Refurbishment broadens the sustainability horizons of Highlands and Islands pond

Andrew Cooper, Lining Sales Manager from Firestone Building Products, discusses the pond refurbishment carried out at Horizon Scotland, a business incubator at Highlands and Islands Enterprise’s flagship Enterprise Park Forres in Moray.

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eveloped by Highlands and Islands Enterprise as an innovative and flexible business location, Enterprise Park Forres is far from a standard collection of office buildings, car parking and grass verges. Set in 100 acres of beautifully landscaped, sustainable grounds, it was established as a supportive and collaborative commercial location where companies can grow and contribute to the diverse economy of Scotland’s largest and most sparsely populated region.

Amongst the key developments at the park is Horizon Scotland, which combines 12,000ft² of office space with meeting room and conference facilities in a low-carbon building.

Horizon Scotland’s aspect is as attractive as its philosophy with a green roof, cottage garden-style landscaping and a pond that wraps around the building, all creating an exceptional work environment designed to connect the building to its geographic context. However, when the pond’s original clay lining system began to fail, water began leaking away impacting on the appearance of this showpiece development.

Highlands and Islands Enterprise issued a tender for a pond refurbishment to rectify the landscaping issues and the resulting project, using GeoGard EPDM – an elastomeric synthetic rubber geomembrane from Firestone Building Products – has transformed the feature; enhancing its aesthetics, increasing its service life and enabling it to become a catalyst for biodiversity.

Restore and enhance

The pond at Horizon Scotland was originally built when the building was constructed in 2003. For the first year following construction, the bentonite clay matting worked well, but it soon began to allow water to seep through the pond bed, causing the water to level to drop. The reduced water levels were initially managed by topping up the water, but this was both uneconomical and at odds with the environmental ethos of Enterprise Park. Consequently, the pond was allowed to drain and Highlands and Islands Enterprise decided on a refurbishment.

The project was put out to open tender, with the stipulation that the chosen pond lining system would have a guaranteed leak-free service life of at least 12 years, and Biomatrix Water, a tenant at Horizon Scotland and a specialist in floating ecosystems and waterway restoration, was awarded the project.

While pond refurbishments are not Biomatrix Water’s core business, the company recognised an opportunity to design a scheme that would address the leakage problems while enhancing the water quality with improved natural flow. The design team also aimed to nurture biodiversity with natural habitats.

Biomatrix scoured the marketplace for a suitable solution and selected Firestone’s GeoGard EPDM for the lining because it has a proven service life of at least 40 years, excellent flexibility and puncture resistance and would be able to cope with the level of detailing required. The company was also aware that Firestone offers comprehensive installation training and Firestone’s technical team visited Forres to deliver training on site following the contract award.

Remodelling

Having designed and specified the project, Biomatrix Water worked with specialist contractor, Water Gems, to deliver the pond refurbishment. The remaining water, mud and vegetation was removed, and the cobbles that had been used on the pond bed were removed and cleaned for re-use in the refurbishment. A JCB and mini digger had to be deployed to cut through the original hard clay surface to remove it, revealing a soft, sand substrate that could be shaped to the requirements of the remodelled pond.

Biomatrix Water’s vision for the pond included increasing its size and changing its shape, retaining the glass and wooden bridges already in place while enhancing the water quality with the addition of a cascade to aerate the water. The plans also included supporting biodiversity by introducing a floating island.

The level of detailing in the original pond had contributed to the failure of the clay lining system, and the new pond layout required even greater levels of detailing, particularly around the cascade that was so central to the new design, and around the bridge footings. However, despite being only 1.5mm thick, the GeoGard EPDM system is very strong and flexible with excellent tear and puncture resistance. This flexibility means the lining adapts and conforms to irregular substrates and lays flat with no voids beneath, making it ideally suited for complex detailing. Moreover, GeoGard EPDM’s capacity for elongation by over 300% in all directions ensures that the lining will not be damaged during installation or by any post-installation movement.

Collaborative approach

Firestone worked with Biomatrix Water to configure the layout of the lining installation to optimise the use of the GeoGard EPDM material and minimise waste.

Following excavation of the new pond layout, two tonnes of backfill was arranged onto the soft sand substrate and compacted twice to provide a robust, smooth surface. A 500g/m2 geotextile layer was then laid onto the pond bed to protect the GeoGard EPDM, and the 1.5mm GeoGard EPDM was installed, using Firestone’s QuickSeam Splice Tape to seal the joints between sections of membrane and QuickSeam FormFlash for the varied detailing elements.

With the lining in place and covered with a further layer of geotextile to protect it, the project team returned the cleaned cobbles to the pond and added gravel, obscuring the lining and providing a natural-looking waterbed. Pipework to take additional filtration to the cascade was also obscured in the gravel. Extensive planting was then carried out, including the creation of an island, which provides a habitat for wildfowl above the water and a microorganism habitat below the waterline amongst the roots of the island’s planting.

Long-term benefits

The project has not just reinstated the pond but has dramatically improved it, adding to the biodiversity and sustainability that have always been so central to the aims of Enterprise Park. Thanks to the service life of the GeoGard EPDM membrane and the water quality improvements introduced to the feature, the pond will continue looking great and enhancing the work environment with minimal maintenance for many years to come.

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