NWSS-M004 — Separation quality, container state and contamination
Provisional. Usable pending approval; a project-proposed concept only by the project that proposed it.
- Code: NWSS-M004
- Version: NWSS-2026-11-09
- Approval status: Provisional
Observation of the containers at sampled service points on scheduled evaluations (present, content state, condition and, for a container in use, the separation quality of its contents) and of sampled bags or containers opened in contamination audits (the streams found against the stream audited), with the rates over them: deployed containers present and usable, containers by separation quality and contaminated audit samples.
underlying principles and assumptions
Separation quality is the evaluator’s rating of one container’s contents against its stream on the five-level scale; only a container in use is rated (ADR-0005). An empty, misused or missing container is a container state, never a separation rating, and is counted under container retention. Rates rest on scheduled evaluations only; an unscheduled observation is kept and reported apart. Contamination is defined by the streams found in a sample, not by any project’s answer codes. An evaluator never evaluates service points on a round they collected (ADR-0004).
methods and procedures
On each scheduled evaluation, for every container deployed to the service point under its enrolment in force, record whether it is present, its content state, its condition, and for a container in use the separation quality of its contents, with a photograph. In a contamination audit, draw the sample of bags or containers of one stream the audit plan sets, open each, and record the streams whose material is found, with a photograph.
data requirements and inputs
Service point evaluation records fulfilling scheduled visits, with visit outcome, observer and observer role, and one container observation per deployed container: content state, condition and, where in use, separation quality; the deployments in force at the service point from NWSS-M002. Contamination audit records with one contamination observation per sample: audited stream and streams found; the facility and, where the sample is traceable, the collector. From the project design: the monitoring plan (sample size and visit window) and the audit plan’s sample size.
calculation and transformation rules
Let E be the evaluation records with visit outcome completed, dated in the reporting period, that fulfil a scheduled visit inside its visit window. (1) For each e in E at service point x, let K be the containers deployed to x under its enrolment in force on e’s date, the latest deployment per stream governing. Deployed containers present and usable = 100 × (containers in K observed with a content state other than container missing and a condition of very good, good, or damaged but functional) / |K|, a container in K with no observation counting as missing; counts by content state and condition are read on the axes. (2) Containers by separation quality = 100 × (ratings at level k of stream s) / (ratings of stream s), over container observations in E with content state in use; ratings on evaluations outside E are reported alongside. The headline share is clean plus minor contamination. (3) For each contamination observation o with audited stream a and streams found F, o is contaminated when F holds a stream other than a. Contaminated audit samples = 100 × (contaminated samples of stream a) / (samples of stream a) over audits dated in the period; an audit passes when none of its samples is contaminated, and the share of audits passed and the sample count are reported alongside.
outputs and units of measure
Deployed containers present and usable (PERCENT) by content state, condition and stream; containers by separation quality (PERCENT) by level and stream, with unscheduled ratings alongside; contaminated audit samples (PERCENT) by audited stream, facility and collector, with audits passed and samples alongside.
validation and verification approach
Validation: a reviewer with Knowledge and Skills Reputation in survey and monitoring design checks the monitoring plan’s sample and the audit plan. Verification of separation quality: a reviewer in source separation and behaviour change, who never collected on the rounds serving the sampled service points, checks a sample of ratings against their photographs and that no empty, misused or missing container carries a rating. Verification of contamination: a reviewer in waste characterisation and sampling, who did not audit the samples, checks audit photographs against the streams recorded.
limitations and applicability boundaries
Separation quality is a visual judgement on the day of the visit; consistency between evaluators depends on training and photographs. Rates describe the scheduled sample, not every service point, and inherit its design. A contamination audit records which streams are present, not their mass share, so it does not give a mass-based contamination rate. Load-level ratings a facility operator makes at weighing are not part of these indicators.
rationale
The weekly report folded a missing container into poor separation, dropped empty containers silently and reported some projects only, while the sorting audit was computed and never shown. Observing every deployed container, rating only those in use and defining contamination by the streams found separates container loss, household behaviour and facility-measured contamination into three checkable rates.
Indicators it serves
Activity types
- Contamination audit
- Service point evaluation
Knowledge domains a reviewer needs
- Source separation and behaviour change
- Survey and monitoring design
- Waste characterisation and sampling
Variables
| Variable | Role | Unit | Description |
|---|---|---|---|
| Containers by separation quality | DerivedOutput | PERCENT | 100 x ratings at level k of stream s / ratings of stream s, containers in use, scheduled evaluations. |
| Contaminated audit samples | DerivedOutput | PERCENT | 100 x samples of stream a with any other stream found / samples of stream a. |
| Deployed containers present and usable | DerivedOutput | PERCENT | 100 x deployed containers observed present and usable / deployed containers on completed scheduled evaluations. |
| Audited stream (a) | MeasuredInput | UNITLESS | The stream an audit sample was presented as. |
| Collector (k) | MeasuredInput | UNITLESS | The agent in the collector role named on a record, resolved from the collector tag at observedAt under the scan resolution rule of ADR-0003. |
| Container condition | MeasuredInput | UNITLESS | Very good, good, damaged but functional or unusable. |
| Container content state | MeasuredInput | UNITLESS | In use, empty, used for another purpose or missing. |
| Deployed container | MeasuredInput | UNITLESS | A container a deployment placed at the service point. |
| Facility (f) | MeasuredInput | UNITLESS | The facility a record was made at. |
| Observed at (t) | MeasuredInput | UNITLESS | The instant the observation or record was made; its local date in the project’s time zone is the record’s date. |
| Restated record | MeasuredInput | UNITLESS | The earlier record a record replaces; of a record and its restatements only the latest counts (ADR-0006). |
| Scheduled visit cancelled | MeasuredInput | UNITLESS | A scheduled visit cancelled with no replacement; it is no longer due. |
| Scheduled visit fulfilled | MeasuredInput | UNITLESS | The scheduled visit an evaluation record answers; absent for an unscheduled observation. |
| Scheduled visit superseded | MeasuredInput | UNITLESS | The earlier scheduled visit a reissued one replaces; the superseded visit is no longer due. |
| Separation quality rating | MeasuredInput | UNITLESS | The rating of a container in use against its stream. |
| Service point (x) | MeasuredInput | UNITLESS | The service point a record or observation is about. |
| Streams found (F) | MeasuredInput | UNITLESS | Streams whose material was found in an audit sample. |
| Visit outcome recorded | MeasuredInput | UNITLESS | Completed, no respondent or wrong service point. |
| Withdrawn record | MeasuredInput | UNITLESS | The record a withdrawal declares never happened; a withdrawn record never counts (ADR-0006). |
Monitoring requirements
- Evaluations follow the monitoring plan: Evaluation rates use only records fulfilling a scheduled visit inside its window; scheduled visits are issued before their dates and never edited.