|Alewife Neighbors, Inc. > projects > wrgrace > 22-APR-99 Draft Airborne Asbestos Management and Monitoring Plan|
Draft version of the Airborne Asbestos Management and Monitoring Plan developed by Haley & Aldrich to control the escape of asbestos during construction activities at the Grace Site. This is the draft version from which public comments were taken through July, 1999.
AIRBORNE ASBESTOS MANAGEMENT AND MONITORING PLAN
W.R. Grace & Co.-Conn.
A conceptual airborne asbestos management and monitoring plan has been developed for the W.R. Grace & Co.-Conn. (Grace) site. It will be utilized to control potential exposures to airborne asbestos in the event of future disturbance to soil at the site resulting from large scale, intrusive maintenance or proposed development activities. Management and monitoring airborne particulates allows real-time data to be obtained that can be used to infer exposure to asbestos, since asbestos exposure data can not be obtained in real-time. The purposes of the plan include:
Throughout the excavation activities, generation of airborne asbestos will be managed at the work location, and airborne particulate monitoring will be conducted at the perimeter of the excavation and/or at the perimeter of the site to evaluate the effectiveness of the airborne asbestos management plan. If monitoring indicates the airborne asbestos management techniques being used are ineffective to control airborne particulate generation, more aggressive techniques will be employed, as outlined in this plan. If monitoring indicates less exposure potential, the controls will be relaxed.
Prior to the beginning of excavation activities, further soil characterization for the asbestos content will be completed in areas where visually detectable amounts of asbestos (Trace or percent levels) have been detected by Grace, the COC and ASG through prior investigations. The purpose of the additional characterization is to define the size of the portion of the site that will be subject to dust management protocols. Soil sampling will be conducted in a manner similar to prior programs. Samples will be analyzed using the EPA Protocol for Screening Soil and Sediment Samples for Asbestos Content (EPA Protocol), plus EPA Method 600/R-93-116, Polarized Light Microscopy (PLM).
AIRBORNE ASBESTOS MANAGEMENT
Management of airborne asbestos generation will be implemented whenever excavation activities involve an area greater than 100 square feet. One of three levels of airborne asbestos management practices will be employed at the start of the excavation, based on known concentrations of asbestos in the soil in the material to be disturbed derived from past evaluations and/or additional characterization. Data collected in this and previous investigations conducted by Grace and interested parties will be used to designate areas where Level 1 management techniques will be used at the start of excavation activities (detections of NVA). Trace and percent levels of asbestos detected by interested parties in previous programs will be used to indicate areas that will undergo further characterization for asbestos in soil, however those percent levels will not be used to determine airborne asbestos management level during excavation activities in those areas.
Management techniques, such as paving or treatment with bitumen and sand on frequently used access roads, maintaining vegetation cover, spraying exposed soil with water combined with additives, and slurry cover sprays will be considered for use at the site in addition to the techniques discussed in the following sections if deemed appropriate considering site activities. For example, to prevent airborne asbestos generation on frequently-used dirt access roads leading to the excavation, the road could either be paved, covered with clean, off-site soil, bituminous material, or a non-toxic, non-reactive and non-volatile particulate suppression wetting agent or soil stabilizer could be applied to the access road to prevent particulate generation and erosion.
To minimize the potential for tracking mud off-site, site workers will park personal vehicles in a designated parking area constructed of gravel, asphalt or other suitable material. For vehicles in contact with asbestos-containing soil, temporary wheel-wash stations will be used to prevent mud and dirt on vehicles from leaving the site.
During load-in, load-out or maintenance activities of stockpiled soil, either water or a wetting agent will be used to maintain the moisture content of the stockpiled soil. If a stockpile of asbestos-containing soil will be undisturbed for a length of time, the inactive stockpile will be sprayed with a soil stabilizer and covered with anchored plastic tarps. Soil stored on-site or leaving the site in roll-offs or haul trucks will be securely covered.
AIRBORNE ASBESTOS MANAGEMENT LEVELS
The airborne asbestos management plan is broken down into three levels of aggressiveness, beginning with Level 1, which will be used in areas where currently available data indicates No Visible Asbestos is present in the soil. Level 2 will be employed when excavations are planned in areas where data obtained by Grace indicates asbestos is present in the soil in concentrations ranging from trace levels to less than or equal to 3 percent. Level 3 will be used when excavations are planned in areas where Grace data indicates asbestos is present in the soil in concentrations equal to or greater than 4 percent.
