Appendix Cs. Additional Soils Information

Transcription

1 Appendix Cs Additional Soils Information

2 Managing Director: ROD MASTERS M Sc, Dip App Sci. (Agric) Dip Geo General Manager: ANDREW HUTTON B Nat Res, M.Bus Env Man. Senior Project Managers: CRAIG BAGNALL B E (Env) (Hons) CHAD STOCKHAM B E (Env) (Hons) NICOLE ARMIT B.E (Env) (Hons), M.Env.Law REF NO: MEM Friday 8 th April 2011 Melanie Bourke Environmental Officer McCollum Environmental Level Edward St Brisbane QLD 4000 Dear Melanie, RE: Codrilla EIS Responses to Soil, Overburden and Landuse Survey Report GSS Environmental understands the Codrilla EIS has been reviewed by the Queensland Department Environment and Resource Management (DERM). The issues raised by DERM in association with the Soils, Overburden and Landuse Survey Report have been forwarded to GSS Environmental for review and response. GSS Environmental provides responses to these issues, as detailed below: Issue 1: Section Soils DERM Query: A total of 28 soil profiles were investigated within the project area. This represents a mapping scale of 1 site per 179 ha. Ideally, soil surveys of mining areas should be conducted at a minimum intensity of 1 site per 100ha (as per Technical guidelines of environmental management of exploration and mining Queensland). Soil surveys of mining project areas should be conducted at a minimum scale of 1:100,000. GSSE Response: The soil survey conducted for the Codrilla site consisted of Level I, III and IV observation types (as recommended in Guidelines for Surveying Soil and Land Resources (National Committee on Soils and Terrain, 2008).) and as described in Table 1 below. Approximately 120 observations were made during the survey, 28 of those observations were full profile descriptions (Level I), which were also all sampled and laboratory tested to obtain sufficient analytical data to determine soil characteristics. GSSE understands the location of sites used for Level I observations (detailed profile descriptions) is required to be displayed and shown on soil figures as presented in the Codrilla Coal Mine Project Soil, Overburden and Land Use Survey Report, however no such requirement applies to the Level IV minor observations made during the free survey which consisted of exposed cuttings, exposure of topsoil to cm using a spade and hand auger, vegetation associations and rock outcrops. Therefore GSSE has omitted these observation sites from the soil map in the interest of professional map presentation and minor value the location of these sites would provide to the reader.

3 Page 2 Table 1 Soil Observation Types 1 Level bservation Type Types of Observations I II III Detailed Profile Description Deep Borings Laboratory Soil Assessment Soil pit excavation with soil profile described in accordance with the Australian Soil Survey Handbook. Deep borings examine material below the normal depth of the soil description and are important where subsolum and substrate properties influence land use. This is particularly so where irrigated land uses are proposed. For this survey, no irrigated land was proposed, meaning that soil description beyond the normal depth, via deep borings, was not necessary. For this survey, samples were taken from each soil layer (layers as identified from observation type I) and sent to the laboratory for many level C and D type analyses as specified in Table 17.9 of the Guidelines for Surveying Soil and Land Resources (National Committee on Soils and Terrain, 2008) IV Minor Field Observations Minor field observations are brief observations to confirm mapping boundaries, soil-type distributions or other characteristics being mapped in the survey. These are always brief, and generally constitute the majority of field observations in soil surveys due to the efficiency in gathering good quality field data to supplement and refine detailed information collected using Type I observations. For this survey, mapping observations included exposed cuttings, exposure of topsoil to 20 cm using a spade, vegetation associations and rock outcrops. 1 Adapted from Table 14.2 of the Guidelines for Surveying Soil and Land Resources (National Committee on Soils and Terrain, 2008). GSSE calculates that 120 observations across the project area of 5,010ha equates to 1 observation per 41 ha which satisfies a mapping scale of between 1:50,000 and 1:100,000. This scale satisfies the DERM requirement of 1:100,000 as stated on the recommendation above.

4 Page 3 Issue 2: Section Soils DERM Query: Section 4.1.4, Soils, states a total of 5 soil types were identified within the project area. The estimated rooting depth (ERD) used to calculate plant available water capacity (PAWC) seems to conflict with data provided within some soil profile descriptions. The Brown Duplex soil profile descriptions states that roots were evident within soil layer 2 ( m). However, an ERD of 0.18m was used to calculate PAWC. If rooting depth is deeper than the 0.18m used, then the PAWC would be higher, thus allowing a higher land suitability rating to be assigned to the soil unit. Likewise, the Yellow Duplex soil profile description states that roots are evident within layer 2 ( m). It is unlikely that roots would be impaired by electrical conductivity, exchangeable sodium percentage or unsuitable structure in a loamy sand horizon requiring the ERD to be reduced to 0.36m. Recalculate PAWC using deeper rooting depths as per soil profile descriptions or provide further evidence why shallow ERD s would be appropriate. GSSE Response: 1 Calculation of PAWC and ERD Plant Available Water Capacity (PAWC) is generally defined as the difference between field capacity and permanent wilting point. PAWC is calculated for the soil profile by summing the available water capacity over the soil s effective rooting depth (ERD). GSSE estimated ERD through use of soil chemical/physical parameters (Table 2) as well as observed rooting depth from detailed soil profile descriptions. Each of the soil unit s ERD s under discussion, i.e. Brown Duplex and Yellow Duplex, are detailed in Table 3. GSSE calculated PAWC using the PAWCER software program (a QLD approved software program) for each soil unit. Each of the soil unit s PAWC s under discussion, i.e. Brown Duplex and Yellow Duplex, are detailed in Table 3. Table 2 Effective Rooting Depth Criteria 1 Limitation # Descriptor ERD occurs where: 1 EC EC 1:5 for sorghum and wheat 1 (90% yield reduction threshold) OR >0.8 ds/m 2 Cl 1:5 >1,000 ppm 3 ESP >20% where clay content is >25% 4 ph <5.5 5 Depth to C horizons -- 6 Unsuitable subsoil structure moderate or strong columnar structure sandy free draining horizons significant rock content 1 Sorghum and wheat identified as the most likely cropping regime if cropping is applicable (Baker, 2005). Source: Burgess, 2003

