HKIE Professional Assessment - Environmental Discipline cheat sheet

Air dispersion modelling: Gaussian plume equation C(x,y,z) = Q/(2πuσyσz)·exp(-y²/2σy²)·[exp(-(z-H)²/2σz²)+exp(-(z+H)²/2σz²)]; Pasquill-Gifford stability classes A (most unstable) to F (most stable) set σy and σz.

Noise: sound pressure level Lp = 20·log10(p/p0), p0 = 20 µPa; sound power level Lw = 10·log10(W/W0), W0 = 1 pW. Point source in free field: Lp = Lw − 20·log10(r) − 11 dB.

Multiple incoherent sources combine logarithmically: Ltotal = 10·log10(Σ10^(Li/10)); doubling of source count or equal sources adds 3 dB, ten equal sources add 10 dB.

Wastewater: BOD5 is oxygen demand over 5 days at 20 °C with nitrification suppressed; typical k (base e) ≈ 0.23 /day for domestic sewage; ultimate BOD L0 = BOD5/(1−e^(−5k)).

Activated sludge design: solids retention time SRT = V·X/(Qw·Xr + Qe·Xe); F/M = Q·S0/(V·X); sludge yield Yobs = Y/(1+kd·SRT). Typical domestic SRT 10-25 days; nitrification needs SRT above the nitrifier minimum (temperature dependent).

Water treatment: sedimentation overflow rate v0 = Q/A (m³/m²·d); Stokes' law settling velocity vs = g(ρp−ρw)d²/(18µ); filtration rate expressed as m³/m²·h (m/h).

Drinking water disinfection: CT value = disinfectant residual concentration (mg/L) × contact time (min); required CT depends on disinfectant, temperature, pH and log inactivation credit.

Solid waste and landfill: waste density, compaction ratio, and landfill gas generation via first-order decay; leachate generation estimated by water balance (precipitation − evapotranspiration − runoff − storage).

Environmental chemistry: Henry's law p = H·x (or C_air = H'·C_water); pH and alkalinity govern ammonia speciation (NH3/NH4+, pKa ≈ 9.25 at 25 °C) and metal solubility.

Mass balance first: accumulation = inputs − outputs ± reactions; apply to a defined control volume (reactor, building, catchment) and state assumptions (steady state, complete mixing, first-order kinetics).

Reactor models: CSTR steady-state C/C0 = 1/(1+kτ); plug flow C/C0 = exp(−kτ); hydraulic retention time τ = V/Q. Compare with tracer test results before selecting a model.

Design flows: use peaking factors on dry weather flow (typical diurnal peak 1.5-3× average for sewage; storm flow via rational method Q = C·i·A with i in mm/h and A in hectares giving L/s by Q = 2.78·C·i·A).

Unit conversions to check: 1 m³ = 1000 L; 1 mg/L = 1 g/m³; 1 ppm ≈ 1 mg/L in water; 1 bar = 100 kPa ≈ 10.2 m water head; power P = ρgQH/η.

Sensitivity and uncertainty: identify dominant parameter, run best/worst case, and state the design margin explicitly rather than hiding it in a single number.

Compliance check: compare predicted concentrations with the applicable standard (e.g. Hong Kong Air Quality Objectives, Technical Memorandum effluent standards) and show the margin as a percentage.

Energy and carbon: specific energy (kWh/m³ for pumping/aeration), and carbon footprint = activity × emission factor; verify units (kg CO2-e per unit).

Verification: cross-check a model output against a hand calculation or a second method (e.g. compare a dispersion model with a screening nomograph) before issuing a design.

Core duties: competence only within your field, honesty in reports, full and frank disclosure of known risks, and no misrepresentation of qualifications or results.

Conflict of interest: declare any financial or personal interest in a project or supplier to the client and employer in writing, and withdraw from decisions where the interest could bias judgement.

Confidentiality: client information is confidential; disclosure is permitted only with consent, where legally required, or where public safety is at risk.

Bribery and facilitation payments: HKIE and ICAC expectations prohibit offering or accepting advantages for professional decisions; record and report any request.

Environmental duty: identify and communicate environmental impacts and legal obligations (e.g. Environmental Impact Assessment Ordinance, Water Pollution Control Ordinance, Air Pollution Control Ordinance) to the client.

Whistleblowing: if an employer persists in unsafe or unlawful practice, escalate internally first, then to the relevant authority; document the steps taken.

Signing and sealing: only sign work you have personally directed or reviewed; keep records and calculations for the period required by the client and statute.

Public statements: technical opinions given publicly must be objective, within your competence, and distinguished from personal views; correct errors promptly.

HKIE training scheme: structured Scheme A training typically 2 years under an approved supervisor with periodic progress reports and a logbook of experience.

Competence development cycle: plan (identify gaps against the competence framework) → do (project experience) → review (supervisor feedback) → record (logbook evidence).

Evidence quality: record what you did, the decisions you made, the constraints, and the outcome - a claim without evidence is not assessable.

Professional judgement: state the problem, list options, evaluate against safety, environment, cost, programme and regulation, then justify the chosen option and record residual risk.

Ethical decision test: is it legal, is it safe, would I be comfortable if it were published, and have I declared any interest?

Mentoring and supervision: a supervisor must be competent in the field, available for review, and must not sign off work they have not examined.

Continuing professional development: maintain a CPD record (hours, activity type, relevance) and reflect on how each activity changed your practice.

Boundary of competence: when a task exceeds your experience, seek specialist input, state the limitation, and do not present another's work as your own.

Impact assessment sequence: baseline → predict impact → evaluate significance (magnitude × sensitivity) → mitigation hierarchy (avoid, minimise, restore, offset) → residual impact and monitoring.

Mitigation hierarchy is applied in order; offsets are the last resort and must be measurable, additional and long-term.

Monitoring plan design: define parameters, locations, frequency, method (with standard reference), detection limits, and the action/trigger level that prompts a response.

Stakeholder and statutory consultation: identify affected parties early, document consultation, and show how comments changed the design.

Construction phase controls: noise barriers/enclosures, dust suppression by watering, silt curtains and site drainage, and waste management plans; verify with site inspection records.

Emergency and spill response: containment first, then recovery, then disposal with consignment records; report to the authority within the statutory timeframe.

Life-cycle thinking: compare options on whole-life cost and environmental load (energy, water, waste, emissions), not just capital cost.

Audit and verification: check records against actual practice, sample rather than assume, and close out findings with named owners and dates.

Assessment structure: a training record and logbook review, a written submission, and an interview covering discipline knowledge, judgement and professional conduct.

Answer structure for interview: situation → what you analysed → options considered → decision and reason → outcome and lesson learned.

Quantitative answers: show the formula, substitute with units, state the result with units, and sanity-check the magnitude before commenting.

Know your own project numbers: design flows, loads, concentrations, standards applied, and the margin achieved - vague answers weaken credibility.

Regulatory awareness: be able to name the relevant Hong Kong ordinances and the authority responsible for each, and the role of the EIA process.

Ethics questions: identify the duty owed (public, client, employer, profession), declare interests, and state the action you would take and to whom you would report.

Common failure modes: claiming work not personally done, ignoring safety or environment in trade-off discussions, and being unable to justify a design value.

Reflective practice: prepare two or three examples of mistakes or near-misses and what changed in your practice as a result.