1.0 INTRODUCTION. 28 th November Hawke s Bay Project Management Limited 1139 Maraekakaho Road RD5 Hastings, 4175.

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1 28 th November 2016 Hawke s Bay Project Management Limited 1139 Maraekakaho Road RD5 Hastings, 4175 Attn: John Roil RE: IRONGATE INDUSTRIAL AREA WATER SUPPLY 1.0 INTRODUCTION Industrial development is proposed for the Irongate area that extends between Maraekakaho Road and the expressway, Figure 1. Water supply is required for the development that includes the provision of a consumptive supply for workers within the development area and a firefighting supply. The following volumes were supplied (MWH, 2009) for consideration: Consumptive Use: 0.5L/s/ha (58L/s peak demand and 115Ha); Average use 24L/s (2,070m 3 /d) based on a peaking factor of 2; Fire Fighting: 100L/s (agreed design fire flow); and Peak demand including firefighting 135L/s (based on 60% of 58L/s and 100L/s fire fighting). FIGURE 1: IRONGATE SITE LOCATION PLAN Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 1

2 The taking of water for the purpose of firefighting under Regional Resource Management Plan (RRMP) Section 14 (3) (e) this use does not require a resource consent. However, there is a requirement for a bore permit and the well could not be used for any other purpose unless it too was within the limits of the permitted activity rule (53). The taking of water for consumptive purposes has an identified requirement with a peak demand of 58L/s (5,011m 3 /d) and average rate of 24L/s (2,070m 3 /d). This volume exceeds the RRMP permitted take of 20m 3 /d, as such a resource consent will be required. When assessing new groundwater abstractions it is important to consider the ability of the proposed abstraction source/s to supply at the required rate and volume. This is particularly important given the high instantaneous rate of 100L/s required for the firefighting purpose. To improve understanding of the aquifer capabilities a conceptual hydrogeological model is developed for the area and a comparative analysis is made with other abstractions. In addition, for water permit consent applications HBRC must consider the potential for the proposed abstraction to adversely impact on the surrounding area, this is known as an Assessment of Environmental Effects (AEE). Specifically, the AEE for a groundwater abstraction will have reference to the potential effects on nearby surface water, interference with other existing well users and the overall aquifer sustainability. 2.0 CONCEPTUAL HYDROGEOLOGICAL MODEL The property is to the west of the main Heretaunga Plains area, this extensive alluvial plain is deposited where the Tukituki, Ngaruroro and Tutaekuri Rivers converge. Groundwater for the main aquifer system is primarily sourced from the rivers, and is generally unconfined in the west and becomes increasingly confined to the east. The sediments underlying the Irongate Industrial Area are unconsolidated Quaternary alluvium. There is a deep well, Well No (Equestrian Lane) located approximately 2km to the west that extends to 114m. This well indicates that the alluvial aquifer likely extends to considerable depths below the Irongate Industrial Area. The study area is located within the Longlands/Pakipaki Groundwater Zone as defined by HBRC. The eastern boundary of the industrial area extends along the true right bank of the Irongate Stream, but the western boundary is up 810m to the west of the stream. Information on the geology and hydrology within this area and in particular with relation to the Irongate Stream is the subject of a number of reports held by HBRC. A NW-SE trending cross section prepared from numerous well logs indicates gravel from the surface in the NW and an increasing depth of clay rich sediments along the section line towards the SE. Historic static water levels (HSWL) recorded for most of these wells show a definite trend from water-table or sub-artesian in the north-west to flowing artesian in the south-east that corresponds with an increasing depth of shallow clay confinement (EAM, 2011). The Irongate Stream is a spring fed stream that has a long history of recorded flow data. The HBRC continuous gauging site Clark s Weir is along the eastern boundary of the study area, the location is shown in Figure 2. The Irongate Stream rises approx. 2.5km to the north-west beyond Portsmouth Road. The stream flow is relatively small with significant flow gains only occurring where it crosses the State Highway along the northern boundary of the industrial area. The industrial site extends from this point approx. 1.5km due south. The flow gains are a result of storm water contributions from the urban areas of Hastings/Flaxmere, shallow soil drainage and increasing artesian pressure resulting in diffuse seepage and/or possible spring discharges. However, as the shallow clay confining layers increase in the south and east of the area the probability of spring discharges lessens and any diffuse seepage component will be reduced. Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 2

