Metcalf & Eddy Wastewater Engineering (5th Ed.) / CPHEEO Manual on Sewerage & Sewage Treatment

ETP Screening & Equalization Tank Sizing Calculator

Peak flow hydraulics, Kirschmer bar screen headloss, equalization storage volume, SWD basin dimensions & air mixing blower capacity

ETP Screening & Equalization Tank Sizing Calculator Process & Field Engineering Reference
Engineering Process Reference: ETP Screening & Equalization Tank Sizing Calculator governing plant layout conforming to Metcalf & Eddy Wastewater Engineering (5th Ed.) / CPHEEO Manual on Sewerage & Sewage Treatment.

1. Engineering Principles & Mathematical Formulation

Engineered sizing model for Effluent Treatment Plant (ETP) raw inlet works. Calculates bar screen approach & through velocities and hydraulic head loss using Kirschmer’s equation, computes equalization tank liquid volume with safety freeboard buffer margins, determines tank geometry (SWD, Length, Width), and calculates coarse air mixing blower capacity to prevent solids deposition and septic anaerobic odor release.

This calculation engine executes rigorous mass-balance and hydraulic equations. Every parameter is cross-checked to ensure zero rounding drift across bidirectional US Imperial and SI Metric unit systems.

2. Governing Standards & Authoritative Citations

"Design calculations for municipal and industrial water infrastructure must strictly adhere to recognized empirical standards to ensure hydraulic stability, structural integrity, and environmental compliance."
— Metcalf & Eddy Wastewater Engineering (5th Ed.) / CPHEEO Manual on Sewerage & Sewage Treatment, American Water Works Association (AWWA) & U.S. Environmental Protection Agency (EPA Manual 832-B-99-002)

Primary benchmark citations include Crane Technical Paper No. 410, ASME Section VIII, and Metcalf & Eddy Wastewater Engineering.

3. Required Input Parameters & Variables

Symbol: Q_daily

Daily Wastewater Flow

Default: 500 (GPD)
Symbol: T_op

Operating Discharge Hours per Day

Default: 16 (hr/day)
Symbol: K_peak

Peak Flow Factor

Default: 2 (ratio)
Symbol: HRT

Target HRT in Equalization Tank

Default: 10 (hours)
Symbol: Buffer%

Tank Volume Buffer & Freeboard

Default: 20 (%)
Symbol: R_air

Air Mixing Rate per Tank Volume

Default: 1.5 (CFM/ft³·h)
Symbol: SWD

Side Water Depth (SWD)

Default: 3.5 (ft)
Symbol: L:W

Tank Length-to-Width Ratio

Default: 1.5 (ratio)
Symbol: b

Bar Screen Clear Opening

Default: 10 (in)
Symbol: w

Screen Bar Thickness

Default: 6 (in)
Symbol: β

Bar Cross-Section Shape Factor

Default: 2.42 (factor)
Symbol: θ

Screen Incline Angle to Horizontal

Default: 75 (deg)
Symbol: W_c

Inlet Screen Channel Width

Default: 0.6 (ft)
Symbol: d_c

Channel Water Operating Depth

Default: 0.5 (ft)
Symbol: Clog%

Screen Clogging Factor

Default: 30 (%)

4. Professional Engineer (PE) Submittal Workflow

WaterCalcStudio Pro generates timestamped PDF calculation reports complete with formula proofs, intermediate variable breakdowns, and signature review blocks suitable for regulatory submittals.