1982-02-18_GENERAL DOCUMENTS - M1981302

• Permit No: M1981302
• IBM Index Class Name: General Documents
• Doc Date: 2/18/1982
• Doc Name: FLATIRON SAND AND GRAVEL CO DEEPE FARM PIT SECTIONS 9 & 16 T1S R10W
• From: PLANNING DIV BOULDER CNTY
• To: MLRB
• Media Type: D
• Archive: No

i
planning divifi®n
p.o. box 471 12th o.xi ,pru(e Areet boulder, colorodo 80306 441-3930
•
MEMORANDUM
TO: Boulder County Planning Commission cdword otepe
Wd sic depertmcnt drecta
FROM: Boulder County Planning Staff :
DATE: December 11, 1981
Report on Additional Ambient Noise Level Monitoring and Proposed Noise Level
Standard for Docket #SU-81-10, Deepe Farm Pit
Since the November 18th Planning Commission hearing, the applicants' acoustic
consultant, Charles M. Salter Associates, has done additional ambient noise
level monitoring in the residential area and has submitted a report on the
results of the additional monitoring which also includes a recommended noise
level standard and monitoring program for the mining operation. The report,
which is dated December 2, 1981, is attached to this memorandum.
Staff agrees with Salter Associates on three (3) points:
1) The additional monitoring data, like the original data contained
in their October 30, 1981 report, indicates that 45 dBA is a
typical overall average ambient noise level figure for the
area. This might be expressed as an L (noise level exceeded
only 50% of the time) or an Leq (equivPent based on total
sound energy received averaged over time) of 45 dBA.
2) Staff has verified that the January 1979 aerial noise monitoring
study of Boulder done for the. EPA shows that weekend ambient
noise levels usually meet or exceed weekday ambient levels.
Since maintenance activities are the only activities to be
permitted on Saturdays and the maintenance activities are limited
to the Stage 1 operations area, which is approximately 3000 feet
from any residence, Saturday maintenance activities, although
they should still be subject to a noise level standard, should
not present a problem. Staff's conclusion is that a separate
weekend ambient level and standard is not necessary.
3) Salter Associates propose only one (1) monitoring site, which is
site #2 in their latest report and is located overlooking the
gravel pit site behind 1230 Chambers Drive. Since measurements
show that this site has the lowest ambient levels of the sites
monitored and is least affected by highway noise, staff feels
that this would be an appropriate monitoring site. It is also
a good location to monitor noise from the first two (2) stages
of mining which are being recommended for approval . Additional
monitoring sites may be necessary in the future if additional
stages of mining are approved.