Discussion and Consideration of Change Order #2 – Tricon Construction – Tiffin Water Treatment Facility Upgrade Project – Motion to Approve — K.4

RFI To: Clint Wienen MSA Professional Services 400 Ice Harbor Drive #110 Dubuque, IA 52001 Ph: (563)582-3973 Fax: (563)582-4020 RFI #: 10 Date: 10/14/2025 Job: 25-012-IA Tiffin WTP Phone: CC: Tom Shedek (Tricon General Construction), Andy Knapp (Tricon General Construction) Subject: Chemical Containment Questions Drawing: 20A101, 20M301, 20M302 Spec Section: 03 30 00 Cost Impact: TBD pending response to RFI Schedule Impact: 0 Request: Date Required: 10/21/2025 1. Please provide the wall height for the chemical containment walls in the RO Building. 2. Please provide details as to how water stop should be applied for the chemical containment areas in the RO Building along the precast and block walls. Requested by: Betty Keuter Tricon General Construction Response: 1. By code there needs to be 110% of stored volume for containment. Wall heights we had were as follows: Caustic Soda Room (20-104)= 18" (need 550 gallons of storage) Chlorine Room (20-105) = 18" (need 550 gallons of storage) Anti-Scalant Room (20-102) = 15" (need 83 gallons of storage) The wall heights and dimensions can be adjusted as necessary for precast changes, etc. as longs as the required storage volumes are satisfied. 2. It would probably make sense to pour a 6" tall concrete curb to ensure there is not an leakage of chemical at the precast wall and CMU wall interfaces. 4" pvc waterstop would be installed in the floor slab at the concrete wall/curb interfaces. Hydrophyllic waterstop shall be installed at the vertical interfaces between the precast/CMU walls and the concrete walls. See snip below on next page for reference. Clint Wienen Answered by MSA Company October 21, 2025 Date