May 2008

University of California, San Francisco-Mission Bay Releases Noise Data for Proposed Helipad

By Kerry Fleisher

As part of its draft Environmental Impact Report (EIR) for its Mission Bay medical center, last month the University of California, San Francisco (UCSF) released a noise analysis of its hotly contested helipad, which is proposed to be located at 16th and Third streets.  The report found that the facility would meet state and federal land use requirements based on noise models derived from last year’s helicopter test flights.  Dogpatch and Mission Bay residents, however, questioned the report’s findings.  

The Helicopter Noise Report, issued by Harris Miller Miller & Hanson Inc. (HMMH), concluded that the proposed helicopter flights would not add to the 24-hour noise exposure in nearby residential areas.  Additionally, it found that no residential property outside the UCSF Mission Bay campus would be exposed to a community noise equivalent (CNEL) of greater than 65 decibels, which is the state and federal standard for compatible land use.  The results were based on a noise model that takes a sound reading of a singular event, measured in loudness and duration, and extrapolates it to a 24-hour period.

The Helicopter Noise Report determined noise exposure levels for nearby areas based on a variety of factors, including the time of day, helicopter type, and potential windshield.  The report drew its baseline measurements last year, when six sound monitors were set-up across Potrero Hill, Mission Bay, and South-of-Market for a weeklong period.  These sound monitors, plus two extras placed near the proposed helipad site, recorded sound signatures during four simulated helicopter take-off and landings, the mix of which were intended to account for prevailing wind patterns.

UCSF has estimated that there will be 1.4 helicopter transports a day—2.8 including both take-off and landing—for children with life-threatening illnesses.  Roughly two-thirds of the flights are expected to occur between 7 a.m. and 7 p.m.; one-sixth between 7 a.m. and 10 p.m.; and approximately one-quarter between 10 p.m. and 7 a.m..

HMMH determined that somewhat less than 10 percent of the area’s population may experience sleep disturbance as a result of helicopter nighttime flights, though the majority of residential areas will experience less than five percent sleep disturbance.  There are no federal or state guidelines for mitigating sleep disturbance impacts, nor is there a universally accepted method for determining such measurements.  HMMH also concluded that helicopter-induced speech interference would be limited to less than five minutes on a busy day, and less than one minute per event.  The most impacted neighborhood would depend on the helicopter type used and the windshield, according to the study.

At a community meeting held last month residents voiced a mixed bag of concerns.  Helipad opponents questioned the accuracy of the Integration Noise Model, which is required by the government based on CNEL readings.  One meeting attendee felt that the measurement method was “weird;” others called it conservative and obtuse.  Another resident asked whether UCSF had considered the impact of the sound signature on hospital patients—which would fall within the 65 decibel CNEL contour—while another wondered to what extent atmospheric conditions and wind anomalies were factored into the data.

Data for the single event noise exposure, which measures loudness and duration for one event, is also presented in the report.  The data measures both A- and C-frequencies for all nearby neighborhoods.  And the draft EIR provides a “no helipad alternative” as part of its analysis.  The report’s conclusions, however, focused solely on CNEL measurements.

HMMH recommended a “Fly Quiet Program,” in which pilots would be consulted to develop the quietest flight paths.  They also recommended that UCSF keep a detailed flight log for public review, and suggested that the University work with aviation companies to phase-out use of noisier, older helicopters.  

UCSF had already identified the concessions it’s willing to make before the draft EIR was released.  The hospital has dismissed alternative landing sites—such as placing the pad at 16th Street, on Port lands; or on the hospital’s north side—because these locations would require a secondary transfer, prompting more risks to patients.  At the proposed site, a patient will land on-site, be removed to a gurney, and transported inside the hospital within seven minutes or less.

UCSF has committed to keeping a record of transport providers, helicopter type, arrival and departure times, and departure flight paths.  The Helicopter Noise Report can be found in its entirety at  Barbara Bagot-Lopez, UCSF’s Associate Director of Community Relations, plans to hold a press conference to address hot-button helipad issues at a yet-to-be-determined date.  


Subscribe to The Potrero View

All rights reserved. Copyright © 2015 The Potrero View.

Content on this site may not be archived, retransmitted, saved in a database, or used for any commercial purpose without the express written permission of The Potrero View or its Publishers.