Review the evidence signals before interviewing. Then use the anchored descriptions—not instinct alone—to choose the score that best matches each answer.
01
Evaluation factor
Technical depth
35% weight
Check command of water chemistry: Langelier and Ryznar indices, RO membrane fouling versus scaling, chlorine dioxide dosing, ion exchange regeneration, and ASHRAE 188 or L8 legionella requirements.
Evidence to listen for
Explains the physics or mechanism behind their work, not just the tooling
Names the standards, tolerances, and constraints they designed against
Can defend a design decision under follow-up questions
Distinguishes what they personally engineered from what the team delivered
Five-point scoring guide
1
Poor
Cannot explain the fundamentals of their own stated specialism.
2
Needs Improvement
Knows the vocabulary but not the underlying mechanism; struggles under follow-ups.
3
Satisfactory
Solid working knowledge for the role; depth thins out on edge cases.
4
Very Good
Strong command of the domain; explains trade-offs and defends decisions well.
5
Excellent
Explains cycles of concentration, silt density index limits and inhibitor selection with numbers, not vendor slogans or generic chemistry.
02
Evaluation factor
Work that shipped
30% weight
Ask for commissioned systems: RO or ultrafiltration skids, cooling tower programmes, ZLD or effluent plants, with capacity, recovery rate and chemical cost per cubic metre delivered.
Evidence to listen for
Names specific programmes, parts, or systems that reached production or field use
States their own scope inside the project
Can give measured outcomes: yield, cycle time, cost, failure rate
Explains what went wrong and what they changed
Five-point scoring guide
1
Poor
No delivered work; experience is coursework, lab-only, or purely observational.
2
Needs Improvement
Contributed to projects but cannot say what shipped or what their part was.
3
Satisfactory
Has delivered real work; outcomes described without numbers.
4
Very Good
Names shipped work and their scope, with some measured results.
5
Excellent
Names specific plants and quantified outcomes: recovery lifted, blowdown cut, membrane life extended, discharge consents met.
03
Evaluation factor
Diagnosis under uncertainty
20% weight
Probe how they traced a problem: sudden conductivity spike, boiler carryover, microbial counts breaching limits, or differential pressure climb across a membrane train.
Evidence to listen for
Describes a real failure they chased to root cause
Shows a method: isolate variables, reproduce, measure, eliminate
Distinguishes correlation from cause
Says what they ruled out and why, not only what the answer turned out to be
Five-point scoring guide
1
Poor
No diagnostic method; guesses or escalates immediately.
2
Needs Improvement
Trial and error with no structure; cannot explain how they narrowed the cause.
3
Satisfactory
Reasonable method on familiar problems; less structured on novel ones.
4
Very Good
Clear systematic approach with a real root-cause story.
5
Excellent
Walks through sampling, jar tests, autopsy of a fouled element and data trending before naming a root cause.
04
Evaluation factor
Working across the org
15% weight
Assess dealings with plant operators, EHS teams, chemical suppliers and regulators during audits, water risk assessments or discharge permit renewals.
Evidence to listen for
Explains technical constraints to non-technical stakeholders without condescension
Has negotiated scope, cost, or timeline with manufacturing, product, or suppliers
Documents decisions so others can act on them
Takes review feedback without defensiveness
Five-point scoring guide
1
Poor
Cannot communicate outside their specialism; dismissive of other functions.
2
Needs Improvement
Communication gaps cause rework; avoids stakeholder contact.
3
Satisfactory
Works adequately with other teams; documentation is thin.
4
Very Good
Communicates clearly across functions; reliable collaborator.
5
Excellent
Describes training operators on dosing logs and negotiating corrective actions with site management and inspectors without escalation.
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