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v s From the original Nitrate Loading Study completed for the subject property in February 2003, the property has an a roximate c pp arrying capacity of 300 people. This must be considered as expansion takes place. As noted however, Lathrop City water and sewer are projected to reach the property in five to 10 years. With regard to the calculated nitrate-nitrogen loading to the underlying groundwater table, it is important to recognize that when adding one concentration of a solute (e.g.,NO3 N concentration determined in the effluent recharge) to another concentration of a solute (e.g.,NO3-N concentration determined in groundwater table), where both solutes are in ppm,the result is not cumulative or the sum of the two solutes. Parts per million is a mass ratio (mg per106 mg). For example,the Nr(the resultant average concentration of nitrate-nitrogen in effluent recharge in ppm of NO3-N), was determined to be 1.9 ppm by the Hantzsche-Finnemore Equation. This equals 1.9 milligrams of nitrate in 106 milligrams of water(one liter). If this 1.9 ppm concentration is added to the same volume of water(1 x 106 milligrams) of the concentration determined in the underlying ELF water table, which was 35.1 ppm NO3 N(156 ppm NO3),then the resultant concentration is now: 1.9 milligrams per liter+ 35.1 milligrams per liter= 37 milligrams in 2 x 106 milligrams(2 liters, or parts per 2 million) of water. Therefore, to convert back to ppm, the numerator and denominator must be divided by 2 with the result of 18.5 milligrams NO3 N per 1 x 106 milligrams, or 82.3 ppm nitrate NO3. Therefore, the mixing layer located at the top of the first aquifer consisting of recharge effluent and existing phreatic groundwater theoretically will undergo a dilution effect from the percolating effluent. At one point in time, there were four wells on the subject property. At present, only one well is observable,which is located adjacent to the west of the Office Trailers. The other wells are presumed to have been destroyed, although no well destruction permits are on file at EHD. If a well is subsequently discovered, Preston Pipelines must obtain a well destruction, or an out-of-service EHD permit for that well. RECOMMENDATIONS AND MAINTENANCE A maintenance program must be established for the entire wastewater disposal system. However, this cannot be accurately assessed, quantified and implemented until the project is completely built-out and fully occupied. As referenced,predicting septic tank pump-out intervals is impossible because it is unknown as to the number of people on-site at any given time, and the composition of influent. Both these unknowns lead to changes in the quantity, quality and operational parameters of the proposed septic system. Because of the proposed showers and kitchenibreak-room area with a dishwasher, effluent characteristics may be similar to domestic sources instead of commercial sources. Because of potential dilution effect, the nitrogen content of the effluent may be lower than used in the calculations. It is anticipated to have the ELF tanks pumped yearly,or analyzing the scum and sludge thicknesses after a year of operation. When the first tank contents are pumped, one-third of the tank contents should remain in the tank for ballast. i 22 Chesney Consulting