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� Page 3 Mr. Meleyco March 19, 1997 suggests that the leachfieid itself creates these conditions,and therefore a high den,.t ification ,�,te can be assumed. This is incorrect. The soil conditions may be right for denitrification at the leaching zone; however, there is no nitrate at this point - all of the nitrogen is still in the nmonia and organic forms. The deniaif�cation process can not occur until several feet below the leaching trenches, after the percolating effluent has been allowed to undergo nitrification. At this point, the conditions are no longer favorable for dentriiication, and a lower rate (e.a., to to 25%) must be assumed_ • Rainfall-Runoff and Dilution. The nitrate study done for the EIR assumed on-site retention and infiltration drainage of rainfall-runoff from the proposed deveiopme-m, which was the proposed plan for the original 39-let, 69-acre subdivision. This is an important factor in the nitrate loading analysis, since rainfall inf ftrardor. ;i.e_, groundwater re_hargc; is :lie source for dilution of the nitrate concentration in the percoladng wastewater e.tluent. The Kleinfelder study assumed approximately the same rate of rainfall-runoff infiltration for the revised 37-lot, .40-acre project as was assumed for the original project with on-site drainage retention, and did not adjust this to account for the fact that the revised project will have a drainage system that collects and discharges runoff outside of the project area. Accordingly, this result's in an overestimation of the amount of dilutionlrecharee water on the site under the developed conditions;and this adds to an t:aderestimaalt on of the projected nitrate '.oading effect on the local groundwater. The rainfall dilution factor (i.e., deep percoiado'n) should be reduced by approximately 13 to 20% (i.e., about 2 incites of runoff), as compared to the assumption used by Kleinfelder; this would properly reflect the conditions that will exist with the project. • Groundwater Flow Direction.The Kleinfelder study assumes that the flow of groundwater is to the south-southeast, away from the existing neighboring residences. This is based on a regional groundwater map, and not on any lord groundwater information in the imm-tdiate project area. This is inadequate far this type of analysis. it iti very corrLmon to find local variatdons in groundwater flow that vary from the regional trends. For instance, the existing domestic water supply wells may create a localized drawdown condi:ion. The 6roun'dwater:low needs to be investigated for local conditions in the immediate project area through a sun•ey of water level elevations at existing wells. Without this information, the safe assumption for environmental analysis is that the groundwater from beneath the project site could flow in the direction of the any of the nearby wells that border the proiect. REVISED CALCULATIONS Following are nay calculations of the predicted nitrate effects on local groundwater from the revised 37-lot, 40-acre Morada Nleadows subdivision, Nly calculations jiff-: from those in the Kleinfelder report in regard to the selection of values for :he various assumptions as discussed above. The