OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details

PWS ID: OR41 00205
PWS Name: COOS BAY NORTH BEND WTR BRD
 
Who Was Contacted: Jeff Page
Contact Phone: 541-267-3128 ext 240 (Email address hidden)
Contact Date: 09/09/2019
Contacted By: PARRY, BETSY (DWP)
Contact Method/Location: Phone
 
Assistance Type: OTHER WATER QUALITY - What if they stopped lime
Reasons: Lead or Copper
 
Details: CBNB uses both caustic soda and lime for proactive corrosion control. The treatment is "proactive" because they have never had an exceedance of either lead or copper. Jeff was asking what they would need to do, compliance-wise, if they decide to use only caustic soda in the future.

In a nutshell, for changes in chemical treatment, EPA requires two 6-month rounds of lead and copper testing at the original number of monitoring sites, not the reduced number. For CBNB, that would mean 60 sites rather than their routine number (30). They would need to wait a couple months after the treatment change before conducting the first round of lead and copper testing. Jeff will research the cost of that extra monitoring versus the cost of maintaining the lime treatment. Although CBNB is in a little different situation because they have never exceeded in lead or copper, this protocol still applies because the chemical change could have an effect on the corrosion potential.

Jeff believes that lime is not adding much value based on observations when they have temporarily taken the lime system offline for pipe cleaning or other regular maintenance. When only the caustic soda is maintaining pH, the pH levels within the distribution system are more consistent. Meanwhile, the lime treatment has poor dosing characteristics and high maintenance. They recently had several weeks of remediation (and cost) to address significant clogging of pumps, etc., in the lime treatment system.

9/26/19 Update - Jeff found the 1992 research identifying the initial 60 priority lead & copper sites, and he will work to identify a few more sites that meet the criteria for good measure. Because the lime treatment has been off a few weeks now, Jeff would like to start the first round of 6-month lead and copper monitoring this fall - in late Oct/ early November. I will set up the 6-month LCR monitoring schedule at 60 sites for the July-December 2019 monitoring period.


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