CITY COUNCIL REGULAR MEETING AGENDA PACKET 4-21-26

Page 2 of 3 exceedance, staff coordinated with the DDW, which resulted in the issuance of DDW Citation and Compliance Order No. 02 02 25J 001 (Order) on September 9, 2025. The Order required notification to affected customers and the preparation of a Corrective Action Plan and an Operational Evaluation Report (CAP/OER). The CAP/OER was submitted to DDW in November 2025 and approved in March 2026. The CAP/OER identified several factors contributing to elevated DBPs, including: • Source Water Blend: Increased surface water from Zone 7 with high organic content in early 2025, combined with a limited groundwater supply due to the loss of City groundwater wells (normally low in organic content), resulted in higher DBP precursors entering the Kilkare system. • Disinfection Practices: Disinfection by breakpoint chlorination at Kilkare is necessary to prevent nitrification; however, this method can accelerate DBP formation under high- organic conditions. • Distribution System Characteristics: The Kilkare service area has long water residence times due to low customer demands and lengthy runs of piping, with multiple tanks and booster stations required to deliver water to customers at high elevations. Long water residence times during warm weather periods increase DBP formation. • Limited Control and Predictive Information: The City currently lacks access to real- time data on Zone 7 source water quality and has no active local supply to offset source water changes. To address these challenges, the CAP/OER identified immediate actions, short-term actions, and a feasibility study for long-term solutions focused on reducing water age, optimizing source water blends, maintaining disinfectant residuals, and improving monitoring and coordination with Zone 7. The City’s immediate actions have reduced the LRAA for TTHMs and HAA5 at monitoring location S-31 below the MCLs, with Q4 2025 calculated values of 0.079mg/L and 0.058 mg/L, respectively. Short-term actions and the feasibility study for long- term solutions are currently underway, with required completion dates of June 2026 and December 2026, respectively. DISCUSSION The City’s existing agreement with Carollo provides professional services in support of the Water System Management Plan (WSMP), including identifying and implementing water quality improvements. This agreement was used to have Carollo prepare the CAP/OER in response to the DDW order. Additional support from Carollo is needed to implement the actions identified in the CAP/OER. Services include developing standard operating procedures for DBP management, conducting hydraulic modeling to identify opportunities to reduce water age and improve source blending, and conducting a feasibility study to evaluate long-term disinfection practices and DBP control measures. The Third Amendment increases the agreement compensation amount by $75,000 to perform these time-sensitive, compliance-driven services. Because the services are required to meet regulatory deadlines in order to continue delivering water services to the Kilkare area, the amendment was executed, and staff are now seeking formal ratification by the City Council. Page 230 of 846