Baker City operates an unfiltered surface water supply. The Long Term 2 Enhanced Surface Water Treatment Rule (LT2 or LT2ESWTR) issued by US Environmental Protection Agency (EPA) requires unfiltered surface water systems to achieve removal or disinfection of Cryptosporidium, an organism that can cause gastrointestinal distress or more severe health impacts for those with compromised immune systems. The existing chlorine disinfection system is not sufficient to provide the required disinfection. This regulation is requiring additional treatment by Baker City, similar to other cities including Walla Walla, Portland, Tacoma, Bremerton, and Seattle.
A study reviewed the available treatment alternatives: membrane filtration to remove Cryptosporidium or disinfection to inactivate Cryptosporidium with ultraviolet light, ozone, or chlorine dioxide. The evaluation of alternatives indicates that disinfection with ultraviolet (UV) light is an attractive option to comply with the requirements of LT2. UV is the least expensive option, simple to operate, reliable, and fits well into the gravity flow hydraulics of the existing water system.
However, for UV disinfection to be sufficient treatment into the future, the City must maintain its exemption from filtration. This depends on natural water quality, watershed protection, and approvals by Oregon Department of Human Services. Also, UV disinfection provides no protection against degraded water quality resulting from forest fires. Protection against forest fires and maximum reduction in regulatory risk could be achieved by membrane filtration, but at significant additional expense.
A new UV disinfection is anticipated to cost in the range of $1.5M to $2.5M to construct and may add $13,000 per year in operating costs for the City. The State has granted Baker City a two-year extension and compliance is now required by October 1, 2016. To meet this schedule, it is recommended that the City move forward with equipment selection and regulatory coordination in 2010-11, design in 2011-12, and construction in 2012-13. This schedule is intended to allow sufficient operational experience prior to the 2016 compliance deadline.
Source: the article above was adapted from the Technical Memorandum - Disinfection Options to Comply with LT2ESWTR prepared by HDR Engineering, INC on November 22, 2009.
Below you will find current information about this project:
- Technical Memorandum - Disinfection Options to Comply with LT2ESWTR
- City Council Meeting December 8, 2009 - Item #6 Water System Improvements Recommendation: Staff Report and Minutes
- City Council Meeting May 25, 2010 - Item #9 Approval of Task Order #2 with HDR, Inc. for Water System Improvements: Staff Report and Minutes
- City Council Meeting October 25, 2011 - Item #7 UV Filtration Task Order #3: Staff Report and Minutes
- City Council Meeting November 1, 2011 - Item #4 Discussion Regarding Water Treatment: Minutes
- Presentation: Long Term 2 Enhanced Surface Water Treatment Rule - Compliance for Baker City, Oregon
- Centers for Disease Control and Prevention - Cryptosporidium
- Presentation: Kick-off Meeting & Technology Workshop - January 12, 2012
- City Council Work Session February 28, 2012: Agenda Packet + Additional Materials Video