Land Capability Assessment ... The Land Capability Assessment involved a desktop assessment, field investigation

  • View
    0

  • Download
    0

Embed Size (px)

Text of Land Capability Assessment ... The Land Capability Assessment involved a desktop assessment, field...

  • Appendix H Land Capability Assessment

    H

    Land Capability A

    ssessm ent

  • 1.

    w w w . e c o z . c o m . a u

    Land Capability

    Assessment:

    Noonamah Ridge Estate

    Prepared for: Intrapac Projects Pty Ltd

    Prepared by: EcOz Environmental Consultants

    2015

  • Client: Intrapac Projects Pty Ltd ii

    Doc Title: Land Capability Assessment: Noonamah Ridge Estate

    This page has been intentionally left blank

  • Client: Intrapac Projects Pty Ltd iii

    Doc Title: Land Capability Assessment: Noonamah Ridge Estate

    Document Control Record

    Document Code: EZ14403A-C0301-DA-R-0003

    Catalogue Number: 55472

    Project Manager: Glen Ewers

    Author(s): Helen Dwyer, Justine Shailes

    Approved by: Glen Ewers

    Approval date: 17 August 2015

    DOCUMENT HISTORY

    Version Issue Date Brief Description Reviewer/Approver

    1.A 28 Apr 2015 Report preparation by authors -

    1.B 6 May 2015 Internal review Glen Ewers

    1.C 11 May 2015 Internal review David van den Hoek

    1.D-F 12 May 2015 Update of report post review Helen Dwyer

    1.0 14 May 2015 Draft shared internally for comments -

    1.1-4 10 Jun 2015 Updated report incorporating comments received Max Shifman, Paul Nicholls & Martin Klopper

    1.5 17 Aug 2015 Report complete and ready for inclusion in EIS -

    Recipients are responsible for eliminating all superseded documents in their possession.

    EcOz Pty Ltd.

    ABN: 81 143 989 039

    Winlow House, 3rd Floor

    75 Woods Street

    DARWIN NT 0800

    GPO Box 381, Darwin NT 0800

    Telephone: +61 8 8981 1100

    Facsimile: +61 8 8981 1102

    Email: ecoz@ecoz.com.au

    Internet: www.ecoz.com.au

    RELIANCE, USES and LIMITATIONS

    This report is copyright and is to be used only for its intended purpose by the intended recipient, and is not to be copied or used in any

    other way. The report may be relied upon for its intended purpose within the limits of the following disclaimer.

    This study, report and analyses have been based on the information available to EcOz Environmental Consultants at the time of

    preparation. EcOz Environmental Consultants accepts responsibility for the report and its conclusions to the extent that the information

    was sufficient and accurate at the time of preparation. EcOz Environmental Consultants does not take responsibility for errors and

    omissions due to incorrect information or information not available to EcOz Environmental Consultants at the time of preparation of the

    study, report or analyses.

    mailto:ecoz@ecoz.com.au http://www.ecoz.com.au/

  • Client: Intrapac Projects Pty Ltd iv

    Doc Title: Land Capability Assessment: Noonamah Ridge Estate

    This page has been intentionally left blank

  • Client: Intrapac Projects Pty Ltd v

    Doc Title: Land Capability Assessment: Noonamah Ridge Estate

    Executive Summary

    This report investigates potential locations for on-site wastewater treatment and disposal systems within the

    proposed Noonamah Ridge Estate, located on Section 5827, 507, 5758 and 5761 Hundred of Strangways.

    The Land Capability Assessment involved a desktop assessment, field investigation and laboratory analysis

    of soil samples from soil test pits, and targeted common and relatively unconstrained land units (i.e. no test

    pits were excavated in rocky ridge areas or creek lines). Ten soil test pits were excavated in the north-

    western portion of Sections 5827 and 5758 for the purpose of describing and assessing soil types and

    characteristics relevant to on-site wastewater management in accordance with in the Guidelines for Land

    Capability Assessment for On-site Wastewater Management (DoH 2014). Key features including depth, rock

    and gravel content, soil texture, structure and colour, and presence of water table were recorded, while

    laboratory samples were analysed for key physical and chemical parameters.

