| Annex A | B | C | D | E | F | G |

Mitigation Measures Extracted From Section 8.2.5, 8.2.6 and 8.2.7 of the EIA report.
(Relevant Section of the EIA report shall be referred to for assumptions for and details and the context of the mitigation measures)

To reduce noise impact

1. Bored piling shall be used for the pumping station and bridges for the Project, if the Project requires piling foundation.

2. Dredging operations will be carried out in the ponds to ensure that contaminated sediments are not inadvertently allowed into the new drainage channel. As the ponds are quite small and not very deep, it has been proposed that a single grab dredger be used for the operation.

3. The first level mitigation for construction activities is the use of quiet equipment. There are specific Powered Mechanical Equipment (PME) with sound power lower than those specified in Technical Memorandum on Noise from Construction other than Percussive Piling (TM1). Examples of such silenced PME known to exist are given below:

   Bulldozer: 110 dB(A) max;

   Breaker (hand): 110 dB(A) max;

   Bored Piling Rig: 110 dB(A) max;

   Dump Truck: 110 dB(A) max;

   Excavator: 105 dB(A) max;

   Lorry: 105 dB(A) max;

   Concrete Pumps: 105 dB(A) max;

   Compressors: 100 dB(A) max;

   Generators: 100 dB(A) max;

   Water Pumps: 88 dB(A) max;

   Poker Vibrator: 110 dB(A) max; and

   Loader: 105 dB(A) max.

4. The second level mitigation activities is the use of permanent or movable noise barriers of 3.5 to 4 metres high in addition to the use of quiet equipment. It should be noted that a barrier with sufficient height but insufficient length will significantly reduce its noise attenuation effectiveness. This is avoidable by arranging the barriers to encircle the noise source.

5. If further noise reduction is required, the following on-site measures should be considered

   use of noise enclosures;
   reduction in the number of noisy plant operating simultaneously;
   maintenance of noisy equipment so as to minimise noise;
   siting mobile plant away from NSRs;
   turning off noisy plant when not in use; and
   effective use of material stock piles and other structures for noise screening on-site.

   The contractors may also consider to use alternative working methods which are quieter than those assumed in this noise assessment.

6. For the main construction activities, the measures listed in Table 1 below should be adopted:

Table 1 Recommended Mitigation Measures by Activity for the Project

It should be noted that these mitigation measures are applicable primarily to following locations:

Phase 1

• Shek Wu Tong;
• Ko Po San Tsuen;
• Ko Po San Tsuen School;
• Kat Hing Wai;
• Ng Ka Tsuen;
• Tsz Tong Tsuen;
• Tin Sam Tsuen;
• Tai Kek; and
• Yuen Kong San Tsuen.

Table 2 Distance to NSRs affected by the Project

Measures to Mitigate Environmental Impacts from Site Run-off

To mitigate the environmental impacts from site run-off, the following shall be implemented:

1. the boundaries of earthworks shall be marked and surrounded by dykes or embankments. Temporary ditches such as channels, earth bunds or sand bag barriers shall be provided to facilitate run-off discharge into stormwater drain, via a silt retention pond;

2. sediment traps and channels shall be cleaned and maintained on a regular basis. Daily inspections of these facilities is required;

3. perimeter channels shall be provided at the site boundaries to intercept storm run-off from off-site. These channels shall be constructed before site formation works and earthworks;

4. manholes shall be adequately covered or temporarily sealed;

5. material storage stockpiles shall be covered with tarpaulin or similar fabric to prevent material washing away;

6. exposed soil areas shall be minimised to reduce the potential for increased siltation and contamination of run-off; and

7. earthwork final surfaces shall be well compacted and subsequent permanent work should be performed immediately.

Measures to Mitigate Environmental Impacts from Wastewater due to Construction Activities

To mitigate the environmental impacts from site run-off and drainage, the following shall be implemented:

1. water used for water testing, boring, drilling works, concrete batching and precast concrete casting shall be recirculated and reused;

2. online standby sump pumps shall be provided to prevent wastewater overflow from any water recycling system;

3. wastewater from concrete batching and precast concrete casting shall be treated for pH adjustment and silt removed prior to discharge into stormwater drains;

4. washwater from wheel washing facilities shall have sand, silt or other materials removed before discharge into stormwater drains; the access road sections between site exits and the public roads shall be paved with backfall to prevent site run-off from entering the public roads; and

5. drainage of groundwater shall be discharged into stormwater drains after removal of silt.

Measures to Mitigate Noise Impact During Construction

To mitigate the noise impact from construction, the following shall be implemented:

1. quiet equipment shall be used at all times and all locations;

2. purpose built, permanent or moveable noise barriers shall not have openings or gaps, to ensure the required noise attenuation effect;

3. noise barriers shall be erected close to, but no further than 20 metres distant from, plant in operation; and

4. the noise mitigation measures submitted under condition 2.9 of this Permit shall be fully implemented.

Measures to Mitigate Noise During Excavation Works

To mitigate the noise impact from Excavation works, the following shall be implemented:

1. the excavation mitigation measures as detailed in Annex A, attached to this Permit shall be used at locations where the works are closer than 100 metres to the nearest noise sensitive receivers, but 180 metres for schools; and

2. 3 metre high purpose built, noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are at distances of between 60 and 100 metres from the works;

3. 3.5 metre high purpose built noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are generally closer than 60 metres to the works; and

4. no more than 3 pieces of Powered Mechanical Equipment (PME) shall operate simultaneously in any one area or location, where noise sensitive receivers are generally closer than 60 metres to the works.

Measures to Mitigate Noise Impact During Access Road Construction

To mitigate the noise impact from access road construction, the following shall be implemented:

1. the access road construction mitigation measures as detailed in Annex A, attached to this Permit shall be used at locations where the works are closer than 100 metres to the nearest noise sensitive receivers, but 180 metres for schools;

2. 3 metre high purpose built noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are at distances of between 60 and 100 metres from the works;

3. 4 metre high purpose built noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are generally closer than 60 metres to the works; and

4. no more than 2 pieces of Powered Mechanical Equipment (PME) shall operate simultaneously in any one work site or location, where noise sensitive receivers are generally closer than 60 metres to the works.

Measures to Mitigate Noise Impact During River Bed Construction

To mitigate the noise impact from river bed construction, the following shall be implemented:

1. the river bed road construction mitigation measures as described in Annex A, attached to this Permit shall be used at locations where the works are closer than 100 metres to the nearest noise sensitive receivers, but 180 metres for schools;

2. 3 metre high purpose built noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are at distances of between 60 and 100 metres from the works;

3. 3.5 metre high purpose built noise barriers shall be erected between the plant in operation and nearby noise sensitive receivers, where noise sensitive receivers are generally closer than 60 metres to the works; and

4. no more than 3 pieces of Powered Mechanical Equipment (PME) shall operate simultaneously in any one work site or location, where noise sensitive receivers are generally closer than 60 metres to the works.

[ Back to First Page ]