Evaluation of Greenhouse Gas Emissions from Septic ... - Geoflow

Table H-8. Summary of the Water Quality Results from Site 2.ParameterRedoxDate Sample location COD (mg/L) pHpotential(mV)Dissolvedsolids (mg/L)11/05/09 ST2-1-M a - 7.24 -241 636ST2-2-M b - 7.20 -222 65211/19/09 ST2-1-M 254 6.87 -195 620ST2-2-M 173 7.06 -230 61212/08/09 ST2-1-M 240 7.02 -190 612ST2-2-M 175 7.17 -220 632Mean value c 247 7.04 -209 623Standard deviation c - 0.19 28.11 12.22Mean value d 174 7.14 -224 632Standar deviation d - 0.07 5.29 20aSeptic tank first compartment. The samples were taken one foot below the liquid surface.bSeptic tanks second compartment. The samples were taken one foot below the liquid surface.c Mean value and standard deviation from the values in the first compartment.d Mean value and standard deviation from the values in the second compartment.Water samples were also collected at both compartments of the septic tank to determinethe amount of methane, carbon dioxide and nitrous oxide present in solution. A summary of thedissolved gases calculated per compartment are presented in Table H-9.Table H-9. Summary of Dissolved Methane Measured in Each Compartment of the Septic Tank.Gas measurement (g/capita·d)Date Sample Methane Carbon dioxide Nitrous oxide11/19/09 ST2-1-L a 2.05 7.51 0.02ST2-2-L b 1.42 4.90 0.0212/08/09 ST2-1-L 1.59 4.46 0.0ST2-2-L 0.004 0.29 0.0Mean value a 1.82 6.23 0.01Mean value b 0.71 2.60 0.01a Septic tank first compartment.Septic tank second compartmentSite 2 was also selected to be sampled in detail. However, the soil infiltration system wasnot a good candidate for gas sampling due to the dense vegetation above it. Therefore, gassamples were just taken at the septic tank and vent system. Samples from the vent system weretaken at a cleanout vent located before the septic tank. The air velocity of the air in the ventingpipes varied from 30 to 80 ft.min. A summary of the GHG emission rates from the vent system ispresented in Table H-10.Evaluation of Greenhouse Gas Emissions from Septic Systems H-7