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

Question 13 of 18: Determining Solid Waste Generation Rates and Composition

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

Notes on this paper

National Examination, December 2017 — 04-Env-A6 / 18-Env-A6, Solid Waste Engineering and Management. 3 hours duration, closed book, one of two calculators permitted (Casio or Sharp approved model). All eighteen (18) 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.); Freeze & Cherry, Groundwater; CCME, Guidance Document on Landfill Gas Management; Canadian Environmental Protection Act, 1999.

Question 13: Determining Solid Waste Generation Rates and Composition (8 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.

Part (a) — 13.1 Methodology. Establish a statistically representative sampling program stratified by generator category (residential single-family, residential multi-family, commercial, institutional, industrial) since composition and rate differ substantially between them. Use a recognized sorting protocol (in the spirit of ASTM D5231, Standard Test Method for Determination of the Composition of Unprocessed Municipal Solid Waste) — collect and weigh loads at the scale house or a dedicated sampling location, physically sort a representative sub-sample into standard component categories (paper, plastics, metals, glass, organics/food, yard waste, etc.), and weigh each fraction. Repeat sampling across multiple representative days to build a statistically sound average and range, and record total tonnage by route/generator category from routine collection-vehicle weighing to establish generation rates (kg/capita·day or kg/business·day) independent of the composition sub-sampling.

Part (b) — 13.2 Estimating seasonal effect without time to measure it. With only 30 days available, a direct year-round measurement program is not possible, so the seasonal adjustment is estimated indirectly: draw on published seasonal generation/composition factors from comparable communities of similar size, climate and demographic profile (e.g. elevated yard-waste generation in spring/fall, holiday-season peaks in December, summer increases in beverage-container and food-service waste), and apply a seasonal correction factor to the 30-day measured average rather than assuming that average is representative of the whole year. Cross-checking against the receiving landfill's or collection contractor's historical monthly tonnage records (if available) provides an additional, community-specific check on the assumed seasonal pattern.