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This chart illustrates that evapotranspiration far exceeds precipitation,even when using higher rainfall data that exceeds normal rainfall data by 56%. Only in the months of January,February,November and December would deep percolation potentially occur. This data illustrates a relatively high potential for there to be significant evapotranspiration(or bare soil surface evaporation) from a wastewater disposal system design that may take advantage of evapotranspiration during favorable months of the year. III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS Wastewater Flow Volume Projections To determine nitrate-nitrogen loading from the project,wastewater flow volumes will be conservatively determined. Typically,loading projections are based on the maximum or total number of employees and customers who may potentially use the toilet/sink,etc. on a workday basis. Several variables are involved in estimating wastewater flows from a facility. Wastewater flow volume projections for facilities in unsewered areas have been historically and typically calculated under numerous guidelines and scenarios, as illustrated in the following list: 1. Published Data in the San Joaquin County EHD Sewage Standards and scientific literature. 2. Number of bathroom fixtures correlated with bathroom use per capita for a facility. 3. Number of parking spaces at a facility. 4. Maximum number of people(e.g.,employees,customers,etc.). 5. Historical wastewater flow data from an existing facility. Since it cannot be adequately determined how many people will use the new modular building restrooms on a daily basis,an estimate of assigning three flushes per hour,per toilet,per day is logical,reasonable, contemporary, and applicable. Archaic Standards of 150 Average Daily Flow(ADF)per toilet are based on old-style toilets with a five gallon flush. New toilets use 1.5 gallons per flush. Although numbers of on-site people have not been estimated in the Application,the ADF for sizing criteria must be based on the premise of using low-flow toilets at 1.5 gallons/flush. Anticipated flow volumes are as follows: A total of 24 flushes/day will be assigned for the men's toilet and 24 flushes/day for the women's toilet(24 flushes/toilet/day=3 flushes/hr/8 hr day)for a total of 48 flushes/day x 1.5 gals/flush=72 gals+ 0.25 gallons for hand washing x 48 bathroom trips= 84 gallons ADF from the new modular building. A filter bed disposal structure is recommended in lieu of conventional leachlines to reduce the disposal area footprint. However,conventional leachlines may be installed if economically feasible. The primary criterion is that the floor of the filter bed or leachline trench cannot be any deeper than 24 inches below existing grade due to the water table at 6.75 ft below grade. Wastewater Flow Characteristics It is assumed there will be no cooking,or food production in the modular building. Therefore,there should be no concentrated organic loading. The characteristics of the wastewater flow will be predominately blackwater from toilets,with a comparatively small volume of graywater from sinks,or other sources of graywater. Additional wastewater constituents may consist of coffee,juices or other similar type liquids to the system. No industrial or commercial chemicals,solvents,etc. are to be introduced into the septic system. From the anticipated wastewater characteristics described above,the nitrogen emanating from the project may be at a higher concentration than what would normally be found in a typical domestic or household system. 6