Successful Strategies for Control of DBp Formation in Arkansas Callie Acuff, E.I. SWAWWA Annual Conference - Baton Rouge, LA October 29, 2018

My Background Graduated from the University of Arkansas with a B.S. in Biological Engineering and a minor in Sustainability Almost 1.5 years with ADH as the DBP Technical Support Engineer

DBPs in Arkansas Arkansas has 1059 public water systems 436 surface or surface purchasing systems 623 groundwater or groundwater purchasing systems Two main regulated DBPs: TTHMs and HAA5 THMs tend to be more prevalent than HAAs across the state All DBPs in surface systems tend to be chlorinated Groundwater systems with DBP issues typically have brominated THM formation [– natural bromide occurrence in Southern Arkansas]

Distribution of Surface Water vs. Groundwater Sources in Arkansas Mention springs and GWUDI wells

Background about ADH and their DBP Involvement Historically ADH has a strong, proactive program dealing with DBP issues around the state Participation in EPA AWOP (Area Wide Optimization Program) for many years – DBPs are one of the focuses of this program 2017-2018 Quarterly Meetings Focus – DBP Optimization Strategies Program has allowed for exchange of ideas and strategies between professionals in the industry in different states. ADH has a history of proactivity when it comes to DBP issues among public water systems.

Stage 2 DBP Violations in the United States, FY 2017

DBP Formation Contributors Disinfectant Type Chlorine Chloramines Chlorine Dioxide Ozone Disinfectant Dose/Residual Primary Secondary DBP Precursors Amount of TOC Type of TOC Often unknown Bromide Temperature Time pH On this slide are some of the factors that contribute to DBP formation. [First, disinfecting your water will contribute to DBPs, but you have to do it. It’s unavoidable.] The type of disinfectant also affects what DBPs are formed and the amount that is formed. Using free chlorine to disinfect leads to the most THMs and HAAs, but it also *gives the most credit for CT and can be used on its own.* Chloramines don’t generally form DBPs but also *don’t provide a strong enough residual to be used as a primary disinfectant.* However, if DBP formation within the plant can be kept at a minimum, chloramines can be used in the distribution system to limit or even stop further formation. As previously mentioned, chlorine dioxide and ozone form specific DBPs, but they *generally don’t contribute to THM and HAA formation.* *look into what credit ozone and chlorine dioxide get towards CT* Also, the amount of disinfectant and the residual can contribute to DBP formation. This mainly pertains to free chlorine. Dosing a high amount of chlorine on the front end can cause a DBP spike within your plant, and keeping a high residual in distribution can cause further DBP formation. DBP precursors are the other necessary ingredient to create DBPs. We use total organic carbon, or TOC, as an indicator for the amount of precursors in raw surface water. TOC is only monitored for surface water. The required amount of TOC that must be removed depends on *the initial concentration and the alkalinity of the raw water.* There are certain fractions of TOC that specifically cause DBP formation, but TOC cannot be easily separated into its fractions and most systems do not have the capacity to do so. Bromide reacts with chlorine to form hypobromous acid and then with Natural Organic Matter to form the brominated species of THMs. Temperature - Higher temperatures speed up the reaction mechanism that forms DBPs, allowing more to form. Time – if left unchecked, DBPs will continue to form as long as there as a residual present in the water pH – higher pH typically results in higher THMs, and it is thought that a lower pH can result in higher HAA formation * - check We use TOC as an indicator for NOM. As temperature raises so does the THM formation rate As time continues, so does the reaction that is creating the THMs Higher pH results in higher THMs Throughout this talk we will try to identify strategies to minimize DBP concentrations based on our knowledge of how these factors contribute to DBPs

DBP Formation Contributors Control by Wholesale System Control by Consecutive System TOC Yes Limited – Biofilm Chlorine Dose Sometimes Chlorine Residual Time pH No Temperature

ADH Technical Assistance Endeavors

Brinkley Waterworks Groundwater System Had experienced DBP issues in the past Treatment is Aeration Clarification Filtration Clearwell Chloramination System started to experience high levels again

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks

Brinkley Waterworks Advised that the majority of the DBPs were being formed in the clarifier, and that chlorine should be limited there System took appropriate action by: Limiting chlorine in clarifier Utilizing another oxidant for the manganese removal they were seeking Following data was collected one week later.

Brinkley Waterworks

Brinkley Waterworks

Mayflower Waterworks System is at the end of a very long transmission line from a wholesaler System had experienced DBPs at elevated levels The master meter for the system is on the same site as 2 tanks.

Mayflower Waterworks Forced draft aeration installed.

Mayflower Waterworks

Booneville Waterworks Sample site was at the concession stand at the baseball field. The concession stand is only open in the summer time during baseball season. The service line from the main to the concession stand needed 30 minutes to flush at 2 gpm. The main serves other customers in the area.

Booneville Waterworks Sampling station installed at the point where the service line meets the main. Results: 1st Qtr TTHM results changed from 97 ppb in 2008 to 47 ppb in 2010.

