Free Range Broiler Farm, Arapohue: Groundwater assessment

Transcription

1 Free Range Broiler Farm, Arapohue: Groundwater assessment Prepared for Date Job Number

2 Document Control Title: Date Version Description Prepared by: Reviewed by: 28/08/ Updates following planner tech review 30/08/ Updates following hydrogeological technical review TIR ASCO JMS TIR CRSS JMS Authorised by: Distribution: Northland Regional Council Kaipara District Council (FILE) 1 copy 1 copy 1 copy 1 copy

3 Table of contents 1 Introduction 1 2 Site description Development proposal Groundwater and borehole requirement Report structure 3 3 Background Site investigation Site survey of existing groundwater bores Pumping tests and water quality testing 8 4 Site water requirements Poultry drinking water Washdown water Heating water make-up Staff drinking and cleaning Cooling system Dairy stock 10 5 Environmental setting Site description Climate Wairoa River Existing groundwater bores Existing groundwater take consents 12 6 Hydrogeology Site geology/ hydrogeology Alluvial Deposits Northland Allochthon Intrusive Andesite Awhitu Group Sandstone: Summary hydrogeological parameters Groundwater recharge Groundwater levels and flow directions Water quality Groundwater availability Groundwater availability and allocation Potential well yield assessment Groundwater supply conclusions 17 7 Technical assessment of effects Groundwater drawdown and stream depletion assessment Saline intrusion assessment Groundwater contamination assessment Settlement effects Effect on groundwater availability 19 8 Assessment criteria table for groundwater take consent 20 9 Conclusions Applicability 23

4 Appendix A : Appendix B : Appendix C : Appendix D : Figures Site works reports Pumping test analysis and outputs Conceptual hydrogeological mode

5 1 1 Introduction (Tegel) has entered into a sale and purchase agreement for a site at 5763 State Highway 12 (SH12), Arapohue, Dargaville, ( the site ). Tegel is proposing to develop a free range broiler chicken farm on the site. Tegel is seeking resource consent to abstract groundwater at a rate of up to 350 m 3 /day, with an annual maximum groundwater take of 63,250 m 3 /year. The abstracted groundwater is intended to be used for the purpose of poultry and dairy farming support. (T+T) have been engaged to conduct a groundwater assessment of the site to support the resource consent application. Tegel is proposing to install up to three production bores located within areas of andesite found on the site. Each bore would be designed to pump up to 160 m 3 /day. It is expected that up to five investigation/production bores will need to be installed to confirm the three sites for production purposes. To reduce the volumes of groundwater required to supply the proposed poultry farm development, Tegel is proposing to construct a rainwater harvesting, collection and treatment system to supply the majority of the poultry farm water supply. Details of the rainwater harvesting system is set out in the Civil Preliminary Design Report attached in Volume 2 to the Assessment of Effects on the Environment (AEE) Report. The evaluation provided in this document confirms that the proposed groundwater take, in combination with others in the catchment, will not exceed the assessed groundwater availability or affect other nearby users based on the results of our site investigations and a review of regional council data.

6 2 2 Site description (Tegel) proposes to develop a free range broiler chicken farm at 5763 State Highway 12 (SH12), Arapohue, Dargaville, ( the site ) (refer Figure 2.1 below). The site is approximately 12 km south of the Dargaville township (Refer Figure 1, Appendix A) and is bounded by the following: State Highway 12 to the west; Farm land to the north and east; and, Whakahara Road to the south. The site is currently operated as a dairy farm. The existing farm buildings on site include a 50 bale rotary milking shed, calf rearing sheds, an implement shed and five dwellings. The existing farm buildings will be retained onsite. Figure 2.1: Site boundary Source: Northland Regional Council Local Maps, 2017 The topography at the site can be divided into the flat area to the west, and the hilly area to the east. The western area of the site comprises an alluvial flat flood plain. This area ranges in elevation from 1.5 to 2.0 mrl and is located within the Kaipara District Plan (KDP) flood susceptibility area, as well as being identified as Northland flood susceptible land in the Regional Water and Soil Plan for Northland (RWSP). The eastern portion of the site is generally more elevated and of a higher relief, with ground surfaces ranging from 2.0 mrl to 70 mrl at the back of the site. A limestone quarry is located in the north-eastern corner of the site and has an approximate footprint of 3500 m² and is around 5 m in depth. The material being quarried is a sheared, chalky limestone and is the same material which is gravelling the farm races.

