An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

HELP 4.0 User Manual

User manual for the Hydrologic Evaluation of Landfill Performance (HELP) model 4.0

HELP is a quasi-two-dimensional hydrologic model of water movement across, into, through and out of landfills. The model accepts weather, soil, and design data. It uses solution techniques that account for key factors affecting water movement in a landfill, including: surface storage; snowmelt; runoff; infiltration; evapotranspiration; vegetative growth; soil moisture storage; lateral subsurface drainage; leachate recirculation; unsaturated vertical drainage; and leakage through soil, geomembrane, and composite liners. Landfill systems including various combinations of vegetation, cover soils, waste cells, lateral drain layers, low permeability barrier soils, and synthetic geomembrane liners may be modeled. The model was developed to conduct water balance analysis of landfills, cover systems, and solid waste disposal and containment facilities.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.