LARE Soils and Site Conditions Flashcards

Which federal environmental law requires site assessment for contamination when land use is changing from industrial to public recreational use?

Answer: Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)

CERCLA (Superfund) establishes liability and remediation requirements for contaminated sites, and Phase I/II Environmental Site Assessments are conducted under ASTM standards to identify CERCLA liability.

What does 'angle of repose' mean in cut-and-fill grading design?

Answer: The maximum safe steepness of a slope for a given soil type before it fails

The angle of repose is the steepest angle at which a granular or cohesive soil will remain stable without sliding, and varies by soil type, moisture content, and cohesion.

On a LARE grading question, what does a 'cut' condition refer to?

Answer: Areas where existing soil is removed to lower the grade to a design elevation

A 'cut' in grading design refers to the removal of existing earth to achieve a lower finished grade, as opposed to 'fill' where earth is added to raise the grade.

What is the significance of a 'seasonal high water table' (SHWT) in site and planting design?

Answer: It affects plant selection, drainage design, and is often the control elevation for bioretention systems

The SHWT is the highest elevation that groundwater reaches seasonally, and it dictates minimum depths for underground infrastructure, influences plant selection for wet tolerance, and controls bioretention design bottom elevations.

Which soil amendment is most commonly specified to lower the pH of alkaline soils for acid-loving plants like azaleas and blueberries?

Answer: Elemental sulfur

Elemental sulfur is oxidized by soil bacteria to form sulfuric acid, which lowers soil pH, making it the standard amendment for acidifying alkaline soils.

What is 'soil compaction' in landscape construction, and what is its primary negative effect on plants?

Answer: The reduction of soil pore space due to pressure, which limits water infiltration and root penetration

Compaction reduces the macro-pore spaces between soil particles, limiting water infiltration, gas exchange, and root elongation, ultimately stunting plant growth and causing premature decline.