7 3 There are four main existing farm drains on site, that run perpendicular to SH12 from the hill catchment and ultimately to the Wairoa River. The drains are typically 2 m wide and approximately 0.8 m deep. They run alongside the metalled races, which are raised approximately 0.25 m above the surrounding paddocks. The existing site water supply is provided by a combination of site dams and water supply bores. The known water supply bores are shown on Figure 2, Appendix A. The water supply bores with pumps installed and used on site currently are referred to as EB 1, which is located on higher ground to the northeast of the main dairy shed and EB 2, which is located on the eastern edge of the alluvial floodplain adjacent to the road from the site quarry. 2.1 Development proposal The construction of the proposed poultry farm will include the development of 32 free range poultry sheds that will be clustered into four groups of eight. Single shed dimensions will be approximately 138 m long x 20 m wide x 4.5 m in height. The sheds are proposed to be located on the flat, western portion of the site. Developing the proposed farm will require earthworks, the construction of the foundations and sheds, installation of infrastructure, including an energy centre building powered by litter combustion, stormwater management devices, wastewater treatment and disposal, rainwater storage tanks, installation of groundwater bores, water reticulation and a water treatment plant. In addition, the proposed poultry farm development will require construction of associated facilities, such as workers accommodation, utility sheds and vehicle tracks around the sheds connecting to a new access off SH12. A planted bund is proposed to be constructed around the sheds to mitigate against flooding and provide visual screening. The farm would be stocked with up to approximately 1.32 million chickens at a time. 2.2 Groundwater and borehole requirement Tegel is seeking resource consent to abstract groundwater at a rate of up to 350 m 3 /day, with an annual maximum groundwater take of 63,250 m 3 /year. The abstracted groundwater is intended to be used for the purpose of poultry and dairy farming support. The abstracted groundwater will be stored in holding tanks on site. Tegel is proposing to install up to three new production bores on site to supply the majority of groundwater demands and may either decommission or upgrade the existing bores. The details of the existing bores are discussed in section below. The groundwater take and effects assessment covers these requirements:- Maximum daily rate 300 m 3 /day for poultry support + 50 m 3 /day for dairy support; and Maximum daily take of 350 m 3 /day Maximum annual rate Up to 45,000 m 3 /year (the observed range is 14,000 m 3 /year to almost 45,000 m 3 /year with an average of 26,000 m 3 /year) for poultry support and 18,250 m 3 /year for dairy support; and For total maximum annual take of 63,250 m 3 /year Installation of up to five exploration/production boreholes to provide the proposed water supply (refer Appendix A, Figure 3 for locations). 2.3 Report structure This report is structured as follows:-

8 4 Background details for this reporting including details of: Groundwater site investigation; and Pumping tests at bore EB 1 and water quality testing. Site water requirements; Environmental setting; Site hydrogeology description; and Technical assessment of effects.

9 5 3 Background Groundwater is currently abstracted from two of three existing groundwater bores which are shown on Figure 2 attached in Appendix A. These are shown as bores EB 1, EB 2, and EB 3. Figure 2 also shows four bores indicated on the site sales details (Bores A through D). None of these bores are indicated on the NRC database nor were they located during our site investigation, and are reported to be not currently used 1. Therefore, they have not been assessed as part of this assessment. We understand that the three existing bores were drilled historically by a local driller, however there is no clear indication of their age. At ground surface the bores typically consist of 100 mm diameter PVC riser pipe and currently do not have bore head security measures installed (concrete pad, animal exclusion or secure headworks). We understand that the two bores in use (EB 1 and EB 2) are used for dairy shed wash down and stock watering. 3.1 Site investigation The site hydrogeological investigation was undertaken in July 2017 by drilling and pumping test contractors and (T+T) technical staff and comprised the following phases:- Visual site survey to locate and measure existing site boreholes; Installation of monitoring wells and monitoring piezometers as part of site geotechnical investigation; Step testing and constant rate testing of site production borehole (EB 1); Groundwater sample collection at EB 1 and laboratory analysis of the samples; and Water level dipping and field parameter measurement of groundwater samples Site survey of existing groundwater bores T+T engaged Drill Force Ltd (Drill Force) on behalf of Tegel to undertake visual assessments of the existing bores on site and interview the current site manager to collect any knowledge he may hold relating to the bores (see Appendix B for the survey information). Drill Force visited the site on 13 July 2017 and were accompanied by the site manager to each of the three existing bores on site. The three site bores are referred to as existing bores 1, 2, and 3 (i.e. EB 1, EB 2, and EB 3). Drill Force later returned to the site to undertake pumping tests on EB 1 between 17 and 21 July, Based on discussions with the farm manager, we understand that the majority of groundwater abstracted from the site is from EB 1 (estimated at approximately 25 m³/day), for use as wash-water in the dairy shed. EB 1 is approximately 40 m deep (below existing ground level) and located approximately 250 m east of the main dairy shed. The bore was observed to be an open 100 mm PVC pipe with alkathene pump riser pipe protruding from the ground (see Figure 3.1 below). The bore did not have bore head security measures installed (concrete pad, animal exclusion, backflow prevention, secure headworks). We have inferred (based on geological mapping) that the bore abstracts water from an intrusion of andesite rock. EB 1 was selected for pumping test investigations and water quality sampling, reported below. A second bore (EB 2) is located approximately 400m northeast of the main dairy shed, inferred to be screened within alluvial material. EB 2 is approximately 11 m deep. The farm manager indicated that 1 dated 09 August 2017, 12:40 pm, from Cameron Goodhue (Ray White, Whangarei) to Charlotte MacDonald (T+T), confirming purple dots represent bores not currently used by the farm system.

10 6 the bore was relatively low yielding (up to 7 m³/day) and suffers from a decline in yield if excessively pumped. The third bore (EB 3) is located approximately 900 m south-southeast from the main dairy shed. EB 3 is inferred to be within an intrusion of andesite rock based on nearby geotechnical investigations. EB 3 is approximately 50 m deep, but did not have a pump installed at time of the inspection. The farm manager had little information about any historical abstraction from the bore. Similarly to EB 1, EB 3 was observed to be simply an open 100 mm PVC pipe protruding from the ground. The bore did not have some bore head security measures installed. Figure 3.1: Photograph of EB 1.

