CESSWI CESSWI Soil Properties and Site Characterization 2 — Questions and Answers
Question 1: What is the primary purpose of conducting a pre-construction site assessment for a CESSWI inspector?
- To verify the contractor's insurance
- To identify site drainage patterns, sensitive areas, and existing erosion hazards before grading begins (Correct answer)
- To approve the grading plan for permit issuance
- To collect soil samples for laboratory analysis
Correct answer: To identify site drainage patterns, sensitive areas, and existing erosion hazards before grading begins
A pre-construction assessment establishes baseline conditions, identifies drainage flow paths, and locates environmentally sensitive areas so appropriate BMPs can be planned.
Question 2: Which soil characteristic most directly determines whether a soil is classified as cohesive or non-cohesive?
- Grain size distribution
- Clay mineral content and plasticity (Correct answer)
- Organic matter percentage
- Bulk density
Correct answer: Clay mineral content and plasticity
Cohesion in soils results from clay minerals and their plasticity; higher clay mineral content and plasticity index indicate greater inter-particle cohesion.
Question 3: On a topographic map used for site characterization, closely spaced contour lines indicate:
- Flat terrain with low erosion risk
- Steep slopes with higher erosion potential (Correct answer)
- Areas of deep soil deposition
- Wetland boundaries
Correct answer: Steep slopes with higher erosion potential
Closely spaced contour lines represent rapid elevation change over a short horizontal distance, meaning steep slopes that generate faster runoff and higher erosive energy.
Question 4: The 'LS' factor in the USLE represents:
- Land slope only
- Slope length and slope steepness combined (Correct answer)
- Soil loss per acre
- Landscape sensitivity index
Correct answer: Slope length and slope steepness combined
The LS factor accounts for both the length of the slope (L) and its steepness (S); longer and steeper slopes accumulate more runoff energy and cause greater erosion.
Question 5: When characterizing a disturbed construction site, which indicator most strongly suggests the presence of hydric soils and a potential wetland?
- Reddish-brown oxidized mottles throughout the soil profile
- Gray or bluish-green soil colors (gleying) with redoximorphic features (Correct answer)
- Sandy texture with rapid drainage
- High bulk density and low organic matter
Correct answer: Gray or bluish-green soil colors (gleying) with redoximorphic features
Gleyed colors and redoximorphic features (mottles, concretions) result from periodic saturation and anaerobic conditions characteristic of hydric soils in wetlands.
Question 6: Soil compaction from heavy construction equipment primarily affects stormwater management by:
- Increasing soil infiltration rates
- Reducing infiltration capacity and increasing runoff volume (Correct answer)
- Improving soil particle cohesion and reducing erosion
- Decreasing the plasticity index
Correct answer: Reducing infiltration capacity and increasing runoff volume
Compaction collapses soil pores, drastically reducing infiltration capacity so precipitation that would have infiltrated instead becomes surface runoff, increasing erosion risk.
CESSWI CESSWI Soil Properties and Site Characterization 2
What is the primary purpose of conducting a pre-construction site assessment for a CESSWI inspector?