USCOE OC Buckville Sample site is in a fishing community with low demand on weekdays. The community is fed by a standpipe which is controlled by an altitude valve. The tank only fluctuated 1.5 feet.

USCOE OC Buckville Before Flush Valve: Analysis: July 22-30, 2010 Average Operation Range: 51 ft – 49.5 ft Theoretical Days of Storage: 49.4 days After Flush Valve Installed: Analysis: Sept. 24, 2010 – Oct. 05, 2010 Average Operation Range: 52 ft – 32.5 ft Theoretical Days of Storage: 5.5 days

Hope W&L (SAWS, Bodcaw) System with surface and groundwater sources Separate treatment facilities for the different sources Parent system gets violations at one sample site Site receives mostly surface water Other sites mostly supplied by ground water and don’t have compliance issues Two of three consecutive systems also regularly have compliance issues These consecutives receive water from the largely-surface water side of the system.

Dichlorobromo-methane Dibromochloro-methane % Bromoform/ Groundwater Hope W&L (SAWS, BODCAW) To confirm that Hope’s surface and groundwater sources differed in water quality, ADH analyzed the compliance sample deviation. Site Chloroform Bromoform Dichlorobromo-methane Dibromochloro-methane TTHM % Bromoform/ Groundwater 230YD004 1.18 40.1 2.57 11.2 55.05 72.84% 230YD025 75.3 13.7 2.53 91.53 0.00% 230YD026 7.71 1.32 3.85 12.88 59.86% 230YD034 0.81 61.5 2.1 12 76.41 80.49%

Hope W&L (SAWS, Bodcaw) Once it was confirmed that Hope’s two sources had different DBP formation potentials, ADH recommended that Hope utilize their groundwater sources as much as possible and minimize use of their surface water source. Hope formed an action plan to limit their use of surface water; however, the site with compliance issues was still receiving mostly surface water because of the system’s configuration and still having compliance issues.

Hope W&L (SAWS, BODCAW) Hope looked into a number of treatment solutions Pre-oxidation: ClO2 was added as a pre-oxidant to limit the use of Cl2 gas Alum dose was optimized through jar testing These solutions still weren’t enough to keep Hope and its consecutives in compliance System decided to do some capital improvements to their plant Clearwell improvements, added aeration to treatment process. These improvements are currently underway.

Des Arc Waterworks Groundwater system Has consistently had DBP issues for years Treatment: Aeration Disinfection Clarification Recarbonation Filtration

Des Arc Waterworks Source water is a combination of raw water from four different wells Three of the wells pull from the Alluvial Aquifer One pulls from the Sparta Aquifer Water is blended together at the plant pre-treatment ADH performed hold study to determine how much each source well varied in quality

Des Arc Waterworks

DES Arc Waterworks

Certified Lab Results (ppb) Des Arc Waterworks Hold Study Results Certified Lab Results (ppb) Date 7/20/17 7/21/17 7/24/17 7/24/17a 7/25/17 Time 3:30 PM 11:45 AM 3:45 PM 10:15 AM 10:15 AMa 4:10 PM 3:00 PM Well 2 Cl2 2.91 1.44 1.77 0.6 -- 0.54 0.96 93.4 THM+ 59 109 N/Ab Well 3 1.86 0.75 0.84 0.21 0.06 0.03 74.8 52 98 136 Well 4 2.7 1.32 1.83 1.08 1.11 1.17 75.1 133 72 Well 5 2.01 0.66 0.87 0.42 0.63 0.78 163 45 131 Notes: a THM+ results were measured twice due to a discrepancy with the blanks. One blank was much lighter than the other (-43 ppb difference). Lighter blank results are displayed second column with the same time stamp. b No THM+ result for well 2 read against the lighter blank because of experimenter error.

Chlorine Consumed During Study Speciation of Des Arc THM Results Des Arc Waterworks Chlorine Consumed During Study Well Initial Cl2 Residual (ppm) Final Cl2 Residual (ppm) Cl2 Consumed (ppm) Well 2 2.91 0.96 1.95 Well 3 1.86 0.03 1.83 Well 4 2.7 1.17 1.53 Well 5 2.01 0.78 1.23 Speciation of Des Arc THM Results Wells Bromoform (ppb) DBCM (ppb) DCBM (ppb) Chloroform (ppb) %chlorinated species %brominated species Well 2 ~0 4.9 20.8 67.7 94.8% 5.2% Well 3 4.0 16.3 54.5 94.7% 5.3% Well 4 7.1 21.4 46.6 90.5% 9.5% Well 5 96.0 49.7 13.4 3.8 10.6% 89.4%

Des Arc Waterworks Based on speciation of the certified lab samples, ADH recommended that Des Arc Waterworks utilize Wells 2-4 over Well 5 DBP levels went from the 90-110 ppb range in 2017 to the 60-75 ppb range in 2018

Callie Acuff, E.I. 501-661-2672 callie.acuff@arkansas.gov Questions? Callie Acuff, E.I. 501-661-2672 callie.acuff@arkansas.gov