11 7 Table 3.1: Summary of information gathered by Drill Force Bore reference Location in relation to the main dairy shed Inferred geological unit Estimated depth (below ground) Measured water level (bgl) Estimated available drawdown Current abstraction/ use EB m east Andesite rock 40 m 18.5 m 9 m Approximately 25 m³/day EB m northeast Alluvial sand 11 m EB m southsoutheast 1 m 9 m Approximately 7 m³/day Andesite rock 49 m Not currently used no pump installed Notes 100 mm PVC casing with no bore head protection or animal exclusion. Farm manager stated that he undertakes 6-monthly treatment of the pump for iron build-up 100 mm PVC casing located within corrugated iron pump shed. Farm manager stated that if abstraction exceeds 7 m³/day the bore heaves and yield significantly declines 100 mm PVC casing with no bore head protection or animal exclusion.

12 Pumping tests and water quality testing Pumping tests of an on-site bore (EB 1) inferred to be abstracting groundwater from an andesite intrusion were undertaken in July The purpose of the pumping tests and subsequent analysis was to estimate the hydraulic properties of the andesite aquifer. The results of the factual report (refer Appendix C) formed the basis of this technical assessment of effects relating to a proposal to abstract groundwater from the andesite aquifer on site. The following pumping tests were undertaken: Step testing, comprising four steps of 60 minute duration, following by a 12 hr recovery period; Constant rate pumping test for three days at a pumping rate of 242 m³/day; Measured recovery for a three day period following pumping; and Collection and analysis of groundwater samples for standard drinking water determinands. Pumping tests indicate the following with respect to the hydraulic properties of the andesite aquifer on site: Early time drawdown and residual drawdown information from the constant rate test indicate that the andesite aquifer is unconfined or semi-confined and has a transmissivity of approximately 175 m²/day and assumed storativity of approximately 0.05; Late time drawdown data within EB 1 and water level data from observation bores inferred to be screened within alluvial material adjacent to the andesite rock indicate that a no-flow boundary is likely to exist at the boundary of the andesite rock. Furthermore, residual drawdown data appears to be consistent with the relatively slow recovery of groundwater levels that would be expected if a no-flow boundary exists; Groundwater samples collected from EB 1 during the pumping tests indicate that the groundwater quality is generally within drinking water guideline values, except for slight exceedances of iron above aesthetic guidelines. Electrical conductivity (EC) field tests at boreholes across the site testing indicates elevated EC (over 1000 μs/cm) on the floodplain and lower EC (around 500 μs/cm) in the hill country adjacent to the floodplain. The assessed hydraulic gradient at the eastern edge of the floodplain is 3.33 x 10-3 based on levels measured during the site investigation. The detailed results of pumping tests are provided in in Appendix C.

13 9 4 Site water requirements To operate the proposed free range poultry farm and the 150 herd dairy farm, the volume of water required is outlined below. Drinking water for poultry 243 m³/day; Shed washdown water required for cleaning of the sheds; 7.2 m³/day Make-up for the hot water heating system required to heat the sheds; 0 m³/day Staff drinking and cleaning water; 1.3 m³/day Shed cooling system (mist); and 25 m³/day Treatment losses 14 to 28 m³/day Dairy stock drinking water and cleaning of milking shed 50 m³/day. The total daily demand is assessed as 300 m 3 for the poultry operation and 50 m 3 for the dairy operation. Tegel has an extensive network of poultry farms across New Zealand and thus has access to a significant dataset of measured water consumption data. On the basis of this information and equipment specifications (where available), Tegel has built a water consumption model to represent the specific farm configuration proposed for the subject site. The model ensures that consent is sought for abstraction of an appropriate volume of water, based on efficient use. The majority of this demand will be supplied from rainwater harvesting, which significantly reduces the groundwater abstraction volumes. Further, it is worth noting, that the capital cost to install the rainwater harvesting infrastructure in comparison to the cost of groundwater supply infrastructure is significantly higher. Tegel has pursued the rainwater harvesting option as it aligns with the company s sustainability goals to incorporate sustainable building design and engineering into the proposed poultry farm development. As the rainwater harvesting system is based on rainfall collection, which is highly variable, there is a risk that during extreme dry periods there may be insufficient supply available from rainfall. The consequences of this for chicken health would be critical. Therefore, the bore water system must have sufficient capacity to meet the average total demand of 350 m 3 /day. The volumes of water applied for is based on the water use model provided by Tegel. Additional rationale for the volumes of water required for the farm is set out in the following sections Poultry drinking water Each shed operates on a 56 day cycle, with chickens growing for 42 days, with sheds being empty for 14 days between cycles. The cycles will be staggered between the poultry sheds. Tegel has provided an analysis of the water demands for the sheds, and the graphical output for this is included in Appendix A as Chart 1. This analysis shows a combined demand varying between approximately 150 and 327 m 3 /day, with an average of 243 m 3 /day. The poultry drinking water demand is based on actual consumption rates from Tegel s extensive network of poultry farms across New Zealand and is consistent with published information. All of the Tegel broiler farms consist of the internationally recognised Ross 308 broiler bird 2. The poultry water demand is calculated using the following key assumptions: Mass (kg) of birds on the proposed farm on any given day; 2 Ross 308 Broiler, Aviagen Group, Ross 308 Broiler Performance Objectives report 2014 (growth rate and feed conversion).

