The site for the proposed Ark data centre is overdevelopment says the Letchmore Heath Village Trust. It’s entirely in the green belt, although contains partly previous developed land utilised by the Mecure Hotel.
Now renamed the Hilfield Centre, it's allocated as employment land in both the previous and emerging Local Plan. Planning permission was granted for the whole site for a 30,000 sqm Class B8 warehousing scheme. This expires in March.
Since then the revised NPPF requires planning authorities to plan positively for data centres and has also introduced the concept of grey belt. In their planning submission, Ark have put forward both a grey belt case and a green belt case for development.
The site will be entirely built upon with removal of most open space. Almost lmost half the frontage to the A41 is currently open land which maintains the semi rural nature of the A41.
Total floor space proposed is 137,410 sqm, over 4.5 times both the current warehouse permission. With a height of 36.25m, it represents a massive overdevelopment of the site.
The proposal consists of the demolition of all the existing buildings to be replaced by the following:
- Four data centre buildings in individual secure compounds with separate parking and service yards. Three of these will be similar in terms of scale and massing, the fourth, parallel to the site’s boundary with the Sandy Lane HCC Traveller Site, will have a reduced footprint. Each will be 36.25m (119 ft) high plus a ventilation stack taking them to 38.95m (128ft) Facades to be horizontal metal louvre or perforated metal cladding
- Two substations - 11 m high (36 ft)
- Visitor Reception Centre - 20 m (66 ft) high, located centrally
- Three vehicular access points. Two, as existing, from the A41 and one from Sandy Lane further east, away from the current signal-controlled junction. The Sandy Lane access and the southern vehicular access along the A41will be restricted to emergency use.
- Energy to include back up generators, power, and water infrastructure
- Site access and internal roads
- Security fencing - 4m high (13ft) topped by 1m anti climb razor wire
The major concern with the development is the height and visual impact. It is simply too large in terms of scale and intensity. The proposal is also inappropriate for this site when assessed against planning criteria. At over four times the size proposed in the existing and emerging local plan it hugely exceeds the capacity of the site to accommodate it without causing harm to its surroundings. There are also concerns regarding overshadowing the adjacent travellers site; its impact on nearby heritage assets, the nearest being Tylers Farm and detracting from the rural aspects of the A41.
Ark state the proposal was originally for more linear, lower buildings, but that the current proposal was formulated after extensive pre-app with Hertsmere Borough Council.
A full assessment of the scheme by Janet Engels of the Letchmore Heath Village Trust can be found here
Full reasons for refusal can be found here.