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An Ohio Corrosion Control Case Study
Citation:
Lytle, D., M. Schock, AND C. Formal. An Ohio Corrosion Control Case Study. 15th annual EPA Drinking Water Workshop: Small Systems Challenges and Solutions, Covington, KY, August 28 - 30, 2018.
Impact/Purpose:
To facilitate the development of an area-wide optimization program within the participating states and EPA. EPA procedure requires no intentional flushing before 6 hour stagnation. Corrosion Control Treatment: (1) Prior 2010, caustic feed and calcium carbonate saturation state (Marble test). (2) Had not exceeded AL so corrosion control not formally established. (3) Lead AL exceedance in late 2015. (4) Resumed caustic soda (NaOH) feed in January, 2016. (5) Raise pH. PWSs with LSLs should have optimized corrosion control treatment in terms of minimizing Pb release and exposure. Corrosion Control Treatment: Began feeding orthophosphate in March, 2016. Initial goal (OEPA Order): pH > 7.2 (> 7.5 preferred) Initial goal (OEPA Order): > 2 mg PO4/LGoal pH: 7.2-7.7 (Prefer 7.5-7.7)Goal orthophosphate: 3±0.3 mg/L. Sequential Sampling: Series of samples taken after stagnation, First samples typically 125-250 mL Later samples 1 L (uniform plumbing, Correlate sample volumes to plumbing sections, Useful for identifying lead sources and remedial actions-flushing & plumbing replacements, Captures lead peaks from LSL or other plumbing that a 1 L sample may miss, Requires a large number of samples-time and cost intensive, More complicated to produce an Action Level or interpretation standard, and Fluctuate feed depending on season Goal Chlorine: 1.2-1.5. Required by OEPA Eighteen different homes in sampling pool, 5 to 8 homes sampled on a monthly basis for 25 months +, Many homes dropped out of pool, Non-LSL homes, LSL removed, Home vacant 2-125 mL samples followed by 1 L samples depending on on-site plumbing assessment, and Lead, copper and zinc measured. Conclusions: Medium-sized community water system with fluctuating source water exceeded lead action level (pH adjustment). Orthophosphate addition (3 mg PO4/L goal) and pH adjustment (7.5 goal) were implemented Jar testing was used to screen for unintended consequences (precipitation of phosphates). Sequential sampling (and LCR sampling) was used to assess overall corrosion control progress with time. Seasonal fluctuations in lead were observed. Lead levels decreased with time Unintended consequences of orthophosphate treatment were not observed
Description:
Presentation on lead at the 15th Annual EPA Drinking Water Workshop: Small Systems Challenges and Solutions. To facilitate the development of an area-wide optimization program within the participating states and EPA. EPA procedure requires no intentional flushing before 6 hour stagnation. Corrosion Control Treatment: (1) Prior 2010, caustic feed and calcium carbonate saturation state (Marble test). (2) Had not exceeded AL so corrosion control not formally established. (3) Lead AL exceedance in late 2015. (4) Resumed caustic soda (NaOH) feed in January, 2016. (5) Raise pH. PWSs with LSLs should have optimized corrosion control treatment in terms of minimizing Pb release and exposure. Corrosion Control Treatment: Began feeding orthophosphate in March, 2016. Initial goal (OEPA Order): pH > 7.2 (> 7.5 preferred) Initial goal (OEPA Order): > 2 mg PO4/LGoal pH: 7.2-7.7 (Prefer 7.5-7.7)Goal orthophosphate: 3±0.3 mg/L. Sequential Sampling: Series of samples taken after stagnation, First samples typically 125-250 mL Later samples 1 L (uniform plumbing, Correlate sample volumes to plumbing sections, Useful for identifying lead sources and remedial actions-flushing & plumbing replacements, Captures lead peaks from LSL or other plumbing that a 1 L sample may miss, Requires a large number of samples-time and cost intensive, More complicated to produce an Action Level or interpretation standard, and Fluctuate feed depending on season Goal Chlorine: 1.2-1.5. Required by OEPA Eighteen different homes in sampling pool, 5 to 8 homes sampled on a monthly basis for 25 months +, Many homes dropped out of pool, Non-LSL homes, LSL removed, Home vacant 2-125 mL samples followed by 1 L samples depending on on-site plumbing assessment, and Lead, copper and zinc measured. Conclusions: Medium-sized community water system with fluctuating source water exceeded lead action level (pH adjustment). Orthophosphate addition (3 mg PO4/L goal) and pH adjustment (7.5 goal) were implemented Jar testing was used to screen for unintended consequences (precipitation of phosphates). Sequential sampling (and LCR sampling) was used to assess overall corrosion control progress with time. Seasonal fluctuations in lead were observed. Lead levels decreased with time Unintended consequences of orthophosphate treatment were not observed