smiths lake planning study volume 1: text - Great Lakes Council

SOILS AND GEOTECHNICAL 4
2 SOILS AND GEOTECHNICAL
2.1 Introduction
The objective of the soils and geotechnical component of the study is to describe the physical
characteristics of the Smiths Lake Area and Smiths Lake Village Area and assess urban and
land capability and formulate development guidelines. This component of the study and the
preparation of this report has been undertaken by Robert Carr & Associates Pty Ltd and:
• Outlines the geology, physical properties and distribution of soil and rocks within the study
area with particular emphasis on acid sulphate soils.
• Assesses land and urban capability in terms of slope instability, high erosion potential,
foundation conditions and acid sulphate soils.
• Provides geotechnical management guidelines for urban and low low-scale development.
The area of the study has been classified into two areas, the Smiths Lake Area (SLA) and the
Smiths Lake Village Area (SLVA). The SLA and the SLVA contain a variety of landforms and
vegetation, including steep headlands and slopes to low-lying coastal and estuarine lands. The
SLVA comprises an urbanised area of about 3 km 2 . The SLA includes 60km 2 , of which 38km 2
comprises the shallow saline coastal lagoon, Smiths Lake with the remainder comprising forest,
rural development and the small urban villages of Tarbuck Bay and Charlotte Bay.
2.2 Methodology
Investigation methodology has involved review of available background data, field mapping,
drilling and sampling and laboratory testing of soil and groundwater samples.
2.2.1 Background Data
Background data relevant to the study area has been sourced from:
• Webb, McKeown and Associates, 1998, Smiths Lake Estuary Process study.
• Department of Land and Water Conservation (DLWC). Soil profiles from 11 locations
throughout the study area have been sourced through the Soil Data System and are
appended. Acid Sulphate Soil Risk Maps (Wooton, Pacific Palms, Myall Lake and Seal
Rocks sheets at a scale of 1: 25,000) have been used in the acid sulphate soil assessment.
• Department of Public Works & Services (DPWS), geotechnical investigations carried out
between 1991 and 1996 for the Pacific Palms and Smiths Lake waste water and water
supply infrastructure. Investigations included subsurface investigation with physical and
chemical testing of soil and water samples.
• Geological and groundwater data as outlined in the Geology of the Camberwell, Dungog
and Buladelah 1:100,000 Sheet.
SMITHS_LAKE_PLANNING_STUDY.DOC
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