081128 - Lots 5 - 8 Soil Tests · OPW18/0155

                                 LOTS 5 TO 8, SETTLERS COVE, SERENITY CLOSE, NOOSA



5.5       Pavements
The design of pavements (flexible and rigid) is based upon the CBR value of the subgrade material. The
subgrade CBR may be obtained by i) laboratory soaked CBR tests, ii) correlations with DCP tests, and iii) the
Queensland Transport Pavement Design Manual – 1990 which provides presumptive insitu CBR values
based on soil type and site conditions.
At this site, the subgrade material is expected to be natural loose to medium dense silty sand/sand and/or
future fill. Section 5.3.3, Table 5.5 of the Queensland Transport Pavement Design Manual, suggests the
CBR values in Table 4 for various subgrade soil types and site conditions.
Table 3: Presumptive CBR Values
Subgrade Type          Drainage conditions         Presumptive CBR (%)
Silty Sand/Sand            Poor                    7
                           Good                    10


For this site, we recommend that a preliminary design CBR of 10% be adopted for pavement design within
the anticipated subgrade. The subgrade CBR must be confirmed by DCP testing following earthworks
and/or excavation to subgrade level.

5.6       Drainage
Drainage should be designed to direct water away from building walls and footings. Waters collected from
hard surface (eg. terraces and paved areas) should be directed to the Council stormwater system along the
road frontage. Subsurface disposal of stormwater via RIPs with outlets at least 2 m below the ground
surface is not recommended within 5 m of the crest of the slopes in the western part of the site as shown on
Figure No. 1. The stormwater collection and disposal system should be designed by a hydraulic engineer.



6.0      IMPORTANT INFORMATION
Your attention is drawn to the document - “Important Information About Your Geotechnical Engineering
Report”, which is included in Appendix B of this report.




December 2008
Report No. 087682058 002 Rev.1                         6