Toxic Air Contaminants (TAC)

Airborne dusts represent a health concern for all San Francisco residents. Respirable dust and particulate matter less than 10 microns in size are recognized as a negative impact public health. Additionally, it is known that several areas of San Francisco contain naturally occurring asbestos. Construction activities that disturb native soils may be subject to several regulations, depending on the characterization of the soil being manipulated. Airborne dusts related to construction activities are regulated by the Bay Area Air Quality Management District (BAAQMD) and San Francisco Dept of Public Health (SFDPH).

At the Mission Bay Campus, soils are also known to contain pollutants that were deposited as much as 100 years ago. The Regional Water Quality Control Board (RWQCB) augments the regulatory oversight of BAAQMD and SFDPH at Mission Bay and all three agencies have specific regulations relating to airborne dusts.

Applicable regulations include:

• The Asbestos Airborne Toxic Control Measure (ATCM) for Construction, Grading, Quarrying and Surface Mining Operations (California Code of Regulations, Title 17, Section 93015)
• San Francisco Health Code, Article 22B: Construction Dust Control Requirements

In all cases, dust control measures must be adopted for large construction projects. Depending on the presence, level and type of contamination, notification to one or more regulatory agencies may be required.

Any disturbance of naturally occurring asbestos during construction, requires the following dust mitigation measures must include:

• Construction vehicle speed at the work site must be limited to fifteen (15) miles per hour or less
• Prior to any ground disturbance, sufficient water must be applied to the area to be disturbed to prevent visible emissions from crossing the property line
• Areas to be graded or excavated must be kept adequately wetted to prevent visible emissions from crossing the property line
• Storage piles must be kept adequately wetted, treated with a chemical dust suppressant, or covered when material is not being added to or removed from the pile
• Equipment must be washed down before moving from the property onto a paved public road
• Visible track-out on the paved public road must be cleaned using wet sweeping or a HEPA filter equipped vacuum device within twenty-four (24) hours.
• All construction / grading projects that are greater than 1 acre in size are required to submit an Airborne Dust Mitigation plan to the BAAQMD prior to the start of work.

At the Mission Bay campus, all construction projects that disturb the native soils are subject to the Risk Management Plan

In the event that your project requires any “dust generating activity”, The Risk Management Plan calls for:

• a written dust plan
• daily written logs
• perimeter air sampling
• quarterly reports to the RWQCB.

Acceptable dust control measures may include one or more of the following:

• Water all active construction areas at least twice a day or as necessary to prevent visible dust plumes from migrating outside of the parcel under development.
• Enclose, cover, water twice daily, or apply (non-toxic) soil binders to exposed construction stockpiles.
• Mist or spray water while loading transportation vehicles.
• Minimize drop heights while loading transportation vehicles.
• Use tarpaulins or other effective covers for trucks carrying soils that travel on streets.
• Pave, apply water three times per day, or apply (non-toxic) soil stabilizers on all unpaved access roads, parking areas and staging areas at construction sites.
• Sweep daily all paved access routes, parking areas and staging areas.
• Sweep street daily if visible soil material is carried onto public streets.
• Install wheel washers for all exiting trucks, or wash off the tires or tracks of all trucks and equipment leaving the site.
• Installing wind breakers, or plant trees / vegetative wind breakers at windward sides of construction areas.
• Suspend excavation and grading activities when winds (instantaneous gusts) exceed 25 mph.
• Limiting the area subject to excavation, grading and other construction activities at one time.

If you are planning a large grading, trenching, landscaping, or any other soil disturbing activity, please notify UCSF Environmental Programs prior to the start of work.

The following links are provided for your information:

BAAQMD Asbestos Program: http://www.baaqmd.gov/Divisions/Compliance-and-Enforcement/Asbestos-Programs/Asbestos-ATCM.aspx