Laserfiche WebLink
'22� <br /> Climatic Data: Rainfall versus Evapotranspiration <br /> NLS§3.2. It is generally and scientifically accepted that when precipitation exceeds <br /> evapotranspiration(Eto), deep percolation of surface rainwater may occur. Evapotranspiration <br /> refers to water evaporation that takes place both at the soil surface and transpiration by plants. <br /> Since the leachfield is to be constructed at-grade, evapotranspiration will be a significant factor. <br /> The CIMIS Data for Station 248 in Zone 14 indicates an evapotranspiration yearly total of 57 <br /> inches. The average yearly rainfall is 10 inches. Consequently,there is a significant probability <br /> that effluent will evaporate from the three leachlines during most months of the year. <br /> III. NITRATE LOADING STUDY FINDINGS <br /> A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS <br /> Wastewater Flow Volume Projections <br /> Wastewater flow volumes from the project are anticipated to be very low, possibly as low as 5-10 <br /> gpd. Given that Water Use Computation Tables assign 150 gals/fixture for stores, and the facility will <br /> have two unisex restrooms (one for customer use; one for owner's personal use),this number will be <br /> used in the calculations and discussions below and provides a significant safety factor. The yearly <br /> wastewater flow volume is as follows and is based on the facility only operating on weekends, federal <br /> and Islamic holidays, from 8:OOAM to 5:OOPM: <br /> 150 gpd ADF x 2 d/wk x 52 wks/yr= 15,600 g/yr. + 10 federal holidays x 150 gpd= 1,500 gals+3 <br /> Islamic holidays x 150 gpd=450. Total= 17,550 gallons. This figure will be used in the nitrate <br /> loading calculations below. <br /> I <br /> Wastewater Characteristics <br /> The domestic wastewater generated from the facility will be composed of blackwater from <br /> toilets/urinals and greywater from hand washing. There will be no high organic loading from any <br /> additions to the septic system such as offal and blood. Additional wastewater constituents may <br /> consist of other liquids to the system such as low strength cleaning liquids, etc. No industrial or <br /> commercial chemicals, solvents, etc. should ever be introduced into the wastewater treatment <br /> system. It is imperative that low strength and low volumes of cleaners are used in the restrooms <br /> since they can disrupt the septic tank biology. <br /> The scientific literature cites nitrogen concentrations in domestic septic effluent ranging from 17 mg <br /> N/L for basins, sinks, etc. to 140 mg N/L for toilet wastes. A value of 62 mg N/L is typically used <br /> for domestic calculations, as indicated in the literature (See Kaplan-Septic Systems Handbook,Pg. 147). <br /> Page -5- <br /> Chesney Consulting <br />