5 Page 4 Soil Type Site ERD PAWC Table 3 Effective Rooting Depth Criteria Soil layers calculated Name # cm mm Layer # # 1 Comment Brown Duplex , ,2 1, , MC ,2 3 MC ,2 3 MC ,2 3 MC Average Yellow Duplex MC ,2 ERD Limitation Clay content >20% and ESP =23 in layer 3. Clay content >20% and ESP =26 in layer Massive subsoil with no root penetration (clay content 50%) & high Emerson aggregate test results of 2(3) in layer Clay content >20% and ESP =29 in layer 3 & EC at layer 3 = 0.95 ds/m. Clay content >20% and ESP =34 in layer Heavy massive clay and no observed root presence Clay content >20% and ESP =40 in layer Clay content >20% and ESP =45 in layer Clay content >20% and ESP =19 combined with very high EAT result of Class in layer 3. Clay content >20% and ESP =16 combined with very high EAT result, Class 2(3) in layer 3. Very High EAT Class 2(3) result in layer 3. Clay content >20% and ESP =13.5 combined with very high EAT result, Class 2(3) in layer Very High EAT Class 2(3) result in layer 3. MC ,2 No observed root presence in layer 3. MC ,2 3 MC ,2 Average Refers to limitations as described in Table 2 2 Amended based on review of data; layer 1 excluded 3 Amended based on review of data; layer 2 included 4 Amended based on review of data; layer 2 included to 40cm. Clay content >20% and ESP =22 in layer Although clay content >20% and ESP =22 in layer 2; roots expected to 0.4m.

6 Page 5 1 Interpretation of PAWC and Land Suitability The Brown Duplex soil has an average PAWC of 33 mm (standard error 8). This is a severe moisture limitation and places this soil type, in accordance with the Burgess guideline in Table 4, in Land suitability Class 4 for Beef Cattle Grazing. This class of land is subsequently classed as Agricultural Land Class C3 land as it is marginal agricultural land requiring major inputs required to sustain a grazing use. The Yellow Duplex soil has an average PAWC of 47 mm (standard error 5.6). This is a severe moisture limitation and places this soil type, in accordance with the Burgess guideline in Table 4, in Land suitability Class 3 for Beef Cattle Grazing. This class of land is subsequently classed as Agricultural Land Class C2 land as it is moderate quality grazing land and/or moderately suitable for pasture improvement. Table 4 PAWC values and Land Suitability Classes Guideline Source Land suitability Ranking for Rainfed Cropping DME (1995) > 150 mm mm mm mm < 75mm Burgess 2010 guidelines in prep. > 150mm mm mm mm < 70mm Land suitability Ranking for Beef Cattle Grazing DME (1995) > 125mm PAWC mm mm 50-75mm < 50mm Burgess 2010 guidelines in prep. Source: Table Reproduced from pers comm. B. Forster Conclusion > 90mm PAWC 70-90mm 35-70mm < 35mm - The review of the PAWC values for the Codrilla project site has confirmed that the land covered by the Brown Duplex soil has Land Suitability Class 4 and Agricultural Land Classes of C3. It has brought about an amendment for the land covered by the Yellow Duplex soil with Land Suitability increasing from 4 to 3, and Agricultural Land Classes increasing from C3 to C

7 Page 6 Issue 3: Good Quality Agricultural Land DERM Query: The mapping of existing GQAL in the Isaac Regional Council Planning Scheme indicates that the project area contains two areas of Class C1 land that is considered to be GQAL. Findings in the EIS indicate that land within the project area is not Class C1. However, justification has not been provided of the variation with the IRC Planning Scheme. The EIS should comment on and justify any variation from GQAL mapping shown in the IRC Planning Scheme. GSSE Response: GSSE obtained the Broadsound Shire Planning Scheme Map 5 Rural Preferred Use Area, from the Isaac Regional Council. This map indicated areas of Good Quality Agricultural Land for the region. The Codrilla project area has no GQAL mapped on this figure and therefore GSSE believes no further comment or justification in the EIS is required. The above mentioned Map 5 is attached with the Codrilla Project boundary indicated. Regards, GSS Environmental Clayton Richards Senior Project Consultant