Important EIA formulas

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Formulas that need to be mastered well: I. Atmospheric section: 1. Formula for calculating equivalent emission volume: (refer to P33) (m3/h). Qi – Emission volume per unit time, t/h； Remember that 2.5×108 and ≥2.5×109 are the boundaries. The upper limit is used for flat areas, while the lower limit is used for complex terrains. 2. Source strength calculation formulas: (Tech P38, Tech P125) QSO2 = G×2×0.8×S×(1-ηs); Q_dust = G•A•ηA ×(1-η); Qi (kg/h) = QN•Ci×10-6. QN is the volume flow rate of waste gas, in m3/h ； (Standard air volume for exhaust fans) 3. Formula for the lift height: in windy, neutral, and unstable conditions (1) When Qh ≥ 21,000 KJ/s and ΔT ≥ 35 K: Urban and hilly areas (cities and their surrounding suburbs): Qh = 0.35PaQvΔT/Ts; Plain rural areas (rural regions or areas far from cities): (2) When 2,100 KJ/s ≤ Qh ≤ 21,000 KJ/s and ΔT ≥ 35 K: Urban and hilly areas (cities and their surrounding suburbs); Plain rural areas (rural regions or areas far from cities): (3) When Qh < 2,100 KJ/s or ΔT < 35 K: 4. Formula for the concentration along the downwind axis of pollution sources: He – effective height of the exhaust stack. He = H + ΔH; Q is the emission rate per unit time, in mg/s ； U—Average wind speed at the exhaust stack outlet, m/s ； P—divided into urban and rural areas; E and F belong to the same category. σy—is the horizontal lateral diffusion parameter perpendicular to the average wind direction, in m ； σz—vertical diffusion parameter, m ； σy = γ1Xα1, σz = γ2Xα2 for a sampling time of 0.5 hours. σy1 = σy0.5(τ1/τ0.5)q Time correction. At 1 hour, set q to 0.3. α1——Regression exponent of the lateral diffusion parameter ； α2——regression exponent of the vertical diffusion parameter ； γ1——regression exponent of the lateral diffusion parameter ； γ2——regression exponent of the vertical diffusion parameter ； X — Horizontal distance downwind from the exhaust stack. 5. Vertical temperature lapse rate: γγd, unstable ； When γ=γd, it is neutral. II. Surface water section: 1. Formula for the length of the mixing process section: B—river width ； H—average water depth ； u— average river flow velocity in m/s ； g—acceleration due to gravity, 9.81m/s2 ； I—river slope, m/m. 2. Complete mixing mode (zero-state mode) 3. One-state mode K1—oxygen consumption coefficient ； K3—settling coefficient. K1 + K3 = K, which is the attenuation coefficient. 4. S-P mode III. Noise section: 1. Sound pressure level: LP = 20lgP/P0. 2. Addition of sound levels (in decibels): based on energy (sound power or square of sound pressure). When several sound pressure levels are all LP, … 3. Attenuation due to a point sound source: The attenuation at distances r1 to r2 from a point sound source is given by ΔL1 = 20 lg r1/r2. When r2 = 2r1, ΔL1 = -6 dB. 4. Attenuation due to a line sound source: The attenuation at distances r1 to r2 from a line sound source is given by ΔL1 = 10 lg r1/r2. When r2 = 2r1, ΔL1 = -3 dB