CIVL 395 Environmental Impact Assessment [3] Housing Development in Tuen Mun Area 1 Proposed Bridge at Tuen Mun Are

1. CIVL 395 Environmental Impact Assessment [3] Housing Development in Tuen Mun Area 1 Proposed Bridge at Tuen Mun Area 18 HS Kan March 2007

2. Water Quality Impact Assessment Sewerage Impact Assessment

3. Water Pollution Control Ordinance Cap 358 (WPCO) • All kinds of wastewater, whether discharged into communal sewers, storm drains, river courses or waterbodies are subject to control, except • Domestic sewage discharge into sewers • Discharge of unpolluted water • All discharges subject to control shall be covered by an effluent discharge licence • Physical, chemical and microbial quality • Flow • Dependent upon • Location of discharge • Beneficial use of the receiving water • Pre-treatment as necessary

4. Technical Memorandum on EIA Process, EIAO Cap499 • Annex 6 • 4 aquatic componentsto be considered • Water quality • Hydrology • Bottom sediments • ecology • To achieveWater Quality Objectives under theWPCO • Aesthetic enjoyment • Sight, smell, taste, touch • Human health • Potable use, irrigation, bathing & recreational, contamination of seafood • Pathogenic indicators E. coli • Bioaccumulation, paralytic shellfish poisoning, etc • Aquatic life • Integrity and balance of the aquatic ecosystem • Natural properties of the waterbody – temp, salinity, DO, pH, turbidity, etc. • Nutrient input, accumulation of harmful substances • Physical environment of the waterbody – sedimentation, etc. • Industrial use • Prevention of deleterious chemicals, flotables, biological growths, etc. • Cooling water systems, shipping

5. Water Quality Impact Assessment • Description of the environment • Marine water, coastal water, river, etc • Identification of pollutant sources • Existing or planned • From the project itself and elsewhere, e.g. concurrent projects • Identification of water sensitive receivers • Beaches, water recreation areas, flushing water intakes, cooling water intakes, fish culture zones, marine parks, corals, mangroves, SSSI, etc. • Existing or planned • Baselining the environment • Existing water quality monitoring measurements, etc • Dedicated baseline surveys • Common parameters measured: • DO, turbidity, SS, BOD, Inorganic N, Ammonia N, chlorophyll-a, E. coli • Impact evaluation • Prediction of the transport of pollutants from the sources to the receivers • Oceanographic data • Flow tracking • Numerical modelling • Mitigation measures and monitoring

6. Baselining the Environment

7. Water Quality Modelling • Physical, chemical and biological processes • Hydrodynamic modelling • Coastline and bathymetry • Oceanographic and meteorological information • Non-steady flow and transport phenomena • Water quality modelling • Pollutant inventory • Advection-diffusion-reaction mechanisms • Physical process, e.g. • oxygen exchange with the atmosphere • sedimentation of suspended substances • Biochemical process, e.g. • nitrification • algal growth • decay • Boundary conditions, extent of model • Calibration and validation important

8. Water Quality Numerical Modelling – the Waterbody

9. Water Quality Numerical Modelling – the Waterbody

10. Water Quality Numerical Modelling – Output

11. Other Water Quality Assessment Criteria • Water quality for flushing water intake at sea • Colour < 20 Hazen units • Turbidity < 10 NTU • Suspended solids < 10 mg/l • Dissolved oxygen > 2 mg/l • Ammonium-N < 1 mg/l • BOD5 < 10 mg/l • Synthetic detergents < 5 mg/l • E. coli < 20,000/100 ml

12. Water Quality Impacts – Construction phase • Construction site runoff • Exposed soil surfaces • Oil from machineries, etc • Bentonite slurry, grout, etc from piling works • Sewage from workforce • Presence of sewers, chemical toilets • Accidental spillage of chemicals • Mitigation measures • Good housekeeping with regular tidying • Shielding of stockpiled materials • Intercepting channels • Silt traps • Oil separators • Reuse and proper disposal of bentonite • Protection of drainage facilities

13. Sewerage Impact Assessment • To safeguard public health • Additional flows & loads arising • Impacts on existing sewerage facilities • Sewers • Pumping stations • Sewage treatment works • Disposal facilities • Others e.g. dry weather flow interceptors • Proper pre-treatment, treatment and/or disposal of flows arising, at all stages of the project • DSD Sewerage Manual

14. ExistingSewers&Drains

15. Unit Flow Factors

16. Note: Peaking factor is applied globally.

17. Note: Peaking factor is applied globally.

18. Additional information in relation to SIA • Public housing estate at Site B • Housing type: Low-cost rental • No. of employees: 20 • Private housing • Housing type: R1 • No. of employees: 20 • Private housing club house • Restaurant with an average daily flow of 1000 m³/day • No. of employees: 35 • Primary school • No. of students: 700 • No. of employees: 80

19. 300 MH-A1 CL 21.80 X1 20.70 MH-A2 CL 18.70 A1 17.15 X1 17.10 MH-A3 CL 15.20 A1 13.10 X1 13.00 MH-B1 CL 16.50 X1 14.70 MH-B2 CL 16.40 A1 12.45 X1 12.40 MH-B3 CL 7.50 A1 5.20 X1 5.15 300 300 Existing Sewers 300 LEGEND CL Cover level (ground level) A Incoming sewer invert level X Outgoing sewer invert level 375

20. Some particular points to consider • Depth and alignment of new sewers • Connection to existing sewerage system • Need new pumping stations? • Any constraints due to the Light Rail Transit? • Trenchless methods • Minimum clearance requirements? • Impacts on the existing residents and other people during construction stage • Impacts on all residents and other people during the operation stage ASSUME: Capacity of existing sewerage is adequate.

21. Solid Waste

22. Solid Waste • Numerous ordinances and regulations • Waste Disposal Ordinance • Waste Disposal (Chemical Waste) (General) Regulations • Public Cleansing and Prevention of Nuisance Regulation under the Public Health and Municipal Services Ordinance • Provides control on illegal tipping of wastes on unauthorized sites • Website for ordinances and regulations: http://www.justice.gov.hk/Home.htm • Construction & Demolition (C&D) Materials • Accounts for some 40% of waste disposed of to landfills in 2003 • Insufficient landfill space • Over 80% of C&D materials is inert • Distinguishes between • Public fill – the inert portion • C&D waste – the non-inert portion • Material with more than 30% inert content need sorting before disposal to landfill • For projects generating50,000 m³or more C&D materials, the preparation of a C&D Material Management Plan

23. Solid Waste • Other wastes in construction stage • Used bentonite • General refuse • Contaminated soil/sediments • Assessment • EIAO-TM Annexes 7 and 15 • Estimate the types and quantities of wastes • Identify opportunities for waste reduction and beneficial use of the waste • Alternative design and alternative materials • Assess impacts associated with the handling and disposal of wastes

24. Solid Waste • Control and mitigation • Contaminated soil/sediments • EPD’s Guidance Notes for Investigation and Remediation of Contaminated Sites of Petrol Filling Stations, Boatyards, and Car Repair/Dismantling Workshops • Works Bureau Technical Circular No. 3/2000 on dredged sediment • C&D Materials • Waste Management Plan • Designated disposal sites • 3 strategic landfills: WENT, NENT, SENT • Trip-ticket system • Sorting of C&D materials • Use of recycled aggregates • Use of non-timber formwork and recyclable materials for temporary works • Charging scheme • Good housekeeping • Proper chemical waste handling procedures • Reduction, Recycle, Reuse