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ONSITE WASTEWATER TREATMENT SYSTEM DESIGN: OPERATIONAL COMTONENTS AND PARAMETERS TO MITIGATE NITRATE LOADING The following is an overview describing the operational design: The OWTS design begins with a 2,000 gallon P&L Concrete, Inc. standard precast septic tank that is set with the inlet invert elevation 13 inches below existing grade(top of tank at grade). Potential surge flow is easily accommodated with this tank size given that the modular home is a small, three bedroom structure (§7.1.2). The tank is to be situated in line with the influent tightline. In the second compartment of the septic tank, an Orenco Universal BioTube Pump Vault is to be installed. Within the screened pump vault is a duplex pump system. The pumps will alternate operations and will be set to time dosing through the Orenco MVP Duplex Panel. Top float= High Level Alarm,with lag pump enabled. No. 2 float over-ride timer on. Bottom float=Timer on and off. Timer starts with off time count down. Off time is 60 min; on time is 38 seconds. Over-ride timer off time is 30 min and on time is 38 seconds. Screened effluent is pressurized through a 1.0" transport line; then through a 1" to 4" PVC reducer; then into a 4" tightline manifold as illustrated on the design plans. As the effluent expands from 1" to 4"delivery, the energy of the pumped effluent decreases and allows the effluent to rise within the manifold with enough speed and volume for the effluent to seek its own level throughout the length of the manifold. Effluent then flows relatively equally into each of the three 22' elbows,then into the perforated piping. For this locale,the SJC OWTS Standards require 240 lineal ft of leachline (LFLL), and 960 sf of infiltrative surface area. Three, 80 ft long (240 LFLL)perforated piping will "T" connect to the 22°elbow from the manifold, as illustrated. The three 4" dia. perforated laterals are to be lasered- in level and capped at the ends. The 100%reserve area is also illustrated adjacent to the west of the three leachlines. The floor of the 3 leachline trenches shall be set at 24" below final grade. This will maintain the required 8' separation distance (due to natural rapid permeability mitigation) between the soil- effluent interface and the highest anticipated depth to groundwater: 12" drain rock under laterals+ 4" drain rock for ht. of perforated piping+2" drain rock above laterals+ 6" native excavated soil cover over each leachline trench(§9.4)=24". 120" (10 ft)=highest anticipated depth to groundwater minus 24" = 96" (8.0' separation distance). Filter fabric is to be laid over the drain rock before 6" native soil cover backfill to surrounding grade. The Attachments to this Report include the following Technical Data Sheets(T.D.S.) in Appendix D: 1. MVP-DAX DM Setting Instructions for time dosing. 2. Splice Box 3. Float Switch Assemblies T.D.S. 4. PF Series 4" Submersible Effluent Duplex Pump System T.D.S. 5. High Head H=V(W/Check Valve) 6. Universal Biotube Pump Vault T.D.S. Page-3- Chesney Consulting