14 10 Expected feed demand of the birds which is based on a combination of the size and sex of birds on the farm and the nutritional content 3 of the birds feed supply; and Expected water: feed ratio 4 of the birds which is based on the bird genetics, nutritional content of the birds feed supply, and the drinking systems installed in the poultry sheds Washdown water The volume of washdown water required to clean a shed is 10 m 3 /shed. There will be approximately five shed wash-downs per week. This is an average of 7.2 m 3 /day to be considered for long term supply requirements. The volume of washdown water required is based on water use on Tegel existing farms on a shed area basis Heating water make-up The hot water system proposed to be installed in each shed for heating is a closed system. Therefore, no make-up water is required. Tegel advises that this will be a closed system and that any make-up water is expected to be minor. No specific allowance has been made for this demand, on the assumption that it falls within the contingencies allowed for elsewhere Staff drinking and cleaning The proposed poultry farm will employ approximately 32 staff. Typical water consumption data set out in reference documents 5 suggest an allowance of 40 L/person/day for site staff during a working day and based on standard water fixtures. The water demand for staff on this basis would be 1.3 m 3 /day. Tegel is proposing to construct four dwellings. It is intended that the proposed houses will be selfsufficient for water supply, with their demands met from individual roof tanks Cooling system The 25 m³/day water demand for the mist cooling system is based on the mist cooling systems design specifications, frequency of unusually warm climatic conditions and volumes from existing Tegel farms Dairy stock The 50 m³/day dairy stock demand is based on approximately 15 m³/day for stock drinking purposes and a 35 m³/day for shed washdown. 3 Ross 308 Broiler, Aviagen Group, Ross 308 Broiler Nutrition Specifications report Ross 308 Broiler, Aviagen Group, Ross 308 Broiler Management Handbook 2014 (Water: feed rations) 5 Auckland Regional Council, Technical Publication No.58, On-site wastewater Systems: Design and Management Manual Third Edition ARC Technical Publication 2004, prepared by A W Ormiston (ARC Consultant) & R E Floyd.

15 11 5 Environmental setting 5.1 Site description The site is located in a rural region of Northland approximately 12 km south of the Dargaville township and approximately 500 m east of the Northern Wairoa River. The site is bounded by: State Highway 12 to the west; Farm land to the north and east; and, Whakahara Road to the south. The western portion of the site is generally flat and ranges in elevation from 1.5 to 2.0 m RL, while the eastern section of the site is of higher relief and ranges in elevation from 2 to 70 m RL. The site is predominantly covered in grass with the presence of farm drains and a watercourse that flows westward to the Wairoa River. 5.2 Climate A climate study of the Northland Region conducted by NIWA 6 indicates that the annual rainfall normal for the area is 1137 mm/year. This assessment is based on data collected between 1981 and 2010 at Dargaville. 5.3 Wairoa River The Wairoa River (often referred to as the Northern Wairoa River) rises in the Tangihua Range and flows west towards Dargaville before turning south east and discharging to the Kaipara Harbour. The Northland Regional Council (NRC) indicates that the Wairoa River has a mean annual low flow (MALF) of 12 m 3 /sec 7. The allocation limit for the Wairoa River is reported by NRC as 50 % of the MALF and therefore up to 6 m 3 /sec may be allocated. The Wairoa River level is affected by tides in the Kaipara Harbour to upstream of Dargaville. The tidal affect is clearly seen up stream of the site at Dargaville with a measurable stage height fluctuation of around 3 to 3.5 m through each tidal cycle. 5.4 Existing groundwater bores The NRC database was searched for borehole records. Seventeen boreholes were located in the two surface water catchments which form part of Wairoa/West Coast area. The site straddles the two surface water catchments. No boreholes were reported within the boundary of the site. The closest borehole record on the NRC database is LOC , located approximately 200 m north from the site boundary. LOC is reported as being only 9.7 m deep and installed pre-plan. Recorded bore depths ranged from 8.2 to 53 m depth, while static water levels were reported from m (presumed to be artesian) to 40.6 m (assumed to be a dip to water). While none of these bores are reported to have pumping test information available, the bore logs indicate that reported well yields are in the range 21.9 to 197 m 3 /day. The majority of logs indicate that the bores are completed in rock or limestone. Only two bores indicate that shingle layers were encountered. 6 Chappell, P.R The climate and weather of Northland. NIWA Science and Technology Series 59, 40 pp., ISSN Northland Regional Council (2017). GIS viewer: Indicative Surface Water Allocation by Catchment 8 August Accessed 25 August, 2017.

16 Existing groundwater take consents There are no groundwater take consents listed in the NRC consents database in the two surface water catchments assessed as part of the groundwater availability assessment. We have assumed that the closest bore (LOC ) is pumped in accordance with permitted activity criteria.

