Assets & Services Committee Meeting
27 November 2019
This Report relates to Item 13 in the Agenda
“Lansdowne Park Sports Field Condition Assessment”
Lansdowne Park sports field condition assessment
Client: Marlborough District Council Date: October 2019
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Contents
1.0 Executive Summary ...... 3 2.0 Background ...... 5 3.0 Sports field assessment ...... 6 3.1.1.1 Key sports field data: ...... 6 3.1.1.2 Sports field surface infiltration and compaction ...... 7 3.1.1.3 Organic matter (%) of top 75 mm ...... 8 3.1.1.4 Soil nutrient analysis of the sports field ...... 9 4.0 Conclusions ...... 18 5.0 Options for sports field upgrade or enhancement ...... 20-24 6.0 Recommendations ...... 25-26
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1.0 Executive Summary
The key findings of the sports field assessment of Lansdowne Park were: 1. The current turf surface is ryegrass dominated with a high percentage of well dispersed Poa annua within the sward. There did not appear to be a seed head control programme in place regarding the Poa annua.
2. No significant issues relating to surface compaction or surface infiltration rates were identified as part of the assessment. The surface achieved the minimum requirement of 50 mm/hr surface infiltration (RWC11 Guidelines).
3. The existing soil profile consists of a sandy/silt topsoil that is prone to waterlogging following prolonged periods of rainfall. This soil type also has a poor physical structure and will be relatively high leaching in terms of moisture and nutrients throughout the drier summer months.
4. The existing surface levels were described as being ‘Poor’ for a premier sportsfield. A significant amount of variation was observed in surface levels. There appeared to have been settlement in localised areas of the field. Note: Such settlement is consistent with constructing a sports field from a sand/silt dominated soil.
5. No significant issues were identified through the soil nutrient analysis of the sports field.
6. The existing organic matter % content within the top 25 mm of the profile meets the ‘Desired level’ for a sand/soil-amended natural turf sports field. However, all other horizons exceeded the ‘Desired range’.
7. The average organic matter % content of the top 75 mm profile was in excess of the ‘Desired range’.
8. In consideration of the above factors, the current sports field construction significantly limits any future desires from MDC or Community stakeholders to increase the utilisation or usage of the surface beyond that which it is currently subjected to.
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Based upon NZTMS’s experience and in-house Research & Development in relation to natural sports turf surface performance, the recommendation is to carry out the following programme of works upgrade:
1.1 Carry out a CCTV inspection of the existing primary drainage system to ensure absolute confidence in its operational performance 1.2 Removal of the top 50 mm of existing surface 1.3 Replacement (or clean out) of the existing primary drainage system¹ 1.4 Installation of a new automated irrigation system 1.5 Installation of a 100 mm deep amended sand carpet: (NZTMS recommends a 90% [sand] 10% [vermicast] blend). 1.6 Installation of sand slits at 500 mm centres (Potential to stage this: could be initially installed at 1 m spacings and decreased to 500 mm spacings in year 2) 1.7 Seed with ‘Super Strike’ ryegrass variety 1.8 Grow-in
¹ Pending the results of a CCTV inspection
NZTMS does not recommend the installation a hybrid turf system at Lansdowne Park unless a robust business case can be made regarding increased utilisation of the playing surface for high level sport as well as increased booking for multi-functional events such as festivals, community events and concerts etc. Hybrid technology offers an excellent solution for a natural sports surface to better withstand adverse wear and tear and multi-use, however the significant additional cost of installing this product needs to be justified by the future forecasted utilisation of the venue.
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2.0 Background
On the 17th October, 2019 New Zealand Turf Management Solutions (NZTMS) was engaged by Marlborough District Council (MDC) to carry out a site visit to the Lansdowne Park Stadium (Blenheim) and provide an independent sports field condition assessment of the existing playing surface. During the site visit a number of key performance factors were measured in order to quantify the current playing performance of the sports field as well as drive recommendations relating to the future enhancement of the sports field. The measurable performance factors were: 1. Organic matter accumulation (% Organic matter in the top 75 mm of the profile) 2. Soil nutrient status 3. Key soil profile characteristics (description of soil type) 4. Surface infiltration (the rate at which water drains away from the playing surface) 5. Surface turfgrass species composition, weeds, pests and plant density 6. Surface compaction 7. Gravel band inspection
This report provides MDC with a summary of the key findings relating to key performance factors (1) to (7). In addition, the report provides applied interpretations of this data that has been used to develop costed options for the potential future enhancement of the site.