3 FIGURE 2: LOCATION OF SITE AND IRONGATE STREAM Approx. Irongate Industrial Area Irongate Stream 3.0 SUPPLY AQUIFER CHARACTERISTICS A recent application was made to HBRC for an irrigation water permit abstraction from Well No (200mm dia). This well is located in the south of the industrial site and is on the Tumu Timbers property at New Zealand Map Grid (NZMG) coordinates E , N The well was drilled in 2007 by Baylis Bros Limited it is 200mm in diameter and extends to a total depth of 35.7m. The well is screened from 34.42m to the base of the well. There is no recorded static water level (SWL) but the well is described as flowing artesian. The new application was for the irrigation of 10Ha of pasture and crops at a maximum rate of 30L/s with a 28day volume of 15,684m 3 and a seasonal volume of 69,022m 3. The consent WP was granted on 22 January It is noted that this well also supplies residential use and holds consent WP120364T for general timber treatment plant use. The maximum rate of the existing abstraction for this industrial take is 4.9L/s (423.36m 3 /d) with volumes of 525m 3 /week and 27,300m 3 /year. A number of other consents in the area were reviewed: WP030068T Max Rate 25L/s, 1,986m 3 /week, Well No.3043; WP040295Tb Max Rate 32L/s, 6,937m 3 /week, Well No. 2349; WP070103Tb Max Rate 23/s, 9,473m 3 /week, Well No & 16532; and WP980285T Max Rate 20L/s, 10,100m 3 /week, Well No The average weekly consumptive use for the Irongate Industrial Area is 8,280m 3 this falls within the existing consents. The peak rate at 58L/s is a bit higher than the existing consents. Details of the supply wells for these consents are provided in Table 1. All of these wells show positive artesian (flowing) conditions. They all have considerable thicknesses of shallow clay or predominantly clay (with some silt and sand) to depths generally greater than 30m. All of the wells terminate between 35m and 46m in depth and all end within a gravel lithology. This information indicates that the wells in this area have significant confinement and that the full depth of the existing aquifer is not screened. It is also noted that most of the wells are only 100mm diameter with the largest diameter well at 200mm. Increasing the well diameter and lengthening the well screens is expected to permit higher flow rates from the aquifer. At present the highest consented flow rate from the wells reviewed is 30L/s plus 4.9L/s from a well located within the Irongate Industrial Area. This flow rate and the volumes consented indicate Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 3

4 that installing a well within the industrial area is likely to yield sufficient rate and volume to supply the consumptive abstraction requirements. With regard to the firefighting requirements it is considered likely that the installation of a single well with a larger diameter (300mm) and extending the depth to the order of 50m, there by exposing a longer section of aquifer, is considered likely to achieve the 100L/s flow rate requirement. TABLE 1: SUMMARY WELL DETAILS FOR NEARBY CONSENTED WELLS Well Eastings Northings Dia. (mm) Depth (m) Screen top (m) Screen bottom (m) SWL (m) ve ve ve 4.0 ASSESSMENT OF ENVIRONMENTAL EFFECTS Preliminary consideration is also given to the potential environmental effects that would be associated with an application for resource consent for groundwater abstraction at this location. 4.1 GROUNDWATER-SURFACE WATER INTERACTION There is no available surface water allocation from the Irongate Stream and the potential for groundwater surface water interaction is an important consideration. As noted previously a recent application was made to HBRC for an irrigation water permit abstraction from Well No (200mm dia). This well is located within the Irongate Industrial area on the Tumu Timbers property at New Zealand Map Grid (NZMG) coordinates E , N Details of the well are provided in Table 1, it was drilled in 2007 by Baylis Bros Limited it is 200mm in diameter and extends to a total depth of 35.7m. The well is screened from 34.42m to the base of the well. There is no recorded static water level (SWL) but the well is described as flowing artesian. The lithology log describes blue silt to 3.5m depth, there is shallow water bearing gravel layer from 3.5m to 9m depth. This is underlain by puggy blue clay with silt to 14m and water bearing sand from 14m to 22m. There is a second puggy blue clay from 22m to 33m depth and the supply aquifer is blue/brown gravel from 33m to 35.72m. This description supports the flowing confined conditions described previously and the screen depth and multi-level aquifer sequence means it is highly likely that there is significant hydraulic separation between this well and the surrounding surface water. This information was considered sufficient in relation to the groundwater-surface water interaction for the granting of WP on 22 January Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 4