17 13 6 Hydrogeology 6.1 Site geology/ hydrogeology The site falls within the Main Northland Aquifer: Kaipara Flats management area. Published geological mapping of the site 8 shows that four main geological units are present on the site. Each of these have been described below in terms of structural and hydrogeological properties Alluvial Deposits A large portion of the site, consisting the low relief land adjacent and inland of SH12 is underlain by alluvial deposits associated with alluvial flood plains of Wairoa River (refer Figure 1, Appendix A). The alluvial deposits are indicated to consist of unconsolidated to poorly consolidated mud, sand, gravel and peat deposits. Groundwater within the alluvial material is expected to exist as a relatively shallow, unconfined aquifer. Measured groundwater levels during winter within the plains area were measured at between approximately 0.2 m and 0.8 m below ground surface, consistent with a shallow unconfined aquifer. The alluvial deposits are indicated to be capable of yielding low quantities of groundwater. The existing bore (EB 2) situated in the alluvial deposits indicated to be relatively low yielding (up to 7 m³/day) and is reported to yield declining volumes if excessively pumped. It is also assumed, that due to its low topography, that the alluvial deposits may be hydraulically connected to the Wairoa River and have elevated salinity concentrations. Recharge of this aquifer is believed to occur as a result of a combination of rainfall and recharge from the Wairoa River Northland Allochthon To the east of the alluvial flood plain and inland of the Wairoa River, geological mapping indicates that the site is generally underlain by the Northern Allochthon, comprising a matrix of Mangakahia Complex mudstones, with included tectonic blocks of Motatau Complex limestone and Tangihua Complex basaltic pillow lava and sheet flows. The Northern Allochthon is expected to extend westwards, underlying the Wairoa alluvial flood plain at depth. The Northern Allochthon is generally a low permeability geological unit and generally accepted to yield and transmit low quantities of groundwater Intrusive Andesite Geological mapping indicates that two localised intrusions of basalt or andesite rock are present on the site, both located to the east of the main dairy shed. Visual observations and geotechnical investigations suggested that there may be at least two further intrusions (refer Figure 2, Appendix A). The extent of these is not currently well defined and has been inferred. The andesite is expected to have intruded up through the Northern Allochthon (i.e. is younger) and is therefore likely to be laterally bounded by the lower permeability Allochthon material. To the west, where the andesite abuts the alluvial flood plain, there may be some hydraulic connection between the rock and the alluvial deposits. The permeability of volcanic rock such as andesite is typically controlled by the degree of fracturing or weathering of the rock. We expect that groundwater yields from the andesite rock are likely to be comparatively higher than the other three geological units mapped on the site. 8 Edbrooke, S.W.; Brook, F.J. (compilers) 2009: Geology of the Whangarei area. Institute of Geological & Nuclear Sciences 1: geological map 2. 1 sheet + 68 p. Lower Hutt, New Zealand. GNS Science.

18 14 EB 1, situated within the andesite, shows that water levels within the western-most andesite intrusion were approximately 18.5 m below ground level. This equates to a water level that is approximately 1.8 mrl. The intrusive andesite was tested during the pumping of EB 1. The testing indicates that the andesite in which EB 1 is constructed is not hydraulically connected to the alluvial deposits. The groundwater within the andesite is likely to occur as a result of interconnectivity of fractures within the rock mass. The results of the testing suggest that recharge of groundwater within the fractures may be limited and slow recovering when over pumped. However, it should be noted that while the andesite in which EB 1 is screened, did not show signs of a hydraulic connection with the alluvial deposits, other andesite intrusions within the area may, and is dependent on the interconnectivity of the fractures within the host andesite. As the andesite is at a higher topography to the alluvial deposits and Wairoa River, recharge is likely to be predominantly through rainfall Awhitu Group Sandstone: An area of Awhitu Group sandstone consisting cemented, dune-bedded sand is also mapped within the south-eastern portion of the site. The nature and extent of the sandstone is not currently well defined. Pumping tests within this unit have been undertaken in other regions which identify the Awhitu Group sandstone as a potential groundwater source rock. The Awhitu Group Sandstone is known in other regions as being able to yield significant quantities of groundwater. The Awhitu Group Sandstone may be hydraulically connected to other aquifers nearby including the alluvial deposits and nearby andesite intrusions. As the Awhitu Group Sandstone is at a higher topography to the alluvial deposits and Wairoa River, recharge of the sandstone is likely to be predominantly through rainfall. Attached in Appendix D is a conceptual hydrogeological model of the site.

