2002-07-31_PERMIT FILE - M2002004

Home Browse Search

Blasting Impacts Assessment for the Proposed GCC Rio Grande, Inc. Quarry in Pueblo County, Colorado 10.00 1.00 a 0.10 a 0.01 Historical NYC Vibration Data Plot 95% Curve: PPV= 46.6(D/W - ■ ■ ti I ■ 11111161 • 0.00 1.00 10.00 100.00 Scaled Distance 1000.00 • Carnegie • Con -Ed Hunter Figure 3.4 — Historical NYC Scaled Distance —PPV Data from Blasting at Carnegie Hall, the Con - Edison Shaft at 36` Street and 1' Avenue and foundation blasting at Hunter College at between 38 and 39 Streets (NOTE: the 95% curve means that 95 percent of the time, predicted values will be lower than the value calculated). When site - specific historical data is not available, the K factor value can be estimated based on physical rock properties and degree of blast confinement. From the author's past experience, for blasts in the Fort Hayes Limestone at the Red Rock site, a prediction equation with a K factor of 240 can be used to predict vibration intensities (PPV) at various locations of concern. The resulting prediction equation, which is used in the site - specific evaluations in Section 4 of this report, is shown Equation 3.3 below. PPV = 240 0/10 Equation 3.3 Colorado regulations, enforced by the Division of Labor, restrict vibration intensities to a range of 0.75 to 2.0 in/s depending on distance. As shown later in the vibration prediction calculations for the Red Rock site, vibration intensities will be far below levels that could cause any form of damage. In addition to concerns about vibration damage, under certain conditions, humans and animals can be startled or annoyed by blast - induced ground vibration. Research has also shown that the human response to transient vibration - -like those caused by blasting - -varies depending on exposure time and the intensity of the motion. Response curves defining how humans respond to transient vibrations based on these variables are shown in Figure 3.5. REVEY Associates, Inc. Page 10 July 2002