5 4.2 SURROUNDING WELL DETAILS For the purposes of this report existing well information was reviewed to determine the likelihood of surrounding adverse well interference effects occurring as a result of a new industrial take. During the investigation of the previously discussed groundwater take for Well No. 5615, a 2km radial well search was requested from HBRC and centred on the well. The details provided include: the surrounding well depths; distances; static water levels (SWL); and use. A plan of the surrounding wells is provided as Figure 3. The reported well analysis information showed a total of 216 recorded wells within 2kms of Well No Half of these 108 wells or 50% were unconsented. The majority of the remaining wells 63 or 58% were consented for irrigation only. There are a large number of frost protection takes, 33, and only a small number of potable supply or wash water takes. Wells most likely to be affected are those operating at the same time as any new take which in this case could potentially be all of them as it may operate year round. However, when it comes to well interference shallow wells are particularly sensitive, because they have less available head to support abstraction and therefore may not be able to accommodate additional well interference. Within the 2km radius of Well No there were 5 wells identified as <10m deep, but only 3 of these are within 500m, Figure 4. These three wells are used for environmental monitoring only. Excluding these three wells, the next nearest well that is less than 34.5m depth is 623m away, Well No The vast majority of surrounding wells 161 are greater than 30m deep. There are 22 with no recorded depth data, which means only 33 wells or 15% of the wells within 2kms are known to be <30m depth. FIGURE 3: MAP OF SURROUNDING WELL LOCATIONS WITHIN 2KM Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 5

6 Existing aquifer test data was reviewed and the Transmissivity (T) values indicated for this area are very high in the order of 10,000m 2 /d with Storativity (S) values of the order of which is consistent with a value expected for confined conditions. On the basis of the high T values a relatively small magnitude of well interference would be expected. When this is considered along with the depths of surrounding wells generally being greater than 30m, it means that adverse effects would not be expected and would likely be considered less than minor. FIGURE 4: DEPTH & DISTANCES OF SURROUNDING WELLS 4.3 AQUIFER SUSTAINABILITY It is important to consider the long term sustainability of an aquifer. This is best achieved through regional scale modelling to determine a figure for sustainable yield. There is currently no regional scale aquifer model for the Heretaunga Plains but this is currently under development by HBRC. Once developed the sustainable yield is best managed as a seasonal or annual allocation limit. The inclusion of a seasonal volume within any new water permit consent document is expected and reflects current best practice. 5.0 CONCLUSIONS A requirement for resource consent to take groundwater is expected for the consumptive use only. The firefighting abstraction would be considered as a permitted take under the RRMP. The site is located within the Heretaunga Plains aquifer area and is within the Longlands/Pakipaki groundwater zone. Surrounding well logs indicate the presence of economic aquifer units at depths of +30m. Lithology logs demonstrate multiple aquifer and aquitard sequences with SWLs from the main aquifer exhibiting flowing artesian conditions. It is anticipated that an optimal well location would be in the south to south east of the industrial area. Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 6

7 There is a nearby spring fed stream, known as the Irongate Stream. However, the overall potential contribution to stream depletion from abstraction from wells +30m deep is expected to be delayed and widely distributed. Therefore, potential effects on surface water associated with a new industrial take in this area are expected to be considered less than minor. The high T values and resultant likely small magnitude of well interference combined with the depths of surrounding wells generally being greater than 30m means that no adverse effects are expected. The potential for adverse surrounding well effects for a new take in this area are therefore also likely to be considered less than minor. Aquifer sustainability for a new consent would be managed through the allocation of a seasonal volume and this is deemed appropriate. Yours Sincerely Susan Rabbitte MSc BA(Hons) DIC Principal Geologist-Hydrogeologist References: Earth In Mind (2011) Hasting-Flaxmere Public Water Supply: Groundwater Resource Analysis to Support Assessment of Environmental Effects for Hasting District Council Prepared by Mark Gyopari Environmental Assessments and Monitoring Limited (2011) Aquifer Test Report and Assessment of Environmental Effects Well Bore Number: Portsmouth Road, Flaxmere, Hastings, Hawke s Bay. Ref: EAM261a Prepared By Susan Rabbitte Lattey Group (2015) Water Permit Consent Application 1229 Maraekakaho Road, Hastings (WP150343T). Prepared by Susan Rabbitte. MWH (2009) Irongate Industrial Plan Change Water Services Assessment Rabbitte Geoscience Limited (2012) Water Permit Application Frost Protection Assessment of Environmental Effects For Well No , 301 Portsmouth Road, Hastings. Ref: RGL121-REP-01. Prepared By Susan Rabbitte Lattey Group, 1018 Manchester Street, PO Box 4120, Woolwich. Page: 7