19 Summary hydrogeological parameters A summary of the hydrogeological parameters used for our assessment is provided within Table 6.1 below. Table 6.1: Summary of hydrogeological parameters Geological unit Aquifer thickness (m) Permeability (m/day) Transmissivity (m 2 /day) Storativity or Specific yield Alluvial deposits (Sands) x (unconfined) 1 x 10-4 (confined) Alluvial deposits (Silts/clays)1 13+ < 8.64 x 10-5 <0.5 N/A Northland Allochthon N/A N/A N/A Intrusive Andesite 1, Awhitu Group Sandstone 1, : Based on assumed parameters. 2: Based on pumping tests undertaken in EB 1. 3: Based on testing undertaken on the same unit in different regions. 6.2 Groundwater recharge Groundwater recharge across the site is assessed as 10 % of annual average rainfall based on previous experience in the Ruawai area 9 and in this type of hydrogeological terrain. Factors that influenced this assessment include: Water logged soils on the alluvial flood plain indicating restricted vertical and lateral drainage; and Relatively low permeability of surface soils. 6.3 Groundwater levels and flow directions Groundwater levels were measured during the pumping tests within the pumped bore and a series of piezometers installed to monitor drawdown effects. A groundwater contour plan is attached with the reporting in Appendix C. These contours are based on measured groundwater levels prior to pumping. The groundwater measurements indicate that the water level within the andesite is approximately RL 2 m. The groundwater level measured within the alluvial deposits indicate a groundwater level of around RL 1.5 m near the base of the hills with a groundwater level of RL 1 m measured within BH1. The hydraulic gradient is assessed as 3.33 x Based on measured groundwater levels and topography across the site, we expect that groundwater flows in a west to south-west direction, towards the Wairoa River. Groundwater flows within the shallow alluvial deposits are expected to be very low due to the low permeability nature of the underlying soils and shallow hydraulic gradient toward the Wairoa River. 6.4 Water quality During the pumping tests electrical conductivities were measured in groundwater pumped from the production bore and the observation wells. From the measured electrical conductivity readings a 9 SKM, 2004, Ruawai Town Water Supply Bores Hydrogeology and Bore Security Assessment, prepared for Kaipara District Council

20 16 contour plan has been developed and is attached in Appendix C with the pumping test report. The contour plan indicates elevated electrical conductivity levels within the areas of lower lying soils (i.e. the alluvial deposits). Water quality within the alluvial deposits is expected to reflect that of the Wairoa River and is anticipated to have elevated salinity levels. This is also reflected in the measured electrical conductivity levels, which are higher than those typically measured at higher elevations (i.e. within the andesite). Groundwater samples collected from EB 1 during the pumping test (before the pumping test, after the first step test, and after three days pumping) indicate that the groundwater within the andesite rock generally meets guideline values for drinking water quality, with the exception of slightly elevated iron in exceedance of the aesthetic guideline value 10. The ph at the end of pumping was slightly less than the aesthetic guideline value. No groundwater quality sample results are available from the Awhitu Group Sandstone. A sample of groundwater from this unit would need to be analysed prior to confirming its suitability for the desired uses. 6.5 Groundwater availability Groundwater availability and allocation Based on the methodology set out in the draft National Environmental Standard 11 (NES) up to 35 % of the recharge to a catchment may be available for allocation by water take consent, i.e. this volume is the groundwater availability. The Tegel site lies across two mapped surface water catchments in area totalling km 2. Mean annual rainfall is 1137 mm and groundwater at the site is dominantly recharged by rainfall infiltration. It is noted above (section 6.2) that we have assumed that 10 % of rainfall supports groundwater recharge. On the basis of this description, groundwater recharge is assessed as 4,924 m 3 /day. After applying the limits set out in the draft NES up to 1720 m 3 /day and 629,000 m 3 /year of groundwater is available for allocation. There are no groundwater or surface water take consents recorded in these two surface water catchments based on a recent download of the NRC consents point database. Assuming that up to 500 m 3 /day must be made available for s.14 (RMA) purposes (i.e. reasonable stock watering and household drinking water purposes) and permitted activity takes means that over 1200 m 3 /day (459,000 m 3 /year) is available for allocation. On this basis there is sufficient water to allocate up to 350 m 3 /day and 63,250 m 3 /year for dairy and poultry support Potential well yield assessment A qualitative assessment based on the final drawdown after the constant rate pumping test indicates that a suitably constructed bore within the andesite rock that EB 1 abstracts from could be capable of supplying up to a maximum of between m³/day on a sustainable basis. We also consider it likely that the other intrusions of andesite rock indicated to be within the site are likely to 10 Ministry of Health (2008). Drinking-water Standards for New Zealand 2005 (Revised 2008). Wellington: Ministry of Health. 11 Ministry for the Environment, March 2008, Proposed National Environmental Standard on Ecological Flows and Water Levels, Discussion Document, (section 5.1 proposes limits) Publication number ME 868

21 17 be capable of supplying similar daily quantities of groundwater (subject to further investigation). On this basis, we would expect that the andesite rock intrusions on site could conservatively yield in excess of 300 m³/day, subject to appropriate construction of up to three suitable additional production bores Groundwater supply conclusions Based on assessments completed to date, the localised intrusions of andesite rock observed across elevated parts of the site appear to hold the most potential for a sustainable source of groundwater. We have inferred that two of the three existing bores on site are likely to be installed into this material. The existing bores on site do not have appropriate bore head security measures and the bore construction is not known. The diameter of the existing bores (100 mm) may restrict the pump size that can be installed, which would in turn restrict abstraction rates. If Tegel choses to retain the existing bores on site, bore head security measures will be retrofitted. Based the water supply ratio between rainfall harvesting and groundwater, we estimate that 3 suitably constructed bores on the site could supply up to 350 m³/day from andesite intrusions on site. We expect that up to five locations may need to be investigated to achieve three suitable production wells. Accordingly, the resource consent application has included an application for drilling boreholes at five locations across the site. The proposed locations are tabulated below (Table 6.2) and included on Figure 3. Table 6.2 Proposed investigation/production borehole locations Bore Number NZTM Easting NZTM Northing PB PB PB PB PB

