Earthwork management in canals: The extra excavated earth is commonly utilized to provide spoil banks on which side(s) of the canal alignment?

Introduction / Context:
Canal excavation generates large volumes of surplus earth. Efficient use of this material reduces hauling costs and enhances canal safety. A common practice is to form spoil banks (bunds) adjacent to the canal to protect against external drainage inflows and to provide access and containment.

Given Data / Assumptions:

• Standard irrigation canal in alluvial terrain.
• Surplus earth beyond that needed for forming canal banks.
• Local design may specify distances/setbacks for spoil banks.

Concept / Approach:
Depending on terrain and drainage patterns, spoil banks can be placed on one or both sides. In many projects, forming spoil banks on both sides ensures protection from external runoff, offers maintenance access, and minimizes breaches from overtopping by adjacent flood flows.

Step-by-Step Solution:
1) Identify surplus earth volumes from excavation quantities.2) Locate spoil banks suitably on one or both sides to avoid blocking natural drains.3) Provide cross-drainage or gaps where necessary to prevent ponding outside the canal.

Verification / Alternative check:
Standard practice notes and design manuals allow flexibility—placement on both sides is common, subject to hydrological constraints and right-of-way availability.

Why Other Options Are Wrong:

• Left-only or right-only: too restrictive; site conditions usually determine side(s).
• Removal from site: uneconomical unless mandated; material is usually reused locally.
• Only downstream of regulators: unrelated to where surplus earth should be placed.

Common Pitfalls:

• Blocking natural drainage with continuous spoil banks without culverts or gaps.
• Placing spoil too close to canal leading to slides into the prism.

Final Answer:
Both sides of the canal alignment as required.