Rural Planning and Improvement Strategy - Minor Projects Environmental Guidance Note

Annex 1
Recommended Pollution Control Clauses for Construction Contracts

WATER POLLUTION CONTROL

 

2.1 Water pollution control - general requirements
2.1.1 The Contractor shall undertake environmental protection measures to reduce the environmental impacts arising from the execution of the Works. In particular, he shall arrange his method of working to minimise the effects on the air, noise, water quality as well as nuisance of waste within and outside the Site, on transport routes and at the loading, dredging and dumping areas.
   
2.1.2 The Contractor shall provide a temporary stormwater drainage system along the periphery and within the site area in order to prevent surrounding stream courses or water bodies from contamination by site run-off. The stormwater drainage system shall include silt traps and grease traps as appropriate and the design of such system shall be submitted to the Engineer. Who shall have the discretion to agree/approve the Contractor's proposed drainage system prior to construction.
   
2.1.3 Exposed slopes and stockpiles shall be protected from storms to prevent contamination by site runoff.
   
2.1.4 Silt and grease removal facilities shall be maintained and cleaned at least once per week and after each rainstorm or as deemed necessary by the Engineer.
   
2.2 Marine Plant and Equipment
2.2.1 The marine plant and equipment to be used on the Works shall meet the requirement in Clauses 2.3.1 and 2.3.3 and shall be operated to achieve the water quality requirements. The Contractor shall provide all necessary facilities to the Engineer for inspecting or checking such plant and equipment and shall not use such plant and equipment for the execution of the Works without the agreement of the Engineer. The Engineer may require the Contractor to carry out trials of any plant and equipment to prove their suitability.
   
2.2.2 After commencement of the Works, if the plant and equipment or work methods are in the opinion of the Engineer causing unacceptable adverse impacts which can be checked against the Technical Memorandum on Effluent Standards issued under the Water Pollution Control Ordinance, then the Engineer may notify the Contractor in writing and the Contractor shall immediately initiate remedial measures so as to halt such deterioration. If the Contractor fails to initiate remedial measures, the Engineer may stop the Works. Where such remedial measures include the use of additional or alternative plant and equipment such plant and equipment shall not be used on the Works until agreed by the Engineer. Where remedial measures include maintenance or modification of previously approved plant and equipment, such plant and equipment shall not be used on the Works until such maintenance or modification is completed and the adequacy of the maintenance or modification is demonstrated to the satisfaction of the Engineer.
   
2.2.3 The Contractor shall comply with the conditions of dumping permits obtained from the Director of Environmental Protection. The permits shall be prominently displayed in the Chinese and English language on site and also on the dredgers and barges.
   
2.3 Avoidance of pollution during dredging, transporting and dumping of marine mud
2.3.1 Pollution avoidance measures shall include but not be limited to the following :
  1. all equipment shall be designed and maintained to minimise the risk of silt and other contaminants being released into the water column or deposited in locations other than designated location;
  2. mechanical grabs shall be designed and maintained to avoid spillage and shall seal tightly while being lifted;
  3. where trailing suction hopper dredgers for dredging of marine mud are in use, overflow from the dredger and the operation of lean mixture overboard systems shall not be permitted unless expressly approved by the Engineer in consultation with the Director of Environmental Protection;
  4. cutterheads of suction dredgers shall be suitable for the material being excavated and shall be designed to minimise overbreak and sedimentation around the cutter;
  5. all vessels shall be sized such that adequate clearance is maintained between vessels and the sea bed at all states of the tide to ensure that undue turbidity is not generated by turbulence from vessel movement or propeller wash;
  6. all pipe leakages shall be repaired promptly and plant shall not be operated with leaking pipes and all pipe leakages shall be repaired promptly;
  7. before moving the vessels which are used for transporting dredged materials excess material shall be cleaned from the decks and exposed fittings of vessels and the excess materials shall never be dumped into the sea except at the approved locations;
  8. adequate freeboard shall be maintained on barges to ensure that decks are not washed by wave action;
  9. the Contractor shall monitor all vessels transporting material to ensure that no dumping outside the approved location takes place. The Contractor shall keep and produce logs and other records to demonstrate compliance and that journey times are consistent with designated locations and copies of such records shall be submitted to the Engineer;
  10. all bottom dumping vessels shall be fitted with tight fitting seals to their bottom openings to prevent leakage of material;
  11. loading of barges and hoppers shall be controlled to prevent splashing of dredged material to the surrounding water, and vessels shall not be filled to a level which will cause overflowing of material or polluted water during loading or transportation; and
  12. the Engineer may monitor any or all vessels transporting material to check that no dumping outside the approved location nor loss of material during transportation takes place. The Contractor shall provide all reasonable assistance to the Engineer for this purpose.
   
2.3.2 The Contractor shall be responsible for obtaining all necessary dumping permits as stipulated in the Works Branch Technical Circular No. 22/92 "Marine Disposal of Dredged Mud." The dredged marine mud shall be deposed of at a disposal site as designated in the dumping permit.
   
2.3.3 When dredging, transporting and disposing of contaminated marine mud, the Contractor shall implement adequate measures for the avoidance of pollution which shall include but not be limited to the following :
  1. dredging of contaminated marine mud shall be undertaken by a suitable grab dredger using closed watertight grab;
  2. transport of contaminated marine mud shall be by split barge of not less than 750 m3 capacity, well maintained and capable of rapid opening and discharge at the disposal site;
  3. the material shall be placed into the disposal pit by bottom dumping;
  4. discharge from split barges shall take place within a radius of 100 metres of centre of the area allocated for the disposal of contaminated marine mud;
  5. discharge shall be undertaken rapidly and the hoppers shall then immediately be closed, material adhering to the sides of the hopper shall not be washed out of the hopper and the hopper shall remain closed until the barge next returns to the disposal site; and
  6. the dumping vessel shall be anchored throughout the dumping operation.
   
