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4. Methodology and References Sanitary demand is estimated from occupant load using unit design-flow rates consistent with the Recommended Standards for Wastewater Facilities (Ten State Standards) and the NYS Design Standards for Intermediate Sized Wastewater Treatment Systems. Sewer hydraulic capacity is computed with Manning’s equation. 4.1 Average and peak demand ADF = Σ ( unit flow rate × occupancy ) Peak = ADF × PF A peak factor (PF) of 4.0 is applied to the small demand, consistent with the Ten State peaking curve for low tributary populations. 4.2 Sewer hydraulic capacity Qₘₐₓ = (1.49 / n) × A × R2/3 × S1/2 Capacities below use the code / standard minimum design slope for each pipe as a conservative basis, so no field slope data is required; actual capacity is greater. n = 0.013 (PVC service); n = 0.011 (lined 15″ main). 5. Sanitary Demand (Occupant Load) Representative unit rates: employees 20 gpd each; guests 10 gpd each. Occupancy per applicant; unchanged by the proposed addition. The second-floor office serves existing staff and adds no occupant load. Source Rate Qty ADF (gpd) Employees 20 gpd/emp 4 80 Guests / patrons 10 gpd/guest 65 650 Average daily demand (ADF) 730 Peak demand (PF = 4.0) 2,920 gpd ≈ 2.0 gpm Existing and proposed demand are identical (≈ 730 gpd average / ≈ 2.0 gpm peak). The addition produces no increase in sanitary demand. Conversions: 1 gpm = 1,440 gpd; 1 cfs = 448.8 gpm. Sanitary Sewer Capacity Analysis • 4350 Seneca Street Building Addition • Page 3 Page 46 of 84