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Attached is a summary of the interview | had with Flint NBC 25 News late yesterday.....sorry this summary is late as | am receiving incoming calls from Flint residents... Michael Prysby, P.E. District Engineer Office of Drinking Water and Municipal Assistance 517 290-8817 xxxEND_PAGE:deq20_b01_001_057_12 Flint NBC 25 News Interview Flint TTHMs January 5, 2015 Walter-Smith Randolth, reporter, from Flint NBC 25 News conducted a telephone interview with me for broadcast on Flint local television concerning the TTHM violation in Flint’s drinking water. I led the interview and provided Mr. Randolth an opportunity for follow-up questions. Below is a summary of topics that were presented. TTHM violation — What does this mean for Flint residents? The TTHM violation notice to residents is not an immediate public health emergency since the health-effects posted in the notice require long- term exposure to TTHMs (over a significant portion of an individual’s lifespan). TTHMs commonly occur in public water systems that disinfect with chorine due to the reaction between chlorine and naturally occurring organic compounds (total organic carbon) in the source water. Surface water sources, including the Flint River watershed, typically have higher levels of naturally occurring organic compounds. What is the DEQ’s Role? The DEQ is working in collaboration with the city to ensure long-term public health protection and to keep the public informed. We are working with the city to help identify improvements in treatment and operation of the distribution system to reduce the levels of TTHMs. We are assisting the city with public notice requirements (when to post/contents). With our assistance, the city has proceeded with an operational evaluation of the water system ahead of state and federal requirements. DEQ’s perspective of the situation: _ The Flint River source is more difficult to treat since it requires more disinfection to maintain bacteriological intergrity. Increased disinfection; however, when combined with higher levels of naturally occurring organics results in elevated levels of TTHMs that form over time out in the distribution system. The TTHM concentrations that developed in the system were more than anticipated due to several reasons: 1. Flint did not immediately change their mode of distribution system operation after switching sources to account for higher TTHM formation potential of treated water from Flint’s WTP. xxxEND_PAGE:deq20_b01_001_057_13 T explained that TTHMs require time to form and are not fully developed in the treated water that enters the distribution system from the WTP. Water from Detroit; however, is several days old when it reaches Flint; thus the majority of the TTHMs are developed. TTHMs were also lower given the source water (Lake Huron). Flint’s historically operated the distribution system in a manner that created conditions favorable for stagnation. This methodology of operation was not changed (initially) when switching to the Flint River; thus, this condition was one of several factors contributing to higher levels of TTHMs. Other factors included; higher TTHM formation potential in the Flint River (already explained above) and higher chlorine application rates at treatment plant to maintain bacteriological integrity. I further explained that TTHM levels in the most recent quarter have dropped for two main reasons: 1. Action taken by the city including; improving dist. system operation to reduce stagnation, treatment changes (complete softening), reduced chorination, system flushing, valving improvements 2. Seasonal fluctuation of organic compounds in the Flint River. Less organic loading in the winter months. END of MY DISCUSSION Mr. Smith-Randolf asked for my comment to the following this problem is occurring in Flint? Is there a problem with the water system? This was not an issue when Flint was on Detroit water. I responded by summarizing some of the key points discussed above including: Dist system operation (storage facilities and valving) TTHM formation potential in Flint River vs. Detroit and age of incoming water e High chlorine dosages to maintain bacteriological integrity e Treatment practices at WTP (partial by-pass of softening) xxxEND_PAGE:deq20_b01_001_057_14