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r7Thiss exactly what is being calculated on Page 8 of my report for the value of"I"! For example:I do an irrigation analysis for a farmer and she/he tells me they applied"36 inches last yr," she/he is referring to the height of irrigation water applied over their irrigated acres, which is easily calculated to a volume. This acre-feet/yr volume is the same volume as cu ft/yr in the equation to determine"the rate of wastewater entering the soil averaged over the gross developed area in inches per yr."Again: the numerator determines the total wastewater discharged per year in cubic feet, or could be in an equivalent volume in ac ft; cu ft are used to arrive at the units of in/yr. The denominator is determining the area. Using the numbers in the equation on Page 8,we find the following: There are 325,851 gallons in an ac-ft. Total wastewater generated was estimated to be 971,712 gals/yr or 129, 908 cu ft/yr; both are the same volume as 2.982 ac-ft/yr. We now have an equivalent ac-ft volume in the numerator, but area has to be determined in the denominator,which is equivalent to "gross developed area"or the same as "irrigated acreage." Now we have the area in sq ft in the denominator and the calculation follows with units canceling: 2.982 ac-ft/yr= 129,908 cu ft/yr = 1.157 in/yr 30.94 Ac x 43,560 sq ft/Ac= 129,896 sq ft x 0.0833 (1 ft/12 inches) The author of Attachment 1 then goes into a rainfall analysis that is incredible overkill for such an inexact science as nitrate loading. It is an inexact science because of the number of unknowns that cannot be accurately quantified and are continually changing. These unknowns should be easily recognizable by anyone with just a cursory knowledge of nitrate loading, and they total to well over a dozen. When there is this many unknowns or variables, variability is superimposed over variability, leading to greater variability! The author goes into great detail about the role a retention basin would contribute to the nitrate loading assessment, but then fails to recognize and make a judgement analysis about what contribution a retention basin would make as a dilution factor to the resultant wastewater recharge, which is readily discussed in the scientific literature. The author apparently also fails to recognize that rainfall volumes can actually be beneficial in mitigating nitrate loading by forcing denitrification in certain soils. My reports go into great detail addressing and discussing the vast majority of the variables that exist in a nitrate loading analysis. I work with assessing and quantifying nitrogen in the soil and groundwater environments almost on a daily basis and I see these variables involved. The fact remains that there are a number of viable methods to calculate, or rather guesstimate, nitrate loading from a project. a4tofessio4 Respectfully submitted, � or v �hes�� CHESNEY CONSULTING 4 � r• No.7.,s479 a * `ar Civil Don Ches ey, PE/CC7er e°f Califos� Registered Civil Engi75479 Certified Crop Advisor/CA Registered Nitrogen Management Specialist 4341829 Page 2 of 3 Chesney Consulting