CC-1000_2018

Soil Gas Control Systems ANSI/AARST CC-1000 2018 in New Construction of Buildings 6 5.3.3 Water disposal (over ground or storm sewer) Closure for water discharge piping that opens to outside air or connects to a storm sewer shall be provided by means of a one-way flow valve with access provided for future maintenance or an equivalent method. 5.3.4 Exterior foundation wall Portions of exterior foundation wall surfaces that directly adjoin native or fill soil and are more than 3 feet (1 m) vertically higher in elevation than adjoining interior soil gas collection plenums are not required to be included in calculations for the size of joined plenums or constructed as soil gas collection plenums . These exterior foundation wall surfaces shall however be waterproofed in accordance with Sections 5.2.2 , 5.2.3 and 5.3.1 . See figure 5.3 . 5.3.5 Foundations below the water table Where it is known that foundation walls and floors will frequently be below the water table for extended durations, an evaluation shall be made for the expected vertical elevation of the water table both during floods and during droughts. When the water table is expected to be above the basement floor throughout the year, plenums below the foundation are not required. If the water table is expected to recede below the foundation for extended durations, soil gas collection plenums with soil gas vent piping shall be constructed with attention to duct routing design and soil gas inlets below the slab. Figure 5.3 Example of foundation drain systems that form a soil gas collection plenum rotated sideways. 5.4 Footings and joined plenums A means shall be designed and constructed to prevent obstruction from poured concrete and collected water for openings or ducts that traverse structural supports (e.g., footings, grade beams and thickened slab areas). Informative notes — Commonly, a pipe sleeve is placed and secured prior to casting structural supports. When geotextile mats are used for ducting, the mat is commonly mounted to a flat surface to extend ducting across structural supports prior to casting concrete. Figure 5.4 Example of traversing structural supports 5.4.1 Footing openings When air transfer is constructed with an opening in the footing (e.g., under partition doorways) rather than ducted with pipe, the size of the openings shall be no less than required in Section 5.7.1 for open inlets. When the opening is filled with gravel, it shall be sized to accommodate the combined area for unobstructed openings between stones as required in Section 5.7.1 . 5.5 Gas permeable layers 5.5.1 General A gas permeable layer shall be provided under the top of each plenum (e.g., concrete slab or vapor barrier) often described as the location for base course aggregate. Figure 5.5.1 Construction example 5.5.2 Gas permeable layer configurations Each gas permeable layer shall consist of aggregate or void space that allows hydraulic conductivity for air movement across the gas permeable layer . To ensure sufficient hydraulic conductivity, the gas permeable layer configuration shall be one of the following: a) A uniform layer not less than 4 inches (10 cm) in depth of gravel or crushed stone that meets ASTM C33 requirements for size numbers 5, 56, 57 or 6.