Construction of the New FlexGrass Playing Surface at AIL Arena – FC Lugano
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By FlexGrass
Lugano in Switzerland is not your average City; you could not paint a more perfect backdrop, with Monte Bre towering on one side and Lake Lugano on the other. It is in this setting that stadium architects were tasked in constructing a stadium that not only utilised sparsely available flat land but celebrated its surroundings. FlexGrass were selected to be part of this team, building what is a truly unique stadium in one of the World's most stunning locations.
In April 2025, FlexGrass officially commenced work on the construction of the new playing surface at AIL Arena, the future home of FC Lugano. This high-profile sports construction project forms part of its new stadium that reflects the ambitions of the Ticino-based club.
For FlexGrass, it represented an exciting technical challenge: delivering a next-generation hybrid grass pitch within an extremely compressed timeline, while meeting international construction and agronomic standards.
44 Days to Complete the Sub-Base
Just 44 days after breaking ground, all structural sub-base works were completed: from the primary drainage system to the installation of the gravel carpet, from the FlexHeat undersoil heating system to the FlexAqua automated irrigation system, followed by construction of the USGA-compliant rootzone profile.
The excavation level was set at –45 cm relative to finished pitch level, a depth precisely calculated to accommodate the full construction profile while ensuring structural stability and optimal hydraulic performance.
Drainage System and Gravel Carpet
Following trench excavation across the pitch, longitudinal drainage lines were installed — a key component for water management in a high-performance sports field.
Linear drains were installed at 5-metre intervals with a 0.5% gradient, accurately surveyed, and laser-graded to guarantee millimetric precision. The drainage trenches were backfilled with selected, high-permeability drainage gravel.
Above the drainage lines, a continuous 15 cm gravel carpet layer was installed, using washed gravel graded to a four-way crown specification. This layer forms the core of the pitch drainage system, allowing rapid lateral water movement toward the primary drains, preventing surface waterlogging and ensuring consistent load-bearing capacity even in adverse weather conditions.
Simultaneously, the main trench for the heating system manifold was constructed, allowing for installation of the primary pipework of the FLexHeat system.
Integrated Pitch Technology: Irrigation and Undersoil Heating
The FLexAqua irrigation system includes 35 pop-up sprinklers, positioned according to a layout designed to ensure high distribution uniformity (high CU value) and full surface coverage. Pipework was installed directly within the gravel layer, with particular attention to protection of the lines and ease of future maintenance.
At the same time, the FLexHeat undersoil heating and cooling system was installed. Heating pipes were laid on the gravel base and connected to the previously installed main manifold.
This system enables precise control of rootzone temperature, preventing winter frost, promoting early-season recovery, and providing the grounds professional with a strategic agronomic management tool throughout the year.
USGA Rootzone Construction
The first 20 cm sand layer was constructed using USGA-specification silica sand (0–2.5 mm particle size distribution). This layer was laser-levelled following the same four-way crown geometry to ensure structural continuity.
The final 10 cm finishing layer consisted of finer 0–2 mm sand, selected to optimise surface smoothness and playing quality. This layer was amended with 10% selected compost to increase organic matter content, improve cation exchange capacity (CEC), and optimise rooting and establishment conditions.
The result is a stable, highly permeable rootzone with an excellent balance between drainage and moisture retention — an ideal agronomic platform for professional turf management.
Seeding and Establishment
Flex Grass as part of the construction also took on the grow-in and early maintenance. Approximately seven weeks after the start of construction, following completion of final grading and performance testing of the profile, the pitch was declared ready for seeding.
Seeding was carried out in early September, within an agronomically favourable window, avoiding summer heat stress and reducing the risk of high-temperature fungal diseases.
Approximately 200 kg of a pure blend consisting of two Poa pratensis cultivars was applied using a dimple seeder to ensure uniform distribution and correct sowing depth.
The decision to use Kentucky bluegrass (Poa pratensis) instead of perennial ryegrass (Lolium perenne) was driven by strategic timeline considerations. With sufficient establishment time available prior to handover, we opted for a slower-establishing species, that at maturity, provides superior rhizomatous density, enhanced mechanical resilience, and improved summer heat tolerance.
Germination occurred approximately 10 days after seeding. A nitrogen-dominant nutritional programme was implemented to stimulate vegetative growth and leaf development.
Foliar applications of liquid fertilisers and biostimulants (amino acids, seaweed extracts, and micronutrients) were integrated to optimise metabolic activity and support root and shoot development.
A high-phosphorus starter fertiliser was applied at seeding to promote early rooting and seedling development followed by split nitrogen applications to sustain turf density.
Due to the fully sand-based profile, irrigation management required 4–5 short cycles per day to maintain consistent surface moisture while preventing excessive percolation.
Conclusion
The AIL Arena project represents a benchmark example of integration between pitch construction, infrastructure technology, and specialist agronomic management.
The result is a high-performance hybrid grass pitch designed to deliver mechanical stability, durability, and optimal playing standards; a new professional stage for FC Lugano, built on solid technical and agronomic foundations.
