A system for retaining a flowable and curable building material to form a portion of a foundation of at least a portion of a structure of interest, the system comprising: side walls (262, 264) receiving and retaining the building material in a channel bound by the side walls, the side walls disposed in a predetermined configuration suitable for the portion of the foundation, the side walls including a first side wall and a second side wall, at least one of the first side wall and the second side wall is comprised of two or more stacked components (262A, 262B), at least one of the components having an interior cavity that traverses the component; a bracket assembly retaining the side walls in the predetermined configuration, the bracket assembly including: two or more reinforcement posts; a separator bar having a first end, a second end opposed from the first end, and a plurality of apertures (232, 234) disposed along a length of the separator bar, the plurality of apertures including a first set of apertures disposed proximate the first end and a second set of apertures disposed proximate the second end, the first set apertures and the second set of apertures are sized to receive and retain a pair of the reinforcement posts at locations to establish a width of the components of the first side wall, a width of the components of the second side wall and a width of the channel being formed therebetween; and characterized by two or more spacers mounted to and at a vertical location about the two or more reinforcement posts to horizontally and vertically offset the two or more stacked components (262A, 262B) of the at least one first side wall and the second side wall such that a cross section of the channel being formed approximates a trapezoid shape. side walls (262, 264) receiving and retaining the building material in a channel bound by the side walls, the side walls disposed in a predetermined configuration suitable for the portion of the foundation, the side walls including a first side wall and a second side wall, at least one of the first side wall and the second side wall is comprised of two or more stacked components (262A, 262B), at least one of the components having an interior cavity that traverses the component; a bracket assembly retaining the side walls in the predetermined configuration, the bracket assembly including: two or more reinforcement posts; a separator bar having a first end, a second end opposed from the first end, and a plurality of apertures (232, 234) disposed along a length of the separator bar, the plurality of apertures including a first set of apertures disposed proximate the first end and a second set of apertures disposed proximate the second end, the first set apertures and the second set of apertures are sized to receive and retain a pair of the reinforcement posts at locations to establish a width of the components of the first side wall, a width of the components of the second side wall and a width of the channel being formed therebetween; and characterized by two or more spacers mounted to and at a vertical location about the two or more reinforcement posts to horizontally and vertically offset the two or more stacked components (262A, 262B) of the at least one first side wall and the second side wall such that a cross section of the channel being formed approximates a trapezoid shape. two or more reinforcement posts; a separator bar having a first end, a second end opposed from the first end, and a plurality of apertures (232, 234) disposed along a length of the separator bar, the plurality of apertures including a first set of apertures disposed proximate the first end and a second set of apertures disposed proximate the second end, the first set apertures and the second set of apertures are sized to receive and retain a pair of the reinforcement posts at locations to establish a width of the components of the first side wall, a width of the components of the second side wall and a width of the channel being formed therebetween; and characterized by two or more spacers mounted to and at a vertical location about the two or more reinforcement posts to horizontally and vertically offset the two or more stacked components (262A, 262B) of the at least one first side wall and the second side wall such that a cross section of the channel being formed approximates a trapezoid shape.