Handling grit chamber output: Which use is NOT appropriate for grit and silt removed from grit chambers?

Introduction / Context:
Grit chambers remove heavy inorganic particles (sand, gravel, silt) to protect downstream processes. Proper disposal or reuse must avoid structural risks and health hazards. This question asks which proposed use is unsuitable.

Given Data / Assumptions:

• Material is mostly inorganic grit with possible organic contamination.
• No specialized washing or sanitization assumed.
• Reuse must not compromise structural integrity or hygiene.

Concept / Approach:

Concreting requires controlled aggregates meeting grading, cleanliness, durability, and strength requirements. Grit chamber outputs are neither graded nor clean enough and may introduce deleterious substances, compromising concrete performance. Conversely, regulated dumping to fill low-lying areas (with proper environmental controls) can be acceptable.

Step-by-Step Solution:

Verification / Alternative check:

Concrete codes disallow dirty, organic-laden, or weak aggregates. Many utilities dispose grit at approved landfills or use it for non-structural fill under environmental safeguards.

Why Other Options Are Wrong:

“Raising low-lying areas” can be acceptable with permits; “both” and “neither” do not reflect the nuanced reality.

Common Pitfalls:

Using grit without testing; overlooking leachate control and vector attraction reduction for organic fractions.

Final Answer:

Concreting