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WATER SERVICE SIZING CALCULATION & JUSTIFICATION Domestic Water Service — Submitted for Site Plan Review Project 4350 Seneca Street Building Addition Location 4350 Seneca Street, West Seneca, NY 14224 (Erie County) Prepared for Havens Holding Group Prepared by Jason Havens, P.E., Principal Civil Design — NYS Lic. No. 090335 (Exp. 12/31/2026) Date July 26, 2026 Reviewing authority Town of West Seneca · Water purveyor: Erie County Water Authority 1. Purpose & Scope This calculation demonstrates that the existing one-inch (1") domestic water service is adequate to serve the proposed building addition under its intended pattern of occupancy, and documents a recommended basis for future upsizing should occupancy, demand, or funding conditions change. Scope is limited to the domestic water service (public main to the building meter/entry); interior distribution is confirmed at the plumbing permit stage, and no fire-protection demand is included (Section 8). 2. Code Basis & References ● NYS Plumbing Code (IPC-based) — §604.3 fixture flow-pressure requirements; §604.8 PRV threshold; §606.5 booster/pressure requirements. ● IPC Appendix E — segmented-loss sizing method and pressure-balance relationship; Tables E103.3(2)/(3) — WSFU load values and WSFU-to-demand conversion (Hunter's curve). ● Hazen-Williams friction relation; 8 ft/s cold-water velocity ceiling. Where purveyor standards are more restrictive than the model code, the purveyor's standards govern. 3. Existing Service & Design Criteria Parameter Value Source / note Existing service — material & size 1" copper, Type L confirmed (existing) Service internal diameter 1.025 in Type L bore Hazen-Williams C 140 copper Service developed length 90 ft (developed) incl. fitting allowance — confirmed Min. daily available pressure 67 psi purveyor / project data Static (no-flow) pressure 72 psi purveyor / project data Highest fixture above service entry 13 ft — 2nd-floor office (non- see Section 7 note governing) Water meter loss @ design flow 2.5 psi displacement meter Backflow assembly None no assembly on this service Velocity ceiling 8 ft/s cold-water service Predominant flushing system Flush tanks governs demand curve 4. Fixture Schedule & WSFU Tally Brewery fill offset. Brewery fill demand occurs within the daytime occupancy over a discrete ~45-minute fill window during which the kitchen does not operate. The brewery fill therefore directly offsets the kitchen / break- sink demand within Group A and is not additive to the group's peak fixture-unit load. Page 40 of 84