Arsenic

Arsenic is an element that occurs naturally in rocks, water, plants, and animals. It is also used by industries as a wood preservative and in the manufacturing process of paints, drugs, dyes, soaps, metals, and semi-conductors. The current federal and state maximum contaminant level (MCL) for arsenic is 50 parts per billion (ppb). Effective January 2006, the EPA will lower the MCL from 50 ppb to 10 ppb. In 2003, the Utilities Department determined that 7 of the City’s 25 groundwater wells have arsenic concentrations above the future MCL of 10 ppb. Therefore, these wells will require some action to meet the new MCL by January 2006.

Arsenic Mitigation

The Utilities Department is currently evaluating arsenic mitigation methods to ensure the wells comply with future EPA arsenic regulations. Arsenic mitigation techniques include both treatment and non-treatment methods, and the City anticipates that both types of methods will be used to bring the 7 wells into compliance. Some of the wells are very near the new 10 ppb MCL, so a nontreatment method—blending with low arsenic water—is being evaluated for these wells. In this technique, water above the new MCL from a groundwater well is mixed with water considerably below the new MCL. The blend results in water below the 10 ppb arsenic MCL. Another non-treatment method, called well rehabilitation, is also being considered for wells near the new 10 ppb MCL. Well rehabilitation involves analyzing the arsenic concentration at several zones within a well. If high arsenic levels are identified, those zones can be sealed off, thus preventing high arsenic water from flowing into the well. If blending or well rehabilitation is not viable for a particular well, the Utilities Department will proceed with on-site treatment, which would involve building a treatment system at the affected well. On-site treatment is the last option to keep all wells operational in 2006 because of the continued operation and maintenance expenses.

Lead and Copper

Samples were collected from 70 homes, primarily from homes built between 1980 and 1984

Percentile reporting means the data is first organized from smallest to the largest. In the case of copper, there were 70 samples ranging from 0.01 to 0.45 mg/L. We then determine which sample to evaluate by taking 90% of 70 which is 63. We then pick the 63rd data result from the smallest as the reporting level. In this case, 0.27 mg/L. Ninety percent of the data is below 0.27 mg/L while the remaining ten percent is above. For lead there were also 70 samples and the 90th percentile was ND or no detection.

Possible Sources: 1-Erosion of natural deposits, 2-Home plumbing systems.

Radiological 

Tested but not found in Pyramid Peak: Radon

Radon is a radioactive gas that you cannot see, taste, or smell. It is found throughout the United States. Radon can move up through the ground and into a home through cracks and holes in the foundation. Radon can build up to high levels in all types of homes. Radon can also get into indoor air when released from tap water from showering, washing dishes, and other household activities. Compared to radon entering the home through soil, radon entering the home through tap water will in most cases be a small source of radon in indoor air. Radon is a known human carcinogen. Breathing air containing radon can lead to lung cancer. Drinking water containing radon may also cause increased risk of stomach cancer. If you are concerned about radon in your home, test the air in your home. Testing is inexpensive and easy. Fix your home if the level of radon in your air is 4 picocuries per liter of air (pCi/l) or higher. There are simple ways to fix a radon problem that aren’t too costly. For additional information, call your State radon program or call EPA’s Radon Hotline (800-SOS-RADON).

Possible Sources: 1-Erosion of natural deposits