Title
WATER SUPPLY INTERIM IMPROVEMENTS
COUNCIL INITIATIVE ADDRESSED:
Provide sustainable water quality & environmental infrastructure
CITY ATTORNEY REVIEW: N/A
SUMMARY STATEMENT:
At a joint City Council and Beacon Hill Commissioners workshop on August 20, 2015, staff presented information regarding potential treatment upgrades at the Mint Farm Regional Water Treatment Plant to improve water quality during the implementation period for developing a new source. These treatment upgrades will also help condition our water mains to receive water from a new source and will be beneficial when the MFRWTP is used as a backup supply after a new source is developed, or for continued use of the MFRWTP should a new water supply not be developed. These improvements may also provide benefit if the MFRWTP is used to supply commercial/industrial process water after a new source is developed.
Confluence Engineering was retained by the City in July 2013 to investigate the causes of and make recommendations to improve water quality in the distribution system. Confluence identified the lack of dissolved oxygen (DO) and low oxidation reduction potential (ORP) as the causes of a number of water quality complaints. After testing DO treatment in a distribution system pipe test rig, Confluence determined adding DO to the treated process would notably improve water quality. Confluence also supported recommendations by staff and Kennedy/Jenks to install chlorine injection equipment at the end of the treatment process, to ensure steady chlorine residual to assist in maintaining a high ORP. The post-treatment chlorination modification was designed; however, bidding and construction was placed on hold at the start of the water supply review process.
Additionally, staff continued to evaluate how to resolve chlorine taste and odor complaints, and in consultation with various consulting engineers and the Dept. of Health, determined that naturally occurring organic nitrogen was reacti...
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