Figure 1: Lansdowne Park in preparation for the 2019 Mitre 10 Cup semi-final
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3.0 Sports field assessment
This section provides details of all of the findings and observations captured by NZTMS during the site visit.
3.1.1.1 Key sports field data:
Visual assessment criteria Comments Score (1-5) ¹ Grass species Perennial rye grass Poa annua 4
Weed species Less than 2% estimated broad leaf weed presence 5
Dominant soil characteristic in Silt dominated loam (prone to de- top ≥100 mm of profile structuring and compaction) 3
¹ Scoring system:
1= ‘Extremely poor for time of year’
2= ‘Poor for time of year’
3 = ‘Acceptable for time of year’
4 = ‘Good’ for time of year’
5 = ‘Excellent for time of year’
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3.1.1.2 Sports field surface infiltration and compaction
Surface infiltration (mm/hr) Surface infiltration analysis was conducted using a double-ring infiltrometer.
Locations Measurement mm/hr (1) to (5) infiltration Average 53
RWC11 Guidelines require a ‘premier’ sports field to attain a rate of surface infiltration of: minimum 50 mm/hr.
Surface compaction (PSI) A 15-point analysis of the surface was conducted using a hand held Penetrometer
Location Measurement (PSI) Average 58
Good growing conditions (<100 psi)
Fair growing conditions (100-200 psi)
Poor growing conditions (>200 psi)
No issues regarding surface infiltration rates or surface compaction were identified
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3.1.1.3 Organic matter (%) of top 75 mm
Depth Dry weight (g) Burnt weight (g) OM % (mm) Content 0-25 159.65 135.45 15 25-50 233.69 207.59 11 50-75 217.56 198.54 9 Average Organic mater % content of top 75 mm 12%
Above desired value Slightly above desired value Meets desired value
Interpretation: 0-25 15.0% 25-50 9.0% 50-75 7.0% Average 10.3%
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3.1.1.4 Soil nutrient analysis of the sports field
Soil Nutrient Analysis Report NZTMS Analytical
Lansdowne Park M: 027 285 5029 E: [email protected]
1.0 Scope of Analysis
This report provides an independent interpretation of Photo the soil nutrient analysis report carried out by Hill Laboratories. NZTMS has interpreted the results against the appropriate soil and turf species parameters.
2.0 Quick reference dial interpretation
Potassium Phosphorus Calcium
Value Value
PointerValue 781 60 PointerValue 301 60 PointerValue 581 End 189 18060 End 189 18060 End 189
Sodium pH CEC
Value Value Value 60 60 Value 55 60 Value 60 EndPointer 1891 60 EndPointer 1891 60 EndPointer 1891 180 180
Dial Interpretation:
Below ' Optimum' range Within 'Optimum' range Above 'Optimum' range (not a concern unless Sodium)
4.0 Recommendations & Calculated deficits
Within this section of the report, only those factors that have been identified as being 'outside of the 'Optimum range' have been specifically identified.
No significant deficits or issues relating to the nutrient content of the soil sampled was identified. NZTMS recommends that the current nutrient management programme should continue on this field.
A deficit - 5 Kg/Ha of Phosphorus was measured. This does not represent a significant deficit and can be relatively easily rectified via an application of balanced NPK slow release fertiliser such as: 12-5-12 at 200 Kg/Ha.
5.0 Certification of Report
Analysis Certified by: Date: 22/10/19 Will Bowden Manager New Zealand Turf Management Solutions
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3.1.1.5 Key soil profile characteristics The dominant soil characteristic of the profile at Lansdowne Park is that of a sandy/silt- dominated loam material. This is best shown on the exposed embankment behind the stadium where widening of the stream is taking place (figure 2b):
a b
Legend: Aw= Awatere, Gb = Wairau soils
Source: Soil maps – Masterton District Council, 2019
Figure 2: Typical soil characteristic of on-site profile.
