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173-160-321  <<  173-160-331 >>   173-160-341

PDFWAC 173-160-331

How do I make sure my equipment and the water well are free of contaminants?

(1) All tools, drilling equipment and materials shall be free of contaminants prior to beginning well construction. Contaminants include lubricants, fuel, bacteria that will reduce the well efficiency, and any other item(s) that will be harmful to public health and/or the resource or reduce the life of the water well.
(2) Every new or reconditioned water well, after completion of construction or repair, and before being placed in service, shall be cleared of all foreign materials, and free of contamination.
(3) The well casing shall be swabbed and cleaned to remove oil, grease or joint dope.
(4) All pumping equipment, sand or gravel used in gravel-packed water wells and the well casing shall be thoroughly sluiced with clean water and disinfected. The disinfecting agent shall be safe and not impair the potability of the groundwater. All disinfectants shall be used in accordance with manufacturer's recommendations.
(5) Before the well is put to use, the standing water in the well shall be disinfected and flushed to remove all traces of disinfectant. A water sample may then be taken and tested for coliform bacteria or other items required by the state department of health or local health authority. Examples of other test items may include: Nitrates, dissolved solids, sodium, iron, pH, manganese, conductivity, hardness, and turbidity. If testing indicates a presence of coliform bacteria, more stringent disinfecting methods may be required by the department of health or local health authority.
If chlorine is used to disinfect the well water, sufficient chlorine will be added to the standing water to give a residual of fifty ppm free chlorine. The chlorine shall remain in the well for a period of at least twenty-four hours. After twenty-four hours, a minimum of one ppm free chlorine residual shall remain in the water before the well is flushed free of chlorine and a sample taken. Other disinfectants placed in the groundwater shall be used in quantities that are safe, nonpolluting, and that are not a detriment to the potability of the groundwater. All disinfectants used in groundwater shall be used in accordance with manufacturer's recommendations.
(6) Chlorine and other disinfectants can pollute. Allow the chlorine or other disinfectants in the rinse water to dissipate before discharging the water to surface water. This water shall be discharged in a safe manner consistent with the intent of the Water Pollution Control Act, chapter 90.48 RCW.
[Statutory Authority: Chapter 18.104 RCW and RCW 43.21A.080. WSR 98-08-032 (Order 97-08), ยง 173-160-331, filed 3/23/98, effective 4/23/98.]
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