    Intrapac currently plans to provide a variety of lot sizes and associated infrastructure, and the majority of lots

    will be sewered and connected to centralised, communal wastewater treatment systems capable of treating

    large volumes of wastewater. Additional to this, there is potential for a number of larger lots to be developed

    with individual on-site wastewater management systems. The early stages of development will likely involve

    a release of these larger lots in the north-western section of the proposed development. Therefore, the focus

    of this LCA was a targeted assessment of the north-western section of the proposed development (which

    may include the site of one of the communal wastewater treatment systems), and then an extrapolation of

    the results of this assessment into an investigation and identification of the land units within the entire site

    that are potentially capable of supporting large-scale systems. As this development will be staged over a

    number of decades, accurate locations for rural lots and sites for centralised systems were not available at

    the time of reporting. Siting and design of on-site wastewater management systems outside of the

    investigation area will require more detailed, site-specific investigations at each location.

    The LCA covered ten test pits over six land units – 1c, 2b1, 2b2, 3c, 6a2 and 6b. The site characteristics

    and soil test pits identified that:

     The site covers a wide range of landforms and land units and necessitated extrapolation of soil test

    pit data across the represented land units.

     The overall landform and drainage of the project area includes steep, rocky ridge lines in the centre

    of the project area with slopes of up to 15 % and rapid drainage. Side slopes and undulating

    uplands surround these, before the site flattens into lower slopes and eventually drainage floors

    and creek lines. The slopes range from 2-5 % in the side slopes and undulating uplands to 0-2 %

    in the lower slopes and drainage floors. Drainage is poor in the drainage floors and creek lines,

    and there are a number of seasonally inundated areas. Drainage from the project area is

    predominantly west into a tributary of the Elizabeth River, with some drainage toward the Adelaide

    River to the east.

     There are sufficient unconstrained soils within the sampled land units capable of supporting on-site

    wastewater management systems, subject to site-specific designs once locations are finalised.

     Soil data indicates that the most appropriate (i.e. unconstrained) of the surveyed land units for

    siting of wastewater management systems are 1c, 2b1, 2b2 and 3c.

     Test pits within land units 6a2 and 6b indicate low capability due to shallow, sandy soils with high

    permeability and high seasonal water tables. Some areas of these land units are seasonally-

    inundated and on-site wastewater management systems should not be sited within these land

    units.

     Test pits within land units 1c, 2b1, 2b2 and 3c indicate gravelly, sandy clay loam to sandy loam

    with some occurrences of silty clay loam. Although gravels and coarse fragments were common

    the areas surrounding the test pits had no rock outcrop. The soils were well-drained, with no

  • Client: Intrapac Projects Pty Ltd vi

    Doc Title: Land Capability Assessment: Noonamah Ridge Estate

    presence of water tables, although some test pits within land unit 1c and 3c had mottling in the

    lower profiles (approximately 0.8 m below ground level) indicating potential water ingress.

     Laboratory results for soil pH, EC, P-sorption capacity, sodicity and Emerson aggregate classes

    indicate high-moderate capability for all analytes, and none of the tested parameters are likely to

    pose limitations to on-site wastewater treatment and disposal.

     Test pits were located on the lower slope landforms within the respective land units. It should be

    noted that the upper slopes and ridge lines within land unit 1c are very rocky and steep. Locations

    of wastewater management systems within land unit 1c should be closely assessed to ensure there

    is sufficient soil and slope to accommodate the proposed system.

     Specific wastewater treatment and land application systems were not assessed as it is understood

    Intrapac plan to install specialised treatment systems capable of treating to tertiary quality, which

    would allow for any land application system. The sizing and design of these systems will be

    undertaken by the installer, who will also maintain the system.

    The above conclusions are based on the findings of the investigated sites and are assumed to be

    representative of the greater property; however, lot-specific limitations may occur. Additionally, not all land

    units within the project area were assessed in this LCA, and there may be additional land units that are

    capable (or not) of supporting proposed on-site wastewater management systems. Each lot, or specific

    location for centralised wastewater systems, will