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III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS Wastewater Flow Volume Projections NLS§3.4,3.5,3.6. To determine nitrate-nitrogen loading from any project,wastewater flow volumes must be determined as accurately as possible. Domestic flow volume projections have been approximated from the USEPA Onsite Wastewater Treatme stems Manual, Pg. 3-4. Residential (domestic) flow volumes average approximate 69 gallons/person/day. The EHD specifies that each bedroom has the potential for two people,therefore ea- r-bedroom has an ADF 140 gpd,, dpy. The existing house on Parcel 1 has four bedrooms/three bathrooms and the existing se on - proposed Parcel 3 has three bedrooms/two baths. Wastewater Characteristics Blackwater will originate from toilets and graywater from showers, laundry,teeth brushing, dishwashing and hand washing. Additional wastewater constituents may consist of other liquids to the system, such as coffee,juices, etc. The scientific literature cites nitrogen concentrations in domestic septic effluent typically ranging from 17 mg N/L for basins, sinks, etc. to 140 mg N/L fo ilet`.v�ass. Therefore,taking a composite of these values, a nitrogen concentration of�j mg N/L_within the septic effluent will be used to calculate nitrate-nitrogen loading for this project(See Kaplan-Septic Systems Handbook, Pg. 147). CALCULATED NITRATE-NITROGEN LOADING NLS§3.3,3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil and potentially to the groundwater is difficult to determine due to the large number of variables involved and variables unknown at this time. These include: 1.) Impact from upgradient agricultural sources, 2.) Variability in wastewater flows, nitrogen concentrations and dilution effects from stormwater recharge, 3.) Changes in groundwater directional flow and elevation, and 4.) Denitrification potential within the clay soil environment and within the confined and/or unconfined aquifers. The Hantzsche/Finnem_ore Formula is used below to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water. The first nitrate loading-ca"-latior.,bbelow will be for a complete project with two new residential structures,both wi If three b o baths on proposed Parcels 2 and 4, along with the existing seven bedrooms on proposed Parcels Land 3. Therefore,the total wastewater flow volume based upon the parameters expressed above ' : 13 edrooms x 140 gals/bedroom/day= 1,820 gals/day. The second series of nitrate loading calculations will factor in second unit dwellings for each individual Parcel. The property has been assessed on a total areal loading basis after the Minor Subdivision and Lot Line Adjustment creating a final smaller Parcel size of 9.41 acres from the original 13.09 acres. This is correlated with the total projected yearly wastewater flow volume calculated above. Page -7- Chesney Consulting