These soils are ’light’ in structure and have a tendency to be high leaching. The stadium field is somewhat of a modified version of the naturally occurring surrounding soil types (as shown in figure 2). However, the extraction of cores down to a depth of > 150 mm identified a similar type of soil within the stadium as those described in the local vicinity. These soils are inherently ‘poor’ in terms of their structure and their limited ability to resist deformation when subjected to high wear or compaction (especially when saturated).
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Figure 3: Existing soil structure within Stadium. Modified sandy/silt loam
Within the top 40 mm of the profile significant worm activity was observed, particularly towards the embankment end of the field although this did not equate to a proliferation of worm castings on the surface of the field.
Figure 4: Earthworm activity observed within top 40 mm of the profile.
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The typical order of the existing profile structure at Lansdowne Park is described in figure 5:
20 mm organic matter layer (generally well diluted)
Sand/silty loam horizon
Poor structure
Increasingly silty and moving toward less structured soil
Figure 5: Description of the existing soil profile on the sports field
The dominant soil characteristic of a sandy/silty material does not align with a high performing infiltration or air-filled porosity characteristic. Soil structures that are dominated by ‘fine; material, have a predisposition to compaction resulting in associated poor drainage performance during period of prolonged wet weather (i.e. a tendency to become rapidly waterlogged). Alternatively, during periods of dry weather these poorly structured soils become ‘dusty’ and prone to hydrophobicity relatively quickly.
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During the extraction of cores and assessment of the existing soil profile, NZTMS noted that in some areas of the field turfgrass root systems (most likely those of ryegrass) had extended down to a depth of > 130 mm. This represents an impressive depth of roots for the time of year and is likely due to aeration practices as well as the limited ability to apply water to the field during the year. These factors combined will result in a deeper rooting turfgrass plant.
Figure 6: Turfgrass roots measured at > 130 mm depth in some locations.
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3.1.1.6 Turfgrass species composition
The dominant turfgrass species on the sports field was ryegrass (Lolium perenne var: Colosseum) Poa annua was also widely dispersed throughout the sward. The turf sward was in ‘good’ condition with excellent density and colour on the day of the NZTMS visit. No broadleaf weed species were observed on the field.
a b
Figure 7: Excellent turf density observed on the surface of the sports field. 7b: Poa annua observed seeding across the field.
The Poa annua plants were seeding across the field and intermingled throughout the (preferred) ryegrass sward. Whilst Poa was prevalent across the site there were no large plates of exclusive Poa annua grass visible. The dispersal of Poa was spread throughout the rye grass constituent of the sward. This will be beneficial in terms of the existing surface’s overall resistance to wear. Where Poa annua was dominant, there was a noticeable deterioration in the quality of the surface. These areas tended to be those of highest wear and intensive use. Ironically in high wear areas where the ryegrass becomes stressed and thinned, Poa annua is the first turf species to colonise. Unfortunately, Poa annua is also the first turfgrass species to become
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damaged by wear and tear on the surface, due to its comparatively shallow root systems and upright tufted growth habit. The areas with the highest Poa annua composition were the worst divotted.
Poa annua
Poa annua
Figure 8: Showing areas of Poa annua in the sward around areas of worst divot-damage on the surface.
Figure 9 shows an example of a Poa annua plant that was collected during the NZTMS surface assessment. The average root depth of this plant is around 30-35 mm. This compared to an average root depth across the field of around 80-100 mm (predominantly the ryegrass plants)
Figure 9: Poa annua plant
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3.1.1.7 Gravel band inspection NZTMS understands that approximately 2 years ago gravel bands were installed across the field by ‘Mexteds Performance Sports Surfaces’. These appear to have been installed as per the generally accepted specification of 25mm width, 300 mm depth and at 400 mm centres. NZTMS was unable excavate the full depth of the gravel bands due to the upcoming ‘Mitre 10 Cup’ Semi-final, however an inspection of the top 150 mm or so of representative gravel bands was carried out using a 40 mm diameter corer.
Organic layer 20 mm
Relatively ‘clean’ gravel material with turf root migration
Increasingly contaminated and ‘non-functional’ gravel band material
Figure 10: Gravel band to 120 mm depth
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Figure 11: Close up of the top 40 mm of a gravel band at Lansdowne Park.
