Bay Area Rapid Tranist District Answers Community ConcernsBy Lynne Hosley
May 23, 2000
TO: Jim Tousey
BART Stations Management
FROM: Lynne Hosley
Environmental Compliance Manager
SUBJECT: Bay Area Rapid Transit District
West Bay Extension
Contract No. 12YC-120
Between 1997 and 1999, BART performed extensive soil and groundwater sampling and testing along the entire Right Of Way. The sampling resulted in the identification of several areas within the City of San Bruno where levels of chemicals such as arsenic, lead, and motor oil exceeded project action levels. None of these areas exhibit levels of contamination sufficient to be considered hazardous materials under state or federal law. However, since these levels exceeded background levels naturally occurring within the San Francisco Bay Area, BART is taking steps to ensure the safety of human health and the environment. BART's Soil Management Plan presents the methods for handling all soils excavated during construction and has been approved by the Regional Water Quality Control Board (RWQCB). Specific areas where elevated levels are found include the future San Bruno Station and several areas adjacent to Huntington Avenue reaching from the San Bruno Station to Sylvan Avenue.
Along the Bart alignment, impacted soils are typically limited to the top few feet of the excavation. These areas are excavated by specially trained crews under direct supervision of Tudor-Saliba/Slattery's Site Safety and Health Officer (SSHO) as well as BART's environmental consultants. During the excavation of contaminated soil, the contractor adheres to a site-specific work plan that requires site monitoring, dust mitigation, and other safety controls in place to ensure worker safety. Controls include wetting of excavated soil to minimize dust, covering of trucks during transportation of soil, barriers between the impacted areas and the public, decontamination of excavation equipment, and routine monitoring of dust levels in the work area. Additional protective measures for employees directly in contact with the impacted soils include training, daily preconstruction meetings, and personal protective equipment.
Monitoring is performed to ensure that workers are not exposed to levels of arsenic above the Permissible Exposure Limit (PEL). The PEL is a level at which a worker can be exposed for 8 hours per day for a 30 year career without suffering adverse health effects. To date, PELs have not been exceeded during work within areas of concern. The duration of work to remove these soils from each area is limited to a few hours for a few days at a time, after which the elevated levels of arsenic are no longer present. For example, the excavation of impacted soils along Huntington Avenue near Euclid Street took place between 0700 and 0930 on May 2nd, 2000. The excavation area was clearly delineated with caution tape, and only properly trained personnel were allowed to enter. A "tailgate" meeting was held before the start of work to remind employees of health and safety requirements. Employees in close proximity to the excavation donned personal protective equipment, including Tyvek coveralls, gloves, hardhats, safety glasses, work boots, and hearing protection. Airborne dust levels were continuously monitored by the SSHO, and workers minimized dust levels by spraying water from the on-site water truck. Air quality monitoring of the excavation activities showed that levles did not exceed safety limits described above. After each truck was loaded with soil, workers covered the bed with a tarp and brushed the tires clean of loose soil. Loose soils were collected with a shovel and off-hauled.
In response to the concern regarding the possibility of arsenic-contaminated run-off from stockpiles along old Huntington Avenue, soils stockpiled there did not have elevated levels of arsenic. The soils were excavated near the north end of the San Bruno Station and had previously been identified as having levels of arsenic at or below those naturally occurring in Bay Area soil.
In general, when soils are excavated they are either disposed of, reused, or stockpiled on site pending further analysis. The stockpiles located under I-380 along old Huntington Avenue were covered with heavy plastic sheeting and sedimentation controls were implemented per the Storm Water Pollution Prevention Plan (SWPPP). After an extensive soil stockpile sampling program, the soils were found to contain trace amounts of petroleum hydrocarbons. Previous in-situ analysis of these same soils indicate arsenic levels at or below background.
Remaining areas where controls are required during excavation within the City of San Bruno include:
- Just north of I-380 along Huntington Avenue
- Along the 'Shoofly', near Florida Avenue
The same standard of care will be applied to all operations during the removal and transportation of these remaining soils.
Cc: Gary Jensen
Copyright ©2000 Lynne Hosley. Published 05/23/2000.