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CIVL 395 Environmental Impact Assessment [3] Housing Development in Tuen Mun Area 1 Proposed Bridge at Tuen Mun Are PowerPoint Presentation
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CIVL 395 Environmental Impact Assessment [3] Housing Development in Tuen Mun Area 1 Proposed Bridge at Tuen Mun Area 18. HS Kan March 2007. Water Quality Impact Assessment Sewerage Impact Assessment. Water Pollution Control Ordinance Cap 358 (WPCO).

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slide1

CIVL 395 Environmental Impact Assessment [3] Housing Development in Tuen Mun Area 1 Proposed Bridge at Tuen Mun Area 18

HS Kan

March 2007

water quality impact assessment sewerage impact assessment
Water Quality Impact Assessment

Sewerage Impact Assessment

water pollution control ordinance cap 358 wpco
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
technical memorandum on eia process eiao cap499
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
water quality impact assessment
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
water quality modelling
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
other water quality assessment criteria
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
water quality impacts construction phase
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
sewerage impact assessment
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
additional information in relation to sia
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
slide19

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

some particular points to consider
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.

solid waste
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
solid waste23
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
solid waste24
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