Figure 11 shows how throughout the top 40 mm (or so) of the existing gravel bands the material was relatively ’clean’ and the gravel had remained reasonably free draining and effective as a medium for surface water to travel through. The issue arose at the 80-100 mm horizon. In all of the observed gravel bands this horizon had become contaminated with silt and soil material from the surrounding profile. The operational effectiveness of the gravel bands below this level was described as being ‘poor’ with severely limited ability to facilitate the downward percolation of water through to the lower portion of the gravel band and into the underlying primary field drain beneath.
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4.0 Conclusions
Based upon the findings of the on-site investigation and the associated analysis, the following conclusions have been provided:
9. The current turf surface is ryegrass dominated with a high percentage of well dispersed Poa annua within the sward. There did not appear to be a seed head control programme in place regarding the Poa annua.
10. No significant issues relating to surface compaction or surface infiltration rates were identified as part of the assessment. The surface achieved the minimum requirement of 50 mm/hr (RWC11 Guidelines).
11. The existing soil profile consists of a sandy/silt topsoil that is prone to waterlogging following prolonged periods of rainfall. This soil type also has a poor physical structure and will be relatively high leaching in terms of moisture and nutrients throughout the drier summer months.
12. The existing surface levels were described as being ‘Poor’ for a premier sportsfield. A significant amount of variation was observed in surface levels. There appeared to have been settlement in localised areas of the field. Note: This is consistent with constructing a sports field from a sand/silt dominated soil.
13. No significant issues were identified through the soil nutrient analysis of the sports field.
14. The existing organic matter % content within the top 25 mm of the profile meets the ‘Desired level’ for a sand/soil-amended natural turf sports field. However, all other horizons exceeded this range.
15. The average organic matter % content of the top 75 mm profile was in excess of he ‘Desired range’.
16. The current sports field construction significantly limits any future desires from Council or Community stakeholders to increase the utilisation or usage of the surface beyond that which it is currently subjected to.
An explanation of this has been detailed as follows:
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Figure 12 provides a diagrammatic interpretation of the current issue regarding the performance of the existing soil profile and gravel band drainage system at Lansdowne Park. From our investigations NZTMS identified a zone through the gravel bands at around the 80- 100 mm horizon (refer to figure 10) that has become contaminated by soil from the surrounding profile. This has led to the issues identified in Figure 12:
GRAVEL BAND:
[Top 50 mm] Relatively ‘clean’ gravel.
GRAVEL BAND: [80 -100 mm] Increasingly contaminated gravel.
Lateral water movement
Due to contamination of the gravel band and the silty nature of the surrounding soil, water that has infiltrated through the surface and into the gravel band cannot move downwards towards the
field drain. Instead, this water moves laterally at the 80-100 mm depth and ‘fills up’ the soil profile from below until field capacity is reached.
Figure 12: Contaminated gravel band. The existing system can cope with ‘short’ ‘sharp’ rain events; however, it will not be able to cope with periods of prolonged wet weather or intermittent regular heavy rainfalls. The finess of the dominant silt characteristic of the soil profile means that pore spacing within the soil profile is reduced and consequently the ability of water to naturally percolate through the profile is limited. The drainage system cannot facilitate a fast-enough rate of drainage during wet spells of weather and the profile reaches field capacity and becomes saturated. Once saturated the playability of the surface is negatively affected and the potential for the surface to compact and for the turf to ‘shear’ increases.
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5.0 Options for sports field upgrade or enhancement
As a component of this report, NZTMS has provided MDC with some high-level upgrade options for the sports field at Lansdowne Park. These fall the following range of options:
1. Construction of a new sand slit, sand carpet above either existing soil or a gravel raft base. Note: CCTV investigation of the condition of the existing primary drainage infrastructure to be carried out in order to ascertain whether or not this is fit for purpose.
2. Construction of a new sand slit, sand carpet (as per option 1) with the addition of an appropriate turf reinforcement system (e.g. ‘MOTZ’, stitched individual fibres or backed hybrid product)
3. Staged upgrade of the existing sports field over a number of years to include:
• Confirmation that the existing primary drainage infrastructure is fit for purpose • Installation of a fully automated irrigation system, • Replacement of the existing soil profile with a sand (or sand amended) profile, sand slits and re-seeding of the surface.
Note: The installation of an automated irrigation system shall be paramount as a component of any of the 3 upgrade options.
