a. Portable noise enclosures (so-called "noise tents") made of steel frames wrapped with noise curtain material, such as SoundSeal model BBC-13-2, or equivalently rated material, may be built to surround the jackhammer (on the top and 3 sides) and the operator. A properly constructed enclosure, using curtain material with a Sound Transmission Class rating of STC 30 or greater, generally provides a 5 dBA insertion loss. Such barrier shall meet OSHA standards for worker exposure to particulate matter.

iii. Portable noise shields made of steel frames wrapped with noise curtain material, such as SoundSeal model BBC-13-2, or equivalently rated material, shall be used to form a noise barrier in the direction of sensitive receptors and completely block the line of sight between the receptors and vac-truck. Noise curtains are typically made out of a 1/4-inch thick heavy vinyl material, often with a noise absorptive quilt attached to one side. These noise curtains generally weigh 1.5 lbs/sq.ft., have an STC rating of about 32, and come in 4-foot wide sheets complete with grommets and Velcro edges to aid in hanging the curtains and sealing the sheets side-by-side.

iii. A noise shroud enclosure shall be wrapped around the head (i.e. chisel) of the hoe ram whenever working within 200 feet of a receptor. Shrouds may be selected from various manufacturers such as Krupp Industries, Allied Hi-Ram, Montabert, or Rammer Inc. with steel shrouds to attach to the hoe ram head. Alternatively, a shroud may be fabricated on-site by wrapping the chisel head with a heavy vinyl noise curtain material, such as SoundSeal BBC-13-2, or equivalently rated material, and securing it with a tie wire.

iii. Noise curtain material, such as SoundSeal model BBC-13-2, or equivalently rated material, shall be used to form a noise barrier in the direction of sensitive receptors and completely block the line of sight between the receptors and dump truck. It shall also be draped over the dump truck to augment the engine housing and exhaust stack. Noise curtains are typically made out of a 1/4-inch thick heavy vinyl material, often with a noise absorptive quilt attached to one side. These noise curtains generally weigh 1.5 lbs/sq.ft., have an STC rating of about 32, and come in 4-foot wide sheets complete with grommets and Velcro edges to aid in hanging the curtains and sealing the sheets side-by-side.

iii. Noise curtain material, such as SoundSeal model BBC-13-2, or equivalently rated material, shall be used to form a noise barrier in the direction of sensitive receptors and completely block the line of sight between the receptors and auger drill rig. Noise curtains are typically made out of a 1/4-inch thick heavy vinyl material, often with a noise absorptive quilt attached to one side. These noise curtains generally weigh 1.5 lbs/sq.ft., have an STC rating of about 32, and come in 4-foot wide sheets complete with grommets and Velcro edges to aid in hanging the curtains and sealing the sheets side-by-side.

iii. Portable noise enclosures made of steel frames wrapped with noise curtain material, such as SoundSeal model BBC-13-2, or equivalently rated material, shall be built to surround (top and 3 sides) the concrete saw and the operator. A well made enclosure, using curtain material with a Sound Transmission Class rating of STC 30 or greater, can generally provide a 5 dBA insertion loss providing there are no gaps in the enclosure. Noise tents may be reused at other sites with proper care and maintenance.