22 18 7 Technical assessment of effects 7.1 Groundwater drawdown and stream depletion assessment The results of the pumping testing undertaken on EB 1 indicate no identifiable drawdown was observed within the observation piezometers during the pumping test, indicating that there is very little to no hydraulic connection between the andesite and the alluvial sediments (i.e. there is little of no flow between them). The observed water levels show an increased drawdown after three days of pumping at rates of 240 m 3 /day, further supporting this conclusion. As the andesite is considered to have very little to no hydraulic connection with the alluvial sediments, the andesite is unlikely to be connected to the more distant Wairoa River. Therefore we have assessed that the depletion effect on Wairoa River flows caused by groundwater abstraction from the andesite will be less than measurable. 7.2 Saline intrusion assessment We have used standard techniques (refer Schmorak and Mercado 12 ) to estimate the potential for saline upconing in the proposed pumping bores. Based on early time hydraulic conductivity values calculated using the pumping test data and our understanding of the bore configuration, the assessment indicates that any higher salinity groundwater in the andesite is expected to occur over 70 m below mean sea level (based on a static water level within the andesite of 1.8 mrl). The assessment shows that the maximum yield available from the borehole before the occurrence of saline upconing is 2,200 m 3 /day. As the proposed groundwater take is only 350 m 3 /day, the likelihood of saline upconing into the andesite is assessed as very small. Based on the pumping test data there was no hydraulic connection observed between groundwater in the andesite and groundwater in the fine-grained materials comprising the alluvial floodplain of the Wairoa River. For saline intrusion to occur laterally from the Wairoa River, abstraction of groundwater from the andesite would need to induce lateral groundwater flow from the alluvial flood plain, towards the bore. Because of the hydraulic boundary, we expect that this is unlikely to occur and accordingly, saline intrusion is unlikely. 7.3 Groundwater contamination assessment It is proposed that groundwater bores be installed away from any onsite wastewater or effluent disposal field with a minimum separation distance of 20 m. Suitable wellhead protection will be installed to meet NRC guidelines and to minimise the risk of surface or subsurface contamination reaching the pumping bore. 7.4 Settlement effects The static water level at the EB 1 location was reported as approximately 18 metres below ground level in July 2017 prior to the pumping test. The groundwater is assessed as being below the level of any residual soils that may be affected by declines in groundwater levels. Our evaluation, based on the conceptual hydrogeology is that the andesite is not extensive (if it exists at all) beneath the floodplain west of EB 1. This means that groundwater level changes in the andesite sequence are unlikely to affect groundwater levels in the alluvial floodplain. This inference is confirmed by pumping test observations which showed that groundwater level changes in the andesite were not observed to affect groundwater levels at all beneath the floodplain. 12 Schmorak, S., and A. Mercado, Upconing of fresh water sea water interface below pumping wells, field study, Water Resources Research, v.5, pp , 1969.

23 19 Given the expected stiffness of the andesite rock, the amount of settlement caused by pumping groundwater from the andesite intrusions is assessed as inconsequential over the alluvial floodplain and beneath the elevated areas of andesite. The current groundwater level is considered to be so far below the residual soils on the andesite that changes in the andesite groundwater level will not cause observable settlement in the residual soils on the site. Effects off-site are not expected to be observed. We also note that observation of settlement caused by pumping is likely to be obscured by the effects of shrinking and cracking of drying residual soils in the floodplain and overlying the andesite during a typical summer and rewetting in the following winter. Our evaluation is that ground settlement caused by pumping drawdowns will not impact any buildings or structures located within the vicinity of the bore. Overall, the settlement effects of the proposed groundwater abstraction are assessed as inconsequential. 7.5 Effect on groundwater availability The groundwater availability and allocation for the catchments to this site is fully described in section (above). Applying appropriate limits and guidelines confirms that up to 1720 m 3 /day and 629,000 m 3 /year of groundwater is available for allocation. After allowing for other reasonable uses over 1200 m 3 /day (459,000 m 3 /year) of groundwater is available for allocation. On this basis there is sufficient water to allocate up to 350 m 3 /day and 63,250 m 3 /year for dairy and poultry support.