Aside from budgetary restrictions, a key driver of the decision-making process relating to the above 3 options should be usability and functionality of the sportsfield at Lansdowne Park. Is there a desire by MDC to increase the future multi-use/functionality of the surface through staging concerts, festivals and other larger community-based events at the Stadium? Where multi-functional use is a key consideration then the option of installing a reinforced turf system has increased relevance. If the likelihood is that future use of the sports field is to remain relatively consistent with its current application, and the Council wishes to offer an enhanced surface that is capable of hosting ‘premier’ sporting events and offering a generally ‘high’ level of performance then the preferred option might be to replace the existing soil-based surface with a full sand (or sand amended) carpet over a gravel raft.
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In terms of usage, NZTMS understands that the field is currently used in Winter from Mid- March to around early November, with a maximum of 46 games per season (around 55 hrs through winter) Note: this does not include training time. During Summer the field is available to Tasman football and also has 2 touch fields for 6 weeks. Over this period of time games will be played 2 nights per week, 4 games per night.
Based upon usage alone it is difficult to approximate how many hours per week the field is being subjected to. The following Table summarises the various sportsfield options that are available to MDC when considering the upgrading of the existing Lansdowne Park sports field. For the purposes of this report, all available options and associated turf system have been included, alongside an indication of budgetary detail, on-going operational costs and the various pros and cons of each.
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¹ For the purposes of this report the Sand Carpet option has been generalised into a single sports field option. A significant number of variances exist of this sports field model.
² Based upon ‘best estimate’ of current lead – in times as per supplier.
³ Based over a 10-year period expected lifespan (inclusive of all maintenance costs associated with the field.
*The comparatively large variance between lowest and highest cost for this option is due to the relatively large number of suppliers for Hybrid turf available in New Zealand. This can be discussed further by NZTMS
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6.0 Recommendations
Based upon the analysis carried out as part of the site assessment as well as a broader consideration of all other site-specific factors, the following recommendations have been provided to MDC:
2. The existing condition of the sports field at Lansdowne Park is not at an appropriate level for the regular hosting of ‘premier’ sporting events or regular multi-functional use.
This is due to a number of factors, of which the following have been identified as key:
• Poor surface levels • Excessive organic matter accumulation in the top 75 mm of the profile • Widespread dispersal of Poa annua • Tertiary drainage (gravel band system) that has reached the end of its viable lifespan • The dominant characterisation of the existing soil profile cannot meet the expectations of a high-performance sports surface, in terms of achieving the required rate of: infiltration, percolation and/or resistance to compaction required year-round. Due to these key factors NZTMS recommends that the sports field should be upgraded as follows:
2.1 Carry out a CCTV inspection of the existing primary drainage system to ensure absolute confidence in its operational performance 2.2 Removal of the top 50 mm of existing surface 2.3 Complete replacement or clean out of the existing primary drainage system 2.4 Installation of a new automated irrigation system 2.5 Installation of a 100 mm deep amended sand carpet: (NZTMS recommends a 90% [sand] 10% [vermicast] blend). 2.6 Installation of sand slits at 500 mm centres (Potential to stage this: could be initially installed at 1 m spacings and decreased to 500 mm spacings in year 2) 2.7 Seed with ‘Super Strike’ ryegrass variety 2.8 Grow-in
3. At this stage NZTMS does not recommend the need to install a hybrid turf system at Lansdowne Park unless a robust business case can be made regarding increased utilisation of the playing surface for high level sport as well as increased booking for multi-functional events such as festivals, community events and concerts etc.
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4. Hybrid technology offers an excellent solution for a natural sports surface to better withstand adverse wear and tear, however the significant additional cost of installing this product needs to be justified by the future utilisation of the venue.
Note: NZTMS has capability to provide MDC with all of the suitable documentation regarding Technical Specifications, Schedules and Project Management of physical works should this be appropriate having previously provide a similar scope of service for the following New Zealand venues:
• Christchurch Stadium • FMG Waikato Stadium (Hamilton) • Wellington Stadium • The Basin Reserve (Wellington) • Seddon Park (Hamilton) • Toll Stadium (Whangarei) • Navigation Homes Stadium (Pukekohe, Auckland) • Palmerston North Stadium
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