Item:
Title
Capital Project Amendment No. 18CPA000010 for the new Rougemont Community Water System (RCWS) pH Control System Capital Project and Budget Ordinance Amendment No. 18BCC000039 Transferring $107,175 from the Capital Financing Plan Fund to the PAYGO Fund to Fund the RCWS pH Control System Project
Body
Date of BOCC Meeting: June 11, 2018
Request for Board Action:
Agenda Text
The Board is requested to approve Capital Project Ordinance No. 18CPA000010 for the new Rougemont Community Water System (RCWS) pH Control System Project and Budget Ordinance Amendment No. 18CPA000039 transferring $107,175 from the Capital Financing Plan Fund to the PAYGO Fund to fund the RCWS pH Control System Project.
The RCWS became operational in September of 2016. The existing treatment system consists of sodium hypochlorite for disinfection and zinc orthophosphate for corrosion inhibition. Durham County completed an Optimum Corrosion Control Treatment (OCCT) study in June of 2017 at the request of the North Carolina Department of Environmental Quality (NCDEQ). NCDEQ requested the OCCT study based upon previous sampling events that indicated copper samples from individual homes were above the regulatory Action Level of 1.3 mg/l and a system pH of less than 6.8 s.u.
In response to the OCCT study, NCDEQ issued a letter dated October 24, 2017 approving of the following treatment methods to minimize the copper corrosion within the distribution system:
1. Increase the pH of the water to a range between 7.2 and 7.8 s.u. using soda ash within the distribution system; and
2. Continue orthophosphate based corrosion inhibitor to maintain a residual of 1.0 mg/l in the distribution system.
Increasing the pH from 6.8 s.u. to between 7.2 and 7.8 s.u. will result in increased efficiency of the zinc orthophosphate for corrosion inhibition.
The letter issued by NCDEQ stated the pH adjustment system must be operational by October 2019. County staff prepared and issued RFQ 18-011 in ...
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