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The proposed guard house will contain the restroom, consisting of a toilet and sink. It is my understanding that this will be the only wastewater fixture units on the developed property. Although the restroom is obviously for the use by the guards, according to EHD standards, people who are associated with a facility, whether they are employees are not, must have access to available restroom facilities. The day workers at offices are assigned 30 gallons per person per day per EHD Sewage Standards, which is extremely exorbitant and based on antiquated plumbing fixtures. Transient truck drivers cannot be considered office workers. There will be parking for a maximum of 41 trucks per the Application Referral, and therefore 41 drivers,who may potentially use the restroom at the beginning and end of each shift. Taking a reasonable usage factor of five gallons per day for each driver(2.5 gals AM, 2.5 gals PM), we find i 42 people (includes guard) x 5 gallons = 210 gpd. Total usage— 10 gpd x 5 days per week= 1,050 gpw x 50 wks per yr= 52,500 gpy. Wastewater Characteristics Blackwater will originate from toilets and graywater from hand washing. Additional wastewater constituents may consist of other liquids to the system, such as coffee,juices, etc. Industrial or commercial chemicals, solvents, etc. must not be introduced into the wastewater treatment system. The scientific literature cites nitrogen concentrations in domestic septic effluent typically ranging from 17 mg N/L for graywater basins, sinks, etc. to 140 mg N/L for blackwater toilet wastes. Therefore, considering a 38/52 percent usage for toilet and hand wash water volume, respectively, a value of 62 mg N/L (38% of 140 mg N/L plus 52%of 17 mg N/L) from the septic effluent will be used to calculate nitrate-nitrogen loading for this project(See Kaplan-Septic Systems Handbook,Pg. 147). B. CALCULATED NITRATE-NITROGEN LOADING ' NLS§ The calculated nitrate-nitrogen impact to the soil and ultimately to the groundwater is di tcult termine due to the large number of variables involved and variables unknown at this time. These include: 1.) Impact from upgradient nitrate sources, 2.) Variability in wastewater flows, nitrogen concentrations and dilution effects from stormwater recharge, 3.) Changes in groundwater directional flow and elevation, 4.)Denitrification potential within the soil environment and within the confined and/or unconfined aquifers. The Hantzsche/Finnemore Formula is used in this report to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water from the proposed on-site septic system serving the restroom facilities. As calculated below,the property has been assessed on a total areal loading basis correlated with the total projected yearly wastewater low volumes calculated above. These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge water. This concentration cannot exceed 10 ppm nitrate-nitrogen (45 ppm as nitrate). 6