THE HILLS SHIRE COUNCIL
2.3 R EGIONAL H YDROGEOLOGY
4.1.2 C ASTLE H ILL
The site stratigraphy, as observed in the boreholes drilled at Castle Hill cemetery typically comprised natural (i.e. undisturbed) silty clay soil over weathered shale / siltstone and/or fine grained sandstone bedrock. The shallowest bedrock was encountered at BH-CH12 (0.9m bgs) while the depth to bedrock exceeded 2.0m at BH- CH02, BH-CH09, BH-CH-10 and BH-CH13. The bedrock was initially estimated to be extremely low to very low in strength, becoming stronger (~low to medium strength)
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
G16080CEM-R01F Page 9 of 12
Table 4: Subsurface Conditions – Castle Hill Cemetery
Layer /
Unit Description Depth to Base of
Layer (m)
NATURAL SOIL
Silty CLAY: orange-brown and red-brown, becoming pale grey with depth, medium to high plasticity, with minor ironstone gravel content.
0.9 to >2.0
BEDROCK SHALE / SILTSTONE/SANDSTONE: weathered --
No groundwater or water seepage was observed during the drilling of the boreholes, or during the short time (less than 10 minutes) that they remained open.
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
5 D
ISCUSSIONGEE has been advised by the Hills Shire Council that a single burial plot should be 4 feet deep (~1.2m), while a double burial plot should be 6 feet deep (~1.8m).
At Sackville North, the majority of the boreholes encountered bedrock at less than 1.2m depth. The only exceptions were BH-SN01 and SN-SN10 where the depths to bedrock was 1.4m and 1.2m bgs respectively. Considering that nearby boreholes were shallower, the deeper soil profiles at these two locations appear to be isolated occurrences. In this regard, it is unlikely that this site will be suitable for widespread burial. The only possibility is if the excavator or backhoe used to excavate the burial plots has the capacity to penetrating into the upper portion of the sandstone bedrock formation, which is typically estimated to be extremely low to very low in strength.
Should this be possible, then locations such as BH-SN04, BH-SN05, BH-SN09, BH-SN11, BH-SN12, BH-SN13, BH-SN14, BH-SN15 and BH-SN16, along with BH-SN01 and SN- SN10, may be suitable for single burial plots. Ideally, this should confirmed with the equipment proposed to dig the burial plots.
At Castle Hill, the majority of the boreholes encountered bedrock at depths exceeding 1.2m. The only exceptions were BH-CH01, BH-CH11 and BH-CN12 with BH-CH01 located near the entrance to the cemetery and BH-CH11 and BH-CH12 located in the north-eastern portion of the site near the existing carpark. Boreholes where the depth of soil was equal to, or exceeded 1.8m included BH-CH02, BH-CH09, BH-CH10, BH- CH13 and BH-CH15. Considering that nearby boreholes were shallower, the deeper soil profiles at these locations appear to be isolated occurrences. Like with Sackville North, should the equipment used to excavate the burial plots be capable of penetrating the upper portion of the bedrock formation, which is typically estimated to be extremely low to very low in strength, then locations such as BH-CH04, BH-CH08 and BH-CH19 may also be suitable for double burial plots. As previously mentioned, this should confirmed with the equipment proposed to dig the burial plots.
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
G16080CEM-R01F Page 11 of 12
6 G
ENERALL
IMITATIONSSoil and rock formations are variable. The logs or other information presented as part of this report indicate the approximate subsurface conditions only at the specific test locations. Boundaries between zones on the logs or stratigraphic sections are often not distinct, but rather are transitional and have been interpreted.
The precision with which subsurface conditions are indicated depends largely on the frequency and method of sampling, and on the uniformity of subsurface conditions.
The spacing of test sites also usually reflects budget and schedule constraints.
Groundwater conditions described in this report refer only to those observed at the place and under circumstances noted in the report. The conditions may vary seasonally or as a consequence of construction activities on the site or adjacent sites.
Where ground conditions encountered at the site differ significantly from those anticipated in the report, either due to natural variability of subsurface conditions or construction activities, it is a condition of this report that GEE be notified of any variations and be provided with an opportunity to review the recommendations of this report. Recognition of changed soil and rock conditions requires experience and it is recommended that a suitably experienced geotechnical engineer be engaged to visit the site with sufficient frequency to detect if conditions have changed significantly.
The comments given in this report are intended only for the guidance of the design engineer, or for other purposes specifically noted in the report. The number of boreholes or test excavations necessary to determine all relevant underground conditions which may affect construction costs, techniques and equipment choice, scheduling, and sequence of operations would normally be greater than has been carried out for design purposes. Contractors should therefore rely on their own additional investigations, as well as their own interpretations of the borehole data in this report, as to how subsurface conditions may affect their work.
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
If you have any questions about the content of this letter, please do not hesitate to contact the undersigned.
Yours sincerely
Stephen McCormack Principal
R
EFERENCES1. Department of Mineral Resources, 1966: Sydney 1:250,000Geological Series Map Sheet SI/56-05 (Edition 3).
2. Department of Mineral Resources, 1983: Sydney 1:100,000Geological Series Map Sheet 9130 (Edition 1).
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
F
IGURESORDINARY MEETING OF COUNCIL 28 FEBRUARY 2017
SITE PLANSackville Cemetery437 Sackville Ferry Road, Sackville North Aerial Image Source: provided by Nearmap Ltd (www.nearmap.com) - image dated 20/01/2016
82 BRIDGE STREETLANE COVE NSW 2066P - 61 (2) 9420 3361E - info@geoenvironmental.com.auwww.geoenvironmental.com.au DRAWN: DATE:SCALE:
JOB No.: N.T.S A. Chiem TITLE:14 Jun 2
G16080C
Nort h
Approximate Approximate Extent of Native Vegetation Conse
SN01 SN02 SN03 SN04 SN05 SN07 SN06
SN08
SN09
SN10
SN11
SN12 SN16
SN15
SN13SN14
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SITE PLANCastle Hill Cemetery - Gilbert Road Castle Hill NSW Aerial Image Source: provided by Nearmap Ltd (www.nearmap.com) - image dated 6/12/2015
A 2 82 BRIDGE STREETLANE COVE NSW 2066P - 61 (2) 9420 3361E - info@geoenvironmental.com.auwww.geoenvironmental.com.au DRAWN: DATE:SCALE:
JOB No.:REVISION: N.T.S A. Chiem TITLE:FIGURE No.:14 Jun 2016
G16080CEM
Nort h
CH10
CH06
CH05 CH01 CH08 CH11
CH16
CH07CH09CH17
CH18CH19 CH14
CH13CH12
CH02
CH03 CH04 CH15
3m Buffer to Native VegatationConservation Areas
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Geotechnical Investigation Report Sackville North and Castle Hill Cemeteries
A
PPENDIXA
Site Plans (2 Sheets)
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