J000154-001-R-Rev0_ASS Investigation Report · RAP15/0034

J000154-001-R-Rev0                                                                         November 2015


6.2         Subsurface Conditions
The boreholes encountered a sequence of inferred alluvial soils comprising:

 Firm Sand (FILL) yellow and pale yellow to depths of approximately 1.5 m to 2.0 m bgl, over
 Sand (Natural) grey and pale grey, with some silt and organics to depths of 3.5 m bgl (maximum depth
      of investigation).

6.3         Groundwater
Groundwater was initially encountered in all boreholes during the investigation at depths of between 1.5 m
and 2.0 m bgl. The groundwater level was recorded at 2.3 m bgl during groundwater monitoring on 5
November 2015. It should be noted that drilling operations were undertaken during a “dropping tide” with
groundwater monitoring of GW1 undertaken at / around low tide. It is anticipated that the extent of
groundwater seepage encountered during earthworks and construction will be dependent upon the prevailing
weather conditions at that time and tidal conditions. However, the groundwater level is expected to rise
closer to the ground surface.

6.4         Groundwater Quality Analysis
A groundwater sample was collected from GW1 on 5 November 2015 to provide a ‘snapshot’ of the
groundwater conditions. The results of groundwater analysis are summarised in Table 1.
Table 1: Results of Groundwater Analysis

 Parameter                                       GW1

 Field Results

 Groundwater level (m bgl)                        2.3

 Field pH                                         6.2

 Electrical Conductivity (uS/cm)                  437

 Temperature (°C)                                 22.6

 Salinity (ppt)                                   0.15
                                                organic
 Observations
                                                 odour
 Laboratory Results (5 November 2015)

 Hydroxide Alkalinity as CaCO3 (mg/L)             <10

 Carbonate Alkalinity as CaCO3 (mg/L)             <10

 Bicarbonate Alkalinity as CaCO3 (mg/L)            75

 Total Alkalinity as CaCO3 (mg/L)                  75

 Acidity as CaCO3 (mg/L)                           19

 Sulfate as S (mg/L)                               <5

 Chloride (mg/L)                                  160




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