NOVELTY - The computer device comprises a computer readable memory and a processor. The processor is in communication with the computer readable memory. The computer readable memory contains instructions. When the instructions are executed by the processor, the instructions configure to: compare an input indicating a sample result with a target for effluent gas upon receipt of the input indicating the sample result representing effluent gas from a subsurface leaching field of a sampled septic system; and provide pressure or vacuum settings for a pressure gradient system.    USE - The computer device is useful for reducing an emission of greenhouse and other gas emissions from septic systems, where the gases include carbon dioxide, methane and hydrogen sulfide to atmosphere.    ADVANTAGE - The computer device is capable of reducing the emission of greenhouse and other gas emissions from the septic systems in an effective and economic manner.    DETAILED DESCRIPTION - The computer device comprises a computer readable memory and a processor. The processor is in communication with the computer readable memory. The computer readable memory contains instructions. When the instructions are executed by the processor, the instructions configure to: compare an input indicating a sample result with a target for effluent gas upon receipt of the input indicating the sample result representing effluent gas from a subsurface leaching field of a sampled septic system; provide pressure or vacuum settings for a pressure gradient system acting on the sampled septic system; provide a schedule under which a blower or vacuum acting on the sampled leaching field is activated or deactivated; prompt for or consider the size or volume of the sampling cover in which a probe is inserted; and prompt for or consider a duration of time in which the probe is inserted into a sampling port. The input indicating the sample result is taken from the probe inserted into the sampling port of a sampling cover placed on a top of the subsurface leaching field. The input indicating the sample result with the target for effluent gas is compared: by comparing a sampled level of methane gas with a target level of methane gas: and comparing a sampled level of hydrogen sulfide gas with a target level of hydrogen sulfide gas. INDEPENDENT CLAIMS are included for:    (1) a subsurface septic system;    (2) a method of reducing discharge of septic system gases in a septic system; and    (3) a nontransitory computer readable medium.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a septic system.    Upstream wastewater source (110)    Upstream pressure gradient system (120)    Upstream input line (130)    Treatment tank (140)    Downstream pressure gradient system. (150)