on the walls of the sewer pipe. This reduces the space in the pipe available for sewerage flow. If  space in the pipe is reduced enough the sewerage will flow out of the  manholes, other surface openings onto the ground.

You can reduce the amount of FOG in the sewer system. 

  • Consider saving the fat, oils, and greases for reuse. Reusing frying grease is common and safe when done properly. Reuse your grease for as long as you like until it becomes rancid. Smell the grease before each use. When the odor becomes acrid and pungent, you should dispose of the grease.
  • Pour liquid grease and oil into containers such a cans, bottles, and milk cartons.  Dispose of these in your garbage can.
  • Scrape plates, pots and pans over the garbage.
  • Reduce garbage disposal use. Many foods, such as vegetables contain significant amounts of FOG, which is released when the food goes into the disposal.    


The Quality of Treated Water

The city has undertaken several tests to gain a better understanding of the quality of its treated water at the Wastewater Reclamation Plant.  This includes testing for the presence of Constituents of Emerging Concern (CEC) in the treated water and comparing the water's quality to State and Federal drinking water standards.  The city has performed this investigation as part of its evaluation of a program to develop injection wells which will put treated water into the aquifer below the city’s Wastewater Plant.

CECs  are  chemical compounds, many of which are  found in items such as pharmaceuticals, personal care products ( for example deodorants, make-up, lotions, shampoo),  food additives ( for example caffeine, sweeteners, preservatives), and other consumer products.  Chemicals from these products enter the waste water system as we dispose of water used in  pools, restrooms, showers, and other places.  The waters draining to the wastewater plant contain high levels of chemicals from these products.   Even after treatment, although over 90 % of the chemicals may be removed, some remain and can be detected in parts  per trillion using modern testing methods.[1] The concern arises because the presence of most of these chemicals in drinking water is generally unregulated and their potential for health impacts in drinking water has not been fully assessed. The City has tested for the presence of  over 100 of these constituents. [2]

A report completed in August 2014 states none of the CECs tested for were found in the water samples from Arizona Water Company and Oak Creek Water Company.  In Oak Creek (the stream not the water company)  only DEET, an ingredient in insect repellent, was found using current detection methods.   The treated Wastewater Plant water contained higher levels of CECs. This is not totally unexpected considering the focused disposal of these compounds in the relatively limited quantity of water in the wastewater system as compared to an aquifer[3].   On average the City’s current treatment process reduces the levels of the analyzed CECs in the water by about 90%[4].   These levels are well below the levels developed by the WaterReuse Research Foundation in their recommendations for direct potable reuse.[5]

The quality of water at the plant has been compared to State and Federal drinking water standards.   To date the it has  been determined that the treated water meets drinking water standards, although the City is not using it for drinking water.  Current State regulations do not allow it to be directly used as drinking water.  

Below are links to the various reports the City has conducted and the text of a statement by Dr. Shane Snyder to the Senate Subcommittee on Transportation Safety, Infrastructure Security, and Water Quality in April 2008.

 

Testimony of Dr. Shane Snyder to the Senate Subcommittee on Transportation Safety, Infrastructure Security, and Water Quality in April 2008 Snyder

February 2014 Report   Full report  |  Short version

August 2014 Report   Full report  |   Short version

[1] One part per trillion is 1 drop of water in 20 Olympic-size swimming pools (13,200,000 gallons
[2] There are hundreds of compounds but the ones tested are common in municipal wastewater
[3] Drinking water for the City of Sedona is drawn from aquifers below the city.
[4] If the impact of the sweetener Sucralose is removed from the result the process removes 99%.
[5] Direct potable reuse means no further treatment of the treated wastewater before using it as drinking water. Water injected into the aquifer at the Sedona plant would receive additional treatment through dilution and subsurface movement of the water.