2.3.4 The Contractor shall ensure that all marine mud is disposed of at the approved locations. He shall be required to ensure accurate positioning of vessels before discharge and shall be required to submit proposals for accurate position control at disposal sites to the Engineer for approval before commencing dredging and dumping.
   
2.3.5 The Contractor shall ensure that all unsuitable material is disposed of at the approved landfill or other designated location.
   
2.3.6 The Contractor shall only employ vessels equipped with automatic self-monitoring devices as specified by the Director of Environmental Protection for disposal operation, and shall co-operate with and facilitate the Director of Environmental Protection to inspect the device and retrieve the record stored in the device on a regular basis.
   
2.3.7 The Contractor shall provide experienced full time personnel on board all dumping vessels to ensure that appropriate methods to minimise pollution are implemented.
2.4 Protection of Water Quality at Water Intakes
2.4.1 When dredging mud or placing fill in the vicinity of water intakes, the Contractor shall protect the water intake by surrounding it with a suitable silt screen to prevent excessive suspended solids from entering the intake. The silt screen shall be designed to ensure that the concentration of suspended solids entering the intake meets intake user requirements..
   
2.5 Silt Curtains
2.5.1 If silt curtains shall be used to contain sediment losses during dredging the Contractor shall be responsible for designing, agreeing with the Engineer and installing silt curtains, where required, to minimize the impacts on the water quality and the protection of water quality at water intakes as described in Clause 2.4.1.
   
2.5.2 Silt curtains shall be formed from tough, abrasion resistant, permeable membranes, suitable for the purpose, supported on floating booms in such a way as to ensure that the ingress of turbid waters to the enclosed waters shall be restricted.
   
2.5.3 The bottom of the curtain shall be formed and installed in such a way that tidal rise and fall are accommodated, and that the ingress of turbid waters is limited. The removal and reinstallation of such curtains during typhoon conditions shall be as agreed with the Director of Marine.
   
2.5.4 The Contractor shall regularly inspect the silt curtains and check that they are moored and marked to avoid danger to marine traffic. Any damage to the silt curtain shall be repaired by the Contractor promptly and the works shall be stopped until the repair is effected to the satisfaction of the Engineer.
   
2.6 Refuse containment booms and floating refuse
2.6.1 The Contractor shall provide and install refuse containment booms before commencing public dumping to confine the floating debris arising within the site as a result of public dumping. Details of the refuse containment booms shall be submitted to the Engineer for approval before their use on site.
   
2.6.2 It is expected that public dump material may contain refuse, timber debris, or oil contamination and these shall be removed by the Contractor. The Contractor shall segregate all inert construction waste material suitable for reclamations. All non-inert construction waste material shall be disposed of at a public landfill.
   
2.6.3 Plastic buoys for the refuse booms will be provided by the Employer. The plastic buoys shall be collected from and returned to the Civil Engineering Department Technical Services Division's Store at North Point after use and cleaning.
   
2.6.4 The Contractor shall provide adequate sinker blocks and lit marker buoys to ensure that the booms are visible above the water line and securely anchored. The lights on the marker buoys shall be quick flashing yellow light visible all round the horizon at a distance of at least 2 km and details shall be submitted to the Engineer for approval. The maximum spacing between the flashing yellow light shall be 30 metres. The Contractor shall properly maintain and operate the booms to the satisfaction of the Engineer throughout the progress of public dumping of the Site and shall replace the same if necessary when they are under repair or beyond repair.
   
2.6.5 The Contractor shall deploy sufficient sampans and labour for collecting floating refuse and preventing floating refuse within the Site from drifting into public waters. The frequency of collecting floating refuse shall be as agreed by the Engineer. Floating refuse collected shall be disposed of off Site by the Contractor.
   
2.6.6 The Contractor shall make due allowance in programming the public dumping for the provision, installation, operation and maintenance of the refuse booms and the regular collection of the floating refuse throughout the progress of the reclamation work.
   
2.6.7 The Contractor's attention is drawn to the SCC Clause No. (      ) on the Employer's power to carry out the work by person other than the Contractor if the Contractor shall fail to carry out any work required under this PS Clause.
   
2.7 Discharge into sewers and drains
2.7.1 The Contractor shall not discharge directly or indirectly or cause or permit or suffer to be discharged into any public sewer, stormwater drain, channel, stream-course or sea any trade effluent or foul or contaminated water or cooling or hot water without the prior written consent of the Engineer in consultation with the Director of Environmental Protection and Director of Water Supplies, who may as a condition of granting his consent require the Contractor to provide, operate and maintain at the Contractor's own expense to the satisfaction of the Engineer suitable works for the treatment and disposal of such trade effluent or foul or contaminated or cooling or hot water. [The design of such treatment works shall be submitted to the Engineer for approval not less than one month before the commencement of the relevant works.]
   
2.7.2 If any office, site canteen or toilet facilities is erected, foul water effluent shall be directed to a foul sewer or to a sewage treatment and disposal facility either directly or indirectly by means of pumping or other means approved by the Engineer.

 

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