24 20 8 Assessment criteria table for groundwater take consent Assessment criteria for groundwater take applications is provided under of the Regional Water and Soil Plan for Northland, and is assessed below in Table 8.1. Table 8.1 Assessment criteria for groundwater takes Assessment Criteria for Groundwater Takes a The cumulative effects of the proposed groundwater take and existing groundwater users in relation to the average annual recharge of the aquifer. b The extent to which the proposed groundwater take may adversely affect other groundwater and surface water users, and the adequacy of any pump test analysis to confirm those effects. c The proximity to the freshwater/seawater interface and the likelihood of any seawater intrusion affecting groundwater users. Response The Tegel site lies in two mapped surface water catchments, an area totalling km 2. Mean annual rainfall is 1137 mm at Dargaville. Groundwater at the site is dominantly recharged by rainfall infiltration. Groundwater recharge is assessed as 10 % of rainfall. Groundwater recharge is assessed as 4,924 m 3 /day. After applying the interim limits set out in the Draft National Environmental Standard for Water Levels and Ecological Flows up to 1720 m 3 /day and 629,000 m 3 /year of groundwater is available for allocation. There are no groundwater or surface water take consents recorded in these two surface water catchments. Allowing for up to 500 m 3 /day for s.14 RMA purposes means that over 1200 m 3 /day (459,000 m 3 /year) of groundwater is available for allocation. On this basis there is sufficient water to allocate up to 350 m 3 /day and 63,250 m 3 /year for dairy and poultry support. A pumping test was undertaken at EB 1, which is drilled in an andesite intrusion and currently provides a water supply to the site milking shed. A step test and constant rate test were completed at EB 1. The constant rate test was undertaken at 240 m 3 /day (approximately 2.8 L/s) pumping for three days. Pumping test observations suggest that andesite has a transmissivity of approximately 175 m 2 /day with corresponding hydraulic conductivity of 17.5 m/day. Based on the pumping test of EB 1 showed that drawdown effects were confined to the andesite. On that basis off-site effects i.e. beyond the andesite are considered unlikely to be measurable. Up to three further production bores are proposed to be drilled within areas of andesite found on the site. Each bore would be designed to pump up to 160 m 3 /day. It is expected that up to five investigation bores will be need to be installed to confirm the three sites needed for production purposes. The pumping test is assessed as adequate to use for estimating the effect of pumping production bores at a combined rate of up to 350 m 3 /day. The Tegel site is adjacent to the Wairoa River which discharges to the northern end of the Kaipara Harbour and is tidally affected where it is monitored at Dargaville. Saline intrusion could occur from the river (i.e. laterally) and/or upconing from depth at a pumping bore (i.e. vertically). Based on early time hydraulic conductivity values calculated using the pumping test data and our understanding of the bore configuration, the assessment indicates that any higher salinity groundwater in the andesite is expected occur over 70 m below mean sea level (based on a static water level within the andesite of 1.8 mrl). The assessment shows that the maximum yield available

25 21 from the borehole before the occurrence of saline upconing is 2,200 m 3 /day. As the proposed groundwater take is only 350 m 3 /day, the likelihood of saline upconing into the andesite is assessed as very small. d The proximity of the bore and the standing groundwater level to any effluent disposal field and the likelihood of contaminants being drawn into the aquifer as a result of pumping. Based on the pumping test data there was no hydraulic connection observed between groundwater in the andesite and groundwater in the fine-grained materials comprising the alluvial floodplain of the Wairoa River. For saline intrusion to occur laterally from the Wairoa River, abstraction of groundwater from the andesite would need to induce lateral groundwater flow from the alluvial flood plain, towards the bore. Because of the hydraulic boundary, we expect that is unlikely to occur and accordingly, saline intrusion is unlikely. Any future effluent disposal fields and site water supply bores are proposed to be installed at least 20 m apart.

26 22 9 Conclusions Tegel propose to install up to three further production bores located within areas of andesite found on the site in order to abstract groundwater at a rate of up to 350 m 3 /day. Each bore would be designed to pump up to 160 m 3 /day of groundwater. It is expected that up to five investigation/production bores will need to be installed to confirm the three sites needed for production purposes. The evaluation provided in this report concludes that:- The proposed groundwater take, in combination with others in the catchment, will not exceed the assessed groundwater availability; There are no nearby groundwater users that may be affected based on our site investigations and review of regional council data; Our assessment is that saline upconing or saline intrusion is unlikely to occur in the proposed production bores; and The production bores are proposed to be installed at least 20 m away from effluent disposal fields.

27 23 10 Applicability This report has been prepared for the exclusive use of our client, with respect to our letter of engagement dated 2 August 2017 and it may not be relied upon in other contexts or for any other purpose, or by any person other than our client, without our prior written agreement. Report prepared by: Authorised for by: Tony Reynolds Senior Hydrogeologist Jenny Simpson Project Director Technical review completed by:... Chris Shanks Hydrogeologist \\ttgroup.local\files\aklprojects\ \workingmaterial\planning\volume 2 - tech reports (pd review)\technical report c - groundwater assessment\dargaville tegel groundwater assessment report (pd review) smar.docx

28 Appendix A : Figures Location plan including surface water catchments Site plans (including nearby wells, and proposed bores) Modelled poultry drinking water demand

29 The Site LEGEND Catchment Catchment No Area km² km² L:\ \WorkingMaterial\CAD\FIG\ GW-F1.dwg F1 29/08/ :09:29 PM ORIGINAL IN COLOUR 105 Carlton Gore Road, Newmarket, Auckland

30 L:\ \WorkingMaterial\CAD\FIG\ GW-F2.dwg, F2, 25/08/2017 3:07:52 PM, rbs ORIGINAL IN COLOUR 105 Carlton Gore Road, Newmarket, Auckland

31 L:\ \WorkingMaterial\CAD\FIG\ GW-F3.dwg, F3, 25/08/2017 4:11:40 PM, rbs ORIGINAL IN COLOUR 105 Carlton Gore Road, Newmarket, Auckland

32 Estimated water use (m³/day) 350 Chart 1: Modeled Total poultry Water drinking Use (Cubm) water demand Time (Days)

33 Appendix B : Site works reports Driller walkover report

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