18-Env-B6 Agricultural Waste Management · December 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams, December 2016 — 04-Env-B6, Agricultural Waste Management (3 hours, open book, all questions to be attempted, 100 marks total).
Reference texts: Rynk et al., On-Farm Composting Handbook (NRAES-54); OMAFRA, Nutrient Management Act, 2002 and O. Reg. 267/03 / Nutrient Management Protocol (NMAN); Metcalf & Eddy, Wastewater Engineering (anaerobic digestion chapter); ASABE Standards (manure storage, land application equipment).
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.
A liquid manure storage is a structure holding a large, corrosive, potentially environmentally-harmful liquid load, and professional engineering involvement is warranted at several stages. Geotechnical investigation establishes bearing capacity, groundwater table depth and soil permeability at the site, which governs whether an earthen storage can be built without a synthetic/clay liner and how far the structure must be set back from wells and watercourses. Structural design must account for hydrostatic pressure from the stored liquid, lateral earth pressure, seismic and wind loads (for above-ground tanks), frost action, and ice loading on walls — concrete or steel tank walls and earthen embankment storages both need a documented design against these loads. Seepage/leak-prevention design (liner selection, leak-detection systems where required) protects groundwater, and Ontario's Nutrient Management Act requires an engineer's design and sign-off for storages above a size threshold specifically for this reason. Freeboard and emergency overflow provisions must be sized for the design storm plus operational freeboard so the storage cannot overflow uncontrolled. Finally, construction inspection and as-built certification by the engineer of record confirms the structure was built as designed (liner integrity, reinforcement placement, compaction) before it is put into service, and this certification is typically a regulatory submission requirement, not merely good practice.