Management Level 1
Level 1 management techniques will be used at excavations completed in areas where previously collected data indicates No Visible Asbestos is present in the soil. Level 1 will include the following management technique:
Water sprays will be used to suppress the creation of airborne asbestos at the excavation. Water will be provided from municipal mains or stored in either tanks, tank trucks, or other devices capable of providing a regulated flow and a positive shut-off. Water will be sprayed on soil exposed in and around the excavation and on soil during loading and unloading, throughout excavation activities at timed intervals, or as needed based on soil moisture conditions.
Management Level 2
Level 2 management techniques will be used for excavations completed in areas where data indicates asbestos has been detected at concentrations ranging from Trace to 3 percent are present in the soil. Level 2 will include the following management techniques:
Wind screens will be used to decrease wind velocity and soil moisture loss at exposed surfaces caused by excavation activities. Construction fencing will be erected around the excavation and wind screening, constructed of durable fabric mesh, will be attached to the construction fencing.
See above discussion.
Management Level 3
Level 3 management techniques will be used for excavations completed in areas where data indicates asbestos has been detected at concentrations equal to or above 4 percent are present in the soil. Level 3 will include the following management techniques:
See above discussion.
See above discussion.
Water Sprays with Additives
Additives include polymers, adhesives and surfactants, that when combined with water and sprayed on soil extend the waters' airborne particulate suppression effectiveness. Surfactants reduce water tension allowing for more effective coating of particles, and are the most effective agent to add to water while excavating because they do not create crusts on the soil surface like polymers, or bind and weigh the soil down like adhesives. Water-additive mixtures would be sprayed on soil exposed in and around the excavation and on soil during loading and unloading, throughout excavation activities at timed intervals, or as needed based on soil moisture conditions.
Airborne asbestos management requirements will be reduced or suspended once sufficient cover materials are in place to control potential exposure to asbestos containing soil. These materials would include clean off-site soil cover, foundation units and floor slabs.
AIRBORNE PARTICULATE MONITORING
Air monitoring will be conducted at the Grace site to evaluate airborne particulate concentrations in air during soil disturbance activities. Particulate concentrations will be monitored at the location of construction activities and at the site perimeter, depending on the size of the excavation. Monitoring will be implemented in addition to airborne asbestos management to confirm the effectiveness of the management techniques and provide criteria for increasing or decreasing management efforts as required or allowed by data.
At the Excavation or Work Site:
A construction monitoring technician will wear a particulate aerosol monitor during construction activities while monitoring at or in the excavation or work site. The data collected from the particulate aerosol monitor will quantify the levels of airborne particulate being generated in the work area such that recommendations can be made regarding the level of management to implement. The site representative will also wear personal air sampling equipment capable of collecting air samples for analytical testing for asbestos.
At the Perimeter of the Excavation and/or Site:
Air monitoring stations will be established around the perimeter of the excavation, and depending on the size of the excavation, at locations along the perimeter of the site. Up to two meteorological stations will be established based on excavation or work site size and/or location to evaluate prevailing wind directions. Meteorological information will be used to establish the positioning of the site representative with monitoring and sampling equipment and the placement of air monitoring stations.
Monitoring stations will consist of a particulate aerosol monitor and a separate sampling pump fitted with filter cassettes and filter media to collect air samples for asbestos analytical testing. The equipped monitoring stations will be inspected and manually read a minimum of four times daily to record and assess total particulate levels. On a daily basis up to three stations will be equipped with particulate monitoring devices that continuously record particulate levels based on prevailing wind direction.
Monitoring Methods and Analytical Testing
Total Airborne Particulates: Real-time particulate aerosol monitoring for total airborne particulates in the work area and at a selected number of down-wind and up- wind monitoring stations at the site perimeter will be conducted. Portable, real-time particulate aerosol monitors have the capability of measuring mass concentrations of airborne particulates, aerosols, and mists while providing real-time readouts. Particulate aerosol monitors do not identify the composition of the particles detected.
The data obtained from real-time monitoring for total airborne particulates will be compared the National Primary Ambient Air Quality Standard, or a value less than the standard, to indicate if a higher level of management is needed to adequately suppress airborne particulates at the excavation or work site.
ACTIONS TO BE TAKEN BASED ON MONITORING DATAIf, when working at Level 1, monitoring indicates dust at concentrations greater than 150 micrograms per cubic meter (mg/m3) present in the air for five readings sustained over a one- hour period, the level of management will be increased to Level 2. For work areas begun at Level 2, if monitoring indicates dust present at concentrations greater than 75 mg/m3) present in the air for five readings sustained over a one-hour period, the level of management will be increased to Level 3. At a minimum, management Level I will be employed during excavation activities, however, management levels will be decreased from Levels 2 and 3 if monitoring indicates no airborne particulates, low levels of airborne particulates, or low levels of airborne asbestos, are sustained for a period of time.