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18-Env-A6 Solid Waste Engineering and Management · May 2017

Question 10 of 16: Issues in Implementing a Composting Facility

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

National Examination, May 2017 — 04-Env-A6 / 18-Env-A6, Solid Waste Engineering and Management. 3 hours duration, closed book, non-communicating calculator permitted. All 16 questions constitute a complete paper (100 marks total).

Reference texts: Tchobanoglous, Theisen & Vigil, Integrated Solid Waste Management: Engineering Principles and Management Issues; Vesilind, Worrell & Reinhart, Solid Waste Engineering; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); CCME, Guidance Document on Landfill Gas Management; ISO 14040/14044, Environmental Management — Life Cycle Assessment.

Q6 below is solved from the six printed per-component rows, which are unambiguous exam-given data — see the callout at Q6 for the arithmetic. Table 2's "5.800 kJ/kg" organics value (period instead of comma) is read as 5,800 kJ/kg.

Question 10: Issues in Implementing a Composting Facility (4 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(1) Site selection and permitting — an adequate buffer distance from neighbouring residences (odour and noise), suitable drainage/impervious pad to contain leachate/runoff, and provincial environmental approval. (2) Odour control — the single most common cause of composting-facility complaints and closures; requires proper aeration/turning to keep the pile aerobic, biofilters or covered/enclosed (in-vessel) systems for more sensitive sites. (3) Feedstock quality control and contamination — non-compostable contaminants (plastic bags, glass) in the incoming organics stream degrade finished-compost quality and marketability, requiring either strict source-separation enforcement or a screening/de-bagging step. (4) Market for the finished product — a composting facility only functions as a diversion solution if there is a reliable off-take market (agriculture, landscaping, topsoil blending) for the compost produced; without one, finished compost simply becomes a new waste-disposal problem.

These four issues interact in ways that make sequencing important: siting and permitting (1) effectively bound what odour-control technology (2) is affordable or required — an enclosed in-vessel system may be mandated at a tighter-buffer site but unnecessary at a well-buffered rural one — while feedstock quality control (3) directly determines whether the finished product can find and hold a market (4), since contaminated compost is difficult to sell regardless of how well the facility itself is sited or odour-managed. A municipality evaluating a composting facility proposal should assess these four together, not sequentially, since a technically sound facility that fails on any single one of them (most often market access) does not deliver a durable diversion outcome. A feasibility study should therefore score all four together before committing capital.