64 Pheasant Lane, Doonan septic design

3.3 Soil Classification



                                                   Soil Classification - Adopted
        Borehole Nos                                                                                1&2
        Soil Category Adopted                                                                         2
        Indicative Drainage                                                                     Well Drained
        Structure                                                                                  Weakly
        Texture                                                                                 Clayey Sand
        Indicative Permeability P (m/d) as Ksat*                                                     >3.0
        Recommended DLR (AS/NZS 1547 / 2012)                                                          50




     4.0 Recommendations:
     4.1 Treatment Facility:
     The on-site treatment facility to service the new dwelling is to be an Advanced Enviro-Septic System (AES). This
     system has a Chief Executive Approval # 14/2014 for Advanced Secondary Effluent. The Person Equivalent (PE) for
     this system is to be no less than 6.

     A new min 4450lt septic tank is to be installed to service the new dwelling and must comply with AS/NZS:1546.

     All wastewater from the new dwelling is to be directed to the new septic tank then to the AES bed.

     The Land Application Area is to be an Advanced Enviro-Septic Infiltration Bed of 29.6m2.




      5.0 Design Calculation
      The serviceable life of the Land Application Area will be compromised if the design flow is exceeded. Any
      proposed changes to the position of the Land Application Area, System Type or House Design will require a
      reassessment of this site. For our calculations we have assessed the design flow as follows:

                                                    Design Calculation
         DLR (mm/d) (secondary quality effluent)                                                     50
         Hydraulic load (lt/day/person) Tank Water / 4 bedrooms                                      120
         Design Flow Q (lt/day)   PE: 6                                                              720
         Design sizing calculation                                                           L = Q /(DLRxW)
                                                                                                = (720 / 50)
         Disposal area A+B (square metres) AS/NZS1547:2012 + downhill loading                       26.6m2
         Nominated Configuration (metres) AES System Design Calculations               = 12.6 x 2.35m (L xW) 29.6m2
         A new 4450L Septic Tank is required.                                                AES System EP 6




                                                                                  C Copyright Lance Picton 2020 design & content. 3/12