What is the ‘arsenic’ fuss all about?
In October 2001, the U.S. Environmental Protection Agency (EPA) announced its decision to lower the arsenic standard for public water systems from 0.05 mg/L to 0.010 mg/L (50 parts per billion (ppb) to 10 ppb, respectively). The effective date of the revised rule and new standard is January 23, 2006.
In Nogales, there are three public drinking water wells that must be treated and we will use what is called Source Rehabilitation. In other words, we will be treating each of the three (3) wells not in compliance with the new standard.
Why do you care?
The purpose of the new standard is to protect public health by reducing the occurrence of carcinogenic (e.g., lung and bladder cancers) and non-carcinogenic (e.g. skin damage, circulatory disorders, etc.) diseases that can result from unhealthful levels of arsenic exposure.
How does arsenic get into the water supply?
Arsenic occurs naturally in groundwater and is found in rocks, particularly in rocks from through volcanism, vegetables and the human body. It can enter drinking water supplies in communities where groundwater makes up a large part of the total water supply, like Tucson. Arsenic dissolves into the groundwater and is then drawn into the wells that provide your drinking water.
We aren’t alone with this problem compared to the rest of the United States, the occurrence of arsenic in ground water tends to be higher in western states and states in the Great Lakes region.
Why do we have to treat the drinking water systems?
The new arsenic standard is federal law.
How will Arizona implement the new law and when?
Arizona's Department of Environmental Quality has a Master Plan. Read More
How will Nogales treat the water? 
Nogales has chosen an Iron adsorption system manufactured by Severn Trent. The removal technology is iron adsorption–a process in which raw water (untreated water directly from the well) enters a chamber in which iron media is present. Arsenic has a natural affinity for iron, and so it will “stick” to the iron media, thus reducing the level of arsenic in the water.
How did we choose this system and what is the schedule?
Following is a current status of the project:
I. No contract has been issued or agreed to except for the purchase of equipment. There is NO contract to construct at this point. Any procurement action will be according to standard construction procurement practices and need Council approval.
II. Options Analysis was Commissioned through an engineering firm to evaluate:
- Existing technologies and systems
- Treatment Requirements locally
- Treatment Alternatives
- Site Layout Options
- Cost Analysis (Using information obtained directly from manufacturers)
III. Iron adsorption system selection was made by by City staff based on pre-established criteria including (but not limited to) initial costs, cost to maintain, training requirements, and disposal costs.
IV. Project identified and approved as part of bond issue
V. Cost/Schedule & Expenditures to date:
- Approximately $915,000 for equipment purchase was approved by City Council in August, 2005.
- Check for 10% (About $91,500) to order and secure equipment.
VI. Milestone Schedule for Design and Construction
- February 2006-Preliminary review of Westland Resources design, bid specs and docs required the open competition of the contract to construct.
- March-April 2006 – Equipment delivered, final design complete, ADEQ review and approval to construct.
- May 2006 – Request for Proposals
- June-July 2006 –Contract awarded for installation and related construction.
Questions? Contact Us
