Leachate Generation from a Water Balance
Turns precipitation, runoff, and evapotranspiration into leachate per year, per day, and per open acre.
Example
You enter
- Open cell area (acres) 20
- Annual precipitation (in) 40
- Runoff coefficient 0.15
- Evapotranspiration coefficient 0.3
- Capped-area infiltration (in/yr) 2
- Design storm depth (in) 2
You get
- Infiltration 22.0 in/yr over 871,200 sq ft
- Leachate generated 11,947,886 gal/yr (32,734 gpd)
- Leachate (GPD) 32733.9
- Per open acre 1636.7
- Capped, same area 1,086,171 gal/yr (2,976 gpd) -- 91% less
- Capped (GPD) 2975.81
- Capping reduction (%) 90.9091
- The design storm 597394
- Storm days of average 18.25
Checked against published worked examples from: Oklahoma Cooperative Extension Service, Oklahoma State University.
Details, formula, and sources
ScopeAgainst the same area capped and against a design storm. The worked 20 acre cell makes 1,637 gpd per open acre and 91% less once capped; one storm delivers 18 days of average flow.
Formula or tableinfiltration = precipitation x (1 - runoff coefficient - evapotranspiration coefficient); leachate volume = infiltration depth x area, at 7.48 gallons per cubic foot.
Source and editionA screening water balance. HELP modelling, the site's own leachate records, and the permit's storage and treatment requirements govern.
Free accessPublic arithmetic; HELP is published by the EPA and is freely available.
What governsEstimate. AHJ and licensed professional govern.
API field namesopen_acres, annual_precip_in, runoff_coefficient, evapotranspiration_coefficient, capped_infiltration_in_per_year, design_storm_in, infiltration_in_per_year, leachate_gal_per_year, leachate_gpd, gpd_per_acre, capped_gal_per_year, capped_gpd, capping_reduction_pct, storm_volume_gal, storm_days_of_average
- Coefficients entered; runoff and evapotranspiration are site and cover specificsite records / HELP
- Scope infiltration only; it does not model the liner, the collection system, or recirculationspec-v1791 scope
- Annual lump one annual balance with no soil-moisture storage term. The Fenn (EPA SW-168, 1975) method runs month by month and percolates only once the cover soil is at field capacity, so an annual lump reads high where rain and evapotranspiration peak in different seasons: Vesilind Table 13-2 prints 213 mm for Cincinnati where the annual lump gives 303 mm, and 70 mm for Orlando against 76 mmVesilind, Worrell & Reinhart, Environmental Engineering (2003), Table 13-2