CC-1000_2018

CC-1000 Companion Guidance (1-2018) CC-1000 Companion Guidance CG Page of 12 Informational 4 5.4 Footings and joined plenums Advisory — Designs must not result in obstructed air ducting due to poor planning or events during grading or concrete pour. EXAMPLES WHEN DUCTWORK MUST TRAVERSE STRUCTURAL SUPPORTS 5.5 Gas permeable layers Design & Installation Detail 5.5.1 General Absence of a gas permeable layer leaves the migration path of soil gas unpredictable as well as uncontrollable. 5.5.2 Gas permeable layer configurations For minimizing energy required to counter the driving force of stack effect, agas permeable layer with abundant hydraulic conductivity is needed. Comparisons for Hydraulic Conductivity of Natural Soils and Aggregates GREY HIGHLIGHTS INDICATE MATERIALS NOT CONSIDERED GAS PERMEABLE Range of Hydraulic Conductivity of Natural Soils USCS Soil Type Hydraulic Conductivity Range Permeability description class gallons per day/ft 2 GP Uniform gravel 4,000 to 20,000 High GW Well-graded gravel 1,000 to 6,000 Moderate to high SP Uniform sand 100 to 4,000 Moderate to high SW Well-graded sand 20 to 2,000 Low to moderate SM Silty sand 20 to 100 Low SC Clayey sand 20 to 20 Low to very low ML Silt 1 to 2 Very low CL Clay 0.02 to 0.2 Very low to impermeable Examples of Soil Characterization (AASHTO - American Association of State Highway and Transportation Officials) Aggregate Classification Aggregate Classification A-1 to A-3 A-4 to A-7 Granular Materials ( ≤ 35% passes #200 Sieve) Silt-Clay Materials ( ≥ 36% passes #200 Sieve) A-1 materials are well graded, whereas A-3 soils are clean, poorly graded sands A-4 & A-5 are generally silts A-6 & A-7 are generally clays