Practice Note for Professional Persons No. 3/2006

Landscape Treatment and/or Other Measures for Mitigating the Landscape and
Visual Impacts of Small-scale Utility Installations

Introduction

1. The purpose of the Practice Note is mainly to set out the general principles and requirements for mitigating the landscape and visual impacts of small-scale utility installations (SSUI), where planning permission is required from the Town Planning Board (TPB) for their development.
2. Depending on the zoning of an application site, planning permission from the TPB may be required for SSUI. SSUI may have, inter alia, landscape and visual impacts on the surrounding environment, especially in the rural areas. In submitting a planning application for SSUI, the applicant is encouraged to include at the outset the appropriate mitigation proposals to address the possible visual and landscape impacts of the proposed development for consideration by the TPB.
3. The TPB will assess each application individually and decide whether any landscape treatment and/or alternative mitigating proposals, if included in the planning application, are acceptable. If it is considered necessary, the TPB may impose a landscape or other suitable condition requiring the applicant to mitigate the landscape and visual impacts of the proposed installation on the surrounding environment when approving the application. In general, factors to be taken into account include size and prominence of the installation; distance to visual sensitive receivers; setting of the surrounding areas; availability of suitable land adjacent to the installation for effective planting; avoidance of underground and above ground utilities; public benefit (taking competing local needs, if known, into account); local circumstances; and effectiveness of planting in fulfilling the screening function.
4. This Practice Note is applicable to SSUI such as a package substation which generally occupies an area of not more than 12m², and similar projects of comparable size and scale. It should be noted that this Practice Note is advisory in nature, and the applicant is encouraged to submit landscape treatment and/or other alternative mitigating proposals based on actual conditions of individual site to address the landscape and visual impacts of the proposed installation. Requirements of landscape submissions for other projects are set out in Practice Note for Professional Person No. 1/2004.

    

Guiding Principles

5. The landscape and visual impacts of SSUI on the surrounding environment should be duly addressed. To cater for the circumstances of different locations, a flexible approach would be adopted in the design of the SSUI. The key guiding principle is that due consideration should be given to the integration of the SSUI with the surrounding areas and that the design of the SSUI should be commensurate and blend in with the surrounding environment. Measures to mitigate landscape and visual impacts may include landscape treatment and/or appropriate building design treatment, such as facade treatment, sensitive site planning and enhanced overall design, subject to the agreement of the TPB in consideration of the circumstances of individual application.

Landscape Treatment

6. In cases where landscape treatment is adopted, appropriate soft landscape treatment should be used to provide a vegetation screen for the installations, subject to availability of suitable land in the adjacent area for the purpose. Whether landscape screening would be required on all sides of the proposed installation and how large the soft landscape area should be would depend on the circumstances of each case, with the existing vegetation or other topographical features in the immediate vicinity of the site duly taken into account. In general, for sides already adequately screened off, no additional landscape treatment is needed.
7. Disturbance to existing trees adjacent to the proposed installation should be minimized or avoided and the proposed landscape treatment should blend in with the surrounding environment.
8. The general requirements for landscape treatment are simple and basic, with the main objective to screen unsightly land uses and integrate the SSUI into the existing landscape as far as possible. Level of maintenance varies depending on the type of planting, but in principle minimum maintenance is aimed for.
9. The scale including the coverage and height of the planting should preferably be commensurate with the objective i.e. of screening and ensuring the integration of the SSUI into the existing landscape.
10. In general, peripheral planting is the easiest and cheapest option and requires comparatively least maintenance after plants are established. Screening by climbing plants on a fence or other support frame would require a smaller space but climbing plants may have a shorter life span, and replacement of plants may be required when substantial maintenance or replacement of fence or support frame is needed.

Types of Planting

(i) Perimeter Planting

11. A continuous planting strip with a combination of trees, bamboo and shrubs can make a very effective screen. A balanced use of fast- growing and slow-growing native/exotic plants would assure a sustainable vegetative screen. Some recommended species together with the suggested minimum size and maximum spacing for planting are listed in Annex A for reference purpose. In general, trees of adequate height with shrubs are recommended so as to provide the effective screening.
12. Planting should preferably be in the ground or fixed planters with an open-bottom. If close-bottom planters are proposed, suitable means of irrigation provision should be considered. Proper subsoil drainage should also be allowed to these close-bottom planters so as to avoid excessive water retained in the planters.
13. Adequate space must be allowed to enable the plants to grow and the canopy to spread. In general, a single row of trees requires a planting strip of at least 1m wide.
14. Adequate clearance should be allowed to avoid underground services and utilities, if any. This is particularly important with regard to trees, as roots and branches can adversely affect walls, foundations and underground services. Precautionary measures such as provision of root barriers should be made if trees are to be planted close to structures or underground services. Early consultation with the concerned departments/parties is suggested. An applicant is advised to take into account his own maintenance and cable routing requirements in preparing the landscape proposal.
15. Planting of trees with very tall mature height immediately underneath overhead cables should be avoided.
16. Regular horticultural maintenance such as watering, weeding, fertilizer application and pruning, etc. should be undertaken as and when necessary so as to ensure healthy establishment of plants.

(ii) Climber screen

17. If limited space is available, consideration may be given to adopting a climber screen where climbing plants are supported on a vertical mesh frame or boundary fence of a height not less than the utility structure to be installed.
18. If the frame can be attached to the building structure, a minimum net dimension of about 0.5m x 0.5m planting pit should be required for planting individual climbing plants. If this is not possible, the frame could be erected at a minimum distance of 1.6m away from the building to allow circulation around the building but within the site boundary, and/or the frame could be incorporated into the boundary fence.
19. All climber plantings should be in the ground or fixed planters with an open-bottom. Higher level of maintenance such as regular watering will be required if climbers are planted in pots or close-bottom planters, for which a minimum net soil depth of 0.5m should be allowed.
20. The level of maintenance varies depending on the type of planting. Normally maintenance requirement will be diminished once the plants are well established.
21. Annual pruning would be required once the climbers had established to control their spread and encourage flowering.
22. Regular horticultural maintenance such as watering, weeding, fertilizer application and pruning, etc. should be undertaken as and when necessary so as to ensure healthy establishment of plants.

Alternative Mitigating Proposals

23. Alternative mitigating proposals may also be proposed for consideration of the TPB. Alternative mitigating proposals may include sensitive site planning and facade treatment, roof treatment and enhanced overall designs to minimize the visual impact of SSUI and thereby ensuring coherence with the character and setting of the surrounding environment. In cases where a landscape condition is considered necessary and imposed by the TPB, building design treatment alone will not be accepted as a means to fulfill the landscape condition.

Enquiry

24. Applicants are welcome to contact the relevant District Planning Office and the Landscape Unit of Planning Department for enquiries on any case-specific issues and special landscape matters respectively.
25. This Practice Note will take immediate effect.

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(B.C.K. FUNG)
Director of Planning
Planning Department
Date : 22 June 2006
First Issued: 22 June 2006

Annex A

Recommended Species for Use in Landscape Treatment of Small-scale Utility Installations (For Reference)

Note:
The above recommended plant species are for reference purpose only. Applicants are free to choose their preferred plant species in their landscape proposals. Selection of plants depends on site-specific circumstances, and in general a combination of trees, bamboo and shrubs can make a very effective screen.

 

Potential mature height of tree

+ 12.5m+ 

# 7.5m+ 

* 4.5m+