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+ s NLS§4:1 The_nitratelo`ading=calculions-pr-esented'demonsti ate that nitr-ate=nitrogen-.impactffom development-ofiboth Phasaserl and=Phase 2,or Phasenlusvely show the loading to'be=excessive. Only th7 e development-of thei Gas-Station=andConven enoe St5'r show marginally-acceptable nitrate nitrsgen-loading concentxati . NLS§4.2 Because of the adequate pore space characteristics of the silty, fine sandy indigenous soils, capillary action may be facilitated. Consequently, with rotational applications of effluent through a pressurized drip irrigated disposal area, along with carefully applied domestic irrigation water, the surface soils should manage an anticipated effluent flow volume through evapotrans- piration six, and possibly eight months out of the year,based upon the data presented in Table 7. In addition, nitrate-nitrogen loading may be decreased by landscape grass root uptake. It is theoretically possible that the grass groundcover may absorb most of the nitrogen in the effluent. This can be partially quantified and monitored by analyzing the nitrogen content and the volume of the mowed grass clippings over the drip irrigated disposal area. It is important the grass be medium-to-deep rooted to transpire effluent and uptake ammonium and nitrate molecules. When the grass is mowed, the clippings must not be mulched back into the thatch; clippings must be bagged and discarded. Mulching continues and completes the nitrogen cycle, and introduces additional nitrogen back into the root zone through mineralization. The higher nitrate-nitrogen concentrations observed in the soil profile near the SWC test site may be E attributable to irrigation water from several years ago flowing in an cast-to-west direction with tailwater congregating at the west end of the property. A correlation between the slow pert rates of the SWC tests and these higher nitrate-nitrogen concentrations may be made. Extensive—water.,chemistry4w;as-conducted.on the domestic well:that_currently_se-rves-fhe Kelley rresifle cn e. Arsenic was the only.const tuentTof concernthat;wasfound;to be over;the IvlCL ands tonlyLbyffppb. [Nitrate concentration wa3s'3'S ppm, which=can be_conside ed`I'gli for public=water supplies, but'still uiidef.tlie_MCLAbyaO ppm nitrate. NLS§ 2.2,3.1,3.3 Sources contributing nitrate to the underlying groundwater in this locale include indigenous soil concentrations from decomposing organic matter, lightning/rainfall,past and present upgradient agricultural fertilizer inputs, septic systems, lawn/landscape fertilization and naturally occurring geological deposits. Of these sources; however, it appears that only past and present agricultural fertilizer inputs are the predominate source contributing nitrate to the groundwater underlying the property. Factors decreasing the groundwater nitrate concentration include denitrification, groundwater movement(both vertical and horizontal),well pumping and hydraulics, and cleaner water recharge contributing to a dilution effect. j Therefore, if each of these sources and attenuating factors could be quantified on a mass balance basis, it may be that nitrate input is now roughly equivalent to output, or attenuation. Given that agricultural irrigation recharge is the largest single contributor to groundwater nitrate concentrations, and since the subject property and surrounding land has been farmed for several decades as documented by the historical photos, it would be assumed that the nitrate concentrations in the underlying groundwater should be much higher than those observed, if the attenuating factors were not significant. This is particularly evident with the soil nitrate-nitrogen test results of the sampled depths of the SWC test site. ' Page -24- Chesney Consulting i